US20140311031A1 - Method and apparatus for ash cooling - Google Patents

Method and apparatus for ash cooling Download PDF

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Publication number
US20140311031A1
US20140311031A1 US14/210,451 US201414210451A US2014311031A1 US 20140311031 A1 US20140311031 A1 US 20140311031A1 US 201414210451 A US201414210451 A US 201414210451A US 2014311031 A1 US2014311031 A1 US 2014311031A1
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Prior art keywords
ash
gasifier
cooler
temperature
water
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US14/210,451
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John D. Winter
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Synthesis Energy Systems Inc
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Synthesis Energy Systems, Inc.
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Priority to US14/210,451 priority Critical patent/US20140311031A1/en
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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
    • 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
    • C10J3/52—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
    • 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
    • C10K1/024—Dust removal by filtration

Definitions

  • the present invention relates to coal gasification using fluidized bed reactor. More specifically, the present invention relates to a method and apparatus for cooling and handling high temperature and high pressure ash discharged from a fluidized bed gasification reactor. The present invention also relates to a method and apparatus for using waste water from a syngas scrubber in the cooling of hot ash discharged from the gasifier.
  • Gasification of carbon containing or carbonaceous materials is used to produce syngas, a mixture of carbon monoxide, hydrogen, carbon dioxide, and other components.
  • gasifiers including a moving bed gasifier, entrained flow gasifier, and fluidized bed gasifier.
  • Carbonaceous feed materials often contains an appreciable ash content, e.g. above 5 wt %.
  • Non-slagging gasifiers used to convert these feed materials commonly operate at temperatures just below the melting point of the ash, and the ash discharged from the gasifier is at a temperature ranging from 500° C. to 1200° C., and under a high pressure (up to 6 bar). This ash must be cooled to ambient temperature, or at least not more than 300° C. for storage and subsequent handling and disposal.
  • thermal energy of the hot ash is not efficiently used or not used at all, imposing a net energy penalty on the system.
  • the ash is discharged directly into water at low or ambient pressures generating steam that is either not recovered or has very limited utility and value due to its low pressure and contamination; or the thermal energy of the hot ash is somehow transferred into cooling water, or using relatively expensive heat transfer equipment to generate low temperature/low pressure steam which is also of low value.
  • U.S. patent application Ser. No. 13/532,769 provides an apparatus and a method for capturing and recycling small fines for fluidized bed reactors or gasifiers operated at high temperatures and pressures in a reliable and simple manner.
  • the raw syngas still contains a significant amount of solids and must undergo further cleaning processes, for the removal of residual solids and undesired gas phase contaminants, such as sulfur compounds, before it can be used in power generation or the production of chemicals.
  • a wet scrubber or water scrubber is commonly used for this purpose, generating a wastewater stream containing salts, dissolved gases and vapors, and suspended solids.
  • the SES process solids are first removed and recycled to the gasifier using cyclones, then a filter is used to remove further solids, and a wet scrubber is lastly used to remove some gas phase contaminants such as halides and any solids that have passed through the filter due to their small particle size or failure of filter elements.
  • the scrubbing liquid typically water, is continually added to and removed from the scrubber, and is henceforth called “makeup” and “blowdown.”
  • the a method and apparatus in the present invention can solve the technical problems as mentioned above and also raise the overall efficiency of the gasification process.
  • this present invention provides a gasification system comprising a fluidized bed gasifier into which a carbonaceous feed material is fed, and out of which a product gas stream and a flowable ash is discharged, wherein the gasifier is operated at a temperature just under a melting point of the ash, and under a pressure not less than 6 bar gauge, and a high temperature ash cooler which is connected to the gasifier and into which the hot ash under pressure is discharged, wherein the high temperature ash cooler comprises a water-supplying apparatus that provides water for cooling the flowable ash, wherein the flowable ash is cooled to a temperature suitable for the ash to be handled with conventional carbon steel equipment.
