FIELD OF THE INVENTION
This invention relates to a process for the production of Urea from high ash coal.
This invention further relates to a process for the production of Urea, a chemical fertilizer from synthesis gas that is generated through bubbling fluidized bed gasification of high ash coal. The invented process contains conversion of high ash coal into synthesis gas in an oxy blown bubbling fluidized bed gasifier, synthesis gas clean-up, water gas shift conversion, acid gas removal, pressure swing adsorption of Hydrogen gas, Ammonia conversion and Urea conversion.
BACKGROUND OF THE INVENTION AND PRIOR ART
India is basically an agricultural country, where majority of population is dependent on agriculture. Chemical fertilizers are considered as an essential input to Indian agriculture for meeting the food grain requirements of the growing population of the country and bear a direct relationship with food grain production. The major chemical fertilizers are Ammonia, Urea, Di-Ammonium Phosphate (DAP), Monoammonium Phosphate (MAP) and Nitrogen-Phosphorus-Potassium (NPK) nutrients. Ammonia is the most important one because it is used as a base in the production of many chemical fertilizers. In India, more than 95% of produced Ammonia goes for Urea production and also there is a gap between Urea production and demand which is met by imports.
Raw materials or feedstock required for production of Urea and Ammonia are Natural Gas (NG), Naphtha, Fuel Oil (FO) and Coal. In India, raw materials used in major Urea plants are: NG and Naphtha. Considering the uncertainty about the pricing and tenure of natural gas supply, Indian government has explored the possibility of using coal gas through coal gasification route as an alternative feedstock. Over 70% of Ammonia production in China is from coal using coal gas as feedstock and the cost of synthesis gas is approximately 20%-30% less than current level of cost of natural gas. Creating coal based chemical fertilizer plants in India will create not only a remedy for feedstock price fluctuation but also will reduce the dependency on petroleum imports and enhance national energy security. Recently, Government of India’s announcement of reviving few old

chemical fertilizer plants using coal gasification technology is another motivation for the present art.
Gasification of carbonaceous matter such as coal, gas, oil is a very well-known and matured process that converts feed into synthesis gas also called coal gas which basically contains Carbon monoxide (CO), Hydrogen (H2), Methane (CH4), Carbon Dioxide (CO2) and other trace elements. CO and H2 are the main building blocks for chemical products such as Methane, Methanol, Liquid fuels and Ammonia (NH3). Global statistics shows that there are many gasification plants for producing chemicals from coal. China is leading in terms of number of gasification plants, capacity and product profile. China is also the topper for producing chemical fertilizers from its coal reserves. The process technologies related to gasification, available throughout the globe are mostly suitable for low ash coals. But the ash content in Indian coals are higher at more than 40%. None of the global coal gasification technologies have been proven for using 100% high ash Indian coal. Hence it is essential to develop a process technology for processing high ash Indian coals to generate coal gas and thereby producing Ammonia and Urea.
European patent publication, EP0126961 A2, discloses a method of producing Ammonia from coal gasification using fluidized bed gasifier. The patent does not refer to bubbling fluidized bed and high ash coals. From the patent specifications it is clear that mixture of air and Oxygen is used as fluidizing medium which is different from present art. Present art uses mixture of CO2 and Oxygen (O2). Nitrogen (N2) required for Ammonia reactor is supplied in the form of air which is fed to gasifier in the European patent, whereas in the present application the N2 gas is supplied separately from air separation unit. The European patent does not claim any production of urea and produced CO2 gas reuse for urea production.
US patent, US 20060228284A1 ( also available as WO2006110422A2), describes a process of Ammonia production using any general type of oxy blown gasification process without any other fluidizing medium, as used in an entrained flow gasifier. However, in the present application, the type of

