Shell Global SolutionsConfidential Technical Proposal – PPGJ Project : CPP Gundih AGTU This Confidential Technical Proposal for a Sulfinol-M/X‡ Process Acid Gas Removal Unit (AGRU), Molecular Sieve Dehydration and Mercaptan Removal unit (MSU) and a Shell-Paques Process Sulphur Recovery Unit (BSRU) has been prepared based on the an updated information received from PT PT Tripatra Engineering & Construction (herein after refered to as TRIPATRA) on 18th of July 2008 entitled ” SPECIFICATION FOR SHELL GLOBAL COMPANY ”, hereinafter referred to as the Request For Proposal (RFP). This proposal also incorporates inputs from the meetings and discussions held throughout the period of the proposal development. This Proposal provides preliminary AGRU, MSU and SRU design information based on the feed conditions as specified in the RFP. As the project entails a complex gas treating challenges, we believe that the solution provided best meets the project requirements as outlined by Pertamina EP PPGJ project team. This technical proposal is provided under the Secrecy and Restricted Use Agreemet between Shell and TRIPATRA for the purpose of enabling TRIPATRA to consider the Shell Licensed Processes for application in the PPGJ Project. The corresponding commercial offer shall submitted as a separate document from this technical proposal. ‡Sulfinol is a trademark of Shell DISCLAIMER The purpose of this proposal is to assist Customer, as recipient, in deciding whether or not to proceed with discussions with Shell concerning an engagement of Shell for the license and services stated herein. This proposal is not intended to constitute an offer or acceptance or to give rise to any binding obligation unless and until a formal contract is signed by both parties. Nothing contained herein shall constitute otherwise. Until a final contract is signed, either party may close discussions for any reason with no liability to the other. Shell disclaims any and all liability for representations or warranties, express or implied, contained in the proposal or in any other written or oral communications with Customer concerning this subject matter. Only those particular representations and warranties which may be made in a written contract shall, subject to such limitations and restrictions as may be specified in the contract, have any legal effect. This proposal is confidential and subject to the terms of the Confidentiality Agreement between the parties dated as of 31st July 2008. This Proposal is being delivered for informational purposes only and upon the express understanding that it will be used only for the purposes set forth above. 3 Confidential Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Document History Date 20/9/2008 Issue A Reason Change Issued for internal appoval for Auhors Blas, Wilfredo Koh, Boon Eng Srivathsan, Bharath Bajpai, Vishrut Reviewed/Verified by de Oude, Matthijs Sakthivel, Ramachandran Srinivasan, Rajiv van Heeringen, Gijs Paques B.V. Approved by Van Hooijdonk, Jeroen 4 Confidential COS. The MSU also dries the gas to sales specification. Additional offgas feed stream from the upstream processing units in the CPP are routed to the thermal oxidizer of the BSRU for disposal. Fuel Gas is partially taken from the sales gas to provide the requirements of the CPP.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Block Flow Diagram of Acid Gas Treating Unit (AGTU) The general process line-up for the Acid Gas Treating Unit for the CPP Gundih Station is as follows (only main process streams shown): Sales Gas from AGTU HP Fuel Gas to Distribution MOLECULAR SIEVE UNIT (MSU) Water Make-Up Incinerator Gases Feed Gas to AGTU ACID GAS REMOVAL UNIT (AGRU) LP Separator. H2S. The sulphur species in the acid gas stream out of the AGRU are then recovered in the Biological Sulphur Removal Unit (BSRU) and the desulphurized CO2 stream is then routed to the incinerator. Condensate Stabiliser and Produced Water Injection Unit Offgas Streams BIOLOGICAL SULFUR RECOVERY UNIT (BSRU) Bleed Stream to Effluent Treatment Plant Recovered Sulfur By EPC Contractor By SHELL By SHELL By EPC Contractor Figure I: Acid Gas Treating Unit up Simplified Block Flow Diagram (CPP Gundih) Most of the contaminants (CO2. and Mercaptans) in the Feed Gas to the AGTU are removed by the Acid Gas Remval Unit (AGRU) with the remainder of mercaptans recovered in the Molecular Sieve Unit (MSU). 5 Confidential . 1 2.4 Heat & Material Balance 3.6 Integration with the Molecular Sieve Regeneration Gas Recovery 13 2.4.4.X Process 3.2 Mercaptan Speciation & Handling Feed Gas Condition 2. Background Information Background Information 1.1 1.2 2.8 2. Overview of the Project Scope of Proposal 4 5 6 8 8 8 8 9 9 11 12 12 12 12 The Integrated Treating Line-up 2.5 Use of Solvent Flash Vessel AGRU Feed Gas and Treated Gas Knock Out Drums 12 13 2.1 3.4.4. Use of a Mechanical Refrigeration Loop in the MSU Mercaptans Conversion in the BSRU Heat Integration Opportunities Re-use of Water Streams 13 14 14 14 15 15 15 16 16 16 16 6 The Sulfinol .3 AGTU Plant Capacity 2.5 Equipment 3.2 Product Specifications 2. 1.6 Utility.7 2.4.3 Process Overview Process Description AGRU Process Flow Diagram 3.2 3.4.10 3. Catalyst & Chemical Requirements Confidential .4 Design Considerations & Assumptions 2.9 2.4.3 Use of Shell Proprietary Contacting Internals in the AGRU Absorber 12 2.4.4.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Table of Contents Document History Block Flow Diagram of Acid Gas Treating Unit (AGTU) Table of Contents 1.1 Feed Gas Specifications 2.4 2.4. 5 Heat & Material Balance 4.3 MSU Process Flow Diagram 5.4 Heat & Material Balance 5.2 Process Chemistry 4.8 Utility.2 Process Description 5.7 Stream Summary 4. The Shell-Paques Process – Biological Sulfur Recovery Process 4.6 Utility.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 4.3 Process Description 4.5 Equipment 25 5.1 Process Overview 4.6 Equipment 4.4 BSRU Process Flow Diagram 4. Catalyst & Chemical Requirements 17 17 19 19 20 20 20 20 21 22 22 24 25 25 25 5.1 Process Overview 5. The Molecur Sieve Process 5. Catalyst & Chemical Requirements 7 Confidential . utilities).4. To meet the sales gas specifications. 1. 