WO2023148784A1 - An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier - Google Patents

An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier Download PDF

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Publication number
WO2023148784A1
WO2023148784A1 PCT/IN2023/050124 IN2023050124W WO2023148784A1 WO 2023148784 A1 WO2023148784 A1 WO 2023148784A1 IN 2023050124 W IN2023050124 W IN 2023050124W WO 2023148784 A1 WO2023148784 A1 WO 2023148784A1
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Prior art keywords
gasifier
feed
gas
ash
bed
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Ceased
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PCT/IN2023/050124
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French (fr)
Inventor
Prakash Dhondiram CHAVAN
Sujan SAHA
Nilesh D DHAIGUDE
Vishal CHAUHAN
Gajanan SAHU
Sudipta Datta
Pradeep Kumar Singh
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Council of Scientific and Industrial Research CSIR
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Council of Scientific and Industrial Research CSIR
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Priority to JP2024547006A priority Critical patent/JP2025505660A/en
Priority to CN202380020790.7A priority patent/CN118660949A/en
Priority to US18/836,252 priority patent/US20250197747A1/en
Priority to AU2023214885A priority patent/AU2023214885A1/en
Publication of WO2023148784A1 publication Critical patent/WO2023148784A1/en
Anticipated expiration legal-status Critical
Priority to ZA2024/06117A priority patent/ZA202406117B/en
Ceased legal-status Critical Current

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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
    • C10J3/72—Other features
    • C10J3/723—Controlling or regulating the gasification process
    • 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
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/482—Gasifiers with stationary fluidised bed
    • 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
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/485—Entrained flow gasifiers
    • C10J3/487—Swirling or cyclonic gasifiers
    • 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
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/50—Fuel charging devices
    • C10J3/503—Fuel charging devices for gasifiers with stationary fluidised bed
    • 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
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/52—Ash-removing devices
    • C10J3/523—Ash-removing devices for gasifiers with stationary fluidised bed
    • 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
    • C10J3/72—Other features
    • C10J3/82—Gas withdrawal means
    • 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
    • C10J3/72—Other features
    • C10J3/82—Gas withdrawal means
    • C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/02—Dust removal
    • C10K1/026—Dust removal by centrifugal forces
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/04—Purifying combustible gases containing carbon monoxide by cooling to condense non-gaseous materials
    • C10K1/06—Purifying combustible gases containing carbon monoxide by cooling to condense non-gaseous materials combined with spraying with water
    • 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
    • C10J2200/00—Details of gasification apparatus
    • C10J2200/15—Details of feeding means
    • C10J2200/152—Nozzles or lances for introducing gas, liquids or suspensions
    • 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
    • C10J2200/00—Details of gasification apparatus
    • C10J2200/15—Details of feeding means
    • C10J2200/156—Sluices, e.g. mechanical sluices for preventing escape of gas through the feed inlet
    • 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
    • C10J2200/00—Details of gasification apparatus
    • C10J2200/15—Details of feeding means
    • C10J2200/158—Screws
    • 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
    • C10J2200/00—Details of gasification apparatus
    • C10J2200/33—Laboratory scale gasifiers
    • 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
    • C10J2300/0913—Carbonaceous raw material
    • C10J2300/093—Coal
    • 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
    • C10J2300/0956—Air or oxygen enriched air
    • 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
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1678—Integration of gasification processes with another plant or parts within the plant with air separation
    • 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
    • C10J2300/1687—Integration of gasification processes with another plant or parts within the plant with steam generation
    • 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
    • C10J2300/169—Integration of gasification processes with another plant or parts within the plant with water treatments
    • 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
    • C10J2300/1693—Integration of gasification processes with another plant or parts within the plant with storage facilities for intermediate, feed and/or product

Definitions

  • the present invention relates to a development of oxygen enriched air blown pressurized fluidized bed pilot scale gasifier to evaluate gasification performance of coal, biomass, washery rejects and their blends in any proportion. More particularly, the present invention relates to an oxygen enriched air blown pressurized fluidized bed gasification pilot scale facility with refractory lined gasifier having feed rate carrying capacity up to 60 kg/hour, maximum operating temperature up to 1050°C and pressure up to 10 kg/cm 2 .
  • the facility consists of gaseous and solid feeding section, gasification section, ash withdrawal section, and gas Cooling & Cleaning section. Besides gasification performance analysis, this invention is also to study agglomeration characteristics, entrainment and other fluidized bed gasification related parameters.
  • India has a vast reserve of coal dominating inferior grade high ash non-coking coal.
  • the high ash content of Indian coal is a crucial barrier in the development of suitable technology.
  • the Entrained flow gasifier is a matured one but not recommended for high ash coal due to its enormous heat loss and thermal imbalance associated with the outgoing molten slag.
  • Fixed bed gasification technology is restricted up to the coal of 30% ash, at the same time it creates a significant amount of hazardous tar requiring a large amount of capital investment for the downstream processing.
  • utilization of high ash coal by the aforementioned technologies imply economic and environmental penalties in terms of feed beneficiation and downstream processing for various applications such as, power, chemicals, fertilizer, DRI as well as thermal.
  • fluidized bed gasifier is capable to gasify wide range of feedstock. It is most suitable to utilize high ash coal without beneficiation for reducing ash level as well as efficient to handle not only biomass but also washery rejects and their blends in any proportion for different applications with negligible tar formation leading to the reasonably reduction of downstream CAPEX & OPEX.
  • the heat transfer between gas and solid phases is better owing to the fluid like behavior of the reactants.
  • high ash coals have number of disadvantages like low heat value, operational constraints, low efficiency etc. Agglomeration of ash particles may lead to defluidization of the bed which results in the shutdown of the plant due to inherent properties of some feedstock.
  • the plant has a pressure vessel containing a hot fluidized sand bed.
  • the biomass is pre-dried to a moisture content of 10% to 35% by weight.
  • a steam-free oxygencontaining gas is fed and distributed, through a grid system at the bottom of the hot sand bed, to hold the bed in a fluidized state and to form, in its lower portion, an oxygen-rich heat-forming combustion zone and, in its upper portion, a hydrogen-rich gas-forming pyrolysis zone.
  • the pre-dried biomass is uninterruptedly fed in the pyrolysis zone at essentially the center of the hot fluidized bed, this center being determined when the sand bed stands at rest.
  • the fluidized bed is held at an operating temperature of 750 to 860oC. under an operating pressure of 400 kPa to 1750 kPa by controlling the feeding rate of the fluidized gas as well as the feeding rate of the biomass.
  • the gases and biomass residue released from the hot fluidized bed are removed in a gas stream from the head space above the bed and sent to a primary cyclone which separates the useful gases from most of the biomass residue the latter being returned to the combustion zone of the bed.
  • the gases and the biomass residue that have remained in the first cyclone are then moved into a second cyclone where the useful gases are collected and the biomass residue discarded.
  • the drawbacks are;
  • Provision for removal of acidic components from the gas is not available. Provision of pre-heating and through missing of gaseous reactants before entering into the gasifier is not available.
  • a fluidized bed gasifier for gasifying a fuel first receives heat indirectly from a combusting fluidized bed disposed at least partially within the gasifier fluidized bed.
  • Fuel for the combusting bed may be provided by removing a portion of the fluidized fuel from the gasifier bed and transporting this removed portion into the combusting bed. Heat is transferred across the conductive walls of the combustor vessel.
  • Product gas heating value is increased by separately removing the products of combustion from the gasifier and by recycling a portion of the product fuel gas as the fluidizing gas for the gasifier fluidized bed.
  • a radiation shield is also provided to reduce heat loss from the gasifier bed and to remove elutriated material from the product fuel gas.
  • first stage gasifier is a circulating fluidized bed transport gasifier operating in the temperature range of approximately 900°C to 1100°C
  • second stage gasifier is a fluidized bed partial oxidizer operating in the temperature range of approximately 1100°C to 1400°C.
  • the first stage gasifier serves as a primary gasifier converting up to 90% of carbon to syngas components along with some tar.
  • the residual char carbon and tar from the gasifier is then thermally cracked and converted to syngas components in a second stage high temperature fluidized bed oxidizer.
  • the two-step process can achieve over approximately 98% overall carbon conversion to syngas components.
  • the system is only for high ash, high ash fusion temperature bituminous coal as well as system seems to be complicated considering the fabrication and operation. Also there is no provision of on line gas analysis of the product gas.
  • Patent Application No. CN201610944225 discloses a technique for carrying out coal gasification by a bubbling fluidized bed.
  • the technique comprises the following steps like, coal grinding and drying; coal pressurization and coal feeding; coal gasification; crude de-dusting by cyclone separation; waste heat recovery; synthetic gas deep de-dusting and purification; and clinker treatment.