gasification used is bubbling fluidized bed and fluidizing medium used is mixture of CO2 and O2 gas. The US patent does not claim any production of urea and reuse of the produced CO2 gas for urea production.
Chinese patent, CN1608993A, discloses a process of combining coal gases that are generated from different kinds of gasification processes such as entrained flow and fluidized bed to make a suitable gas for ammonia production. The Chinese patent does not claim any bubbling fluidized bed process and any mixture of CO2 and O2 for fluidization, whereas the present invention clearly indicates the use of bubbling fluidized bed in presence of mixture of CO2 and O2 gas.
Canadian patent, CA2601447A1, discloses a method of producing Ammonia using Hydrogen from gasification process and N2 from air separation unit, but it does not claim any type of gasification process such as fluidized bed or entrained flow or any mixture of CO2 and O2 as fluidizing medium as in the present invention.
US patent, US8679439B2, claims the process of converting biomass into ammonia using fluidized bed gasification whereas the present invention deals with high ash coals. The US patent claims the usage of O2 and steam as fluidizing medium whereas in present invention mixture of CO2 and O2 gas is used as fluidizing medium. CO2 gas is separated in pressure swing absorbers in the US patent whereas in the present art acid gas removal unit is used to separate CO2 from coal gas. .
US patent, US5900224, describes the gasification of waste materials in two fluidized bed gasifiers operating at high temperature and low temperature where fluidizing medium is Oxygen and Oxygen enriched air respectively along with required steam, whereas in present invention only one bubbling fluidized bed gasifier is used for gasifying high ash coals, mixture of CO2 and O2 gas is used for fluidization. The US patent does not disclose production of urea and reuse of CO2 for urea production. The US patent does not describe any ammonia reactor and urea reactor, whereas present art describes ammonia and urea production.

US patent, US4261856, discloses the process of converting coal into coal gas that is suitable straight away for ammonia production using steam and air as fluidizing medium for gasification. In the US patent it is mentioned to play with steam and air ratio in the gasifier for attaining N2/H2 ratio of 1:3. Whereas in present art, it is proposed to use air separation unit, shift reactors, acid gas removal unit and pressure swing adsorbers for generating coal gas suitable for ammonia production.
US patent, US4524056 (or its equivalent EP0130846A2), describes a process utilizing steam and air as fluidizing medium for producing coal gas, where as in present invention fluidizing medium is a mixture of CO2 gas and O2. In the US patent, after shift reactor and CO2 removal, the coal gas is mixed with H2 rich gas to form a suitable gas for ammonia production. Whereas in the present invention, no external H2 rich gas is used for making coal gas suitable for ammonia production. The US patent does not claim a production of urea and reuse of produced CO2 gas for urea production.
OBJECTS OF INVENTION
It is therefore an object of this invention to propose a process for the production of Urea from high ash coal.
It is a further object of this invention to propose a process for the production of Urea from high ash coal which uses an oxy blown bubbling fluidized bed gasification process in which CO2 gas is used for coal lock and receiver vessels pressurization, mixture of CO2 gas and Oxygen gas is used to transport fluid and Oxygen source.
Another object of this invention is to propose a process for the production of Urea from high ash coal which utilizes an Air separation unit which generates O2 gas and N2 gas where O2 gas is used as Oxygen source for gasification reaction and N2 gas is used as feed gas for Ammonia reactor.
Yet another object of this invention is to propose a process for the production of Urea from high ash coal in which an oxidant mixture of CO2 gas and O2 gas is further used for gasification reaction and coal transportation.

A further object of the present invention is to propose a shift reaction system after coal gas heat recovery and coal gas clean-up in which CO content in the coal gas converted into H2.
A still further object of the invention is to propose an acid gas removal unit at downstream of shift reaction system where H2S and CO2 gets removed from coal gas leaving major Hydrogen content in the coal gas.
Yet another objective of the present art is to propose a CO2 gas compression system in which CO2 gas from acid removal system is further pressurized in order to cater gasification reaction needs, lock and receiver vessel pressurization needs and Urea reactor needs.
Yet another object of the invention is to include an Ammonia reactor system at the outlet of feed gas compression system where compressed N2 gas and H2 gas entered and converted into Ammonia.
Another object of the present invention is to add Urea reactor at the downstream of Ammonia reactor system in which liquid Ammonia and CO2 gas enters as feed and get converted into Urea.
These and other objects and advantages of the invention will be apparent to a person skilled in the art on reading the ensuing description in conjunction with the accompanying drawings.
SUMMARY OF INVENTION
The present invention relates to a process for the production of Urea from high ash coal. The invented process contains several process subsystems like air separation, coal gasification, oxidant mixing, coal gas heat recovery, coal gas clean-up, shift reaction, acid gas removal, CO2 gas compression, raw gas compression, Ammonia reactor and Urea reactor. As the present art objective is to avoid N2 in the gasification reactor which is the first process system of total process, the coal gas separation and further conversion into chemical fertilizer becomes trouble-free from Nitrogen gas. CO2 gas is used for coal lock and receiver pressure vessels pressurization purpose, whereas mixture of CO2 and Oxygen is used as coal transportation medium and gasification oxidant. CO2 as