1. PT Pertamina EP plans to construct and operate a Central Processing Plant (CPP) which will comprise of flowlines. mercaptans.g. Central Java. acid gas treating unit. inlet manifolds. Indonesia.1 Background Information Overview of the Project PT Pertamina E&P intends to produce the gas wells in various fields in the Gundih Area located in Kabupaten Blora.2 Scope of Proposal Shell Global Solutions has been asked to provide a confidential technical proposal for the processes required for the Acid Gas Treating Unit for CPP. The sales gas is to be used for power generation. gas separation units. the process design of the AGTU shall be developed by approved licensor. which includes the following units: • Acid Gas Removal Unit (AGRU) • Molecular Sieve Unit (MSU) • Biological Sulphur Recovery Unit (BSRU) • Caustic Unit* Some equipment items within the AGTU have been excluded from Shell scope in clarification with TRIPATRA and these include: Unit AGRU MSU Equipment Items Filter coalescer. condensate handling unit. F-0301 A/B on feed to MSU Remarks As specified by TRIPATRA As specified by TRIPATRA *Refer to Section 2. The gas is characterized as “difficult” due to the high levels and the prescence of the various impurities in the gas (CO2. 8 Confidential .Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 1.6 with respect to the recommeded removal of the caustic unit from the AGTU. F-0205 on feed to AGRU Filter coalescer. TRIPATRA is participating in the tender of the PPGJ Project for the development of the Central Processing Plant and as required by Pertamina. H2S and COS) as further described in Section 2 of this proposal. produced water injection unit and other required supporting systems (e. 04 0.08 0. 9 Confidential . The following tables outline the composition given for each of the streams. The Integrated Treating Line-up The AGTU integrated design is based on the feed gas conditions and product specifications as outlined in the RFP and as described further below.23 0. H2S.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 2.08 0.8 0.06 0. The following table outlines the composition given: Table 1: Feed Gas to AGTU Flow rate Temperature Pressure Carbon Dioxide Nitrogen Oxygen Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane n-Heptane n-Octane n-Nonane n-Decane H2S Mercaptans Carbonyl Sulphide Feed Gas Conditions 75 MMSCFD 108 400 ºF psig Composition (dry basis) %-mole 23.09 0.17 0. RSH and COS have been taken with a +/.10% variance as advised by TRIPATRA (2) Feed Gas compositions have been normalized with water exception of water content (3) Mercaptan speciation was taken as 100% methyl mercaptan Offgases from the LP Separator and Condensate Stabiliser are combined and with the offgas from the Produced Water Injection Unit are routed to the BSRU.19 0.01 0 7000 1700 50 %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole ppmv ppmv ppmv Notes: (1) Contaminant levels of CO2.47 0. 2. F-0102 A/B.78 2.1 Feed Gas Specifications The main feed gas stream to the AGTU comes from the from the Filter Coalescer.00 0.00 70. 074 0.215 0.4 0 0 100.00800 0.007 45 13 0.00 Notes: (1) Feed Gas compositions have been normalized with water exception of water content.74200 1.096 0.68500 0.600 90.240 0.04800 0.66000 0.17000 0.00000 137 39 0 100.14300 0.099 0.33700 3.01 0.00 0.841 1. (2) Mercaptan speciation was taken as 100% methyl mercaptan.390 32.045 120 40 127 91 MMSCFD ºF psig %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole %-mole ppmv ppmv ppmv %-mole %-mole Composition (dry basis) 4.017 0.037 0.37300 0.12600 0.19700 0.15100 0.286 2.00000 57.41800 0. 10 Confidential .100 0.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Table 2: Off Gas Feed to BSRU Flow rate Temperature Pressure CO2 Nitrogen Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane n-Heptane n-Octane n-Nonane H2S M-Mercaptan COS H2O Condensate Total Feed Gas Conditions 0. max. max. min Water content. Color Flake Size Odour Value 99. max. H2S . out of the Shell Paques Unit has proven use in the agricultural industry and will result in savings on investment of the sulphur workup section. Total sulphur.05 10 1 Bright Yellow 10-15 Odourless cm Unit %wt %wt %wt ppmwt %wt Notes: (1) The biosulphur product. The sulphur work-up section (melter and flaking system) is not a Shell licensed process and thus performance guarantees shall have to be made with the respective vendors. size CO2 content . max. (2) 11 Confidential . max.5 0. max. max. min. H2S Content.2 Product Specifications The AGTU has a total of 3 final products and 3 intermediate products as described below. Carbon Content. Table 3: List of Product Streams from AGTU Stream Sales Gas Recovered Sulfur Incinerator Stack Gas Stream Flash Gas Fuel Gas Bleed Stream Final Products Unit From MSU BSRU BSRU Intemediate Products Unit From AGRU MSU BSRU To Custody Transfer Metering Site Storage Environment To Fuel Gas System Fuel Gas System Effluent Treatment Plant The following product specifications have been applied: Table 4: Sales Gas Specification Parameter Temperature. Value 120 330 7 5-10 5 3 30 Unit oF psig lbs/MMscf micron %-mole ppmv ppmv Table 5: Recovered Sulphur Specification Parameter Sulfur Purity.05 0. max Pressure. Water Content.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 2. max Particles. Inorganic Ash. e.4.4. 2.4 Design Considerations & Assumptions Reference is made to the Block Diagram of the AGTU.4. has been applied.4. For this reason. the amount of mercaptan removal to be performed by the MSU is too high and will result in a bed size which is beyond the practical limitations of Molecular Sieves technology. ‡Calming Section. ADIP-X and Sulfinol are trademarks of Shell 2. SO2 Value 2600 Unit mg/Nm3 Notes: (1) (2) Based on 25oC and 1 atm. In discussion with TRIPATRA the speciation adopted for the feed gas was advised as 100% methyl-mercaptan.3 Use of Shell Proprietary Contacting Internals in the AGRU Absorber The RFP mentions the use of a packed column for the AGRU absorber. 2. The amount of mercapatans in the feed gas to the AGTU is high and on the basis that mercapatans removal in the AGRU is to be achieved using an enhanced MDEA process (i.4 Use of Solvent Flash Vessel Though the amount of hydrocarbon entrainment can be minimized through the use of special internals at the bottom of the main absorber. the use of a solvent flash vessel was reviewed and retained for the following reasons: 12 Confidential . Shell’s ADIP-X‡). 