  • the system is only for coal gasification.
  • Other feed materials like biomass/ coalbiomass blends cannot be utilized in the system.
  • the invention relates to methods of operating fluidized bed systems combining a dense fluidized bed and an entrained fluidized bed wherein the beds contain particle components having long-term chemical and physical stability in the system, one particle component being retained in the dense fluidized bed while the other is entrained and recirculated through a portion of the dense bed to increase residence time and promote more complete reaction of the reactant feed particles therein.
  • the invention relates to the operation of such a multi-solid system wherein the dense bed is operated with two distinct temperature zones for optimum control of a fuel combustion or gasification and capture of released sulfur by an added sorbent.
  • the method is utilized for both combustion and gasification of high-sulfur coal.
  • this is a circulating fluidized bed type and is used for coal only. Operation of the device is complicated too particularly to maintain two reaction zones inside the reactor.
  • a fluidized-bed gasification apparatus for gasifying combustibles in a fluidized-bed furnace comprises a gasification furnace for gasifying combustibles therein and a combustion furnace for combusting combustible components therein.
  • the fluidized medium moves between the gasification furnace and the combustion furnace, and exhaust gas discharged from another combustor is utilized as a fluidizing gas in the combustion furnace.
  • PFBG Pressurized Fluidized Bed Gasification
  • this invention relates to an air- blown Pressurized Fluidized Bed Gasification (PFBG) pilot scale Test Facility having feed rate carrying capacity varying from 7 kg/hour to 20 kg/hour. It has maximum operating temperature up to 1000°C and pressure up to 3 kg/cm 2 .
  • the test facility consists of externally heated metallic pressurized fluidized bed gasifier.
  • the system does not have refractory lined gasifier.
  • the gasifier is not capable to conduct gasification performance analysis in oxygen-steam mixture as it not equipped with oxygen generator.
  • dual feeding arrangement comprising of rotary feeder and screw feeder.
  • the main objective of the present invention is to develop oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier to evaluate gasification performance of coal, biomass, washery rejects, and their blends in any proportion in the actual atmosphere which prevails in the commercial gasifier including combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications which obviates the drawbacks of the hitherto known prior art as detailed above.
  • Another objective of the present invention is to develop oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier to evaluate gasification performance of coal, biomass, washery rejects, and their blends in any proportion in air/ oxygen/oxygen enriched air/ steam as well as their mixture of any ratio as per process requirement.
  • Yet another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasifier to assess agglomeration behavior at oxygen enriched air and steam atmosphere of different feedstock in the maximum temperature up to 1050 0 C and pressure up to 10 kg/cm 2 .
  • Still another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasification facility to study entrainment behavior of different feedstock.
  • Yet another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasifier to measure gas composition, gas yield and carbon conversion during gasification for different feedstock.
  • Yet another objective of the present invention is to judge feeding behavior of different carbonaceous solids during gasification with screw feeding system in addition to rotary feeding arrangement.
  • the present invention provides an oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier comprising of heat resistant refractory lined gasifier having cylindrical vessel of two different diameters with the provision of monitoring temperature along the gasifier at five different locations, having gaseous reactant generation and supply system for the reactants like air/steam/oxygen enriched air/air-steam/oxygen enriched air-steam mixture at different proportions fitted with the provision of preheating and thorough mixing of gaseous stream before entering in to the gasifier through multiple perforation removable conical distributor and air plenum, having differential pressure measurement instrument across the distributor and bed, having fuel feeding system with lock-hopper arrangement, having multiple feeding nozzles for different fuels, having variable RPM multi-pocket rotary feeder & screw feeder, having inclined feed lines with the provision of pneumatic conveying of feed materials, having variable RPM multi-pocket rotary extractor, having provision to withdraw the ash particles either in the dry form or in agglomerated form in a controlled manner, having purging system and
  • the said gasifier is having maximum operating temperature up to 1050°C, pressure up to 10 kg/cm 2 , feed rate up to 60 kg/hour with particle size acceptability ranging between 0 - 6 mm.
  • the said gasifier is refractory lined to protect the gasifier shell at high temperature above 1100°C, having provision for temperature measurement inside the bed at two different locations and at three different locations in the free board zone.
  • Refractory lining is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle. There is also provision of measuring differential pressure across the distributor.
  • the said device having reactant (Air, Oxygen, Steam) feeding system comprising of steam generator with accumulator, air compressor with gas holder, PSA based oxygen generator, booster and header with the provision of heating of different gaseous streams up to different levels as per process requirement before entering into the gasifier including i) initial pre-heater for heating air/oxygen enriched air up to 150°C, ii) steam super heater with the capacity of heating up to 250°C, iii) initial mixture-cum-super heater with maximum heating capacity of 400°C, and iv) final mixture-cum-super heater with the capacity of heating up to 600°C.
  • reactant Air, Oxygen, Steam
  • the said device has solid fuel feeding system comprising of variable RPM multi-pocket rotary feeder and screw feeder fitted with two feed lock vessels for sequential pressurization and depressurization isolated by dome valve as well as the said system has two feed nozzles, connected to the feeder assembly with feed line having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle wide range of carbonaceous feedstock.
  • the said device has bottom ash withdrawal system comprising of Variable RPM rotary extractor and two ash lock vessels for sequential pressurization and depressurization fitted with dome valves.
  • the said device has capability to gasify single solid feed or blends of multiple feed materials as well as has nitrogen flushing arrangements for handling any kind of emergency situation.
  • the said device has high temperature cyclone system fitted with cyclone ash lock isolated by water jacketed dome valve for sequential pressurization and depressurization purpose.
  • the said device has jacketed water quench column for gas cooling and removal of suspended solids from the gas stream followed by multi compartment gravity settling tank for separation of scrubbed suspended solids from quench column water stream.
  • the said device has ventury scrubber for removal of acidic components from gas stream with the alkaline water followed by mist eliminator for removal of moisture from the gas before sampling and flaring.
  • the said device has LPG supported flare stack for flaring the excess gas stream.
  • the said device has process control and data acquisition system comprising of PLC-SCADA control station for controlling and monitoring all the process parameters along with alarm system, safety fuses, safety managements inputs for power failure, high temperature limits, sensor burnout and shorting, high flow limits, safety management outputs to terminate power to heaters.
  • process control and data acquisition system comprising of PLC-SCADA control station for controlling and monitoring all the process parameters along with alarm system, safety fuses, safety managements inputs for power failure, high temperature limits, sensor burnout and shorting, high flow limits, safety management outputs to terminate power to heaters.
  • Fig 1 represents the gasification facility comprising of various components 1-39 as embodied in the Fig 1.
  • Fig: 1 also represents PFBG Test facility consisting of various sections such as solid and gaseous reactants feeding section, gasifier section and gas cooling and cleaning section
  • Fig 2 represents PFBG Feed Nozzles and Distributor Details.
  • the present invention provides PFBG test facility consisting of various sections such as solid and gaseous reactants feeding section, gasifier section and gas cooling and cleaning section. Detailed descriptions of each section are as follow: i. Solid Feeding System
  • Feed material is introduced into the gasifier (19) through solid feeding system.
  • This system has one hopper (12) and two feed locks (14, 15).
  • the top lock is known as Feed Lockl (14) and the bottom one is Feed Lock 2 (15).
  • the top lock is used for pressurization and depressurization, in order to feed the material from Feed Lockl to Feed Lock2, which is always under pressure.
  • Solid is pneumatically fed inside the gasifier just above the bed and inside the bed by two different nozzle pipes (17, 18) using conveying air. Nitrogen flushing line with manual valve is provided with solid feeding line and feed locks for flushing/purging purpose.
  • Air/Ch Header (8) is maintained about 10 kg/cm 2 higher than that of gasifier by a pressure control valve between the air supply compressor(6) and air header. From air header, air is supplied to feed locks for pressurization, to solid transport line for conveying feed and to air heater.
  • the Oxygen pressure is maintained higher than that of the gasifier by a pressure regulator as well as oxygen booster (5) between the oxygen generator (4) and initial pre-heater (9) for pre heating prior to introducing in initial mixer - cum super-heater (10).
  • the electrically heated initial pre-heater (9) preheats air-oxygen to the required temperature. Steam is generated in a diesel fired steam generator (1) and stored in the steam accumulator (2). Steam from accumulator is passed through steam super-heater (3).
  • the Gasifier (19) is two-diameter cylindrical vessel with three zone internal refractory lining system with operating pressure up to 10 kg/cm 2 and at a temperature up to 1050 °C.
  • Refractory lining of the gasifier is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle.
  • the bottom portion of the gasifier is known as Bed Section
  • the top section of the gasifier is known as Freeboard Section
  • the third section is known as Transition piece that is conical in shape connects these two cylindrical portions.