  • the water supplying apparatus supplies the cooling water to the high temperature ash cooler to be in direct contact with the flowable ash
  • the system further comprises a controller to control the water supplying apparatus so that the water is vaporized upon direct contact with the ash to generate steam, and the flowability of the ash is maintained, and the flowable ash is cooled to a temperature not lower than the pre-determined threshold temperature.
  • the cooling water is supplied to the high temperature ash cooler and cools the ash via indirect heat transfer.
  • the high temperature ash cooler comprises a cooling jacket, or cooling coils, or a cooling panel through which the cooling water flows and absorbs heat indirectly from the hot ash.
  • a portion of the cooling water is supplied to the high temperature ash cooler in direct contact with the flowable ash
  • the system further comprises a controller to control the water supplying apparatus so that the water is vaporized upon direct contact with the ash to generate steam, and the flowability of the ash is maintained; and a portion of the cooling water is supplied to the high temperature ash cooler where the cooling water cools the ash via indirect heat transfer; and wherein the flowable ash is cooled to a temperature not lower than the pre-determined threshold temperature.
  • the system further comprises a connection between the high temperature ash cooler and the gasifier, wherein steam generated from the water supplied to the high temperature ash cooler and is supplied to the gasifier.
  • the system further comprises a depressurizing device which is connected to the high temperature ash cooler to receive the cooled high pressure ash from the high temperature ash cooler, and which is able to reduce the pressure of the ash to ambient pressure.
  • the depressurizing device comprises a double sealed lock hopper.
  • the system further comprises a second ash cooler device which is connected to the high temperature ash cooler to receive the cooled high pressure ash from the high temperature ash cooler, and which is able to further lower the temperature of the ash to ambient temperature.
  • the system further comprises a second ash cooler device which is connected to the depressurizing device to receive the ash from the high temperature ash cooler, and which is able to further lower the temperature of the ash to ambient temperature.
  • the system further comprises a depressurizing device which is connected to the second ash cooling device to receive the ash from the second ash cooling device, and which is able to reduce the pressure of the ash to ambient pressure.
  • the high temperature ash cooler comprises a fluidized bed or a moving bed wherein the high pressure ash makes direct contact with the water from the water supplying apparatus.
  • the water supply apparatus comprises means to disperse the liquid into the ash such as spray nozzles, atomizing spray nozzles, microporous pipes.
  • this invention further provides a gasification system comprising a fluidized bed gasifier into which a carbonaceous feed material is fed, and out of which a product gas stream and a flowable ash are discharged, wherein the gasifier is operated at a temperature just under a melting point of the ash, and under a pressure not less than 6 bar gauge, and wherein the product gas stream comprises gaseous and particulate pollutants, a wet scrubber for removing the pollutants from the product gas stream and producing a waste water stream, an ash cooler connected with the gasifier to receive hot ash from the gasifier; and a connection to deliver at least a portion of the waste water stream to the ash cooler, wherein the waste water stream is converted into steam.
  • a gasification system comprising a fluidized bed gasifier into which a carbonaceous feed material is fed, and out of which a product gas stream and a flowable ash are discharged, wherein the gasifier is operated at a temperature just under a melting point of the ash, and under a pressure not less
  • the ash cooler comprises a high temperature ash cooler connected directly with the gasifier.
  • the ash cooler further comprises a low temperature ash cooler, and wherein the waste water is delivered to the low temperature ash cooler.
  • the waste water makes direct contact with the ash and steam generated from the contact is delivered to the gasifier.
  • some embodiment provide a method for cooling ash discharged from a fluidized bed gasifier, wherein a fluidized bed gasifier is fed with a carbonaceous feed material, and a product gas stream and a flowable ash is discharged out of the gasifier, wherein the gasifier is operated at a temperature just under a melting point of the ash, and under a pressure not less than 6 bar gauge, the method comprising cooling the flowable ash to a temperature suitable for the ash to be handled with conventional carbon steel equipment in a high temperature ash cooler which is connected to the gasifier and into which the hot ash under pressure is discharged, wherein the high temperature ash cooler comprises a water-supplying apparatus that provides water for cooling the flowable ash.
