CN114250086B - Slag cooling method and device - Google Patents
Slag cooling method and device Download PDFInfo
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- CN114250086B CN114250086B CN202111570017.7A CN202111570017A CN114250086B CN 114250086 B CN114250086 B CN 114250086B CN 202111570017 A CN202111570017 A CN 202111570017A CN 114250086 B CN114250086 B CN 114250086B
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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
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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
- C10J3/46—Gasification of granular or pulverulent flues in suspension
- C10J3/48—Apparatus; Plants
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
- Y02E20/18—Integrated gasification combined cycle [IGCC], e.g. combined with carbon capture and storage [CCS]
Abstract
The invention discloses a slag cooling method and a slag cooling device. The slag cooling method comprises the following steps: discharging slag in a first temperature range into a main cold slag pot; introducing main cooling gas into the main slag cooling tank, wherein the main cooling gas is divided into upward flowing divided cooling gas and downward flowing divided sealing gas in the main slag cooling tank; cooling slag in a first temperature range by diverting cooling gas to obtain slag in a second temperature range; and discharging the slag and the shunt sealing gas in the second temperature range along a main cold slag pot outlet of the main cold slag pot, wherein the shunt sealing gas downwards flows through the main cold slag pot outlet to play a role in gas sealing on the main cold slag pot outlet.
Description
Technical Field
The invention relates to the technical field of fuel gasification, in particular to a slag cooling method and a slag cooling device.
Background
In the fluidized bed gasification technology, the cooling of high-temperature bottom slag is a necessary operation, and the efficient cooling of high-temperature bottom slag and the coordination and matching of the high-temperature bottom slag and the gasification furnace are important preconditions for smooth and safe slag discharge and are key factors for ensuring the long-term stable operation of the gasification furnace.
In the process of realizing the invention, the heat exchange efficiency of the traditional slag cooling system is lower, the slag discharging port does not have a pressure sealing function, and gasifying agent/coal gas reverse channeling and cooling gas leakage are easy to occur.
Disclosure of Invention
In view of the above, the present invention provides a slag cooling method and apparatus to at least partially solve the problems in the prior art.
One aspect of the present invention provides a slag cooling method, comprising:
discharging slag in a first temperature range into a main cold slag pot;
introducing main cooling gas into the main slag cooling tank, wherein the main cooling gas is divided into upward flowing divided cooling gas and downward flowing divided sealing gas in the main slag cooling tank;
cooling slag in a first temperature range by diverting cooling gas to obtain slag in a second temperature range;
and discharging the slag and the shunt sealing gas in the second temperature range along a main cold slag pot outlet of the main cold slag pot, wherein the shunt sealing gas downwards flows through the main cold slag pot outlet to play a role in gas sealing on the main cold slag pot outlet.
According to an embodiment of the invention, wherein:
after the slag in the first temperature range is discharged into the main slag cooling tank, the slag is uniformly distributed downwards along the main slag cooling tank;
and after the upward flowing split cooling gas is in countercurrent contact with the slag in the first temperature range, cooling the slag in the first temperature range.
According to an embodiment of the invention, wherein the main cooling gas comprises a carbon dioxide cooling gas;
Wherein, cooling slag in a first temperature range by diverting cooling gas includes:
the slag in the first temperature range is chemically cooled by utilizing chemical endothermic reaction between the split cooling gas and carbon residues in the slag in the first temperature range while the split cooling gas is used for physically cooling the slag in the first temperature range.
According to an embodiment of the present invention, the method further includes:
discharging the slag in the second temperature range through the outlet of the main slag cooling tank, and then introducing the slag into the safety slag cooling tank;
and cooling the slag in the second temperature range through the security cooling slag tank to obtain the slag in the third temperature range.
According to an embodiment of the invention, wherein cooling the slag in the second temperature range by the An Baoleng slag pot comprises:
introducing security cooling gas into the security cooling slag tank so as to cool slag in a second temperature range through the security cooling gas; and/or
In the security cold slag pot, the slag in the second temperature range is cooled by adopting a circulating water indirect cooling mode.
According to an embodiment of the invention, wherein:
the security cooling gas comprises carbon dioxide cooling gas;
The slag in the second temperature range has a temperature lower than T 5％ Wherein T is 5％ The chemical reaction temperature is corresponding to the reduction rate of carbon dioxide of 5% in the process of the reduction reaction of carbon and carbon dioxide under the preset reaction conditions.
According to an embodiment of the invention, wherein the primary cooling gas is introduced into a first region of the primary slag ladle;
the slag cooling method further comprises the following steps:
introducing auxiliary cooling gas into the main slag cooling tank, wherein the auxiliary cooling gas is introduced into a second region of the main slag cooling tank;
wherein the second region is located higher than the first region, and the temperature in the second region is higher than the temperature in the first region, and the auxiliary cooling gas adopts one of the following: steam, carbon dioxide, a mixture of carbon dioxide and steam.
According to an embodiment of the invention, wherein:
the slag in the first temperature range comes from a hearth of the gasifier, wherein in the hearth of the gasifier, the fuel and the gasifying agent generate slag and raw gas in the first temperature range after gasification reaction;
the slag cooling method further comprises the following steps:
the crude gas is subjected to gas-solid separation, cooling and dust removal to obtain clean gas;
the clean coal gas is converted by water gas to obtain a mixed gas of carbon dioxide and hydrogen;
Separating the mixed gas of carbon dioxide and hydrogen to obtain carbon dioxide product gas;
and introducing the carbon dioxide product gas serving as main cooling gas into a main slag cooling tank.
According to an embodiment of the invention, wherein:
the main slag cooling tank comprises a first main slag cooling tank and a second main slag cooling tank, wherein the first main slag cooling tank and the second main slag cooling tank run simultaneously; or alternatively
One of the first main slag cooling tank and the second main slag cooling tank is used as a standby slag cooling tank.
Another aspect of the present invention provides a slag cooling apparatus for implementing the above slag cooling method, comprising:
a primary cold slag pot, wherein the primary cold slag pot comprises:
a main cold slag pot inlet for discharging slag within a first temperature range into the main cold slag pot;
a main cooling gas injection port for introducing main cooling gas into the main slag cooling tank, wherein the main cooling gas is divided into a divided cooling gas flowing upwards and a divided sealing gas flowing downwards in the main slag cooling tank; the slag in the first temperature range is cooled by the split cooling gas, and then the slag in the second temperature range is obtained;
and the main cold slag pot outlet is used for discharging slag and split-flow sealing gas in the second temperature range, wherein the split-flow sealing gas downwards flows through the main cold slag pot outlet to play a role in air sealing on the main cold slag pot outlet.