a reactant in the gasifier increases Boudouard reaction in which CO2 reacts with carbon content of coal to give Carbon monoxide (CO). The resulting coal gas from bubbling fluidized bed gasifier goes through various sections like heat recovery, gas filter and gas clean-up for removing heat, particulates and other minor components. In the next step of the process, CO content of coal gas gets converted into H2 in shift reaction system. Outlet of shift reaction system goes to acid gas removal unit, where CO2 and H2S gets removed from coal gas as separate gases. Pressure swing adsorption system which comes next allows only H2 gas through adsorption beds which then combines with N2 gas from Air separation unit at 3:1 mole ratio in a raw gas compressor. The compressed raw gas gets converted into Ammonia in an Ammonia reactor system. Liquid Ammonia from Ammonia reactor system mixes with CO2 gas from CO2 gas compression system at a mole ratio of 2:1 to 4:1 (NH3:CO2) in a Urea reactor system for producing Urea. The mole ratio of NH3: CO2 at the urea reactor inlet is depends on the technology is used. The pure H2 gas from pressure swing adsorption system is also best suitable for fuel cell application or H2 needs of petrochemical or oil refineries. Shift reaction and Ammonia conversion reactions are exothermic nature and hence product gas contains lot of heat which is used to convert boiler feed water into steam in heat exchangers. In the overall process, optimum steam utilization is possible between steam generation sources viz coal gas after gasification, gas after shift reactors and gas after Ammonia reactor steam consumers viz gasification reactor, shift reactor inlet gas heater, steam for shift reaction, raw gas heater, and steam for acid gas removal unit.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Shows the present process of converting high ash Indian coals into Urea via Ammonia conversion
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a process for the production of Urea from high ash coal and a system therefor.
In accordance with this invention is provided a method for the production of Urea from high ash coal, said method comprises the steps of converting high

ash Indian coal into synthesis gas or coal gas under oxy blown gasification conditions in a gasifier (15),
said coal gas along with particulates being further driven to cyclone(19) where particulates are separated as cyclone bottom(20) and gas as cyclone outlet gas(21),
reducing the temperature of the cyclone outlet gas (21) to generate Economizer outlet gas (26) at around 280oC, which enters a Gas filter (31) to get further cleaned up to generate Gas Filter outlet coal gas (32),
allowing the Gas Filter outlet coal gas (32) to pass through a gas cleaning unit, GCU (33) to produce GCU outlet gas (34) followed by preheating GCU outlet gas (34) to 150oC;
said GCU outlet gas further moving to shift reaction system to generate LTS separator gas (67),
said LTS separator gas (67) further moving to acid gas removal unit, AGR (68), and leaving as AGR clean gas (71),
said AGR clean gas (71) further flowing to pressure swing adsorption beds PSA (77), for adsorbing coal gas components except H2 which passes through PSA beds and forms H2 product (78),
said H2 product (78) along with N2 product (37) flowing to raw gas compressor (79) to form compressed raw gas (80), followed by heating to form hot raw gas (84, which enters an Ammonia reactor (85) to form Ammonia gas (86), followed by condensing the same to form Liquid Ammonia (92),
subjecting said liquid Ammonia (92) to reaction with CO2 (74) in an Urea reactor (93) to obtain Urea (94).
The invention involves a process for gasification of high ash Indian coal for producing synthesis gas suitable for producing Urea, a chemical fertilizer. Coal (1) gets filled into coal hopper (2), an ambient atmospheric pressure vessel, from coal conveying system. Coal further transfers from coal hopper to a coal lock (4) through coal hopper outlet line (3). Coal lock is a pressure vessel which gets pressurized with CO2 gas by coal lock pressurization line (5). Before connecting