  • the method further comprises controlling the water supplying apparatus so that the water is vaporized upon direct contact with the ash to generate steam, and the flowability of the ash is maintained, and the flowable ash is cooled to a temperature not lower than the pre-determined threshold temperature.
  • the method further comprises receiving the cooled high pressure ash from the high temperature ash cooler, and reducing the pressure of the ash to ambient pressure with a depressurizing device which is connected to the high temperature ash cooler.
  • the method further comprises receiving the cooled ambient pressure ash from the a depressurizing device, and further lowering the temperature of the ash to ambient temperature with a second ash cooler device which is connected to the depressurizing device.
  • certain embodiments provide a method for cooling ash discharged from a fluidized bed gasifier, wherein a fluidized bed gasifier is fed with a carbonaceous feed material, and a product gas stream and a flowable ash are discharged out of the gasifier, wherein the gasifier is operated at a temperature just under a melting point of the ash, and under a pressure not less than 6 bar gauge, and wherein the product gas stream comprises gaseous and particulate pollutants, the method comprising removing the pollutants from the product gas stream and producing a waste water stream with a wet scrubber, and delivering at least a portion of the waste water stream from the wet scrubber to a ash cooler connected with the gasifier which receives hot ash from the gasifier, wherein the waste water stream is converted into steam.
  • the ash cooler comprises a high temperature ash cooler connected directly with the gasifier.
  • the ash cooler further comprises a low temperature ash cooler, and wherein at least a portion of the waste water is delivered to the low temperature ash cooler.
  • the waste water makes direct contact with the ash and steam generated from the contact is delivered to the gasifier.
  • FIG. 1 schematically shows an exemplary overall arrangement of the syngas production system of the present invention, which comprises a gasifier 1 , a high temperature ash cooler 6 , and a low temperature ash cooler 7 .
  • One or more cyclones 2 are provided for recovery and recycle of entrained solids from the crude syngas, with or without heat recovery in a syngas cooler 3 in which boiler feed water is introduced and out of which process steam is produced, with or without filters 4 to further clean the syngas.
  • a wet scrubber 5 downstream of the gasifier is provided to clean the syngas. Wastewater from the scrubber 5 can be fed to a high temperature ash cooler 6 or a low temperature ash cooler 7 , or both.
  • steam is generated. This steam can be fed back into the gasifier 1 (e.g. shown in the high temperature ash cooler 6 ), or be filtered in filter 8 and outputted for other purposes (e.g. shown in the low temperature ash cooler 7 ).
  • FIG. 2 is a block diagram illustrating the sequential arrangement of steps to cool and depressurize the gasifier ash from gasifier conditions to conditions suitable for safe and inexpensive ash handling, according to one embodiment of the present invention.
  • FIG. 3 illustrates the basic structure of a fluidized bed gasifier according to one embodiment of the present invention.
  • a fluidized bed gasifier as shown in FIG. 3 , comprises a vessel housing a headspace 2 above a fluidized bed 1 of the solid material being gasified and a conical perforated gas distribution grid 7 below the bed through which the gasifying medium is introduced at sufficient velocity to fluidize the solid feed material in the gasifier.
  • the gasifying medium steam and/or oxygen
  • the gasifying medium is introduced into the gasifier from the plenum space 4 through the grid 7 to fluidize and partially oxidize the solid feed stock.
  • a passage such as a pipe 6 (“center jet pipe”) in the center region at the bottom of the grid cone introduces oxidant with diluting gas to the bed.
  • Gas velocity of the centre jet pipe 6 is normally greater than the average superficial velocity of gas in the fluidized bed 1 .
  • An ash discharge device 5 comprising an annular passage is provided around this center jet pipe 6 for coal ash agglomerated withdrawal and also for provision of additional gas, such as steam, which may serve to cool and protect the center jet pipe 6 .
  • the ash discharge device 5 is often configured to comprise a venture 3 device for sorting the ash particles at the upside of the passage.
  • a classifier 8 can be intergraded with the ash discharge device 5 .