  • Bottom of the reactor section is known as Air plenum (21), which is integrated with a conical distributor (20) and properly insulated to avoid condensation of steam.
  • the air/oxygen enriched air and steam mixture is introduced as small jets through the distributor.
  • the distributor is removable for its cleaning as and when required.
  • the height of the reactor is about 5 m including the air-steam distributor.
  • the gasifier is provided with adequate nozzles for pressure, differential pressure, temperature measurements, inside temperature measurement at five levels, bed sampling, and safety devices like pressure release valve and rupture disc. v. PFBG Feeding Nozzles
  • gasifier operates in bubbling fluidization condition and is designed to handle a wide range of carbonaceous solid feed materials like coal and different biomass having different density and reactivity and coal-biomass blends in any proportion.
  • gas - solid fluidization once a gas stream is introduced at the bottom of a packed solid bed, the gas will move upwards through the inter particle spaces. As the gas velocity exceeds a certain threshold limit called minimum fluidization velocity (t7 m f), the upward drag force turns out to be large enough to counter the particle gravity minus buoyancy. Where, the particles will move away from each other and become suspended within the fluid, causing the bed to expand in volume and show some fluid like behavior.
  • two feed nozzles (17, 18) are fitted in the gasifier at two different heights ( Figure 2).
  • One nozzle (17) is fitted just above the expanded bed at maximum possible height in view of and another nozzle is fitted above the distributor (20) at specified height, suitably to vary the bed height depending on the fuel reactivity, desired residence time, density of the feed materials and acceptable bubble diameter as discussed above.
  • placing of nozzles at different height of the gasifier is one of the key factor in order to handle wide range of feed stock successfully to get optimum level of conversion without any operational issues.
  • the ash cooler at the bottom of the air plenum (21) is a jacketed pipe. Soft water coming from spray tower flows through the jacket for cooling the hot ash.
  • a rotary ash extractor (22) located below the ash cooler extracts the ash from the reactor at a specified rate for maintaining the bed level. Below the ash extractor there are two bottom ash locks that are employed for storage of the ash, pressurization and depressurization in the reverse sequence of coal locks.
  • Ash lock vessel-I (23) is an intermediate storage vessel to hold the bottom ash when the ash lock 2 (24) is discharging the ash. Both ash lock vessel-I and ash lock vessel-II have identical capacities. Sealing/blanketing of ash locks can be done by nitrogen from nitrogen generator (7).
  • Nitrogen line with manual valve is provided on bottom ash discharge line for flushing/purging purpose in case of problems.
  • Cyclone with Fly Ash Collection System During plant operation, the raw gas from the freeboard along with elutriated fines enters cyclone (26). It is properly heat traced to prevent the condensation of condensable gases. Raw gas enters from the side and exits from the top. Ash along with un-reacted carbon particles, captured by cyclone, is collected in the cyclone ash lock (27) and then discharged. Sealing/blanketing of ash locks can be done by nitrogen from nitrogen generator. Nitrogen line with manual valve is provided on cyclone ash discharge line for flushing/purging purpose in case of problems. viii. Gas Cooling and Cleaning System
  • Gas cooling system consists of a quench Column (28) and a seal pot (29). Two concentric pipes are assembled to make the quench column. Cooled, soft water flows through its jacket coming from spray tower tank for cooling the inner shell and returns to a spray tower tank in closed loop. The cyclone exit pipe is connected at the top portion of the quench column. The inner shell has spray nozzles for spraying water and cooling the gas.
  • Quench water tank (31) is fitted with a pump (30) wherein inlet strainer of sufficient capacity is provided considering ash particles and spray nozzle openings so as to get smooth flow of water.
  • Water filtration/settling unit (32) is used for separation of particulates from the process water. The size of water filtration unit is sufficient to clean dust laden water.
  • the raw gas enters from the top of the quench column and the cooled gas along with water exits from the bottom.
  • a constant water level is maintained in quench seal pot (29).
  • the gas cleaning section also consists of a venturi scrubber (36) integrated with a venturi seal pot (35) for cleaning the acidic gas and a knock out drum/mist eliminator (37) to remove moisture from the clean gas.
  • the system consisting of alkali solution tank (34) and a circulation pump (33) for circulating alkali solution in the venturi scrubbers is also provided.
  • a small portion of the clean gas coming out of knock out drum is collected at gas sampling point (39) for gas analysis.
  • Major part of the clean gas from the knockout drum is passed through pressure regulation valve and water sealed flare stack before flaring it.
  • Flare stack (38) is provided with LPG burner as a support fuel. x. PLC-SCADA Control System
  • the said facility has control panel with data acquisition system comprising of PLC- SCADA control station along with individual heating controllers with MCBs, alarm system, safety fuses, safety managements inputs for power failure, high temperature limits, sensor burnout and shorting, high flow limits, safety management outputs to terminate power to heaters.
  • the system is completely atomized through programmable logical controller to maintain its gas flow, temperature, pressure.
  • PLC record all the parameters, all parameters trends and alarms.
  • PLC philosophy is designed to get the required graphs with respective parameters.
  • the inventive steps involved in the present invention are i.
  • the oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier of 1.5 TPD feed capacity is to gasify the coal; biomass; washery rejects; and their blends in any proportion in the actual atmosphere with continuous feeding and ash withdrawal, essential in the commercial gasifier to ensure combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications.
  • the Gasifier is two-diameter cylindrical vessel comprising of bed section, freeboard section and in between transition section which ensures sufficient residence time of the generated syngas at high temperature to produce tar-free syngas from different feedstock as well as minimum fine elutriation.
  • the system is equipped in such a way that it can be operated in air/ oxygen/oxygen enriched air/ steam as well as their mixture in any proportion as per process requirement.
  • Refractory lined gasifier is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle.
  • the said device has solid fuel feeding system comprising of variable RPM multipocket rotary feeder, screw feeder and two feed nozzles connected to the feeder assembly with feed line having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle wide range of carbonaceous feedstock. Further, while one nozzle is being used for feeding, the other may be used for bed sampling during the experimental run. vi.
  • Present device has removable air plenum section of multiple distributors with varying number and sizes of orifices to adjust reactant velocity and flow during endothermic gasification reactions as per the physic-chemical properties of different feedstock.
  • Removable air plenum has the advantages of easy cleaning and maintenance of the distributor plate leading to smooth and trouble free operation.
  • Present device has the Provision of Nitrogen flushing arrangement in the entire system to tackle any kind of emergency situation during operation. Inflow of nitrogen dilutes reactant components in the gasifier to stop sudden temperature shoot up to prevent ash agglomeration and clinker formation inside the gasifier.
  • Present device has wide range of operational flexibility with respect to pressure, temperature, feed rate of fuel and gaseous reactant, residence time, bed inventory, particle size and particle density.
  • inert bed material coal ash -2 mm
  • bed material is transferred from the atmospheric hopper to feed lock-I and then from feed lock- I to lock-II.
  • inert bed material at the desired mass flow rate is fed from lock II to the bed section of the gasifier using a rotary feeder through a pneumatic conveying line to build up the bed of desired height.
  • Preheated air, air-oxygen and steam are mixed and superheated up to 550°C in an air-steam mixer and admitted to the gasifier through the conical distributor at a controlled rate to maintain proper fluidization as well as to fulfill the process requirement.
  • Inert bed material from the bed is extracted under controlled rate to maintain the desired bed height and cooled to about 55°C prior to discharging in bottom ash lock-I and then lock II.
  • Bed height is monitored through differential pressure transmitters and maintained as per the process requirement.
  • the bottom ash is collected at the interval of 15 minutes with controlled rate using rotary extractor.
  • discharge temperature, reactor temperature, weight of the bottom ash, differential pressure and the time of discharge collection are noted down.
  • the feed rate and ash discharge rate are maintained constant after the completion of bed build up.
  • feed sample i.e. coal/biomass/rejects or their blended composition of the desired range are fed to the gasifier.
  • fuel inside bed start ignition and temperature is gradually raised up to 950-1050 °C with care so as to avoid any kind of agglomeration/clinker formation inside the bed.
  • bed temperature is slowly raised up to desired temperature. Bottom ash samples are collected at regular intervals and kept for further analysis.
  • the hot dusty raw fuel gases leave gasifier from freeboard section and enter into the cyclone where most of the elutriated particles are captured.
  • the captured particles are discharged in cyclone ash lock.
  • the fuel gas from the cyclone enters into the Quench Column.
  • the water from the process water tank is directly sprayed onto the gas to reduce the temperature and capture the residual solid particles.
  • the Quench Column is water jacketed and cold water is circulated in a closed loop, drawing water from Cooling Tower.
  • the cooled gas along with sprayed water comes in the Seal Pot situated at the bottom of the quench pipe.
