Description:FIELD
The present disclosure relates to methanol production. Particularly, the present disclosure relates to a method and a system for the preparation of methanol from coal.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Hydrocarbons are used as a raw material and fuel in various industries such as chemical, petrochemical, rubber, and plastic industries. Hydrocarbons can be obtained from fossil fuels; however, fossil fuels have finite reserves. Furthermore, the direct combustion of fossil fuels leads to air pollution and in turn to global warming. Thus, there is a need for alternative energy sources or clean sources of energy. Hydrogen is a clean source of energy, however is associated with drawbacks of difficulty in storage, handling, and transportation. There is also an enormous cost associated with hydrogen production and usage, as it is extremely volatile and potentially explosive, requires high-pressure equipment, costly and non-existent infrastructure, special materials to minimize diffusion and leakage, and also requires extensive safety. Comparatively, methanol is another alternative which can be blended with gasoline or diesel and used as fuels. Methanol can also be used in the form of highly efficient fuel cell batteries. Furthermore, Methanol and its derivative products such as acetic acid and formaldehyde obtained through chemical reactions are used as base materials in acrylic plastic; synthetic fabrics and fibers used to make clothing; and also in adhesives, paint, and plywood that used in construction; and as a chemical agent in pharmaceuticals and agrichemicals.
Conventionally, methanol can be produced from incomplete combustion (or catalytic reforming) of fossil fuels, mainly natural gas (methane) and coal. However, most of the coal reserves have higher ash contents, and therefore processing and utilization of such coal is difficult, as the process is not environment friendly.
Furthermore, the non-coking type coal of grade G-1 to grade G-15 has ash contained in the range of 15 wt% to 52 wt% and typically in India most of the coal reserves available have ash in the range of 30-45 wt%. Due to this high ash content in the coal, the conversion process of coal to methanol is technically difficult. Also, the removal of impurities from the syngas produced from coal poses challenges.
Furthermore, the worldwide prevalent gasification technologies such as entrained flow and moving bed gasifiers are not suitable for high ash coal and also handling coal of sizes 6 mm and lower. Such technologies are also quite sensitive to variations in coal quality. Such technology needs washing of coal and blending of the high-grade coal for its satisfactory operation. Also, the above prevalent technologies operate at very high pressures greater than 20 barA (absolute pressure) leading to more complex equipment and system and hence, the overall process for conversion of coal to methanol needs to be established for gasifier technology suitable for high ash coal (>30% ash) and to produce clean syngas that are suitable for chemical production.
There is, therefore, felt a need to provide a method and a system for the preparation of methanol from coal that overcomes the above-mentioned drawbacks, or at least provides an alternative solution.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.
Another object of the present disclosure is to provide a method for the preparation of methanol from coal.
Still, another object of the present disclosure is to provide a simple method for the preparation of methanol from coal.
Yet another object of the present disclosure is to provide a cost-effective method for the preparation of methanol from coal.
Still, another object of the present disclosure is to provide a method for the preparation of methanol from high-ash coal that improves the coal-to-methanol conversion efficiency.
Still, another object of the present disclosure is to provide a system for the preparation of methanol from coal.
Yet another object of the present disclosure is to provide a system for the preparation of methanol from coal which reduces the overall operating cost.
Still, another object of the present disclosure is to provide a system for the preparation of methanol from coal which requires a lower maintenance.
Yet another object of the present disclosure is to provide a system for the preparation of methanol from coal which has minimal downtime.
Another object of the present disclosure is to provide a system that is able to handle coal of sizes below 6 mm and coal with different ash content.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a method for the preparation of methanol from coal, the method comprising the following steps:
i. gasifying coal in at least one fluidized bed gasification unit by treating a mixture of coal, super-heated steam, and oxygen at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. cooling and filtering the crude syngas to obtain a partially refined syngas (PRS);
iii. removing moisture partially from the partially refined syngas (PRS) to obtain a moisture-deficient partially refined syngas (MDPRS), followed by cleaning to obtain partially cleaned syngas (PCS);
iv. reacting the partially cleaned syngas (PCS) with a steam and catalyst in a predetermined ratio at a second predetermined temperature and at a second predetermined pressure, followed by amine treatment to obtain partially purified syngas (PPS) and cooling the partially purified syngas (PPS) to a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
v. compressing the cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS);
vi. removing trace sulfur impurities from the compressed partially purified syngas (CPPS) to obtain compressed purified syngas (CPS);
vii. synthesizing a product mixture of crude methanol, water, and unreacted syngas from the compressed purified syngas (CPS);
viii. separating the unreacted syngas and water from the product mixture to obtain a crude methanol; wherein a separated unreacted syngas is recycled back to at least one methanol synthesis unit; and
ix. distillation of the crude methanol in at least one methanol distillation unit to obtain methanol.
In an embodiment of the present disclosure, coal is at least one selected from Indian coal, South African coal, and Indonesian coal. The coal has an ash content of up to 52 mass%. The Indian coal is selected from grades G-1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G12, G13, G14, G-15 and combinations thereof; the South African coal is selected from grades RB-1, RB-2, RB-3 and combinations thereof.
In accordance with an embodiment of the present disclosure, the coal has a particle size in the range of 0.1 mm to 8 mm.
In accordance with an embodiment of the present disclosure, the ratio of the super-heated steam to the coal (S/C) is in the range of 0.7 to 1.0 and the ratio of the oxygen to the coal (O/C) is in the range of 0.35 to 0.50.
In accordance with an embodiment of the present disclosure, the first predetermined temperature is in the range of 900 °C to 1050 °C and the first predetermined pressure is in the range of 1.1 barA to 8 barA.
In accordance with an embodiment of the present disclosure, the cooling of the crude syngas is done in a syngas cooling system. The crude syngas is cooled to a temperature in the range of 180 °C to 300 °C.
In accordance with an embodiment of the present disclosure, during filtration of the crude syngas in step (ii), fly ash is separated by using cyclone separation to separate coarse fly ash particles, followed by using at least one candle filter to separate fine fly ash particles having a size less than 1 micron.
In accordance with an embodiment of the present disclosure, the cleaning in step (iii) is performed at a temperature in the range of 40 oC to 55 oC.
In accordance with an embodiment of the present disclosure, in cleaning in step (iii), the moisture-deficient partially refined syngas (MDPRS) is treated to remove the impurities, followed by sequentially removing tar containing heavy and light aromatics, acid washing, and removal of fouling agents, wherein the fouling agents include metals, organo-metallic compounds, and corrosion products.
