1. Process Description:

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1 1. Process Description: The coal is converted to Raw Syngas in the Gasification Section. The Raw Syngas produced out of the Gasifier would be shifted (water gas shift) to adjust required H2/CO ratio and would be cleaned to produce pure Syngas (CO+H2+CH4). The treated syngas is used in Methanator to produce SNG, in Methanol Synthesis block to produce Methanol and in FT block to produce FT Diesel/Naphtha. 1.1 Process Route ASU (Air Separation Unit) Coal Preparation Coal Gasification Gas Conditioning and Cleanup SNG Process Methanol Process FT Synthesis/Refining ASU (Air Separation Unit) The Gasification Process of the Plant will use pure oxygen to limit inert gases (argon and nitrogen) in the product syngas. Oxygen is provided to the Gasifiers battery limit by a cryogenic air separation unit (ASU) supplied by a suitable process licensor. To maintain reasonable size and energy consumption of the ASU, oxygen purity of about 99.8 mol% is selected. The ASU also supplies high pressure (HP) and low pressure (LP) gaseous nitrogen for use within the gasification facility. Typically, the nitrogen requirement for the Gasification Island can be easily met by the ASU with no additional capital investment because nitrogen is a by-product from the Facility Coal Drying and Preparation Coal drying unit has been considered to bring down the moisture content of the Indonesian coal contains from 50% to 20% before feeding into the coal preparation Unit. The coal preparation is designed to prepare the coal feed to the required standard for the gasification plant. The coal from the storage area is conveyed to a crusher. The crusher is typically a hammer mill type. Fine grinding of the coal is not required because fines are typically associated with carbon loss in the gasifier. Typical size distribution is 88% between 0.15mm and 6 mm. The milled coal is screened to size and oversize is recycled to the crusher. The sized coal is conveyed to a kiln type dryer that contacts the coal with heated air. A bucket conveyor lifts dried coal to the top of the coal hoppers Gasifier Feed System Page 1 of 13

2 The gasifier feed system consists of weight bins, conveyors, and lock hopper systems that supply the gasifier with coal at pressure. Carbon Dioxide from the Acid Gas Removal system (AGR) is used as transport gas to improve the syngas yield. The coal feed is pressurized in a lock hopper system and metered into the gasifier using a rotary or screw feeder. Steam and Oxygen are injected at the bottom of the gasifier, beneath the grid. Together they provide the energy to fluidize the gasification mixture Coal Gasification Coal gasification is the process of reacting coal with oxygen and steam to form a product gas containing Hydrogen (H2) and Carbon Monoxide (CO). The resulting gas mixture is called Synthesis gas or Syngas and is itself a fuel. Gasification is essentially incomplete combustion. From a processing point of view the main operating difference between Combustion & Gasification is that Gasification consumes heat evolved during combustion. Under the reducing environment of gasification the sulfur in the coal is released as hydrogen sulfide rather than sulfur dioxide and the coal s nitrogen is converted mostly to ammonia rather than nitrogen oxides. These reduced forms of sulfur and nitrogen are easily isolated, captured, and utilized, and thus gasification is a clean coal technology with better environmental performance than coal combustion. The various reactions that take place in the Gasifier are shown in the below: Within the reaction bed, the coal reacts with steam and oxygen. The process accomplishes four important functions; it decakes, devolatilizes, and gasifies the feedstock and if necessary, agglomerates and separates ash from the reacting coal. At the specified operating conditions, coal is gasified rapidly to produce a synthesis gas product consisting of hydrogen, carbon monoxide, water vapor, and methane. Additionally the gas contains small amounts of ammonia, hydrogen sulfide, and other impurities. The syngas exits the top of the gasifier through a refractory lined to the inlet of the primary cyclone. Page 2 of 13

