Claims:1. A modular system (200) for generating hydrogen from biomass, the modular system (200) comprising:
a gasifier (102) adapted to receive biomass and convert the received biomass into syngas, wherein the syngas is treated to remove any or a combination of H2S, HCl, HCN, and Ammonia, and Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream;
a static mixer (120) configured to receive and mix the acid-alkali free and de-oxygenated gas stream with steam to form a gas-steam mixture;
a high-temperature shift (HTS) reactor (122) and a low-temperature shift (LTS) reactor (126) fluidically coupled to the static mixer (120), wherein the HTS (122) reactor and the LTS (126) reactor are configured to facilitate a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2);
a CO2 remover (136, 142) fluidically coupled to the HTS (122) and LTS (126), and configured to remove CO2 from the gas stream to provide CO2 free gas stream; and
a hydrogen separator (138) selected from any or a combination of a pressure swing adsorber (PSA), and a vacuum pressure swing adsorber (VPSA), the hydrogen separator (138) fluidically coupled to the CO2 remover and configured to separate hydrogen from the CO2-free gas stream to provide the H2 gas.
2. The modular system (200) as claimed in claim 1, wherein the modular system (200) comprises:
an acid-alkali scrubber (104) comprising an acid scrubber and a water scrubber configured at an output side of the gasifier (102) and adapted to remove HCl, HCN, and Ammonia from the syngas, and reduce the level of the H2S in the syngas to 10 ppm;
a compressor (108) and a first preheater (112-1) configured to compress and heat the acid-alkali free gas to 7 bar pressure and 225°C temperature;
an H2S absorber (116) comprising a Zinc Oxide (ZnO) bed adapted to reduce the level of the H2S in the heated gas to 0.1 ppm; and
a de-oxygenator (114) comprising a palladium-based catalyst, the de-oxygenator (114) is configured to facilitate the reaction between H2 and O2, which results in complete consumption of O2 and generation of water vapor, thereby removing O2 present in the received gas stream and providing the de-oxygenated gas stream.
3. The modular system (200) as claimed in claim 2, wherein the modular system (200) comprises a second preheater (112-2) configured such that the de-oxygenator (114) and a hot air generator (118) are connected to an input side of the second preheater (112-2), and the static mixer (120) and the first preheater (112-1) are connected to an output side of the second preheater (112-2), wherein the second preheater (112-2) is configured to receive hot air from the hot air generator (118) and correspondingly increase the temperature of the acid-alkali free and de-oxygenated gas stream to 380-400°C.
4. The modular system (200) as claimed in claim 1, wherein a catalyst associated with the HTS (122) is activated using the heat of the process gas stream flowing therethrough, and a catalyst associated with the LTS (126) is activated using hydrogen.
5. The modular system (200) as claimed in claim 1, wherein the effluent gas generated by the PSA and/or the VPSA (138), upon separation of the H2, is used by the hot air generator to generate hot flue gas, and wherein the hot flue gas generated by the hot air generator (118) is used in any or a combination of the first preheater (112-1), the second preheater (112-2), a first HRSG (134-1), and a second HRSG (134-2) associated with the system (200), thereby providing improved thermal efficiency.
6. The modular system (200) as claimed in claim 1, wherein the modular system (200) comprises:
a cooler (128) and an intercooler (124) configured to receive water through a phase separator (132) and preheat and partially vaporize the received water; and
a first heat recovery steam generator (HRSG) (134-1) configured to receive and convert the preheated water into steam, and supply the steam to the static mixer (120) for mixing with the acid-alkali free and de-oxygenated gas and lower the temperature of the mixture to 300-330°C.
7. The modular system (200) as claimed in claim 6, wherein the temperature of the gas stream exiting the HTS (122) reactor is raised to 400°C and passed through the intercooler (124) to cool the gas to 190-200°C, and wherein the heat of the passing gas stream is used to preheat the water received from the phase separator (132) for the steam generation.
8. The modular system (200) as claimed in claim 7, wherein the cooled gas stream from the intercooler (124) is passed through the LTS (126) reactor and the cooler (128), which is further passed through a condenser (130) to condense water vapor present in the flowing gas stream, and wherein the phase separator (132) receives the gas stream having condensed water vapor from the condenser (130) and separates the condensed water from the gas stream to provide a moisture-free gas and resupply the separated water to the first HRSG (134-1) for steam generation.
9. The modular system (200) as claimed in claim 1, wherein the CO2 remover is an amine-based CO2 remover comprising a CO2 absorber (136), and a CO2 stripper (142), wherein
the CO2 absorber (136) is configured to absorb the CO2 from the gas stream using a counterflowing amine stream to remove CO2 and provide the CO2-free gas;
the CO2 rich amine exiting the CO2 absorber (136) gets heated in a cross-heat exchanger 140) and enters into the CO2 stripper (142) that strips the absorbed CO2 from the amine using steam to form a CO2-steam mixture, and
the CO2-steam mixture exits the CO2 stripper (142) and gets condensed in an overhead condenser (148) to generate water and separate the CO2, wherein the amine generated by the CO2 stripper (142) is supplied to the reboiler (146), and the amine is heated and purified using steam generated by the second HRSG (134-2) to obtain lean amine that is supplied back to the CO2 absorber (136).
