WO2017163266A1 - Système et procédé de production de gaz de synthèse riche en hydrogène pour la génération d'hydrogène - Google Patents

Système et procédé de production de gaz de synthèse riche en hydrogène pour la génération d'hydrogène Download PDF

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WO2017163266A1
WO2017163266A1 PCT/IN2017/050105 IN2017050105W WO2017163266A1 WO 2017163266 A1 WO2017163266 A1 WO 2017163266A1 IN 2017050105 W IN2017050105 W IN 2017050105W WO 2017163266 A1 WO2017163266 A1 WO 2017163266A1
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biomass
oxy
steam
hydrogen
gasification
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PCT/IN2017/050105
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English (en)
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S Dasappa
Sandeep Kumar
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Indian Institute Of Science
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/02—Fixed-bed gasification of lump fuel
    • C10J3/20—Apparatus; Plants
    • C10J3/22—Arrangements or dispositions of valves or flues
    • C10J3/24—Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed
    • C10J3/26—Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed downwardly
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/02—Fixed-bed gasification of lump fuel
    • C10J3/06—Continuous processes
    • C10J3/16—Continuous processes simultaneously reacting oxygen and water with the carbonaceous material
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
    • C10J2300/0913—Carbonaceous raw material
    • C10J2300/0916—Biomass
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
    • C10J2300/0953—Gasifying agents
    • C10J2300/0959—Oxygen
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
    • C10J2300/0953—Gasifying agents
    • C10J2300/0973—Water
    • C10J2300/0976—Water as steam
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/12—Heating the gasifier
    • C10J2300/1223—Heating the gasifier by burners
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1603—Integration of gasification processes with another plant or parts within the plant with gas treatment
    • C10J2300/1618—Modification of synthesis gas composition, e.g. to meet some criteria
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock
    • Y02P20/145—Feedstock the feedstock being materials of biological origin

Definitions

  • the present subject matter relates, in general, to a process for production of syngas and, in particular, to production of hydrogen-rich syngas by biomass gasification.
  • Hydrogen is typically used in ammonia production, petroleum refining, and methanol synthesis. As hydrogen is a clean and green energy source, it can be a promising fuel source for future energy needs. Unlike conventional and renewable energy sources, such as fossil fuels, hydro, wind, and solar energy, hydrogen cannot be mined or harvested. Hydrogen can only be synthesized or produced " . " Hydro ' gen”is typically produced by techniques such as steam methane reforming, partial oxidation of methane, electrolysis, and the like. Most (>95%) of the hydrogen produced is from fossil fuel source. Production of hydrogen from fossil fuel source causes production of produce carbon dioxide as byproduct. Other production techniques which do not depend on fossil fuels, for example, electrolysis, have low thermal efficiency.
  • Fig. 1 illustrates the. process for production of hydrogen-rich syngas, in accordance with an implementation of the present subject matter.
  • Fig. 3 depicts variation of FPR with oxygen content in a gasification medium comprising oxygen and nitrogen, in accordance with an implementation of the present subject matter.
  • Fig. 4 depicts variation of FPR with variation in moisture content in wet biomass, in accordance with an implementation of the present subject matter.
  • Fig. 5 depicts variation of FPR with mass flux of biomass, in accordance with an implementation of the present subject matter.
  • Fig. 6 depicts temperature profile within the downdraft gasifier with varying heights beyond the ignition nozzle, in accordance with an implementation of the present subject matter.
  • Fig. 7(a) and Fig. 7(b) depict a graphical representation of syngas composition as obtained by the method, in accordance with an implementation of the present subject matter.
  • Fig. 8 depicts H 2 O fraction in syngas and H 2 yield at varying Steam-to- Biomass Ratios (SBRs), in accordance with an implementation of the present subject matter.
  • SBRs Steam-to- Biomass Ratios
  • Fig. 9 depicts variation of average bed temperature and H 2 yield with SBR, in accordance with an implementation of the present subject matter.
  • Fig. 10 depicts variation of rate kinetic parameters ki and ks with the average bed temperature and respective H 2 yield, in accordance with an implementation of the present subject matter.
  • Fig. 11 depicts carbon conversion at different SBRs, in accordance with an implementation of the present subject matter.
  • Fig. 12 depicts variation of H 2 /CO ratio with SBR, in accordance with an implementation of the present subject matter.
