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IPS-E-PR-745(1)
This Standard is the property of Iranian Ministry of Petroleum. All rights are reserved to the owner. Neither whole nor any part of this document may be disclosed to any third party, reproduced, stored in any retrieval system or transmitted in any form or by any means without the prior written consent of the Iranian Ministry of Petroleum.
ENGINEERING STANDARD
FOR
PROCESS DESIGN OF VACUUM EQUIPMENT
(VACUUM PUMPS AND STEAM JET - EJECTORS)
FIRST EDITION
OCTOBER 2014
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IPS-E-PR-745(1)
FOREWORD
The Iranian Petroleum Standards (IPS) reflect the views of the Iranian Ministry of Petroleum and are intended for use in the oil and gas production facilities, oil refineries, chemical and petrochemical plants, gas handling and processing installations and other such facilities.
IPS is based on internationally acceptable standards and includes selections from the items stipulated in the referenced standards. They are also supplemented by additional requirements and/or modifications based on the experience acquired by the Iranian Petroleum Industry and the local market availability. The options which are not specified in the text of the standards are itemized in data sheet/s, so that, the user can select his appropriate preferences therein
The IPS standards are therefore expected to be sufficiently flexible so that the users can adapt these standards to their requirements. However, they may not cover every requirement of each project. For such cases, an addendum to IPS Standard shall be prepared by the user which elaborates the particular requirements of the user. This addendum together with the relevant IPS shall form the job specification for the specific project or work.
The IPS is reviewed and up-dated approximately every five years. Each standards are subject to amendment or withdrawal, if required, thus the latest edition of IPS shall be applicable
The users of IPS are therefore requested to send their views and comments, including any addendum prepared for particular cases to the following address. These comments and recommendations will be reviewed by the relevant technical committee and in case of approval will be incorporated in the next revision of the standard.
Standards and Research department
No.17, Street14, North kheradmand
Karimkhan Avenue, Tehran, Iran.
Postal Code- 1585886851
Tel: 021-88810459-60 & 021-66153055
Fax: 021-88810462
Email: [email protected]
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IPS-E-PR-745(1)
GENERAL DEFINITIONS:
Throughout this Standard the following definitions shall apply.
COMPANY:
Refers to one of the related and/or affiliated companies of the Iranian Ministry of Petroleum such as National Iranian Oil Company, National Iranian Gas Company, National Petrochemical Company and National Iranian Oil Refinery And Distribution Company.
PURCHASER:
Means the “Company” where this standard is a part of direct purchaser order by the “Company”, and the “Contractor” where this Standard is a part of contract documents.
VENDOR AND SUPPLIER:
Refers to firm or person who will supply and/or fabricate the equipment or material.
CONTRACTOR:
Refers to the persons, firm or company whose tender has been accepted by the company.
EXECUTOR:
Executor is the party which carries out all or part of construction and/or commissioning for the project.
INSPECTOR:
The Inspector referred to in this Standard is a person/persons or a body appointed in writing by the company for the inspection of fabrication and installation work.
SHALL:
Is used where a provision is mandatory.
SHOULD:
Is used where a provision is advisory only.
WILL:
Is normally used in connection with the action by the “Company” rather than by a contractor, supplier or vendor.
MAY:
Is used where a provision is completely discretionary.
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CONTENTS: PAGE No.
1. SCOPE ................................................................................................................................... 2 2. REFERENCES ................................................................................................................................ 2 3. SYMBOLS AND ABBREVIATIONS ............................................................................................... 2 4. UNITS ................................................................................................................................... 3 5. GENERAL ................................................................................................................................... 3
5.1 Definition of Vacuum Pumps and Related Terms ................................................................ 3 5.2 Definition of Steam Jet Ejector and Related Term ............................................................ 11 5.3 Vacuum Equipment Classification ...................................................................................... 16 5.4 Type Selection Considerations ........................................................................................... 16
6. DESIGN CRITERIA ....................................................................................................................... 20 6.1 Common Basic Calculation ................................................................................................. 20 6.2 Design Considerations for Ejectors .................................................................................... 23
7. VACUUM SAFETY ........................................................................................................................ 28 APPENDICES: APPENDIX A ................................................................................................................................. 29 APPENDIX B TYPICAL PIPING AND INSTRUMENT DIAGRAMS (P & IDS) AROUND VACUUM
SYSTEMS ................................................................................................................. 31 APPENDIX C ESTIMATION OF POWER CONSUMPTION FOR VACUUM PUMPS ................... 33 APPENDIX D STANDARD EJECTOR UNITS DESIGNATIONS CONFORMING TO HEAT
EXCHANGE INSTITUTE .......................................................................................... 34 APPENDIX E TYPICAL EJECTOR DATA SHEET ........................................................................ 36
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0. INTRODUCTION
"Pressure Reducing/Increasing Machineries and/or Equipment" are broad and contain variable subjects of paramount importance. Therefore, a group of process engineering standards are prepared to cover the subject.
This group includes the following standards:
STANDARD CODE STANDARD TITLE
IPS-E-PR-745 "Engineering Standard for Process Design of Vacuum Equipment (Vacuum Pumps and Steam Jet Ejectors)"
IPS-E-PR-750 "Engineering Standard for Process Design of Compressors"
IPS-E-PR-755 "Engineering Standard for Process Design of Fans and Blowers"
This Standard covers:
VACUUM EQUIPMENT
(VACUUM PUMPS AND STEAM JET EJECTORS)
This Standard covers the process aspects of engineering calculations for vacuum systems and the relevant equipment.
Since the working mechanism of certain types of vacuum pumps such as positive displacement types are the same as gas compressors, these types are not discussed in detail in this standard and therefore the "Design Criteria" section mainly discusses about the "Ejectors", which are the most frequently used vacuum devices in Oil, Gas and Petrochemical processes.
In this standard, some of the subjects are adapted from the following specifications and handbooks: − “Applied Process Design”, vol.1, 3th Edition, by Ernest Ludwig. − Design Practice by ExxonMobil Engineering, “section XI-J (Ejectors)”, 2001 − “Process Plants Division, by Foster Wheeler”, Process STD 704 (Steam Jets & Ejectors),
Rev.10, 2002. − “Standard Practice, by JGC”, STD-09-040 (Section3, Ejectors) Rev.0, 2003.
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1. SCOPE This standard is intended to cover requirements for process design, selection of proper type of vacuum equipment and process calculation including estimation for number of stages, air leakage and rough estimation of utility consumption. Note 1: This standard specification is reviewed and updated by the relevant technical committee on Aug. 1998. The approved modifications by T.C. were sent to IPS users as amendment No. 1 by circular No. 30 on Aug. 1998. These modifications are included in the present issue of IPS.