According to an embodiment of the present invention, the above apparatus further includes:
and the security cold slag pot is used for cooling slag in the second temperature range to obtain slag in the third temperature range.
According to an embodiment of the invention, wherein:
an Baoleng slag pot is provided with circulating water cooling device for adopt circulating water indirect cooling's mode to cool down the slag in the second temperature range.
According to the embodiment of the invention, the security cold slag pot is further provided with:
the safety cold slag tank inlet is communicated with the main cold slag tank outlet and is used for introducing the safety cold slag tank after the slag in the second temperature range is discharged through the main cold slag tank outlet;
the safety gas injection port is used for introducing safety cooling gas into the safety cold slag tank so as to cool slag in a second temperature range through the safety cooling gas;
and the safety cold slag pot outlet is used for discharging slag in a third temperature range.
According to an embodiment of the invention, wherein:
the slag in the first temperature range comes from a hearth of the gasifier, wherein in the hearth of the gasifier, the fuel and the gasifying agent generate slag and raw gas in the first temperature range after gasification reaction;
The slag cooling device further comprises:
the crude gas treatment system is used for obtaining clean gas after gas-solid separation, cooling and dust removal of the crude gas;
the water gas conversion device is used for converting the clean gas into a mixed gas of carbon dioxide and hydrogen after the water gas conversion;
and the gas separation device is used for separating the mixed gas of the carbon dioxide and the hydrogen gas to obtain carbon dioxide product gas, wherein an outlet of the gas separation device is communicated with the main cooling gas injection inlet, and the carbon dioxide product gas is used as main cooling gas and is introduced into the main slag cooling tank.
According to an embodiment of the invention, the primary cold slag pot comprises a first primary cold slag pot and a second primary cold slag pot, wherein the first primary cold slag pot and the second primary cold slag pot are operated simultaneously; or alternatively
One of the first main slag cooling tank and the second main slag cooling tank is used as a standby slag cooling tank.
According to an embodiment of the invention, wherein:
the main cooling air injection port is arranged obliquely downwards, and the included angle between the central axis of the main cooling air injection port and the horizontal plane is 5-60 degrees.
According to the embodiment of the invention, the high-temperature slag in the main slag cooling tank is cooled by introducing the cooling gas, and the gas sealing effect is achieved on the outlet of the slag cooling tank by utilizing part of the cooling gas while the high-temperature slag is cooled, so that leakage or reverse channeling of gasifying agent, coal gas and cooling gas can be avoided, and the safety problem caused by leakage of combustible gas is prevented. Part of the cooling gas forms upward air flow, and the gasification agent/gas is further prevented from reversely channeling into a slag cooling system while cooling slag, so that the phenomenon of slag bonding caused by the reaction of the gasification agent/gas and high-temperature bottom slag is reduced.
Drawings
Fig. 1 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to an embodiment of the present invention.
Fig. 2 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
Fig. 3 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
Fig. 4 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
Fig. 5 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
Reference numerals illustrate:
10-hearth; 11-a gas-solid separator; 12-a material returning device; 13-a gas cooler; 14-a dust remover; 15-a water gas shift unit; 16-a gas separation device; 20-a main slag cooling tank; 21-a main slag cooling tank inlet; 22-a main slag cooling tank outlet; 23-main cooling gas injection port; 24-auxiliary cooling gas injection port; 25-valve; 30-security cold slag pot; 31-safety cold slag pot outlet; 32-a security gas injection port.
A-gasifying agent; b-fuel; c-primary cooling gas; c1-security cooling gas; d-fly ash; e-low-temperature bottom slag; f-cleaning coal gas; h-hydrogen; i-carbon dioxide product gas; j-excess carbon dioxide; s-auxiliary cooling gas; w is circulating water.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expressions should generally be interpreted in accordance with the meaning as commonly understood by those skilled in the art (e.g.," a system having at least one of A, B and C "shall include, but not be limited to, a system having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.). Where a formulation similar to at least one of "A, B or C, etc." is used, in general such a formulation should be interpreted in accordance with the ordinary understanding of one skilled in the art (e.g. "a system with at least one of A, B or C" would include but not be limited to systems with a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
In the fluidized bed gasification technology, pulverized coal with the diameter of 0-10 mm is generally adopted as a raw material, the gasification temperature is mild, and part of coarse particle coal cannot be fully converted to form high-temperature bottom slag. In the fluidized bed gasification process, in order to ensure continuous and safe production, the high Wen Dezha is required to be discharged out of the system after being cooled.
In the process of realizing the disclosure, the grain size distribution range of the bottom slag is relatively narrow compared with that of the raw coal entering the furnace, and the bottom slag is mainly large grains, few fine grains and very few or even no superfine grains are found. The particle size distribution characteristics enable the void ratio of the bottom slag layer to be high, the bottom slag layer cannot play a role of a material seal, and gasifying agent/coal gas reverse channeling and cooling gas leakage are easy to occur. Gasifying agent/coal gas reversely flows into a slag cooling system, is easy to react with high-temperature bottom slag to cause slag bonding, and has potential safety hazard. If the cooling gas contains combustible gas, the cooling gas is leaked to easily cause safety problems such as combustible gas flash explosion. Therefore, the efficient cooling of the high-temperature bottom slag and the coordination and matching with the gasifier are important preconditions of smooth and safe slag discharge, and are also key factors for ensuring the long-term stable operation of the gasifier.
The traditional fluidized bed gasification process generally adopts a roller slag cooler to cool high-temperature bottom slag, but has the following problems: on one hand, the roller slag cooler adopts circulating water to indirectly exchange heat for high-temperature bottom slag, so that the heat exchange efficiency is low, and the heat cannot be recycled; on the other hand, the roller slag cooler does not have a pressure sealing function, so that gasification agent/gas reverse channeling is easy to occur, and potential safety operation hazards exist.
In view of the above, the present invention provides a slag cooling method to solve the above technical problems.
The slag cooling method comprises the following steps:
discharging slag in a first temperature range into a main cold slag pot;
introducing main cooling gas into the main slag cooling tank, wherein the main cooling gas is divided into upward flowing divided cooling gas and downward flowing divided sealing gas in the main slag cooling tank;
cooling slag in a first temperature range by diverting cooling gas to obtain slag in a second temperature range;
and discharging the slag and the shunt sealing gas in the second temperature range along a main cold slag pot outlet of the main cold slag pot, wherein the shunt sealing gas downwards flows through the main cold slag pot outlet to play a role in gas sealing on the main cold slag pot outlet.
