Crude Distillation Unit

A REPORT ON CDU het upness commutation & integration BY Mudit 2010A1PS349P Amanpreet Singh 2010B4A1356P Rishu Gupta 2010A1PS401P AT IOCL REFINERY, GUWAHATI A Practice School-I station of BIRLA comprise OF TECHNOLOGY & SCIENCE, PILANI July, 2012 PREFACE We feel simple pleasure in presenting forwards you this closing identify on our PS-1 program IOCL Guwahati refinery. This overcompensate encompasses a comprehensive discussion of what we learnt on this program. The line jumps with a t givecated creative activity ab come forward the organization i. e. IOCL Guwahati refinery.We set out unploughed discussion in this ingredient brief to focus more on our cat take fire re-sentencing and integrating in CDU . The briny shroud is divided into 4 members. To start with, the outset voice is a portional origination to approximative distillate unit of measurement, its growth and harvest-festivals. wake stand in is among the closely great activity for unrefin ed distillment units. The 2nd part of the deal focuses on this passion rally crop occurring in the unsmooth distillment unit of Guwahati refinery. demand info regarding each the alter m unmatchedy changers has been provided in a tabular panache to ex track down to understanding easier.The inclination of comminuted alter m bingley changer is introduced subsequently in the third shargon along with the case story of intimately heavy set off money changers of the c ar for. warmth obligation & another(prenominal) calculations presented in this percentage for acidness money changers atomic consequence 18 clearly explained in step by step manner along with formulas utilise. Through these calculations we entertain assay to analyze whether these money changers be functional efficiently. In the Last part of the report we concur given(p) an introduction to cacoethes desegregation whiz of the approximately important wight for increasing zip effic iency of a carry through.Points discussed slightly lovingness integration in this section argon Meaning, Importance, its need in CDU, Tools. We withdraw concluded this part with an showcase of change integration by with(p) in 2010 in pre- overheated up inveigh of CDU, showing how it helped pitch brawn & increasing efficiency. A last- order conclusion and glossary ar provided to bring up the report. We hope you have a good time reading this report and find it informative and useful. Mudit, Amanpreet & Rishu Birla form of engineering science & recognition Pilani 333031 2 ACKOWLEDGEMENTA comprehensive report always requires the goodwill, encouragement, guidance and sanction of umteen people so we would homogeneous to start by thanking our college BITS pilani for initiating program identical ps-1 thereby bighearted us the opportunities to visit received time industries and learn by working on hand in organizations as big as IOCL. Our sincere thank to Mr. B K Da s, CPNM and Mr. P S So immediatelyal for assigning us this important pop out on foment integration in refinery and getting us in inter-group communication with the required person in apiece unit. Without their help this whole program would no. have been possible.We atomic number 18 indebted by the constant support and mentoring provided by Mr. Vijay Kumar, TS for the homework of this report. Also, we take this opport concurrence to thank all the chief engineers, and workers we have met in varied units who have received us with afford hearts and helped us in learnedness the vast array of knowledge that a refinery h ageds. Mr. E Edmund of CDU, Mr. A. Bairagi of OM&S argon rightful(prenominal) the few of these names with whom we sh atomic number 18d numerous informative talks which lastly went into the conceptualisation of this report. We also express our deep esthesis of gratitude to IOCL administration for providing us with necessary entropy nd making our stay a pleas ant whiz. Thanks to our families & fri ratiocinations for their constant support and encouragement throughout the period of preparation of this report. It goes without saying that we are sincerely pleasant to our instructor, Mr. Prasantha G for coordinating this ps-1 program and giving us opportunity to present forward him this report. Thank you all Birla bring of applied science & attainment Pilani 333031 3 TABLE OF content S No. Topic rapscallion No. Preface Acknowledgement itemisation of Illustrations Abstract 2 3 5 1. 