10. The modular system (200) as claimed in claim 1, wherein the modular system (200) comprises:
a set of sensors (202) to monitor temperature and attributes of any or a combination of the biomass, the syngas, gas stream, the water, and the steam flowing through one or more components of the modular system (200);
a set of control valves (204) to control the flow of any or a combination of the biomass, the syngas, gas stream, the water, and the steam within the system (200); and
a control unit (206) in communication with the set of sensors (202), and the set of control valves (204), the control unit (206) configured to monitor and control the temperature, the attributes, and the flow of any or a combination of the biomass, the syngas, the gas stream, the water, and the steam within the modular system (200).
11. The modular system (200) as claimed in claim 1, wherein the hydrogen generated in the modular system (200) is used in fuel cells of a fuel cell vehicle.
12. A method (300) for generating hydrogen from biomass, the method comprising the steps of:
gasifying (302), by a gasifier (102), the biomass into syngas;
treating (304), by an acid-alkali scrubber (104), a ZnO-based H2S scrubber (116), and a de-oxygenator (114), the syngas to remove any or a combination of H2S, HCl, HCN, and Ammonia, and Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream;
mixing (306), in a static mixer (120), the acid-alkali free and de-oxygenated gas stream with steam to form a gas-steam mixture;
enabling (308), by a high-temperature shift (HTS) reactor (122) and a low-temperature shift (LTS) reactor (126), a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2);
passing (310), through a CO2 remover (136, 142), the gas stream to remove CO2 and provide CO2 free gas stream; and
passing (312), through a hydrogen separator (138) selected from any or a combination of a pressure swing adsorber (PSA), and a vacuum pressure swing adsorber (VPSA), the CO2-free gas stream to separate hydrogen from the CO2-free gas stream and provide the H2 gas.
13. The method (300) as claimed in claim 12, wherein the method (300) comprises the steps of activating a catalyst associated with the HTS (122) using the heat of the process gas stream flowing therethrough, and activating a catalyst associated with the LTS (126) using hydrogen.
14. The method (300) as claimed in claim 13, wherein the effluent gas generated by the PSA and/or the VPSA (138), upon separation of the H2, is used by the hot air generator (118) to generate hot flue gas, and wherein the hot flue gas generated by the hot air generator (118) is used effectively in the first preheater (112-1), the second preheater (112-2), the first HRSG (134-1), and the second HRSG (134-2), thereby providing improved thermal efficiency.
, Description:TECHNICAL FIELD
[0001] The present invention relates to the field of hydrogen generation, and in particular, relates to a simple, cost-effective, and efficient modular system and method for generating hydrogen from biomass.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Agricultural residue and municipal solid waste (MSW) are two significant sources of biomass in the country. Every year India generates 200+ million-ton waste biomass. Disposal of such biomass is a big challenge. Farmers mostly burn the residue in the fields, which aggravates the problem of pollution in the nearby areas. On the other hand, disposal of MSW is a bigger challenge for all metro and tier-1 cities in the country.
[0004] With the shortage of fossil fuel and the increasingly tight energy supply situation, the development of biomass energy has attracted great attention. Biomass energy has the characteristics of abundant resources, huge reserves, and is renewable in nature. Biomass power generation technology uses waste biomass resources such as straw to produce green power, which is of great significance for easing power supply shortages and ensuring energy security.
[0005] The currently developed biomass power generation technologies mainly include biomass direct combustion power generation and gasification power generation. Direct combustion power generation uses biomass as a boiler fuel to produce superheated steam by direct combustion of the biomass and realizes power production through steam turbines. However, the currently developed biomass-based power generation technologies cannot be used in automobiles, which are one of the major sources of pollution and carbon emission.
[0006] Renewable energy has gained its importance as an alternative source of energy due to the growing concern about the increase in pollution and its adverse impact on global climatic conditions. Though renewable electricity will play an important role in the decarbonization of the energy sector, certain sectors such as transportation and industrial applications will also depend on green Hydrogen for their decarbonization. For instance, in the transportation sector, the use of green Hydrogen as a fuel in hydrogen powered vehicles or fuel cell vehicles will be ideal, especially in the case of long-distance transportation. Further, hydrogen is also utlizied in the industry as it is widely used for refining petroleum, treating metals, steel production, producing fertilizer, ammonia production. Hydrogen is also used as a chemical reagent in the food industry for processing various food products. Use of green Hydrogen in the said applications will help in the decarbonization of these industrial sectors.
[0007] Electric vehicles are also one such alternative, but, electric vehicles are constrained by their range and charging time when it comes to long-distance travel.
[0008] Utilizing biomass for green Hydrogen generation, in an efficient, and cost-effective way, will not only address the problem of disposal of biomass but will provide us with clean Hydrogen fuel. Thus, there is a need for a simple, cost-effective, efficient, and environmentally-friendly system and method, which generates clean hydrogen from biomass in a carbon-neutral way.

OBJECTS OF THE INVENTION
[0009] An object of the present invention is to provide a modular system and method, which generates clean hydrogen from biomass.
[0010] Yet another object of the present invention is to address the disposal of biomass and the generation of clean and industrial-grade hydrogen fuel.
[0011] Another object of the present invention is to reduce the carbon footprint while generating high purity hydrogen gas.
[0012] Yet another object of the present invention is to provide a system and method that utilize biomass for the generation of hydrogen fuel, in an efficient, cost-effective and environmentally friendly way.