Fig. 1 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to an embodiment of the present invention. The slag cooling method according to the embodiment of the present invention will be described with reference to fig. 1, and as shown in fig. 1, the method includes:
The slag in the first temperature range is discharged into the main cold slag tank 20, wherein the slag in the first temperature range is high-temperature slag from the hearth 10, the gasifying agent A and the fuel B generate high-temperature slag of 900-1100 ℃ after gasification reaction in the hearth 10, the upper part of the main cold slag tank 20 is provided with the main cold slag tank inlet 21 which is communicated with a slag discharging port of the hearth 10, and the high-temperature slag enters the main cold slag tank 20 from the main cold slag tank inlet 21 and moves downwards in the main cold slag tank 20 in a moving bed mode.
According to the embodiment of the invention, the particle diameter of high-temperature bottom slag generated by the gasification furnace is less than 10mm, and the particle diameter is less than 0.2mm and less than 10%. The high temperature bottom slag contains carbon and ash as main components, and contains small amount of hydrogen, water and volatile matters. The carbon content of the bottom slag is related to the components, reaction characteristics, gasification furnace reaction conditions and the like of the fuel B, and the carbon content is generally between 15% and 80%.
In accordance with an embodiment of the present invention, the method of cooling the high temperature slag in the primary slag pot 20 is by cooling with a cooling gas, specifically, the primary cooling gas C is introduced into the primary slag pot, wherein the primary cooling gas C is divided into an upward flow of the divided cooling gas and a downward flow of the divided sealing gas in the primary slag pot. The high-temperature slag in the first temperature range is cooled by the split cooling gas to obtain low-temperature slag in the second temperature range, and the cooled slag is discharged out of the system from a main slag cooling tank outlet 22 at the bottom of the main slag cooling tank 20. The low-temperature slag in the second temperature range can be obtained by directly cooling the high-temperature slag to the slag discharge temperature through a main slag cooling tank, namely, about 100 ℃, or cooling the high-temperature slag to an intermediate temperature (such as about 400 ℃) through the main slag cooling tank for discharge, and then further cooling the high-temperature slag to the slag discharge temperature through a next stage slag cooling tank or other cooling modes.
According to the embodiment of the present invention, the main cooling gas C may be a mixed gas of one or more of water vapor, carbon dioxide, nitrogen, etc., and preferably carbon dioxide may be used.
In addition, the cooled low-temperature slag and the split-flow sealing gas are discharged along the outlet of the main cold slag tank, and the split-flow sealing gas downwards flows through the outlet of the main cold slag tank to play a role in gas sealing on the outlet of the main cold slag tank.
According to the embodiment of the invention, the reaction temperature of the fluidized bed gasifier is between 900 ℃ and 1100 ℃, and particularly, in the operation process of the gasifier, the highest temperature at the bottom of the hearth 10 is controlled to be 50-150 ℃ lower than the softening temperature of fuel ash in a weak reducing atmosphere state, so that the bottom of the hearth is prevented from exceeding Wen Jiezha. Wherein, the fuel ash refers to the residue left after the fuel is completely combusted and gasified.
According to the embodiment of the invention, the fuel B is all solid fuels which can be utilized by the fluidized bed gasification furnace, including but not limited to one or more solid fuels such as coal, biomass, semicoke, municipal refuse, petroleum coke and the like, and the particle size of the fuel is preferably less than 10mm, so that the fuel preparation process is simple and the investment and operation cost is low.
According to embodiments of the present invention, gasifying agent A may be a mixture of one or more of pure oxygen, oxygen-enriched air, water vapor, or carbon dioxide. The gas components and the heat value can be adjusted by adjusting the gas quantity, the oxygen concentration, the steam quantity, the fuel quantity and the like of the gasifying agent so as to meet the gas requirements of different downstream users.
According to the embodiment of the invention, in the gasification reaction process, the bottom pressure of the hearth 20 is about 8-20kpa, the pressure of the main slag cooling tank 20 is interlocked with the bottom pressure of the hearth 20, and the pressure of the main slag cooling tank 20 is kept to be 0.5-5kpa higher than the bottom of the hearth, so that the back channeling of coal gas and gasifying agent can be prevented.
According to the embodiment of the invention, the high-temperature slag in the main slag cooling tank is cooled by introducing the cooling gas, and the gas sealing effect is achieved on the outlet of the slag cooling tank by utilizing part of the cooling gas while the high-temperature slag is cooled, so that leakage or reverse channeling of gasifying agent, coal gas and cooling gas can be avoided, and the safety problem caused by leakage of combustible gas is prevented. Part of the cooling gas forms upward air flow, and the gasification agent/gas is further prevented from reversely channeling into a slag cooling system while cooling slag, so that the phenomenon of slag bonding caused by the reaction of the gasification agent/gas and high-temperature bottom slag is reduced.
According to an embodiment of the present invention, as shown in fig. 1, a main cooling gas injection port 23 is provided in the main slag pot for introducing the main cooling gas C. Wherein: after the slag in the first temperature range is discharged into the main slag cooling tank 20, the slag is uniformly distributed downwards along the main slag cooling tank 20; the main cooling gas C is introduced along the main cooling gas injection port 23 of the main slag-cooling tank 20, and after the partial cooling gas in the main cooling gas C, that is, the split cooling gas flowing upward, is in countercurrent contact with the slag in the first temperature range, the slag in the first temperature range is cooled.
According to the embodiment of the invention, in the process that the split cooling gas flows upwards along the slag falling channel, the split cooling gas is fully contacted with the high-temperature slag in a countercurrent manner, so that the heat exchange cooling effect is enhanced, and the heat exchange efficiency is improved.
According to an embodiment of the present invention, wherein the main cooling gas may be carbon dioxide cooling gas.
When the main cooling gas adopts carbon dioxide as the cooling gas, cooling the slag in the first temperature range by the split cooling gas includes:
the slag in the first temperature range is subjected to countercurrent contact heat exchange through the split cooling gas (carbon dioxide), and is subjected to chemical cooling by utilizing chemical endothermic reaction (carbon monoxide generation) between the split cooling gas (carbon dioxide) and residual carbon in the slag in the first temperature range while the physical cooling is carried out. The other part of carbon dioxide (split flow sealing gas) flows downwards along with the cooled bottom slag, plays a role in gas seal on the outlet of the main slag cooling tank, can effectively inhibit carbon monoxide generated by the reaction of the high-temperature bottom slag and the carbon dioxide from flowing downwards, and avoids potential safety hazards caused by gas reverse channeling. Simultaneously, the generated carbon monoxide and residual carbon dioxide circulate upwards, enter the hearth of the gasification furnace through the inlet of the main cold slag pot at the top of the main cold slag pot, and the carbon dioxide continuously participates in the gasification reaction.