3 1.1.5 Fines Recovery The primary fines recovery and recycle system consists of two cyclones in series, the primary and secondary cyclones. The cyclones collect most of the fines from the gas stream leaving the gasifier. The primary cyclone is refractory lined due to the temperature. Syngas from the primary cyclone enters the secondary cyclone which is similarly refractory lined. The fines collected in the cyclones are returned to the fluidized bed of the gasifier by means of a dip-leg Ash Disposal Coarse ash is removed from the bottom of the gasifier, cooled, and discharged through a lock hopper system. Ash is conveyed by water cooled screw conveyors for further cooling and discharged to an ash storage silo in dry state. Ash from the silo is mixed with water in a pug mill before loading on a truck for disposal Waste Heat Recovery The heat recovery steam generator (HRSG) increases the plant s efficiency by generating steam from the hot syngas leaving the secondary cyclone. The HRSG is a natural circulation boiler which has a single drum and steel structure. The syngas flows sequentially through the steam generator section, the superheater, and the economizer before leaving the bottom of the HRSG. Steam produced by the HRSG is used as feed to the gasifier and produced in excess for use in steam turbines for production of power Syngas Clean-up The cool syngas from heat recovery passes to a third high efficiency cyclone and then to a ceramic/metal filter for further dust removal. The collected fines are recycled to the gasifier through the fines management system. The syngas is then washed in counter current scrubber to remove the residual solids. Evaporation of water in the scrubber cools the gas and concentrates the water so a continuous blow-down is required. After removal of fines from the raw syngas, it goes to Gas Adjustment and Purification Section Fines Handling Dry fines collected from syngas clean-up are routed to a fines silo through a lock hopper system. They are collected in the silo and returned to the gasifier. The system is referred to as the Fines Management System and is included to maximize the carbon conversion. Normally all fines are recycled to the gasifier where they agglomerate and are discharged with coarse ash. Page 3 of 13

4 Sour Water Treatment The blow-down water from the syngas scrubber is saturated with hydrogen sulfide that is produced in the gasifier from sulfur in the coal. The blow-down is stripped in packed column and the overhead gas sent to the sulfur recover unit. The stripped bottoms is cooled and treated by a clarifier to settle the ash. The solids containing underflow is used to wet the dry ash in the pug mill during loading. Clarified overflow is reused in the process after treatment Block Flow Diagram and Mass Balance Gas Adjustment and Cleanup The process units in gas conditioning and purification are: SHIFT CONVERTOR: The purpose of the Shift Converter Unit is to meet the H2: CO ratio 3:1 for SNG Methanator and 2:1 for Methanol and FT Synthesis. The CO will be converted to H2 through reaction with steam at a temperature around 260 ºC. Heat from reaction will be recovered by HRSGs to produce low pressure steam. Before entering the shift unit, the gas will be pre-heated to desired process temperature. Water Gas Shift Reaction: CO + H2O CO2 + H2 ACID GAS REMOVAL UNIT (AGRU): The duty of the AGRU is to remove contaminants (e.g. H2S, CO2, COS, HCN) from the raw sour synthesis gas produced in the coal gasification island to meet the feedstock specification of the downstream Units. Rectisol offers one of the efficient ways of removing Acid gases from syngas. Page 4 of 13