  • the level of water in Seal Pot is maintained by controlling the rate of water discharge to water filtration unit.
  • the clean water from the water filtration unit is recycled back to the process water tank.
  • the cooled gas exits from the top side of the seal pot and enters into venturi scrubber where fuel gas is further treated with recirculation of alkaline water to remove the acidic components.
  • the saturated clean gas, containing water droplets then passes through knock out drum to get all the moisture removed from the clean gas.
  • One part of the clean gas coming out of knock out drum is collected for gas analysis on regular basis and other part of clean gas under pressure from the knockout drum is passed through pressure regulation valve and water sealed flare stack before flaring it.
  • Flare stack is provided with LPG burner as a support fuel.
  • the collected gas samples are analyzed using the off line Gas Chromatograph to get the gas composition.
  • the gas composition basically comprises of carbon monoxide, hydrogen, carbon dioxide and methane.
  • Experimental conditions and product gas compositions of three experimental runs with two Coal from different mines i.e. MCL-I, MCL-II are shown in Table 1 and Table 2, respectively.
  • the oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier of 1.5 TPD feed capacity is equipped in such a way that it can be operated in air/ oxygen/oxygen enriched air/ steam as well as their mixture in any proportion as per process requirement. Gasification performance of a particular feed material can be judged in this test facility within a short span of time for its commercial exploitation.
  • the said system has distinct advantages of having solid fuel feeding system comprising of variable RPM multi-pocket rotary feeder, screw feeder and two feed nozzles connected to the feeder assembly having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle coal; biomass; washery rejects; and their blends in any proportion in the actual atmosphere which prevails in the commercial gasifier ensuring combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications. Further, while one nozzle is being used for feeding, the other may be used for bed sampling during the experimental run.
  • Freeboard section of the refractory lined gasifier is of sufficient length to ensure desired residence time of the generated syngas at high temperature to produce tar-free syngas from different feedstock as well as minimum fine elutriation.
  • Refractory lining of the gasifier is designed in such a way that it can withstand the pressure, temperature, minimize the erosion and heat loss as well as the expansion and contraction during heating and cooling cycle.
  • the said system is having advantages of reactant feeding system comprising of steam generator with accumulator, air compressor with gas holder, PSA based oxygen generator, booster and header with the provision of heating of different gaseous streams in the range of 150 - 600 °C as per process requirement before entering into the gasifier depending on the combustibility and gasification characteristics of different carbonaceous feedstock.
  • Present device has advantage to withdraw the ash particles either in the dry form or in agglomerated form in a controlled manner.
  • Present system has removable air plenum section of multiple distributors with varying number and sizes of orifices to adjust reactant velocity and flow during endothermic gasification reactions.
  • Removable air plenum has the advantages of easy cleaning and maintenance of the distributor leading to smooth and trouble free operation.
  • Present device has the Provision of Nitrogen flushing arrangement in the entire system to tackle any kind of emergency situation during operation. Inflow of nitrogen dilutes reactant components in the gasifier to stop sudden temperature shoot up which may cause ash agglomeration and clinker formation inside the gasifier.
  • Present device has wide range of operational flexibility with respect to pressure, temperature, feed rate of fuel and gaseous reactant, residence time, particle size and particle density.
  • the present system has also arrangement for product gas analysis with the help of on-line gas analyzer coupled with the system in exit line or provision for collecting the outgoing gas from the sampling port with the help of any gas sampling arrangement for off-line gas analysis purpose

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Abstract

The present invention discloses oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier of 1.5 TPD feed capacity to gasify coal, biomass, washery rejects, and their blends in any proportion in the actual atmosphere of commercial gasifier. The system is equipped in such a way that it can be operated in air/ oxygen/oxygen enriched air/ steam as well as their mixture in any proportion as per process requirement. The present invention discloses gasifier having feed rate carrying capacity up to 60 kg/hour, maximum operating temperature up to 1050°C and pressure up to 10 kg/cm2. The facility consists different sections for gaseous and solid feeding, gasification, ash withdrawal, and gas Cooling & Cleaning. Besides gasification performance analysis, present invention is also discloses the study of agglomeration characteristics, entrainment and other fluidized bed gasification related parameters.

Description

AN OXYGEN ENRICHED AIR BLOWN PILOT SCALE PRESSURIZED FLUIDIZED BED REFRACTORY LINED GASIFIER
FIELD OF THE INVENTION
The present invention relates to a development of oxygen enriched air blown pressurized fluidized bed pilot scale gasifier to evaluate gasification performance of coal, biomass, washery rejects and their blends in any proportion. More particularly, the present invention relates to an oxygen enriched air blown pressurized fluidized bed gasification pilot scale facility with refractory lined gasifier having feed rate carrying capacity up to 60 kg/hour, maximum operating temperature up to 1050°C and pressure up to 10 kg/cm2. The facility consists of gaseous and solid feeding section, gasification section, ash withdrawal section, and gas Cooling & Cleaning section. Besides gasification performance analysis, this invention is also to study agglomeration characteristics, entrainment and other fluidized bed gasification related parameters.
BACK GROUND OF THE INVENTION
India has a vast reserve of coal dominating inferior grade high ash non-coking coal. The high ash content of Indian coal is a crucial barrier in the development of suitable technology. Among the available gasification technologies, the Entrained flow gasifier is a matured one but not recommended for high ash coal due to its enormous heat loss and thermal imbalance associated with the outgoing molten slag. Fixed bed gasification technology is restricted up to the coal of 30% ash, at the same time it creates a significant amount of hazardous tar requiring a large amount of capital investment for the downstream processing. As such utilization of high ash coal by the aforementioned technologies imply economic and environmental penalties in terms of feed beneficiation and downstream processing for various applications such as, power, chemicals, fertilizer, DRI as well as thermal. With these S&T challenges, fluidized bed gasifier is capable to gasify wide range of feedstock. It is most suitable to utilize high ash coal without beneficiation for reducing ash level as well as efficient to handle not only biomass but also washery rejects and their blends in any proportion for different applications with negligible tar formation leading to the reasonably reduction of downstream CAPEX & OPEX. In a fluidized bed gasifier, the heat transfer between gas and solid phases is better owing to the fluid like behavior of the reactants. However, high ash coals have number of disadvantages like low heat value, operational constraints, low efficiency etc. Agglomeration of ash particles may lead to defluidization of the bed which results in the shutdown of the plant due to inherent properties of some feedstock. Therefore, it is necessary to study the gasification behavior of the particular coal, biomass, washery rejects and their blends in fluidized bed gasifier to judge its suitability. With this background present invention, development of oxygen enriched air blown pressurized fluidized bed gasification pilot scale facility with refractory lined gasifier becomes relevant.
Reference may be made to United States Patent No. 4,968,325 by Black, et al. dated November 6, 1990 wherein authors have disclosed a process and a plant for gasifying biomass. The plant has a pressure vessel containing a hot fluidized sand bed. The biomass is pre-dried to a moisture content of 10% to 35% by weight. A steam-free oxygencontaining gas is fed and distributed, through a grid system at the bottom of the hot sand bed, to hold the bed in a fluidized state and to form, in its lower portion, an oxygen-rich heat-forming combustion zone and, in its upper portion, a hydrogen-rich gas-forming pyrolysis zone. The pre-dried biomass is uninterruptedly fed in the pyrolysis zone at essentially the center of the hot fluidized bed, this center being determined when the sand bed stands at rest. The fluidized bed is held at an operating temperature of 750 to 860oC. under an operating pressure of 400 kPa to 1750 kPa by controlling the feeding rate of the fluidized gas as well as the feeding rate of the biomass. The gases and biomass residue released from the hot fluidized bed are removed in a gas stream from the head space above the bed and sent to a primary cyclone which separates the useful gases from most of the biomass residue the latter being returned to the combustion zone of the bed. The gases and the biomass residue that have remained in the first cyclone are then moved into a second cyclone where the useful gases are collected and the biomass residue discarded. The drawbacks are;
• This system is utilized only for Biomass.
• Maximum temperature is up to 860°C only.
• Provision for removal of acidic components from the gas is not available. Provision of pre-heating and through missing of gaseous reactants before entering into the gasifier is not available.
No Provision of on line gas analysis system.
Yet another reference is made to United States Patent No. 4,490,157 by Fernandes dated December 25, 1984 wherein authors have described indirectly heated fluidized bed gasifier. A fluidized bed gasifier for gasifying a fuel, first receives heat indirectly from a combusting fluidized bed disposed at least partially within the gasifier fluidized bed. Fuel for the combusting bed may be provided by removing a portion of the fluidized fuel from the gasifier bed and transporting this removed portion into the combusting bed. Heat is transferred across the conductive walls of the combustor vessel. Product gas heating value is increased by separately removing the products of combustion from the gasifier and by recycling a portion of the product fuel gas as the fluidizing gas for the gasifier fluidized bed. A radiation shield is also provided to reduce heat loss from the gasifier bed and to remove elutriated material from the product fuel gas. The drawbacks are:
• Heat transfer from combustion zone to gasification zone takes place only through conductive wall placed between two zones.