coal lock with coal hopper by operating valves in the coal hopper outlet line, Coal lock depressurizes to atmospheric pressure by venting CO2 gas using coal lock vent (6). When coal lock is filled with coal up to required level, coal lock starts re-pressurizing with CO2 gas.
Coal further travels from coal lock to coal receiver (8) through coal lock outlet line (7). Coal receiver is also a pressure vessel which gets pressurized with CO2 gas by coal receiver pressurization line (9). Before connecting coal lock with coal receiver, it is very important to ensure Coal lock pressure is equal to or more than coal receiver pressure. Coal receiver gets connected with coal lock for transferring coal whenever coal receiver registers low level. Once coal lock registers low level, coal lock gets disconnected from coal receiver and starts reconnecting with coal hopper for transferring coal. Provision of additional coal locks and coal receivers improves the reliability, availability and maintainability of coal feeding system. Coal further transfers from coal receiver outlet (10) to a coal feeder (11). Coal feeder discharges coal to an ejector (13) through coal feeder outlet line (12). Ejector utilizes transport oxidant (44) as driving fluid for transferring coal to gasifier (15).
Steam and Oxidant mixture (17) and coal from ejector outlet (14) are the feed materials to the Gasifier (15) which produces coal gas or synthesis gas. Gasifier (15) is a pressurized fluidized bed reactor which operates in bubbling fluidization zone. CO2 as a reactant in the gasifier increases Boudouard reaction in which CO2 reacts with carbon content of coal to give Carbon monoxide (CO).The outlet coal gas from the gasifier contains not only fuel gases such as Hydrogen (H2), Carbon Monoxide (CO) and minor Methane (CH4) but also contains Carbon dioxide (CO2), Nitrogen (N2), Water (H2O), Ammonia (NH3), Hydrogen Sulphide (H2S), Hydrogen Cyanide (HCN), particulates and trace metals like Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K), Lead (Pb), Vanadium (V). NH3 and N2 concentrations in coal gas is due to gasification reaction between Nitrogen content of coal and Oxidant in the gasifier. The level of concentrations of NH3 and N2 are negligible as nitrogen in Indian coal is also in negligible amount

ranging from 0.6 to 1 % weight. Similar way, H2S content in coal gas is also at negligible level as Indian coal contains sulfur content in the order of 0.5% weight.
The total ash content of the coal gets separated into heavier ash due to gravity and lighter ash due to elutriation in the Gasifier (15). Heavier ash called bottom ash (16) comes out of Gasifier as a bottom product and lighter ash called fly ash exits along with synthesis gas from Gasifier. The coal gas from Gasifier outlet (18) at a higher temperature of around 1000o C passes through a Cyclone (19) in which major fly ash content gets removed from cyclone bottom (20). The cyclone outlet gas (21) moves to Heat Recovery Boiler, HRB (22) where coal gas heats the preheated boiler feed water (29) to form saturated steam (30). Coal gas temperature falls from high temperature to intermediate temperature in the HRB. The fly ash gets collected in the coal gas inlet side of HRB due to flow direction change as HRB fly ash (23). HRB outlet coal gas (24) passes through the Economizer (25) where coal gas temperature gets further reduced by exchanging heat to boiler feed water (28) where it gets preheated before entering HRB. The fly ash collected in the economizer coal gas inlet side is rejected as economizer fly ash (27). The economizer outlet gas (26) at around 280oC temperature enters to a gas filter (31) where all the fly ash gets removed up to desired level. Gas filter is a metallic filter which has regeneration capability and collected fly ash removal facility at bottom. Gas filter outlet gas (32) gets further cleaning with respect to NH3, HCN and other trace elements like Ca, Mg, Na, K, Pb, V in a gas cleaning unit, GCU (33). In GCU ultimately the gas gets purified in order to meet high temperature shift reactor, HTSR (51), inlet specifications with respect to catalyst and gets heated up to around 150oC using steam. After GCU, coal gas composition changes to components H2, CO, CH4, CO2, H2O and traces of N2, H2S.
GCU outlet gas (34) moves forward to shift reaction section which starts with heater (47) where inlet gas gets heated to around 3700 C using steam generator-1 outlet gas (54). The heater outlet gas (48) combines with HTSR steam (49) to form HTSR inlet gas (50). The selected temperature and pressure of HTSR steam