  • Fig. 13 depicts variation in energy yield of syngas per unit mass of fuel and LHV of syngas with SBR, in accordance with an implementation of the present subject matter.
  • Fig. 14 is a schematic representation of exergy analysis for oxy-steam gasification, in accordance with an implementation of the present subject matter.
  • Fig. 15 depicts variation in fraction of exergy input in 0 2 and steam generation at various SBRs, in accordance with an implementation of the present subject matter.
  • Fig. 16 depicts variation in energy and exergy efficiency with SBR, in accordance with an implementation of the present subject matter.
  • Fig. 17 depicts variation in product gas exergy components with SBR, in accordance with an implementation of the present subject matter.
  • the present subject matter relates to a process for production of hydrogen-rich syngas by biomass gasification eventually leading to produce pure hydrogen.
  • Hydrogen is likely to be used in transport sector and the distributed power generation sector as it is a clean energy source. Hydrogen can be produced but cannot be mined or harvested like fossil fuels, solar energy, wind energy, and the like.
  • Some techniques for production of hydrogen are steam methane reforming, electrolysis, auto thermal reforming of methane, etc. These techniques, typically, produce carbon dioxide as by-product during production of hydrogen. Moreover, these are typically large scale processes which require high capital investment.
  • biomass gasification is another technique that can be used for production of hydrogen.
  • Biomass gasification is a sub-stoichiometric combustion process. It includes stages of pyrolysis, oxidation, and reduction. These stages are typically carried out in a gasifier. Biomass gasification reaction is as shown below:
  • Gasification techniques such as coal gasification, direct biomass gasification, biomass pyrolysis have been used for production of gaseous products.
  • the gaseous product typically, comprises hydrogen, carbon monoxide, carbon- dioxide, methane and nitrogen.
  • these techniques are typically not used for commercial scale hydrogen production as hydrogen content in biomass is about 6% by weight.
  • production of pure hydrogen from biomass is limited by char formation in the air gasification process and amount of hydrogen present in the gaseous product.
  • presence of nitrogen due to air gasification of biomass further leads to dilution of hydrogen in the gaseous product.
  • the present subject matter provides a process for producing hydrogen-rich syngas by biomass gasification.
  • the process comprises the step of determining a height above the ignition nozzle in a downdraft gasifier for introduction of one of oxygen and an oxy-steam mixture in the downdraft gasifier, an important design parameter to ascertain required residence time reactants.
  • the height is based on mass-flux of biomass, diameter of biomass particles, relevant ambient temperature for water gas shift reaction to proceed in the forward direction, residence time, and thermal diffusivity.
  • the process further comprises the step of charging biomass through a lock-hopper into the downdraft gasifier and introducing the one of oxygen and oxy-steam mixture in the downdraft gasifier at the height determined.
  • Mass-flux of the reactant (oxy-steam) is varied to control the biomass mass flux in a range of 0.05- 0.11 kg/m s in order to moderate the flame propagation rate (FPR) in the downdraft gasifier.
  • the process of the present subject matter uses oxy-steam as the gasification medium for biomass gasification.
  • the steam provides endothermicity and enhances hydrogen yield.
  • the use of oxy-steam as gasification medium increases production of hydrogen by causing water gas reaction (WGR) and water gas shift reaction (WGSR) to occur in the gasifier. This mitigates the need for an additional catalytic cracking system to implement WGR and WGSR.
  • the height at which the oxygen or oxy-steam mixture is introduced is based on mass-flux of biomass, diameter of biomass particles, relevant ambient temperature for water gas shift reaction to proceed in the forward direction, residence time, and thermal diffusivity. These factors affect the FPR in the gasifier, which further affects the gas resident time, biomass conversion level and gas quality.
  • the process further comprises introducing superheated steam through at least one of a plurality of elevations in addition to the oxy-steam mixture.
  • the introduction of superheated steam can help in controlling the FPR throughout the gasifier.
  • the process of the present subject matter also helps in generating clean gas with almost negligible HHCs, especially tars.
  • the present subject matter also describes the downdraft gasifier in which the process can be implemented.
  • Fig. 1 illustrates the process 100 for production of hydrogen -rich syngas, in accordance with an implementation of the present subject matter.
  • the process 100 at step 102, comprises determining a height above a fixed bed in a downdraft gasifier for introduction of one of oxygen and an oxy-steam mixture in the downdraft gasifier.
  • the height is based on mass-flux of biomass, diameter of biomass particles, temperature for water gas shift reaction to proceed in the forward direction, residence time, and thermal diffusivity.
