Zhejiang Feida Environmental Science & Technology Co.,Ltd.

Electrostatic Precipitators Operator ’s Manual

Address: 88 Wangyun Road, Zhuji City, Zhejiang Province

TEL: +86-575-7212511

FAX: +86-575-7214695

E-mail: Feida@mail.sxptt.zj.cn

Post code: 311800

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Contents

1. Subject and Coverage

2. Quoted Standar ds

3. General

4. Principle of Operation

5. Briefing of Equipment

6. Installation, Check and Adjustment of Equipment

7. Safety Regulations of Equipment

8. Trial Run of Equipment

9. Operation Regulations of Equipment

10. Maintenance and Troubleshooting of Equipment

11. Quick-wear Parts and Spare Parts Provided with Equipment

12. Special Tools

13. Annex A: Electrostatic Precipitator—Program of Commissioning

(For Reference)

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1. Subject and Coverage

This standard defines the operating conditions, verification criteria, methods of adjustment, trial run, operation, maintenance and troubleshooting, and safety points for attention regarding electrostatic precipitators (ESPs).

This standard is suitable for the commissioning, operation and maintenance of dry plate-type horizontal F-model ESPs in industries of thermal power generation, metallurgy, paper-making, building materials, chemicals, etc. This standard can be used as reference code for GP-model and ZH-model ESPs.

For wet type and vertical ESPs, this standard is not suitable.

2. Quoted Standar ds

Q/XDC07-90 Electrostatic Precipitator—Installation Manual

JB6406-92 Electrostatic Precipitator—Safety Technical Regulations of Commissioning Operation

and Maintenance

JB5910-91 Electrostatic Precipitator—Technical Conditions

GB/T133931-92 Electrostatic Precipitator—Method of Performance Test

3. General

The ESP is a highly-efficient, energy-saving equipment for air cleaning, having merits of high collection efficiency, large gas volume to be treated, long life span and low cost of maintenance. At present, the requirements for environmental protection are becoming more and more stringent, and ESPs are used more widely, During the operation of an ESP, its operators’ manual must be strictly followed. Any points not dealt with in this standard should be handl ed as per the require-ments set in ESP drawings and documents.

3.1 Model Designation

Our ESPs have their model number s with the designation as follows Example:

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3.2 Application Conditions and Verification Criteria

ESPs can be used to treat flue gas that contains corrosives (called anticorrosive ESPs)

ESPs are not suitable for the treatment of flammable and/or explosive gases.

Range of ESP appliac ation:

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Gas volume: ≤4.5*108m3/h

Gas temperature: ≤400℃

Gas pressure: -6.0*104 to 0 Pa

Passage spacing: 250 to 600mm

Inlet dist loading: ≤100g/Nm3

Other ranges for performance verification (under designed operation conditions):

Pressures drop across ESP proper: ≤400Pa.

Air leakage: ≤5%

Collection efficiency: ≤the figure stipulated in the technical agreement.

The design of our ESPs are carried out according to the parameters provided by the customers, such as operation conditions, gas properties, geographic environment, requirement for environmental protection, etc. Therefore, the application conditions and verification criteria of our ESPs should be in conformity with those stipulated in the technical agreement.

4. Principle of Operation

The principle of dust collection in an ESP is as follows:

When passing through the high voltage electrostatic fields, dust particles will be charged by colliding with positive ions, negative ions and electrons or in the ion dispersion movement. The particles with electrons and ions on them will then move, under the influence of the electric field, toward and later accumulate on the electrodes of opposite polarity. By means of rapping, the layer of dust particles on the electrodes will be dislodged into the bottom hopper s.

Practice that shown that the hither the strength of electrostatic field, the more effective as ESP will be, and that it is preferable to have an ESP operating with negative corona. Therefore, our ESPs are designed in the structure of high voltage negative corona electrodes with flowchart as follows:

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5. Briefing of Equipment

Structurally an ESP is divided into two portions, electrical portion and mechanical portion. Figure 1 shows the configuration and structure of an ESP. An ESP’s main components and their functions are described below.

5.1 Electrical Portion

The electrical portion consists of high voltage DC power sources (including their control system) and low voltage control system.

5.1.1 Conventionally we use Model G G A J 02 high voltage power sources. Designation of the model is as

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follows:

Such a set of power source usually consists of high voltage transformer-rectifier, auto-control cabinet and

reactor, or of high impedanc e transformer-rectifier and auto-control cabinet.

This power source can automatically adjust the voltage applied to the electric field according to the changes of gas conditions therein and can adjust the spark ratio in the field to the optimum level so as to achieve the highest results of dust collection.

This power source is equipped with perfect interlocking protective system.

On customer ’s request, it is possible to add to this power source devices for remote control and remote measurement.

5.1.2 Low Voltage Control System and Its Functions:

a. Programmable control of rapping for both collecting and emitting elec trodes;

b. Control of heating for high voltage insulators and of alarm for low temperature;

c. Control of indication and warning for ash level;

d. Control of conveying collected ash;

e. Control of safety inter locking of doors, holes and cabinets;

f. Control of safe auto ear thing for trips;

g. Measurement and indic ation of temperatures at inlet and outlet;

h. Remote control and remote measurement;

i. Indication of comprehensive signals and alarms.

Note: Above functions are selected according to needs.

5.2 Mechanical Portion

This portion can be divided structurally into internals, casing and aux iliaries.

5.2.1 Internals

5.2.1.1 Collecting System

The collecting system consists of suspension devices, collecting plates, shock bars, etc.

Collecting plates are shaped with steel coils 1.2 to 1.5 in thickness on special rolling machines. At present,

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our plant can provide two kinds of collecting plates 480C type and 735 C type.

The curtain of collecting plates linked together must have good rigidity, and its flatness should be kept within the specified range so as to assure the limited deviation of distance between the collecting and emitting electrodes.

5.2.1.2 Emitting System

The emitting system consists of suspension devices, top horizontal beam, vertical beam, upper, middle and lower frames, discharge wires, etc. The discharge wires are manufactured by special equipment. Two types of discharge wires can be offered by our plant, i. e tubular barbed wire and spiral wire.

Emitting suspension devices are used to support the emitting system from the top girders and to connect with high voltage of negativ e polarity.

The function of the planar structure combined by vertical beam, top horizontal beam, angle iron, etc. is to fix the upper, middle and lower frames and the emitting rapping shafts.

The upper, middle and lower frames are the holders of discharge wires.

5.2.1.3 Rapping Systems

Collecting rapping system consists of drive, shaft, plain bearing, etc. Normally it is driven from the ESP side.

Emitting rapping system consists of drive, vertical shaft, pin wheels, rapping shaft, plain bearing, etc. (for top-driven design) or of drive, shaft, plain bear ing, etc. (for side-drive design).

Rapping devices are important for ESPs. By rapping, dust accumulated on both collecting plates and discharge wires is dislodged and falls into hoppers.

Both collecting and emitting rapping systems use tubbling hammer s to carry out side rapping.

Since the plain bearings are attached to the elements of emitting system at negative high voltage, to isolate the high yoltage, a porcelain shaft insulator is inserted between two runs of the same emitting rapping shaft.

5.2.2 Casing

5.2.2.1 Inlet Nozzle (Inlet Funnel)

The inlet nozzle is the transition between the inlet flue duct and the ESP casing. Inside the inlet nozzle there are 2 or 3 layers of gas distribution screens to make the passing flue gas enter the ESP field as uniformly as possible.

The gas flow wil speed down when passing through the nozzle and some dust of bigger particles will accumulate by natural settlement on the distribution screens and the nozzle. So some ESPs treating flue gas containing clogging dust are equipped with hot- air purging system and distribution screen rapping devices (similar to collecting rapper).

5.2.2.2 Outlet Nozzle (Outlet Funnel)

The outlet nozzle lets the cleaned flue gas go into the exhaust flue duct. The structure and shape of outlet nozzle has something to do with gas distribution. Under normal conditions, a row of outlet gas distribution screens (channeled plates with no holes ) is installed at the interface between the outlet noz zle and the casing.

5.2.2.3 Roofs

Roofs conist of inner roof and outer roof, of which the top girder is a key element as it carries heavy loads from both the collecting and emitting systems. High voltage power from the power source (no matter it lies on ESP top or on ground level ) is fed in through the top girder to the emitting system. To guarantee good insulating

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status of the support insulators, heating devices are equipped within the insulator compartments to maintain their dryness. Two types of heating can be adopted , electric heating or electric heating plus hot-air heating.

5.2.2.4 Casing

The ESP casing is made up of columns, side panels, end panels, pipe bracings, etc. Casing, together with nozzles, roofs and hoppers, forms a sealed container.

On the side panels there are access doors.

5.2.2.5 Hopper and Hopper Ridge Beam

The hopper ridge beam is used to connect the hoppers to the casing

The hopper is a container for collecting dislodged dust. To prevent flue gas from bypassing the hoppers, as will reduce the collection efficiency, anti-sneaking baffles are installed in the hoppers. To guarantee that ash can flow down by itself in the hopper, the hopper must have a right valley angle. To avoid condensation oc currence as the result of dust temperature falling to below the dew point, heating is applied to the lower part of the hopper (in some cases, all over the hopper), Two types of hopper heating are at choice; electric heating or steam heating.

From the flange at the hopper bottom, pneumatic ash conveying system of gate valve and discharge valve can be connected.

5.2.3 Auxiliaries

5.2.3.1 Stairs & platforms

These are provided for easy access to different locations at various levels so as to carry out operations and maintenance.