• Provision of pre-heating and thorough missing of gaseous reactants before entering into the gasifier is not available.
• No Provision of on line gas analysis system.
• System seems to be complicated considering the fabrication and operation.
Yet another reference is made to United States Patent No. 9,181,502 B2 by July 8, 2013, wherein authors have disclosed a two-stage fluidized bed gasification system for high ash, high ash fusion temperature bituminous coal, first stage gasifier is a circulating fluidized bed transport gasifier operating in the temperature range of approximately 900°C to 1100°C, second stage gasifier is a fluidized bed partial oxidizer operating in the temperature range of approximately 1100°C to 1400°C. The first stage gasifier serves as a primary gasifier converting up to 90% of carbon to syngas components along with some tar. The residual char carbon and tar from the gasifier is then thermally cracked and converted to syngas components in a second stage high temperature fluidized bed oxidizer. The two-step process can achieve over approximately 98% overall carbon conversion to syngas components. However, the system is only for high ash, high ash fusion temperature bituminous coal as well as system seems to be complicated considering the fabrication and operation. Also there is no provision of on line gas analysis of the product gas.
Yet another reference is made to Patent Application No. CN201610944225, wherein the invention discloses a technique for carrying out coal gasification by a bubbling fluidized bed. The technique comprises the following steps like, coal grinding and drying; coal pressurization and coal feeding; coal gasification; crude de-dusting by cyclone separation; waste heat recovery; synthetic gas deep de-dusting and purification; and clinker treatment. However, the system is only for coal gasification. Other feed materials like biomass/ coalbiomass blends cannot be utilized in the system. There is also no provision of online gas analysis system.
Yet another reference is made to United States Patent Application Number US05868959, wherein the invention relates to methods of operating fluidized bed systems combining a dense fluidized bed and an entrained fluidized bed wherein the beds contain particle components having long-term chemical and physical stability in the system, one particle component being retained in the dense fluidized bed while the other is entrained and recirculated through a portion of the dense bed to increase residence time and promote more complete reaction of the reactant feed particles therein. In particular, the invention relates to the operation of such a multi-solid system wherein the dense bed is operated with two distinct temperature zones for optimum control of a fuel combustion or gasification and capture of released sulfur by an added sorbent. With slight modification, the method is utilized for both combustion and gasification of high-sulfur coal. However, this is a circulating fluidized bed type and is used for coal only. Operation of the device is complicated too particularly to maintain two reaction zones inside the reactor.
Yet another reference is made to United States Patent Application Number US 10451727, wherein the invention relates to a method and apparatus for effectively utilizing thermal energy possessed by a high-temperature combustion gas discharged from a combustor and utilizing high-temperature oxygen contained in the high-temperature combustion gas discharged from the combustor. A fluidized-bed gasification apparatus for gasifying combustibles in a fluidized-bed furnace comprises a gasification furnace for gasifying combustibles therein and a combustion furnace for combusting combustible components therein. The fluidized medium moves between the gasification furnace and the combustion furnace, and exhaust gas discharged from another combustor is utilized as a fluidizing gas in the combustion furnace. This is working in the principle of dual fluidized bed. No provision of online gas analysis, pre-heating of the reactants. Working principle is also complicated.
Yet another reference is made to publication by Engelbrecht et al. (Industrial Fluidization South Africa: pages 145 - 160. Edited by A. Luckos & P. den Hoed Johannesburg: Southern African Institute of Mining and Metallurgy, 2011) wherein the authors have reported fluidized bed gasification of high ash South African coal in a pilot scale bubbling fluidized bed gasifier having capacity of 15-35 kg/hour coal feed rate at atmospheric pressure. The coal feeding/extraction is done with the help of screw feeder. However, the system is developed for coal gasification only and there is no provision of dual feeding arrangement comprising of rotary feeder and screw feeder.
Yet another reference is made to publication by Kumar et al. (Applied Thermal Engineering, Vol.116, pages 372 - 381, 2017), wherein the authors have conducted gasification of high ash coal in a bubbling fluidized bed gasifier. The gasifier has height of 2.5 meter, and single diameter throughout the height with refractory lining. Screw feeder is used to feed the coal particles in the gasifier and also there is no provision of dual feeding system comprising of rotary feeder and screw feeder. Gaseous reactant feeding system also lack of pre-heating and thorough mixing before entering into the gasifier.
Yet another reference is made to Indian Patent Application Number 201811014119, wherein the invention relates to a Pressurized Fluidized Bed Gasification (PFBG) Pilot Scale Test Facility with the provision of external heating to test the high ash coals, biomass, rejects and their blends. More particularly, this invention relates to an air- blown Pressurized Fluidized Bed Gasification (PFBG) pilot scale Test Facility having feed rate carrying capacity varying from 7 kg/hour to 20 kg/hour. It has maximum operating temperature up to 1000°C and pressure up to 3 kg/cm2. The test facility consists of externally heated metallic pressurized fluidized bed gasifier. However, the system does not have refractory lined gasifier. The gasifier is not capable to conduct gasification performance analysis in oxygen-steam mixture as it not equipped with oxygen generator. There is also no provision of dual feeding arrangement comprising of rotary feeder and screw feeder.
All the inventions as stated above describe specific designs and related process corresponding to different kinds of fluidized bed gasification setup having limited flexibility to feed material and operating conditions, whereas for further development in this emerging area towards developing suitable gasifier capable to handle different kinds of feed materials has become essential. The current gasification facility is having potentiality to establish desired hydrodynamics to enhance the gasification performance like gas composition, gas yield, carbon conversion and related parameters for different feedstock.
OBJECTIVES OF THE INVENTION
Based on the prior art details and drawbacks thereof, the main objective of the present invention is to develop oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier to evaluate gasification performance of coal, biomass, washery rejects, and their blends in any proportion in the actual atmosphere which prevails in the commercial gasifier including combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications which obviates the drawbacks of the hitherto known prior art as detailed above.
Another objective of the present invention is to develop oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier to evaluate gasification performance of coal, biomass, washery rejects, and their blends in any proportion in air/ oxygen/oxygen enriched air/ steam as well as their mixture of any ratio as per process requirement.
Yet another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasifier to assess agglomeration behavior at oxygen enriched air and steam atmosphere of different feedstock in the maximum temperature up to 10500 C and pressure up to 10 kg/cm2.
Still another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasification facility to study entrainment behavior of different feedstock.
Yet another objective of the present invention is to develop pilot scale oxygen enriched air blown pressurized fluidized bed gasifier to measure gas composition, gas yield and carbon conversion during gasification for different feedstock.
Yet another objective of the present invention is to judge feeding behavior of different carbonaceous solids during gasification with screw feeding system in addition to rotary feeding arrangement.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides an oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier comprising of heat resistant refractory lined gasifier having cylindrical vessel of two different diameters with the provision of monitoring temperature along the gasifier at five different locations, having gaseous reactant generation and supply system for the reactants like air/steam/oxygen enriched air/air-steam/oxygen enriched air-steam mixture at different proportions fitted with the provision of preheating and thorough mixing of gaseous stream before entering in to the gasifier through multiple perforation removable conical distributor and air plenum, having differential pressure measurement instrument across the distributor and bed, having fuel feeding system with lock-hopper arrangement, having multiple feeding nozzles for different fuels, having variable RPM multi-pocket rotary feeder & screw feeder, having inclined feed lines with the provision of pneumatic conveying of feed materials, having variable RPM multi-pocket rotary extractor, having provision to withdraw the ash particles either in the dry form or in agglomerated form in a controlled manner, having purging system and rupture disc/safety valve, having cyclone separator, quench column, ventury scrubber, mist eliminator, settling tank, gas sampling station and flare stack enabling wide range of operational flexibility with respect to pressure, temperature, feedstock, feed rate, gaseous reactant, residence time, particle size and particle density.
In an embodiment of the invention, the said gasifier is having maximum operating temperature up to 1050°C, pressure up to 10 kg/cm2, feed rate up to 60 kg/hour with particle size acceptability ranging between 0 - 6 mm.
In another embodiment of the invention, the said gasifier is refractory lined to protect the gasifier shell at high temperature above 1100°C, having provision for temperature measurement inside the bed at two different locations and at three different locations in the free board zone. Refractory lining is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle. There is also provision of measuring differential pressure across the distributor.