According to the embodiment of the invention, although the main cooling gas can be one or a combination of a plurality of gases such as nitrogen, water vapor and carbon dioxide, from the point of resource utilization, the carbon dioxide or the water vapor is superior to the nitrogen as the cooling gas, because the carbon dioxide or the water vapor can react with carbon in high-temperature bottom slag to generate active ingredients in the coal gas, and the residual carbon dioxide or the water vapor can also enter the gasification furnace to continuously participate in gasification reaction. However, because the physical properties and the reaction characteristics of the carbon dioxide and the water vapor are obviously different, the operation of the slag cooling device and the slag cooling effect are affected, and the carbon dioxide has more obvious advantages than the water vapor in comprehensive consideration. See for details the following description:
the reaction of carbon with carbon dioxide is shown in formula (one):
The reaction of carbon with water vapor is shown in formula (two):
As can be seen from the formula (a) and the formula (b), the heat absorbed by the reaction of one mole of carbon and carbon dioxide is 1.3 times of the heat absorbed by the reaction of the carbon dioxide and water vapor, and from the aspect of chemical cooling, carbon dioxide is used as cooling gas, so that the heat absorbed by the chemical reaction is larger, and the temperature of high-temperature bottom slag can be obviously reduced by the chemical reaction. Furthermore, the specific heat of the carbon dioxide is higher than that of the water vapor, the capacity of carrying heat is strong, and the cooling effect is due to the water vapor from the viewpoint of physical cooling; when the same bottom slag is cooled, the equipment is small in volume, the high specific heat characteristic of the dioxide can be fully utilized, and the slag cooling efficiency is improved.
In addition, carbon dioxide is used as cooling gas, and the cooling gas can be converted into carbon monoxide which is an effective gas in the coal gas through chemical reaction between the cooling gas and the carbon, so that the carbon dioxide can be recycled.
In addition, the method of spraying water or introducing water vapor has the following technical defects: on the one hand, a large amount of water resources are consumed; on the other hand, the adoption of steam slag cooling has very strict operation requirements. In the process of contacting with hot slag, if the water vapor quantity is improperly regulated or the partial mixing/fluidization is uneven or the partial temperature is lower, the problems of hardening of bottom slag, unsmooth slag discharging and the like are easily caused by water vapor condensation; the problem of incomplete vaporization or partial recondensing after vaporization easily occurs in water spraying, and the problem of unsmooth slag removal caused by hardening of bottom slag affects the long-period stable operation of the gasifier.
In conclusion, according to the embodiment of the invention, due to stable property of carbon dioxide, the problems of hardening of bottom slag and unsmooth slag discharge caused by water vapor or water spray cooling can be avoided, so that the long-period stable operation of the fluidized bed gasifier can be ensured. Carbon dioxide is used as cooling gas, so that the slag can be cooled physically and chemically at the same time, the cooling speed is high, the high specific heat characteristic of the dioxide and the large heat absorption capacity of the chemical reaction are utilized, and compared with other gases used as cooling gas, the slag cooling efficiency can be improved. Furthermore, carbon dioxide is used as a cooling gas, and the cooling gas can be converted into carbon monoxide which is an effective gas in the gas through a chemical reaction between the cooling gas and the carbon, so that the carbon dioxide can be recycled. Solves the problems of low slag cooling efficiency, easy hardening of bottom slag, unsmooth slag discharge and the like of the traditional fluidized bed gasifier, and realizes the optimal operation of energy recycling and systems.
Fig. 2 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention. As shown in fig. 2, in this embodiment, a two-stage cooling mode is adopted, specifically:
the high-temperature slag in the first temperature range is cooled to slag in the second temperature range through the main slag cooling tank 20, namely, the slag is firstly cooled to an intermediate temperature (such as about 400-700 ℃), then the slag in the second temperature range is discharged through the outlet of the main slag cooling tank and then is led into the next stage of slag cooling tank, namely, the safety slag cooling tank 30, the slag in the second temperature range is cooled through the safety slag cooling tank 30 to obtain slag in the third temperature range, namely, the slag is cooled to the slag discharging temperature of about 100 ℃, and then the low-temperature bottom slag E is discharged.
According to an embodiment of the invention, wherein cooling the slag in the second temperature range by the An Baoleng slag pot comprises:
introducing security cooling gas C1 into the security cooling slag tank so as to cool slag in a second temperature range through the security cooling gas C1; and/or in the security cold slag tank, adopting a circulating water W indirect cooling mode to cool slag in a second temperature range. Preferably, the method of introducing the security cooling gas C1 into the security cold slag tank and adopting the circulating water W to indirectly cool the security cold slag tank can be adopted, so that the slag in the second temperature range is cooled, and the heat exchange effect can be improved.
According to an embodiment of the invention, wherein: the security cooling gas can adopt carbon dioxide cooling gas.
According to an embodiment of the present invention, the benefit of introducing carbon dioxide as security cooling gas to security slag pot 30 is: firstly, the carbon dioxide can continuously exchange heat with bottom slag in the security cold slag pot 30, so that the temperature of the bottom slag is reduced; in addition, the carbon dioxide plays a role of gas seal, so that carbon monoxide generated in the main cold slag tank 20 can be prevented from reversely channeling to the security cold slag tank 30, potential safety hazards are avoided, and the safe and stable operation of the system is ensured; furthermore, the carbon dioxide can play a role in carrying materials, and is beneficial to smooth discharge of the bottom slag of An Baoleng slag pot 30 after the inner diameter is cooled.
According to an embodiment of the present invention, the temperature of the bottom slag discharged from the safety cold slag pot 30 is not higher than 100 ℃. In order to accurately regulate and control the amount of carbon dioxide introduced into the safety cold slag tank 30, a temperature measuring point (not shown in the figure) is arranged near the safety cold slag tank outlet 31 of the safety cold slag tank 30, and the temperature measuring point is interlocked with the flow of the introduced carbon dioxide (C1) to realize automatic control.
Optionally, according to an embodiment of the present invention, a valve may be disposed on a pipeline between the main cold slag pot outlet 22 of the main cold slag pot 20 and the safety cold slag pot 30 and interlocked with the gasification system, so as to realize the functions of pressure reduction and temperature reduction.