[0013] Yet another object of the present invention is to provide a modular system and method for generating clean hydrogen from biomass, which reutilizes the heat and flue gas generated during the process in a carbon-neutral way.
[0014] Yet another object of the present invention is to provide an automated control mechanism for the hydrogen generation system and method, which automatically, remotely, and efficiently monitors and controls the overall hydrogen generation operation.
[0015] Yet another object of the present invention is to provide a modular system and method for the generation of high purity hydrogen which can be used for various industrial and transportation/automotive applications, such as in fuel cells of fuel cell-based vehicles, in hydrogen-powered vehicles, and other modes of transport requiring hydrogen.

SUMMARY
[0016] The present invention relates to a simple, cost-effective, efficient, and environmentally-friendly, modular system and method, which addresses the disposal of biomass as well as the generation of clean and industrial-grade hydrogen fuel, by generating clean hydrogen from biomass in a carbon-neutral way.
[0017] According to an aspect, the modular system and method of the present disclosure comprises of a gasifier, an acid-alkali scrubber, a de-oxygenator, a static mixer, a high-temperature shift (HTS) reactor and a low-temperature shift (LTS) reactors, a CO2 remover, and a hydrogen separator selected from a pressure swing adsorber (PSA), or a vacuum pressure swing adsorber (VPSA). The modular system and method further involve preheaters, cooler, intercooler, compressor, phase separator, condenser, and two heat recovery steam generators (HRSG). The biomass is fed to the gasifier, where the biomass undergoes the process of gasification and is converted into syngas. The syngas is then passed through the acid-alkali scrubber to remove H2S, HCl, HCN, and Ammonia, present in the syngas. The gas (syngas) is then compressed to the pressure of 7 bar for further processing. The gas is then heated and passed through an H2S removal bed comprising ZnO to remove any traces of H2S present in the gas. Further, the de-oxygenator comprising a palladium-based catalyst facilitates the reaction between H2 and O2, which results in complete consumption of O2 and generation of water vapor, thereby removing O2 present in the gas to provide an acid-alkali free and de-oxygenated gas stream.
[0018] The acid-alkali-free and de-oxygenated gas stream is then heated using the preheater that gets heated using a hot air generator. The heated gas stream then enters the static mixer where it gets mixed with steam. In an aspect, water enters the system via the phase separator, where it picks up the heat as it passes through the cooler followed by the intercooler and gets preheated and partially vaporised. The preheated water then enters the first HRSG where it gets converted into steam. This steam generated in the first HRSG enters the static mixer where it gets mixed with the gas stream.
[0019] The HTS and LTS are water gas shift reactors where CO from the gas stream of the gas-steam mixture reacts with steam to produce CO2 and Hydrogen. The temperature of the gas exiting HTS is elevated due to exothermic reaction. The gas then passes through the intercooler, where it is cooled to 190-200°C. In an aspect, the heat energy present in the gas is efficiently used to preheat the incoming process water. The gas then passes through the LTS for further reaction and then passes through the cooler. The gas then passes through the condenser where the excess water vapor in the gas gets condensed. The gas then flows into the phase separator, where residual water droplets are separated from the gas stream to provide moisture-free gas. Accordingly, the water generated is recycled in the overall process.
[0020] Conventionally, in the HTS, heating of the catalyst to achieve the shift temperature is done by using heated Nitrogen at the beginning of the process. However, with the method of the present invention, the catalyst is heated directly by using the generated process gas and steam mixture in the HTS, thereby, making the system efficient and simplified. The design ensures that no undersidered reactions takes place in the reactor. Further, the LTS is activated offline using hydrogen.
[0021] The moisture-free gas is then processed for CO2 removal. The CO2 remover is an amine-based CO2 remover system comprising a CO2 absorber and a CO2 stripper. The CO2 absorber is configured to absorb the CO2 from the gas stream using a counterflowing amine stream to remove CO2 and provide the CO2-free gas. Further, the CO2-rich amine exiting the CO2 absorber gets heated in a cross-heat exchanger and enters into the CO2 stripper that strips the absorbed CO2 from the amine using steam to form a CO2-steam mixture. Furthermore, the CO2-steam mixture exits the CO2 stripper and gets condensed in an overhead condenser to generate water and separate the CO2. This CO2 can further be utilized for various industrial applications. The amine generated by the CO2 stripper is supplied to a reboiler, and the amine is heated and purified further using steam generated by a second HRSG to obtain lean amine that is supplied back to the CO2 absorber.
[0022] The CO2-free gas coming out of the CO2 absorber then enters the PSA and/or the VPSA, which separates hydrogen from the CO2-free gas stream to provide the H2 gas. The H2 gas generated with the system and method of the present invention is of high purity, between 95-99%, and hence can be used for various applications. The effluent of the PSA is used in hot air generator for thermal application. Those skilled in the art would appreciate that the product of the hot air generator is efficiently utilized for heating the process gas and also for steam generation. The flue gas is utilized efficiently in the heat exchangers, preheaters, and HRSGs by controlling and using the various temperature sensors, temperature control valves and bypass lines provided across these heat exchangers, thereby optimizing the requirement of flue gas to meet the thermal demand and reducing the carbon footprint.