Note 2:
This is a revised version of this standard, which is issued as revision (1)-2014. Revision (0)-1993 of the said standard specification is withdrawn. 2. REFERENCES
Throughout this Standard the following dated and undated standards/codes are referred to. These referenced documents shall, to the extent specified herein, form a part of this standard. For dated references, the edition cited applies. The applicability of changes in dated references that occur after the cited date shall be mutually agreed upon by the Company and the Vendor. For undated references, the latest edition of the referenced documents (including any supplements and amendments) applies.
IPS (IRANIAN PETROLEUM STANDARDS)
IPS-E-GN-100 "Engineering Standard for Units" IPS-M-ME-256 "Material and Equipment Standard for Steam Jet Ejectors" IPS-E-PR-250 "Engineering Standard for Performance Guarantee" IPS-E-PR-750 "Engineering Standard for Process Design of Compressors"
HEAT EXCHANGE INSTITUTE Inc.
"Standard for Steam Jet Ejectors", 3rd. Ed. 1980 "General Construction Standard for Ejector Componenets other than Ejector Condensers", 1st. Ed.
ISO (INTERNATIONAL ORGANIZATION FOR STANDARDIZATION)
3529/2 "Vacuum Technology-Vocabulary" Part 2: "Vacuum Pumps and Related Terms"
1st. Ed. 1981 3. SYMBOLS AND ABBREVIATIONS
A = Quotational Price. B = Steam Cost Per Ton. C = Cooling Water Cost Per 1000 m3. F = Capital Charge Percentage. g = Acceleration of Gravity = 9.806 m/s2. Gs = Steam Consumption, Tons Per Year in (t/a). Gw = Cooling Water Consumption, in (1000 m3/a). H = Height, in (meters).
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Mn = Molecular Mass of Noncondensable Gas, in (kg/kmol). Mv = Molecular Mass of Condensable Vapor, in (kg/kmol). P1 = Initial Pressure in System, in [mm Hg (abs.)]. P2 = Final Pressure in System, in [mm Hg (abs.)]. Pc = Condensate Pressure in Condenser, in (kPa). Pn = Partial Pressure of Non-Condensable Gas, in [mm Hg (abs.)]. Po = Barometric Pressure at Liquid Level, in (kPa). Pv = Partial Pressure of Condensable Vapor, in [mm Hg (abs.)]. Q = Throughput of a Vacuum Pump, in (Pa. m3/s). S = Volume Flow Rate of a Vacuum Pump, in (m3/s). T = Absolute Temperature, in (K). V = Volume, in (m3). W = Capacity of Ejector, in (kg/h). Wn = Mass Flow Rate of Non-Condensable Gas, in (kg/h). Wv = Mass Flow Rate of Condensable Vapor, in (kg/h). Δp = Pressure Difference due to Friction Losses, in (kPa). ρL = Mass Density of Liquid, in (kg/m3).
4. UNITS This standard is based on international system of units (SI), as per IPS-E-GN-100 except where otherwise specified. 5. GENERAL Vacuum equipment, as called by ISO (International Organization for Standardization),"Vacuum Pumps", are defined as devices for creating, improving and/or maintaining a vacuum. In OGP industries the name "Vacuum Pump" is conventionally used for rotating machine vacuum devices. Vacuum equipment are divided into two main groups, Vacuum Pumps and Ejectors. 5.1 Definition of Vacuum Pumps and Related Terms Definitions of vacuum pumps and related terms of ISO-3529/2, as the following paragraphs are generally accepted in this Standard.
5.1.1 Vacuum pumps
5.1.1.1 Vacuum pump
A device for creating, improving and/or maintaining vacuum. Two basically distinct categories may be considered: gas transfer pumps (2.1.1 and 2.1.2) and entrapment or capture pumps (2.1.3).
5.1.1.2 Positive displacement (vacuum) pump
A vacuum pump in which a volume filled with gas is cyclically isolated from the inlet, the gas being then transferred to an outlet. In most types of positive displacement pumps the gas is compressed before the discharge at the outlet. Two categories can be considered: reciprocating positive displacement pumps (2.1.1.1) and rotary positive displacement pumps (2.1.1.2 to 2.1.1.4).
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5.1.1.2.1 Terms relating to positive displacement pumps
5.1.1.2.1.1 Gas ballast (vacuum) pump
A positive displacement pump in which a controlled quantity of a suitable non-condensable gas is admitted during the compression part of the cycle so as to reduce the extent of condensation within the pump. This devise may be incorporated in any types of pumps in 2.1.1.3.1 to 2.1.1.3.3.
5.1.1.2.1.2 Oil-sealed [liquid-sealed] vacuum pump
A rotary positive displacement pump in which oil is used to seal the gap between parts which move with respect to one another and to reduce the residual free volume in the pump chamber at the end of the compression part of the cycle.
5.1.1.2.1.3 Dry-sealed vacuum pump
A positive displacement pump which is not oil-sealed (liquid-sealed).
5.1.1.2.2 Piston vacuum pump
A positive displacement pump in which the gas is compressed and expelled due to the movement of a reciprocating piston moving in a cylinder.
5.1.1.2.3 Liquid ring vacuum pump
A positive displacement pump in which an eccentric rotor with fixed blades throws a liquid against the stator wall. The liquid takes the form of a ring concentric to the stator and combines with the rotor blades to define a varying volume.
5.1.1.2.4 Rotary pumps using sliding separators
5.1.1.2.4.1 Sliding vane rotary vacuum pump
A positive displacement pump in which an eccentrically placed rotor is turning tangentially to the fixed surface of the stator. Two or more vanes sliding in slots of the rotor (usually radial) and rubbing on the internal wall of the stator, divide the stator chamber into several parts of varying volume.
5.1.1.2.4.2 Rotary piston vacuum pump
A rotary displacement pump in which a rotor is turning eccentrically, in contact with the internal wall of the stator. A device moving relative to the stator is pressed against the rotor and divides the stator chamber into parts of varying volume.
5.1.1.2.4.3 Rotary plunger vacuum pump
A rotary displacement pump in which a rotor is turning eccentrically to the internal wall of the stator. The stator chamber is divided into two parts of varying volume by a vane rigidily fixed to the rotor. The vane slides in a plug oscillating in an appropriate housing in the stator.