2. such that bulk of the mercaptans (~97%) can be removed in the AGRU and sent for Sulphur recovery.3 AGTU Plant Capacity The AGTU has been sized for a maximum capacity of 75 MMSCFD of the Feed Gas to the AGRU. 2. the following assumptions have been made for the feed gas to the AGRU: • • • It is free of any solid particles It is free of liquid hydrocarbons The gas is at its (water) dewpoint 2.2 Feed Gas Condition For the purpose of the current design.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Table 6: Incincerator Stack Gas Specification Parameter Sulfur Dioxide. Maximum O2 content of stack gas is 3% vol. the use of an MDEA hybrid solvent – Shell’s Sulfinol-X‡.1 Mercaptan Speciation & Handling The mercaptan speciation plays an important role in determining how the desired total sulphur specification can be achieved out of the AGTU. Hi-Fi. Appendix VIII contains a reference list of Sulfinol applications wherein similar combination of contaminants have been addressed. however upon comparison the use of Shell Proprietary Calming Section‡/Hi-Fi‡ trays in the AGRU absorber is expected to reduced the column height by about 2-4 meters as use of packing will require additional space internal liquid redistributors. No further overcapacity has been incorporated at this stage of the project. 13 Confidential . Hence it is recommended to use an Amine Scrubber to recover the MSU Regen Gas. • Presence of about 5 % CO2 in the regen gas will lead to very high consumption / loss of caustic. • 1 less unit to operate as the amine scrubber can be treated as part of the AGRU and does not require a different skill/competence to operate.6 Integration with the Molecular Sieve Regeneration Gas Recovery The option of the proposed Caustic Unit for the recovery of the MSU Regen Gas was compared to the use of an amine scrubber as an alternative option.4. The following are the key benefits seen in the design of the Molecular Sieve Unit if designed on the basis of an inlet temperature of 21oC as compared to a design at a high inlet temperature (about 46oC): • • • The height of the water removal mol-sieves is halved Around 5% decrease in the height of Sulphur removal mol-sieves. • Less regret cost should there be a lower mercaptan content during actual operating conditions. • 1 less toxic waste stream (Di-Sulphide Oil. The design of the filter coalescer is the responsibility of TRIPATRA. which could lead to corrosion. Hence it can be considered to remove the assocaited AGRU Feed and Treated Gas Knock Out Drums under the conditions that: • The filter coalescer is located inside the AGRU plot or such that omission of the AGRU Sweet/Treated Gas Knock Out Drum does not create a portion of piping that can have condensation of free liquids.5 AGRU Feed Gas and Treated Gas Knock Out Drums TRIPATRA has confirmed the inclusion of a filter colaescer vessel in the following locations: 1) 2) upstream the AGRU Feed Gas Knock out Drum downstream the AGRU Treated Gas Knock Out Drum which are expected to perform the same if not better removal efficiency of liquids from the gas stream.4. which will be available for use as fuel gas.7 Use of a Mechanical Refrigeration Loop in the MSU The RFP specifies the use of an Air Cooled Exchanger to cool and AGRU Sweet/Treated Gas stream prior to entering the Sweet/Treated Gas Knock Out Drum. 2.4. The initial conclusion from a +/. This is not an issue with an amine scrubber because the used up amine is completely regenerated. 2. About 17% decrease in the mol-sieve vessel diameter. which is much above the typical inlet temperature to a mol sieve unit based on LNG applcations. 2. (b) A Flash Gas Absorber (FGA) has been included to produce a desulfurized flash gas stream.35% FOB cost comparison of main equipment items was that there is no significant difference but the main benefits of employing an amine absorber for regen gas treating in the MSU are: • Lower plot space requirements due to lower equipment count as well as associated auxillary and caustic storage facilities which will impact the overall installed cost. This will bring the gas temperature down to approximately 116oF (46oC). DSO) to store/dispose.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU (a) The solvent flash vessel provides a buffer/surge capacity which contributes to the operational stability of the system as it protects the regeneration section of the AGRU from being directly affected by any upset in the absorber. It is typically not recommended to design a MSU unit a high inlet temperature. The estimated duty requirement is approximately 1. The effect on the regen gas flow is crucial as this also affects the sizing of the Regen Gas Scrubber and the associated solvent circulation rate and thus the final sizing of the AGRU.4. Further benefit of the refrigeration system can be utilized by cooling the main sour gas feed to the AGTU. This is further described in Section 4 and is based on existing and well proven process technologies. it is required to include a feed pre-treatment unit as part of the BSRU to enable mercaptan conversion into H2S. Propane can be used as the refrigerant for this purpose. This can be further explored and developed in the BDP/FEED stage of the project. 2.10 Re-use of Water Streams At several points of the process free water is knocked out of the system and can be considered for re-use in the system as water make-up. for consideration by TRIPATRA to be able to quantify the benefits of heat integration opportunities and its effect to the rest of the plant that is outside the Shell scope of licensed processes (e.9 Heat Integration Opportunities Heating and Cooling duties have been specified in Appendix III – Equipment Summary Sheets.4. 2.g. which can cause foaming in the amine system. 2.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU • Regen gas flow decreases by about 50%.8 Mercaptans Conversion in the BSRU With most of the mercaptans removed in the AGRU and sent to the BSRU in the acid gas stream exiting the AGRU regenerator column.5 MW and is recommended to be included as part of the utilities system.4. This can be further explored and developed in the BDP/FEED stage of the project. 