[0023] In another aspect, the modular system comprises a control unit in communication with the sensors, and the control valves associated with the system. The control unit measures, monitors and controls the temperature, the attributes, and the flow of any or a combination of the biomass, the syngas, the gas stream, the water, and the steam within the system, and also controls the overall operation of the system, thereby making the system and method automated and efficient.
[0024] Accordingly, the proposed modular system and method generates hydrogen for green energy applications, in an efficient, and cost-effective way, also addresses the problem of disposal of biomass, by providing a simple, cost-effective, efficient, and environmentally-friendly system and method, which generates clean and high purity hydrogen from biomass in a carbon-neutral way. Besides, the control unit enables automated and efficient operation of the system.

BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0026] FIG. 1 illustrates an exemplary block diagram of a hydrogen generator unit of the proposed modular system for generating hydrogen from biomass, according to an embodiment of the present invention.
[0027] FIG. 2 illustrates an exemplary block diagram of the proposed modular system comprising a control unit connected to the hydrogen generator for automated operation of the proposed system, according to an embodiment of the present invention.
[0028] FIG. 3 illustrates exemplary steps involved in the proposed method for generating high purity hydrogen from biomass, according to an embodiment of the present invention.

DETAILED DESCRIPTION
[0029] The present invention relates to a simple, cost-effective, efficient, and environmentally-friendly, modular system and method, which addresses the disposal of biomass as well as the generation of clean and industrial-grade hydrogen fuel, by generating clean hydrogen from biomass in a carbon-neutral way. According to an aspect, the proposed system comprises a gasifier adapted to receive varities of biomass and convert the received biomass into syngas. Further, the syngas is treated to remove any or a combination of H2S, HCl, HCN, Ammonia, and Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream. The system further comprises a static mixer configured to receive and mix the acid-alkali-free and de-oxygenated gas stream with steam to form a gas-steam mixture. The system further comprises a high-temperature shift (HTS) reactor and a low-temperature shift (LTS) reactor fluidically coupled to the static mixer, wherein the HTS reactor and the LTS reactor are configured to facilitate a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2). The system further comprises a CO2 remover fluidically coupled to the HTS and LTS and configured to remove CO2 from the gas stream to provide CO2 free gas stream and pure CO2 stream. The system further comprises a hydrogen separator selected from any or a combination of a pressure swing adsorber (PSA), and a vacuum pressure swing adsorber (VPSA). The hydrogen separator is fluidically coupled to the CO2 remover and configured to separate hydrogen from the CO2-free gas stream to provide the H2 gas.
[0030] In an embodiment, the system comprises an acid-alkali scrubber comprising an acid scrubber and a water scrubber configured at an output side of the gasifier and adapted to remove HCl, HCN, and Ammonia from the syngas, and reduce the level of the H2S in the syngas to 10 ppm. The system further comprises a compressor and a first preheater configured to compress and heat the acid-alkali free gas to 7 bar pressure and 225°C temperature. The system further comprises an H2S absorber comprising a ZnO bed installed to reduce the level of the H2S in the gas to 0.1 ppm. The system comprises a de-oxygenator comprising a palladium-based catalyst. The deoxygenartor is configured to facilitate the reaction between H2 and O2 resulting in complete consumption of O2 and generation of water vapor, thereby removing O2 present in the received gas and to provide the de-oxygenated gas stream.
[0031] In an embodiment, the system comprises a second preheater configured such that the H2S absorber and a hot air generator are connected to an input side of the second preheater, and the static mixer and the first preheater are connected to an output side of the second preheater. The second preheater is configured to receive hot air from the hot air generator and correspondingly increase the temperature of the acid-alkali free and de-oxygenated gas stream to 380-400°C.
[0032] In an embodiment, a catalyst associated with the HTS reactor is activated using the heat of the process gas stream flowing therethrough, and a catalyst associated with the LTS reactor is activated offline using hydrogen.
[0033] In an embodiment, the effluent generated by the PSA and/or the VPSA, upon separation of the H2, is used by the hot air generator to generate hot flue gas. Further, the hot flue gas generated by the hot air generator is used effectively in the first preheater, the second preheater, the first HRSG, and the second HRSG associated with the system, thereby providing improved thermal efficiency.
[0034] In an embodiment, the system comprises a cooler and an intercooler configured to receive water through a phase separator and preheat the received water, and a first heat recovery steam generator (HRSG) configured to receive and convert the preheated water into steam, and supply the steam to the static mixer for mixing with the acid-alkali free and de-oxygenated gas and lower the temperature of the mixture to 300-330°C.
[0035] In an embodiment, the temperature of the gas stream exiting the HTS reactor is raised to 400°C due to exothermic reaction in the HTS and passed through the intercooler to cool the gas to 190-200°C. The heat of the passing gas stream is used to preheat the water received from the phase separator for steam generation.
[0036] In an embodiment, the cooled gas stream from the intercooler is passed through the LTS reactor and the cooler, which is further passed through a condenser to condense water vapor present in the flowing gas stream. The phase separator receives the gas stream and separates any residual water droplets from the gas to provide a moisture-free gas and resupply the separated water to the first HRSG for steam generation.