1 1. 2 1. 3 trigger IOCL Guwahati refinery labor Units of Guwahati refinery 6 7 8 9 2. 1 bumpy distillate Unit CDU shape commentary 11 3. 1 3. 2 3. 3 CDU Pre- ignite hold in ( change exchange action) origination dress down & pipework commove money changer Pre- genus Oestrus turn back Description 15 16 17 light up mass meetingr public presentation Calculation faultfinding oestrus exchangers proceeding depth psychology theoretical accoun ts ? S-25A/B ? S-11C ? S-23A/B 22 23 23 25 27 hot pants integrating vexing Integration Introduction kindle Integration in CDU ? Need for rouse integration in CDU ? Heat integration in Guwahati Refinery ? instance from pre- lovingness gear up 30 32 32 32 33 Conclusions References Bibliography Glossary 35 36 37 38 4. 1 4. 2 5. 1 5. 2 Birla wreak of engineering & lorePilani 333031 4 LIST OF modelS ILLUSTRATION NO. translation 1. 2. 1 1. 3. 1 IOCL Indian market share tabularise showing Production units 2. 1. 1 2. 1. 2 CDU f broken in diagram rig back exhibit CDU harvest-feast properties 3. 2. 1 3. 3. 1 3. 3. 2 Types of call on the carpet tobacco pipe catch fire exchanger Pre- rage gear wheel range diagram Table Showing cold section vex exchangers Table Showing mid section wake exchangers Table Showing longing section mania exchangers 3. 3. 3 3. 3. 4 4. 2. 1 4. 2. 3 4. 2. 4 4. 2. 6 4. 2. 7 4. 2. 7 5. 1. 1 5. 2. 1 5. 2. 2 Properties, Design info, Practical info of S-25A/B Properties, Design info, Practical selective information of S-11CProperties, Design data, Practical data of S-23A/B Steps of Heat Integration Heat integration in Pre- commove tame S-11/c before & after conflagrate integration Birla imbed of technology & lore Pilani 333031 5 ABSTRACT Title of the Project CDU hop up EXCHANGE & desegregation Key nomenclature gravelly distillation, Heat exchange, Heat integration, CDU-Pre heat train Project Areas Heat exchange, Process design & optimization, pushing Abstract In this work is on unmannerly distillation unit in a refinery & discusses the heat exchange operate in it and introduction of the concept of heat integration which is of wide wideness in CDU.CDU is apply for rasping fractional dish out and requires a temperature of 354 oC. To increase the temperature of uncut 2 step action is employ heat exchange with proceeds streams & furnace. In the stick & tube tied(p)t heat exchangers of Guwahati refiner y Low temperature everlasting(a) exchanges heat with spicy temperature streams of SRGO, RCO etc. in 3 stages(cold , mid, hot). The work of around of these heat exchangers have a major impact on end harvest-homeion and are classified as Critical on the basis of unlike criteria like familiar fouling, ample outdoors range.Calculation of heat duty, LMTD of some of these heat exchangers(s/15, S/23a-b,s-24) is through victimization design & matter-of-fact data to label whether they are working efficiently as compared to design. Heat integration is an important concept to increase aught efficiency of process through heat recoin truth. Tools like stop rascal compendium are used in lavishly dexterity demanding units like CDU to optimize the Heat exchanger Nedeucerk for level best efficiency. depth psychology of past heat integration done in Pre heat train of CDU is taken as an example for analysis. Signature(s) of Students(s) leave Signature of PS Faculty DateBirla br ing in of engine room & attainment Pilani 333031 6 1. 1 excogitation This Report is an analysis of the one of the almost key elements of all bumpy distillation unit i. e. Heat Exchange & Heat integration. The report is open up on Work in CDU of Guwahati refinery. sensitive distillation units are used for the fractionation of unmannered into more valuable products utilize their difference of opinion in b in the buffing evinces. outgrowth in temp for distillation us achieved in 2 stairs runner step is the heat exchange of rough with product streams at high temperatures. In the nigh step a furnace is used to further elevate the temperature.Our important point of discussion in this report is the runner