According to an embodiment of the invention, wherein the temperature of the slag in the second temperature range is lower than T 5％ Wherein T is 5％ The chemical reaction temperature is corresponding to the reduction rate of carbon dioxide of 5% in the process of the reduction reaction of carbon and carbon dioxide under the preset reaction conditions.
According to an embodiment of the invention, T 5％ Is the temperature tested according to the method for measuring the chemical reactivity of the national standard (GB/T220-2018) coal to the carbon dioxide.
Because the reactivity of the coal is closely related to the operation condition of the gasification furnace and the coal gasification performance index. The reactivity of the coal to the carbon dioxide is directly related to the temperature, and the whole reactivity is in an increasing trend and tends to 100% along with the rise of the temperature; when the temperature is low, such as 750 ℃ and 800 ℃, the reaction activity is poor, partThe reactivity of the sub-high rank coal is extremely poor and even non-reactive. The national standard prescribes a method for measuring the reactivity of coal, which comprises the following steps: the coal sample is first retorted to remove volatile matters (if the sample is coke, retorting treatment is not needed). Then sieving and selecting the coke slag with a certain granularity (3-6 mm), and loading the coke slag into a reaction tube for heating. After heating to a certain temperature (first heating to 750 ℃ (lignite), or 800 ℃ (bituminous coal, anthracite and coke), then introducing carbon dioxide into the mixture at a certain flow rate every 50 ℃ for reaction with the sample. The carbon dioxide content in the gas after the reaction in the heating process is measured, and the reactivity curve of the temperature and the carbon dioxide reduction rate is drawn by the volume fraction of the carbon dioxide amount reduced into carbon monoxide to the introduced carbon dioxide amount, namely the carbon dioxide reduction rate alpha (%). According to the reactivity curve of temperature-carbon dioxide reduction rate, the change trend of the reactivity of the coal along with the temperature can be known, so as to determine the corresponding chemical reaction temperature T when the carbon dioxide reduction rate is 5 percent 5％ 。
According to the embodiment of the invention, in order to accurately regulate and control the amount of carbon dioxide introduced into the main slag cooling tank 20, a temperature measuring point (not shown in the figure) is arranged near the outlet 22 of the main slag cooling tank 20, and the temperature measuring point is interlocked with the flow of carbon dioxide (C) of the main slag cooling tank 20, so that automatic control is realized.
According to an embodiment of the invention, the chemical reaction temperature T 5％ And the method can be used for determining, providing a reference for the reaction regulation and control of carbon dioxide and the bottom slag and the reasonable selection of cooling temperature, and providing a theoretical basis for the staged cooling of the bottom slag, the quality-dividing utilization of energy and the coordination and matching of the energy and the integral performance of a gasification system.
According to the embodiment of the invention, through a great deal of experimental study and theoretical calculation, when the temperature is higher than 700 ℃, carbon dioxide can be gasified with carbon to generate carbon monoxide. The temperature of slag in the second temperature range, denoted by T, discharged from the main slag pot 20 may also be set to satisfy the following conditions: t is less than or equal to 700 ℃.
According to the embodiment of the invention, by arranging two-stage cooling, the temperature of slag in the second temperature range discharged by the main slag cooling tank 20 is accurately regulated and controlled, and the slag cooling tank is used in coordination with the safety slag cooling tank 30, so that the following advantages are achieved:
firstly, by arranging two-stage cooling in the main slag cooling tank 20, the high Wen De slag can be operated at a relatively high temperature level, such as more than 400 ℃ without directly cooling the high Wen De slag to below 100 ℃, so that the preheating temperature of carbon dioxide is improved, and the gasification reaction of the high Wen De slag and the carbon dioxide in the main slag cooling tank 20 can be enhanced at the higher preheating temperature.
Secondly, although carbon dioxide which is not completely reacted in the main slag pot 20 can enter the gasification furnace to continue the gasification reaction, excessive carbon dioxide can have adverse effect on the gasification reaction and increase the burden of subsequent separation, so that the more carbon dioxide which is introduced into the slag pot is not better. The two stages of slag cooling tanks are connected in series, so that the carbon dioxide introduced into the main slag cooling tank 20 is reduced compared with the case that the bottom slag is directly cooled to be within 100 ℃, and the coordination organization of the slag cooling process and the gasification system is facilitated.
Furthermore, due to T 5％ The temperature corresponding to the carbon dioxide reduction rate obtained by the coal-to-carbon dioxide reaction activity experimental method is 5%, so that the carbon dioxide has poor reactivity under the temperature condition, the probability of generating carbon monoxide is low, and when the bottom slag discharged from the main slag cooling tank 20 is introduced into the safety slag cooling tank, the temperature is continuously reduced, the bottom slag under the temperature condition is not likely to react with carbon dioxide any more, and in the safety slag cooling tank 30, the carbon dioxide only reduces the temperature by physical cooling, absorbs the sensible heat of the bottom slag to reduce the temperature and does not generate gasification reaction with the bottom slag, so that the generation of carbon monoxide can be avoided, and the risk of potential safety hazards caused by carbon monoxide leakage is effectively prevented. Meanwhile, the temperature T of the slag discharged from the main cooling slag pot 20 in the second temperature range is less than or equal to T 5％ The beneficial effects of (2) are also as follows: the amount of carbon dioxide entering the main slag cooling tank 20 can be accurately regulated and controlled, so that the carbon dioxide and high-temperature bottom slag can be gasified as much as possible, further conversion of carbon in the bottom slag is promoted, and the carbon conversion rate of the system is improved.
Fig. 3 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
As shown in fig. 3, in accordance with an embodiment of the present invention, wherein the primary cooling gas C is introduced into a first region of the primary slag pot 20.
The slag cooling method further comprises the following steps: introducing auxiliary cooling gas S into the main slag ladle 20, wherein the auxiliary cooling gas S is introduced into a second region of the main slag ladle; wherein the second region is located higher than the first region, and the temperature in the second region is higher than the temperature in the first region, and the auxiliary cooling gas S adopts one of the following: steam, carbon dioxide, a mixture of carbon dioxide and steam.
According to the embodiment of the invention, the main cooling air C is introduced through the main cooling air injection port 23, the auxiliary cooling air S is introduced through the auxiliary cooling air injection port 24, and the auxiliary cooling air injection port 24 is positioned higher than the main cooling air injection port 23. Since the height of the auxiliary cooling gas injection port 24 is higher than the height of the main cooling gas injection port 23 in the axial direction of the main slag pot 20, the second region is closer to the bottom high temperature region of the furnace, and therefore, the bottom slag temperature in the region where the auxiliary cooling gas injection port 24 is located is high, and therefore, if a method of injecting water vapor is adopted in the region, the water vapor is not easy to condense.
