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1、MANUAL GLYCOL-TYPE GAS DEHYDRATION AND HYDRATE INHIBITION SYSTEMS DEP 20.04.10.10-Gen. December 1994 (DEP Circulars 42/96 and 16/99 have been incorporated) DESIGN AND ENGINEERING PRACTICE USED BY COMPANIES OF THE ROYAL DUTCH/SHELL GROUP This document is confidential. Neither the whole nor any part o
2、f this document may be disclosed to any third party without the prior written consent of Shell Internationale Petroleum Maatschappij B.V., The Hague, the Netherlands. The copyright of this document is vested in Shell Internationale Petroleum Maatschappij B.V., The Hague, the Netherlands. All rights
3、reserved. Neither the whole nor any part of this document may be reproduced, stored in any retrieval system or transmitted in any form or by any means (electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owner. PDF created with pdfFactory
4、Pro trial version PREFACE DEP (Design and Engineering Practice) publications reflect the views, at the time of publication, of: Shell International Oil Products B.V. (SIOP) and Shell International Exploration and Production B.V. (SIEP) and Shell International Chemicals B.V. (SIC) The Hague, The Net
5、herlands, and other Service Companies. They are based on the experience acquired during their involvementwith the design, construction, operation and maintenance of processing units and facilities, and they are supplemented with the experience of Group Operating companies. Where appropriate they are
6、 based on, or reference is made to, national and international standards and codes of practice. The objective is to set the recommendedstandard for good design and engineeringpractice applied by Group companies operating an oil refinery, gas handling installation, chemical plant, oil and gas product
7、ion facility, or any other such facility, and thereby to achieve maximum technical and economic benefit from standardization. The information set forth in these publications is provided to users for their consideration and decision to implement. This is of particular importance where DEPs may not co
8、ver every requirement or diversity of condition at each locality. The system of DEPs is expected to be sufficiently flexible to allow individual operating companies to adapt the information set forth in DEPs to their own environment and requirements. When Contractors or Manufacturers/Suppliers use D
9、EPs they shall be solely responsible for the quality of work and the attainment of the required design and engineering standards. In particular, for those requirements not specifically covered, the Principal will expect them to follow those design and engineering practices which will achieve the sam
10、e level of integrity as reflected in the DEPs. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from his own responsibility, consult the Principal or its technical advisor. The right to use DEPs is granted by SIOP, SIEP or SIC, in most cases under Service Agreements pri
11、marily with companies of the Royal Dutch/Shell Group and other companies receiving technical advice and services from SIOP, SIEP or SIC. Consequently, three categories of users of DEPs can be distinguished: 1)Operating companies having a Service Agreement with SIOP, SIEP, SIC or other Service Compan
12、y. The use of DEPs by these Operating companies is subject in all respects to the terms and conditions of the relevant Service Agreement. 2)Other parties who are authorized to use DEPs subject to appropriate contractual arrangements. 3)Contractors/subcontractors and Manufacturers/Suppliers under a c