14 Confidential . which will subsequently improve the sizing of the AGTU. The main considerations will be the presence of hydrocarbons in the water stream. Hot Oil System). 25 wt% Sulfolane. 15 Confidential . which are insoluble in the rich solvent. 3. which is treated with a small slip-stream of lean solvent in the flash gas absorber column (C-1003) positioned on top of V-1003 to reduce the H2S and organic sulfur content. The solvent from the MSU Regan Gas Absorber is added downstream the Flash Vessel to minimize the effects of the amount of mercaptans going to the flash gas stream and thus the corresponding height of the Flash Gas Absorber. which can increase the potential for foaming in the AGRU and operational difficulties in the downstream SRU. The Sulfinol Process AGRU solvent utilizes a non-proprietary formulation of amine. and organic sulfur compounds such as mercaptans. The treated flash gas is routed to the plant fuel gas system. pipeline corrosion inhibitors. Oxygen should also be excluded from the natural gas feed to the AGRU to minimize the potential for oxidative degradation of the solvent.2 Process Description The Sulfinol Process AGRU description and equipment tag numbers referenced below correspond to the Process Flow Diagram in Appendix 1 The natural gas feed first passes through a knockout vessel V-1001 to prevent gas gathering system contaminants such as well treating chemicals. V-1002 before the gas is sent to the MSU. which is supplied under flow and temperature control. Sulfolane and water. are skimmed from the upper layer of the liquid phase in V-1003. etc. The regenerator operates at low pressure and high temperature.3. COS.4. H2S. The molecular structure of Sulfolane is shown below. Dissolved and entrained hydrocarbons are separated from the rich solvent in the flash vessel. The Sulfinol . The feed gas is then contacted counter-currently in the absorber (C-1001) over Shell proprietary Calming Section/Hi-Fi trays with lean solvent. The bottom section of the regenerator column holds some volume which can be used as the system's buffer storage and surge facility by allowing the liquid level to float freely.X Process 3. from entering the gas absorber C-1001. The treated gas is then cooled by the treated gas cooler E-1005 to 21oC and free liquids are knocked out in the filter coalescer. The pre-heated rich solvent is stripped counter-currently in the regenerator column over a medium of trays with steam generated in the reboiler. The reboiler is heated by a hot oil loop. an overhead condenser E-1003.1 Process Overview The Shell Sulfinol Process is a regenerative amine-based solvent technology for the removal of CO2.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 3. The lighter hydrocarbons form flash gas. These contaminants can accumulate in the amine system and potentially lead to operating problems such as foaming and fouling. 1-dioxide) The presence of Sulfolane in the solvent enables the Sulfinol Process to achieve highly efficient absorption and removal of organic sulfur compounds such as mercaptans and COS from natural gas feed. The solvent regeneration system consists of a regenerator column C-1002 with a water wash section. in which the pressure is reduced. and a reboiler E-1004.5-tetrahydrothiopene-1. and CS2 from natural gas feed streams. and 25 wt% water. The Sulfinol Process AGRU design for the PPGJ Project is based on application of a solvent formulation containing 50 wt% amine (43%wt MDEA with 7% wt Piperazine). Entrained heavier hydrocarbons. Rich solvent leaves the absorber column under level control and is routed to a rich solvent flash vessel V1003. CH2 CH2 S O O CH2 CH2 Sulfolane (2. compressor oils and pipeline scale. The lean solvent feed temperature to C-1001 is maintained at 5 °C higher than the feed gas temperature to avoid condensation of hydrocarbons in the absorber. 5 Equipment Equipment Summary Sheets with preliminary sizing of the main equipment items shown above are in Appendix III 3. The condensed water is collected in the reflux/acid gas separator vessel V-1004 and pumped by P-1003 back to the top of the regenerator column under level control.6 Utility.4 Heat & Material Balance Refer to Appendix II 3. CO2. The acid gas from V-1004 is routed to the SRU under pressure control.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Regenerated lean solvent leaves the bottom of the regenerator column and is pumped by the solvent booster pump P-1002 through the lean/rich solvent heat exchanger E-1002 and the lean solvent cooler E1001. 3. A 10% slip-stream of the circulating lean solvent is routed through a mechanical filter and an activated carbon filter. Electricity – for motor drives of air cooler and any associated pumps. The activated carbon filter removes non-ionic surface-active contaminants from the lean solvent. H2S. is cooled in the regenerator overhead condenser E-1003 to condense and recover water. Nitrogen – for Solvent storage & drain vessel blanketting.5 Intermittent use 16 Confidential . COS and mercaptans. The mechanical filter removes suspended solids and particulates from the lean solvent. Table 7 Operating & Equipment Parameters Utility Electricity Heating Duty Water Make-up Nitrogen Unit kW MW tpd Consumption 1150 26358 22. The solvent charge pump P-1001 further increases the lean solvent stream pressure prior to being fed to the top of the absorber The overhead vapour stream from the regenerator column. There is a net loss of water in the AGRU and to maintain the appropriate solvent concentration. which are a potential source of foaming in the AGRU. makeup water (demineralized quality) is added to the system. The estimated utility consumption is shown in Table 7.3 AGRU Process Flow Diagram Refer to Appendix I 3. The activated carbon filter is followed by a mechanical post-filter to prevent breakthrough of carbon fines from the activated carbon filter into the AGRU. which can also promote foaming in the system. Catalyst & Chemical Requirements The following utilities are required for the AGRU Demin Water – Requried as water make-up for losses in the system. which contains water. 