In another embodiment of the invention, the said device having reactant (Air, Oxygen, Steam) feeding system comprising of steam generator with accumulator, air compressor with gas holder, PSA based oxygen generator, booster and header with the provision of heating of different gaseous streams up to different levels as per process requirement before entering into the gasifier including i) initial pre-heater for heating air/oxygen enriched air up to 150°C, ii) steam super heater with the capacity of heating up to 250°C, iii) initial mixture-cum-super heater with maximum heating capacity of 400°C, and iv) final mixture-cum-super heater with the capacity of heating up to 600°C.
In yet another embodiment of the invention, the said device has solid fuel feeding system comprising of variable RPM multi-pocket rotary feeder and screw feeder fitted with two feed lock vessels for sequential pressurization and depressurization isolated by dome valve as well as the said system has two feed nozzles, connected to the feeder assembly with feed line having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle wide range of carbonaceous feedstock.
In still another embodiment of the invention, the said device has bottom ash withdrawal system comprising of Variable RPM rotary extractor and two ash lock vessels for sequential pressurization and depressurization fitted with dome valves.
In yet another embodiment of the invention, the said device has capability to gasify single solid feed or blends of multiple feed materials as well as has nitrogen flushing arrangements for handling any kind of emergency situation.
In yet another embodiment of the invention, the said device has high temperature cyclone system fitted with cyclone ash lock isolated by water jacketed dome valve for sequential pressurization and depressurization purpose.
In yet another embodiment of the invention, the said device has jacketed water quench column for gas cooling and removal of suspended solids from the gas stream followed by multi compartment gravity settling tank for separation of scrubbed suspended solids from quench column water stream.
In still another embodiment of the invention, the said device has ventury scrubber for removal of acidic components from gas stream with the alkaline water followed by mist eliminator for removal of moisture from the gas before sampling and flaring.
In still another embodiment of the invention, the said device has LPG supported flare stack for flaring the excess gas stream.
In yet another embodiment of the invention, the said device has process control and data acquisition system comprising of PLC-SCADA control station for controlling and monitoring all the process parameters along with alarm system, safety fuses, safety managements inputs for power failure, high temperature limits, sensor burnout and shorting, high flow limits, safety management outputs to terminate power to heaters. BRIEF DESCRIPTION OF THE DRAWING
In the drawing accompanying the specification, Fig 1 represents the gasification facility comprising of various components 1-39 as embodied in the Fig 1.
I. Boiler (Steam Generator); 2. Steam Accumulator; 3. Steam Super-Heater 4. Oxygen Generator; 5. Oxygen Booster; 6.Air Compressor; 7. Nitrogen Generator; 8.Reactant Process Header/Hopper; 9.Reactant Pre-Heater; lO.Reactant Mixer-Cum-Super-Heater-I;
I I.Reactant Mixer-Cum-Super-Heater-II; 12.Feed Hooper; 13.Dome valve and Actuated Ball Valve; 14.Feed Lock Vessel-I; 15.Feed Lock Vessel-II; 16.A Rotary Feeder; 16.B Screw Feeder; 17. Feed Nozzle-I; 18.Feed Nozzle-II ; 19. Gasifier; 20.Conical Distributor; 2LAir Plenum; 22.Rotary Extractor; 23.Ash Lock Vessel-I; 24.Ash Lock Vessel-II; 25.Thermocouple; 26.Cyclone Separator; 27.Cyclone Ash Lock; 28. Quench Column; 29. Quench Seal Pot; 3O.Quench Water Circulation Pump; 31. Quench Water Tank; 32.Settling Tank; 33.Alkaline Solution Recirculation Pump; 34.Alkaline Solution Tank; 35.Ventury Alkaline Solution Seal Pot; 36. Ventury Scrubber; 37. Knockout Drum (Mist Eliminator); 38.Flare stack; 39. Gas sampling port. Further, Fig: 1 also represents PFBG Test facility consisting of various sections such as solid and gaseous reactants feeding section, gasifier section and gas cooling and cleaning section
Fig 2 represents PFBG Feed Nozzles and Distributor Details.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides PFBG test facility consisting of various sections such as solid and gaseous reactants feeding section, gasifier section and gas cooling and cleaning section. Detailed descriptions of each section are as follow: i. Solid Feeding System
Feed material is introduced into the gasifier (19) through solid feeding system. This system has one hopper (12) and two feed locks (14, 15). The top lock is known as Feed Lockl (14) and the bottom one is Feed Lock 2 (15). The top lock is used for pressurization and depressurization, in order to feed the material from Feed Lockl to Feed Lock2, which is always under pressure. The Rotary feeder (16 A) for coal/coal-biomass blends and Screw Feeder (16B) for biomass and like material control feed rate. Solid is pneumatically fed inside the gasifier just above the bed and inside the bed by two different nozzle pipes (17, 18) using conveying air. Nitrogen flushing line with manual valve is provided with solid feeding line and feed locks for flushing/purging purpose. It may be mentioned here that there are two feed nozzles (17, 18) provided in the gasifier to introduce different feeds in the gasifier. This arrangement helps to change the inclination of the feed lines for smooth flow of the feed materials of different densities. Further, while one nozzle is being used for feeding, the other may be used for bed sampling during the experimental run. ii. Gaseous Reactant Supply System
The pressure of Air/Ch Header (8) is maintained about 10 kg/cm2 higher than that of gasifier by a pressure control valve between the air supply compressor(6) and air header. From air header, air is supplied to feed locks for pressurization, to solid transport line for conveying feed and to air heater. The Oxygen pressure is maintained higher than that of the gasifier by a pressure regulator as well as oxygen booster (5) between the oxygen generator (4) and initial pre-heater (9) for pre heating prior to introducing in initial mixer - cum super-heater (10). The electrically heated initial pre-heater (9) preheats air-oxygen to the required temperature. Steam is generated in a diesel fired steam generator (1) and stored in the steam accumulator (2). Steam from accumulator is passed through steam super-heater (3). These air-oxygen and steam are further introduced in initial mixer-cum- super-heater (10) and final mixer-cum-super-heater (11). Both the mixer-cum-super- heater-initial and final are used for mixing and super heating the air-oxygen-steam stream before admitting to the reactor. The Mass flow meters and flow control valves are provided to regulate airflow rates and oxygen flow rates in fluidizing air-line, oxygen line, and the transport line. Mass flow meter, flow controller and flow control valves regulate steam flow rate. All lines from steam generator and heater to reactor are thermal heat insulated. Nitrogen line with manual valve is provided on gaseous reactant feed line for flushing/purging purpose in case of any sort of emergency. iii. Gasifier iv. The Gasifier (19) is two-diameter cylindrical vessel with three zone internal refractory lining system with operating pressure up to 10 kg/cm2 and at a temperature up to 1050 °C. Refractory lining of the gasifier is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle. There is also provision of measuring differential pressure across the distributor. The bottom portion of the gasifier is known as Bed Section, the top section of the gasifier is known as Freeboard Section and the third section is known as Transition piece that is conical in shape connects these two cylindrical portions. Bottom of the reactor section is known as Air plenum (21), which is integrated with a conical distributor (20) and properly insulated to avoid condensation of steam. The air/oxygen enriched air and steam mixture is introduced as small jets through the distributor. The distributor is removable for its cleaning as and when required. The height of the reactor is about 5 m including the air-steam distributor. The gasifier is provided with adequate nozzles for pressure, differential pressure, temperature measurements, inside temperature measurement at five levels, bed sampling, and safety devices like pressure release valve and rupture disc. v. PFBG Feeding Nozzles
In the present case gasifier operates in bubbling fluidization condition and is designed to handle a wide range of carbonaceous solid feed materials like coal and different biomass having different density and reactivity and coal-biomass blends in any proportion. In case of gas - solid fluidization, once a gas stream is introduced at the bottom of a packed solid bed, the gas will move upwards through the inter particle spaces. As the gas velocity exceeds a certain threshold limit called minimum fluidization velocity (t7mf), the upward drag force turns out to be large enough to counter the particle gravity minus buoyancy. Where, the particles will move away from each other and become suspended within the fluid, causing the bed to expand in volume and show some fluid like behavior. As the gas velocity is further increased, the bed will keep expanding resulting in increase in bed height, reduction in the bulk density and finally entrainment wherein the particles will get carried away from the bed with the gas stream. Further, expanded bed and higher the bed height provides increase in volume of the fluidizing bed resulting in higher residence time of the particle inside the bed and subsequently higher carbon conversion. On the contrary, once gas bubble detaches from distributor hole and travels inside fluidizing bed, its diameter increases with height causing reduction in gas-particle contact and increase in probability of entrainment, thus restricting maximum bed height at certain level. Further, when the fuel particle has lower reactivity, higher residence time is required to achieve the desired level of conversion. Simultaneously, lower density materials occupies more volume requiring more bed height to accommodate desired holdup. In the present setup, to adjust the bed height in desired range, two feed nozzles (17, 18) are fitted in the gasifier at two different heights (Figure 2). One nozzle (17) is fitted just above the expanded bed at maximum possible height in view of and another nozzle is fitted above the distributor (20) at specified height, suitably to vary the bed height depending on the fuel reactivity, desired residence time, density of the feed materials and acceptable bubble diameter as discussed above. Thus, placing of nozzles at different height of the gasifier is one of the key factor in order to handle wide range of feed stock successfully to get optimum level of conversion without any operational issues. vi. Bottom Ash Extraction System