equals to that of heater outlet gas. The quantity of HTSR steam is excess of theoretical requirement as per below chemical reaction (R1).
H2O + CO ↔H2 + CO2 Water gas shift reaction--(R1)
In HTSR (51), steam reacts with CO content of coal gas to produce H2 and CO2 as per chemical reaction (R1) on a sour HTSR catalyst. As H2S is not removed in GCU, sour HTSR catalyst is chosen as it can work even in the presence of H2S. As the CO conversion is at the order of 75% in HTSR, outlet gas from HTSR contains around 2- 4% by volume of CO in HTSR product gas (52). As the reaction (R1) is exothermic nature, lot of heat energy is generated in HTSR. As a result, HTSR product gas (52) is at a higher temperature and this heat is used for producing steam in steam generator-1 (53). Steam generator-1 outlet gas (54) further gets cooled by exchanging heat with GCU outlet gas (34) in heater (47). Heater outlet product gas (55) moves to a HTSR gas-liquid separator (56) where condensed water separates out as HTSR condensate (57) and gas separates out as HTSR separator gas (58). HTSR separator gas combines with LTSR steam (59) to form LTSR inlet gas (60). The selected temperature and pressure of LTSR steam equals to that of HTSR separator gas. The quantity of LTSR steam is in excess of theoretical requirement as per chemical reaction (R1).
In Low Temperature Shift Reactor, LTSR (61), steam reacts with remaining CO content of coal gas to produce H2 and CO2 as per chemical reaction (R1) on a sour LTSR catalyst. As the reaction (R1) is exothermic nature, considerable heat energy is generated in LTSR. As a result, LTSR product gas (62) is at a higher temperature and this heat is used for producing steam in steam generator-2 (63). Steam generator-2outlet gas (64) further moves to a LTSR gas-liquid separator (65) where condensed water separates out as LTSR condensate (66) and gas separates out as LTSR separator gas (67).
Coal gas after shift reaction section contains components of H2, CH4, CO2, N2, H2O and H2S. Negligible unconverted CO presence is also expected in the coal gas after shift reaction system. LTSR separator gas (67) goes to acid gas removal unit, AGRU(68) in which it is in contact with commercially available solvents

such as Ethanol Amines and separates CO2 and H2S from coal gas as AGR CO2(69) and AGR H2S (70). AGR H2S can be utilized for producing pure sulfur. AGR CO2is further pressurized up to the order of 200 bar by CO2 compressor (72) for further usage of CO2. Compressed CO2 (73) splits into excess CO2 (95), Urea CO2 (74) and Oxidant and Pressurization CO2 (OPC) gas (75). OPC gas further splits into Oxidant CO2 (39) and Pressurization CO2 gas (40). The Pressurized CO2 gas is further used for pressurization of Coal lock and Coal receiver using coal lock pressurization line (5) and coal receiver pressurization line (9). The pressurized CO2 gas also used for pressurization of lock and receiver vessels in the bottom ash and fly ash removal mechanisms. Excess CO2 (95) from the system can be taken out for further usage.
AGR clean gas (71) flows further to a hydrogen separation system. Hydrogen separation system uses pressure swing adsorption beds (77), PSA, for adsorbing coal gas components except H2. The H2 gas passes through PSA beds and forms H2 product (78) and PSA Waste gas (76). The PSA waste gas contains gas components such as CH4, N2, H2O and CO that are adsorbed by PSA adsorbent beds and detach from PSA beds during desorption step in reverse flow. The PSA waste gas stream can be further used for heating purposes as it contains fuel gas components CO and CH4.
Raw gas compressor (79) compresses H2 product (78) and N2 product (37) up to around 200 bar pressure and discharges it as compressed raw gas (80). Compressed raw gas further heated up in raw gas heater (83) up to around 500oC temperature using steam as heating medium forms hot raw gas (84). The hot raw gas gets admitted into Ammonia reactor (85) where N2 and H2gets converted into Ammonia as per chemical reaction (R2) below.
N2 + 3 H2↔ 2 NH3Ammonia conversion reaction ------ (R2)
As the reaction (R2) is exothermic nature, lot of heat energy is generated in Ammonia reactor. As a result, Ammonia reactor product gas (86) is at a higher temperature and this heat is used for producing steam in steam generator-3 (87). Ammonia gas steam generator product gas (88) moves to an Ammonia separator (89) where condensed Ammonia separates out as Liquid Ammonia (92) and