5.2.3.2 Suppor t Bearings

Support bearings are placed between the ESP casing and its support elements (concrete pillars or steel columns). Beside supporting the ESP loading, the bearings compensate displacement caused by thermal expansion, since the ESP is a hot body when in operation w hile its support elements are cold.

Support bearings usually take the form of plate type compound material (friction pad) slide bearings. But plane ball bear ings are sometimes sued in ESPs of medium size or smaller.

5.2.3.3 Thermal Insulation

To ensure the normal operation of an ESP and to prevent gas temperature from dropping to below the dew point, thermal insulation should be laid ov er the ESP casing.

The function of the thermal insulation is to reduce heat exchange. By applying thermal insulation, the minimum gas temperature must be guaranteed at a level as high as 20 to 30℃ above the dew point.

The structural design of ESP thermal insulation should specify the kind of insulating material, its thickness, type of lagging, respective quantities, etc.

The scope of work for thermal insulation is to be in conformity with that stipulated is the contract of supply.

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5.2.3.4 Ear thing

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The ESP is operating under high voltage and normally with negative corona, which means its casing and collecting system have the same potential. To protect high voltage equipment and ensure personal safety, the ESP must be earthed reliably with requirements as follows:

a. Resistance of the earthed grid should be less than 2 ohms all the year round;

b. The arrangement of the earthed grid should be such that the surroundings have n even voltage to ground.

6. Installation, Check and Adjustment of Equipment

6.1 The installation of the equipment s hould meet the requirements in Standard Q/ZDC07.

6.2 Check and Adjustment of Equipment

Respective check and adjustment should be made to the electric and mechanical portions after the equipment is erected but prior to its being put into oper ation.

6.2.1 Check and Adjustment of Mechanical Portion

6.2.1.1 Make second corrections of any deformed or bent collecting plates and discharge wires within the electric fields to ensure that all the distances between opposite electrodes are kept within the following deviations; for ESPs with plate height H≤7m, this deviation is ±5mm and for H>7m, ±10mm.

6.2.1.2 Make adjustments in the electric fields wherever the distance between parts at high and low potentials is less than the distance between oppos ite electrodes.

6.2.1.3 Check all the bolts and nuts to see that they are properly tightened and w elded dead.

6.2.1.4 Check to see that the contact positions between the rapping hammers and anvils are exactly as required on the approved drawings, and that the shafts and hammers can rotate freely.

6.2.1.5 Remove all foreign mater ials left within the electric fields.

6.2.1.6 Check to see that the motors for dampers, rapping ,ash discharge, etc. have the correct direction of revolution, that they can turn freely, tht the chains are mounted with proper tension and that all locations calling for lubrication have been oiled or greased. For methods of commissioning, refer to Annex A.

6.2.1.7 Check to see that all the insulators are mounted steady, under evenly distributed loads and kept dry and clean.

6.2.1.8 Check to see that different parts of the ESP casing and all inspection doors are properly sealed. Make gas-tithtness tests as per Annex A.

6.2.1.9 The rapping system is designed on the principles of improving the dust dislodging effects, reducing dust reentrainment, enhancing collection efficiency, lengthen the life span of rapping elements and minimizing the degree of complicacy of electric control for rapping. For details, refer to the ESP electric technical agreement of the project. After a period of trial run, the rapping system is to be adjusted to its optimum mode.

6.2.1.10 For details of the ON-OFF of ash discharge valve at hopper lower end, refer to the ESP electric technical agreement, and adjustments can be made according to the operation results. If pneumatic ash conveying system is used, there is no need for ash discharge valve. In such a case, the hopper outlet is connected direct to the ash transmitter, and the discharge of ash is by means of the inlet valve on the transmitter.

6.2.1.11 Actual gas distribution devices are designed and manufactured on the acceptable results of gas distribution tests with a scale model. Experience shows that the results of insitu gas distribution tests are always better than those from model tests. So it is specified that no adjustment test is to be made insitu on the gas distribution dev ices.

6.2.2 Check and Adjustment of Electric Portion

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6.2.2.1 Measure the ground resistance of the ESP proper and see that it is less than 2 ohms. Measure the ground resistance of electric equipment and see that it is less tan 1 ohm.

6.2.2.2 Use a 2500V mega meter to measure the insulation resistance of the high voltage network and make sure it is larger tan 1000 megohms .

6.2.2.3 The cable between the ESP casing and the positive tesrminal in the high voltage transformer-rectifier should be in good order and firmly secured.

6.2.2.4 Use a 500V mega meter to measure the insulation resistance of all motors and their cables and make sure it is not less than 0.5 megohms .

6.2.2.5 Check to see that the operating mechanism in the high voltage isolating switchgear has high movility and can be set to the exact positions.

6.2.2.6 Check to see that all wiring between different electric parts is correctly laid as per approved product drawings.

6.2.2.7 Adjust the spark frequeney is accordance with the electric conductivity of flow gas and the required collection efficiency. On the high voltage circuit control cubicle there is a control potentlometer showing the rates of voltage climb and voltage drop. The potentiometer be used to adjust the spark ratio by means of a pair of long-life indication lamps for sparkover and are quench. When there is a spark in the field, the electronic flash lamp will shine once, so the spark frequency aca be counted by using a stop watch. It is also possible to pre-set the spark rates within the following ranges; 60-80 sparks/minute for inlet field, 40-60 sparks/minute for middle field(s) and 20-40 sparks/minute for outlet field. Perhaps these figures are found to be improper after a period of operation, then adjust them until an optimum rate is reached.

Microprocessor-controlled thyristor transformer-rectifier has multiple functions such as automatic tracing of sparks, therefore it will make an ESP operate under optimum status, hence obtaining the realistic collection efficiency and having the lowest operating cost.

5.2.2.8 The set value of the thermostat for insulator heating is normally 15-25℃ above the gas dew point. It is required that the electric heaters are energied when the temperature falls below the lower limit and de-energized when the temperature exceeds the upper limit, and that an alarm will be activated when the temperature drops below the dew point. The controls should be adjus ted according to the above requirements.

6.2.2.9 Electric control circuits are to be adjus ted according to the specified rapping and ash dis charge systems.

6.2.2.10 For various items in electric commissioning, refer to Annex A or the instructions provided by the electric manufacturers.

7. Safety Regulations of Equipment

ESP operators and those working temporarily in an ESP must have the general knowledge of safety and as a special requirement, must abide by Standard JB6407. There should be special personnel to be in charge of safety.

7.1 Personal Safety

7.1.1 The ESP is a high voltage installation, so special attention must be paid to personal safety. Whenever the inlet part of high voltage T/R and the insulator compartment are in service, any parser must be away from them by a safe distance.

7.1.2 The inside of any electric field is a dangerous area of high voltage and no one is allowed to enter during the operation of the ESP, All inspection doors must be inter locked for safety.

7.1.3 Boards or signs bearing Danger High Voltage must be hung on each of the control cubicles in the control room, on cable trays and trenches, on inspection doors and on all high voltage equipment, They are not to be moved at random of approached by non-operators.

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7.1.4 The ESP is a high-altitude installation, so the stairs, platforms and handruils must be reliably strong, and no accummlation of water or snow is allowed thereon. Also all the walkways should be free of odds and ends or needless objects.

7.1.5 When performing inspection, maintenance, measurement at high altitude, no matter it is outside the ESP casing or at high-located parts inside the ESP, personnel must wear safety helmets and tie safety belts that have ropes connected or can automatically lock.

7.1.6 The ESP is an installation operating at high temperature, high negative pressure and dusty condition, so no part of the human body is allowed to touch any hot part of the ESP in operation. When the ESP is shut down for inspection/maintenance, the doors should be spened to cool down the inside temperature to below 40℃ before people can enter.

7.1.7 Should any door is left open during the operation of ESP, anyone near the door is likely to be sucked in due to high negative pressure, resulting is bodily injures and even electric shock. Therefore, the doors must be interlocked.

7.1.8 Personnel to enter the ESP must wear safety helmets well-sealed protective overalls, shoes and gloves.

7.1.9 TO avoid human bodies from being infected by smoke and dust, wash the body and protective overall after the construction is finished.

7.1.10 Wear a gas mask when you want to enter the ESP where there is too much dust and smoke.

7.1.11 If the air inside the ESP contains less than 20% oxygen, or if the air contains many different kinds of gases, it is a must to use compressed air for breathing.

7.2 Safety Checks of Equipment

7.2.1 Make regular checks of the earthing cabling and other connections to see if they have good electric conductivity and if other protective devices are in good order.

7.2.2 make sure that all the locks on boxes for relays and switches are reliable, so that irrelevant personnel can not open them eas ily.

7.2.3 The voltage of por table lamps for use in the ESP should not exceed 12 V AC.

7.3 Safety Measures during T/R Maintenance

7.3.1 Make sure that the transformer-rectifier (T/R) has been de-energized with its safety switch located in OFF position and locked with a lock.

7.3.2 Check to see that all the switches on the control panel are in OFF pos itions.

7.3.3 A sign showing “T/R Under Repair” should be placed in an eye-catching position in front of the control panel.

7.3.4 Check to see if the earthing terminal is well earthed.

7.3.5 Earth the T/R high voltage parts with the earthing devices provided.

7.3.6 Make sure the above s teps have been executed before T/R maintenance.

7.4 Safety Measures for Maintenance ins ide ESP

7.4.1 A sign showing “People Inside ESP” should be placed in an eye-catching position in front of the control panel.

7.4.2 For maintenance inside the ESP, at least 2 persons are needed and one of them is in charge of monitoring. Maintainers of ESP must be familiar with the design of the ESP as well as the function of its various parts and components, They should also know the properties of the gas and the dust, their potential harms and the

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effective protective measures to be taken.