17 Confidential . • Recovered sulfur is hydrophilic and directly usable for fertilizer/agriculture applications. A simplified Shell-Paques Process block flow diagram is shown below. These are autotrophic organisms.1 Process Overview The Shell-Paques Process is an environmentally friendly biological process for H2S removal and recovery as elemental sulfur (S) from sour gas streams.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 4. These organisms are naturally occurring and are not genetically manipulated nor modified. • Wide and flexible operating range with short system start-up and shut down times. Regeneration of the scrubbing solution. Sour feed gas enters the bottom of a packed absorber column. is a key feature of the ShellPaques Process. The treated gas passes through a demister to minimize entrainment of solvent and exits the absorber. • Low operating and chemical costs. H2S is removed from the sour gas in the absorber by the alkaline Shell-Paques solvent. The Shell-Paques Process – Biological Sulfur Recovery Process The significant advantages of utilizing Shell-Paques technology in this project include: • A lower CAPEX compared to a Claus-based solution • Ability to handle high levels of CO2 produced in the acid gas from the AGRU • System operates at a lower pressure 4. The energy needed for growth is obtained from the sulphide oxidation process. • Inherently safe operation The Shell-Paques process can be applied to sour feed gases with H2S concentrations ranging from 50 ppmv to 100 vol%. The Thiobacilli catalyst is fast growing and highly resistant to varying process conditions. • Environmentally friendly process based on a naturally occurring Thiobacilli biocatalyst. The Shell-Paques Process has the following performance features: • Achieves essentially complete H2S removal and recovery as elemental S. which means that CO2 is required as their sole carbon source. Regeneration of the scrubbing solution is possible because the caustic consumption due to the absorption of H2S is compensated by the oxidation of H2S to elemental sulfur and hydroxide. The most unique aspect of the process is that it utilizes a living biocatalyst to oxidize H2S to elemental S. rather than its disposal. The biocatalyst belongs to the group of naturally occurring colourless sulfur oxidizing organisms known as Thiobacilli. • Simple process configuration and control with stable operation. The acid gas is first heated to ~350°C with fuel gas prior entering the reactor. A portion of the bioreactor contents is recycled over the settler to maintain the desired dry solid content in the system. of three integrated process sections: an absorber. The biologically produced elemental S actually increases the operational reliability of the system and enhances the H2S absorption. The air supply to the bioreactor must be controlled to minimize the formation of sulfate. The elemental sulfur typically has a purity of ~95-98% on dry basis. In the reactor. It is important to note that the elemental S is produced in the bioreactor and not in the absorber. Extensive laboratory and field research has led to the optimisation of the nutrient solution and dosing rate for this process. The sulfur slurry is then sent to the sulfur recovery section. and a sulfur separator and/or recovery unit. with the recovered water recycled back to the process via the bioreactor. The regenerated solvent is recycled from the bioreactor back to the absorber. the H2S rich solvent is routed to the aerobic bioreactor. The pre-treatment unit includes a reduction section to enable conversion of all sulphur compounds present in the feed gas (especially Mercaptans) into hydrogen sulphide. Material Safety Datasheet (MSDS) for the biocatalyst is as attached in Appendix VII Sulfur Recovery The produced elemental S is separated from the solvent in a settler. the Mercaptans are reduced to produce H2S. The nutrient solution is called Nutrimix 34/32 Solution and contains up to 12 different salts. and consequently foam. The nutrients include certain salts for their growth and maintenance. the sour feed gas is contacted counter-currently with the solvent. The conversion of H2S into elemental S is a biological process. plugging problems that frequently occur in conventional caustic or liquid iron based scrubbing systems are minimized in the Shell-Paques Process. The Shell-Paques Process consists. 18 Confidential . where the dissolved sulfides are oxidized into elemental S. To maintain operability of the Shell-Paques unit. Absorber In the absorber. will have an impact on the process performance due to its tendency to foam. a pre-treatment is specified. Mercaptans (especially methyl-mercaptan) are expected to be fully oxidised to dimethyl disulphide (DMDS) in the bioreactor. The recovered water is recycled back to the process via the bioreactor. thereby regenerating caustic soda. The volume of the bioreactor is designed to achieve optimal activity of the biocatalyst. The exhaust air from the reactor can normally be emitted to the atmosphere without further treatment. and the biocatalysts periodically require nutrients to maintain good performance. above a certain concentration.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU The H2S rich solvent from the bottom of the absorber is routed to the bioreactor. The bioreactor is sparged with air to enable the biocatalyst to convert the dissolved sulfide into elemental sulfur (S). The reduction process is exothermic and the gas needs to be cooled to a suitable temperature (35°C) before entering the Shell-Paques Absober. The elemental S slurry is then further processed in a decanter-centrifuge to obtain an S concentration of ~50 – 60 wt%. Appropriate bioreactor internals are used to ensure complete mixing. where it is processed in a sulphur settler and then the decanter and centrifuge. and is automated by a control system. Feed Pre-treatment Unit Mercaptans have been identified as a contaminant that. Bioreactor The aerobic bioreactor contains Thiobacilli microorganisms that oxidize the dissolved sulfides into elemental S. Because of this feature. in principle. A small slipstream of solvent is typically bled from the system to prevent any build-up of salts. DMDS oil will interfere with the sulfur particles. From the absorber bottoms. an aerobic biological reactor. which is sprayed downwards through the column by nozzles. This alkalinity consumption is compensated by the oxidation of H2S to elemental sulfur. As a result of this side-reaction. which proceeds under oxygen controlled conditions according to the following reaction: NaHS + ½O2 → S o + NaOH In the Shell-Paques Process.7 MT/D of sulfur from the acid gas produced by the AGRU unit. The bleed stream. 