In accordance with an embodiment of the present disclosure, the molar ratio of the steam to the carbon monoxide in the partially cleaned syngas (PCS) is in the range of 1.01 to 1.6.
In accordance with an embodiment of the present disclosure, the second predetermined temperature is in the range of 260 °C to 370 °C and the second predetermined pressure is in the range of 1.1 barA to 8 barA
In accordance with an embodiment of the present disclosure, the amine treatment comprises the steps of removal of acid gases and absorption of carbon dioxide (CO2) and hydrogen sulphide (H2S) at a pressure in the range of 1.1 barA to 8 barA; and at a temperature is in the range of 45 °C to 60 °C.
In accordance with an embodiment of the present disclosure, the trace sulfur impurities are removed from the compressed partially purified syngas (CPPS) using at least one catalyst selected from organic sulfur removal catalysts, inorganic sulfur removal catalysts, and metal carbonyl removal catalysts.
In accordance with an embodiment of the present disclosure, the synthesis of the product mixture in step (vii) comprises heating the compressed purified syngas (CPS) at a temperature in the range of 205 °C to 220 °C to obtain a heated compressed purified syngas (HCPS), and reacting the heated compressed purified syngas (HCPS) at a pressure in the range of 50 barA to 80 barA and at a temperature of less than 280 °C in the presence of a catalyst, wherein the catalyst is at least one selected from Copper, and Zinc supported on alumina.
In accordance with an embodiment of the present disclosure, the separation of the unreacted syngas and water in step (viii) is done by condensing, wherein the condensation is carried out at a temperature in the range of 20 °C to 50 °C and at a pressure in the range of 40 barA to 80 barA.
In accordance with an embodiment of the present disclosure, in step (ix) the distillation of crude methanol is for separating dissolved gases and low and high boiling impurities including moisture at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA.
In accordance with an embodiment of the present disclosure, the separated unreacted is recirculated back to the inlet of at least one methanol synthesis unit after the removal of crude methanol, and the excess part of the unreacted syngas is purged out from the system to flare or is passed to a combustor to generate utilities like steam.
The present disclosure also relates to a system for the preparation of methanol from coal. The system comprises:
i. at least one fluidized bed gasification unit, configured to receive a coal, super-heated steam, and oxygen and further configured to gasify the coal at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. at least one crude syngas cooling unit and at least one particle separation unit in fluid communication with the at least one fluidized bed gasification unit, configured for cooling and filtering the crude syngas to obtain a partially refined syngas (PRS);
iii. at least one condenser cum washing unit in fluid communication with the at least one particle separation unit, configured to receive the partially refined syngas (PRS), and further configured to separate moisture partially to obtain a moisture-deficient partially refined syngas (MDPRS);
iv. at least one gas cleanup unit in fluid communication with the at least one condenser cum washing unit, configured to receive the moisture-deficient partially refined syngas (MDPRS), and further clean to obtain a partially cleaned syngas (PCS), wherein the gas cleanup unit is at least one selected from a tar removal unit, an acid washing unit, and a primary guard bed unit;
v. at least one water-gas shift reactor unit in fluid communication with the at least one gas cleanup unit, configured to receive and react the partially cleaned syngas (PCS), steam and at least one catalyst, followed by amine treatment using at least one amine-based acid gas removal unit in fluid communication with the at least one water-gas shift reactor unit to absorb carbon dioxide (CO2) and hydrogen sulphide (H2S) to obtain a partially purified syngas (PPS); at least one cooling unit is configured to receive the partially purified syngas (PPS) to cool at a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
vi. at least one compressor unit in fluid communication with the at least one amine-based acid gas removal unit, configured to receive the cooled partially purified syngas and compress the cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS);
vii. at least one secondary guard bed unit in fluid communication with the at least one compressor unit, configured to receive the compressed partially purified syngas (CPPS) and remove trace sulfur impurities to obtain a compressed purified syngas (CPS);
viii. at least one methanol synthesis unit in fluid communication with the at least one secondary guard bed unit, configured to receive the compressed purified syngas (CPS) and synthesize a product mixture of crude methanol, water, and an unreacted syngas;
ix. at least one crude methanol separation unit in fluid communication with the at least one methanol synthesis unit, configured to receive the product mixture and separate the unreacted syngas and water to produce crude methanol; and
x. at least one methanol distillation unit in fluid communication with the at least one crude methanol separation unit, configured to receive the crude methanol and separate dissolved gases and impurities to obtain methanol.
In accordance with an embodiment of the present disclosure, the system comprises at least one coal crushing and feeding unit, configured for crushing coal to a particle size in the range of 0.1 mm to 8 mm and further feeding the crushed coal particles to at least one fluidized bed gasification unit.
In accordance with an embodiment of the present disclosure, the coal crushing and feeding unit comprises coal crushers, screening units, belt and bucket-type conveyors, coal hoppers, and a coal metering unit with coal feeders.
In accordance with an embodiment of the present disclosure, the coal hoppers are single or multiple lock hopper systems comprising at least two hoppers working in tandem to continuously supply the coal to the gasifier; wherein the coal is metered and fed using coal feeders that are volumetrically pre-calibrated for specific type of coal.
In accordance with an embodiment of the present disclosure, the fluidized bed gasification unit comprises crushed refractory-type bed material.
In accordance with an embodiment of the present disclosure, the crude syngas cooling unit is a vertical-design cooling unit with single or multiple passes.
In accordance with an embodiment of the present disclosure, the condenser cum washing unit comprises at least one indirect horizontal or vertical condenser and/or direct quench and condensing type washing unit which is at least one selected from the group consisting of a venturi scrubber, and single or multi-stage open or packed bed towers.
In accordance with an embodiment of the present disclosure, the tar removal unit and the acid washing unit is at least one selected from the group consisting of a single or multi-stage open or packed bed towers.
In accordance with an embodiment of the present disclosure, the amine-based acid gas removal unit comprises at least one amine absorber column and at least one amine regeneration column for the regeneration of the amine in a closed-loop circuit by using steam.
In accordance with an embodiment of the present disclosure, the secondary guard bed unit comprises multiple packed bed guard beds operating at a temperature in the range of 120 °C to 250 °C.
In accordance with an embodiment of the present disclosure, the methanol synthesis unit comprises a feed heater, a reactor with a pelleted catalyst bed, and a product cooler.
In accordance with an embodiment of the present disclosure, the crude methanol separation system comprises at least one condensing unit in fluid communication with the at least one methanol synthesis unit, configured to receive the product mixture and condense to separate the unreacted syngas to obtain a crude methanol comprising dissolved gases and impurities.