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5.1.1.2.5 Roots vacuum pump
A positive displacement pump in which two lobed rotors. Interlocked and synchronized, rotate in opposite directions moving past each other and the housing wall with a small clearance and without touching.
5.1.1.2.6 Trochoid pump
A rotary positive displacement in which the cross-section of the rotor has trochoidal shape (for example an ellipse) whose centre of gravity describes a circle.
5.1.1.3 Kinetic vacuum pump
A vacuum pump in which a momentum is imparted to the gas or the molecules in such a way that the gas is transferred continuously from the inlet to the outlet. Two categories can be considered: Fluid entrainment pumps and drag vacuum pumps.
5.1.1.3.1 Turbine vacuum pump
A rotary kinetic pump in which the transfer of a large amount of gas is obtained by a rapidly rotating device. The dynamic sealing is obtained without rubbing. The gas flow either may be directed parallel to the axis of rotation (axial flow pump) or at right angles to the axis of rotation (radial flow pump).
5.1.1.3.2 Ejector vacuum pump
A kinetic pump which uses the pressure decrease due to Venturi effect and in which the gas is entrained in a high-speed stream towards the outlet. An ejector pump operates when viscous and intermediate flow conditions obtain.
5.1.1.3.2.1 Liquid jet vacuum pump
An ejector pump in which the entrainment fluid is a liquid (usually water).
5.1.1.3.2.2 Gas jet vacuum pump
An ejector pump in which the entrainment fluid is a non-condensable gas.
5.1.1.3.2.3 Vapour jet vacuum pump
An ejector pump in which the entrainment fluid is a vapour (water, mercury or oil vapour).
5.1.1.3.3 Diffusion pump
A kinetic pump in which a low-pressure, high-speed vapour stream provides the entrainment fluid. The gas molecules diffuse into this stream and are driven to the outlet. The number density of gas molecules is always low in the stream. A diffusion pump operates when molecular flow conditions obtain.
5.1.1.3.3.1 Self-purifying diffusion pump
An oil vapour diffusion pump in which the volatile impurities of the operating fluid are prevented from returning to the boiler but are transported towards the outlet by a special design.
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5.1.1.3.3.2 Fractionating diffusion pump
A multi-stage oil vapour diffusion pump in which the lowest pressure stage is supplied with the more dense, low vapour pressure constituents of the operating fluid, and where the higher pressure stages are supplied with the less dense constituents of higher vapour pressure.
5.1.1.3.4 Diffusion-ejector pump
A multi-stage kinetic pump in which a stage or stages having the characteristics of an ejector pump.
5.1.1.3.5 Molecular drag pump
A kinetic pump in which a momentum is imparted to the gas molecules by contact between them and the surface of a high-speed rotor, causing them to move towards the outlet of the pump.
5.1.1.3.5.1 Turbo-molecular pump
A molecular drag pump in which the rotor is fitted with discs provided with slots or blades rotating between corresponding discs in the stator. The linear velocity of a peripheral point of the rotor is of the same order of magnitude as the velocity of the gas molecules. A turbo-molecular pump operates normally when molecular flow conditions obtain.
5.1.1.3.6 Ion transfer pump
A kinetic pump in which the gas molecules are ionized and then transferred towards an outlet by means of electric fields combined or not with a magnetic field.
5.1.1.4 Entrapment [capture] vacuum pump
A vacuum pump in which the molecules are retained by sorption or condensation on internal surfaces.
5.1.1.4.1 Adsorption pump
An entrapment pump in which the gas is retained mainly by physical adsorption of a material of large area {for example a porous substance}.
5.1.1.4.2 Getter pump
An entrapment pump in which the gas is retained principally by chemical combination with a “getter”. This is usually a metal or a metal alloy, either in bulk or in the form of a freshly deposited thin film.
5.1.1.4.3 Sublimation [evaporation] pump
An entrapment pump in which a getter material is sublimed [evaporated].
Note: In that context evaporation and sublimation are similar concepts.
5.1.1.4.4.1 Sublimation {evaporation} ion pump
A getter ion pump in which the ionized gas is transferred towards a getter which is produced by sublimation or evaporation in either a continuous or discontinuous way.
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5.1.1.4.4.2 Sputter ion pump
A getter ion pump in which the ionized gas is transferred toward
5.1.1.4.5 Cryopump
An entrapment pump consisting of surfaces refrigerated to low temperature sufficient to condense residual gases. The condensate is then maintained at a temperature such that the equilibrium vapour pressure is equal to or less than the desired low pressure in the chamber.
Note: The temperature chosen shall be in the range below 120 K depending on the nature of the gases to be pumped.
5.1.2 Parts of Pump
5.1.2.1.1 Pump case
The external wall of a pump, which separates the low pressure gas from the atmosphere.
5.1.2.1.2 Inlet
The port by which gas to be pumped enters a pump.
5.1.2.1.3 Outlet
The outlet or discharge port of a pump.
5.1.2.2.1 Vane; blade
A sliding member which divides into compartments the working space between the rotor and stator in some positive displacement rotary pumps.
5.1.2.2.2 Discharge valve
A valve operating automatically for the discharge of gas from the compression chamber of some positive displacement pumps, into which the pumped gas is expanded.
5.1.2.2.3 Expansion chamber
The increasing space within the stator chamber of some positive displacement pumps, into which the pumped gas is expanded.
5.1.2.2.4 Compression chamber
The decreasing space within the stator chamber of some positive displacement pumps, into which the gas is compressed before being discharged.
5.1.2.2.5 Vacuum pump oil
Liquid used for sealing, cooling and lubrication, in oil-sealed vacuum pumps.
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Note: The term pump oil is also commonly used to describe pump fluids used in oil vapour pumps. This note does not apply to the German expression.
5.1.2.3.1 Pump fluid
The operating fluid of an ejector or diffusion pump.
5.1.2.3.2 Nozzle
The part of an ejector or diffusion pump used to direct flow of the pump fluid order to produce the pumping action.
5.1.2.3.2.1 Nozzle throat
Smallest cross-section of the nozzle.
5.1.2.3.2.2 Nozzle clearance area
The smallest cross-sectional area between the outer rim of a nozzle and the wall of the pump casing.
5.1.2.3.2.3 Nozzle clearance
The width of the annuals determining the nozzle clearance area.
5.1.2.3.3 Jet
The stream of pump fluid issuing from a nozzle, in an ejector or diffusion pump.
5.1.2.3.4 Diffuser
The converging section of the wall of an ejector pump.
5.1.2.3.4.1 Diffuser throat
The part of a diffuser having the smallest cross-sectional area.