  • a gas stream, such as steam, moving upwards through the classifier is often used to separate the ash particles, re-entraining those lighter and/or smaller particles whose carbon content is not yet depleted and returning them back into the reaction region,
  • the present invention provides methods and related systems whereby the ash cooling process is separated into respective steps and the first step is a first cooling step under high pressure at high temperature.
  • the first cooling step under high pressure may be by indirect heat transfer of ash with using indirect cooling medium or by direct contacting using direct evaporative cooling liquid.
  • the high temperature ash cooler also referred as “high pressure ash cooler”
  • the temperature of the ash is low enough for the use of conventional equipment. Therefore, further steps such as a depressurization step can be handled at low or medium temperature with equipments of lower cost, thus the investment of equipments is reduced and the reliability of all of the remaining ash handling equipment is also increased.
  • the cooled and depressurized ash can then be cooled further in a low temperate ash cooler 7 and handled using conventional methods.
  • the stepwise system of the present invention recovers heat from said ash in such a manner as to raise the overall efficiency of the gasification process.
  • a feature of the present inventive process is to first cool the ash exiting the gasifier in a high temperature cooler 6 at the gasifier pressure.
  • the temperature of the ash after this high pressure ash cooling step may be determined based on two criteria. First the temperature is high enough such that any steam generated from the high temperature ash cooling has sufficient pressure and can be used to replace part of the fluidizing and reacting steam needed for the gasifier. Second, the temperature of the ash is low enough to allow use of conventional carbon steel equipment, such as vessels, valves, pipes, and conveyors, for the subsequent ash handling. This lowers the cost and increases the reliability of all of the remaining ash handling equipments, particularly the equipment used to remove the ash from a high pressure environment to ambient pressure.
  • the gasification process requires a large amount of steam referred as process steam which is either be generated independently or by cooling the syngas produced in the gasifier such as in a syngas cooler 3 , as shown in FIG. 1 , in the prior art, which is imposing a net energy penalty on the system.
  • process steam which is either be generated independently or by cooling the syngas produced in the gasifier such as in a syngas cooler 3 , as shown in FIG. 1 , in the prior art, which is imposing a net energy penalty on the system.
  • the steam generated in the high temperature ash cooler can be used as port of the process steam, thereby allowing more steam to be exported from the gasification process, or reducing the need of independent steam generation. Thus, at least part of the energy penalty on the gasifier system is released.
  • the lower-temperature ash is then depressurized using lower cost higher reliability equipment, such as carbon steel lock hoppers.
  • a low temperature ash cooling system follows, as shown as a low temperature ash cooler 7 in FIG. 2 , which further cools the ash for ordinary solids handling and disposal.
  • the stepwise process of the present invention lowers capital cost, improves reliability, and improves the overall efficiency of the gasification process.
  • the system for gasifying a carbonaceous material comprises: 1) a gasifier into which the carbonaceous material and gas feeds are fed and gasified to produce a crude syngas product leaving the gasifier from the top and also produce high temperature ash under the operating pressure of the gasifier discharged from the bottom of the gasifier, 2) an ash cooler, as such the high temperature ash cooler, connected with the gasifier, wherein the ash cooler comprises i) a vessel to contain the ash during cooling and ii) an apparatus to cool the ash either via indirect heat transfer or direct contact cooling, and iii) a connection to deliver the steam(“vapor”) generated in step ii) back into the gasifier.
  • the step-wise process of the present invention for cooling the high temperature and high pressure ash discharged from the gasifier comprises a first step wherein the free-flowing ash from the gasifier at the operating temperature of the gasifier is discharged, e.g. by gravity in the case of a fluidized bed gasifier, into a compartment or vessel, in which the ash is cooled.
  • the operating temperature of the gasifier is usually a temperature just below the melting point of the ash e.g. 1200° C.
  • the high-temperature ash cooling compartment itself may be configured as a fluid bed or as a moving bed.
  • the high temperature ash cooler may be a “direct contact” cooler wherein water or other direct evaporative cooling liquid is directly contacted with the hot ash and converted to steam, which flows countercurrent to the ash discharge into the gasifier via a channel connecting the gasifier to the high temperature ash cooler. In this way, the heat energy contained in the ash is used to generate steam which is used directly in the gasification reactor.