The ash cooler at the bottom of the air plenum (21) is a jacketed pipe. Soft water coming from spray tower flows through the jacket for cooling the hot ash. A rotary ash extractor (22) located below the ash cooler extracts the ash from the reactor at a specified rate for maintaining the bed level. Below the ash extractor there are two bottom ash locks that are employed for storage of the ash, pressurization and depressurization in the reverse sequence of coal locks. Ash lock vessel-I (23) is an intermediate storage vessel to hold the bottom ash when the ash lock 2 (24) is discharging the ash. Both ash lock vessel-I and ash lock vessel-II have identical capacities. Sealing/blanketing of ash locks can be done by nitrogen from nitrogen generator (7). Nitrogen line with manual valve is provided on bottom ash discharge line for flushing/purging purpose in case of problems. vii. Cyclone with Fly Ash Collection System During plant operation, the raw gas from the freeboard along with elutriated fines enters cyclone (26). It is properly heat traced to prevent the condensation of condensable gases. Raw gas enters from the side and exits from the top. Ash along with un-reacted carbon particles, captured by cyclone, is collected in the cyclone ash lock (27) and then discharged. Sealing/blanketing of ash locks can be done by nitrogen from nitrogen generator. Nitrogen line with manual valve is provided on cyclone ash discharge line for flushing/purging purpose in case of problems. viii. Gas Cooling and Cleaning System
Gas cooling system consists of a quench Column (28) and a seal pot (29). Two concentric pipes are assembled to make the quench column. Cooled, soft water flows through its jacket coming from spray tower tank for cooling the inner shell and returns to a spray tower tank in closed loop. The cyclone exit pipe is connected at the top portion of the quench column. The inner shell has spray nozzles for spraying water and cooling the gas. Quench water tank (31) is fitted with a pump (30) wherein inlet strainer of sufficient capacity is provided considering ash particles and spray nozzle openings so as to get smooth flow of water. Water filtration/settling unit (32) is used for separation of particulates from the process water. The size of water filtration unit is sufficient to clean dust laden water. The raw gas enters from the top of the quench column and the cooled gas along with water exits from the bottom. A constant water level is maintained in quench seal pot (29). The gas cleaning section also consists of a venturi scrubber (36) integrated with a venturi seal pot (35) for cleaning the acidic gas and a knock out drum/mist eliminator (37) to remove moisture from the clean gas. The system consisting of alkali solution tank (34) and a circulation pump (33) for circulating alkali solution in the venturi scrubbers is also provided. ix. Exhaust System and Flare Stack
A small portion of the clean gas coming out of knock out drum is collected at gas sampling point (39) for gas analysis. Major part of the clean gas from the knockout drum is passed through pressure regulation valve and water sealed flare stack before flaring it. Flare stack (38) is provided with LPG burner as a support fuel. x. PLC-SCADA Control System
The said facility has control panel with data acquisition system comprising of PLC- SCADA control station along with individual heating controllers with MCBs, alarm system, safety fuses, safety managements inputs for power failure, high temperature limits, sensor burnout and shorting, high flow limits, safety management outputs to terminate power to heaters. The system is completely atomized through programmable logical controller to maintain its gas flow, temperature, pressure. PLC record all the parameters, all parameters trends and alarms. PLC philosophy is designed to get the required graphs with respective parameters.
The inventive steps involved in the present invention are i. The oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier of 1.5 TPD feed capacity is to gasify the coal; biomass; washery rejects; and their blends in any proportion in the actual atmosphere with continuous feeding and ash withdrawal, essential in the commercial gasifier to ensure combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications. ii. The Gasifier is two-diameter cylindrical vessel comprising of bed section, freeboard section and in between transition section which ensures sufficient residence time of the generated syngas at high temperature to produce tar-free syngas from different feedstock as well as minimum fine elutriation. iii. The system is equipped in such a way that it can be operated in air/ oxygen/oxygen enriched air/ steam as well as their mixture in any proportion as per process requirement. iv. Refractory lined gasifier is designed in such a way that it can withstand the pressure, minimize the erosion at high temperature as well as the expansion and contraction during heating and cooling cycle. v. The said device has solid fuel feeding system comprising of variable RPM multipocket rotary feeder, screw feeder and two feed nozzles connected to the feeder assembly with feed line having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle wide range of carbonaceous feedstock. Further, while one nozzle is being used for feeding, the other may be used for bed sampling during the experimental run. vi. Present device has removable air plenum section of multiple distributors with varying number and sizes of orifices to adjust reactant velocity and flow during endothermic gasification reactions as per the physic-chemical properties of different feedstock. Removable air plenum has the advantages of easy cleaning and maintenance of the distributor plate leading to smooth and trouble free operation. vii. Present device has the Provision of Nitrogen flushing arrangement in the entire system to tackle any kind of emergency situation during operation. Inflow of nitrogen dilutes reactant components in the gasifier to stop sudden temperature shoot up to prevent ash agglomeration and clinker formation inside the gasifier. viii. Present device has wide range of operational flexibility with respect to pressure, temperature, feed rate of fuel and gaseous reactant, residence time, bed inventory, particle size and particle density.
EXAMPLE
The following example is given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
At first, the power supply and water supply is checked before switch on the plant. Required quantity of inert bed material (coal ash -2 mm) is taken in the feed hopper and then bed material is transferred from the atmospheric hopper to feed lock-I and then from feed lock- I to lock-II. Then inert bed material at the desired mass flow rate is fed from lock II to the bed section of the gasifier using a rotary feeder through a pneumatic conveying line to build up the bed of desired height. Preheated air, air-oxygen and steam are mixed and superheated up to 550°C in an air-steam mixer and admitted to the gasifier through the conical distributor at a controlled rate to maintain proper fluidization as well as to fulfill the process requirement. Inert bed material from the bed is extracted under controlled rate to maintain the desired bed height and cooled to about 55°C prior to discharging in bottom ash lock-I and then lock II. Bed height is monitored through differential pressure transmitters and maintained as per the process requirement. The bottom ash is collected at the interval of 15 minutes with controlled rate using rotary extractor. At the same time, discharge temperature, reactor temperature, weight of the bottom ash, differential pressure and the time of discharge collection are noted down. The feed rate and ash discharge rate are maintained constant after the completion of bed build up.
After attaining bed temperature of 500°C and stabilization of the entire system, feed sample i.e. coal/biomass/rejects or their blended composition of the desired range are fed to the gasifier. Then fuel inside bed start ignition and temperature is gradually raised up to 950-1050 °C with care so as to avoid any kind of agglomeration/clinker formation inside the bed. Further, bed temperature is slowly raised up to desired temperature. Bottom ash samples are collected at regular intervals and kept for further analysis.
The hot dusty raw fuel gases leave gasifier from freeboard section and enter into the cyclone where most of the elutriated particles are captured. The captured particles are discharged in cyclone ash lock.
The fuel gas from the cyclone enters into the Quench Column. The water from the process water tank is directly sprayed onto the gas to reduce the temperature and capture the residual solid particles. There are Spray Nozzles that are placed at regular heights. The Quench Column is water jacketed and cold water is circulated in a closed loop, drawing water from Cooling Tower. The cooled gas along with sprayed water comes in the Seal Pot situated at the bottom of the quench pipe. The level of water in Seal Pot is maintained by controlling the rate of water discharge to water filtration unit. The clean water from the water filtration unit is recycled back to the process water tank.
The cooled gas exits from the top side of the seal pot and enters into venturi scrubber where fuel gas is further treated with recirculation of alkaline water to remove the acidic components. The saturated clean gas, containing water droplets then passes through knock out drum to get all the moisture removed from the clean gas. One part of the clean gas coming out of knock out drum is collected for gas analysis on regular basis and other part of clean gas under pressure from the knockout drum is passed through pressure regulation valve and water sealed flare stack before flaring it. Flare stack is provided with LPG burner as a support fuel. The collected gas samples are analyzed using the off line Gas Chromatograph to get the gas composition. The gas composition basically comprises of carbon monoxide, hydrogen, carbon dioxide and methane. Experimental conditions and product gas compositions of three experimental runs with two Coal from different mines i.e. MCL-I, MCL-II are shown in Table 1 and Table 2, respectively.