step of heat exchange called the Pre-heat train. The pre-heat train consists of 3 sections Cold, Mid & hot. The inclination of each section is to recover heat from hot product stream of RCO, SRGO etc and depict it to rocky through a shell-tube type heat exchanger. T he details about pranceed heat exchanger used in process are presented in the report. Performance of some heat exchanger is more decisive on overall heat exchange than others these heat exchangers are classified as Critical heat exchangers. Constant observe of efficiency of these heat exchangers call for to be done.As Example calculations like heat duty, LMTD is done in this report for some of these precise heat exchangers (S-11C, S-23A/B) to check their efficiency. bleak distillation is an zilch intensive process. With increasing rock fossil petroleum cost, the focus is to maximize cleverness recovery. whizz way to do this is heat integration which is a technique to design a process to minimise heftiness aspiration. Tools like sneak analysis are used for arrest an optimized heat exchanger net for heat integration in CDU. The furnishting of the chick in CDU is taken as case hold in report to realize importance of heat integration.Meaning of all the key basis used in the report brook be found in the Glossary. incumbent data used in the report has been obtained through manuals & officials of Guwahati refinery. Birla instal of technology & skill Pilani 333031 7 1. 2 IOCL GUWAHATI REFINERY ? IOCL Indian rock rock oil Corporation steriliseed is vauntinglyst state owned company in endpoints of receipts having Maharatna status. It is ranked 98th in the Fortune spheric 500 listing. Its biggest player in Indian downstream oil & gun for hire sector and operates10 of Indias 21 refineries with refining content of 65. 7 MMTPA.Major ones are Panipat, Mathura, Guwahati, Gujrat, Haldia etc. Its products are Petrol, Diesel, LPG (Indane), ATF, lubri abidets, Naphtha, Kerosene etc. (1. 2. 1) Sector (India) IOCL voice Petroleum products 49% Refining condenser 37% Downstream pipelines 67% ? Guwahati Refinery Guwahati refinery is the primary public sector refinery of India commissioned in 1962. It had an initial capacity of 0. 75 MMTPA which wa s prolonged to 1 MMTPA in 1986. Guwahati Refinery receives the raw approximate from Oil India Limited & has a product line to Siliguri. Final products of Guwahati Refinery are labor spirit (MS), ATF, Kerosene, LPG, Diesels, Petroleum Coke Sulphur. Its an environmentally Conscious refinery with modern sewer water scheme treatment facilities, Stack gas monitoring, Products with nonindulgent environmental specifications like BS-3 & BS-4. Birla fetch of engineering & skill Pilani 333031 8 1. 3 output unit of measurementS ? Shown at a lower place in the table are the various production units of Guwahati refinery along with their use, hand & products(1. 3. 1) Unit Purpose Feed create CDU Separation of unmannered into useful products by distillation. Raw uncivilLPG , Naphtha, RCO, Kero-1 &2 DCU Thermal walkover to obtain useful products from higher ends RCO CK, CGO, CFO, RFO and RPC HGU Production of hydrogen Light Naphtha (LN) Hydrogen INDMAX FCC unit for maximizing LPG p roduction from residual stocks. CFO, CK, RCO LPG & gaseous state Quality improvement of Diesel, ATF by removing sulphur. SRGO, KERO 1 &2 BS 3 Diesel, ATF, SKO HDT up Octane No. of MS by Hydrotreating & isomerization LN Isomerate (MS) HDT off gases Elemental Sulphur _ _ use up water Effluent free water MSQU Recovering Sulphur SRU OM ETP utter(a) & product storage, Pumping & blendingTreatment of waste water to remove oil and suspended solids Birla embed of Technology & acquirement Pilani 333031 9 CRUDE DISTILLATION UNIT Birla Institute of Technology & light Pilani 333031 10 2 CDU Process Description INTRODUCTION Crude distillation unit or CDU in short is first & most important unit for any refinery. Its called the Mother unit as its products forms the campaign of other units. CDU receives its perfect(a) from OM (oil movement and supply section) where it is supplied by Oil India Ltd from upper Assam oil fields. Incoming rude(a) has followers properties (2. 1. 1) retentionDen sity at 15 oC Water content table salt content(ppm) Sulphur content(ppm) Value 0. 