5.1.2.3.5 Vapour tube; vapour pipe; vapour chimney
The tube through which the vapour passes from the boiler to the nozzle or nozzles of a vapour jet or diffusion pump.
5.1.2.3.6 Nozzle assembly
The integral system of nozzles and vapour ducts (usually removable) in a vapour jet or diffusion pump.
5.1.2.3.7 Skirt
The lower part of the nozzle assembly, usually enlarged, separating the returning condensed pump fluid and the vapour generated by the pump boiler.
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5.1.3 Accessories
5.1.3.1 Trap
A device in which the partial pressure of the constituents of a mixture of gases and vapours is reduced by physical or chemical means.
5.1.3.1.1 Cold trap
A trap which operates by condensation on cooled surfaces.
5.1.3.1.2 Sorption trap
A trap which operates by sorption.
5.1.3.1.3 Ion trap
A trap in which ionization processes are employed to remove cetain undesirable constituents from the gas phase.
5.1.3.2 Baffle
A system of screens, possibly cooled, placed near the inlet of a vapour jet or diffusion pump, to reduce back-streaming and back-migration.
5.1.3.3 Oil separator
A device which reduces the loss of pump oil by entrainment as droplets at the outlet of a vacuum pump.
5.1.3.4 Oil purifier
A device for removing contaminants from the pump oil.
5.1.4 Categories of pumps with reference to operation
5.1.4.1 Rough [low] vacuum pump
A vacuum pump for reducing the pressure in a vessel, from atmospheric.
5.1.4.2 Roughing vacuum pump
A vacuum pump for reducing the pressure in a vessel or system from atmospheric to a value at which another pumping system can begin to operate.
5.1.4.3 Backing vacuum pump
A vacuum pump for maintaining the backing pressure of another pump below its critical value. A backing pump may be used as a roughing pump.
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5.1.4.4 Holding vacuum pump
An auxiliary pump for maintaining the backing pressure or certain types of vacuum pump when the low gas flow rate at that time does not warrant the use of the main backing pump.
5.1.4.5 High vacuum pump
When the pumping system is composed of more than one pump in series, it is the pump which operates in the lowest pressure range.
5.1.4.6 Booster vacuum pump
A vacuum pump generally used between the backing pump and the high vacuum pump either to increase the throughput of the pumping system in a medium range of pressure, or to improve the pressure stages within the system and so reduce the volume flow rate needed for the backing pump.
5.1.4.7 Appendage vacuum pump
A small auxiliary vacuum pump used to maintain a low pressure in a vessel already evacuated.
5.1.5 Characteristics of Pumps
5.1.5.1.1 Volume flow rate of a vacuum pump
[symbol: S; unit: m3.s-1]: It is the volume flow rate of the gas phase within the evacuated chamber. This kind of definition is only applicable to pumps which are distinct devices, separated from the vacuum chamber. For practical purposes, however, the volume flow rate of a given pump for a given gas is, by conversation, taken to be the throughput of that gas flowing from a standardized test dome connected to the pump, divided by the equilibrium pressure measured at a specified position in the test dome, and under specified conditions of operation.
5.1.5.1.2 Throughput of vacuum pump
[symbol: Q; unit: Pa.m3.s-1]: The throughput flowing through the inlet of the pump.
5.1.5.2 Starting pressure
Pressure at which a pump can be started without damage and a pumping effect can be obtained.
5.1.5.3.1 Backing pressure
The pressure at the outlet of a pump which discharges gas to a pressure below atmospheric.
5.1.5.3.2 Critical backing pressure
The backing pressure above which a vapour jet or diffusion pump fails to operate correctly. It is the highest value of the backing pressure at which a small increment in the backing pressure does not yet produce a significant increase of the inlet pressure. The critical backing pressure of a given pump depends mainly on the throughput.
Note: For some pumps the failure does not occur abruptly and the critical backing pressure cannot then be precisely stated.
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5.1.5.3.3 Maximum backing pressure
The backing pressure above which a pump can be damaged.
5.1.5.4 Maximum working pressure
The inlet pressure corresponding to the maximum gas flow rate the pump is able to withstand under continuous operation without any deterioration or damage.
5.1.5.5 Ultimate pressure of a pump
The value towards which the pressure in a standardized test dome tends asymptotically, without introduction of gas and with the pump operating normally. A distinction may be made between the ultimate pressure due only to non-condensable gases and the total ultimate pressure due to gases and vapours.
5.1.5.6 Compression ratio
The ratio of the outlet pressure to the inlet pressure, for a given gas.
5.1.5.7.1 Back-diffusion of gas
The passage of gas, opposite to the pumping action, from the outlet to the inlet port of a vacuum pump (or of any associated baffle or trap).
5.1.5.7.2 Back-streaming of pump fluid
The passage of the pump fluid through the inlet port of the fluid entrainment pump {or of any associated baffle or trap} in a direction opposite to the direction of desired gas flow.
5.2 Definition of Steam Jet Ejector and Related Term
The definitions of steam jet ejectors and related terms used in the following paragraphs are mostly obtained from HEI and LUDWIG.
5.2.1 Steam ejector
An ejector is a type of vacuum pump or compressor. Since an ejector has no valves, rotors, pistons or other moving parts, it is a relatively low-cost component is easy to operate and requires relatively little maintenance. In a steam-jet ejector, the suction chamber is connected to the vessel or pipeline that is to be evacuated under vacuum. The gas that is to be induced into the suction chamber can be any fluid that is compatible with the steam and the components’ materials of construction.
5.2.2 Ejectors may, in one sense, be put into two categories: condensing and non-condensing. The condensing type utilizes condensers between ejector stages to remove condensable vapor and, therefore, require a source of cooling water. The non-condensing ejector has its stages connected directly together, with succeeding stages handling the motive steam from preceding stages. This type requires no cooling water. However, it uses considerably more steam than the condensing type to handle a given load.
5.2.3 Steam ejector parts, nomenclature
With the view of establishing standard terminology, the four sketches in Fig. 1 are shown of basic steam jet ejector stage assembly. It should be noted, however, that these sketches are merely illustrative for the purpose of indicating names of parts. (see 2., HEI).
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TYPICAL STEAM JET EJECTOR STAGE ASSEMBLIES
Fig. 1
1. Diffuser 7. Suction
2. Suction Chamber 8. Discharge
3. Steam Nozzle 9. Steam Inlet
4. Nozzle Extensions (if used) 10. Nozzle Throat
5. Steam Chest 11. Diffuser Throat
6. Nozzle Plate (if used)
5.2.4 Characteristic terms
Definition of terms used in this part of the Standard are given in the following paragraphs (see 2.1, Ludwig and HEI).
a) Absolute Pressure
Is the pressure measured from absolute zero; i.e., from an absolute vacuum.
b) Static Pressure Is the pressure measured in the gas in such manner that no effect on the measurement is produced by the velocity.