In accordance with an embodiment of the present disclosure, the at least one methanol distillation unit is configured to distill the crude methanol comprising dissolved gases and impurities at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA to obtain methanol.
In accordance with an embodiment of the present disclosure, the system comprises at least one steam generation unit for the generation of steam using heat rejected from the crude syngas cooling unit and from the methanol synthesis unit.
In accordance with an embodiment of the present disclosure, the system comprises at least one methanol purification unit in fluid communication with the methanol distillation unit, is configured to obtain methanol of the required specification.
In accordance with an embodiment of the present disclosure, the system comprises at least one methanol storage unit.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
A method and a system and for the preparation of methanol from coal of the present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a schematic representation of a system for the preparation of methanol from coal, in accordance with an embodiment of the present disclosure.
LIST OF REFERENCE NUMERALS USED IN DETAILED DESCRIPTION AND DRAWING
1000 System for the preparation of methanol from coal
10 coal crushing and feeding unit
100 fluidized bed gasification unit
200 crude syngas cooling unit
300 particle separation unit
400 condenser cum washing unit
500 gas cleanup unit
600 water-gas shift reactor unit
610 acid gas removal unit
700 compressor unit
800 secondary guard bed unit
900 methanol synthesis unit
910 crude methanol separation unit
920 methanol distillation unit
DETAILED DESCRIPTION
The present disclosure relates to a method and a system for the preparation of methanol from coal.
Embodiments of the present disclosure will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third, etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
Hydrocarbons are used as a raw material and fuel in various industries such as chemical, petrochemical, rubber, and plastic industries. Hydrocarbons can be obtained from fossil fuels; however, fossil fuels have finite reserves. Furthermore, the direct combustion of fossil fuels leads to air pollution and in turn to global warming. Thus, there is a need for alternative energy sources or clean sources of energy. Hydrogen is a clean source of energy, however is associated with drawbacks of difficulty in storage, handling, and transportation. There is also an enormous cost associated with hydrogen production and usage, as it is extremely volatile and potentially explosive, requires high-pressure equipment, costly and non-existent infrastructure, special materials to minimize diffusion and leakage, and also requires extensive safety. Comparatively, methanol is another alternative which can be blended with gasoline or diesel and used as fuels. Methanol can also be used in the form of highly efficient fuel cell batteries. Furthermore, Methanol and its derivative products such as acetic acid and formaldehyde obtained via chemical reactions are used as base materials in acrylic plastic; synthetic fabrics and fibers used to make clothing; and also in adhesives, paint, and plywood that used in construction; and as a chemical agent in pharmaceuticals and agrichemicals.
Conventionally, methanol can be produced from incomplete combustion (or catalytic reforming) of fossil fuels, mainly natural gas (methane) and coal. However, most of the coal reserves have higher ash contents, and therefore processing and utilization of such coal is difficult, as the process is not environment friendly.
Further, the non-coking type coal of grade G-1 to grade G-15 has ash contained in the range of 15 wt% to 52 wt% and typically in India most of the coal reserves available have ash in the range of 30-45 wt%. Due to this high ash content in the coal, the conversion process of coal to methanol is technically difficult. Also, the removal of impurities from the syngas produced from coal poses challenges.
Furthermore, the worldwide prevalent gasification technologies such as entrained flow and moving bed gasifiers are not suitable for high ash coal and also handling coal of sizes 6 mm and lower. Such technologies are also quite sensitive to variations in coal quality. Such technology needs washing of coal and blending of the high-grade coal for its satisfactory operation. Also, the above prevalent technologies operate at very high pressure (>20 barA) leading to more complex equipment and system and hence, the overall process for conversion of coal to methanol needs to be established for gasifier technology suitable for high ash coal (>30% ash) and to produce clean syngas that are suitable for chemical production.
To avoid the shortcomings of conventional coal-to-methanol production, the present disclosure provides a method and a system for the production of methanol from coal that offers advantages such as capable of processing coal with different and higher ash content, improved coal-to-methanol conversion efficiency, simple and easy to perform and operate, reliable and cost-effective and alleviates the drawbacks of the apparatus in the prior art.
The present disclosure provides a method and a system for the preparation of methanol from coal.
In an aspect, the present disclosure relates to a method for the preparation of methanol from coal. The method comprises the following steps:
i. gasifying coal in at least one fluidized bed gasification unit by treating a mixture of coal, super-heated steam, and oxygen at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. cooling and filtering the crude syngas to obtain a partially refined syngas (PRS);
iii. removing moisture partially from the partially refined syngas (PRS) to obtain a moisture-deficient partially refined syngas (MDPRS), followed by cleaning to obtain partially cleaned syngas (PCS);
iv. reacting the partially cleaned syngas (PCS) with a steam and a catalyst in a predetermined ratio at a second predetermined temperature and at a second predetermined pressure, followed by amine treatment to obtain partially purified syngas (PPS); and cooling the partially purified syngas (PPS) to a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
v. compressing the cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS);
vi. removing trace sulfur impurities from the compressed partially purified syngas (CPPS) to obtain compressed purified syngas (CPS);
vii. synthesizing a product mixture of crude methanol, water, and unreacted syngas from the compressed purified syngas (CPS);
viii. separating the unreacted syngas and water from the product mixture to obtain a crude methanol; wherein a separated unreacted syngas is recycled back to at least one methanol synthesis unit; and
ix. distillation of the crude methanol in at least one methanol distillation unit to obtain methanol.
The method is described in detail herein below:
In the first step, coal is gasified in at least one fluidized bed gasification unit by treating a mixture of coal, super-heated steam and oxygen at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas.
In accordance with the embodiment of the present disclosure, the coal is at least one selected from Indian coal, South African coal, and Indonesian coal. In an exemplary embodiment, the coal is Indian high ash coal. The coal has an ash content of up to 52 mass%. In an exemplary embodiment, the coal has an ash content of 35%.
In accordance with the embodiment of the present disclosure, the Indian coal is selected from grades G-1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G12, G13, G14, G-15 and combinations thereof.
In accordance with the embodiment of the present disclosure, the South African coal is selected from grades RB-1, RB-2, RB-3, and combinations thereof.
In accordance with the embodiment of the present disclosure, the coal is crushed to a particle size in the range of 0.1 mm to 8 mm with typical size +1mm to -8mm and max 20% coal fines with size less than 1mm, and thereafter gasified.
In accordance with the embodiment of the present disclosure, the coal is volumetrically re-calibrated for a specific type of coal before the gasification reaction.