7.4.3 The shutdown of an ESP and personnol to enter it should follow the regulations listed below:

a. Strictly follow the specifications set in 7.1 above.

b. Take the steps set in 7.3 above.

c. Turn off the safety switches of all rapping motors and the motor for ash discharge valve and secure them with locks.

d. Turn the switches of ESP blower and I.D. fan to OFF position and secure them with locks.

f. Shut off the dampers in ESP inlet and outlet flue ducts, turn off the damper electric actuators and secure them with locks.

g. Open all the inspection (access) doors to ventilate the ESP inside and wait for the temperature to drop to below 40℃ before people can enter. To speed the process of cooling, the dampers in outlet flue ducts can be opened and the I.D . fan turned on. But in such a case, the access doors must be locked in their open positions to avoid sudden closing.

h. Maintainers entering the ESP should be aware of the risk of being scalded because of different degrees in cooling for different parts and components.

i. After entering the ESP, maintainers should first inspect to see if there is dust accumulated somewhere. If there is, clean it to avoid mishaps. At the same time, the causes for dust accumulation should be worked out.

j. When the maintenance is finished, maintainers should check their tools lest some of them are left to impair ESP function.

8. Trial Run of Equipment

8.1 To ensure the reliability of operation of the ESP, before a new installation is put into formal service after erection and commissioning or before an old installation is to resume operation after a ling period of stoppage, a pre-operation trial run must be made.

8.1.1 An experienced engineer should be appointed to be the general director of the trial run. And the items to be checked should be planned, and strict site records be kept. To avoid damages caused by condensation of moisture in flue gas or by not inspecting all the parts and components during operation, the following checks should be made:

a. Check to confirm all the items listed in 6.2 above have been carried out with acceptable results.

b. All the doors of thermal insulated boxes are locked.

c. All the inspection doors are. Closed and inter locked.

d. Check the openableness of flue duct dampers to ensure reliable operation both manually and electrically.

e. Check the alarm functions on the electric control panels by pressing the “TEST” buttons thereon to simulate alarming status.

f. Check to see if the power net voltage is correct.

g. Check to confirm that no one is inside the ESP or within other dangerous areas of high voltage.

8.1.2 After all the pre-operation items of inspection have been made with acceptable results, perform the following operations:

a. Turn on the elec tric heaters for each insulator.

b. Switch on the motors for rapping and as h discharge and keep them running for 30 minutes.

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c. Detach the earthing devices from the high voltage parts to have an open circuit between the emitting an d collecting system.

d. Turn of the isolating switches of the power units and lock them in the operation positions.

8.1.3 Energization—Turn on the automatic voltage-adjusting system and observe the conditions of rise for no-load voltage.

8.1.4 If it is necessary to observe conditions of corona flashover inside the ESP, it should be organized by the general director personally and special attention should be paid to personal safety in front of high voltage.

8.1.5 Keep records of the changes in primary voltage and current and secondary voltage and current. Since the no-load current has something to do with the temperature and humidity of the air at the very time and location of the trial run, pay attention to the capacity of the equipment and v alues of voltage and current.

8.1.6 After the trial run is over, analyze and eliminate all the troubles occurred during the trial run.

8.1.7 Plot the voltage-current characteristic curves for each electric field. On a sheet of co-ordinate paper mark the values of voltage corresponding to a certain degree of increase in current until the current reaches its rated value. Connecting the points together will result in a curve, which is called voltage-current characteristic curve, and which can be used as reference for the check of erection quality and for comparison with later no-load curves of the same electric field.

8.1.8 Lead flue gas into the electric fields to warm them. When the inside temperature is higher than the dew point of gas (the insulator compartments should be heated first to gradually rise the temperature to the range of set values), high voltage can be applied to the electric fields. The auto-control system for both voltage and current should be observed for its operative conditions. At this time, the values of current and voltage may somewhat be less than those at no-load. And the spark frequency can be adjus ted accordingly so as to obtain an optimum spark rate during practical operation.

8.1.9 Keep records of the on-load primary voltage and cur rent and secondary voltage and current.

8.1.10 Using the same method as described in 8.2.7 abov e to plot the on-load V-A curves and analyze them.

8.1.11 Re-check the air leakage status of the ESP casing, inspection door, etc.

8.1.12 Shut the ESP down. (Refer to 9.5 below for details.)

8.1.13 Check the inside of the support insulator, the shaft insulator and both sides of the gas distribution screen to see if there is dust accumulated or if they are damaged.

8.1.14 Eliminate all the troubles occurred during the on-loal trial run.

9. Operation Regulations of Equipment

9.1 The ESP should be operated and managed by professional people, who must have a comprehensive knowledge of the equipment properties, operation requirements and safe maintenance, and who are familiar with THIS MANUAL. The owner of the ESP must first have these people qualified by means of examination and c heck before they are to operate and manage the ESP.

9.2 Before the start of ESP operation, make a final strict check of the equipment, keep inspection records for each item and the records should be signed and approved by the person in charge of field operation.

9.3 Start-up of ESP

9.3.1 Make sure that pre-operation inspection is over, all the safety measures are taken and all the operators are in place.

9.3.2 All the heaters have been turned on for at least 8 hours before the start-up of ESP, so as to ensure the inside of all hoppers and various insulators (support insulators, shaft insulators, etc) are dry and to avoid any

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damage caused by electric creep age due to condensation. Check all electric heaters to see if the current is correct.

9.3.3 Open all the dampers in inlet and outlet flue ducts (but with the exception of those in inlet and outlet interconnecting sections).

9.3.4 Start the I.D. fan

9.3.5 Lead flue gas into the ESP to eliminate the moisture on various internals. This period of warm-up depends on the temperature and humidity within each field and is usually ended when the temperature at the outlet of the last field reaches higher than gas dew point. At this time, be sure to let go the moisture from within the insulator compartments. When the temperature of gas at ESP outlet remains lower than dew point, never put the high voltage T/R into operation.

9.3.6 Start the ash discharge system.

9.3.7 Start all the rapping dev ices.

9.3.8 Turn on all the func tions of the low voltage operating system. Set alarms, inter locking, temperature detector and controller, ash level indicator, ash discharger, etc. all in a mode of auto-controlled operation.

9.3.9 To avoid ESP operation being hindered due to the mixture of oil and ash adhering to both collecting and emitting systems, the power switches of ESP high voltage control cubicles are not to be turned on until the boiler is in steady operation and the oil guns are withdrawn. After the power switches are turned on, press down the start buttons to initiate all functions of the high voltage control system. Wait for the field voltage rising to the flashover point before putting the elec tric fields into operation.

9.4 Operation process

9.4.1 There should be sufficient people on duty in the ESP control room. They should make regular checks to the operation of the equipment. They should search for abnormal phenomena, analyze the causes of troubles and solve them. For each work shift, at least two checks should be made to the transformers and all rotary devices to see if they function properly.

9.4.2 Main items to be inspected are as follows:

a. Check to see that the operating current of each heating system is correct. Low current will result in heating element damage.

b. Check all the indicator lamps and alarms to see if they function properly.

c. check to see if the values of primary current A, secondary current mA and secondary voltage KV as indicated by the rectifiers are correct.

d. Check to see if the ash discharge system has any problem in discharging the collected ash.

c. Regularly check to see if the rapping shafts turn normally and the hammers hit properly (as can be heard from outside of ESP).

9.4.3 Observe and optimize the spark ratio. Rapping sequence and ash discharge program of each electric field until a satisfactory collection efficiency is obtained.

9.4.4 Persons on duty must keep records of the operation status of the equipment, especially the primary current and voltage and the s econdary current and voltage, which are to be recorded on a 2-hour base.

9.5 Shut-down of ESP

9.5.1 Temporary shut-down

a. Switch off the I.D. fans and isolate the gas flow in flue ducts. Wait for 3 to 5 minutes;

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b. Switch off, in the order of electric fields, the high voltage power source to each bus section and have the control cubicles locked;

c. Shut off all the dampers in both inlet and outlet flbue ducts;

d. Keep in operation the rapping and heating s ystems;

e. If people are to enter the ESP for maintenance, earth the high voltage parts, stop the rapping systems and wait for the ESP to cool down.

9.5.2 Long-term shut-down

a. Complete Steps a, b and c in 9.5.1 above;

b. Turn off the isolating switch to each high voltage bus section and have it locked;

c. Turn off all systems of heating temper ature measuring/controlling and ash level controlling;

d. Keep in operation the rapping and discharge systems until all the smoke and dust are removed from within the ESP;

e. Open all inspection doors to cool the ESP off;

f. Turn off the main power switch (with the exception of lighting);

g. Access to the ESP is possible after the high voltage parts are earthed and when there is lighting inside the ESP;

h. After maintenance is over, shut all the doors.

9.6 For operation of the elec tric portion, refer to “Electric Instructions”.

10. Maintenanc e and Troubleshooting of Equipment

To obtain the goal of long-term reliable operation of ESP with required collection efficiency. Professional personnel should be appointed do be is charge of ESP operation and maintenance. These people must know the ESP’s design, principies, functions and performance and are able to operate & to maintain the ESP and to troubleshoot.