  • the height is determined by equation 1 as given below.
  • the equation 1 was derived by empirical analysis of gasification.
  • K c is a constant having value 0.012 m 4 k 1'8 s L6 kg "1 ;
  • m w is mass flux of biomass in kg/(m .h);
  • d w is diameter of biomass in millimeters
  • T' is temperature of one of oxygen or oxy-steam mixture injected in reactor in K;
  • d is diameter of the downdraft gasifier in meters
  • a is the thermal diffusivity in mm /s.
  • the diameter of the wood pieces is also related to the diameter of the reactor.
  • d/d w varies between 10-15 for d up to 0.25 m; 15-20 for d between 0.25 to 0.5 m; 20-25 for d 0.5 to 1 m; and beyond 1 m the d w of maximum of 125 mm.
  • the process comprises pre-mixing oxygen and superheated steam prior to introducing the oxy-steam mixture in the downdraft gasifier at the determined height.
  • a ratio of oxygen to super- heated steam in the oxy-steam mixture is in a range of 1:50 to 1: 150 (on mass basis).
  • the ratio of oxygen to super-heated steam varies based on mass-flux and moisture content in the biomass. For example, the ratio of oxygen to super-heated steam increases with increase in mass flux. Similarly, ratio of oxygen to super-heated steam increases with increase in moisture content in the biomass. In an implementation, the moisture content in the biomass is in a range of 0-50% on mass basis.
  • the step 104 comprises charging biomass through a lock-hopper into the downdraft gasifier.
  • the biomass is pre-treated by techniques, such as torrefaction and pelletized.
  • the process 100 comprises introducing one of oxygen and oxy-steam mixture at the height determined in step 102.
  • the process 100 at step 108 comprises igniting the biomass.
  • the biomass is ignited by a heater or a burner at an ignition nozzle at a bottom end of the downdraft gasifier.
  • the one of oxygen and oxy-steam mixture is continuously introduced after igniting the biomass.
  • introduction of one of oxygen and oxy-steam mixture is halted until a pre-determined interval of time till the complete ignition of the biomass in the downdraft gasifier.
  • the process 100 comprises introducing superheated steam at at least one of a plurality of elevations in addition to the oxy-steam mixture. Introducing superheated steam provides endothermicity due to high latent heat of vaporization of water. Endothermicity reduces rate of pyrolysis and thereby the FPR. In addition to providing endothermicity, superheated steam increases hydrogen in the syngas produced by reacting with char formed, i.e., by water gas reaction (WGR) and water gas shift reaction (WGSR) as given below:
  • WGR water gas reaction
  • WGSR water gas shift reaction
  • the process 100 comprises collecting the hydrogen-rich syngas.
  • the collected hydrogen-rich syngas is scrubbed to remove particulates and any water washable components. It is to be understood that other techniques can be used for purifying the hydrogen-rich syngas as will be obvious to a person skilled in the art.
  • the hydrogen-rich syngas is routed for use in combustion processes. As mentioned previously, the process 100 is carried out in a downdraft gasifier as illustrated in Fig. 2.
  • FIG. 2 illustrates schematic of the downdraft gasifier 200, in accordance with an implementation of the present subject matter.
  • the downdraft gasifier 200 comprises a gasification chamber 202.
  • the gasification chamber 202 comprises an inlet 204 at a top end of the gasification chamber 202 for charging of the biomass.
  • the inlet 204 is coupled to a lock hopper 206.
  • the lock hopper 206 helps in operating the downdraft gasifier 200 at a pressure upto 30 bar.
  • the lock hopper 206 also ensures a leak proof operation during charging of biomass into the downdraft gasifier 200.
  • the downdraft gasifier 200 comprises a plurality of inlets 208a, 208b at the plurality of elevations along a wall 210 of the gasification chamber for introduction of the oxy-steam mixture and the superheated steam into the gasification chamber 202.
  • the plurality of inlets 208a, 208b are coupled to an oxygen supply and a steam boiler.
  • the plurality of inlets 208a, 208b can be coupled to a mixer, an atomizer, or a combination thereof. These can be further coupled to the oxygen supply and steam boiler to receive and pre-mix the oxygen and steam to provide the oxy-steam mixture.
  • the oxy-steam mixture is then introduced via the plurality of inlets 208a, 208b in the wall 210.