In accordance with the embodiment of the present disclosure, the ratio of the super-heated steam to the coal (i.e., stem/coal (S/C)) is in the range of 0.70 to 1.0. In an exemplary embodiment, the ratio of super-heated steam to the coal (i.e., stem/coal (S/C)) is 0.85.
In accordance with the embodiment of the present disclosure, the ratio of oxygen to coal (i.e., Oxygen/coal (O/C)) is in the range of 0.35 to 0.50. In an exemplary embodiment, the ratio of oxygen to coal (i.e., Oxygen/coal (O/C)) is 0.40.
In accordance with the embodiment of the present disclosure, the “C” in the superheated steam to coal ratio or in oxygen to the coal ratio represents the “carbon” in coal, on “as received basis” (% by mass). The “C” value is obtained from the ultimate analysis of the respective coal samples as per the ASTM D 5373 2021 standard.
In accordance with the embodiment of the present disclosure, the first predetermined temperature is in the range of 900 °C to 1050 °C. In an exemplary embodiment, the first predetermined temperature is 970 °C.
In accordance with the embodiment of the present disclosure, the first predetermined pressure is in the range of 1.1 barA to 8 barA. In an exemplary embodiment, the first predetermined pressure is 5.4 barA.
In the second step, the crude syngas is cooled and filtered to obtain a partially refined syngas (PRS).
In accordance with the embodiments of the present disclosure, the cooling of the crude syngas is done in a syngas cooling system to generate steam from the system. The crude syngas is cooled to a temperature in the range of 180 °C to 300 °C. In another embodiment, the syngas is cooled to a temperature of 180 °C to 220 °C.
In accordance with the embodiment of the present disclosure, during filtration of the crude syngas, the crude syngas is passed through a particle separation unit, in which the fly ash is separated from the cooled crude syngas by subjecting the cooled crude syngas to cyclone separation to separate coarse fly ash particles, followed by candle filtering to separate fine fly ash particles of size less than 1 micron. The candle filter works as a dust filter to remove the excess fly ash of fine sizes.
In an exemplary embodiment of the present disclosure, for the production of methanol from coal of a one metric ton per day capacity, the total dust load at the outlet of the cyclone separator and the candle filter is less than 10 mg/Nm3.
In the third step, moisture from the partially refined syngas is partially removed to obtain a moisture-deficient partially refined syngas (MDPRS). Thereafter, the moisture-deficient partially refined syngas (MDPRS) is cleaned to obtain partially cleaned syngas (PCS).
The crude syngas after the dust removal unit is passed through a quench scrubber to generate the moisture-deficient partially refined syngas and then the cleaning is performed at a temperature in the range of 40 °C to 55 °C to obtain the partially cleaned syngas (PCS).
In accordance with the embodiments of the present disclosure, the partially refined syngas (PRS) has a moisture content in the range of 35% to 50%. In another embodiment, the partially refined syngas has a moisture content in the range of 45% to 50 %.
In accordance with the embodiment of the present disclosure, the moisture content in the moisture-deficient partially refined syngas (MDPRS) is in the range of 1.2 % to 8.8%. In an exemplary embodiment, the moisture content in the moisture-deficient partially cleaned syngas (MDPRS) is 1.84 %.
In accordance with the embodiments of the present disclosure, moisture-deficient partially refined syngas (MDPRS) is treated to remove the impurities, sequentially followed by removal of tar, acid washing, and removal of fouling agents in a primary guard bed unit. In the gas cleanup unit, the saturated syngas is treated to remove the impurities; a tar is removed through a tar removal system, followed by acid washing, and further treatment in the primary guard bed unit to remove the fouling agents.
In accordance with the embodiments of the present disclosure, the fouling agents include metals, organo-metallic compounds, and corrosion products.
In the fourth step, partially cleaned syngas (PCS) and steam are reacted in the presence of a catalyst in a predetermined ratio at a second predetermined temperature and a second predetermined pressure, followed by an amine treatment to obtain a partially purified syngas (PPS), and cooling the partially purified syngas (PPS) to a temperature in the range of 5°C to 15 °C to obtain a cooled partially purified syngas.
In accordance with the embodiments of the present disclosure, a molar ratio of the steam to carbon monoxide in partially cleaned syngas (PCS) is in the range of 1.01 to 1.6. In an exemplary embodiment, the molar ratio of the steam to carbon monoxide in the partially cleaned syngas (PCS) is 1.03.
In accordance with the embodiments of the present disclosure, the second predetermined temperature is in the range of 260 °C to 370 °C. In an exemplary embodiment, the second predetermined temperature is 320°C.
In accordance with the embodiments of the present disclosure, the second predetermined pressure is in the range of 1.1 barA to 8 barA. In an exemplary embodiment, the second predetermined pressure is 4.5 barA.
In accordance with the embodiments of the present disclosure, the amine treatment comprises the steps of removal of acid gas and absorption of carbon dioxide (CO2) and hydrogen sulphide (H2S) at a pressure of 1.1 barA to 8 barA and at a temperature in the range of 45 °C to 60 °C to obtain the partially purified syngas (PPS). In an exemplary embodiment, amine treatment is performed at a pressure of 4 barA and at a temperature of 45 °C.
The partially purified syngas (PPS) is then processed through a cooling unit to reduce the temperature of the syngas to 15 °C. Further, the cooled syngas is passed through a gas-liquid separator to reduce the moisture content from the partially purified syngas (PPS) and then subsequently passed to the compressor unit.
In the fifth step, the cooled partially purified syngas is compressed to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS). In an exemplary embodiment, the syngas is compressed at a pressure of 73 barA.
In the sixth step, trace sulfur impurities are removed from the compressed partially purified syngas (CPPS) to obtain a compressed purified syngas (CPS).
In accordance with the embodiment of the present disclosure, the partially purified syngas (PPS) is compressed using a gas compressor to a pressure of 40 barA to 80 barA to obtain the compressed partially purified syngas (CPPS). Further, the trace sulfur impurities present in the CPPS are removed using at least one catalyst selected from organic sulfur removal catalyst, inorganic sulfur removal catalysts, and a catalyst for the removal of metal carbonyls to obtain the compressed purified syngas (CPS). The compressed purified syngas have sulfur impurities of less than 50ppb after the removal of sulfur in this purification stage.
In the seventh step, the compressed purified syngas (CPS) is processed for synthesizing a product mixture containing crude methanol, water and unreacted syngas.