[0037] In an embodiment, the CO2 remover is an amine-based CO2 remover system comprising a CO2 absorber, and a CO2 stripper. The CO2 absorber is configured to absorb the CO2 from the gas stream, which also contains nitrogen and a little amount of methane, using a counterflowing amine stream to remove CO2 and provide the CO2-free gas. Further, the CO2-rich amine exiting the CO2 absorber gets heated in a cross-heat exchanger and enters into the CO2 stripper that strips the absorbed CO2 from the amine using steam to form a CO2-steam mixture. Furthermore, the CO2-steam mixture exits the CO2 stripper and gets condensed in an overhead condenser to generate water and sepaarte the CO2. This CO2 can further be utilized for various industrial applications. The amine geenarted by the CO2 stripper is supplied to the reboiler and the amine is heated and purified further using steam generated by the second HRSG to obtain lean amine that is supplied back to the CO2 absorber.
[0038] In an embodiment, the system comprises a set of sensors to measure and monitor the temperature and attributes of any or a combination of the biomass, the syngas, gas stream, the water, and the steam flowing through one or more components of the system. The system further comprises a set of control valves to control the flow of any or a combination of the biomass, the syngas, gas stream, the water, and the steam within the system. Further, the system comprises a control unit in communication with the set of sensors, and the set of control valves. The control unit is configured to monitor and control the temperature, the attributes, and the flow of any or a combination of the biomass, the syngas, the gas stream, the water, and the steam within the system.
[0039] According to another aspect, the present disclosure elaborates upon a method for generating hydrogen from biomass. The method comprising the steps of gasifying, by a gasifier, the biomass into syngas, followed by treating, by an acid-alkali scrubber and a de-oxygenator, the syngas to remove any or a combination of H2S, HCl, HCN, and Ammonia, and Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream. The method further comprises the step of mixing, in a static mixer, the acid-alkali free and de-oxygenated gas stream with steam to form a gas-steam mixture, followed by a step of enabling, by a high-temperature shift (HTS) reactor and a low-temperature shift (LTS) reactor, a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2). The method further comprises the step of passing, through a CO2 remover, the gas stream to separate CO2 and provide CO2 free gas stream, followed by another step of passing, through a hydrogen separator selected from any or a combination of a pressure swing adsorber (PSA), and a vacuum pressure swing adsorber (VPSA), the CO2-free gas stream to separate hydrogen from the CO2-free gas stream and provide high purity H2 gas.
[0040] In an embodiment, the method comprises the steps of activating a catalyst associated with the HTS reactor using the heat of the process gas stream flowing therethrough, and activating a catalyst associated with the LTS reactor using hydrogen.
[0041] In an embodiment, the effluent gas generated by the PSA and/or the VPSA, upon separation of the H2, is used by the hot air generator to generate hot flue gas. Further, the hot flue gas generated by the hot air generator is used in any or a combination of the first preheater, the second preheater, the first HRSG, and the second HRSG, thereby providing improved thermal efficiency.
[0042] Referring to FIG. 1 and 2, the proposed modular system 200 for generating hydrogen from biomass includes a hydrogen generator 100 as shown in FIG. 1. Further, the proposed modular system 200 includes a control unit 206 operatively coupled to the hydrogen generator 100 through a set of sensors 202 and control valves 204 as shown in FIG. 2, to automate the operation of the hydrogen generator 100 and for efficient and remote monitoring and control of the overall hydrogen generation process through mobile device 210 or any known similar input device of users 212.
[0043] As illustrated in FIG. 1, the hydrogen generator 100 includes a gasifier 102 adapted to receive biomass from one or more sources and convert the received biomass into syngas. The biomass is selected from agricultural residue and municipal solid waste (MSW) and other carbonaceous material.
[0044] In an exemplary embodiment, the gasifier 102 includes a housing adapted to receive the biomass or carbonaceous material from top to form a bed of the biomass material within the gasifier. Further, gasification agents such as steam, hot gas, hot air, oxygen, and the like are allowed to flow through the biomass, to initiate the gasification reaction, which leads to the generation of producer gas or syngas. The producer gas may additionally undergo a high-temperature oxidation zone to crack any tar present in the producer gas, followed by a separation device to provide cleaner syngas (synthesis gas). In another exemplary embodiment, the gasifier 102 is selected from any or a combination of the upward draft gasifier, downward draft gasifier, and cross draft gasifier. Further, based on gas-solid contacting mode, the gasifier 102 may be selected from any or a combination of fixed or moving bed gasifier, fluidized bed gasifier, and entertained flow gasifier, but not limited to the likes.
[0045] The hydrogen generator 100 of the proposed modular system 200 further comprises an acid-alkali scrubber 104 and a de-oxygenator 114 in connection with an output of the gasifier 102, to remove any or a combination of H2S, HCl, HCN, and Ammonia, as well as Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream. In an embodiment, the acid-alkali scrubber 104 comprises an acid scrubber and a water scrubber configured to remove HCl, HCN, and Ammonia from the syngas, and reduce the level of the H2S in the syngas to 10 ppm. Further, a compressor 108 and a first preheater 112-1 are configured to compress and heat the acid-alkali free gas to 7 bar pressure and 225°C temperature. Furthermore, a feed vessel 106 and a gas receiver 110 are configured with the compressor 108 to dampen fluctuations in the acid-alkali free gas before supplying to the first preheater 112-1.
