SEM-9500E Flare Stack

DESIGN MANUAL

Preparation of Datasheet

for Flare StackSEM 9500E

REV. : 0

DATE : 2006. 8. 23PAGE 1 OF ii

CONTENTS

Page

11GENERAL

12PROJECT INFORMATION

13DESIGN CONDITION

13.1Flow Rate

23.2Pressure

23.3Temperature

33.4Allowable Pressure Drop (Line No. 16)

33.5Smokeless Type (Line No. 17~18)

33.6Purge Gas Composition, Flare Gas Composition (Line No. 19)

43.7Ignition Gas (Line No. 21)

43.8Pilot Gas (Line No. 22)

43.9Purge N2 (Line No. 23)

43.10Steam (Line No. 24)

53.11 Compressed Air (Line No. 25)

53.12Permitted Density of Poisonous Gas on the Ground (Line No.27)

53.13Max. Heat Intensity (Line No. 28)

64MECHANICAL DESIGN DATA

64.1 Burner Section (Line No. 34)

74.2Tip Section (Line No. 41)

84.3Gas Seal Section (Line No. 48)

94.4Riser Section (Line No. 5)

94.5Water Seal Drum (Line No. 9)

104.6Knockout Drum (Line No. 13)

114.7Air-Craft Warning Lights (Line No. 18)

114.8 Local Control Panel (Line No. 19)

114.9Platform, Ladder & Handrail (Line No. 20)

114.10Davit (Line No. 21)

125CONTROL

125.1Burner Ignition (Line No. 28~30)

126CODE & STANDARD (LINE NO.33~36)

127CONSTRUCTION

127.1Overall Stack Height (Line No. 39)

127.2Support Method (Line No. 40)

137.3Weight (Line No. 42~44)

138SITE CONDITION (LINE NO. 6~10)

139AREA CLASSIFICATION (LINE NO.11)

1310ELECTRICITY (LINE NO.12~13)

1311REMARKS (LINE NO. 16)

1412REVISION HISTORY

1GENERAL

This Guide does not include all the technical matter for flare stack design and indicates just how to make the process data sheet of flare stack for process engineer.

Basically, data sheet is made out based on project specification. The special requirement for process is filled up in "Notes"

The sample data sheet is shown as the attachment #2.

2PROJECT INFORMATION

From LINE NO 1 to LINE NO 7, project information (Customer, Location, Unit, Job No., Supplier, Req'n No., Item No., Service, No. Req'd) shall be identical to job instruction and especially, item number and service shall be same as equipment list.

Supplier and Req'n No. are not filled up by process department.

3DESIGN CONDITION

3.1Flow Rate3.1.1 Design (Line No. 9)

The maximum load among PSV Relief load summary (The maximum heat flux considering LHV and flow rate) is filled up. Sometimes, factor from dynamic simulation or experience can be applied.

3.1.2 Normal (Line No. 10)

Fill up the flow rate of fluid entering the flare header at the normal operating condition as like normal vent, intermittent purge and transition up-set condition. (Refer to "SMOKELESS TYPE")

3.2Pressure3.2.1 Design (Line No. 12)

This is for the design pressure of stack and 3.5 kg/cm2G can be applied unless there is client standards and project specification.

Minimum 3.5 kg/cm2G design pressure is for the preparation of flame arrester and labyrinth seal if necessary.


This can be changed by stack diameter which is decided by vendor considering allowable pressure drop.

3.3Temperature3.3.1 Design (Line No. 14)

Normal temperature + 25 OC

If it is higher than 343.3 OC or lower than -28.9 OC, Carbon Steel can't be used.

To avoid designing total stack with high temperature, the vessel is installed on the upstream of knock out drum.


It is not filled up with relieving gas temperature. It is filled up with real stack inlet temperature considering the outlet temperature of knock out drum.

3.4Allowable Pressure Drop (Line No. 16)

In general, 0.2 ~ 0.5 kg/cm2 is applied, calculated pressure drop is decided by vendor finally. (This value affect flare header line sizing.)

3.5Smokeless Type (Line No. 17~18)

In case of continuous flare load, fill up "Yes".

If the almost design flow rate is caused by the release from safety valve, only an amount of load can be treated with smokeless. If normal flow rate is unknown, 10~20% of design flow is applied in general.

If the gas which does not generate smoke is fed to flare in normal condition and the heavy hydro carbon gas which generates smoke in emergency condition, Fill up with "No" is possible in case that the environmental regulation allows non-smokeless flare.

Smoke suppression medium such as steam, air blower, water and gas can be used. Steam is used in general.

The requirement of steam pressure is about 5 ~ 10 kg/cm2 G and minimum 4 kg/cm2 G.