Based on the analysis, the cooling gas can be introduced by adopting the following scheme: carbon dioxide gas is introduced into the main cooling gas injection port 23, so that the strong heat absorption characteristic and stability of the carbon dioxide are fully utilized, and the high Wen De slag is fully cooled before being discharged out of the main slag cooling tank 20; the auxiliary cooling gas injection port 24 can be used for introducing water vapor, so that the characteristic of high bottom slag temperature in the region is fully utilized, and the water vapor is preheated and reacts with carbon in high-temperature bottom slag to generate coal gas active ingredients.
According to the embodiment of the invention, preferably, steam or a mixed gas of steam and carbon dioxide is introduced into the auxiliary cooling gas injection port 24, and when the mixed gas of steam and carbon dioxide is used as the gasifying agent, the synergistic effect of the two gasifying agents can be realized, so that the conversion of carbon is promoted, and the reaction rate and the carbon conversion rate are higher than those of any single gas and carbon.
According to the embodiment of the present invention, heat exchange can be enhanced by introducing the main cooling gas C and the auxiliary cooling gas S into the main slag pot 20. Simultaneously, two kinds of cooling gas are respectively introduced into different temperature areas, and auxiliary cooling gas S is introduced into the high temperature area that is closer to the bottom of the hearth, and auxiliary cooling gas S includes steam, under the prerequisite that realizes steam and carbon dioxide synergism, and promotes the conversion of carbon, can also avoid steam condensation, prevent that bottom sediment from hardening, arrange sediment unsmooth scheduling problem.
Fig. 4 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention.
As shown in fig. 4, slag in the first temperature range comes from the gasifier hearth 10, wherein in the gasifier hearth 10, slag and raw gas in the first temperature range are generated after gasification reaction of the fuel B and the gasifying agent a. The slag cooling method further comprises the following steps:
and carrying out gas-solid separation, cooling and dust removal on the crude gas to obtain clean gas F. Specifically: coarse grain semicoke separated by the gas-solid separator 11 returns to the hearth 10 through the material returning device 12, combustion and gasification reactions occur at the high temperature of 900-1100 ℃, high-temperature bottom slag (900-1100 ℃) which is not completely reacted is introduced into the main slag cooling tank 20 from the bottom of the hearth 10, and is discharged out of the system from the main slag cooling tank outlet 22 at the bottom of the main slag cooling tank 20 after being cooled. The high-temperature dust-containing gas discharged from the gas-solid separator 11 is cooled by a gas cooler 13 and dedusted by a deduster 14 to obtain fly ash D and clean gas F respectively.
The clean gas F is subjected to water gas conversion by a water gas conversion device 15 to obtain a mixed gas of carbon dioxide and hydrogen;
the mixed gas of carbon dioxide and hydrogen is subjected to gas separation by a gas separation device 16 to obtain carbon dioxide product gas I and hydrogen H;
The carbon dioxide product gas I is used as main cooling gas C to be introduced into the main slag cooling tank 20, and the surplus carbon dioxide J is discharged out of the system.
According to the embodiment of the invention, the method is mainly aimed at a coal gasification process taking hydrogen H as a target product. After the clean coal gas F prepared by the coal gasification system is subjected to water gas shift 17 and gas separation 18, a large amount of high-concentration carbon dioxide is obtained, and if the carbon dioxide is not utilized, the emission problem can be caused. Based on good physical and chemical properties of carbon dioxide and in combination with potential carbon dioxide emission problems of a coal gasification system, the high-concentration carbon dioxide separated by the coal gasification system is circulated back to the coal gasification system for cooling high-temperature slag, and the carbon dioxide circulated back to the gasification system can cool the high-temperature bottom slag and participate in gasification reaction, so that recycling of the carbon dioxide is realized. By the method for recycling the carbon dioxide, the carbon dioxide emission is reduced, the recycling of the carbon dioxide is realized, and the problems of low cooling efficiency, potential safety hazards and the like in the slag cooling process in the traditional fluidized bed gasification bottom slag cooling technology are solved.
Fig. 5 is a schematic structural view of a slag cooling apparatus for implementing a slag cooling method according to another embodiment of the present invention. As shown in fig. 5, according to an embodiment of the present invention, wherein:
The primary cold slag pot 20 includes a first primary cold slag pot and a second primary cold slag pot, wherein the first primary cold slag pot and the second primary cold slag pot operate simultaneously; or one of the first main slag cooling tank and the second main slag cooling tank is used as a standby slag cooling tank, which is beneficial to long-period stable operation of fluidized bed gasification.
Another aspect of the present invention provides a slag cooling apparatus for implementing the above slag cooling method, the apparatus referring to fig. 1, as shown in fig. 1, the apparatus comprising: a primary cold slag pot 20, wherein the primary cold slag pot 20 comprises: a main slag pot inlet 21, a main cooling gas injection inlet 23, and a main slag pot outlet 22.
Wherein the primary cold slag pot inlet 21 is used for discharging slag in a first temperature range into the primary cold slag pot; a main cooling gas injection port 23 for introducing main cooling gas into the main slag tank, wherein the main cooling gas is divided into a divided cooling gas flowing upward and a divided sealing gas flowing downward in the main slag tank; the slag in the first temperature range is cooled by the split cooling gas, and then the slag in the second temperature range is obtained; and a primary cold slag pot outlet 22 for discharging slag and split seal gas in a second temperature range, wherein the primary cold slag pot outlet is air-sealed by the split seal gas flowing downwardly past the primary cold slag pot outlet. The slag cooling device is a part of a fluidized bed gasifier and is arranged below a gasifier hearth 10. The main slag cooling tank 20 is used for cooling high-temperature bottom slag generated by the fluidized bed gasifier, bottom slag particles in the main slag cooling tank 20 move downwards in a moving bed mode, the apparent wind speed in the main slag cooling tank 20 ranges from 0.01m/s to 0.25m/s, and the tank body of the slag cooling tank is preferably a cylinder.
The outlet 22 of the main cold slag pot 20 is connected with a valve 25, optionally a slag conveyer, and when slag is required to be discharged, the opening of the valve is regulated or the slag conveyer is started, so that the cooled low-temperature bottom slag is discharged out of the system.