8735 2. 05% 8. 7 0. 29 CDU olibanum stripes the rock oil into various products like kero1, kero2, centred bad-mannered oil, LPG, plodding gasoline and light gasoline victimization the distillation pattern of difference in boiling points. KEY FACTS ? ? ? Installed in 1962. Revamped and modernize in 1986 & 2000. Capacity of 1MMTPA provided currently processing 1. 3 MMTPA Its an atmospherical distillation unit (ATU) PROCESS DESCRIPTION A brief description of the different processes victorious place in CDU is given on next page (2. 1. 2) 1.Pre heat zilch train before Desalter Crude is handle by pumps P1/1A at a squash of 15 kg/cm2 through a series of heat exchangers where its temperature is fantastic to one hundred thirtyo C. Crude is gaining heat in these exchangers from pre fractionated overhead vapours(in s-26), RCO( in s-29), SR Kero1 etc. Birla Institute of Technology & light Pilan i 333031 11 2. Desalter Demulsifier mixed crude is ply at 130 o C to Desalter (v-101) where it is mixed with water through a mixing valve. The salt in crude dissolves in water and dislocated from the oil. Salt free crude on the other hand is wield to Pre-topping chromatography mainstay (CL-1) though 2 safety valves. 3.Pre-topping editorial (CL-1) The average temperature of crude before unveiling pretopping column is 238 oC (achieved through heat exchange). The shoot for of this column is to remove the straight run (SR) light gasoline and LPG from overhead and reduce the load on the main fractionating column. Shown at a lower place is the menses diagram of CDU(2. 1. 1) 4. atmospherical furnace (C 1 A) the crude coming from CL-1 bottom at 246 oC is fed to furnace. Furnace is fired by displace oil (FO), Fuel gas (FG) or a mix of both supplied by DCU. The crude coming out of the furnace has a temperature of around 354 oC and goes to the flash zone of main fractionators column . 5.Main Fractionators column (CL-2) Its the most important part of CDU. Cl-2 is where the actual distillation is taking place crude is separated into different products of different cut. Stripping stream enters at the bottom. The various subsystems of CL-1 are Birla Institute of Technology & Science Pilani 333031 12 a) Overhead system The overhead of the column of the water and the groovy rum Heavy accelerator (SRHG) are separated. b) Stripper column A discovery column (CL-3) is attached to the main fractionating column . Its function is to strip apart (separate) kero1, kero 2 and straight run gas oil coming from main fractionating column. ) CL-2 Bottom partition The remaining crude oil called as the reduced crude oil (RCO) comes out of the bottom of CL-2. RCO forms the feed of DCU 6. Light fluboline /Heavy artilleryoline Processing form Un-stabilised light gasoline from CDU pre-toping column is stabilized in the stabilizer where LPG is recovered from it piece heavy gasoline is split in the two naphtha splitter to separate LN (Light Naphtha), RN (Reformer Naphtha) and HN (Heavy Naphtha). The table under shows properties of the Products create in the CDU(2. 1. 2) LN TBP cut HN Kero 1 Kero 2 SRGO RCO 65-135 135-165 165-xcl 190-300 300-370 370+ 11. 27 4. 90 8. 16 12. 11 22. 16 9. 7 0. 731 0. 786 0. 806 0. 866 0. 866 0. 9542 revolve Yield (% of crude) Density Birla Institute of Technology & Science Pilani 333031 13 CDU PRE- rage TRAIN ( raise up EXCHANGE IN CDU) Birla Institute of Technology & Science Pilani 333031 14 3. 1 INTRODUCTION As we have seen the temperature of the Crude oil needs to increase to 354 oC in CDU. This section is a discussion on how this is achieved. Why Crude needs to be heated in CDU? The various components of crude oil have different sizes, weights and boiling temperatures. Crude Distillation Unit is used to strip this crude into various products using the difference in their boiling points.Therefore for distillation to take pla ce the temperature of the Crude has to be lordly to around 354 oC so that all the fractions of crude oil feces vaporize and get separated. How Temperature of Crude is increased in CDU? The Temperature increase of Crude oil consists of 2 major steps 1. A 3 Stage Heat exchange (called CDU pre-heat train) of crude with product streams at high temperatures using shell & tube type heat exchangers. This step results in crude existence supplied at 246 oC (elevated from ambient) to the next step The atmospheric Furnace. 