5 RECTISOL: Rectisol uses refrigerated methanol as the solvent for physical absorption of Acid gases & other impurities present in Raw Syngas. Raw Syngas from the Shift Converter Unit, which is at 43 C is cooled down to 7 C by using spiral wound heat exchanger. Syngas containing impurities (trace amount of NH3 & HCN), H2S and CO2 is fed to the Absorber Column. Rectisol unit removes H2S and CO2 in one single absorption process and produces ultra-pure Syngas (total sulfur <0.1 ppm(vol), CO 2 <2 ppm(vol)). ABSORBER COLUMN The Absorber Column has three section namely pre wash section, H2S absorption section and CO2 absorption section. The gas is then fed into the pre wash section of ABSORBER where trace components like NH3 and HCN are absorbed with a small stream of the sub cooled laden methanol coming from H2S Absorber. The gas is then routed via chimney into the H2S absorption section where H2S and COS are scrubbed out with CO2 saturated methanol coming from the CO2 Absorption section. In this section H2S is absorbed at around (-) 26 to (-) 38 C. Desulfurized Syngas then enters the lower part of the CO2 Absorption section. In the CO2 Absorption section the gas is wash with pure methanol (hot regenerated methanol + makeup methanol) at around (-) 44 to (-) 47 0C, pure methanol being fed to the top of the Absorber. Part of the methanol from CO2 absorber is routed to the top of the H2S Absorbing section while the balance flows to the CO2 regenerator where it is flashed at the medium pressure removing CO2. The laden methanol from H2S Absorption section flows to the H2S Regenerator and the recovered H2S will be further treated in the downstream Oxy-Claus Unit to recover elemental Sulfur with purity over 99 %. This elemental sulfur would be sold in the market for various downstream product applications like Sulfuric Acid Plant, Fertilizer industries etc. CO2 and H2S free methanol, from the H2S & CO2 Regenerator, is sent to the hot Regenerator for regeneration to obtain pure methanol. The clean Syngas after Rectisol Unit will be fed into downstream Unit for producing SNG, Methanol and FT Diesel. The Block Flow Diagram of Rectisol Unit is shown in the below: Page 5 of 13

6 SRU (Oxy-Claus Process): The duty of the SRU is to recover sulphur from the H2S recovered in Rectisol (AGRU). The sulphur recovered through Oxy-Claus method is 99% pure SNG Process The Methanation step converts Low BTU Gas (3000 Kcal/Nm 3 ) by the following overall chemical reaction to High BTU (8500 Kcal/Nm 3 ) Gas: A typical schematic Process Diagram below presents process / plant configuration. Methane is synthesized from hydrogen, carbon monoxide and carbon dioxide in the presence of a highly selective nickel based catalyst. The above Methanation Reactions are highly exothermic and heat released is utilised to heat the incoming feed gas as well as for steam generation in waste heat boilers. Hot feed gas, after indirect exchange with the product gas, is passed through a Sulfur Guard Reactor to remove last traces of impurities before entering the Methanation synthesis loop. The synthesis loop consists Page 6 of 13

7 of a Methanator, waste heat boilers and a recycle compressor. Feed gas composition to the Methanator will be set by combining the fresh feed gas stream with the gas stream circulated by the recycle compressor. Reaction heat from the Methanator is removed in the high and low pressure waste heat boilers where HP and MP Steam is generated. Product gas from synthesis loop is cooled in a feed/recycle product heat exchanger and further cooled in a final product cooler to achieve ambient temperature. Condensed water is removed in a product condensate separator. The process condensate is further treated/polished and recycled in the plant as make-up water. The syngas from Gasification following preliminary cleaning and heat recovery by steam generation is divided in two streams. When a post stream (around 2/3rd) is routed to the Water Gas Shift Reactor (Isothermal High Temp Reactor) and the other part is by-passed around the Shift reactor. The above configuration is adopted to adjust H2:CO ratio at 3:1 following CO2 removal at the Acid Gas removal (AGR) unit. The mixed stream ex-water gas shift is routed to AGR in order to remove the Carbon Dioxide and also to remove the condensed water formed at the Water Gas Shift (WGS) reaction section. Generally, the Sweet Syngas after Acid Gas (H2S + CO2) removal is split into (3) streams. The first stream is fed to the 1st Methanation Reactor together with part of the outlet stream from this (1 st ) Reactor. The recycling of the Gas is achieved by using a compressor. Further, the part of the methanated gas (Non Recycled) is further mixed with the 2 nd Fresh Feed Syngas Stream and routed to the Second Methanation reactor. In the similar way, the outlet from the 2 nd Methanation Reactor (part stream) is sent to the third Methanation Reactor along with 3 rd fresh syngas stream. Finally, the exit from the 3 rd Methanation Reactor is sent to the Cooling Section and then to a Carbon Dioxide (CO 2) Removal unit. The SNG produced is further dried. Process Flow Diagram: Page 7 of 13