[0046] In an embodiment, an H2S absorber 116 comprising a Zinc Oxide (ZnO) bed is configured to reduce the level of the H2S in the gas to 0.1 ppm. Further, a de-oxygenator 114 (also referred to as De-Oxo 114, herein) comprising a palladium-based catalystis configured to receive the gas and facilitate the reaction between H2 and O2, which results in complete consumption of O2 and generation of water vapor, thereby removing O2 present in the received gas stream and providing the de-oxygenated gas stream. .
[0047] The hydrogen generator 100 of the proposed modular system 200 further comprises a static mixer 120. The static mixer 120 is configured to receive and mix the acid-alkali-free and de-oxygenated gas stream with steam to form a gas-steam mixture. In an embodiment, the acid-alkali-free and de-oxygenated gas stream from the De-Oxo 114 is heated using a second preheater 112-2 that gets heated using a hot air generator 118 connected to an input side of the second preheater 112-2. Further, the static mixer 120 and the first preheater 112-1 are connected to an output side of the second preheater 112-2. The second preheater 112-2 is configured to receive hot air from the hot air generator 118 and correspondingly increase the temperature of the acid-alkali free and de-oxygenated gas stream to 380-400°C. The heated gas stream then enters the static mixer 120 where it gets mixed with steam. In an exemplary embodiment, water enters the system 100 via a phase separator 132, where it passes through a cooler 128 followed by an intercooler 124 and gets preheated. The preheated water then enters a first HRSG 134-1 where it gets converted into steam. This steam then enters the static mixer 120 where it gets mixed with the gas stream to form the gas-steam mixture and lower the temperature of the mixture to 300-330°C.
[0048] A static mixer is a device that is used for the continuous mixing of fluid materials, without moving components. Normally the fluids to be mixed in the static mixer are liquid, however, the static mixer is also used to mix gas streams and steam as used in the present invention. The static mixer disperses gas into liquid or blends immiscible liquids. The energy needed for mixing the gas and steam comes from a loss in pressure as steam flow through the static mixer. In an embodiment, the static mixer is selected containing helical internals. The housed-elements design incorporates a method for delivering two streams of fluids (acid-alkali free and de-oxygenated gas and steam) into the static mixer. As the gas and steam move through the mixer, the non-moving elements continuously blend the materials.
[0049] The hydrogen generator 100 of the proposed modular system 200 comprises a high-temperature shift (HTS) reactor 122 and a low-temperature shift (LTS) reactor 126 fluidically coupled to the static mixer 120. The HTS reactor 122 and the LTS reactor 126 are configured to facilitate a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2). In an embodiment, a catalyst associated with the HTS reactor 122 is activated using the heat of the process gas stream flowing therethrough. Further, a catalyst associated with the LTS reactor 126 is activated using hydrogen.
[0050] In an embodiment, the temperature of the gas stream exiting the HTS reactor 122 is raised to 400°C and passed through the intercooler 124 to cool the gas to 190-200°C. Further, the heat of the passing gas stream is used to preheat the water received from the phase separator 132 for steam generation. Furthermore, the cooled gas stream from the intercooler 124 is passed through the LTS reactor 126 and the cooler 128, which is further passed through a condenser 130 to condense water vapor present in the flowing gas stream. The phase separator 132 then receives the gas stream having condensed water vapor from the condenser 130 and separates the condensed water from the gas stream to provide a moisture-free gas and resupply the separated water to the first HRSG 134-1 for steam generation.
[0051] HTS and LTS 122, 126 are water shift reactors used in the syngas processes to maximize hydrogen production. HTS and LTS reactors shift a portion of the CO content in the gas to CO2 and additional H2 via the water gas shift reaction, which is exothermic. Water shift reactors are classified as HTS or LTS based on the operating temperature of the corresponding reactors. These reactors include a catalyst, which shifts a portion of the CO content in the gas to CO2 and additional H2 via the water gas shift exothermic reaction.
[0052] In HTS, the catalysts comprise primarily of magnetite (Fe3O4) with tri-valent chromium oxide (Cr2O3) added as a stabilizer. The catalyst is usually supplied in the form of ferric oxide (Fe2O3) and hexa-valent chromium oxide (CrO3) and is reduced by the H2 and CO in the shift feed gas as part of the start-up procedure to produce the catalyst in the desired form.
[0053] In LTS, the catalysts operate at temperatures on the order of 205–230°C, making it more controllable and reducing the amount of CO. The LTS catalyst is supplied as copper oxide (CuO) or zinc oxide (ZnO) carrier, and the copper is reduced by heating it in a stream of inert gas with measured quantities of hydrogen.
[0054] Conventionally, in the HTS, heating of the catalyst to achieve the shift temperature is done by using heated Nitrogen at the beginning of the process. However, the present invention is heating the catalyst directly by using the process gas in the HTS, thereby, making the present invention efficient and simplified. The design ensures that no undersidered reactions takes place in the reactor. Further, LTS is activated offline using hydrogen.