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c) Suction Pressure Is the absolute static pressure prevailing at the suction of the ejector expressed in millimeters or micrometers (microns) of mercury. d) Discharge Pressure Is the absolute static pressure prevailing at the discharge of the ejector expressed in millimeters of mercury. e) Breaking Pressure Is that pressure of either the motive steam or the discharge, which causes the ejector to become unstable. f) Recovery Pressure (Pick up Pressure) Is that pressure of either the motive steam or the discharge, at which the ejector recovers to a condition of stable operation. g) Absolute Temperature Is the temperature above absolute zero. It is shown by the symbol (T) and Expressed in degrees kelvin (K), which is equal to degrees Celsius (°C) plus 273.15. h) Suction Temperature Is the temperature of the gas at the suction of the ejector. i) Stable Operation Is the operation of the ejector without violent fluctuation of the suction pressure. j) Capacity Is the mass rate of flow of the gas to be handled by the ejector. Capacity is shown by the symbol (W) and the unit is kilograms per hour (kg/h). k) Dry Air Atmospheric air at normal room temperature is considered dry air. The very small mass of water in it is considered insignificant and is ignored. For example, the mass of water vapor in atmospheric air at 50 percent relative humidity and 27°C is less than 0.011 kg per kg of air. l) Equivalent Air Is a calculated mass rate of air that is equivalent to the mass rate of gas handled by the ejector at the suction conditions. The unit is kilograms per hour. m) Equivalent Steam Is a calculated mass rate of steam that is equivalent to the mass rate of gas handled by the ejector at the suction conditions. The unit is kilograms per hour. n) Molecular Mass Is the sum of the atomic masses of all the atoms in a molecule. o) Mol Mol is a mass numerically equal to the molecular mass.
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p) Mol Fraction Mol fraction of a component in a homogeneous mixture is defined as the number of mols of that component divided by the sum of the number of mols of all components. q) Total Steam Consumption Is the total mass rate of flow passing through nozzles of all ejector stages at specified conditions of steam pressure and temperature. The unit is kilograms per hour. r) Total Water Consumption Is the total rate of flow passing through the ejector condensers at specified inlet temperature. The unit is cubic meters per hour (m3/h). s) Critical Flow Is the flow through a nozzle when the downstream absolute pressure is below critical pressure, i.e., the downstream absolute pressure must be less than 50 percent of the upstream absolute pressure. t) Subcritical Flow Is the flow through a nozzle when the downstream absolute pressure is above critical pressure, i.e., there is a relatively low pressure drop across the nozzle. u) Temperature Entrainment Ratio Is the ratio of the mass of air or steam at 21°C temperature to the mass of air or steam at a higher temperature that would be handled by the same ejector operating under the exact same conditions. v) Molecular Mass Entrainment Ratio Is the ratio of the mass of gas handled to the mass of air which would be handled by the same ejector under the exact same conditions.
5.2.5 Operating Principles Operating principles of a steam jet ejector and capabilities and limitations of ejector systems may be found in different textbooks and standards. HEI standard (see 2.) is recommended for such purpose. 5.2.6 Ejector unit types Some of the various types of ejector units commonly used are illustrated in Fig 2(a) to (h). This figure is taken from HEI standard. For detail explanation of each unit type, reference is made to Fig. 9 and paragraph E5 to E13 of this standard (see 2.1).
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COMMON TYPE OF EJECTOR UNITS
Fig. 2
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5.3 Vacuum Equipment Classification ISO classification of vacuum equipment (vacuum pumps) is shown in Fig. 3, (see 2.). 5.4 Type Selection Considerations Vacuum equipment can be roughly divided into "Ejectors" and "Vacuum Pumps", as mentioned in previous sections. Three major factors should be considered in the type selection stage for vacuum devices. These factors are operating requirements (i.e., suction pressure), suction gas properties and cost. As a general procedure for type selection, the flow chart shown in Fig. 4 can be used. 5.4.1 Operating conditions Application range of different type of vacuum equipment can be found in Fig. 5. In selecting the type of vacuum pump, the characteristics of the individual types and the process conditions involved must be fully considered. Contact with the vendors is also necessary. The characteristics of vacuum pumps and ejector are given in Table. 1. For ejector, once the operating pressure is determined, the number of stages can be determined from Fig. 5. 5.4.2 Comparison of costs Generally, steam ejectors require less initial cost and have no moving parts, and hence they have high reliability. On the other hand, their disadvantage is that their utility cost is high. Meanwhile, in the case of vacuum pumps, although they cost 5 to 20 times as much as steam ejectors and require high maintenance cost, their utility cost is lower. Regarding the operating costs, a general measure will be that, where the suction gas volume is large and the operating pressure is high, vacuum pumps will require less operating cost than steam ejectors. 5.4.3 Properties of suction gas
a) In the case of steam ejectors which produce a large quantity of waste liquid, their use will be disadvantageous unless the cost of the waste liquid treatment is cheap. b) Where corrosive gases must be handled, steam ejectors, which can be manufactured of almost any material, will be advantageous.
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SELECTION STEPS OF VACUUM EQUIPMENT
Fig. 3
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Notes:
1) Ejectors have no moving parts.
2) A large amount of pressurized air needed. Cost and space saving, but large relieving noise.
3) Atmospheric air used.
4) Rotary pump works in wide pressure range.
5) Atmospheric leg (10 m) and waste water treatment needed.
6) Motive water is used. Water consumption rte is high.
7) Not good for the case when a lot of inert gas exists.
SELECTION STEPS OF VACUUM EQUIPMENT
Fig. 4
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APPLICATION RANGE OF VACUUM EQUIPMENT
Fig. 5
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TABLE 1 - CHARACTERISTICS OF VACUUM EQUIPMENT
O: Possible
Δ: With proper maintenance
Χ: Impossible
6. DESIGN CRITERIA
The basic design stage of vacuum pumps and ejectors, can be divided into two distinct parts, first is the calculation of parameters or factors which are common for all vacuum devices, such as those concerning the suction conditions. On the other hand, there are some calculations which regards specifically on; and differs for; each equipment type. In the following sections, each part is individually discussed, except that since vacuum pumps are considered principally as compressors, no special basic calculation method for this type is presented here and methods presented in IPS-E-PR-750, "Process Design of Compressors", shall be used for this purpose.