4. is harmless and can typically be discharged without further treatment. caustic is required to neutralize the sulfuric acid formed. The Shell-Paques Process unit shall be a single train with one absorber. which is maintained at a pH of ~8-9. This is not part of the licensed process and further information is given in Appendix V. Lean scrubbing solution is 19 Confidential . 4. Thermal Oxidizer (TOx)/Incinerator The purpose of the Thermal Oxidizer/Incinerator is to combust the remaining sulphur species from the main processes of the BSRU The treated gas from the Shell Paques absorber and the Bioreactors are sent directly to the TOx. The absorber has liquid and gas distribution devices in the top and bottom and liquid and gas redistribution devices between the packed beds. alkalinity is consumed. where it is combusted along with the offgas streams from units outside the AGTU. which contains sodium salts and some elemental S particles. The gas streams are heated to ~ 850°C in the TOx mixing chamber. depending on local environmental regulations. the primary air to the TOX burner to combust all of the fuel gas and the secondary air to the TOX mixing chamber to ensure that there is sufficient O2 at the outlet (greater than 2 %v) to oxidise all of the sulphur compounds. H2S is removed from the sour gas by the alkaline scrubbing solution in the absorber. sodium thiosulfate. The biocatalyst is highly resistant to varying process conditions. in which the AGRU Acid Gas is treated counter-currently over a three-packed bed configuration.2 Process Chemistry In the Shell-Paques Process absorber. The SO2 off-gas from the TOx is routed to the vent stack. The bioreactor is a CIRCOX-type air-lift loop reactor.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Sulfur Work-Up Section Optional equipment for upgrading of the biosulphur out of the Shell-Paques Unit to create industrial (molten) sulphur quality is added to comply with the requirements of the RFP. which consists of a tall cylindrical reactor containing multiple internal cylinders to create distinct aerated and non-aerated zones. A small part of the dissolved sulfide will be oxidized to sulfate according to the following side-reaction: 2 NaHS + 4O2 → 2 NaHSO 4 ↔ Na 2 SO4 + H 2 SO4 A small amount of thiosulfate is also formed. the Thiobaccilli biocatalyst oxidizes the H2S to elemental sulfur.3 Process Description The Shell-Paques Process SRU was designed to remove and recover ~25. Fuel gas is combusted with air to provide the high temperature required. There are two air lines to the TOX. and other salts. A small bleed stream is typically withdrawn from the system to prevent the build-up of sodium sulfate. The TOx oxidizes all sulphur compounds and hydrogen in the gas at ~850 °C in the presence of a surplus of air to SO2 and CO2. The absorption of H2S proceeds according to the following reaction: H 2 S + NaOH → NaHS + H 2 O In the above reaction. The absorber operates at low pressure so no flash vessel is required upstream of the bioreactor. and tanks are operated at atmospheric pressure. The TPS module in the sulfur settler is a proprietary internal that is supplied by Paques B. A Vent Air Treatment system can be installed if required to remove any residual H2S present in the bioreactor exhaust air (typically < 1-2 ppmv H2S). Table 9 Vapor Stream Compositions Stream Treated Gas H2S Absorber Vent Air Bioreactor H2S.0-9. Sulfur is recovered from the solution by gravitational settling. which produces a sulfur slurry containing ~10 wt% of solids. either the feed rate to the sulfur dewatering unit can be reduced or the runtime can be shortened.01 1. ppmv < 25 <1 H2O.0-9. which operates continuously. The standard sulfur dewatering unit used in this technical estimate is a decanter-centrifuge type. The sulfur settler is a Tilted Plate Settler (TPS) type. 4. When not operating at maximum load. The sulfur dewatering unit is designed to remove the maximum sulfur load in a 24 hr/day runtime. vol% saturated saturated 20 Confidential . The bioreactor.6 Equipment Equipment Summary Sheets with preliminary sizing of the main equipment items shown above are in Appendix III. 4.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU collected in the top of the bioreactor in a degassing module.4 m3/hr °C Pressure bara pH SO2 750 35 40 1. sulfur settler. it has not been included in the scope of this technical estimate.0 m3/hr 5.4 BSRU Process Flow Diagram Refer to Appendix I 4.40 TBD < 2600Nm3/hr NA 8. The liquid overflow from the settler is low in solids content and is collected in the settler effluent tank and recycled to the bioreactor.064 Nm3/hr 1.3 Effluent Treatment Plant Effluent Treatment Plant Sulphur Processing Section Downstream Unit (1) Environment 1656 kg/hr 40 NA 8.5 Heat & Material Balance Refer to Appendix II 4.7 Stream Summary The estimated stream conditions and compositions based on the design conditions (per Shell-Paques Process train) are shown in the following tables: Table 8 Stream Conditions (per train) Temperature Stream Stack Gas from Incinerator Sour Water Bleed Sulfur Cake @ 60 wt% Solids Flow 43.V. which produces a sulfur cake with a dry solids content of ~50-60 wt%. however.3 Notes: (1) To be confirmed during the BDP / FEED design phase.V. The bioreactor internals are proprietary and is supplied by Paques B. the latter typically being the preferred option. (2) Fuel gas is assumed to be supplied from the treated gas ex MSU unit. which is deemed suitable for this service and eliminates the need for an air blower. The water should have a maximum hardness of 10 0DH (= total Ca + Mg < 70 mg/l). HSmg/l <1 < 1 (1) Na+ kg/m3 25-35 25-35 (1) SO42. anions (carbonate. Caustic – Caustic (NaOH) is added to the Shell-Paques Process to provide solvent alkalinity and facilitate H2S absorption. The sulfur product is hydrophilic with a small particle size and can be re-diluted if necessary for easier handling. Catalyst & Chemical Requirements The following utilities and consumables are required for the Shell-Paques Process: Electricity . Caustic is typically added as a 20 or 50 wt% solution. Fuel Gas – Fuel gas is required for both the pre-treatment unit and the incinerator to meet the heating requirement of the process gas. Air – Air is required for sparging the bioreactor. Nutrient Solution .2 648 34. Treated gas from the MSU unit is used as the basis of design and further optimisation of fuel gas consumption can be performed at the next design phase. 