  • Direct contact may be affected by many methods well-known to those skilled in the art.
  • water preferably atomized
  • This may be done via a water supply apparatus which comprises means to disperse the water into the ash such as spray nozzles, atomizing spray nozzles, microporous pipes, which for example may be made from sintered metal powder or fibers, pipes or other flow channels with drilled holes.
  • This direct contact cooling step can be achieved in either a moving bed or fluid bed ash cooler.
  • Indirect cooling can be used in combination with or instead of direct contact cooling. Whether this is means of jacketing of the vessel, cooling coils, or cooling panels or any other common means of indirect heat transfer, a indirect cooling medium is heated or evaporated in a flow channel separated from the ash. Steam is generated in the flow channel and is relatively clean compared to the steam generated via direct contact. Preferably, the steam is at a pressure higher than that of the gasifier and can be used in the gasifier or for other uses.
  • the ash After the high temperature cooler, the ash reaches a temperature at which any further handling or processing can be accomplished using e.g. ordinary carbon steel materials, which function well and reliably at a temperature below 500° C., preferably below 350° C.
  • the ash may be reduced in pressure, e.g. in a depressurizer, to ambient pressure for any further handling or cooling. This can be achieved by a variety of means, such as via valves and lock-hoppers well-known to those skilled in the art. These are conventional equipment and can operate rather reliably at a temperature of 300-550° C. even under the operating pressure of the gasifier.
  • a lock hopper is a well-known depressurizing device, and generally comprises a vessel into and out of which the ash flows by gravity, with valves at the top and bottom that seal against pressure and solids flow, and means to pressurize and depressurize the vessel, and associated valves and controls to regulate the gas flow.
  • the cooled and depressurized ash may optionally undergo a further cooling step using a second cooler, or a low temperature ash cooler, for ease of handling or safe disposal, e.g. to not more than 140° C. for handling via belt conveyors.
  • a second cooler or a low temperature ash cooler
  • a scrubber blowdown (described below in detail) may be used in direct contact with the ash to provide cooling, transfer salts and suspended solids to the ash, and further recover water without salt for reuse, thus lowering wastewater treatment and reducing overall water consumption.
  • a two-step cooling process i.e. a high pressure cooling followed by depressurizing
  • a two-step cooling process thus allows the overall cost of an ash cooling and depressurization system to be lowered, its reliability increased, and the bulk of the heat available in the ash, which is the heat of the ash from gasifier operating temperature to the exit temperature of the high temperature ash cooler, is directly converted to process steam.
  • the process steam converted has the highest value possible for a gasifier system, for use in the gasifier without any addition steam handling.
  • the high temperature cooler may also be designed to cool the ash to a lower temperature such that a low temperature ash cooler is not needed.
  • a process may be desired if high process efficiency is needed, especially when the gasifier feed has high ash content.
  • Such a lower temperature may be achievable even with direct contact cooling, so long as the water saturation pressure at the exit temperature of the high temperature ash cooler is above the gasifier operating pressure.
  • the high temperature cooler may also be designed to cool the ash to a lower temperature and the cooled ash is cooled by a low temperature ash cooler.
  • the depressurizer is not needed. Such a process may be desired when the pressure of the cooled ash is needed.
  • hot ash passes from the gasifier 1 into the ash cooling apparatus.
  • the hot ash may be at a temperature from 500° to 1200° C. at the discharge point from the gasifier 1 .
  • the temperature of the ash leaving the ash cooling device is determined by the operating pressure of the gasifier. As long as the saturation pressure of water at the ash exit temperature is above the gasifier operating pressure, water can be injected directly into the moving or fluid ash.