8 PRODUCT (SNG) GAS COMPRESSION AND DRYING The product SNG from the methanation section is further compressed by steam driven centrifugal compressor from around 60 Bar to around Bar depending upon on the Gas SNG pipeline pressure. Depending on the product SNG Gas condition and composition; the SNG can be subjected for a dehydration step involving Molecular Sieve Adsorption/Drying. This step may be suitably incorporated depending on the overall balance based on specific technology/ licensor SNG PROCESS BLOCK FLOW DIAGRAM METHANOL PROCESS Methanol Synthesis: Methanol is synthesized from hydrogen, carbon monoxide and carbon dioxide in the presence of a highly selective copper based catalyst. The principal synthesis reactions are as follows: These reactions are highly exothermic and the heat of reaction must be promptly removed from its source. This is accomplished most effectively in the two stage methanol synthesis, which consists of a water- cooled and a gas- cooled methanol reactor system. Preheated recycle gas and synthesis gas are mixed and routed to the gas cooled methanol reactor. Passing the tube side, the feed gas is further heated up to the inlet temperature of the water cooled methanol reactors, where the synthesis reactions take place in the catalyst filled tubes. The heat of reaction instantly is removed from the catalyst by partial evaporation of boiler feed water, circulating between the reactor shell and the top mounted steam drum, simultaneously generating steam. The efficient heat removal from the reaction zone permits operation of the plant with a very low recycle gas rate and still processing of high CO yields in the gas. A quasi-isothermal condition is maintained in the system which ensures a high conversion rate, eliminating the danger of Page 8 of 13

9 catalyst overheating and keeping the formation of byproducts at an extremely low level. This results in a very long service time of the methanol catalyst. The relationship at saturation conditions of the steam / water mixture defines the boiling water temperature by pressure control at the steam drum and maintains by this the exact and constant temperature control in the catalyst filled tubes. The medium pressure steam produced will be exported into the steam system of the overall plant, to be used for process, heating or turbine drivers after superheating. Apart from methanol and water vapour produced, the reactor outlet gas contains nonreacted H 2, CO and CO 2, inerts like CH 4 and N 2 and some traces (ppm) of reaction byproducts. This gas needs to be cooled down in order to separate CH 3OH and H 2O. The hot outlet gas partly is used for preheating MP Boiler Feed Water and for preheating the recycled gas. Further on it is cooled down in an air cooler and in the water cooled final cooler. Separation of crude methanol from the two-phase reaction mixture takes place in the methanol separator. The liquid fraction is released to the distillation unit. The gaseous fraction is routed back to the recycle gas compressor to be re-compressed and recycled. A small amount of unreacted gas is purged from the synthesis loop in order to avoid the accumulation of inert gases. The purge gas with a considerable heating value shall be fed into the fuel gas system. Alternatively the purge gas can be used for production of hydrogen in a hydrogen recovery unit. Methanol Synthesis Flow Scheme: METHANOL DISTILLATION: The crude methanol produced in the synthesis unit contains water, dissolved gases and small quantities of undesirable but unavoidable by-products - partly higher and partly lower boiling than methanol. These impurities will be removed in the distillation unit in order to achieve the pure methanol product specification required. Removal of the light ends and remaining dissolved gases is carried out in the pre-run column. Afterwards the methanol is separated from the high boilers in the pure methanol columns. Page 9 of 13