13、ontract with users referred to under 1) or 2) which requires that tenders for projects, materials supplied or - generally - work performed on behalf of the said users comply with the relevant standards. Subject to any particular terms and conditions as may be set forth in specific agreements with us
14、ers, SIOP, SIEP and SIC disclaim any liability of whatsoever nature for any damage (including injury or death) suffered by any company or person whomsoever as a result of or in connection with the use, application or implementation of any DEP, combination of DEPs or any part thereof. The benefit of
15、this disclaimer shall inure in all respects to SIOP, SIEP, SIC and/or any company affiliated to these companies that may issue DEPs or require the use of DEPs. Without prejudice to any specific terms in respect of confidentiality under relevant contractual arrangements, DEPs shall not, without the p
16、rior written consent of SIOP and SIEP, be disclosed by users to any company or person whomsoever and the DEPs shall be used exclusively for the purpose for which they have been provided to the user. They shall be returned after use, including any copies which shall only be made by users with the exp
17、ress prior written consent of SIOP and SIEP. The copyright of DEPs vests in SIOP and SIEP. Users shall arrange for DEPs to be held in safe custody and SIOP or SIEP may at any time require information satisfactory to them in order to ascertain how users implement this requirement. All administrative
18、queries should be directed to the DEP Administrator in SIOP. NOTE: In addition to DEP publications there are Standard Specifications and Draft DEPs for Development (DDDs). DDDs generally introduce new procedures or techniques that will probably need updating as further experience develops during the
19、ir use. The above requirements for distribution and use of DEPs are also applicable to Standard Specifications and DDDs. Standard Specifications and DDDs will gradually be replaced by DEPs. DEP 20.04.10.10-Gen. December 1994 Page 2 PDF created with pdfFactory Pro trial version TABLE OF CONTENTS 1IN
20、TRODUCTION .5 1.1SCOPE 5 1.2DISTRIBUTION, APPLICABILITY AND REGULATORY CONSIDERATIONS 6 1.3DEFINITIONS 7 1.4SYMBOLS AND ABBREVIATIONS .11 1.5CROSS-REFERENCES 15 2PROCESS DESCRIPTION OF GAS DEHYDRATION 16 2.1BASIC FLOW SCHEME 18 2.2COLDFINGER .20 2.3VACUUM .21 2.4GAS STRIPPING .22 2.5AZEOTROPIC STRIP
21、PING .23 2.6ACID GAS SOLUBILITIES AND STRIPPING 24 2.7DEHYDRATION OF CO2 25 2.8MERCURY IN THE FEED GAS.27 2.9PROCESS VARIABLES 28 3DESIGN GUIDELINES FOR GAS DEHYDRATION SYSTEMS 30 3.1INLET GAS COOLER31 3.2INLET GAS SEPARATOR .32 3.3CONTACTOR33 3.4GLYCOL REGENERATOR41 3.5HEAT EXCHANGERS .49 3.6SURGE
22、DRUM 54 3.7GLYCOL FLASH VESSEL.55 3.8CONDENSED OVERHEADS SEPARATOR .56 3.9FILTERS57 3.10GLYCOL CIRCULATION PUMPS .59 3.11PIPING, VALVES AND FITTINGS.60 3.12COLDFINGER .62 3.13GAS STRIPPING .63 3.14AZEOTROPIC STRIPPING (DRIZO).65 3.15ELECTRICAL REQUIREMENTS .66 3.16MECHANICAL REQUIREMENTS .67 4UPGRAD
23、ING OF GAS DEHYDRATION SYSTEMS. 69 4.1INLET SEPARATION 69 4.2CONTACTOR69 4.3GLYCOL REGENERATION CIRCUIT .70 5OPERATION AND MAINTENANCE OF GLYCOL DEHYDRATION SYSTEMS 71 5.1PERFORMANCE CONSIDERATIONS 71 5.2OPERATING PROBLEMS.74 5.3START-UP AND SHUT-DOWN PROCEDURES.75 5.4MAINTENANCE.75 6DESCRIPTION OF
24、PROCESSES FOR HYDRATE INHIBITION 76 6.1FLOW SCHEME FOR AN LTS PROCESS WITH EXPANSION VALVE . 77 6.2FLOW SCHEME FOR AN LTS PROCESS WITH MECHANICAL REFRIGERATION .77 6.3FLOW SCHEME FOR LTS PROCESS WITH TURBO-EXPANDER . 77 6.4FLOW SCHEME FOR A WET GAS PIPELINE78 6.5FLOW SCHEME FOR GLYCOL REGENERATION 7
25、8 7DESIGN GUIDELINES FOR HYDRATE INHIBITION SYSTEMS . 79 DEP 20.04.10.10-Gen. December 1994 Page 3 PDF created with pdfFactory Pro trial version 7.1INJECTION SYSTEMS79 7.2COLD LIQUID HEATERS81 7.3CONDENSATE/GLYCOL SEPARATION 81 7.4GLYCOL REGENERATION.83 7.5PARTICLE FILTERS .83 7.6GLYCOL PUMP FOR CO
