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1、TECHNICAL SPECIFICATION FOULING RESISTANCES FOR HEAT TRANSFER EQUIPMENT DEP 20.21.00.31-Gen. December 1998 DESIGN AND ENGINEERING PRACTICE This document is confidential. Neither the whole nor any part of this document may be disclosed to any third party without the prior written consent of Shell Int
2、ernational Oil Products B.V. and Shell International Exploration and Production B.V., The Hague, The Netherlands. The copyright of this document is vested in these companies. All rights reserved. Neither the whole nor any part of this document may be reproduced, stored in any retrieval system or tra
3、nsmitted in any form or by any PDF created with pdfFactory Pro trial version means (electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owners. PDF created with pdfFactory Pro trial version PREFACE DEP (Design and Engineering Practice) p
4、ublications 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 Netherlands, and other Service Companies. They are based on the exper
5、ience 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 based on, or reference is made to, national and international sta
6、ndards 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 production facility, or any other such facility, and thereby to achieve m
7、aximum 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 cover every requirement or diversity of condition at each locality.
8、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 DEPs they shall be solely responsible for the quality of work and t
9、he 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 same level of integrity as reflected in the DEPs. If in doubt, the Co
10、ntractor 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 primarily with companies of the Royal Dutch/Shell Group and other com
11、panies 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 Company. The use of DEPs by these Operating companies is subject in all
12、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 contract with users referred to under 1) or 2) which requires that
13、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 users, SIOP, SIEP and SIC disclaim any liability of whatsoever natur
14、e 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 this disclaimer shall inure in all respects to SIOP, SIEP, SIC and
15、/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 prior written consent of SIOP and SIEP, be disclosed by users to an
16、y 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 express prior written consent of SIOP and SIEP. The copyright of DEPs
17、 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 queries should be directed to the DEP Administrator in SIOP. NOTE:
18、 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 their use. The above requirements for distribution and use of DEPs ar
19、e also applicable to Standard Specifications and DDDs. Standard Specifications and DDDs will gradually be replaced by DEPs. DEP 20.21.00.31-Gen. December 1998 Page 2 PDF created with pdfFactory Pro trial version TABLE OF CONTENTS 1.INTRODUCTION .4 1.1SCOPE 4 1.2DISTRIBUTION, INTENDED USE AND REGULA
20、TORY CONSIDERATIONS4 1.3DEFINITIONS 4 1.4CROSS-REFERENCES 5 1.5SUMMARY OF MAIN CHANGES5 2.APPLICABILITY AND BASIS OF THE DATA 6 2.1APPLICABILITY OF DATA6 2.2BASIS OF DATA6 3.APPLICATION OF LOWER FOULING RESISTANCES . 7 4.FOULING RESISTANCE TABLES .8 5.REFERENCES 33 APPENDICES APPENDIX 1COOLING WATER
21、 DATA.34 DEP 20.21.00.31-Gen. December 1998 Page 3 PDF created with pdfFactory Pro trial version 1.INTRODUCTION 1.1SCOPE This DEP specifies requirements and gives recommendations for establishing fouling resistance values for new unfired heat transfer equipment. It may also be used as a common basi
22、s for comparison of measured fouling rates. The fouling-resistance values given are based on average process conditions but shall be interpreted with judgement. This DEP is a revision of the DEP of the same number dated April 1981; a summary of the main changes is given in (1.5). 1.2DISTRIBUTION, IN
23、TENDED USE AND REGULATORY CONSIDERATIONS Unless otherwise authorised by SIOP and SIEP, the distribution of this DEP is confined to companies forming part of the Royal Dutch/Shell Group or managed by a Group company, and to Contractors and Manufacturers/Suppliers nominated by them (i.e. the distribut
24、ion code is “F“ as defined in DEP 00.00.05.05-Gen.). This DEP is intended for use in oil refineries, chemical plants, gas plants, exploration and production facilities and supply/marketing installations. If national and/or local regulations exist in which some of the requirements are more stringent
25、than in this DEP, the 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 t
26、he requirements of this document 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. 1.3DEFINITIONS 1.3.1Genera
27、l 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 or maintenance of a facility. The Principal may undertake all or part of the duties of the Contractor. The Manufacture
28、r/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 will generally specify the technical requirements
29、. 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. DEP 20.21.00.31-Gen. December 1998 Page 4 PDF created with pdfFactory Pro trial version 1.3.2Specific d
30、efinitions Fouling resistancea measure of the ultimate additional resistance to heat transfer caused by deposits on and corrosion of the heat transfer material surface. The fouling resistance depends on the type of fluid, the heat-transfer surface material, the temperatureconditions,theflowvelocitie
31、sandthe operating period between two successive cleaning actions. Fouling coefficientthe reciprocal of the fouling resistance. NOTE:Theuseofthefoulingcoefficienthasgenerallybeen abandoned, since it tends to be confusing that an increase in fouling results in a decrease in the fouling coefficient. 1.