During each shut-down of ESP, a general check should be made to clean its inside, to correct the deformed plates and wires, to clear the insulators of dirt, to measure the earth resistance and to eliminate all defects occurred during its previous operation Normally and ESP is to undergo a minor overhaul once a year, items of which includes the replacement of worn parts. Every third year (or based on the boiler overhaul schedule) an ESP is to undergo a major overhaul, during which a spring-cleaning is made inside the ESP and adjustment and replacement of defec tive or worn parts and components are made. Moreover, lubricants are to be changed at regular intervals.

10.1 Routine checks and maintenance

10.1.1 After entering the ESP, first check to see if there is dust accumulated. If yes, get rid of it.

10.1.2 Check the side panels, access doors and insulator compartments on top of ESP to see if there are phenomena of air leakage, condensation, corrosion or dust accumulation, If there are, eliminate them .

10.1.3 Check the motor temperatures, oil level in speed-reducers, shaft bearings and rapping hammers to see if they are in good order and if the hammers hit on the correct locations. Lubricate the moters as per manufacturer’s manual.

10.1.4 Sometimes the gas distribution screens may have dust accumulations or blockages somewhere due to low gas velocity thereon. Check and clean manually.

10.1.5 Check the emitting frames and discharge wires to ensure that they are not deformed and that there is no

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dust deposit.

10.1.6 Check the collecting plates and sheck bars to ensure that they are not bent and that there is no dust deposit.

10.1.7 Check the support insulators for possible cracks resulting from high voltage breakdown due to accumulated dirt and moisture. Clean the insulator and search for flaws by using a flashlight.

10.1.8 Clean the shaft insulators in emitting rapping shafts and search for possible flaws by using a flashlight.

10.1.9 With reference to the manufacturer’s manual, check the T/R sets to see if the functions of the contact switches, relays, heaters, instruments for temperature measuring and controlling, alarms, earthing devices, etc. are normal. Eliminate the defaults if there are any.

10.2 Analyses of common troubles

10.2.1 Breakage of discharge wires

During ESP operation, if one discharge wire is broken, short circuit may happen with the result that a whole electric field is shut off and that there is a loss of ESP efficiency.

Some ESPs use stainless steel spiral wires. It should be pointed out that these wires will become weak under the following conditions:

a. There are folding points on the wires, which have been unnecessarily bent;

b. During erection, the wires are overstretched with the result that insufficient wire tension leads to electrocorrosion that breaks the wire;

c. Scratches on the wires easily lead to wire breakage. Special care should be taken to the protection of the wires during their mounting and replacement and the use of tools;

d. Electrocorrosion will also happen when there is loose contact between the wire and its end hook tubes;

e. Chlorides such as salt, ammonium chloride, etc. will corrode away discharge wires and must be dept from contacting the wires during trans portation and storage of the wires.

10.2.2 Rapping devices, if out of order, will result in heavy dust accumulation on both collecting and emitting systems, decrease of operating current, increase of sparks, corona blockage and short circuits in electric fields. Check the rapping devices both electrically and mechanically and solve any troubles so as to resume rapping.

10.2.3 Broken insulators

Insulators include support insulators for emitting system, shaft insulators for emitting rapper drive and feed thru insulators for high bvoltage connection. During the start-up period of the boiler, if there is oil-firing for a time longer than usual or if there is poor thermal insulation due to dldc tric heater out of order, there would be bust and moisture concentrated on the surface of the insulators, resulting in decrease in their superficial concentrated on the surface of the insulation resistance, and under high voltage circumstances, there would be breakdown, Also an insulator will crack due to uneven heating. In both cases, the damaged ins ulators need replacing.

10.2.4 Short-circuit caused by dust blockage in hoppers or dust deposit in electric fields

Heavy dust deposits in electric fields are usually caused by dust blockage in hoppers or failure of dust discharge system. Dust adherence or “bridging” in hoppers due to hopper heaters breakage and hence poor thermal insulation and/or huge amount of dust piled in hoppers and even in electric fields caused by failure of dust discharge system will inevitably result in electrical short-circuit in electric fields.

10.2.5 Defects of high voltage T/R sets

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10.3 Analyses of comprehensive defaults and their solutions No. Defaults Possible Causes Remedies

1. Large secondary current, secondary voltage won’t rise or even approaches to zero. Repeated trips after the HV switch in turned on.

(1) Possible earthing of emitting parts by foreign conductive material.

(2) Short-circuit between opposite electrodes caused by broken wires.

(3) Short-circuit in the HV loop. (4) Somewhere an insulator is heavily contaminated and hence

broken down

Remove the foreign mater ial. Replace the broken wires. Repair the loop. Clear the insulators of dust and condensation and replace the broken one.

2. Voltage won’t rise but current is small; OR severe flashover occurs resulting in a trip after voltage goes up (with large secondary current)

(1) Failure of insulator heating resulting in condensation on insulator surface, hence decreasing the insulation property and surface ereepage; OR gas temperature in ESP is lower than dew point, resulting in the same sequences as above.

(2) Heavy dust deposits on both collecting and emitting systems, causing their distance shorter.

(3) Too wide voltage distance. (4) Poor welding in casing or doors not sealed well, resulting in cold

air rushing in to deform the internals and to decrease the voltage distance.

(5) Internals swinging caused by impacts from uneven gas flows, resulting in severe flashover at low voltage.

(6) Full hoppers. Dust close to or touching emitting system. Resulting in reduced insulation property between opposite electrodes.

(7) Low output voltage from T/R (8) Big voltage drop in other parts of the loop (as with poor

earthing).

Repair or replace the heating elements .Clean the insulators. When gas temperature is lower than its dew point, the equipment can’t be put into operation. Repair the rapping systems. Check and adjust it. Make repair welds in the casing and tighten the doors. Adjust the uniformity of gas stream. Make the ash discharge/conveying systems work properly, clean dust blockage in hoppers and check hopper heaters. Check the system loop

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No. Defaults Possible Causes Remedies

3. Irregular changes in secondary current. Dust deposits on electrodes and sparkover occurs where the voltage distance is smaller.

Remove the dust.

4. Cyclical changes in secondary current. The remaining par t of a beoken discharge wire swings. Replace the broken wire

5. There is secondary voltage but no or very little secondary current.

(1) Excessive dust loading causing corona blockage (2) Severe dust depostis on collecting and emitting

systems. (3) High ground resistance and poor high voltage loop. (4) Broken circuit in the measuring loop of ampere

meter in HV loop. (5) Poor contacts between HV outlet and elec tric field. (6) Point of millimeter gets Stuck.

Improve the technological process to reduce dust loading in gas . Intensify rapping and remove dust deposits. Reduce the ground resistance to the specified value. Rectify the broken circuit. Check the connections and make them in full contact. Repair the meter.

6. Too many sparks. Wet air leaks in through access door, damp gas from leaking boiler or dirty insulators

Take corresponding corrective measures.

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No. Defaults Possible Causes Remedies

7. Low collection efficiency (1) Too big voltage distance. (2) Uneven gas distribution, gas screens blocked by dust. (3) Excessive air in leakage resuling in changes in operation

conditions. Increase of gas velocity, decrease of temperature, weak charging possibility of dust particles, etc.

(4) High resistivity of dust, backcorona may exist, slow charge neutralization in dust layers on electrodes and rapping unable to dislodge them due to s ignificant adhesive.

(5) Unstable HV power source of poor quality, decreased or zero sensitivity of voltage auto-adjusting system resulting in low working voltage.

(6) Conditions of gas entering the ESP do not agree with the original ones resulting in changes of operation conditions.

(7) Mechanical problems such as abnormal rapper. (8) Gas flow by-passes due to fallen gas baffles in hoppers.

Adjust it, Remove the dust, OR replace the gas screens. Make repair welds where there is air in leakage. Condition the gas quality Repair of replace the power source. Collection efficiency is to be calculated by using correction curves to the actual operation conditions Repair as needed, if rapping is not sufficient, replace with heavier hammers. Check to solve the problem.

8. Stuck ash discharge device, OR tripped safety device

(1) Hammer dropped (2) Foreing matters in discharge mechanism. (3) Broken chain in case a drag chain conveyer is used.

Shut down the equipment to r epair.

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10.4 Common electric defaults and their remedies; (Refer to electric manufacturer’s instructions for details.) No. Defaults Possible Causes Remedies

1. Control out of order (1) Primary power source failure. (2) T/R failure, T/R insulator broken down, HV switch contact

arcs, HV system creepage or short-circuit, insulator contaminated.

(3) Defaults in control system.

Repair or replace. Ruguarly record the readings on the metres, find as early as possible the unsual readings and defaults .

2. T/R output out of control. (1) Thyistor broken down. (2) Disappeared feedback.

Replace. Check related elements and loops.

3. Control and main loops do not work

(1) Safeaty interlock not in place. (2) Broken closing winding and loop. (3) Poor contact of auxiliary switch.

Check the access doors and cubicle doors for their closure. Check the line and replace the winding Repair the switch.

4. No lamp indication on panel when energized.

(1) Poor contact of loop elements . (2) Burnt lamp. (3) Burnt fuse.

Check the line and loop elements . Replace the bulb. Replace the fuse.

5. No indication of meters on panel During voltage adjus tment.

(1) Faults inside the meters. (2) No outlet impulses. (3) Broken quick-break fuse. (4) Open circuit in thyristor element. (5) Broken sampling loops for AC & DC. (6) Poor contact of change-over switch for measurement in AC

voltmeter

Check and calibrate the meters. Use an oscilloscope to determine the amplitude and number of outlet impulses. Replace. Replace. Check the secondary line. Check and repair.