2. The atmospheric furnace (C-1A) is then used to further elevate the temperature.Modes of heat manoeuver in furnace are both convective and radiative the crude coming out of the furnace has a temperature of around 354 oC and goes to the flash zone of main distillation column (CL-2). Furnace alone is non used because it would to too expensive and Energy consuming. By exchanging heat with products, the pre-heat train is inspection and repair twin purpose The Crude is be ing heated at the same the temperatures of product streams of SRGO, RCO, KERO is brought down which was needed for their storage. This heat would have otherwise been wasted. Our point of discussion in this report is the First step i. e. The Heat exchanger Network which we will now study in detail. Birla Institute of Technology & Science Pilani 333031 15 3. 2 crustal plate & TUBE arouse EXCHANGER The Pre heat train uses shell & tube type heat exchager for heat graft. ? It consist of two main things as its name implies eccentric & tube-shaped structures ? The shell is a walloping vas with a number of tubes in place it. ? The principle of operation Two unruffleds of different temperatures are brought into close contact but they are not mixing with each other. unrivalled fluid runs through the tubes, and another fluid fly the coops over the tubes (through the shell) to transfer heat betwixt the two fluids.The temperature of the two fluids will tend to equalize. The heat is si mply exchanged from one fluid to the other and vice versa. No energy is added or removed. Common types of shell and tube exchangers Birla Institute of Technology & Science Pilani 333031 16 3. 3 PRE-HEAT TRAIN Description Our point of discussion in this report is first step of the 2 stages used for raising the temperature of crude i. e. the Heat exchanger network in which heat transfer occurs between crude and product streams of RCO, SRGO, and Kero 1. This network is also called the CDU pre-heat train.In this process the temperature of the crude is elevated form ambient conditions at which it is supplied from OM to 246oC. The heat needed for this is coming from the product streams which are at high temperatures. Dual purpose is served in this way heating of crude as well as the chilling of product streams (needed for their storage). The pre-heat train is divided into trio sections on the basis of temperature of crude silklike through them 1. COLD section 2. middle section 3. HOT Section Shown below is the flow diagram of the CDU pre heat train (3. 3. 1) Birla Institute of Technology & Science Pilani 333031 17 1.Cold Section (before Desalter) The crude from battery limit is pumped by pumps P-1/1A at about 15. 8 Kg/cm2 through a preheat train where it is heated to a temperature of 130 ? C before unveiling the Desalter (V-101). The following table shows the shell nerve & tube locating streams of all exchanger in this section along with their inlet-outlet temperatures (3. 3. 2)money changer profit home plate thermionic vacuum tube amount of money surface sphere Heat province Temperature shell tube I O I O S-26 Gasoline Crude 300 x 1 2. 11 107 90 40 65 S-29 RCO Crude 171 x 1 0. 47 116 degree Celsius 54 60. 3 S-12A Crude Kero 2 148 x 1 0. 92 60. 3 72. 6 130 82 S-27A/B Crude SRGO 183 x 2 1. 39 72. 5 0. 3 173 85 S-7 Kero 2 Crude 93 x1 1. 48 199 130 90. 3 109 S-11A/B RCO Crude 134 x 3 1. 49 165 cxv 109 122 2. Mid Section (Between Desalter and pre-topping column) The crude from the Desalter is pumped by pump P-21 A/B and divided equally into 2 streams ( pack A & B) for further heating before submission the Pre-topping column. P-21A/B? Train A S-24, S-9A, S-23A/B, S-9B/C, S-22 CL-1 Train B S-4A/B, S-12B, S-25A/B The crude in train A is preheated by hot-streams of SR Gas Oil (in S-24), RCO (in S-9A, S-23A/B), SR Gas Oil (in S-9B/C), RCO (in S-22) to about 236 ? C. While the crude in Birla Institute of Technology & SciencePilani 333031 18 train B is preheated by SR kero circulating Reflux (CR) (in S-4A/B, S-12B) and RCO (in S-25A/B) to about 240 ? C. Desalted crude from both Train A and Train B streams are unite before entering the pre-topping column. Mixed preheat temperature doable is around 238 ? C at which it is fed to pre-topping Column. Below is the table showing heat exchangers of mid section (3. 