3.6Purge Gas Composition, Flare Gas Composition (Line No. 19)

The purpose of using purge gas is to prevent the air incoming to stack, confirm the positive flow of gas and prevent the flame flash-back.

Inert gas or fuel gas is useful. Gas composition is shown. N2 is used in general.

Flare gas composition shall be shown to decide low heating value and flame emissivity value.It's better to describe LHV if could. But, if gas composition is filled up, LHV is calculated by vendor.

Flame emissivity value is main factor to calculate the stack height. This value is shown on utility manual. The value which vendor suggested is no more than 1/3 ~ 1/2 of the value from SECL manual and other reference.So, stack height from vendor is much lower than the height calculated with API RP-521.

3.7Ignition Gas (Line No. 21)

Fill up the available pressure of gas for ignition of flare pilot.

Fill up the gas composition and condition. The same gas as pilot gas can be used.

Consumption per 1 time is suggested by vendor. It is possible to supply with cylinder.

3.8Pilot Gas (Line No. 22)

Fill up the available pressure of gas for continuous burning of pilot burner.

Fill up the gas composition and condition. The consumption rate is suggested by vendor.

3.9Purge N2 (Line No. 23)

Fill up the available pressure of purge N2.

Consumption rate is suggested by vendor.

3.10Steam (Line No. 24)

Fill up the available pressure of steam.

Steam is used for anti-freezing of water seal drum, vaporizing of knock-out drum, smoke suppression and tip cooling.

Consumption rate is suggested by vendor.

3.11 Compressed Air (Line No. 25)

Fill up the available pressure of compressed air.Compressed air is mixed up with gas which is used for the ignition of flare pilot.Consumption rate is suggested by vendor. It is possible to supply with cylinder.

3.12Permitted Density of Poisonous Gas on the Ground (Line No.27)

Fill up the limitation of sound level and environmental limit (the concentration at the ground level of contaminant) according to environmental regulation.

3.13Max. Heat Intensity (Line No. 28)

Fill up 300 BTU/hr-ft2 (Including solar radiation)" in general.

3.13.1 Distance from Flare Base (Line No. 30)

Fill up the distance from flare base to any places as like fence.

Fill up any one among 10M, 20M, 30M, and 40M.

3.13.2 Wind Speed (1) (Line No. 31)

Fill up the design wind velocity to calculate radiation heat intensity. If this value is unknown, fill up 10 m/sec.

Fill up max. Heat intensity in the blank. Fill up 1500 BTU/hr-ft2 (4000 Kcal/hr-m2) unless there is any special requirement from client or any regulation of the country.

1500 BTU/hr-ft2 : Heat Intensity in areas where emergency actions lasting several minutes may be required by personnel without shielding but with appropriate clothing. Allowable expose times are 5 minutes.

3.13.3 Wind Speed (2) (Line No. 32)

Present safety circle with the height calculated from design wind velocity as shown on the above at the normal wind velocity (the velocity exceeded 50% of the time) the design wind velocity to calculate radiation heat intensity. If this value is unknown, fill up 5 m/sec.In this case, fill up "500 BTU/hr-ft2 (Not including solar radiation)" for heat intensity.

500 BTU/hr-ft2: Value of permissible design level at design flare release at any location where personnel are continuously exposed.

4MECHANICAL DESIGN DATA

4.1 Burner Section (Line No. 34)

Fill up "To be supplied by Vendor".

4.1.1 Type (Line No. 35)

Fill up "Yes" normally.

4.1.2 No. Required (Line No. 36)

Fill up "By Vendor (Min. Two)". The design factors are tower diameter and turndown ratio.

3 burners are supplied in general if the diameter is higher than 14"

4.1.3 Ignition Method (Line No. 37)

There are two kinds of ignition, pressure ignition and atmospheric ignition.

Fill up "Pressure igniters (Flame front Propagation Type)" normally.

The pressure igniters shall be installed maximum 1500 m from the pilot.

4.1.4 Thermocouple per Pilot (Line No. 38)

Fill up "Yes" and have a note "One Piece per Pilot" additionally.

Install temperature alarm to monitor combustion zone temperature.

4.1.5 Wind Shield per Pilot (Line No. 39)

Fill up "Yes" normally to protect the pilot from wind.

4.2Tip Section (Line No. 41)

Fill up "TO BE SUPPLIED BY VENDOR".

4.2.1 Size (Diameter/Length/Thickness) (Line No.42)

Fill up "By Vendor".The criteria for the selection of diameter are tip velocity. If it is smokeless, it shall be lower than Mach no. 0.2. If it is maximum load, it shall be lower than Mach no. 0.5.