Typical P&I diagrams for vacuum pump and ejector vacuum systems are shown in Appendix B.
6.1 Common Basic Calculation
The following procedure should be followed for calculating the suction parameters required to fix a vacuum system and to design the equipment basically.
a) Determine vacuum required at the critical process point in the system.
b) Calculate pressure drop from this point to the process location of the suction flange of the first stage vacuum equipment.
c) At the vacuum device suction condition determine:
I) Kilogram per hour of condensable vapor.
II) Kilogram per hour of non-condensable gases which are:
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- dissolved
- injected or carried in the process
- formed by reaction
- air leakage
6.1.1 Suction pressure
The suction pressure of a vacuum device is expressed in absolute units. If it is given as millimeters of vacuum it must be converted to absolute units by using the local or reference barometer.
In actual operation suction pressure follows the ejector capacity curve, varying with the non-condensable and vapor load to the unit.
6.1.2 Discharge pressure
As indicated, performance of a vacuum unit is a function of backpressure. In order to insure proper performance, the atmospheric discharge units shall be designed for a back pressure of 6 kPa (ga.) unless otherwise specified. The pressure drop through any discharge piping and aftercooler must be taken into consideration. Discharge piping should not have pockets for condensation.
6.1.3 Capacity of the unit
The capacity of a vacuum unit is expressed as kilograms per hour total of non-condensable plus condensables to the inlet flange of the unit. For multistage ejector units, the total capacity must be separated into kilograms per hour of condensables and noncondensables. The final stages are only required to handle the non condensable portion of the load plus the saturation moisture leaving the intercondensers.
An example of actual capacity calculation for process vapor plus noncondensables can be found in Appendix A.
6.1.3.1 Few vacuum systems are completely airtight, although some may have extremely low leakage rates. Considering the air and non-condensable:
(kg/h air + non-condensable)= air-in leakage + process released air + process released non-condensable
See Fig.6, recommended by "ExxonMobil Research and Engineering Company", which has been used conventionally for estimation of air leakage.
6.1.3.2 Dissolved gases released from water When vacuum units pull non-condensable and other vapors from a direct contact condenser (barometric, low level jet, deaerator) there is also a release of dissolved gases, usually air, from water. This air must be added to the other known load of the unit. Fig. 7 presents the data of the "Heat Exchange Institute" for the amount of air that can be expected to be released when cooling water is sprayed or otherwise injected into open type barometric or similar equipment.
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SYSTEM VOLUMES (m3) AIR LEAKAGE VALUES
Fig. 6
AIR RELEASED FROM WATER kg air /1000 m3/h WATER
DISSOLVED AIR RELEASED FROM WATER ON DIRECT CONTACT IN VACUUM SYSTEMS
Fig. 7
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6.1.4 Utility requirements
Although utility consumption is usually determined by vendors, as a rough estimation, methods presented in 6.2.2.3 (for ejectors) and Appendix C, (for vacuum pumps) can be used.
6.2 Design Considerations for Ejectors
6.2.1 General
6.2.1.1 For construction design considerations and factors such as design pressure, etc., refer to "HEI, General Construction Standards for Ejector Components other than Ejector Condensers", (see. 2.) and IPS-M-ME-256 (see 2.).
6.2.1.2 The design and construction shall be proven in practice, robust and reliable. Unless otherwise specified, the ejectors shall be designed in accordance with IPS-M-ME-256, "Ejectors".
6.2.1.3 Safety, ease of operation, inspection, maintenance, repair and cleaning are of major concern. Nozzles, nozzle inspection ports and pressure taps shall be readily accessible.
6.2.1.4 Where there is danger from freezing during operation affecting parts that can not be drained, protection against such freezing shall be provided.
6.2.1.5 Provisions shall be made for cases where there is danger of plugging due to the carry over of high viscosity or high melting point liquids.
6.2.1.6 Adequate personnel protection or insulation shall be provided for all surfaces hotter than 60°C.
6.2.1.7 Performance of the ejector shall be guaranteed by the contractor in accordance with IPS-E-PR-250 "Performance Guarantee" (see 2.).
6.2.1.8 Spectacle blind shall be considered between process and vacuum sources (ejector, vacuum pump) for leak test to confirm vacuum performance.
6.2.1.9 Economic criterion
Steam jet vacuum ejectors shall be designed or selected such that an optimum is obtained between capital and operating costs.
For the purpose of the calculation it is, however, sufficient to apply the criterion that:
F.A + (B.Gs+C.Gw) is a minimum.
(For definition of symbols see section 3).
where the range of size of ejector options is such that changes may be required in the supporting structure, the appropriate differential capital costs should be taken up in the calculation.
6.2.2 Design factors and parameters
The following factors should be carefully specified for process design (rating) and selecting an ejector system for vacuum operation.
6.2.2.1 Capacity
The following capacity requirements shall be specified:
a) The absolute pressure to be maintained.
b) The total mass in kilograms per hour of the gas to be entrained.
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c) The temperature of the gas to be entrained.
d) Composition of the gas to be entrained. The mass of each constituent shall be specified in kilograms per hour.
e) If the gas is other than air or water vapor, its physical and chemical properties shall be fully specified.
Note:
When actual performance curves for the temperature and vapor mixture in question is not available, the capacity should be evaluated on an equivalent air basis, using HEI method (see 2.), an example of such evaluation is presented in Appendix A.
6.2.2.2 Utilities
6.2.2.2.1 Steam
The following characteristics of the operating steam shall be specified:
a) Maximum steam line pressure and temperature.
b) Maximum steam pressure and temperature at the ejector steam inlet.
c) Minimum steam pressure at the ejector steam inlet.
d) Design steam pressure and temperature.
e) Quality of the steam, if it is not superheated, at the ejector steam inlet.
To prevent the nozzle throat of the ejector from becoming too small to be practical and to ensure of having stable operation of the unit, the manufacturer may elect to use design steam pressure lower than the available steam pressure at the ejector steam inlet.
It is recommended that the design steam pressure never be higher than 90 percent of the minimum steam pressure at the ejector steam inlet.
This design basis allows for stable operation under minor pressure fluctuations.
The higher the actual motive steam design pressure of an ejector the lower the steam consumption. When this pressure is above 2500 kPa (ga.), the decrease in steam requirements will be negligible.
For ejector discharging to the atmosphere, steam pressures below 415 kPa (ga.) at the ejector are generally uneconomical.