  • the wall 210 is internally lined with ceramic to insulate the gasification chamber 202.
  • the gasification chamber 202 also comprises an ignition nozzle 212 at a bottom end of the gasification chamber 202 for igniting the biomass.
  • the gasification chamber 202 also comprises an outlet 214 at the bottom end for collecting the hydrogen-rich syngas generated in the downdraft gasifier 200.
  • the outlet 214 is substantially below the ignition nozzle 212.
  • the outlet 214 is coupled to a scrubber 216.
  • the scrubber 216 helps in separating particulates and moisture and helps in cooling the hydrogen-rich syngas.
  • the scrubber 216 is further coupled downstream to a gas analyser 218 and flow measuring device 220.
  • the gas analyser 218 analyses and provides composition of the hydrogen-rich syngas.
  • the flow measuring device 220 measures flow of the hydrogen-rich syngas.
  • the downdraft gasifier 200 has a turn- down ratio in a range of 1 :3 to 1 :4.
  • the gasification chamber 202 also comprises a plurality of thermocouples 222 along its wall at different elevation to measure temperatures at different elevation. The temperatures measured can be used to generate a thermal profile in the gasification chamber 202, as will be explained later.
  • the gasification chamber 202 is coupled to an oxygen supply 226 and steam boiler 224.
  • the oxygen supply 226 is coupled to the plurality of inlets 208a.
  • the oxygen supply 226 supplies oxygen to the gasification chamber 202.
  • the steam boiler 224 provides superheated steam to the gasification chamber 202.
  • the steam boiler 224 is coupled to the plurality of inlets 208b.
  • the oxygen from the oxygen supply 226 and steam from the steam boiler 224 at pre-mixed at a plurality of junctions 230.
  • the opening and closing of the plurality of junctions 230 can be controlled by valves as will be understood by a person skilled in the art.
  • valves can be a unidirectional valve for preventing backflow of oxygen and steam into the oxygen supply 226 and steam boiler 224.
  • the valves can be controlled to cause mixing or prevent mixing of oxygen with steam as will needed for the process 100.
  • the plurality of junctions 230 can be provided at any point in the oxygen and steam supply lines as will be understood by a person skilled in the art.
  • the gasification chamber 202 is coupled to a burner 228.
  • the burner 228 is used for providing burning syngas generated for studying thermal properties of syngas.
  • the burner 228 can also be used for providing heat for thermal applications by using the syngas as fuel. It is to be understood that the burner 228 can also be replaced by an engine for power generation, and the like, as will be understood by a person skilled in the art.
  • SBR steam to biomass ratio
  • Equivalence ratio as used in the examples is defined as the actual oxygen to fuel ratio divided by the stoichiometric oxygen to fuel ratio.
  • LHV Lower Heating Value
  • EXAMPLE 1 VARIATION OF FPR WITH VARIATION IN GASIFICATION MEDIUM
  • Fig. 3 depicts variation of FPR with oxygen content in a gasification medium comprising oxygen and nitrogen, in accordance with an implementation of the present subject matter.
  • the FPR increases.
  • Reduction in residence time reduces heat penetration inside the particle, pyrolysis rate, and amount of gases generated (including hydrogen) with incomplete conversion of biomass further leading to unstable operation.
  • the gasification medium comprising oxygen should include a diluent.
  • the diluent is to induce endothermicity during gasification. Endothermicity can be induced by using wet biomass with oxygen as gasification medium or by using the oxy-steam mixture as gasification medium with dry biomass.
  • FIG. 4 depicts variation of FPR with variation in moisture content in wet biomass, in accordance with an implementation of the present subject matter.
  • Gasification medium used was oxygen.
  • the FPR decreases with increase in moisture content as drying induce necessary endothermicity.
  • Fig. 5 depicts variation of FPR where gasification medium used is the oxy-steam mixture and biomass used is dry biomass, in accordance with an implementation of the present subject matter.
  • the oxy-steam mixture in this example, comprised 21% oxygen and 79% steam.
  • Fig. 5 also depicts comparison of FPR with different gasification medium at different bed temperatures.
  • the FPR for the oxy-steam mixture indicated by curve 502 is similar to that of air preheated to 600K indicated by curve 504.
  • the curve 502 also indicates that an operating window for gasification based on mass flux of biomass for oxy-steam mixture exists. As the mass flux increases, FPR increases and reaches a maximum of 0.15 mm/s and then reduces. This indicates that mass flux can be varied in a range of 0.05-0.11 kg/m to maintain the FPR in a range of 0.05 mm/s-0.15 mm/s.