4. Nutrimix 34/32 is supplied by Paques B. which makes it very suitable for agricultural purposes. Table 11 Electricity (1) Cooling Duty Caustic (100 wt%) Nutrients-Nutrimix® Make-Up Water Fuel Gas (2) Notes: 34/32 Utility & Consumable Estimates kW MW kg/hr li/hr m3/hr kg/ hr 981. sodium thiosulfate).26 1260 (1) Based on an overall efficiency of 70%.V.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Table 10 Liquid Stream & Sulfur Cake Compositions Stream S° Bleed < 2 g/l Sulfur Cake @ 60 wt% Solids 60 wt% Notes: (1) Aqueous phase composition. evaporation in the absorber and bioreactor.Nutrient solution (Nutrimix 34/32) is required for the maintenance of the Thiobacilli biocatalyst. and to compensate for the loss of sodium ions with the bleed stream.7 11. The estimated price is Euros 1.8 Utility. Plant air is available at 6 barg and ambient temperature. bicarbonate) and small amounts of biocatalyst and sulfur. Drinking quality water quality can typically be used as make-up water. Cooling water is used to cool the rich solution and maintain the bioreactor temperature in an optimum temperature range.3 5.Electricity is required for the pumps and the decanter-centrifuge. catalyst and chemical consumption estimates are shown in Table 14.20/liter. Make-Up Water . The utility. The recovered sulfur is in the form of a wet cake or paste.The biological oxidation of H2S to elemental sulfur is an exothermic reaction. and with the sulfur product. 21 Confidential .Make-up water is added to the Shell-Paques Process to compensate for losses via the bled stream. It should be free of chlorine and have no suspended particular matter.+ S2O32 kg/m3 20-40 20-40 (1) HCO3-+ CO32kg/m3 30-50 30-50 (1) The bleed stream is primarily water containing some salts (sodium sulfate. Cooling Duty . Relevant adsorption and regeneration fundamentals are discussed in greater detail below with respect to dehydration molecular sieves. temperature and pressure have little influence. the saturation zone gets longer and moves downward. 22 Confidential . as presented in Figure V. In normal operating range. the sieve loading in the mass transfer zone progressively drops from saturation level at top to rest loading at bottom. With time. The water removal (4A or 3A) and mercaptan removal (5 A or 13 X ) molecular sieves are used in series to achieve simultaneous dehydration and mercaptan removal in a common vessel. however. A bed is removed from adsorption service and regenerated by passage of hot gas which desorbs and carries away the adsorbed water and mercaptans from the sieves. the length of the mass transfer zone in natural gas dehydration is a function of the molecular sieve grade. In general. Dehydration and mercaptan removal of the process gas is achieved by its passage through one or more fixed molecular sieve bed(s). No water adsorption takes place in the saturation zone. called the Mass Transfer Zone (MTZ). The regenerated bed containing small amounts of water and mercaptans (residual loading) is returned to adsorption service after cooling. In the meantime the process gas dehydration is achieved by another other bed(s). The bed at the top will be saturated with water under the feed conditions of temperature. a non-utlized zone is created. on the other hand. These fundamentals are similar and are equivalently applicable to mercaptan removal molecular sieves as well. A finite part of the bed below the saturation zone is engaged in dehydrating the gas from feed water concentration (wet) to effluent water concentration (dry). This speed is directly related to the rate of water removed from the feed gas.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 5. The adsorption step should be terminated before imminent breakthrough to allow a reliable operation which will meet the required specification. remains constant for the given application. thermal swing regenerative adsorption process is used. The mass transfer zone. The bed below the mass transfer zone is potentially active but takes no part in dehydration. pressure and water concentration and is called the Saturation Zone (SZ). 5. gas superficial velocity and water concentration in feed. Thus the natural gas dehydration and mercaptan removal is continuously accomplished while the beds themselves undergo cyclic batch operations of adsorption and regeneration. The length of the mass transfer zone. Correspondingly. During the course of adsorption two zones will develop. gas flows usually from top to bottom of a regenerated bed.1 The Molecur Sieve Process Process Overview In natural gas dehydration and mercaptan removal applications with type 4A or 3A sieves. In doing so. Adsorption In adsorption. moves down with the same speed as the elongation of the saturation zone. Water stripped off by the hot gas is condensed and disposed of. This counter-current dried gas cooling is adequate in dehydration applications and has an advantage of valving simplicity and "thermal pulse". At the end of heating step and before the bed is returned into service. This can be attributed to bulk desorption of water. Heating gas temperatures of 320°C is required for 4A molecular sieves and is dictated by the thermal stability limitations of these sieves. in process stream Product Spec. it is necessary to cool the bed to restore its adsorption capacity. thus enabling deep regeneration. Non-utilised zone (NZ) Figure V Bed Zones Regeneration The objective of regeneration is to strip off the adsorbed impurities from the bed. b) The m ass transfer or chem ical reaction zone (M TZ/CZ) wherein the adsorbent is only partially loaded and the contam inant level drops from its feed concentration down to the product level. For both the heating and cooling steps the rise and fall of gas temperature (at the start of heating and cooling steps respectively) is controlled to minimise thermal fatigue stresses of the steel. The presence of a plateau (at approx. after it has been taken out of adsorption service. While the shape of the outlet heating gas temperature varies widely from application to application. This is conveniently done by passage of hot gas and then cold gas through the bed. Lower temperatures are impractical from stripping kinetics point of view and may lead to less efficient removal. using a slip stream of the dried product gas supplied counter-currently. based on the low water content specification. The gas outlet temperature is expected to come to within 15 . This is done by continuing the passage of regeneration gas without the supply of heat.