26、LD LIQUID PRE-HEATER 84 7.7GLYCOL STORAGE84 8UPGRADING OF HYDRATE INHIBITION SYSTEMS 85 8.1INLET SEPARATION 85 8.2INJECTION SYSTEM 85 8.3TYPE OF GLYCOL85 9OPERATIONS AND MAINTENANCE OF HYDRATE INHIBITION SYSTEMS 86 9.1GLYCOL SOLUTION PROBLEMS 86 9.2HYDRATE BLOCKAGE .86 9.3GLYCOL LOSSES.87 10PROCESS
27、CONTROL AND SAFEGUARDING 88 10.1GLYCOL CONTACTOR 88 10.2FLASH VESSEL 89 10.3REGENERATOR .89 10.4ALARMS AND INDICATIONS .90 10.5PROCESS SAFEGUARDING91 11REFERENCES 92 12BIBLIOGRAPHY .95 FIGURES.96 APPENDICES APPENDIX IPROPERTIES OF GLYCOLS.138 APPENDIX IIGLYCOL FOAM CONTROL TEST.147 APPENDIX IIITESTI
28、NG OF GLYCOL QUALITY 149 APPENDIX IVEVALUATING THE RESULTS OF GLYCOL SAMPLE TESTING 150 APPENDIX VTROUBLESHOOTING GAS DEHYDRATION SYSTEMS 152 APPENDIX VISTART-UP AND SHUT-DOWN PROCEDURES FOR GAS DEHYDRATION SYSTEMS .154 APPENDIX VIIMAINTENANCE OF GAS DEHYDRATION SYSTEMS 157 DEP 20.04.10.10-Gen. Dece
29、mber 1994 Page 4 PDF created with pdfFactory Pro trial version 1INTRODUCTION 1.1SCOPE This is a new DEP which gives guidance and procedures for the design, material selection, fabrication,operationand maintenance of glycol-typegas dehydrationand hydrate inhibition systems for: -onshore and offshore
30、 locations; -sweet and sour service; -operating temperatures above -40 C. Gas dehydration and hydrate inhibition, based primarily on TEG and MEG respectively, are addressed in this DEP because of the many areas of commonality. Sections on gas dehydration precede those on hydrate inhibition with only
31、 the latter containing cross- references. There is only one industry standard which partly covers the scope of this DEP, i.e. API specification 12GDU for (onshore) Glycol-Type Gas Dehydration Units. Since its approach and recommendations often conflict with this manual, leaving few areas of agreemen
32、t, it is not further referenced and therefore should not be used. This DEP discusses the merits of and offers design guidelines for different dehydration processes. It is beyond the scope of this DEP to give specific recommendations for selection of a particular process. DEP 20.04.10.10-Gen. Decembe
33、r 1994 Page 5 PDF created with pdfFactory Pro trial version 1.2DISTRIBUTION, APPLICABILITY AND REGULATORY CONSIDERATIONS Unless otherwise authorised by SIPM, the distribution of this DEP is confined to companies forming part of, or managed by, the Royal Dutch/Shell Group, and to Contractors nominat
34、ed by them (i.e. the distribution code is “C“ as defined in DEP 00.00.05.05-Gen.). This DEP is intended for use in associated and non-associated gas production and treatment facilities. If national and/or local regulations exist in which some of the requirements are more stringent than in this DEP t
35、he Contractor shall determine by careful scrutiny which of the requirements are the more stringent and which combination of requirements will be acceptable as regards safety, economic and legal aspects. In all cases the Contractor shall inform the Principal of any deviation from the requirements of
36、this DEP which is considered to be necessary in order to comply with national and/or local regulations. The Principal may then negotiate with the Authorities concerned with the object of obtaining agreement to follow this DEP as closely as possible. DEP 20.04.10.10-Gen. December 1994 Page 6 PDF crea
37、ted with pdfFactory Pro trial version 1.3DEFINITIONS 1.3.1General definitions The Contractor is the party which carries out all or part of the design, engineering, procurement, construction, commissioning or management of a project or operation of a facility. The Principal may undertake all or part