[0055] The hydrogen generator 100 of the proposed modular system 200 comprises a CO2 remover fluidically coupled to the HTS 122 and LTS 126 and configured to remove CO2 from the gas stream (generated by the HTS and LTS reactor) to provide CO2 free gas stream. In an embodiment, the CO2 remover is an amine-based CO2 remover system comprising a CO2 absorber 136 and a CO2 stripper 142. The CO2 absorber 136 is configured to absorb the CO2 from the gas stream using a counterflowing amine stream to remove CO2 and provide the CO2-free gas. Further, the CO2-rich amine exiting the CO2 absorber 136 gets heated in a cross-heat exchanger 140 and enters into the CO2 stripper 142 that strips the absorbed CO2 from the amine using steam to form a CO2-steam mixture. Furthermore, the CO2-steam mixture exits the CO2 stripper 142 and gets condensed in an overhead condenser 148 to generate water and separate the CO2. This CO2 can further be utlizied for various industrial applications. The amine geenarted by the CO2 stripper is supplied to the reboiler and the amine is heated and purified further using steam genarted by the second HRSG to obtain lean amine that is supplied back to the CO2 absorber.
[0056] The hydrogen generator 100 of the proposed modular system 200 comprises a hydrogen separator 138 that is selected from any or a combination of a pressure swing adsorber (PSA), and a vacuum pressure swing adsorber (VPSA) (also designated as 138, hereinafter). The hydrogen separator 138 is fluidically coupled to the CO2 remover 136 and configured to separate hydrogen from the CO2-free gas stream to generate the H2 gas having high purity, between 95-99%.
[0057] PSA/VPSA 138 operates on swing adsorption phenomenon, in which, under high pressure, gases tend to be trapped onto solid surfaces or adsorbent material. The higher the pressure, the more gas is adsorbed. When the pressure is dropped, the gas is released or desorbed. PSA uses the swing adsorption phenomenon to separate gases (Hydrogen, herein) in a mixture (CO2-free gas stream, herein) to provide H2 gas, because different gases are adsorbed onto a given solid surface more or less strongly. Further, VPSA is a type of PSA that segregates certain gases (Hydrogen, herein) from a gaseous mixture (CO2-free gas stream, herein) at near ambient pressure to provide H2 gas. The process then swings to a vacuum to regenerate the adsorbent material. VPSA differs from other PSA techniques because it operates at near-ambient temperatures and pressures, and regeneration of adsorbent material.
[0058] In an embodiment, the effluent gas generated by the PSA and/or the VPSA 138, upon separation of the H2, is used by the hot air generator to generate hot flue gas. Further, the hot flue gas generated by the hot air generator 118 is used effectively in the first preheater 112-1, the second preheater 112-2, the first HRSG 134-1, and the second HRSG 134-2 associated with the system 200, thereby providing improved thermal efficiency.
[0059] As illustrated in FIG. 2, the modular system 200 comprises a set of sensors 202 configured at predefined locations in the hydrogen generator 100 to measure and monitor the temperature and attributes of any or a combination of the biomass, the syngas, gas stream, the water, and the steam flowing through one or more components of the hydrogen generator 100. Further, the modular system 200 comprises a set of control valves 204 configured between one or more components of the hydrogen generator 100 to control the flow of any or a combination of the biomass, the syngas, gas stream, the water, and the steam within the hydrogen generator 100. The control unit 206 of the proposed modular system 200 is in communication with the set of sensors 202, and the set of control valves 204. The control unit 206 is configured to monitor and control the temperature, the attributes, and the flow of any or a combination of the biomass, the syngas, the gas stream, the water, and the steam within the modular system 200.
[0060] In an embodiment, the control unit 206 comprises one or more processors operatively coupled to a memory executable by the processors. The control unit 206, upon execution of a first set of instructions by the processors, enables the sensors 202 to monitor the temperature and attributes of the biomass, the syngas, gas stream, the water, and the stream flowing through one or more components of the system. In an exemplary embodiment, the attributes are selected from temperature, pressure, viscosity, flow rate, concentration, but are not limited to the likes. In another exemplary embodiment, the sensors 202 are selected from the temperature sensor, pressure sensor, flow sensor, viscosity sensor, and the like.
[0061] In an exemplary embodiment, the control unit 206 is a programmable logic controller (PLC), but not limited to the like.
[0062] The control unit 206, upon execution of a second set of instructions by the processors, enables the control unit 206 to generate and transmit a set of control signals to one or more components of the hydrogen generator 100 and valves 204 of the modular system 200 to enable the hydrogen generation operation. The control unit 206 may generate the set of control signals based on the attributes monitored by the sensors 202. Further, the control unit 206 may also generate the set of control signals based on a set of instructions provided by a user 212. The user 212 may decide and provide the instructions based on the attributes monitored by the sensors 202.
[0063] The modular system 200 includes a display unit/device 208 in communication with the control unit 206 and hydrogen generator 100, which processes the monitored attributes of the hydrogen generator 100 and correspondingly displays the monitored attributes over the display unit 208 for a user. Futher, the modular system 200 includes mobile device(s) 210 in communication with the control unit 206, which allows the user 212 to remotely monitor and control the operation of the hydrogen generator 100. Accordingly, the user 212 may provide the instructions to the control unit 206, using an input device such as a keyboard, touch panel, buttons, and the like or the mobile device 210, either remotely or on-site.
[0064] Referring to FIG. 3, in another aspect, the present invention elaborates upon a method 300 for generating hydrogen from biomass. Method 300 involves the gasifier, acid-alkali scrubber, de-oxygenator, static mixer, high-temperature shift (HTS) reactor, and low-temperature shift (LTS) reactors, CO2 remover, PSA, VPSA, the preheaters, cooler, intercooler, compressor, phase separator, condenser, and two HRSG associated with the system described in the above paragraphs, but not limited to the likes.