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No. Defaults Possible Causes Remedies

6. There is signal on flashover indicator but no corresponding actions on other meters of the pand.

(1) Foreing interference. (2) Signal transform is blocked by flashover and failed elements .

Check the shield earthing status. Add a by-path and replace elements.

7. Secondary voltage won’t rise by itself upon a flashover, but initiates an alarm.

(1) Excessive width of the first blocking pulse upon the flas hover. (2) The given value of rate of voltage rise+△u/△t is too low.

Change the parameter to adjust the pulse width. Enlarge the given level.

8. During on load voltage step-up, there is normal voltage but zero current.

(1) Open circuit in current sampling loop. (2) Internal line breaks in the ammeter.

Check the secondary line. Measure the sampling voltage.

9. During voltage step-up, primary voltage adjustment is normal, but secondary voltage exists and disappears alternatively and is accompanied by noise of discharge.

(1) Open circuit and false soldering point in T/R secondary winding and s ilicon stack.

(2) Insufficient safety distance from HV inlet to ESP casing. (3) Open circuit in DC sampling oltage div iding loop.

Lift the T/R core for checks and eliminate the defaults . Check and relocate the HV inlet. Lift the T/R core for checks and repair.

10. Tripping of alarm for oil pressure; flavour of ozone from T/R

Breakdown of T/R secondary winding minor bridge in silicon stack.

Lift the T/R core and replace the damaged par ts.

11. Tripping and alarm of oil level signal

T/R oil level below the oil lower limit. Make troubleshooting and add oil to s uitable leel.

12. Tripping of alarm for oil pressure during operation

Gas in gas relay. Open the discharge valve to get rid of the gas.

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10.5 Replacement of spiral wires and support insulators 10.5.1 Replacement of spiral discharge wires

Discharge wires are the heart part of an ESP. They set off electric energy to the gas, and function in an adverse environment. Under high voltage conditions there would be flashovers and arcs, each of which is a kind of electro corrosion to the discharge wires. For spiral wires, when they are rapped, they will vibrate in the way strings on a musical instrument will do. Therefore, after long service the spiral wires may break due to fatigue (but the rate of breakage is very low). If a spiral wire breaks, it will lean against one of the adjacent collecting plates and short-circuit will happen, resulting in the shut-down of the related bus section. In such a case, the broken wires must be replaced.

During the replacement of spiral wires, in addition to the five points of attention as described in 10.2.1 abov e, follow the steps below:

a. Put the upper end hook of the spiral wire into the hanger r ing. b. Connect the other end hook of the wire to the special stretching tool and pull down gently by holding the rope

on the tool. By doing so, be sure to let the spiral wire turn freely. When the wire is stretched to a point of 200mm to 300mm away from the lower hanger ring, manage to put the hook into the ring by hand. Special care should be taken to the following: A. Should a spiral wire be stretched beyond its length as hung, it should be discarded. It is never allowed

to squeeze/compress an overstretched to its “ original” status for re-use. B. Do not pull the wire directly by hand as this will cause uneven stretching of the wire, resulting in easy

breakage. C. The spiral wire must be hung between the two corresponding hanger rings of a support frame. 10.5.2 Replacement of broken support insulator 10.5.2.1 dismounting a. Remove the top cover of the insulator compartment. b. Use a straight ruler to measure the distances fron the tie rod to the compartment top cover and the walls and have them recorded (or written on walls); c. Insert the lifting tool through the bushing and hook on to the upper support beam of the emitting frame; d. Turn the nut on the lifting tool to raise the emitting frame to let loose the support insulator. Unscrew the nut on the tie rod, remove the top washer and dismount the broken insulator. 10.5.2.2 Mounting a. Check and clean the top and bottom w ashers of the insulator; b. Check to see if the packing material is in good order and in place; c. Mcunt the new insulator in the reverse order of dismounting; d. Check the location of the tie rod, be sure that it is in the exact position as it was before the replacement of insulator. 11. Quick-wear parts and Spare Parts provided with Equipment (Type and quantity may vary from case to case.) a. collecting plate; b. Discharge wire; c. Hammer for collecting rapping; d. Hammer for emitting rapping;

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e. Plain bear ing; f. Major and minor pin wheels; g. Support insulator; h. Post insulator; i. Shaft insulator; j. HV feedthru insulator; k. Tubular electric heaters of different ratings; l. Sealing washer; m. Standard fasteners; n. Spare parts as specified by electric manufacturer.

12. Special Tools F-model ESPs should be equipped w ith lifting tools for emitting frames For ESPs using spiral wires and Huck rivets, the following special tools should be provided:

a. Huck rivets’ hydraulic fastening device (the ownership goes to the manufacturer); b. Discharge wires’ stretching tool.

Annex A

ELECTROSTATIC PRECIPITATOR—PROGRAM OF COMMISSIONING (For Reference) A1 Contents of commissioning Good installation quality is a must for an electrostatic precipitator (ESP) to achieve its expected efficiency. And commissioning after ESP installation is an indispensable means to check and ensure the installation quality. During commissioning, usually the following operations are to be made:

a. Check and test the ESP parts and components ; b. Test the air tightness of ESP; c. Check and adjust the installed ESP; d. Check and debug the ESP LV control loop; e. Check and debug the ESP H V control loop; f. Com missing of all ESP rapping systems and sah discharge drives; g. Energize and test all ESP electric heaters; h. Electric field on-load test without gas inside ESP (cold test); i. Whole ESP on-load test (hot test) Note on gas distribution test:

Since the results of insitu gas distribution gests are better than those of model tests, it is specified that no gas distribution adjustment test is to be carried out insitu.

A2 Preparations and safety measures before commissioning A2.1 commissioning of ESP should out by the installation contractor with attendance of representatives from the construction unit, manufacturer and owner . A general director and persons in charge of various commissioning items should be appointed. Plans for the commissioning (organization, directions of how to tackle the problems,

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how to record the problems, their resolution and other data, how to make the commissioning reports and whom to send such reports, etc. should be reached. A2.2 commissioning personnel should be familiar with the equipment instructions and other technical data so as to have necessary knowledge of the design of the equipment and its sub-systems and to perform the commissioning work according to the program in respect of items, methods, procedures and requirements of commissioning. A2.3 Get everything ready for the commissioning, including the following items:

a. 1 two-wire oscillometer; b. 1 electrostatic voltmeter, 100KV c. 1 didital multime ter, DT830 d. 1 pincerlike galvanometer, 1-5A; e. 1 each of 2500V megger and 500V megger ; f. 1 voltmeter, 600V, degree 0.5; g. 1 double br idge, degree 0.2; h. 1 three-winding autoformer, 2KVA, 8A; i. 1 set of common elec tric debugging tools; j. 1 set of incandescent bulbs with dummy load of 220V, 100W *2(self-made); k. 1 analog s ignal transformer (self-made); l. 1 set of 2-section insulating rods, 10KV (for discharging electricity); m. Lot of warning signs and safety railing (self-provided); n. Lot of plastic-insulated multi-core flexible wire for test connection (self-provided) o. 1 pair of powerful walkie-taldies (for communication at high altitude) .

A2.4 commissioning coordinators; General director: 1 person Operator: 2 persons Inspector/measurer: 2-3 persons Adjuster: Mechanical 2-3 persons Electrical 2-3 persons Liaison: 1-2 persons

Total 10-14 persons A2.5 Some confirmations

a. confirm the availability of utilities (water, compressed air, electricity, etc.); b. Confirm the availability of power source oil supplying releasing devices, fire-fighting system, etc; c. Confirm the insulation resistance of the main loop; d. Confirm the procedural inspections of the control loop, etc.

A2.6 Records of the results from inspections and tests are valid only after they are signed by representatives from the manufacturer, the installing company and the owner. The same applies to the summary report after the commissioning is completed. A2.7 For safety measures, Standard JB6407 should be abode by.

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A3 Inspection and test of ESP parts and components . A3.1 Check the main insulating elements in the HV net for their voltage endurance. Such elements are: HV isolating switch, support insulator, shaft insulator, feedthru insulator, etc. Tool: 2500V megger. Result: The insulation resistance should be greater than 100MΩ. A3.2 Check the gas relay of HV T/R and release the gas inside it before the T/R is assembled. A3.3 The HV isolating switch should be highly operative, can be exactly in place and the contacts can open and close flexibly. A3.4 Check the cable ends to see that there is no oil leakage. A3.5 HV silicon T/R should be checked for the following items:

a. The insulation on resistances between the HV & LV windings and the iron core & ground and between the HV and the LV windings should exceed 2000 MΩ;

b. Measure the insulation resistances between the bolt through the core and the iron core & ground; c. Measure the DC resistances of HV winding, LV winding and HV reactor, and compare the measured values

with the shop ones. The deviations can not be greater than ±2%; d. Measure the standard values of the resistors for current and voltage sampling, with deviations less than

±5% of the standard values; e. Measure the forward and backward resistances of each bridge arm and compare them with the values of

the arm in the same bridge arm and compare them with the values of the arm in the same bridge. The difference should be dept w ithin 10%;

f. Check toensure there is correct connection in the capacitance-resistant absorbing voltage balancer; g. Take samples of insulating oil for voltage endurance test. Take the average value of five tests, which should

not less than 40KV standard oil cup. A3.6 Before commissioning, the HV silicon T/R should undergo induced Voltage endurance test. Use a voltage regulator to step up the voltage from zero. When the input voltage is 380V, the output DC voltage should be more than 80KV for 1 minute without any abnormal noise. Record the secondary voltage and current. Make measurements on the designed reference tap and, at the same time, check the ratio of transformation on each regulating tap, The ratio error should be less than ±2%.