unconverted gas as recycle gas (90). Recycle gas gets compressed in recycle gas compressor (91) and discharges quench gas (81) which directly gets admitted back into Ammonia reactor beds as reactant and coolant. Commercially available Ammonia technology which uses N2 and H2 as feeds is considered for the present art.
Liquid Ammonia (92) at 200 bar pressure enters into a Urea reactor (93) along with UreaCO2 (74) for conversion of NH3 and CO2 into Urea product (94). Commercially available Urea technology which uses NH3 and CO2 as feeds is considered for the present art. The mole ratio of NH3:CO2 at the urea reactor inlet is depends on the technology is used. Typical ratios are from 2:1 to 4:1 on mole basis
Air separation unit (36) consumes compressed ambient air (35) as feed for producing O2 product (38) and N2 product (37). O2 product (38) further mixes with Oxidant CO2 (39) in an O2- CO2 mixing vessel (41) to form Oxidant (42). Oxidant further splits into transport oxidant (44) and raw oxidant (43). Raw Oxidant and gasification steam (46) combines in a Steam-Oxidant mixing vessel (45) to form steam and Oxidant mixture (17).

WE CLAIM:
1. A method for the production of Urea from high ash coal, said process
comprises the steps of converting high ash Indian coal into synthesis gas
or coal gas under oxy blown gasification conditions in a gasifier (15),
said coal gas along with particulates being further driven to cyclone(19)
where particulates are separated as cyclone bottom(20) and gas as cyclone
outlet gas(21),
reducing the temperature of the cyclone outlet gas (21) to generate
Economizer outlet gas (26) at around 280oC, which enters a Gas filter (31)
to get further cleaned up to generate Gas Filter outlet coal gas (32),
allowing the Gas Filter outlet coal gas (32) to pass through a gas cleaning
unit, GCU (33) to produce GCU outlet gas (34) followed by preheating GCU
outlet gas (34) to 150oC;
said GCU outlet gas (34) further moving to shift reaction system to
generate LTS separator gas (67),
said LTS separator gas (67) further moving to acid gas removal unit, AGR
(68), and leaving as AGR clean gas (71),
said AGR clean gas (71) further flowing to pressure swing adsorption beds
PSA (77), for adsorbing coal gas components except H2 which passes
through PSA beds and forms H2 product (78),
said H2 product (78) along with N2 product (37) flowing to raw gas
compressor (79) to form compressed raw gas (80), followed by heating to
form hot raw gas (84, which enters an Ammonia reactor (85) to form
Ammonia gas (86), followed by condensing the same to form Liquid
Ammonia (92),
subjecting said liquid Ammonia (92) to reaction with CO2 (74) in an Urea
reactor (93) to obtain Urea (94).
2. The method as claimed in claim 1, wherein said oxy blown gasification
conditions comprise providing a Steam and Oxidant mixture (17) as
fluidizing medium alongwith coal, in the gasifier (15).