In the eighth step, the unreacted syngas and water are separated from the product mixture to obtain crude methanol and the unreacted syngas is recycled back to at least one methanol synthesis unit and some excess part is purged out from the system to flare or to is passed to a combustor to generate utilities like steam.
In accordance with the embodiment of the present disclosure, the separated unreacted syngas is recirculated back after the removal of crude methanol and taking excess purged steam out of the system to flare. The excess moisture present in the unreacted syngas is removed to achieve better overall carbon conversion.
In accordance with the embodiment of the present disclosure, the synthesis of the product mixture in seventh step comprises heating the compressed purified syngas (CPS) at a temperature in the range of 205 °C to 220 °C to obtain heated compressed purified syngas (HCPS), then reacting the heated compressed purified syngas (HCPS) at a pressure in the range of 50 barA to 80 barA and at a temperature of less than 280 °C in the presence of a catalyst. Wherein, the catalyst is at least one selected from Copper, and Zinc supported on alumina.
In accordance with another embodiment of the present disclosure, the compressed purified syngas (CPS) is mixed with the recycled stream consisting of the separated unreacted syngas and then heated to a temperature in the range of 205 °C to 220 °C to obtain heated compressed purified syngas (HCPS), and reacting the heated compressed purified syngas (HCPS) at a pressure in the range of 50 barA to 80 barA and at a temperature of less than 280 °C in the presence of a catalyst, wherein the catalyst is at least one selected from Copper, and Zinc supported on alumina.
In accordance with an embodiment of the present disclosure, the separation of the unreacted syngas and water in step is done by condensing, wherein the condensation is carried out at a temperature in the range of 20 °C to 50 °C and at a pressure in the range of 40 barA to 80 barA.
In the ninth step, the crude methanol is distilled to obtain the desired form of methanol.
In accordance with the present disclosure, the distillation of crude methanol is for separating dissolved gases and low and high boiling impurities including moisture at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA
In accordance with the present disclosure, the separated unreacted syngas is recirculated back to the inlet of at least one methanol synthesis unit after removal of crude methanol and the excess part of the unreacted syngas is purged out from the system to flare or is passed to a combustor to generate utilities like steam.
In another aspect, the present disclosure provides a system for the preparation of methanol from coal, the system (1000) comprises
i. at least one fluidized bed gasification unit (100), configured to receive a coal, super-heated steam, and oxygen and further configured to gasify the coal at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. at least one crude syngas cooling unit (200) and at least one particle separation unit (300) in fluid communication with the at least one fluidized bed gasification unit (100), configured for cooling and filtering the crude syngas to obtain a partially refined syngas (PRS);
iii. at least one condenser cum washing unit (400) in fluid communication with the at least one particle separation unit (300), configured to receive the partially refined syngas (PRS), and further configured to separate moisture partially to obtain a moisture-deficient partially refined syngas (MDPRS);
iv. at least one gas cleanup unit (500) in fluid communication with the at least one condenser cum washing unit (400), configured to receive the moisture-deficient partially refined syngas (MDPRS), and further clean to obtain a partially cleaned syngas (PCS); wherein the gas cleanup unit (500) is at least one selected from a tar removal unit, an acid washing unit, and a primary guard bed unit;
v. at least one water-gas shift reactor unit (600) in fluid communication with the at least one gas cleanup unit (500), configured to receive the partially cleaned syngas (PCS), steam and at least one catalyst, followed by amine treatment using at least one amine-based acid gas removal unit (610) in fluid communication with the at least one water-gas shift reactor unit (600) to absorb carbon dioxide (CO2) and hydrogen sulphide (H2S) to obtain a partially purified syngas (PPS); at least one cooling unit is configured to receive the partially purified syngas (PPS) to cool at a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
vi. at least one compressor unit (700) in fluid communication with the at least one amine-based acid gas removal unit (610), configured to receive the cooled partially purified syngas and compress the cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain compressed partially purified syngas (CPPS);
vii. at least one secondary guard bed unit (800) in fluid communication with the at least one compressor unit (700), configured to receive the compressed partially purified syngas (CPPS), and remove trace sulfur impurities to obtain a compressed purified syngas (CPS);
viii. at least one methanol synthesis unit (900) in fluid communication with the at least one secondary guard bed unit (800), configured to receive the compressed purified syngas (CPS) and synthesize a product mixture of crude methanol, water, and an unreacted syngas;
ix. at least one crude methanol separation unit (910) in fluid communication with the at least one methanol synthesis unit (900), configured to receive the product mixture and separate the unreacted syngas and water to produce crude methanol; and
x. at least one methanol distillation unit (920) in fluid communication with the at least one crude methanol separation unit (910), configured to receive the crude methanol and separate dissolved gases and impurities to obtain methanol.
The system (1000), of the present disclosure will now be described with reference to Figure 1. Figure 1 illustrates a schematic diagram of a system for the preparation of methanol from coal, in accordance with an embodiment of the present disclosure.
The preferred embodiment does not limit the scope and ambit of the present disclosure.
In the system (1000) illustrated in Figure 1, at least one fluidized bed gasification unit (100), is configured to receive coal, super-heated steam, and oxygen and gasify the coal at a first predetermined temperature and at a first predetermined pressure to obtain crude syngas.
In accordance with the embodiments of the present disclosure, the system (1000) comprises at least one coal crushing and feeding unit (10), upstream of the fluidized bed gasification unit (100). The coal crushing and feeding unit (10) is configured for crushing coal to a particle size in the range of 0.1 mm to 8 mm and further feeding the crushed coal particles to at least one fluidized bed gasification unit (100).
In accordance with the embodiments of the present disclosure, the coal crushing and feeding unit (10) comprises coal crushers, screening units, belt and bucket type conveyors, coal hoppers, and a coal metering unit with coal feeders.
In accordance with the embodiments of the present disclosure, coal hoppers are single or multiple lock hopper systems comprising at least two hoppers working in tandem to continuously supply the coal to the gasifier; wherein the coal is metered and fed using coal feeders that are volumetrically pre-calibrated for specific type of coal.
In accordance with the embodiments of the present disclosure, the fluidized bed gasification unit (100) comprises crushed refractory-type bed material or coal ash.
In the system (1000), at least crude syngas cooling unit (200) and at least one particle separation unit (300) are in fluid communication with the at least one fluidized bed gasification unit (100). The crude syngas cooling unit (200) is configured for cooling the crude syngas to a temperature in the range of 180 °C to 300 °C. The particle separation unit (300) is configured to filter the crude syngas to obtain partially refined syngas (PRS).
In accordance with the embodiments of the present disclosure, the crude syngas cooling unit (200) is a vertical-design cooling unit with single or multiple passes.