  • the “pre-determined threshold temperature” may be determined by the following two factors. Firstly, in order to keep the flowability of the ash, liquid water should be avoided in the ash cooler. Thus, the temperature of the cooled ash (T 1 ) should be kept at least above the boiling point of water at the ash cooling pressure. Preferably, the temperature is at or above the critical temperature of water (i.e. 374° C.). Secondly, since the steam generated flows into the gasifier (more detail below), the pressure of the steam should be above the pressure of the points at which the steam is introduced into the gasifier. Thus, the temperature of the cooled ash (T 2 ) should be high enough. Therefore, the pre-determined threshold temperature should not be lower than either T 1 or T 2 .
  • the rate and amount of water is controlled so that it is dispersed and mixes with the hot solids properly, and completely evaporates without affecting the flowability of the ash.
  • the steam thus generated moves up into the reacting zone of gasifier.
  • the flow of the cooling water can controlled by a flow control device such as a control valve where the flow of the water is controlled by temperature or pressure measurement in the ash cooler to regulate to the amount of cooling desired.
  • a flow control device such as a control valve where the flow of the water is controlled by temperature or pressure measurement in the ash cooler to regulate to the amount of cooling desired.
  • the thermal energy contained in the hot ash is used to generate steam needed for the gasification reaction, thus displacing the amount of clean, high pressure steam otherwise needed in the gasification reaction and typically generated in a separate boiler.
  • the steam generated by direct contact with the ash is a “dirty” steam containing a variety of contaminants, making it unsuitable for most other purposes, but suitable for use in the gasification process.
  • the steam generated by direct or indirect contact can be introduced in the gasifier through various points of the gasifier. As shown in FIG. 3 , the steam can flow into the plenum space 4 via a channel and then be introduced in the gasifier through the grid 7 , or be introduced into the center jet pipe 6 as part of the jet gas, or through the classifier 8 integrated with the ash discharge device 5 . Since steam generated by direct contact contains ash which may cause grid plug problem for the grid 7 , this direct contacting steam, preferably, is introduced to the classifier 8 , such as through the classifier gas inlet on the classifier 8 .
  • the ash is first cooled to reach a temperature typically in the region of 300 to 550° C. in a vessel of the high temperature ash cooler 6 at a pressure close to the gasifier pressure.
  • the ash is then depressurized to ambient pressure via equipment such as lock-hoppers.
  • equipment such as lock-hoppers.
  • some form of isolation valve may be required between the high pressure region and the low pressure region and this valve is far less expensive and more reliable at the exit temperature of the high temperature ash cooler than a valve specified for service at temperatures (800 to 900° C.) near the gasifier temperature (typically 1000° C. for the SES gasifier).
  • a valve specified for service at temperatures (800 to 900° C.) near the gasifier temperature (typically 1000° C. for the SES gasifier).
  • the invention further provides a method and system of coal gasification wherein at least a part of wastewater stream generated from one or more of the gas cleaning steps (e.g. the scrubber blowdown water) is recycled and applied to the hot ash residue from the gasification process, in such a manner that the salts and suspended solids in the waste water remain with the ash, wherein steam is generated in the process, which steam may be used for several purposes such as being fed back to the gasification process.
  • the amount of water sent to wastewater treatment of the system is reduced.
  • the invention provides a system for gasifying a carbonaceous material, referring to FIG. 1 , wherein the system comprises:
  • At least one device to remove a portion of the particulate pollutants and recycle the solids in the crude syngas such as cyclone 2 , cool the crude syngas such as syngas cooler 3 ;
  • At least one ash cooler connected with the gasifier to receive hot ash under pressure from the gasifier, such as the high temperature ash cooler 6 ;
  • the waste water stream from the scrubber can be delivered to either or both of the high temperature ash cooler or low temperature ash cooler. Because the ash temperature is much higher than the boiling point of water in either of the ash coolers, the water in the waste water stream, along with other volatile components will evaporate, to generate a supply of steam, while leaving the particulate pollutants and other non-volatile components behind with the ash particles.
  • the supply of steam from the high temperature ash cooler is directed to the gasifier and supplements the steam supply needed for the gasification process. Steam generated from the wastewater used in the low temperature ash cooler may be condensed in use as a low temperature heat source or the condensate used as process water makeup.