38、 of the duties of the Contractor. The Manufacturer/Supplier is the party which manufactures or supplies equipment and services to perform the duties specified by the Contractor. The Principal is the party which initiates the project and ultimately pays for its design and construction. The Principal
39、will generally specify the technical requirements. The Principal may also include an agent or consultant authorised to act for, and on behalf of, the Principal. The word shall indicates a requirement. The word should indicates a recommendation. 1.3.2Specific definitions AbsorberSee contactor Absorpt
40、ion ProcessThe attraction and retention of vapours (water) by liquids (glycol) from a gas stream. Actual TraysThe number of trays installed in a column or the equivalent number of actual trays for a packed column. Bubble Cap TrayHorizontal plate holding bubble caps and downcomers in the contactor. B
41、ubble CapsSlotted metal caps attached over elevated nozzles (risers) on the bubble cap trays. The slots cause the gas to break up into small bubbles for intimate contact with the glycol. CondensateLight hydrocarbon liquids. Contactor (or Absorber)A vertical pressure vessel where gas and glycol are i
42、ntermingled counter-currently to remove water vapour from the gas. The contactor usually contains bubble cap trays, valve trays or structured packing. DehydrationRemoval of water vapour from a gas. Design PressureThe pressure used in the design of a vessel for the purpose of determining the minimum
43、permissible wall thickness or physical characteristics of the different parts of the vessel. DewpointThe temperature at which vapour begins to condense into a liquid at a particular system pressure. A natural gas stream exhibits both DEP 20.04.10.10-Gen. December 1994 Page 7 PDF created with pdfFact
44、ory Pro trial version hydrocarbon and water dewpoints. Dewpoint DepressionThe difference in water dewpoint temperature between the gas entering and leaving the contactor. DowncomerThe vertical conduit between trays which allows liquid to pass from tray to tray. FloodThe condition wherein excess liq
45、uid hold-up occurs and normal counterflow action is prevented in the glycol contactor, regeneration still or stripping column. It is a design limit which when reached in operation causes an excessive loss of liquid from the top of the column. Free WaterLiquid water which is not dissolved in any othe
46、r substance. Gas/Glycol Heat ExchangerA heat exchanger employed to cool the lean glycol by the gas leaving the contactor before the glycol enters the contactor. GlycolA hygroscopic liquid. Mono-ethylene Glycol (MEG) and Di-ethylene Glycol (DEG) are commonly used in hydrate inhibition service and Tri
47、-ethylene Glycol (TEG) is most common in gas dehydration service. Lean Glycol (or Dry Glycol)Glycol which has been regenerated and has a low water content. Rich Glycol (or Wet Glycol)Glycol which has absorbed water and thus has a high water content. Glycol Flash SeparatorA two or three phase separat
48、or which is used in the rich glycol stream to remove entrained gas and hydrocarbon liquids. Glycol/Glycol ExchangerA heat exchanger employed to recover heat from the outgoing hot lean glycol from the reboiler and for pre-heating the incoming cool rich glycol from the contactor. Heat DutyThe rate of
49、heat absorption by the process. Heat FluxThe average heat transfer rate through the heat exchanger tube, to the fluid. HydrateA clathrate compound formed by a combination of methane, ethane, propane, iso-butane, H2S or CO2and free water at elevated pressure and low temperature. Hydrate InhibitorA chemical (e.g. glycol, methanol) which DEP 20.04.10.10-Gen. December 1994 Page 8 PDF created with pdfFactory Pro trial version depresses the hydrate formati