32、4CROSS-REFERENCES Where cross-references to other parts of this DEP are made, the referenced section number is shown in brackets. Other documents referenced in this DEP are listed in (5). 1.5SUMMARY OF MAIN CHANGES A summary of the main, non-editorial, changes since the last revision of this DEP are
33、 as follows: SectionDescription 2.3Explains the types of heat exchangers for which the listed fouling resistances apply 3.Recommended cooling water velocity now varies depending on tube material 5.Values of fouling coefficient have been removed (explained in the definition in 1.3.2) Table 4-amended
34、for cracked residues Table 20 -more fluids included Table 21 -new table for LNG plants Appendix 1Frictional pressure drops included for cooling water DEP 20.21.00.31-Gen. December 1998 Page 5 PDF created with pdfFactory Pro trial version 2.APPLICABILITY AND BASIS OF THE DATA 2.1APPLICABILITY OF DAT
35、A Fouling resistance values apply for shell and tube heat exchangers for both shell-side and tube-side fluids as well as for fluids flowing on tube side of air-cooled heat exchangers. Other types of heat exchangers, non tubular, are not normally designed with these fouling resistance values. 2.2BASI
36、S OF DATA The values given in (4) are the result of experience and common practice. Tables 1 to 21 are grouped by type of processing unit, since it is impossible to make a proper evaluation of all variables which affect fouling. Table 22 gives values for water and steam. The values given are based o
37、n the assumption that flow velocities, temperature and fluid conditions are comparable in similar units. The listed values generally do not take into account: a) the effect of shell-side or tube-side flow; b) the effect of flow velocities; c) temperature limitations. a) For products containing sedim
38、ents, cracked products and other unstable materials containingforexamplepolymers,tube-sideflowispreferred.Foulingismore pronounced on the shell side of heat exchangers than on the tube-side flow because of dead corners and the effect of bundle bypassing. Therefore for these products the values given
39、 are for tube-side flows only, if not otherwise stated. b) *Flow velocities of fluids should be chosen as high as compatible with process requirements and acceptable power consumption, having regard to the effect of erosion and corrosion caused by this velocity. This may be aggravated by the presenc
40、e of sediments. For tube-side flow the velocity should be not less than 1.0 m/s; for shell-side flow the effective velocity (taking due account of bypass streams) should be not less than 0.5 m/s. Shell-side velocities can often be improved by the installation of more shells in series. For cooling wa
41、ter the preferred tube-side flow velocity depends on the tube material as shown in Appendix 1. The minimum allowed velocities are also given in Appendix 1. c) *For cooling water, either from a cooling tower or a once-through system, the maximum water-side skin temperature in clean condition shall be
42、 not higher than 52 C (in view of increased fouling tendency), unless otherwise specified. *For those exchangers where definite restrictions are applicable with regard to maximum or minimum skin temperature and minimum or maximum flow velocity, this shall to be specified in the applicable process sp
43、ecification and data/requisition sheets. DEP 20.21.00.31-Gen. December 1998 Page 6 PDF created with pdfFactory Pro trial version 3.APPLICATION OF LOWER FOULING RESISTANCES Lower fouling resistances may be appropriate if one or more of the circumstances described below apply. However, such lower val
44、ues may be applied only where specifically approved by the Principal. In services where the surface requirements are significantly influenced by the degree of fouling, it may be advantageous to specify a lower resistance if a reduced period between two successive shutdowns is feasible. This can be a
45、chieved for instance by the installation of a spare exchanger in parallel with the one in operation, thus enabling cleaning at any time without plant shutdown. This is especially important where controllability/stability is influenced by fouling, e.g. in thermo-syphon reboilers. The maximum allowabl
46、e pressure drop generally limits the fluid velocity. This means that for designs where low pressure drops have to be applied the fluid velocities will often become low. When the specified fouling resistance is high, resulting in the installation of considerable over-surface in clean condition, the m
47、aximum attainable velocity may reduce appreciably. This, in turn, will increase the tendency of fouling. By taking a lower fouling resistance, a smaller heat exchanger will be adequate, thus making it possible to apply a higher velocity and still stay within the limits of allowable pressure drop. NO
48、TE:The selection of lower fouling resistances should be done with due regard to the drive to longer periods between shutdowns. DEP 20.21.00.31-Gen. December 1998 Page 7 PDF created with pdfFactory Pro trial version 4.FOULING RESISTANCE TABLES TableTitle 1Distillation units 2Luboil plants 3Hydroproc
49、essing units 4Conversion units 5Ethylene plant 6Ethylene oxide plant 7Cumene plant 8Phenol plant 9Di-phenylol propane plant 10Epikote plant 11C3= solvent plant 12C4= solvent plant 13Butadiene plant 14Sulfolane plant 15Aromatics plant 16Xylenes plant 17Urea wax plant 18Wax cracking unit 19Luboil hydrocracking unit 20Treating units 21Liquefied natural gas plant 22Values for water and steam DEP 20.21.00.31-Gen. December 1998 Page 8 PDF created with pdf