A3.7 Prior to commissioning, Check the reactor for: a. The insulation resistances between the bolt through the core and the iron core & ground; b. The DC resistances of winding and each tap; c. The insulation resistace between the winding and ground; d. If possible, the magnitude of induc tance of the reactor.

A3.8 If HV power cable is used to transmit the HV output from the silicon T/R, the cable should undergo the following tests;

a. Cable oil strength test: the one-time break-through voltage should not be less than 35KV standard oil cup;

b. Cable DC leakage test: Use a 2500V megger to measure the insulation resistances of the HV cable both before and afler the

tests; The test voltage applied to ESP DC cable for voltage endurance test is 2 Ue (twice the rated voltage ) for

ten minutes;

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If other kind of power cable is used as a substitute, the criteria of applied voltage and duration should be per relevant artices in Chinese standard GBJ232-82,《 Regulations of Electric Construction and Acceptance: Chapter 17 Standard for Electric Cross-connecting Tests》.

During the tests, apply voltages 0.25-, 0.5-, 0.75- and 1-fold in steps for 1 minute each. Record the values of leakage current. When measur ing, get rid of the influence of other currents.

A3.9 The appearing of one of the following phenomena during the cable DC leakage test indicates possible defaults in cable insulation, which should be found and t ackled;

a. Very unstable leakage current; b. Leakage current rises sharply as the rise of test voltage; c. Leakage current rises as time goes by.

A3.10 Measure the thyristor for its minimum triggering voltage and current, minimum maintaining current, the average forward and backward leaking currents, etc. A3.11 Measure the value of damping resistance and ensure that the measured value does not exceed the shop value by 2%. A3.12 Calibration and setting of relay protection

a. Routine calibrations of both AC and DC relays should be made in ac cordance with 《calibration Regulations of Relays》issued by the Ministry of Machine-building Indus try. The overcurrent on the AC side of silicon T/R should be set to 1.05 to 1.1 folds Ie and tripping should have a delay of 0.5 seconds;

b. Thermo-relays and temperature relays should be calibrated on a regular base. Temperature limits for the silicon T/R should be set as per manufacturer’s specifications. Normally a high-temperature warning will be given at 70℃ and a trip alarm be initiated at 80℃;

c. The setting values of the temperature-controlling relays for ESP heaters are to be provided by the relay manufacturer and to be set by the construction unit;

d. The relays for liquid levels should satisfy the range of temperature variation during operation and shut-down of ESP and the signals should actuate correctly;

e. Calibration of varistors for over-voltage protection and autovalve lightning arresters should be made as per manufacturers’ technical quotas;

f. Measure the earth resistance of ESP grould be checked to see that they are in good or not more than 2Ω. A3.13 All insulators equipped on the ESP s hould be checked to see that they are in good order and flawless. A3.14 Prior to their mounting, all insulators should be tested for their insulation resistance and AC voatage endurance, which should be up to the manufacturer’s specification. (Normally the insulators should withstand 100KV for 1 minute at amient temperature.) A3.15 Prior to their mounting, all motors for rapping, dampers and ash discharge should be inspected and bear ings greased as per specification. A3.16 For electric heaters, the model and par ameters shown on the nameplates must comply with the design requirements. Prior to mounting, first make visual inspections to see that they are in good order and use a 500V megger to measure their insulation resistance, which should exceed 50 MΩ. A4 Air-tightness test: After ESP is installed but before thermal insulation is applied, the ESP should undergo air-tightness testing. This is normally done by means of smoke bombs with procedure as follows: A4.1 Purpose: To check the air-tightness of the ESP proper by means of the smoke-released from model 65-1 military smoke pots. A4.2 Preparations:

a. Block the ESP proper from the inlet and outlet flue ducts and seal the hopper outlets and access doors;

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b. For an ESP, each test needs 3 military smoke pots, of which 1 is spare; c. Fix an axial blower at the entrance of a designated access door; d. Get 2 or 3 gas masks ready; e. Get fire-fighting equipment r eady and in place; f. Make available 1 small tin of white paint and a few Chinese brushes; g. Organize 6 to 10 ins pectors and assign them to different locations. A4.3 Test procedure; A4.3 Test procedure:

a. place the smoke pot on ESP internal walkway; b. Ignite the pot as per the instructions of the pot, wait until the pot smokes properly when you can go out

and shut the access door. c. Switch on the axial blower to pressurize the ESP inside; d. Check wherever is needed and us e white paint to mark exactly where there is smoke leaking out; e. Open the access doors to get rid of the smoke from ESP inside, stop the axial blower and apply repair

welds where marked; f. Repeat the abov e test until the ESP casing is totally sealed with no leakage.

A4.4 Safaty measures: a. The igniter of the smoke pot must wear a gas mask beforehand; b. After the smoke pot is ignited, all operators inside the ESP should withdraw in time and the axial blower can

not be started before the access doors are covered; c. Fire-fighting devices should be available at job site. d. No repair welding should be made dur ing the smoke test. A5 Post-installation check and adjustment of ESP A5.1 Check and adjustment of centres of emitting and collecting electrodes:

a. In addition to the 100% inspection of emitting and collecting electrodes on the ground beford assembling, another 100% check and adjustment should be made af ter their installation;

b. Check the discharge wires piece by piece for their quality. If there are defects or, in the case of spiral wires, they are overstretched, the elec trodes should be discarded and new ones replaced;

c. Check the passage spacing at both ends of each gas passage; d. The voltage distance, i. e. that between the corresponding collecting

Plate and discharge wire, in any passage should be within the deviations set in Standard JB5910, which specifies the deviation of voltage distance is ±5mm when the collecting plate height H≤7m, and ±10mm when H>7m.

e. During the check and adjustment of voltage distance, take measurements of the distances between the outside wall of the horizontal square tube in the emitting frame and the outer side of the catch space on the collecting plate;

f. Make 5 to 9 measurements along the height of each passage. Which means one measurement is taken on each horizontal square tube of the emitting frame. Use a special “T” shaped measuring tool; Keep records of the results. Adjust where the deviation is exceeded;

g. Adjusting forces should be applied gently h; h. Methods of heating for adjusting are forbidden.

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A5.2 Deburr the emitting and collecting electrodes parts, The distances between high potential parts and low potential ones should be kept greater than the voltage distance between emitting and collecting electrodes. A5.3 All bolts on collecting curtains, emitting frames and their rapping devices should be tightened and welded dead. A5.4 Impacting points of the hammers on the anvils are as required and shafts and hammers can turn without jamming. A5.5 No foreign objec ts exist in electric fields. A5.6 Motors for damper, speed reducer, ash discharge, etc are in good order. Chains have proper tension. Oil/grease has been applied wher e needed. A5.7 Connections of dampers, gas baffles, I.D. fans, ash discharge system, roof panels and access doors are tightly sealed. A5.8 Reliable welds are applied with no false or missing welds, hence having good tightnes s. A5.9 All insulators are clean and dry and forces applied to them are evenly distributed. A5.10 Earth resistance of ESP proper is less than 2Ω and that of electric equipment is less than 1Ω. A5.11 Insulating resistance of the high voltage network as measured with a 2500 V megger should be greater than 100MΩ. A5.12 Connecting cable between the ESP casing and the positive pole of HV T/R should be in good order and firmly fixed. A5.13 Operating mechanisms in HV isolating switches are flexible and have correct positions. A5.14 Insulating resisance of all motors as measured by a 500 V megger should be not les s than 0.5 MΩ. A6 Check and debugging of ESP LV control loops A6.1 Energization test of drives for various systems and no-load trial run of the equipment are not to be carried out until the wiring check is made with good results. A6.2 Items to undergo energization test include alarm system, rapping loop, ash removing loop, heating and temperature-detecting loop. A6.3 Before energization, detach the connecting wires of each panel to ESP LV elements at the terminals. After energized, turn on the power switches on each panel and there should be indication on the menters for power voltage. A6.4 When the alarm system is initiated manually and automatically. The instaneous and delayed sigals of both sound and light should have correct actions and can be released reliably. A6.5 Methods and requirements of checks for rapping loops are as follows;

a. Trial run: Disconnect the power line to the motor within the panel, Switch on to energize and switch off to deenergize three times manually to see that the contactor can close and open correctly and that the optical characters for signals meet the design requirements. Then trial run automatically in a time controlled mode. With certain fit value in equation of time, repeat the movement for value in equation of time sequences to see that the fitting of equation of time, the closing an opening of the contactor and the optical characters for signals are all correct and adjustable during field tests. By means of programmable control, initiate the program for three cycles to see that the equation of time and logical performance are correct without any disorder and that the equation of time and logical performance can be adjus ted during field test.

Deenergize to resume motor connection after the test is over. b. No-load test: Release the coupling and switch on to energize:

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In manual mode: After start-up, check to see that the motor rotates in the direction required by the control unit. Close and open for three times, and measure the values of starting current, no-load current and unbalanced interphase current. In auto time controlled mode/programmable control mode: Respectively perform for three time sequences and three cycles. The fitting of equation of t ime and logical performance should be correct. Deenergize to resume the coupling after the test is over with good results.

c. cold test run with rated loading: Sw itch on to energize. In manual mode: Record the starting current during test run and measure the threephase current and the maximum unbalanced current. Check the set values of thermal elements to see that they are normal after closing and opening for 3 times. Check the impacting points of the rapping hammers on their respective anvils to see that the pre-set margins arount the points meet the design requirements and that the hammers can tumble freely without ay phenomena of jammed hammer, dropped hammer or idle hammer. In auto time controlled mode: Rap for 3 cycles according to the design program provided by the manufacture to see that the programmed sequence and time sequence are correct without disarrangement. After both the mechanical and electric portions have passed inspection, continuous test rapping should be normal at least for 8 hours. A6.6 Methods and requirements of checks for ash removal and conveying loops: a. Trial run: Detach the motor power line from the lower end of the contactor and switch on to energize.