In accordance with the embodiments of the present disclosure, the particle separation unit (300) comprises at least one cyclone separator, one ceramic candle filter or bag filter. The filter unit is used to remove dust.
In the system (1000), at least one condenser cum washing unit (400) is in fluid communication with the at least one particle separation unit (300), configured to receive the partially refined syngas, and separate moisture to obtain a moisture-deficient partially cleaned syngas (MDPRS).
In accordance with the embodiments of the present disclosure, the condenser cum washing unit (400) comprises at least one indirect horizontal or vertical condenser and/or direct quench and condensing type washing unit which is at least one selected from the group consisting of a venturi scrubber, single or multi-stage open or packed bed towers utilizing water.
In the system, at least one gas cleanup unit (500) in fluid communication with at least one condenser cum washing unit (400), and is configured to receive the moisture-deficient partially cleaned syngas (MDPRS), and further clean to obtain partially cleaned syngas (PCS).
In accordance with the embodiments of the present disclosure, the gas cleanup unit (500) comprises a tar removal unit, an acid washing unit, and a primary guard bed unit. The primary guard bed unit contains at least one catalyst to remove fouling agents, the fouling agents include, metals, organometallic compounds, and corrosion products.
Further, the tar removal unit and acid washing unit is at least one selected from the group consisting of a single or multi-stage open or packed bed towers utilizing water and/or organic or hydrocarbon oil as scrubbing mediums.
In the system, at least one water-gas shift reactor unit (600) having at least one catalyst, is in fluid communication with at least one gas cleanup unit (500), configured to receive partially cleaned syngas (PCS), steam, and at least one catalyst, followed by amine treatment using at least one amine-based acid gas removal unit (610) to absorb the carbon dioxide (CO2) and hydrogen sulphide (H2S) to obtain a partially purified syngas.
In accordance with the embodiments of the present disclosure, the amine-based acid gas removal unit (610) comprises at least one amine absorber column and at least one amine regeneration column for regeneration of the amine in a closed-loop circuit by using steam.
In the system, at least one compressing unit (700) is in fluid communication with at least one amine-based acid gas removal unit (610), configured to receive and react the partially purified syngas and compress the partially purified syngas (PPS) to a pressure in the range of 40 bar to 80 bar to obtain compressed partially purified syngas (CPPS).
In the system, at least one secondary guard bed unit (800) is in fluid communication with at least one compressor unit, configured to receive the compressed syngas, and remove trace sulfur impurities to obtain compressed purified syngas (CPS).
In accordance with an embodiment of the present disclosure, the primary guard bed unit comprises multiple packed bed guard beds operating at a temperature in the range of 120°C to 250 °C.
In the system, at least one methanol synthesis unit (900) is in fluid communication with at least one secondary guard bed unit (800), configured to receive the compressed purified syngas (CPS) and synthesize a product mixture containing crude methanol, water, and unreacted syngas.
In accordance with the embodiments of the present disclosure, the methanol synthesis unit (900) comprises a feed heater, a reactor with a pelleted catalyst bed, and a product cooler.
In the system, at least one crude methanol separation unit (910) in fluid communication with at least one methanol synthesis unit (900) is configured to receive the product mixture and separate the unreacted syngas and water to produce crude methanol.
In the system, at least one methanol distillation unit (920) in fluid communication with at least one crude methanol separation unit (910), is configured to receive the crude methanol and separate dissolved gases and impurities to obtain methanol of the desired specification.
In accordance with the embodiments of the present disclosure, the crude methanol separation unit (910) comprises at least one condensing unit and at least one gas liquid separation unit in fluid communication with at least one methanol synthesis unit (900), configured to receive the product mixture and condense to separate the unreacted syngas and obtain the crude methanol comprising dissolved gases and impurities.
At least one distillation unit (920) in fluid communication with the crude methanol separation unit (910), configured to distill the crude methanol containing dissolved gases and the impurities at a predetermined temperature and a predetermined pressure to obtain methanol, wherein the impurities are low and high boiling impurities like moisture.
In accordance with an embodiment of the present disclosure, the distillation of the crude methanol containing dissolved gases and the impurities is carried out at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA to obtain methanol.
In accordance with the embodiments of the present disclosure, the system (1000) comprises at least one steam generation unit for the generation of steam using heat rejected from at least one crude syngas cooling unit and using heat rejected from the methanol synthesis unit.
In accordance with the embodiments of the present disclosure, the system (1000) comprises at least one methanol purification unit in fluid communication with the methanol distillation unit (920), which is configured to obtain methanol of the required specifications.
In accordance with the embodiments of the present disclosure, the system (1000) comprises at least one methanol storage unit.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to an industrial/commercial scale and the results obtained can be extrapolated to an industrial scale.
Experimental details:
Example 1
Preparation of methanol from coal in accordance with the present disclosure:
200 kg/hr of G11 type Indian coal having 35wt% ash containing 29wt% fixed carbon, 180 kg/hr of super-heated steam and 105 kg/hr of oxygen were fed to a fluidized bed gasifier, and the coal was gasified at a temperature of 960 °C to 980 °C and at a pressure of 4.5 - 5.4 barA to obtain crude syngas. The crude syngas was then cooled to a temperature of 180 °C to 220°C, and filtered using two cyclones and a dust candle filter placed in series to obtain partially refined syngas (PRS) having a moisture content of 45% to 50%. Moisture was removed from the partially refined syngas at 45 °C to obtain moisture-deficient partially refined syngas (MDPRS) with 1.84vol% moisture content, followed by cleaning to remove tar, acid washing, and removal fouling agents to obtain partially cleaned syngas (PCS). The partially cleaned syngas (PCS) was then fed to a water gas shift reactor along with 26.8 kg/hr steam consisting of sour shift catalyst to obtain a reaction product, which was then amine treated to obtain partially purified syngas (PPS). The partially purified syngas (PPS) was then compressed at 73 barA to obtain compressed partially purified syngas (CPPS). The compressed partially purified syngas (CPPS) was then passed through a primary guard bed unit to remove trace sulfur impurities to obtain a compressed purified syngas (CPS). The compressed purified syngas (CPS) then fed to a methanol synthesis unit for synthesizing a product mixture comprising crude methanol, water and unreacted syngas. Thereafter, the product gas was condensed to 40°C and distilled in final refining column at 1.2 barA and 95 °C to obtain 42 kg/hr of pure methanol.
The obtained methanol had a purity of 99.85%.