3. The method of claim 1, wherein said synthesis gas generated in gasifier (15) contains CO, H2, CO2, H2O, CH4, NH3, H2S, HCN, N2 and other minor trace elements like Ca, Mg, Na, K, Pb, V.
4. The method as claimed in claim 3, wherein said cyclone outlet gas (21) heat content is utilized to produce saturated steam (30) from boiler feed water (28) using combination of two heat exchangers called Heat Recovery Boiler (22) & Economizer(25).
5. The method as claimed in claim 1, wherein said Economizer outlet gas (26) enters a gas filter (31) where all the fly ash gets removed up to desired levels.
6. The method as claimed in claim 1, wherein said Gas filter outlet coal gas (32) gets further cleaned up with respect to NH3, HCN and trace elements like Ca, Mg, Na, K, Pb, V in GCU (33) by producing GCU outlet gas (34).
7. The method as claimed in claim 4, wherein said GCU outlet gas (34) moves to shift reaction system where CO content of the coal gas gets converted into H2, said shift reaction system comprising of HTS reactor (51), LTS reactor (61), its associated heat recovery equipment’s and gas-liquid separators.
8. The method as claimed in claim 5, wherein said LTS separator gas (67) further moves to acid gas removal unit, AGR (68), where its H2S and CO2 components gets separated as AGR H2S (70) and AGR CO2 (69) using solvents such as Ethanolamine, and said LTS separator gas (67) leaves as AGR clean gas(71).

9. The method as claimed in claim 1, wherein said AGR clean gas flows to pressure swing adsorption beds, PSA (77), for adsorbing coal gas components which get detached during pressure swing or reduction and flow in reverse direction as PSA waste gas(76).
10. The method as claimed in claim 9, wherein said PSA waste gas (76) basically contains CH4, H2O, N2 and CO which can be used further for heating purpose.
11. The method as claimed in claim 1, wherein said H2 product (78) along with N2 product (37) at a mole ratio of 1:3 (H2: N2), flows to raw gas compressor (79) for compression upto around 200 bar pressure to form compressed raw gas (80).
12. The method as claimed in claim 11, wherein said compressed raw gas (80) gets heated up in raw gas heater (83) up to 500oC using steam as heating medium to form hot raw gas (84).
13. The method as claimed in claim 12, wherein said Ammonia gas (86) exchanges heat for producing steam in steam generator-3 (87) and Steam generator-3 outlet gas (88) moves to an Ammonia separator (89) where condensed Ammonia separates out as Liquid Ammonia (92) and unconverted gas as recycle gas (90), said recycle gas gets compressed in an recycle gas compressor (91) and discharges quench gas (81) which directly gets admitted back into Ammonia reactor beds as reactant and coolant.

14. The method as claimed in claim 1, wherein said liquid Ammonia (92) at 200 bar pressure enters into the Urea reactor (93) along with CO2 (74) with a mole ratio of 2:1 to 4:1(NH3:CO2.
15. The method as claimed in claim 1, wherein said AGR CO2 (69) is further pressurized by CO2 compressor (72) upto order of 200 bar pressure to obtain compressed CO2 (73) for further usage in pressurization of Coal lock and Coal receiver using coal lock pressurization line (5) and coal receiver pressurization line (9) and for pressurization of lock and receiver vessels in the bottom ash and fly ash removal mechanisms.

16. The method as claimed in claim 15, wherein said compressed CO2 (73) splits into excess CO2 (95), Urea CO2 (74) and Oxidant and Pressurization CO2 (OPC) gas (75) and OPC gas further splits into Oxidant CO2 (39) and Pressurization CO2 gas (40).
17. The method as claimed in claim 11, wherein said N2 product (37) is produced as a product along with O2 product (38) in an air separation unit (36) which consumes compressed ambient air (35) as feed.
18. The method as claimed in claim 17, wherein said O2 product (38) further mixes with Oxidant CO2 (39) in an O2 - CO2 mixing vessel (41) to form Oxidant (42) which further splits into transport oxidant (44) and raw oxidant (43), raw Oxidant and gasification steam (46) combining in a Steam-Oxidant mixing vessel (45) to form steam and Oxidant mixture (17).