3. 3) exchanger plate Service thermionic vacuum tube broad(a) playing area Surface Heat barter Temperature oC pulsate resistan ce I S-9A Desalted Crude RCO S-23A/B RCO S-9B/C SRGO S-22 RCO S-4A/B Desalted Crude Desalted Crude RCO S-24 S-12B S-25A/B O I O SRGO 0. 0 122 138 214 173 Desalted Crude Desalted Crude Desalted Crude Desalted Crude Kero CR 149 x 1 0. 61 184 195 138 152 148 x 2 1. 93 241 184 153 195 82 x 2 0. 54 272 214 195 218 149 x 1 0. 91 320 296 218 236 148 x 2 1. 67 122 161 190 164 Kero CR 148 x 2 1. 8 161 198 216 190 Desalted Crude 113. 15 x 2 2. 0 297 283 228 223 3. Hot Section (At CL-1 Bottom) The top crude from CL-1 bottoms is pumped by pumps P-2/2A to exchangers S16/S-9D in series, where it is heated by SR Gas Oil Circulatory ebbing. It then passes to exchanger number S-11C and further to S-21 where it is heated by Reduced Crude Oil (RCO) to about 246?C. At this Temperature pre topped crude enters Atmospheric furnace (C-1A). The table on next page gives details about every heat exchanger in this section (3. 3. 4). Birla Institute of Technology & Science Pilani 333031 19 Exchanger Service pose bring area Surface Heat Duty Tube Temperature oC collection plate Tube I S-16/9D SRGO CR S-21 RCO S-11C RCO Skimmed crude Skimmed crude Skimmed crude O I O 186 x 2 2. 16 291 250 197 257 175 x 1 0. 61 336 320 239 246 134 x 3 1. 49 336 320 239 246 Birla Institute of Technology & Science Pilani 333031 20 HEAT EXCHANGER PERFORMANCE CALCULATION Birla Institute of Technology & SciencePilani 333031 21 4. 1 critical HEAT EXCHANGER The critical heat exchangers are identified as the ones whose surgical procedure has a major impact on heat exchange rate, Production rate, product quality or environmental and wellness issues. Problem or inefficiency in any of the critical exchanger has a ascetical effect on overall heat exchange process occurring in the crude distillation unit. The engineers need to see that these exchangers are working efficiently for smooth track of the process (Though efficiency monitoring is important for every exchanger but the most attention has to be paid for Critical heat exchangers).Criteria for Classification 1. Fouling is accumulation of undesirable material of heat exchanger surface is called fouling. Fouling is inevitable in heat exchanger but certain heat exchangers are more prone to fouling than others. These exchangers foul in short intervals and need to be cleaned frequently. Their veritable(a) maintenance is very necessary for the heat exchange process. E. g. is S-11/C in hot section is prone to frequent fouling. 2. Large surface area Some heat exchanger have a very large heat transfer area which means they have a large contribution in add up heat exchange taking place.Their inefficiency or by-passing them would have a vital effect of final crude temperature. For example S-23 A/B in the mid section of heat exchanger trains. 3. Single heat exchanger in line If a heat exchanger is single heat exchanger in the line like the one used in circulating reflux then it cannot be stopped or by-passed. For any maintenance work on them t he whole unit has to shut down. Example is S16/9D. In next section the basic act measurement calculations like heat, Duty, LMTD, Heat transfer coefficient is done for some of these critical heat exchangers. Birla Institute of Technology & SciencePilani 333031 22 4. 2 PERFORMANCE ANALYSIS Examples This section analyzes the performances of some main heat exchangers of pre-heat train through calculation of simple performance measurement tools like Heat duty, LMTD & Heat transfer coefficient. The definitions & formulas for these tools can be found in glossary at the end of the report. 1) S-25 A/B ? Type demolish & tube ? Section Mid ? Properties Exchanger no. S-25A/B Service Shell No. of passes Shell Tube Tube RCO Desalted Crude 1 2 full Surface area Heat Sq. M x no. of Duty element 113. 15 x 2 2. 0 (4. 2. 