Example 2
Preparation of methanol from coal in accordance with the present disclosure:
248 kg/hr of G14 type Indian coal having 52 wt% ash and 23 wt% fixed carbon, 210 kg/hr of super-heated steam and 120 kg/hr of oxygen were fed to a fluidized bed gasifier and the coal was gasified at a temperature of 960 °C to 980 °C and at a pressure of 4.5-5.5 barA to obtain crude syngas. The crude syngas was then cooled to a temperature of 210°C, and filtered using a cyclone separator and a dust filter to obtain partially refined syngas (PRS) having a moisture content of 55%. Moisture was removed from the partially refined syngas (PRS) at 47 °C to obtain moisture-deficient partially refined syngas (MDPRS) with 2.07vol% moisture content, followed by cleaning to remove tar, acid washing, and removal fouling agents to obtain partially cleaned syngas (PCS) to obtain partially cleaned syngas (PCS). The partially cleaned syngas (PCS) was then fed to a water gas shift reactor along with 21.3 kg/hr steam consisting of sour shift catalyst to obtain a reaction product, which was then amine treated to obtain partially purified syngas (PPS). The partially purified syngas (PPS) was then compressed at 73 barA bar to obtain compressed partially purified syngas. The compressed partially purified syngas was then passed through a primary guard bed unit to remove trace sulfur impurities to obtain a compressed purified syngas (CPS), followed by feeding to a methanol synthesis unit for synthesizing a product mixture comprising crude methanol, water and unreacted syngas. Thereafter, the product gas was condensed to 45 °C and distilled at 1.15 bar and 93 °C to obtain 40 kg of pure methanol.
The obtained methanol had a purity of 99.78%.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the system for the preparation of methanol from coal, wherein the system, that:
• able to handle coal with different and higher ash content;
• improves coal-to-methanol conversion efficiency; and
• is easy to use.
and
the method for the preparation of methanol from coal, that;
• is simple to perform;
• is reliable, and cost-effective;
• improves coal-to-methanol conversion efficiency; and
• produces clean syngas suitable for chemical production.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

, Claims:WE CLAIM:
1. A method for the preparation of methanol from coal, said method comprising the following steps:
i. gasifying coal in at least one fluidized bed gasification unit by treating a mixture of coal, super-heated steam, and oxygen at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. cooling and filtering said crude syngas to obtain a partially refined syngas (PRS);
iii. removing moisture partially from said partially refined syngas (PRS) to obtain a moisture-deficient partially refined syngas (MDPRS), followed by cleaning to obtain partially cleaned syngas (PCS);
iv. reacting said partially cleaned syngas (PCS) with a steam and a catalyst in a predetermined ratio at a second predetermined temperature and at a second predetermined pressure, followed by amine treatment to obtain partially purified syngas (PPS) and cooling said partially purified syngas (PPS) to a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
v. compressing said cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS);
vi. removing trace sulfur impurities from said compressed partially purified syngas (CPPS) to obtain compressed purified syngas (CPS);
vii. synthesizing a product mixture of crude methanol, water, and unreacted syngas from said compressed purified syngas (CPS);
viii. separating said unreacted syngas and water from said product mixture to obtain a crude methanol; wherein a separated unreacted syngas is recycled back to at least one methanol synthesis unit; and
ix. distilling said crude methanol in at least one methanol distillation unit to obtain methanol.
2. The method as claimed in claim 1, wherein said coal is at least one selected from Indian coal, South African coal and Indonesian coal, wherein said coal has an ash content of up to 52 mass%; and wherein said Indian coal is selected from grades G-1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G12, G13, G14, G-15 and combinations thereof and wherein said South African coal is selected from grades RB-1, RB-2, RB-3 and combinations thereof.
3. The method as claimed in claim 1, wherein said coal has a particle size in the range of 0.1 mm to 8 mm.
4. The method as claimed in claim 1, wherein a ratio of said super-heated steam to said coal is in the range of 0.70 to 1.0 and a ratio of said oxygen to said coal is in the range of 0.35 to 0.50.
5. The method as claimed in claim 1, wherein said first predetermined temperature is in the range of 900 °C to 1050 °C and said first predetermined pressure is in the range of 1.1 barA to 8 barA.
6. The method as claimed in claim 1, wherein said cooling of said crude syngas is done in a syngas cooling system, wherein said crude syngas is cooled to a temperature in the range of 180 °C to 300 °C.
7. The method as claimed in claim 1, wherein during filtration of said crude syngas in step (ii), fly ash is separated by using cyclone separation to separate coarse fly ash particles, followed by using at least one candle filter to separate fine fly ash particles having a size less than 1 micron.
8. The method as claimed in claim 1, wherein said cleaning in step (iii) is performed at a temperature in the range of 40 °C to 55 °C.
9. The method as claimed in claim 1, wherein in said cleaning in step (iii), said moisture-deficient partially refined syngas (MDPRS) is treated to remove the impurities, sequentially followed by removal of tar containing heavy and light aromatics, acid washing, and removal of fouling agents, wherein said fouling agents include metals, organo-metallic compounds, and corrosion products.
10. The method as claimed in claim 1, wherein said molar ratio of said steam to said carbon monoxide present in said partially cleaned syngas (PCS) is in the range of 1.01 to 1.6.
11. The method as claimed in claim 1, wherein said second predetermined temperature is in the range of 260 °C to 370 °C and said second predetermined pressure is in the range of 1.1 barA to 8 barA.
12. The method as claimed in claim 1, wherein said amine treatment comprises the steps of removal of acid gases; and absorption of carbon dioxide (CO2) and hydrogen sulphide (H2S) at a pressure in the range of 1.1 barA to 8 barA; at a temperature in the range of 45 °C to 60 °C.
13. The method as claimed in claim 1, wherein said trace sulfur impurities are removed from said compressed partially purified syngas (CPPS) using at least one catalyst selected from organic sulfur removal catalysts, inorganic sulfur removal catalysts and metal carbonyl removal catalyst.
14. The method as claimed in claim 1, wherein said synthesis of said product mixture in step (vii) comprises heating said compressed purified syngas (CPS) at a temperature in the range of 205 °C to 220 °C to obtain a heated compressed purified syngas (HCPS), and reacting said heated compressed purified syngas (HCPS) at a pressure in the range of 50 barA to 80 barA and at a temperature of less than 280 °C in the presence of a catalyst, wherein said catalyst is at least one selected from Copper, and Zinc supported on alumina.