Table 1: Experimental Conditions
Figure imgf000020_0001
Table 2: Syngas Compositions
Figure imgf000020_0002
ADVANTAGES OF THE INVENTION
1. The oxygen enriched air blown pressurized fluidized bed pilot scale refractory lined gasifier of 1.5 TPD feed capacity is equipped in such a way that it can be operated in air/ oxygen/oxygen enriched air/ steam as well as their mixture in any proportion as per process requirement. Gasification performance of a particular feed material can be judged in this test facility within a short span of time for its commercial exploitation.
2. The said system has distinct advantages of having solid fuel feeding system comprising of variable RPM multi-pocket rotary feeder, screw feeder and two feed nozzles connected to the feeder assembly having different inclination, one is just above the distributor and another is above the bed in the gasifier to handle coal; biomass; washery rejects; and their blends in any proportion in the actual atmosphere which prevails in the commercial gasifier ensuring combustion of some fraction of the feed to provide enthalpy to drive endothermic gasification of the reaming feed to generate syngas for thermal and various downstream applications. Further, while one nozzle is being used for feeding, the other may be used for bed sampling during the experimental run.
3. Freeboard section of the refractory lined gasifier is of sufficient length to ensure desired residence time of the generated syngas at high temperature to produce tar-free syngas from different feedstock as well as minimum fine elutriation.
4. Refractory lining of the gasifier is designed in such a way that it can withstand the pressure, temperature, minimize the erosion and heat loss as well as the expansion and contraction during heating and cooling cycle.
5. The said system is having advantages of reactant feeding system comprising of steam generator with accumulator, air compressor with gas holder, PSA based oxygen generator, booster and header with the provision of heating of different gaseous streams in the range of 150 - 600 °C as per process requirement before entering into the gasifier depending on the combustibility and gasification characteristics of different carbonaceous feedstock.
6. Present device has advantage to withdraw the ash particles either in the dry form or in agglomerated form in a controlled manner. 7. Present system has removable air plenum section of multiple distributors with varying number and sizes of orifices to adjust reactant velocity and flow during endothermic gasification reactions. Removable air plenum has the advantages of easy cleaning and maintenance of the distributor leading to smooth and trouble free operation. 8. Present device has the Provision of Nitrogen flushing arrangement in the entire system to tackle any kind of emergency situation during operation. Inflow of nitrogen dilutes reactant components in the gasifier to stop sudden temperature shoot up which may cause ash agglomeration and clinker formation inside the gasifier.
9. Present device has wide range of operational flexibility with respect to pressure, temperature, feed rate of fuel and gaseous reactant, residence time, particle size and particle density.
10. The present system has also arrangement for product gas analysis with the help of on-line gas analyzer coupled with the system in exit line or provision for collecting the outgoing gas from the sampling port with the help of any gas sampling arrangement for off-line gas analysis purpose

Claims

We Claim:
1. An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier system (40) comprising of: a cylindrical vessel of two different diameters; a gaseous reactant generation and supply system with the provision of preheating and thorough mixing before entering into the gasifier (19); plurality perforation removable conical distributors (20); an air plenum (21); differential pressure measurement instrument across the distributor and bed; a fuel feeding system with a feed hopper (12) arrangement comprising of a Rotary feeder (16A) and a Screw feeder (16B); plurality of feeding nozzles(17,18); an inclined feed lines with the provision of pneumatic conveying of feed materials; an ash withdrawal system consisting of a rotary extractor (22); a purging system; a rupture disc/safety valve; a cyclone separator (26); a quench column(28); a ventury scrubber(36); a knockout drum (mist eliminator, 37); a settling tank (32); a gas sampling port (39); a flare stack (38) and; a nitrogen generator (7) wherein, nitrogen flushing having control panel and data acquisition section to store and display all the data including process parameters enabling wide range of operational flexibility with respect to pressure, temperature, feedstock, feed rate, gaseous reactant, residence time, particle size and particle density.
2. The gasifier system (40) as claimed in claim 1 , wherein the heat resistant refractory lined two-diameter cylindrical gasifier comprises of bed section, freeboard section and in between transition section with the provision for temperature measurement by thermocouples (25).
3. The gasifier system (40) as claimed in claim 1 , wherein the gaseous reactant generation and supply system comprises of a steam generator (1) with an accumulator (2), an air compressor (6) with a gas holder, a PSA based oxygen generator (4), an oxygen booster (5) and a reactant process header (8) with the provision of heating of different gaseous streams in the range of 150-600 °C; wherein, before entering into the gasifier (19) with the aid of, (i) reactant pre-heater (9) for heating air/oxygen enriched air up to 150 °C, (ii) steam super-heater (3) with the capacity of heating up to 250 °C, (iii) reactant mixture-cum-super-heater-I (10) with maximum heating capacity of 400 °C, and (iv) reactant mixture-cum-super-heater-II (11) with the capacity of heating up to 600 °C depending on the combustibility and gasification characteristics of different carbonaceous feedstock.
4. The gasifier system (40) as claimed in claim 1, wherein the removable air plenum (21) is of multiple conical distributors (20).
5. The gasifier system (40) as claimed in claim 1, wherein the solid fuel feeding system with feed hopper (12) arrangement has variable RPM multi -pocket Rotary feeder (16A) and Screw feeder (16B) fitted with feed lock vessel-I (14) and feed lock vessel- II (15) for sequential pressurization and depressurization/isolation by dome valve and actuated ball valve (13), having two feed nozzles (17,18), connected to the feeder assembly with feed line having different inclination, one is just above the distributor and another is above the bed in the gasifier (19) to handle wide range of carbonaceous feedstock.
6. The gasifier system (40) as claimed in claim 1 , wherein the ash withdrawal system is comprising of ash cooler, variable RPM rotary extractor (22), ash lock vessel-I (23) and ash lock vessel-II (24) for sequential pressurization and depressurization/isolation by dome valve and actuated ball valve (13).
7. The gasifier system (40)as claimed in claim 1, wherein the cyclone separator (26) is fitted with one water jacketed cyclone ash lock (27) and dome valve and actuated ball valve (13) for sequential pressurization and depressurization purpose. The gasifier system (40) as claimed in claim 1, wherein the quench column (28) is a jacketed water quench column comprising of two concentric pipes having spray nozzles at the inner shell, quench seal pot (29), quench water tank (31), quench water circulation pump (30) and multi compartment gravity settling tank (32) for separation of scrubbed suspended solids from quench column water stream. The gasifier system (40) as claimed in claim 1, wherein the ventury scrubber (36) is integrated with a ventury alkaline solution seal pot (35), alkaline solution tank (34) and alkaline solution recirculation pump (33) for removal of acidic components from gas stream followed by knockout drum (mist eliminator, 37) for removal of moisture from the gas before sampling and flaring with the help of LPG supported flare stack (38). The gasifier system (40) as claimed in claim 1, wherein the system has provision for product gas analysis with the help of on-line gas analyzer coupled with the system in exit line through gas sampling port (39) or provision for collecting the outgoing gas from the gas sampling port (39) The gasifier system (40) as claimed in claim 1 , wherein the system has process control and data acquisition system comprising of PLC-SCADA control station for controlling and monitoring of gasifier (19) temperature and pressure. The gasifier system (40)as claimed in claim 1, wherein the system having maximum operating temperature up to 1050 °C, pressure up to 10 kg/cm2, feed rate up to 60 kg/hour with particle size acceptability ranging between 0 - 6 mm and the system is capable to gasify coal (non-coking coal up to 60% ash content); biomass; washery rejects; and their blends in a proportion of 0 - 100% (wt%).
PCT/IN2023/050124 2022-02-07 2023-02-07 An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier Ceased WO2023148784A1 (en)

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CN202380020790.7A CN118660949A (en) 2022-02-07 2023-02-07 Pilot-scale pressurized fluidized bed refractory lined gasifier with oxygen-enriched air injection
US18/836,252 US20250197747A1 (en) 2022-02-07 2023-02-07 An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier
AU2023214885A AU2023214885A1 (en) 2022-02-07 2023-02-07 An oxygen enriched air blown pilot scale pressurized fluidized bed refractory lined gasifier.
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EP2380951A2 (en) * 2010-03-24 2011-10-26 Schwarzwald Bioenergie Technik GmbH Device and method for generating useful energy from bioenergy fuels and other organic materials
IN201811014119A (en) * 2018-04-13 2022-09-26

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2380951A2 (en) * 2010-03-24 2011-10-26 Schwarzwald Bioenergie Technik GmbH Device and method for generating useful energy from bioenergy fuels and other organic materials
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