According to the embodiment of the invention, the high-temperature slag in the main cold slag tank is cooled by introducing the cooling gas into the main cold slag tank, and the gas seal effect is achieved on the outlet of the cold slag tank by utilizing part of the cooling gas while the cooling effect is achieved on the high-temperature slag, so that leakage or reverse channeling of gasifying agents, coal gas and cooling gas can be avoided, and the safety problem caused by leakage of combustible gas is prevented. Part of the cooling gas forms upward air flow, and the gasification agent/gas is further prevented from reversely channeling into a slag cooling system while cooling slag, so that the phenomenon of slag bonding caused by the reaction of the gasification agent/gas and high-temperature bottom slag is reduced.
According to an embodiment of the invention, wherein: the main cooling air injection port 23 may be horizontally arranged, and the main cooling air injection port 23 may also be downwardly inclined, with the central axis of the main cooling air injection port 23 having an angle of 5 ° to 60 ° with the horizontal plane. The main cooling air injection port 23 is inclined downwards by a certain angle, so that bottom slag can be prevented from falling into the nozzle pipe in the downward movement process, and meanwhile, the disturbance of the materials at the bottom of the distributor can be enhanced, and the cooled bottom slag can be discharged out of the system.
According to an embodiment of the invention, as shown in fig. 3, wherein: the primary slag ladle 20 further includes a secondary cooling gas injection port 24 provided at a middle upper portion of the primary slag ladle 20 for introducing a secondary cooling gas into a second region of the primary slag ladle. The primary cooling gas is introduced into the first region of the primary slag pot through the primary cooling gas injection port 23. The auxiliary cooling gas injection ports 24 may be uniformly arranged along the circumferential direction of the wall surface of the main slag pot 20, and may be one or more layers, and 2 or more layers may be arranged per layer.
According to the embodiment of the invention, the height of the auxiliary cooling gas injection port 24 is higher than that of the main cooling gas injection port 23 in the axial direction of the main slag pot 20, and the second area is closer to the high temperature area at the bottom of the hearth, so that the temperature of the bottom slag in the area where the auxiliary cooling gas injection port 24 is located is high, and therefore, if a method of injecting water vapor is adopted in the area, the water vapor is not easy to condense.
According to an embodiment of the present invention, as shown in fig. 2, the apparatus further includes: an Baoleng slag pot 30 is used for cooling the slag in the second temperature range to obtain slag in the third temperature range. An Baoleng slag pot 30 and main cold slag pot 29 are both arranged in series.
The safety cold slag pot 30 is also provided with a safety cold slag pot inlet and a safety cold slag pot outlet 31. The safety cold slag tank inlet is communicated with the main cold slag tank outlet and is used for introducing the safety cold slag tank after the slag in the second temperature range is discharged through the main cold slag tank outlet; and a safety cold slag pot outlet 31 for discharging slag in a third temperature range.
According to the embodiment of the invention, the main cold slag pot 20 is communicated with the bottom of the hearth 10 of the fluidized bed gasification furnace through the main cold slag pot inlet 21, the main cold slag pot 20 is communicated with the safety cold slag pot 30 through the main cold slag pot outlet 22, and the main cold slag pot outlet 22 of the main cold slag pot 20 is the safety cold slag pot inlet of the safety cold slag pot 30.
According to an embodiment of the present invention, the safety cold slag pot 30 is provided with a circulating water cooling device, such as a water cooling pipe arranged in the safety cold slag pot 30, for cooling slag in the second temperature range by adopting a circulating water indirect cooling mode.
According to an embodiment of the invention, the security slag pot 30 can be cooled only indirectly by circulating water, or can be cooled by a combination of direct cooling of gas.
Specifically, the security cold slag pot 30 is further provided with a security gas injection port 32, and the security gas injection port 32 is used for introducing security cooling gas C1 into the security cold slag pot so as to perform auxiliary cooling on slag in a second temperature range through the security cooling gas C1 and play a role in air sealing. The security cooling gas C1 can be carbon dioxide or nitrogen, preferably carbon dioxide. The pipeline of the safety cold slag pot outlet 31 is connected with a valve 25, and the cooled bottom slag can be discharged out of the system by opening the valve. Optionally, the valve 25 is a slag conveyor.
According to the embodiment of the invention, the high Wen De slag can be operated at a relatively high temperature level, such as more than 400 ℃ by arranging two-stage cooling in the main slag cooling tank 20, without directly cooling the high Wen De slag to below 100 ℃, so that the preheating temperature of carbon dioxide is increased, and the gasification reaction of the high Wen De slag and the carbon dioxide in the main slag cooling tank 20 can be enhanced at the higher preheating temperature.
Secondly, although carbon dioxide which is not completely reacted in the main slag pot 20 can enter the gasification furnace to continue the gasification reaction, excessive carbon dioxide can have adverse effect on the gasification reaction and increase the burden of subsequent separation, so that the more carbon dioxide which is introduced into the slag pot is not better. The two stages of slag cooling tanks are connected in series, so that the carbon dioxide introduced into the main slag cooling tank 20 is reduced compared with the case that the bottom slag is directly cooled to be within 100 ℃, and the coordination organization of the slag cooling process and the gasification system is facilitated.
According to an embodiment of the present invention, as shown in fig. 4, slag in the first temperature range is derived from a gasifier hearth, wherein slag and raw gas in the first temperature range are generated after gasification reaction of fuel and gasifying agent in the gasifier hearth.
The slag cooling device also comprises a raw gas treatment system, a water gas conversion device 15 and a gas separation device 16. The crude gas treatment system is used for obtaining clean gas after gas-solid separation, cooling and dust removal of the crude gas; a water gas shift device 15 for shifting the clean gas by water gas to obtain a mixed gas of carbon dioxide and hydrogen; and a gas separation device 16 for separating the mixed gas of the carbon dioxide and the hydrogen to obtain carbon dioxide product gas, wherein an outlet of the gas separation device is communicated with a main cooling gas injection port, and the carbon dioxide product gas is used as main cooling gas and is introduced into the main slag cooling tank.
The crude gas treatment system comprises a gas-solid separator 11, a returning charge device 12, a gas cooler 13 and a dust remover 14. The gas-solid separator 11 is used for returning the separated coarse-particle semicoke to the hearth 10 through the returning charge device 12. The high-temperature dust-containing gas discharged from the gas-solid separator 11 is cooled by a gas cooler 13 and dedusted by a deduster 14 to obtain fly ash D and clean gas F respectively.
According to the embodiment of the invention, the device is mainly aimed at a coal gasification process taking hydrogen H as a target product. The carbon dioxide separated by the coal gasification system is circulated back to the coal gasification system for cooling high-temperature slag, and the part of carbon dioxide circulated back to the gasification system can cool the high-temperature bottom slag and participate in gasification reaction, so that the recycling of the carbon dioxide is realized.