In manual mode: Close and open for 3 times to see that the contactor, signal and optical characters function correctly.

In auto mode: Under simulatrd ash levets, gear for 3 times to see that the inter locking is correct. Deengerize to resume motor connection afler the test is over with good results.

b. No-load test run: Release the load of as h removal devices and energize to turn the motor. In manual mode: Start the motor to determine its rotational direction. Measure the starting current of the motor and its threephase current. The mounting unit s hould agree with the signal indication. In auto mode: S imulate opening and c losing for 3 times. There should be correct signals and interlocking. After normal no-load test run, deenergize to resume the mechanical loading. c. Trial operation with ash removal mechanisms connected

In manual mode: Measure the starting current and threephase current during start-up and check the set value of current for thermal elements .

In auto mode: Make simulated start-up for 3 times and their operation should be proper. As for hot status ash level tests, they are to be made under actual operating conditions.

After the mechanical and electric portions have passed inspection, continuously run the devices for 8 hours without jamming.

A6.7 Methods and requirements of checks for loops of heating undercurrent alarm and temperature-detecting a. In manual mode: Energize for 30 minutes and measure the current. Check the set value of thermal

elements. There should be cor rect signals and mounting unit. b. When an under current alarm is equipped in the heating loop, if any heater within the loop is cut off manually,

the undercurrent alarm should actuate. c. In time controlled mode: Perform simulated opening and closing twice, when the contactor and signals

should actuate correctly and the control range of temperature should meet the design requirements . After

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being energized for heating, the heater will stop functioning when the temperature reaches the upper limit and will resume function when the temperature falls below the lower limit.

A6.8 The debugging of LV control loop should be made with reference to the debugging instructions from the manufacturer. A7 Check and debugging of ES P HV control loops A7.1 Test run of the control loop in HV silicon T/R

With the wiring on the LV side of T/R detached, test the local and remote switching functions (ON & OFF), gas relay, overcurrent relay, temperature protector tripping, alarms for liquid level and temperature, inter locking for air cooling etc. Their light, sound or signal must be corret.

A7.2 Debugged items in HV control loops include the pre-setting of the limiting parameters of controlling inserts and open-and closed- loop no-load apparatus for debugging use. A7.3 Before debugging, c heck the HV T/R control loop for

a. correct wiring both ins ide and outside the T/R as required in the principle diagram; b. Agreement of the elements with the specification of regulations concerned; c. Various adjusting knobs being in their starting points.

A7.4 The debugging of HV T/R control loop should be made according to the debugging peogram and normally in two steps: open loop and c losed loop. A7.5 Open loop debugging:

a. Open loop debugging can be made on a simulator or on the control cubicle with adjustable control inserts and static parameters for each link. When testing on a control cubicle, detach all the lines to the silicon T/R in the main loop and attac h 2 incandescent bulbs 220V, 100W each as dummy lad instead;

b. After energization, measure the secondary voltage values from thte power transformer and control transformer. The values should meet the des ign values.

c. Put in the voltage-stabilizing inserts and measure the stabilized DC output voltage for the purpose of voltage stabilization test. Keep records of the AC fluctuations and gradually put in the other inserts ater the AC fluctuations are acceptable;

d. Measure and record the static voltage at each measuring point. Observe, with an oscolliscope, the actual wave on the measuring point and compare it with the standard wave. IF the voltage value is within the specified range, the waveform should be similar without deformation;

e. Measure the ranges for set values of voltage step up by both manual and auto adjus tments; f. Measure the adjustable ranges for rates of voltage step up and step down; g. Pre-set the threshold voltages of flashovers and under voltage loops ; h. Measure the accelerating time dur ing voltage step up with blocked output pulse width and the time for under

voltage delay tripping; i. Measure the amplitude and width ( or number of pulses ) of the triggering output pulse and see that it is

corresponding to the phas e of the synchronizing signal; j. The thryristor should be fully open when manual and auto voltage step up checks are made. A7.6 Closed loop debugging: w ith silicon T/R load and secondary wiring connected:

a. Step up voltage manually. Use a HV static voltmeter to check the DC voltage shown on the control panel under rated voltage;

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b. When the voltage rises to its rated value, check the feedback sampling value of the DC voltage. Plot the V-I characteristic curves of the T/R under adjustable voltage conditions. Record the data and waveform on key measuring points. The amplitude of D C output waveform should be symmetrical;

c. Add an earthing line and check the flashover properties manually. Record the data and output waveform under flashover conditions on the measuring points. Time and condition of flashover blockage should meet the apparatus’ nominal figure and principle of flashover;

d. Check the property of transient short circuit at flashover. The logical performance circuit should actuate correctly. Record the AC input voltage and current. The DC input current should be less than the rated current. Record the data and w aveform on the measuring points;

e. Check the property of short circuit at no flashover conditions, first manually and then automatically. Manually make a direct short ciruit to step up the current from zero to the rated value or automatically step up the current in increments. When the given value reaches its maximum, the short circuit current should not exceed its factory-measured value. Record the data on the meas uring points.

A7.7 The debugging of HV control loop should be made with refernce to the debugging instructions from the manufacturer. A8 Commissioning of the dr ives for ESP rapping systems and ash remoal devices. A8.1 Purpose Before the ESP is put into operation, an individual test run should be made to the rapping systems and ash removal devices so as to guarantee ESP ’s safe operation in future. A8.2 Preparations

a. Make an overall inspection of the rapping racks, rapping shafts and hammers; b. All parts and components should be free of burrs and weld splashes; c. The installed dimensions should be as per those shown in the appr oved drawings; d. The rapping shafts can be turned manually ; e. For collecting rapping, the hammer should be hitting within ±4mm from the center of the anvil, and two

adjacent hammers should be at an angle r equired by approved drawing; Check the reducing gear for oil level and oil plug; Check the shafts for tight seal; Check the nuts and bolts to see that they are tightened and w elded dead;

f. For emitting rapping, the major and minor pin wheels must have good engagemen t; Shaft insulators should be c lear of dirt; Check the shafts for tight seal; Check the angle included between two adjacent hammers to make sure it is as required by approved drawing.

g. Check of rapping system for gas distribution screens is the same with that for collecting rapping. See Point “e” above.

A3.3 Trial run A3.3.1 Collecting rapping:

a. Run the rapping motor with no-load connected for 2 hours and see that there is no excessive heating, vibration and noise;

b. Make on-load test run and see that nothing is jammed;

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c. Make sure the motors rotate in the correct direction; d. Start the shafts ans press down the “FAULT” button when the motor turns at full speed. And the shafts

should continue to rotate for less than a turn and stop. Repeat the abov e method and mak e sure there are no errors before the power can be switched on to further run the rapping system;

e. Keep the rapping system in operation for 1 hour. Stop the system to make an overall check of it. Its installation is considered to be acceptable if no abnor mal phenomena ar e found.

A8.3.2 Emitting rapping Refer to A8.3.1 above. A8.3.3 Gas distributor rapping Refer to A8.3.1 above. A8.3.4 Ash removal devices

Refer to A8.3.1 above. A8.4 Final cleaning

a. Detach the power source of all the motors and lock the local switches; b. Holes in ESP casing for penetration of rapping shafts must be tightly sealed; c. Get rid of any odds and ends left during test run.

A8.5 Safety measures a. All the motors must be operated by professional personnel; b. No adjustment or maintenance of the equipment is allowed to make during its operation; c. Sufficient lighting should be available when ins pections are made ins ide the ESP; d. Get fire-fighting facilities ready.

A9 Energization test of ESP electric heaters A9.1 Before the electric heaters are mounted, check to see if the type and parameters shown on their name –plates comply with the design requirements, Make voltage endurance tests and insulation resistance measurements of the heaters. The applied voltage is 2000V and the insulation resistance should not be less than 50MΩ. A9.2 Should there be a long interval of time from their mounting to their use, measure to see that the insulation resistance is up to standard before the rated voltage is applied to the heater s. A9.3 Energize the heaters and check to see :

a. If there is broken circuit; b. If the speed of temperature rise is proper; c. If the range of temperature control is correct.

A9.4 Tests of electric heaters with thermostat autocontrol will vot be made until the ESP is fed with normal hot flue gas. A10 Cold no-load tests of ESP with air A10.1 Cold no-load tests of ESP with air can be made after the HV silicon T/R passes no-load performance debugging. A10.2 Sequence of cold no-load test: first put in service the LV equipment (especially the heating loop), and after they pass the inspection, put the HV system into operation for debugging. A10.3 Before the debugging of the H V silicon T/R in cold on-load air tests the LV system must satisfy the following:

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a. Rapping systems are in normal operation and rapping sequence in accordance to designed program. Rapping time and c ycle meet the set values;

b. Ash removal and discharge systems are able to function well with ash removing time and delay meeting the set values;

c. Commissioning of devices for temperature measuring and indicating is finished with correct indication of measured temperature;

d. The actual temperature inside the ESP should be in conformity with the indicated temperature on the corresponding point is the control panel.