To ensure stable operations the steam pressure must be above a minimum value. This minimum is called the "Motive Steam Pickup Pressure", and is stated by the manufacturer.
Effect of steam pressures on ejector capacity is shown in Fig. 8.
An increase in steam pressure over design will not increase vapor handling capacity for the normal “fixed capacity” type of ejector.
The steam should be dry, to avoid erosion and clogging the nozzle with water droplets, the latter affecting performance and resulting in fluctuating vacuum. To ensure suitable steam quality in supplies with little or no superheat, the use of a steam separator should be considered. The steam supply should be stated as dry and saturated or if superheated the normal and maximum expected pressures and temperatures given.
The motive steam design pressure should be the minimum expected line pressure minus 5 to 10 p.s.i. This design basis allows for stable operation under minor pressure fluctuations.
For ejectors discharging to atmosphere, steam pressures below 60 psig at the ejector are usually uneconomic.
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6.2.2.2.2 Cooling water
The quality, temperature and pressure of the cooling water should be given together with allowable discharge temperature and pressure drop. The water temperature given should be the maximum expected; but the minimum and average temperatures, together with the duration of maximum supply temperatures are included if they are available.
EFFECTS OF EXCESS STEAM PRESSURE ON EJECTOR CAPACITY
Fig. 8
6.2.2.2.3 Division of load over two parallel elements
When any stage of an ejector line-up consists of two parallel elements (ejectors) the following shall apply:
a) The two elements of the stage shall be designed to handle 1/3rd and 2/3rd respectively of the total design load of that stage. This will give better matching of ejector capacity to load, resulting in energy savings.
b) Provision shall be made to individually isolate each ejector on the vapor side in order to prevent recycling of gas through an idle parallel set. Proper arrangements for safety valve or suitable design pressure should be considered.
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6.2.2.2.4 Barometric legs
Barometric legs of sufficient height shall be installed to safeguard against air ingress and to prevent flooding of the condensers during normal operation. It shall also be ensured that the liquid content of the accumulator vessel is sufficient to fill up the barometric legs.
Barometric legs shall be run separately into a vertical header connected to the condensers vessel, see Appendix B. This separation shall be maintained in order to prevent interference with the respective flows, caused by the difference in condensate rundown temperatures. Except when necessary for personnel protection purposes, thermal insulation or steam tracing should not be applied, unless the liquid hydrocarbons have a waxy nature.
6.2.2.2.5 Condensate outlet temperature
The system shall be so designed that the condensate temperature at each condenser outlet shall not exceed the cooling water inlet temperature by a margin greater than 25°C.
6.2.2.3 Estimation of utility requirements
Utility consumption is mainly determined by the vendors. However, steam consumption may be roughly estimated as follows:
6.2.2.3.1 Where the suction gas is rich in non-condensable gases, the steam consumption may be estimated from Fig. 9 by converting the suction gas volume to its equivalent air volume.
6.2.2.3.2 Where a large quantity of condensed vapor is present in the suction gas, steam consumption may be calculated by estimating the pressure and the suction gas volume at the individual stages of an ejector.
Notes:
1) Where evacuating time become a bottle-neck in designing, the evacuating time may be made longer or start-up equipment may be separately installed to reduce utility consumption. Usually 0.5 up to 1.0 hour may be spent for evacuating during start up.
2) Where reduced operation is conceivable in systems where a large quantity of non-condensable gases is produced, parallel installation of vacuum devices should also be considered.
6.2.2.4 Ejector selection procedure
The following is a suggested procedure for rating and selecting an ejector system for vacuum operation:
1) Follow the steps mentioned in 6.1.
2) Select the number of stages from Table 2 and Fig. 5 or Appendix D.
3) Estimate the steam consumption (see 6.2.2.3).
4) Prepare "Process Specification Sheet", to be forwarded to manufacturers.
TABLE 2- NUMBER OF EJECTOR STAGES/SUCTION PRESSURE
No. of stages Suction pressure (Torr)
1 100 ~ 760
2 20 ~200
3 4 ~40
4 0.5 ~1.0
5 0.05 ~1.0
6 under 0.05
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Ra, Kg MOTIVE STEAM PER Kg AIR LOAD
(ADD 20 PERCENT FOR TYPICAL SIZE CORRECTION FACTOR)
ESTIMATION CHART FOR STEAM EJECTOR
Fig. 9
6.2.2.5 Process specification sheet
Various forms of process specification (or data) sheets can be arranged for ordering ejectors or ejector vacuum systems. (See appendix E)
Regardless of the form of such sheets, the following data should be brought in the process specification or data sheet, for the vendor (or vendors), to be able to design the required system:
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1- Service.
2- Preferred Condenser Type.
3- Suction Pressure, mm Hg (abs.).
4- Suction Temperature, °C.
5- Maximum Discharge Pressure, mm Hg (abs.).
6- Steam: Min. Pressure, kPa(abs.).
Temperature, °C.
Quality, %.
7- Water: Source.
Max. Inlet pressure, kPa.
Max. Inlet Temperature, °C.
Max. Outlet Temperature, °C.
8- Volume of Evacuated System, m3.
9- Expected Air Leakage, kg/h.
10- Max. Evacuating Time, min.
11- Ejector Load:
a) Condensable: Water vapor and other vapors should be separately listed, and a heat curve for the vapors included if the system is of the condensing type.
- Rate, kg/h.
- Molecular Mass.
- Cp, kJ/(kg.K).
- Latent Heat, kJ/kg.
b) Non-Condensable:
- Rate, kg/h.
- Molecular Mass.
- Cp. kJ/(kg.K).
12- Corrosive Substance (if any), mol% .
7. VACUUM SAFETY
Safety around mechanical vacuum pumps is possibly no different than that for other process mechanical rotating machinery. However, there is a decided danger of an implosion (collapse) of a tank, reactor, other process equipment operating below atmospheric pressure if:
1) It is not designed to satisfy the ASME codes for total or “full” vacuum, regardless of the expected actual operating vacuum on the equipment, vessel, etc.
2) There are non or inadequate vacuum relief devices on the equipment or system being evacuated.
3) Block valves are installed to allow the blocking off of equipment (vessels, tanks, etc.) thereby pulling a higher vacuum than design, if not for “full” vacuum.
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APPENDICES
APPENDIX A
Example: Actual capacity for process vapor plus non-condensable
A distillation column is to operate with a horizontal overhead condenser, Fig. A.1, pressures are as marked. The estimated air leakage into the system is 4 kg/h. The molecular mass of the product vapor going out the condenser into the ejector (at 27°C) is 53. The vapor pressure of the condensing vapor is 3 mm Hg abs. at 27°C.