4.2.2 Material (Line No. 43)

Fill up the material considering the fluid and operating temperature.

Especially, It is recommended to use 18/8 alloy steel up to 3~5 m from flare tip when acid gas is generated by combustion.

4.2.3 Flame Stabilizer (Line No. 44)


4.2.4 Wind Shield (Line No. 45)


4.2.5 Lifting Lug (Line No. 46)


4.3Gas Seal Section (Line No. 48)

Fill up "To be supplied by Vendor"

4.3.1 Type (Line No. 49)

The types of gas seal are mainly divided into baffle type and labyrinth type.

The type of gas seal is called as the product's name as the below table.

Normally baffle type seal is cheaper. The cost of support is lower because the weight is light.JOHN ZINKNATIONAL AIROIL BURNER CO.FLAREGAS CORPORATION

BAFFLE TYPEARRESTER SEALFLUIDIC SEALIG SERIES SEAL

LABYRINTH TYPEMOLECULAR SEALFX SERIES SEAL

4.3.2 Size (Diameter./Length/Thickness) (Line No. 50)

Fill up "By Vendor".

4.3.3 Pressure Drop (Line No. 51)

Fill up "By Vendor". The vendor will consider allowable pressure drop shown on Line no. 16.


Fill up the material considering the fluid and operating temperature.

4.4Riser Section (Line No. 5)

To supplied by vendor

4.4.1 Size (Diameter/Length/Thickness) (Line No. 6)

Fill up "By Vendor"


Fill up the material considering fluid and operating temperature.

It is recommended to use 18/8 alloy steel up to 3~5 m from flare tip when acid gas is generated by combustion.

4.5Water Seal Drum (Line No. 9)

Water seal drum is used for back up system of gas seal.

The purge gas is used for backup basically. So, Water seal drum is not mandatory to the entire flare stack.It will generate the flammable solution by absorbing flammable gas in seal water when it is installed for continuous flaring. So, it is not installed for continuous flaring.

The installation is decided by client in general.

Water seal drum can be installed at the stack base or separately from stack. This drum can be installed vertically or horizontally. It is decided after studying economical feasibility and analyzing the advantage or disadvantage of each type.

If it is installed separately from stack. It is out of vendor scope normally. It is designed by the related manuals or documents.

4.5.1 Size (Diameter/Length/Thickness) (Line No. 10)

Fill up "By Vendor" if it is installed in stack base.


Check the fluid, especially the property of the solution which absorbed in water.

4.5.3 Steam Heater (Line No. 12)

It may be required to protect the water freezing by the climate condition.

4.6Knockout Drum (Line No. 13)

Knockout drum separates entrained liquid from flare gas and holds this liquid.

Drum is horizontal or vertical type and can be installed at stack base or separately from stack.

The type is decided by economical feasibility and horizontal type is advantageous when the vapor flow is high or large liquid surge volume is required.

It is normally installed separately from stack and is out of vendor scope.

4.6.1 Size, Pressure Drop, Material (Line No. 14~15)

Fill up "By Vendor" if it is decided to supply by vendor. Design with the related manual or document if it is not vendor scope.Watch out the design temperature for the material selection. C.S can't be used when design temperature is higher than 343.3C or lower than -28.9C.

4.7Air-Craft Warning Lights (Line No. 18)

It shall be installed for above 60 M height according to Korea domestic regulation.

4.8 Local Control Panel (Line No. 19)

Installed in general.Consider the location of LCP carefully. It shall be installed considering heat intensity: Max. Heat Intensity (1500 BTU/FT2-HR)

4.9Platform, Ladder & Handrail (Line No. 20)

By mechanical.

4.10Davit (Line No. 21)

Decided by mechanical.

5CONTROL

5.1Burner Ignition (Line No. 28~30)

Ignition of pilot gas is done in local panel and pilot burner can be re-ignited automatically by flame failure alarms in general.

That is to say, if it is not a special case, select "Automatic Re-Ignition".

6CODE & STANDARD (LINE NO.33~36)

Flare stack height is influenced by emissivity value; Vendor standard is more economical than API unless there is any special requirement in Job Specification.Follow BEDD for other requirement.

7CONSTRUCTION7.1Overall Stack Height (Line No. 39)

By vendorIn stage of TBE, emissivity value calculated by vendor in quotation is checked, proper stack height is decided with client and quotation is requested to re-issue with final height.

The stack height is affected by limitation of radiation and environmental limitation of contaminant.

7.2Support Method (Line No. 40)

Cost comparison (Guyed Flare, Self Support Flare

Documents

SEM-9500E Flare Stack