15. The method as claimed in claim 1, wherein said separation of said unreacted syngas and water in step (viii) is done by condensing, wherein said condensation is carried out at a temperature in the range of 20 °C to 50 °C and at a pressure in the range of 40 barA to 80 barA.
16. The method as claimed in claim 1, wherein in step (ix), said distillation of crude methanol is carried out for separating dissolved gases and low and high boiling impurities including moisture at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA.
17. The method step as claimed in claim 1, wherein said separated unreacted syngas is recirculated back to the inlet of at least one methanol synthesis unit after removal of crude methanol and the excess part of said unreacted syngas is purged out from said system to flare or is passed to a combustor to generate utilities like steam.
18. A system (1000) for the preparation of methanol from coal, said system (1000) comprises:
i. at least one fluidized bed gasification unit (100), configured to receive a coal, super-heated steam, and oxygen and further configured to gasify said coal at a first predetermined temperature and at a first predetermined pressure to obtain a crude syngas;
ii. at least one crude syngas cooling unit (200) and at least one particle separation unit (300) in fluid communication with said at least one fluidized bed gasification unit (100), configured for cooling and filtering said crude syngas to obtain a partially refined syngas (PRS);
iii. at least one condenser cum washing unit (400) in fluid communication with said at least one particle separation unit (300), configured to receive said partially refined syngas (PRS), and further configured to separate moisture partially to obtain a moisture-deficient partially refined syngas (MDPRS);
iv. at least one gas cleanup unit (500) in fluid communication with said at least one condenser cum washing unit (400), configured to receive said moisture-deficient partially refined syngas (MDPRS), and further clean to obtain a partially cleaned syngas (PCS), wherein said gas cleanup unit (500) is at least one selected from a tar removal unit, an acid washing unit, and a primary guard bed unit;
v. at least one water-gas shift reactor unit (600) in fluid communication with said at least one gas cleanup unit (500), configured to receive and react said partially cleaned syngas (PCS), steam and at least one catalyst, followed by amine treatment using at least one amine-based acid gas removal unit (610) in fluid communication with said at least one water-gas shift reactor unit (600) to absorb carbon dioxide (CO2) and hydrogen sulphide (H2S) to obtain a partially purified syngas (PPS); at least one cooling unit is configured to receive said partially purified syngas (PPS) to cool at a temperature in the range of 5 °C to 15 °C to obtain a cooled partially purified syngas;
vi. at least one compressor unit (700) in fluid communication with said at least one amine-based acid gas removal unit (610), configured to receive said cooled partially purified syngas and compress said cooled partially purified syngas to a pressure in the range of 40 barA to 80 barA to obtain a compressed partially purified syngas (CPPS);
vii. at least one secondary guard bed unit (800) in fluid communication with said at least one compressor unit (700), configured to receive said compressed partially purified syngas (CPPS), and remove trace sulfur impurities to obtain a compressed purified syngas (CPS);
viii. at least one methanol synthesis unit (900) in fluid communication with said at least one secondary guard bed unit (800), configured to receive said compressed purified syngas (CPS) and synthesize a product mixture of crude methanol, water, and an unreacted syngas;
ix. at least one crude methanol separation unit (910) in fluid communication with said at least one methanol synthesis unit (900), configured to receive said product mixture and separate said unreacted syngas and water to produce crude methanol; and
x. at least one methanol distillation unit (920) in fluid communication with said at least one crude methanol separation unit (910), configured to receive said crude methanol and separate dissolved gases and impurities to obtain methanol.
19. The system (1000) as claimed in claim 18, wherein said system comprises at least one coal crushing and feeding unit (10), configured for crushing coal to a particle size in the range of 0.1 mm to 8 mm and further feeding said crushed coal particles to at least one fluidized bed gasification unit (100).
20. The system (1000) as claimed in claim 19, wherein said coal crushing and feeding unit (10) comprises coal crushers, screening units, belt and bucket type conveyors, coal hoppers, and a coal metering unit with coal feeders.
21. The system (1000) as claimed in claim 20, wherein said coal hoppers are single or multiple lock hopper systems comprising at least two hoppers working in tandem to continuously supply the coal to the gasifier; wherein said coal is metered and fed by using coal feeders that are volumetrically pre-calibrated for specific type of coal.
22. The system (1000) as claimed in claim 18, wherein said fluidized bed gasification unit (100) comprises crushed refractory type bed material.
23. The system (1000) as claimed in claim 18, wherein said crude syngas cooling unit (200) is a vertical design cooling unit with single or multiple passes.
24. The system (1000) as claimed in claim 18, wherein said condenser cum washing unit (400) is at least one selected from an indirect horizontal or vertical condenser and or direct quench and condensing type washing unit which is at least one selected from the group consisting of a venturi scrubber, and single or multi-stage open or packed bed towers.
25. The system (1000) as claimed in claim 18, wherein said tar removal unit and said acid washing unit is at least one selected from the group consisting of a single or multi-stage open or packed bed towers.
26. The system (1000) as claimed in claim 18, wherein said amine-based acid gas removal unit (610) comprises at least one amine absorber column and at least one amine regeneration column for regeneration of said amine in a closed-loop circuit by using steam.
27. The system (1000) as claimed in claim 18, wherein said secondary guard bed unit (800) comprises multiple packed bed guard beds operating at a temperature in the range of 120 °C to 250 °C.
28. The system (1000) as claimed in claim 18, wherein said methanol synthesis unit (900) comprises a feed heater, a reactor with a pelleted catalyst bed, and a product cooler.
29. The system (1000) as claimed in claim 18, wherein said crude methanol separation system (910) comprises at least one condensing unit in fluid communication with at least one methanol synthesis unit (900), configured to receive said product mixture and condense to separate said unreacted syngas to obtain a crude methanol comprising dissolved gases and impurities.
30. The system (1000) as claimed in claims 18, wherein said at least one distillation unit (920) is configured to distill said crude methanol comprising dissolved gases and impurities at a temperature in the range of 65 °C to 120 °C and at a pressure in the range of 1.1 barA to 2 barA to obtain methanol.
31. The system (1000) as claimed in claim 18, wherein said system comprises at least one steam generation unit for the generation of steam by using heat rejected from said crude syngas cooling unit (200) and from said methanol synthesis unit (900).
32. The system (1000) as claimed in claim 18, wherein said system comprises at least one methanol purification unit in fluid communication with said methanol distillation unit (920), is configured to obtain methanol of the required specification.
33. The system (1000) as claimed in claim 18, wherein said system comprises at least one methanol storage unit.
Dated this 11th Day of May, 2024

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K. DEWAN & CO.
Authorized Agent of Applicant