VACUUM SYSTEM FOR DISTILLATION Fig. A.1
Partial pressure air = 5 - 3=2 mm. Hg Vapor required to saturate at 27°C and 5 mm abs. total pressure:
7 53 3
10.96529 2
W M Pv nn kg hW VM Pn n
× ×= = =
×
Molar rate of air = 4/29 = 0.13793 kmol./h Molar rate of vapors = 10.965/53 = 0.20688 kmol/h Total molar rate = 0.13793 + 0.20688 = 0.3448 " "
( )4 10.96543.4
0.3448Average molecular mass
+= =
Molecular correction (from Fig. A.3) = 1.18 Air equivalent (at 27°C) = 14.965/1.18 = 12.68 kg/h Temperature correction (Fig. A.2, using air curve) = 0.999 21°C (70°F) air equivalent for mixture = 12.68/0.999 = 12.695 kg/h This is the value to be compared with a standard manufacturer’s test or performance curve at 21°C.
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TEMPERATURE ENTRAINMENT RATIO CURVE
Fig. A.2
MOLECULAR MASS ENTRAINMENT RATIO CURVE
Fig. A.3
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APPENDIX B
TYPICAL PIPING AND INSTRUMENT DIAGRAMS (P & IDS) AROUND VACUUM SYSTEMS
B.1 Steam Ejector Vacuum System
A Typical P & ID showing a vacuum system using steam ejector is shown in Fig. B.1.
Note that:
1 How the height of the condenser drain (seal) is specified. This height, in most cases is conventionally limited to be 15 m (min.).This is better shown in Fig. B.3.
2 Pressure in a vacuum system using steam ejectors can be controlled:
a) By introducing air or inert gas from outside,
b) By spilling back the motive steam, or,
c) By recycling the non-condensable gases in the system.
Methods (b) and (c) should be employed in such cases where noncondensable gases are definitely present in the system and the introduction of air into the system is not desirable or where the quantity of off-gas must not be increased.
In the case of Method (b), if non-condensable gases are not present in the system, the flow of the steam spilled back may be reversed to the equipment.
B.2 Vacuum Pump System
Fig. B.2 is a P & ID showing vacuum system using a liquid ring sealed vacuum pump. Method (a) in the figure is possible only in cases where non-condensable gases are present in the system.
TYPICAL P & I DIAGRAM FOR STEAM EJECTORS VACUUM SYSTEM
Fig. B.1
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TYPICAL P & I DIAGRAM FOR VACUUM PUMP SYSTEM
Fig. B.2
TYPICAL EJECTOR LAYOUT
Fig. B.3
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APPENDIX C
ESTIMATION OF POWER CONSUMPTION FOR VACUUM PUMPS
The kilowatts of all types of vacuum pumps may be estimated as follows:
1 Liquid ring Sealed Pumps:
BkW = 7.680 × (S.F.)0.924, S.F.= 0.05 - 35
2 Reciprocating Vacuum Pumps:
BkW = 3.974 × (S.F.)0.963, S.F.= 1.0 - 25
3 Rotary Piston Vacuum Pumps:
BkW = 4.242 × (S.F.)1.088, S.F.= 0.03 - 8
Where:
( )( )
2.2 × AiroVolume kg = hS.F.(Size Factors) =
operating pressure m Hg (Eq. C.1)
BkW = Breake Power in Kilowatts
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APPENDIX D
STANDARD EJECTOR UNITS DESIGNATIONS CONFORMING TO HEAT EXCHANGE INSTITUTE
Letter No. Position in Series
Normal Range of Suction Pressures (Hg. Abs.)
Normal Range of Disch. Pressures (Hg. Abs.)
Z Atmospheric stages 3"- 12" 30"- 32"
Y 1st of two stages .5''- 4" 1"- 10"
X 1st of three stages .1"- 1" 1"- 3"
W 1st of four stages .2 mm - 4mm 2 mm - 20 mm
V l st of five stages .02 mm - .4mm .4 mm - 3 mm
U 1st of six stages .01 mm - .08 mm .08mm - .4mm
The different types of condensing equipment used with the various series are identified by the following letters:
B- Barometric Counter- Flow Condenser, Intercondenser and Aftercondenser
C- Surface Coil Type Condenser and Aftercondenser.
S- Surface Type Condenser, Intercondenser and Aftercondenser
N-Signifies no condenser in the series
J-Atmospheric Jet Condenser, Intercondenser and Aftercondenser
The operating range of the condensing equipment determines the nomenclature. Here are the basic divisions.
Condenser 1.5" Hg-4" Hg abs
Intercondenser 4" Hg-10" Hg abs
Aftercondenser 30" Hg-32" Hg abs
By permission, Croll-Reynolds Co., Inc.
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STEAM JET ARRANGEMENTS WITH INTER-AFTER CONDENSERS. BY PERMISSION,
CROLL-REYNOLDS Co., Inc.
Fig. D.1
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APPENDIX E
TYPICAL EJECTOR DATA SHEET
BY:
PAGE: OF
DATA:
D.S. No.:
1 NUMBER 2 NAME 3 CASE 4 1ST STAGE INTER-CONDENSER SYMBOL 5 2ND STAGE INTER-CONDENSER SYMBOL 6 AFTER CONDENSER SYMBOL 7 NUMBER OF SETS REQUIRED 8 NUMBER OF SETS NORMALLY OPERATING PROCESS REQUIREMENTS 9 SUCTION FLUID DESCRIPTION 10 • NON-CONDENSIBLE RATE kg/hr 11 • NON-CONDENSIBLE MOL. WT. 12 • STEAM RATE kg/hr 13 • VAPOR RATE kg/hr 14 • VAPOR MOL. WT. 15 • TOTAL RATE kg/hr 16 • AVERAGE MOL. WT. 17 • OPERATING PRESSURE mm Hg 18 • OPERATING TEMPERATURE °C 19 DISCHARGE 20 • PRESSURE bara 21 • LOCATION DESIGN AND CONSTRUCTION
22 DATA ON SURFACE CONDENSERS 23 STEAM CONDITIONS FOR EJECTOR DESIGN 24 • MIN. MOTIVE STEAM PRESSURE bara 25 • DEGREES SUPERHEAT °C 26 27 EJECTOR MECH. DESIGN CONDITIONS 28 • DESIGN PRESSURE bara 29 • DESIGN TEMPRATURE °C 30 31