  • Fig. 6 depicts temperature profile within the downdraft gasifier 200 with varying heights beyond the ignition nozzle. Temperature at the varying heights was measured using a plurality of temperature sensors, such as thermocouples, at the varying heights. The temperature data was acquired using the IO tech PDQ2. Fig. 6 indicates temperature within the downdraft gasifier varying with height above the ignition nozzle and gasifier operation time. From Fig. 6 it can be concluded that introducing gasification medium at varying heights can modify or vary the FPR which could affect residence time and temperature profile in the downdraft gasifier 200. Equation 1, as disclosed previously, was derived by empirical analysis of gasification. Therefore, height at which the gasification medium is to be introduced in the downdraft gasifier 200 can be calculated in equation 1 to establish the required thermal profile as indicated in Fig. 6.
  • EXAMPLE 2 OPERATING CONDITIONS WITH VARIABLE SBR AND ER
  • Table 1 also shows the variation of H 2 to CO ratio and LHV with SBR.
  • H 2 to CO ratio is observed to be increasing with increase in SBR.
  • LHV is observed to be decreasing with increase in SBR. This is due to the higher rate of reduction in CO mole fraction compared to increment in H 2 yield.
  • the lower heating value (LHV) of syngas was found to be varying from7.4 to 8.8 MJ Nm .
  • 66 g of H 2 per kg of biomass was obtained at SBR of 0.75 and ER of 0.21.
  • Stable operation of oxy-steam gasification of wood chips was also achieved with hydrogen yield as high as 104 g per kg of biomass at SBR of 2.7 and ER of 0.3.
  • EXAMPLE 3 COMPARATIVE DATA OF WET BIOMASS GASIFICATION WITH OXYGEN AS GASIFICATION MEDIUM, AND DRY BIOMASS GASIFICATION WITH OXY-STEAM AS GASIFICATION MEDIUM
  • Fig. 8 depicts an increase in volume fraction of H 2 O in syngas and H 2 yield with SBR. This suggests significant enhancement in char-steam reaction with increase in SBR. Also, with increase in SBR, bed temperature is also found to be decreasing. 0 2 fraction in the reactant reflecting the ER can be increased to maintain the desired bed temperature.
  • Fig. 9 depicts variation of average bed temperature at different SBRs, with respect to the H 2 yield and ER. From Fig. 9 it can be observed that high bed temperature can be maintained by increasing the ER. This results in enhanced char conversion and H 2 yield at higher SBRs.
  • Fig. 10 depicts rate constants using data labels of SBR to indicate the respective proportional value of pH 2 O. Ki and K5 vary exponentially with temperature, as shown in Fig. 10. The set of data points on the top right hand side in Fig. 10 indicate cumulative impact of temperature and pH 2 O on the H 2 yield.
  • Fig. 11 indicates carbon conversion inside the downdraft gasifier 200, in accordance with an implementation of the present subject matter. From Fig.
  • Fig. 12 depicts variation of H 2 /CO ratio with SBR. From Fig. 12 it can be observed that there was substantial increase in H 2 /CO ratio beyond SBR of 1.5.
  • Table 3 presents gas composition data at different SBR. It can be observed from Table 3 that C0 2 volume fraction remains roughly constant between 25-26% till SBR of 1.5 and later increases substantially with SBR. The H 2 /CO ratio reduces after SBR of 1.5, from 1.63 to 1.5.
  • WGSR is mildly exothermic. Calorific value of H 2 is less than CO (14.5% lower on molar basis). This implies that once the carbon boundary is reached, no extra fuel gas is generated. However, chemical energy is transferred from CO to H 2 . This further contributes to a higher yield of H 2 but at the cost of efficiency.
  • Oxy-steam gasification showed an increase in physical exergy fraction from 5.9 to 11.3% with the increase in SBR from 0.75 to 2.7.
  • chemical mixture exergy fraction during air gasification was found to be 3.2% compared to oxy-steam gasification, which showed an increment 1.7% to 2.8% in same range of SBR.
  • Fig. 14 provides a schematic representation of exergy flow, in accordance with an implementation of the present subject matter. Total energy input is split in to various parts where 62-81% of energy input is in fuel form, i.e., biomass. 6- 19% energy input is corresponding to heat for providing steam which, further, is a function of SBR.