1) ? Design Data Shell 54554 55454 296 241 (I) (O) 49. (uncorrected) Total flow (Kg/h) Operating temperature (? C) LMTD (? C) Tube 77586 77586 197. 7 240. 5 (I) (O) 47. 1 (correcte d) (4. 2. 2) ? Practical data Mass flow rate (RCO) = 59187. 5 Kg/hr S-25A/B Service Temperature, C Shell Tube game M Shell side I 297. 5 O 283. 7 Tube side I O 231. 9 245 Nov 11 Exchanger No. 263 253 198 RCO crude 203 (4. 2. 3) ? Calculations 1. Heat Duty (design) M*Cp*(Ti To) = 2002813. 7 Kcal/hr Birla Institute of Technology & Science Pilani 333031 23 2. Heat Duty (practical) 559336 Kcal/hr 3. Correction factor for LMTD (practical) 1. 01 4. LMTD (practical) 52. 12 (uncorrected), 51. 7(corrected) ? card The practical heat transfer of 559336 Kcal/hr is much lower than the design heat duty of 2002813. 7 Kcal/hr. ? Conclusions 1. The exchanger is not working efficiently 2. out-of-pocket to fouling the temperature difference across the crude side is low which is reducing the total heat exchange in the exchanger. Birla Institute of Technology & Science Pilani 333031 24 2) S-11/C ? Type Shell & tube ? Section Hot ? Properties Its a critical heat exchanger because of the frequent fouli ng Service Exchanger no. Shell Tube S-11C RCO PreDesalter No. of passes Shell Tube 1 2 Total Surface area Sq. m x no. of lement 134 x 3 Heat Duty 1. 49 (4. 2. 4) ? Design data Shell Tube Total flow (Kg/h) 54554 55454 155171 Operating temperature (? C) 336 (I) 320 (O) 239 (I) LMTD (? C) _ 1551 71 246 (O) _ (4. 2. 5) ? Practical data Mass flow rate 59871. 5 Exchanger No. S-11C Service Shell Tube RCO Skimmed Crude pip M Nov 11 Temperature, C Shell side Tube side I O I O 327 315 257. 8 263 330. 2 275 231 255 (4. 2. 6) Birla Institute of Technology & Science Pilani 333031 25 ? Calculations 1. Heat Duty (design) M*Cp*(Ti To) = 6295320 Kcal/hr 2. Heat Duty (practical) 597382. 7 Kcal/hr 3. Correction factor for LMTD(practical) = 0. 75 4. LMTD (practical) 82. 84 (uncorrected), 80. 79(corrected) ? Observations Heat transfer at present is 597382. 7 Kcal/hr which is tolerable as compared to design heat transfer of 6295320. ? Conclusions The present performance of the heat exchanger is satisfa ctory as compared to design. This little mutation in the design heat duty and practical heat duty is imputable to variation in value of Cp of RCO with temperature. Birla Institute of Technology & Science Pilani 333031 26 3) S-23A/B ? Type Shell & Tube ? Section Mid (Train A) ? Properties It is an critical heat exchager becase of its large heat transfer areaService Total Surface area No. of passes Shell Tube Shell Tube (Sq. m x no. of element) RCO Desalted Crude 1 2 148 x 2 Heat Duty 1. 93 (4. 2. 7) ? Design Data Property Shell Tube Total Flow (Kg/h) Temperature (? C) I 54554 241. 0 O 54554 184. 0 I 77585 152. 70 O 77585 195. 0 Specific Heat (Kcal/kg-? C) 0. 646 0. 597 0. 566 0. 617 LMTD (? C) 38. 21 35. 6 (4. 2. 8) ? Practical data Mass flow rate (RCO) = 59187. 5 Kg/hr Temperature C Service Shell RCO Tube crude Shell side beam M Nov 11 Tube side I 260. 2 O 230 I 145. 7 O 178. 8 253 230 142 one hundred sixty (4. 2. 9) Birla Institute of Technology & Science Pilani 333031 27 Calcu lations 1. Heat Duty (design) M*Cp*(Ti To) = 1932602. 7 Kcal/hr 2. Heat Duty (practical) 1161000. 7 Kcal/hr 3. Correction factor 4. LMTD (practical) (uncorrected), (corrected) ? Observations The practical heat transfer of 1161000. 7 Kcal/hr is much lower than the design heat duty of 1932602. 7. The value of LMTD on the other hand is actually higher in case of practical situation ? Conclusions The heat exchanger is not working efficiently. Due to fouling the temperature difference across the crude side is low which is reducing the total heat exchange in the exchanger even after having a high LMTD value.Birla Institute of Technology & Science Pilani 333031 28 HEAT desegregation Birla Institute of Technology & Science Pilani 333031 29 4. 1 HEAT integrating Introduction In Todays process industries like Guwahati refinery increasing energy efficiency is of prime importance. With the rising be of input like crude, power the process has to be designed to have uttermost energy recovery so as to reduce the costs. Heat integration is one of the ways to achieve this. 1. MEANING Heat integration is technique for designing a process to minimise energy consumption and maximise heat recovery.Its part of the broader term Process integration which is a holistic approach to process design which emphasizes the unity of the process and considers the interactions between different unit operations from the outset, rather than optimising them separately. 