  • this invention deals with the recycle of waste water emanating from a water scrubber used for removing solids from product syngas from e.g. a fluidized bed coal gasification process.
  • a water scrubber follows the cyclones and filters (e.g. bag house filters or candle filters) used to remove solids from the gas. This scrubber captures most, or nearly all, of the halide, ammonia, cyanides, remaining particulate matter not removed in the cyclones and filters, and some trace gas species that are at least partially water soluble.
  • Scrubbers or wet scrubbers suitable for the present invention, are common and well-known devices that use liquid to wash and remove unwanted particulate and/or gas pollutants from a gas stream. There are a diverse group of such devices that can be used. Scrubbers are one of the primary devices that control gaseous emissions, especially acid gases. Scrubbers can also be used for heat recovery from hot gases by flue-gas condensation. Wet scrubbing works via the contact of target compounds or particulate matter with the scrubbing solution, which may simply be water. Water soluble toxic and/or corrosive gases like HCl, H 2 S, SO 2 or ammonia (NH 3 ) can be removed very well by a wet scrubber. The water spray may also condense certain condensables such as tar and oil. Removal efficiency of pollutants is improved by increasing residence time in the scrubber or by the increase of surface area of the scrubber solution by e.g. spraying.
  • a portion (which includes all or none) of the waste water stream from the scrubber which contains the removed contaminants may be applied directly to contact with hot gasifier ash at the gasifier operating pressure which is typically, but not restricted to, 10 to 60 bar.
  • the waste water stream may be applied in indirect heat transfer against the hot ash, and substantially evaporated.
  • the steam generated from the cooling or the hot ash and any contaminants in the wastewater stream that evaporate with the steam can be re-introduced into the gasifier as part of the required steam for gasification purposes, reducing the overall water requirements for the gasification plant.
  • a portion or all of the wastewater stream can be applied to the ash directly in a low pressure ash cooling step.
  • some of the water may be used to partially hydrate the ash for dust control in handling, for example raising the hot ash water content from essentially zero to 5 wt %.
  • Some of the water evaporates and this steam may also be as a low temperature heat source with the condensate reused as process water, be vented, be sent to a flare, or condensed and reused as process water after removal of any entrained ash.
  • the method of the present invention places the salts and suspended solids from the wastewater into the ash product from the gasifier, reduces plant water consumption, and wholly or in part eliminates wastewater treatment for the gasification process.
  • the high pressure steam generated from the direct injection of waste water to the hot ash can be directly connected to the gasifier, without having been cleaned to remove any entrained ash particles, thereby reducing the need for high pressure clean steam, and resulting in significant increase in heat energy efficiency, yet only minimal increase in capital costs.

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  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Processing Of Solid Wastes (AREA)
US14/210,451 2013-03-15 2014-03-14 Method and apparatus for ash cooling Abandoned US20140311031A1 (en)

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US20140260973A1 (en) * 2013-03-14 2014-09-18 John Winter Method and apparatus for recycling ash fines
US9823021B2 (en) * 2012-05-24 2017-11-21 Kellogg Brown + Root LLC Methods and systems for cooling hot particulates
US10329506B2 (en) * 2017-04-10 2019-06-25 Thermochem Recovery International, Inc. Gas-solids separation system having a partitioned solids transfer conduit

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US11143163B2 (en) 2016-03-08 2021-10-12 Semtive Inc. Vertical axis wind turbine
US11664663B2 (en) 2018-09-12 2023-05-30 Semtive Inc. Micro inverter and controller

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US9823021B2 (en) * 2012-05-24 2017-11-21 Kellogg Brown + Root LLC Methods and systems for cooling hot particulates
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US10329506B2 (en) * 2017-04-10 2019-06-25 Thermochem Recovery International, Inc. Gas-solids separation system having a partitioned solids transfer conduit

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AU2014240146B2 (en) 2018-09-20
WO2014152073A3 (en) 2014-11-13
WO2014152073A2 (en) 2014-09-25
AU2014240146A1 (en) 2015-09-10
CN105247018A (zh) 2016-01-13

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