[0065] Method 300 comprises step 302 of gasifying, by a gasifier, the biomass into syngas. Method 300 further comprises step 304 of treating, by an acid-alkali scrubber and a de-oxygenator, the syngas generated in step 302, to remove any or a combination of H2S, HCl, HCN, and Ammonia, and Oxygen present in the syngas to provide an acid-alkali free and de-oxygenated gas stream. Method 300 further comprises step 306 of mixing, in a static mixer, the acid-alkali free and de-oxygenated gas stream generated at step 304 with steam to form a gas-steam mixture.
[0066] Method 300 further comprises step 308 of enabling, by HTS reactor and LTS reactor, a reaction between carbon monoxide (CO) and the steam present in the gas-steam mixture to produce a gas stream comprising carbon dioxide (CO2) and Hydrogen (H2). Further, method 300 comprises step 310 of passing, through a CO2 remover, the gas stream of step 308 to remove CO2 and provide CO2-free gas stream. Furthermore, method 300 comprises step 312 of passing, through a hydrogen separator selected from any or a combination of PSA, and VPSA, the CO2-free gas stream of step 310 to separate hydrogen from the CO2-free gas stream and provide the high purity H2 gas.
[0067] In an embodiment, method 300 comprises the steps of activating a catalyst associated with the HTS reactor using the heat of the process gas stream flowing there through, and activating a catalyst associated with the LTS reactor using hydrogen.
[0068] In an embodiment, the effluent gas generated by the PSA and/or the VPSA at step 312, upon separation of the H2, is used by the hot air generator to generate hot flue gas. Further, the hot flue gas generated by the hot air generator is used in any or a combination of the first preheater, the second preheater, the first HRSG, and the second HRSG, thereby providing improved thermal efficiency.
[0069] In a preferred embodiment, the hydrogen generated with the proposed method of the present invention is utilized in fuel cell vehicles, hydrogen-powered vehicles, and other modes of transportation requiring hydrogen, but not limited to the like.
[0070] Accordingly, the present invention not only addresses the problem associated with the disposal of biomass but also generates clean and industrial-grade, high purityhydrogen using the biomass, in an efficient, cost-effective, and environmentally friendly way. The H2 gas generated with the proposed system and method of the present invention is of high purity, between 95-99%, and hence can be used for various applications.
[0071] The proposed modular system and method of the present invention greatly improve the thermal efficiency of the hydrogen generation process. Those skilled in the art would appreciate that since the hot flue gas generated by the hot air generator is efficiently used for heating other components of the hydrogen generator, as a result, the modular system and method of the present invention reduces the dependence on an additional heat source or fossil fuels for meeting the heating requirements of the proposed system, by way of reutilizing the heat and flue gases generated during the process in a carbon-neutral way.
[0072] It is to be further appreciated by a person skilled in the art that as the present invention is heating the HTS catalyst directly by using the heat of the process gas itself to achieve the shift temperature, unlike the existing techniques wherein, heating of the catalyst to achieve the shift temperature is done by using heated Nitrogen. As a result, the use of the same process gas generated during the hydrogen generation process makes the proposed system and method efficient and also helps reduce the carbon footprint
[0073] Besides, the control unit, and sensors of the proposed modular system and method, automate the hydrogen generator, which enables efficient and remote monitoring and control of the overall hydrogen generation process.
[0074] It is to be further appreciated by a person skilled in the art that the present system for generating hydrogen from biomass is of a highly modular nature. In the embodiments of the present invention, the word modular represents a flexible system, wherein some blocks of the system may be reorganized or replaced or their use may be optional. For example, but not limited to:
• If the desried level of conversion is achived in the HTS (122), then the LTS block (126) may be omitted in the system. In order to avail further more CO conversion, LTS unit can be added on.
• ZnO scrubber is to be installed only if LTS unit is envisaged ( which has stringent requirement for H2S contamination level). If this is not the case , then ZnO scrubber can be deleted.
• CO2 abosorber is to considered, if you would like to obtain CO2 as pure product. If this is not the case, then CO2 absorber as well as HRSG2 get deleted from the scheme.
Also, it is to be noted that the modularity of the proposed system does not vary the scope of the present invention in any manner.
[0075] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art

ADVANTAGES OF THE PRESENT INVENTION
[0076] The present invention provides a modular system and method, which generates clean hydrogen from biomass.
[0077] The present invention addresses the disposal of biomass and the generation of clean and industrial-grade hydrogen fuel.
[0078] The present invention reduces the carbon footprint while generating high purity hydrogen gas.
[0079] The present invention provides a modular system and method of generation of high purity hydrogen which can be used for various industrial and transportation/automotive applications, such as in fuel cells of fuel-cell based vehicles, in hydrogen-powered vehicles, and other modes of transport requiring hydrogen.
[0080] The present invention provides a modular system and method that utilize biomass for the generation of hydrogen fuel, in an efficient, cost-effective and environmentally friendly way.
[0081] The present invention provides a modular system and method for generating clean hydrogen from biomass, which reutilizes the heat and flue gas generated during the process in a carbon-neutral way.
[0082] The present invention provides a control system for the hydrogen generation system and method, which automatically, remotely, and efficiently monitors and controls the overall hydrogen generation process.