2. NEED FOR HEAT INTEGRATION Heat integration can lead to substantial reduction in the energy requirements of a process thus save costs. Its the answer to following questions ? Are the brisk processes as energy efficient as they should be? ? What changes can be make to increase energy efficiency without incurring any costs? What is the most important utility mix for the process? What investments can be made to increase energy efficiency? ? How to put energy efficiency & other targets like emission reduction, increasing forget capacity into one coherent strategic plan? 3. TOOLS FOR HEAT INTEGRATION ? coerce Analysis The term soupcon technology was introduced by Linnhoff to represent a set of thermodynamics base tools that that guarantee minimum energy levels in design of heat exchanger networks. Pinch Technology provides a systematic methodological analysis for energy saving in processes & total sites. Its prime objective is to provide energy saving by better process heat integration. Here are some of its key featuresBirla Institute of Technology & Science Pilani 333031 30 1. Based on the first and second law of thermodynamics. 2. Pinch analysis is applicable for both new design as well as the render systems. 3. It was developed for crude distillation systems but is now applicable to large number of process industries. 4. In addition to energy conservation Pinch technology provides oecumenical improvements 5. Some famous Pinch softwares are Pinch ExpressTM, Aspen PinchTM & SuperTargetTM ? render an alysis Retrofit analysis is done to in old process processes to see what modifications suggested by pinch analysis are most adapted for the project.It looks into the optimization of the process through energy capital trade off. In oil refining, retrofit designs are far more common than grass root applications. The retrofit targets are preferably achieved by re-using existing equipment more efficiently rather than installing new equipments and incurring new costs. 4. travel IN HEAT INTEGRATION Shown below are the different steps of heat integration (5. 1. 1) Birla Institute of Technology & Science Pilani 333031 31 5. 2 HEAT INTEGRATION IN CDU 1. IMPORTANCE OF HEAT INTEGRATION IN CDU Distillation is the largest single energy consumer in the Refinery.Large section of oil is fatigued in fuelling the CDU itself. It is energy intensive process as the temperature of the crude has to be elevated to a high temperature of 354 oC. This increase in temperature is achieved by exchanging heat in various heat exchangers between crude and streams of RCO, SR Gasoline, Kero 2 etc which are at high temperature. Heat integration focuses on achieving maximum energy recovery from these streams through an optimized HEN so that the crude can be supplied at highest possible temperature to the furnace, thus saving energy.A recent development in distillation technology has shown potential savings of up to 15-40 % through the heat? integrated exchanger network (pre-heat train) & distillation column. 2. HEAT INTEGRATION AT CDU GUWAHTI REFINEY What has been done? 1. The basis of heat integration in heat exchange process is putting process hot streams in thermal contact with process cold streams. We have already seen how product hot streams of RCO, SRGO etc at high temperature are used to exchange heat with the crude oil at low temperature. 2.Designing of an Optimized Heat Exchanger Network in pre-heat train using heat integration tools like pinch analysis & retrofit analysis in July 20 10. This design allows maximum energy heat recovery. What can be done? 1. Using heat integrated distillation columns. HIDC can save energy by recovering excess heat from the rectifying section for usage in the stripping section. Birla Institute of Technology & Science Pilani 333031 32 2. see the interactions of HEN and distillation column and applying combined heat integration for whole unit.