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Contaminant conc. Direction of the flow Feed Concentration Saturated Zone (SZ) a) The saturated zone (SZ) wherein the adsorbent has achieved its maximum loading and the concentration of the contaminant in the process stream does not change.20°C of the inlet temperature at the end of heating and cooling steps. in which the initial part of the cooling step also achieves some stripping due to hot cooling outlet gas. 150°C) is sometimes reported. Mass transfer or chemical reaction zone (MTZ/CZ) c) The non-utilised zone (NZ) wherein both concentration and adsorbent loading changes are negligible. The hot regeneration gas serves two important purposes: provide heat to desorb water and act as carrier gas to carry away the desorbed impurities. 23 Confidential . The regeneration is carried out at the normal operating pressure. 0 300. gas flows downwards through the bed.0 150. The recommended adsorbent for dehydration is 4A molecular sieve and the additional bed for mercaptan removal can use either 5A or 13X molecular sieves.0 200. [ hour ] Figure 3 Typical temperature profile for a type 4A mol sieve dehydration unit Water is typically desorbed in the "flat" peak and the peak flow rate is a rule of thumb 3 times the average stripping rate . And mol seive units are generally sized for 3 years lifetime 5. During the adsorption.0 100. It is important to realise that during the initial part of the heating step. Two beds operate in parallel in adsorption mode and one bed operates in regeneration mode. U-1000) leaves at 21 °C and is passed over molecular sieve beds. during the heating and cooling stages. as the temperature climbs up. and cooling modes under control of a sequence control system. Later in the heating step the condensed water is re-vaporised. Each molecular sieve bed can be completely isolated from the process to allow molecular sieve change out during operation. gas flows upwards through the bed.0 0 1 2 3 4 5 cooling stand-by 6 7 8 9 10 11 time from start of regen. Each molecular sieve bed cycles consecutively through adsorption.2 Process Description The treated gas from the Acid Gas Removal Unit (AGRU. removing the remaining mercaptan content and water to meet the sales gas specification.0 0. heating. free water can be formed in the upper section of the bed and on the inside of the top dome of the vessel.0 temperature [ ° C] 250. This is because these parts offer relatively cold surfaces for moisture in regeneration gas to condense. Ageing of Mol sieve The deactivation rate of molecular sieves as a function of number of regenerations. The gas leaving the molecular sieve adsorbers is split into three streams which are: a) as sales gas b) fuel gas supply c) regeneration gas 24 Confidential .0 heating 350.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU 400.0 50. The heated gas stream passes upwards through the molecular sieve bed.6 Utility. Catalyst & Chemical Requirements The following utilities. The desulphurized regen gas passes through the regen gas knockout vessel. Table 12 Operating & Equipment Parameters Utility 4A Adsorbent 5A/13X Adsorbent Heating Duty Electrcity Nitrogen Unit m3 m3 kW kW Consumption 29. catalyst/adsorbent and chemicals are required for the MSU Electricity – for motor drives of air cooler and any associated pumps. V-1302 and is then compressed by a centrifugal compressor K-1301 and routed back to the inlet of the treated gas cooler (E-1005) in the AGRU where it combines with the feed gas. The regeneration-gas flow rate is constant and temperature control of this gas stream is achieved by bypassing E-1302.4 Heat & Material Balance Refer to Appendix II 5. is routed to the regeneration-gas heater (E-1301).5 m3 and does not contain any volume for contingency (e. Condensed water. 5. 5. After passing through the bed in heating mode. which is a Sulfinol-X absorber integrated with the rest of the AGRU. where it is heated and subsequently used for regeneration of the regenerating bed.3 MSU Process Flow Diagram Refer to Appendix I 5.g breakage during shipping) 25 Confidential . which also may contain co-adsorbed hydrocarbons.Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU The regeneration gas. the regeneration gas is cooled by air cooler E-1302. rounded up to the nearest 0.5 Equipment Equipment Summary Sheets with preliminary sizing of the main equipment items shown above are in Appendix III. Nitrogen – for purging Instrument Air – for actuation of the valves Heating Medium – for actuation of the valves The estimated utility consumption is shown in Table 12. The gas leaving V-1301 still contains the mercaptans removed from the adsoprtion beds and is recovered by the regen Regen gas Gas absorberAbsorber. using hot oil. The slipstream is normally heated to 320°C. with a maximum of 350°C in E-1301.5 18. thereby driving the water and mercaptans from the molecular sieves. C1302. is knocked out in vessel V-1301 and routed to water effluent treating/re-injection.5 875 520 Intermittent use Notes: (1) Adsorbent volumes are based on the total requirement for 3 beds. Shell Global Solutions Confidential Technical Proposal – PPGJ Project : CPP Gundih AGTU Appendices The following Appendices are supplied as attachements to this proposal Appendix I Appendix II Appendix III Appendix IV Appendix V Appendix VI Appendix VII Appendix VIII Simplified Process Flow Diagrams Heat & Material Balances Equipment Summary Sheets General Information on Biosulphur Biosulphur Workup Options Sulphur Melter Information Material Safety Data Sheets Reference Lists 26 Confidential .