A10.4 Debugging proc edure for voltage step up in electric fields with cold air only: a. First step up the voltage under conditions that neither rapping system nor I.D. fan is put into use. b. Then step up the voltage under conditions that no flue gas is led in the ESP but both HV and LV

equipment is put into use. A10.5 The purposes, conditions and methods of voltage step up tests in air for ESPs should follow the specifications stated in Article 5. 4 of standard GB/T13931, Normally the test begins from the ESPs last field and goes through the middle field(s) till the first field. The methods and requirements are as follows:

a. Before making voltage step up test in individual electric field, first energize the heating systems for insulator compartments. Open the door to the insulator compartment, get rid of the moisture inside the compartment and on the insulator, then close the door. Turn on the HV isolating switch to put the electric field into operation. Use an oscilloscope to monitor the waveform of the feedback signal for current. Put the voltage measuring switch in the position of “PRIMARY VOLTAGE” and the operating selector switch in the position of “MANUAL STEP-UP”. Set to maximum the current limit knob on the adjuster panel in HV control cubicle. Press the “START” buttons and both current and voltage will rise slowly. At this point, keep hold of the operating switch and watch carefully the points of various meters on the control panel and the current feedback waveform in the oscilloscope, lest the HV system is damaged if any protective link is out of order. Druing normal voltage step up, corresponding indications will be shown by various meters and the current feedback waveform will be symmetrical double half-waves. When the current rises to 50% of the rated current, both current and voltage will stop rising due to the effect of current limit. In such a case, set the operating selctor switch to “AUTO” position and gradually adjust the current limit towards minimum. If there is no flashover in the electric field, it is able to adjus t the output current to the rated value.

b. At the initial stage of voltage step up, if there is fast rise in primary and secondary currents, but no indication on the voltmeter, there must be short circuit in the secondary loop. IF there is fast rise of voltage and indications for primary and secondary voltages, there must be open circuit in the secondary loop, And if there are indications for secondary voltage and current, if the primary current is greater than rated value, if the primary voltage is about 220V and if the ignition angle is more than 95%, then there must be breakthrough in one s ingle thyristor element or in one group of the H V thyristor stack.

Should any of the above –mentioned phenomena occur, shut down the equipment at once and make trouble-shooting before resuming the voltage step up tests;

c. During the voltage step up test in empty field, if the secondary voltage is much lower than the rated value, there will be flashover in HV network or in electric field. If no flashover occurs in HV network or in electric field, but the flashover-controlling links in HV contric field, but the flashover-controlling links in HV control system actuate, there will be “false flashover” phenomena. At this point, make adjustments on the taps of the T/R of of the reactor and on the controlling unit;

d. For voltage step up tests, calibration should be made to various instruments and meters. A HV electrometer can be used to measure the outputs of a HV T/R. To facilitate the calibration, the readings of secondary voltmeter can be checked when the secondary voltage rises to 40KV to 50KW without flashover. At the same time, use a multimeter to measure the DC voltage of feedback current signal, Since the sampling

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resistance of current feedback is given, the indications on secondary ammeter can be calibrated according to Ohm’s law;

e. Adjustment of taps on HV silicon T/R and reactor can be made based on the waveform of current feedback. Its principle is as follows: adjust the tap to obtain smooth and round waveform in the feedbac k current signal and a maximum ignition angle, I,e. to make the waveform close to the ideal one as far as possible.

A10.6 Parallel power supply during no-load voltage s tep up test: The choice of capacity of HV silicon T/R depends on the current densities on collecting plate and

discharge wires and the value of breakthrough voltage. Since there is great current density in the air during no-load voltage step up test, the energizing capacity of a single HV silicon T/R is not enough for a single electric field, i.e. the secondary current is blocked after it reaches its rated value and the secondary voltage can not reach the magnitude to break down the electric field. In such a case, 2HV silicon T/R sets of equal capacity can be paralleled to energize one and the s ame electric field with details as follows: a. Parallel energization must be based on the facts that each silicon rectifier has been qualified in the

debugging of and the same electric field, that the rectifier and the electric field are both free of defects. In the establishment of parallel energization, the two HV silicon rectifiers are connected in parallel energization, the two HV silicon rectifiers are connected in parallel after the damping resistance, either by a HV isolating switch to change the two rectifiers and the field to a connecting bus-bar, or by a wire that has a guaranteed discharge distance (at least 500mm above ground). During operation, start the two rectifiers simultaneously and use the “MANUAL STEP UP” and “STOP” functions from the operating selector switch to step up voltage in both units. If the sum of both risen currents does not reach the rated value, it is possible to continue the step up until there is flashover in the field. At this point, the secondary current is the step up until there is flashover in the field. At this point, the secondary current is the sum of currents from the two units and the secondary voltage is the average of secondary voltages from the two;

b. During no-load voltage step up tests, full-time personnel should be appointed to monitior the HV T/R silicon T/R against its malfunctions. When the HV T/R is located on top of ESP, the power cable for primary feeding is long. Therefore the primary side input voltage of the T/R must be measured and compared with that shown by the voltmeter on the control panel: if there is big difference between the two, make froubleshooting accordingly.

c. Keep records of the test data. Record the corresponding secondary voltage (after the corona initiating cvoltage) to the tiny secondry current. Record the secondary current corresponding to every gain of 5KV in secondary voltage as well as the primary voltage and current. Plot the V-I characteristic curves for each field, which should have nearly the same shapes, If the V-I curve of some field is different from others, make adjustments until everything is all right. For electric field using barbed wires and a voltage distance of 150 to 200mm, its secondary voltage may reach 55KV to 66KV or higher.

A10.7 Test run under conditions that no ulne gas is led in ESP but both HV and LV equipment are put into use. If conditions are available, make such a test run for 24 hours running. Make an over check of the

performance of all working loops and solve any defects thus found. A11 Hot on-load test run of ESP (72-hour operation) A11.1 After the ESP pases the tests as described above, the ESP can undergo hot gas test run if

a. The erection of ESP inlet and outlet flue ducts is finished. The boiler is ready for operation and the I.D. fans have been tested with satisfactory results;

b. The installation of ash removal and discharge systems is completed The water pumps for ash flashing have been tested and water volume adjus ted to proper extent.

A11.2 Before flue gas is led in the ESP, make sure that all the inspection doors are closed tight, that the LV heating system is turned on to raise the temperature in insulator compartments to above gas dew point. After flue gas is led in to warm up the ESP so that the insulation resistance of the electric fields will be increased to over 500MΩ, which can be measured with a 2500V megger.

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A11.3 At the beginning of boiler firing, HV equipment of ESP can not be put into service, otherwise the oily smoke entering ESP may cause explosive the oily smoke entering ESP may cause explosive burning and form corrosive films on ESP internals. The HV system can be turned on only when the ESP is 60% or more loaded and the boiler is fired by pulverized coal (not more than 2 oil guns in use). For boilers using gas to ignite, their safe operation regulations should be s trictly followed. To avoid explosion, the ESP HV system can not be put into us e before the boiler operation is normal.

Apply HV to each electric field in the same way as the cold air step up tests. Usually the breakdown voltage in the fields and the secondary current will be lower than those in cold teste. A11.4 Select the optimum operating mode and mak e the following setting:

a. The set undervoltage value should be less than the minimum c orona initiating voltage; b. The measurement of flashover threshold voltage should based on the flashover status in the fields. Adjust

the threshold voltage to make it input the blocking signal; c. Plot the V-I characteristic curves of each field and record the data and waveform on main measuring

points. A11.5 the multifunctional tracing silicon controlled rectifiers fhould be tested under cold air and hot gas operating conditions for their individual functions of spark tracing, critical spark tracing, peak voltage tracing, energization with interval- adjustable pulses, etc. plot the V—I curves under different conditions. Measure the data on each measuring point. Observe the waveform on each measuring point and see that the waveforms do not deform. A11.6 Adjust the spark rate for each field. Normally the rate for inlet field is 60-80 sparks/minute, for middle field(s) is 40-60 sparks/minute and for outlet field is 20-40 sparks/minute (or stabilized at higher corona power). The spark rate for high resistivity dust can be somewhat greater. The spark rate obtained after the measurement of ESP efficiency should be taken as the actual spark rate. A11.7 For control units with auto tracing function of flashover blocking time, simulating tests for the stepped features of flashover blocking time should be made. A11.8 Excessive dust loading of gas, too high gas velocity and uneven gas distribution will result in frequent flashovers in the fields and even arcs. In such a case, adjustments can be made to the sensitivity of arc quenching link, which, however, should not actuate upon nor mal flashovers. A11.9 To make the waveforms of current and feedback smooth and round, adjustments can be made on the primary tap of the T/R or on the reactor taps according to the actual operation status of each field during hot gas treatment. A11.10 Debugging of LV control equipment A11.10.1 Rapping loop. The main items to be adjusted are rapping cycle and rapping time. Ideal set values of the two are mainly obtained from the results of efficiency measurements or the inspection results for collecting plates and discharge wires during ESP shut-duwn, and usually after repeated adjus tments. A11.10.2 Adjustment of ash discharge time is based on the actual ash volume stored in the hopper of each field. Normally a hopper shoule have ash contained to one-third of its height. For ash transport enlongated time, the principle is that the ash in the conveying system, its fluching water volume must be adjustable to ensure efficient cleaning of ash deposit in the silo. A12 The accuracy of ESP commissioning should be comply the requirements set in Standard JB/T5910 or relevant technical agerrment. TRANSLATOR’S NOTE: This manual is the English translation of the original in Chinese. Should there be anything unclear herein. The Chinese version must govern.