  • Fig. 15 presents the exergy input fraction in 0 2 and steam generation with a change in SBR. Exergy input for 0 2 separation and steam generation were roughly same for low SBR, but with the increase in SBR, the steam exergy increased significantly from 6% to over 18%. The marginal increase in oxygen level to maintain bed temperature has no significant impact on the exergy input.
  • Fig. 16 represents exergy and energy efficiency for air gasification and oxy-steam gasification with varying SBR, in accordance with an implementation of the present subject matter.
  • Physical exergy in syngas was found to be increasing from about 6% to 12% with increase in SBR from 0.75 to 2.7. However, physical exergy was found to below with a value of 3.2% in case of air gasification. Presence of unreacted steam in syngas can be considered to contribute to the physical exergy loss, which showed an increase from 13% to76% in the product gas. Reduction in energy efficiency at higher SBR was found. This could be due to the loss in sensible heat or physical exergy in the syngas.
  • the present invention provides a method for hydrogen-rich syngas generation where the syngas does not comprise nitrogen.
  • Mass flux of reactant (oxy-steam) can be varied for stable operation. Flame propagation rate can be controlled to increase residence time and to increase hydrogen yield.
  • the reactor and process steps of the present invention are used to generate clean hydrogen rich syngas of medium calorific value and low tar content.
  • the reactor of the present invention possesses the capability to generate hydrogen rich syngas at pressures marginally higher than ambient.
  • H 2 /CO ratio in the generation of syngas varies from 1 : 1 to 3.9: 1. ER for a given SBR is maintained for a stable and sustained operation.
  • H 2 yield close to thermodynamic limit of 100 g of hydrogen per kg of biomass was achieved. Carbon boundary at SBR of 1.5 was achieved.
  • wet biomass along with 0 2 as reactant with moisture to biomass (H 2 O/Biomass) ratio between 0.6 to 1.1 is used on mass basis with H 2 yield reaching upto 66 g/kg of dry biomass and 33% volume fraction.

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  • Processing Of Solid Wastes (AREA)

Abstract

L'invention concerne un procédé (100) pour produire un gaz de synthèse riche en hydrogène par gazéification de biomasse. Il comprend la détermination d'une hauteur au-dessus d'un lit fixe dans un gazéifieur à tirage vers le bas (200) pour l'introduction de l'un parmi l'oxygène et un mélange d'oxy-vapeur dans le gazéifieur à tirage vers le bas (200). La hauteur est basée sur le flux massique de la biomasse, le diamètre des particules de biomasse, la température ambiante pertinente pour la poursuite de la réaction de conversion du CO vers l'avant et la diffusivité thermique. Le procédé (100) consiste à charger la biomasse à travers une trémie de verrouillage (206) dans le gazéifieur à tirage vers le bas (200) et à introduire le mélange d'oxy-vapeur dans le gazéifieur à tirage vers le bas (200) à la hauteur déterminée. Le charbon dans la zone d'allumage au fond du réacteur est ensuite allumé. Un gaz de synthèse riche en hydrogène est ensuite collecté à partir du gazéifieur à tirage vers le bas (200). Le flux massique de la biomasse est amené à varier dans une plage de 0,05-0,11 kg/m2s pour réguler un taux de propagation de flamme (TPF) dans le gazéifieur à tirage vers le bas (200).
PCT/IN2017/050105 2016-03-21 2017-03-21 Système et procédé de production de gaz de synthèse riche en hydrogène pour la génération d'hydrogène WO2017163266A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114854453A (zh) * 2022-03-22 2022-08-05 北京科技大学 用于高炉喷吹的生物质富氢微粉及合成气的制备方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2963354A (en) * 1956-06-27 1960-12-06 Texaco Inc Process for the gasification of solid carbonaceous fuels
EP1687390A2 (fr) * 2003-11-04 2006-08-09 ITI LImited Gazeification

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2963354A (en) * 1956-06-27 1960-12-06 Texaco Inc Process for the gasification of solid carbonaceous fuels
EP1687390A2 (fr) * 2003-11-04 2006-08-09 ITI LImited Gazeification

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114854453A (zh) * 2022-03-22 2022-08-05 北京科技大学 用于高炉喷吹的生物质富氢微粉及合成气的制备方法
CN114854453B (zh) * 2022-03-22 2023-03-28 北京科技大学 用于高炉喷吹的生物质富氢微粉及合成气的制备方法

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