10 Dissolved gases are flashed out by simply expanding the crude methanol from the methanol separator into the low pressure expansion gas vessel. The dissolved gases escape and are released by pressure control into the expansion gas line to the fuel gas system. In case of short-time methanol flow fluctuations, the level in the expansion vessel will be maintained by a level controller. Surplus of crude methanol from this vessel is discharged into the crude methanol tank, while a deficiency could be made up from the same tank. Crude methanol is fed from the expansion vessel to the pre-run column, where the low boiling byproducts are removed. The light ends are taken overhead with a large volume of methanol vapours. The overheads are passed to a condenser and the condensate is pumped back to the column reflux system thereby recovering residual methanol. The pre-run column is heated by re-boilers, using low pressure steam. The bottoms product, stabilized methanol, is fed to the pure methanol columns, first to the pressure pure methanol column. Water and other high ends are removed. Pure methanol is discharged overhead in both columns. The overhead vapours of the pressure column are condensed in the reboiler/condenser and are utilized for re-boiling the bottoms of the atmospheric column. Methanol condensate is collected in the reflux vessels, fed back as reflux to the column top and for the other part further cooled down as product and routed to the pure methanol inter-mediate tanks. The reboiler heat for the pressure column is provided by low pressure steam. The bottoms product of the Pressure Column containing the high ends is fed to the atmospheric pure methanol column. Pure methanol is discharged overhead, condensed in an air cooler and further cooled down. From the reflux vessel the product stream is routed to the pure methanol intermediate tanks and the reflux pumped to the column top. In order to reduce the contamination in the process water at the bottom of the atmospheric column, the installation of a liquid side draw in the lower part of the atmospheric column can be provided. The drawn liquid, mainly containing methanol and high ends, can be vaporized and burnt together with fuel. Low point drainage in the distillation is connected to the slop system. In case of repairs, the relevant equipment can also be emptied into the slop vessel. The methanol from the slop vessel is pumped to the crude methanol tank. Methanol Distillation Flow Scheme: Page 10 of 13

11 METHANOL PROCESS BLOCK FLOW DIAGRAM: FT/REFINING PROCESS: The FT Process operates in the temperature range of C & at a pressure of 30 atmospheres with Cobalt as catalyst in the slurry Bubble Column reactor and produces a liquid product with a high proportion of high molecular weight linear waxes, which maximizes the production of Diesel. In the FT process one mole of CO reacts with almost two moles of H2 to give a hydrocarbon chain extension (-CH2-). The main chemical reaction involved is: nco + 2nH 2 (- CH2 -) n + H 2O The reaction affords mainly aliphatic straight chain hydrocarbons (CxHy), containing a lower fraction of olefins and of oxygenates (organic acids and ketones). The FT chain-growth process is similar to a polymerization process resulting in a normal distribution of chain-lengths of the products, whose spanning carbon numbers are approximately from C2 up to C90. This chemical reaction is highly exothermic. Page 11 of 13

12 The outputs of the FT reactor are Liquid Condensates, Waxes, and FT Tail gas, as well as FT Water. The FT Tail gas is sent to the ATR reformer to produce additional Syngas. A part of the produced Syngas is sent to PSA for producing pure hydrogen which is used in the Hydro cracker unit of Product Up-gradation/Refining section).the remaining Syngas is recycled to the FT inlet. The Liquid Condensates are sent to a Condensate Stabilizer, in order to remove the C4- components (including dissolved CO2) from the Condensates. The Stabilized Condensates are mixed with the Waxes and sent to a Hydro treating Unit, in order to treat the light olefins. The Hydro treated mixture is mixed with a residue recycle from final fractionation, and sent to the Hydrocracking Unit (HDK), where the FT products will be cracked and isomerizes in order to obtain the final products of the CTP Complex. The HDK outlet products are first stripped in order to eliminate the C4- components, and then sent to the Fractionation Section. Naphtha and Diesel final products are recovered from the Main Fractionator and sent to Storage while the Bottom Residue is recycled back to Hydrocracking Unit to add more Naphtha and Diesel. The Block Flow Diagram of Fischer-Tropsch & Product Up-gradation/Refining Section is shown in below: FT AND UPGRADING PROCESS BLOCK FLOW DIAGRAM: Page 12 of 13

13 BLOCK FLOW DIAGRAM OF ALL UNITS Page 13 of 13