According to the embodiment of the invention, as shown in fig. 5, the main cold slag pot 20 comprises a first main cold slag pot and a second main cold slag pot, a slag discharge pipe at the bottom of the hearth is divided into two parts, each slag discharge pipe is connected with one set of cold slag pot, and the first main cold slag pot and the second main cold slag pot can operate at the same time; or one of the first main slag cooling tank and the second main slag cooling tank is used as a standby slag cooling tank, which is beneficial to long-period stable operation of fluidized bed gasification.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the invention thereto, but to limit the invention thereto, and any modifications, equivalents, improvements and equivalents thereof may be made without departing from the spirit and principles of the invention.
Claims (15)
1. A method of cooling slag comprising:
discharging slag in a first temperature range into a primary cold slag pot, the primary cold slag pot comprising a primary cooling gas injection inlet;
introducing main cooling gas into the main slag cooling tank through the main cooling gas injection port, wherein the main cooling gas is divided into upward flowing divided cooling gas and downward flowing divided sealing gas in the main slag cooling tank, and the main cooling gas comprises carbon dioxide cooling gas;
Cooling the slag in the first temperature range through the split cooling gas to obtain slag in a second temperature range;
discharging the slag and the split-flow sealing gas in the second temperature range along a main cold slag pot outlet of the main cold slag pot, wherein the split-flow sealing gas downwards flows through the main cold slag pot outlet to play a gas sealing role on the main cold slag pot outlet;
discharging the slag in the second temperature range through the outlet of the main cold slag tank, then introducing the slag into the safety cold slag tank, and introducing safety cooling gas into the safety cold slag tank;
wherein the security cooling gas comprises carbon dioxide cooling gas; the temperature of the slag in the second temperature range is lower than T 5% Wherein said T is 5% The chemical reaction temperature is corresponding to the reduction rate of carbon dioxide of 5% in the process of the reduction reaction of carbon and carbon dioxide under the preset reaction conditions.
2. The slag cooling method of claim 1, wherein:
after the slag in the first temperature range is discharged into the main slag cooling tank, the slag is uniformly distributed downwards along the main slag cooling tank;
and the upward flowing split cooling gas is in countercurrent contact with the slag in the first temperature range, and cooling is carried out on the slag in the first temperature range.
3. The slag cooling method of claim 1, wherein cooling the slag in the first temperature range with the split cooling gas comprises:
and carrying out chemical cooling on the slag in the first temperature range by utilizing chemical endothermic reaction between the split cooling gas and residual carbon in the slag in the first temperature range while carrying out physical cooling on the slag in the first temperature range through the split cooling gas.
4. A slag cooling method according to claim 1 or 3, further comprising:
and cooling the slag in the second temperature range through the security cold slag tank to obtain slag in a third temperature range.
5. The slag cooling method of claim 4, wherein cooling the slag in the second temperature range by the safety slag cooling tank comprises:
introducing security cooling gas into the security cold slag tank so as to cool slag in the second temperature range through the security cooling gas; and
in the security slag cooling tank, the slag in the second temperature range is cooled by adopting a circulating water indirect cooling mode.
6. A slag cooling method according to claim 3, wherein the primary cooling gas is channeled into a first region of the primary slag ladle;
the slag cooling method further comprises the following steps:
introducing auxiliary cooling gas into the main slag cooling tank, wherein the auxiliary cooling gas is introduced into a second region of the main slag cooling tank;
wherein the second zone is located higher than the first zone and the temperature in the second zone is higher than the temperature in the first zone, the secondary cooling gas adopts one of the following: steam, carbon dioxide, a mixture of carbon dioxide and steam.
7. The slag cooling method of claim 1, wherein:
the slag in the first temperature range is from a gasifier hearth, wherein in the gasifier hearth, the fuel and the gasifying agent are subjected to gasification reaction to generate slag and raw gas in the first temperature range;
the slag cooling method further comprises the following steps:
the crude gas is subjected to gas-solid separation, cooling and dust removal to obtain clean gas;
the clean gas is subjected to water gas conversion to obtain a mixed gas of carbon dioxide and hydrogen;
separating the mixed gas of the carbon dioxide and the hydrogen to obtain carbon dioxide product gas;
And introducing the carbon dioxide product gas into the main slag cooling tank as the main cooling gas.
8. The slag cooling method of claim 1, wherein:
the main cold slag tank comprises a first main cold slag tank and a second main cold slag tank, wherein the first main cold slag tank and the second main cold slag tank run simultaneously; or alternatively
And taking one of the first main slag cooling tank and the second main slag cooling tank as a standby slag cooling tank.
9. A slag cooling apparatus for implementing the slag cooling method of any one of claims 1 to 8, comprising:
a primary cold slag pot, wherein the primary cold slag pot comprises:
a primary cold slag pot inlet for discharging slag within a first temperature range into the primary cold slag pot;
a main cooling gas injection port for introducing main cooling gas into the main slag cooling tank, wherein the main cooling gas is divided into a divided cooling gas flowing upwards and a divided sealing gas flowing downwards in the main slag cooling tank; cooling the slag in the first temperature range through the split cooling gas to obtain slag in a second temperature range, wherein the main cooling gas comprises carbon dioxide cooling gas;
the main cold slag pot outlet is used for discharging slag in the second temperature range and the split-flow sealing gas, wherein the split-flow sealing gas downwards flows through the main cold slag pot outlet to play a gas sealing role on the main cold slag pot outlet;
Security cold slag pot, security cold slag pot includes:
the safety cold slag tank inlet is communicated with the main cold slag tank outlet and is used for discharging slag in the second temperature range through the main cold slag tank outlet and then introducing the slag into the safety cold slag tank;
the safety gas injection port is used for introducing safety cooling gas into the safety cold slag tank;
wherein the security cooling gas comprises carbon dioxide cooling gas; the temperature of the slag in the second temperature range is lower than T 5% Wherein said T is 5% The chemical reaction temperature is corresponding to the reduction rate of carbon dioxide of 5% in the process of the reduction reaction of carbon and carbon dioxide under the preset reaction conditions.
10. The slag cooling device of claim 9, wherein:
and the security cold slag pot is used for cooling the slag in the second temperature range to obtain slag in a third temperature range.
11. The slag cooling device of claim 10, wherein:
the security slag cooling tank is provided with a circulating water cooling device and is used for cooling slag in the second temperature range in an indirect circulating water cooling mode.
12. The slag cooling device of claim 11, wherein the safety slag cooling tank is further provided with:
An outlet of the security cold slag pot is used for discharging slag in the third temperature range;
and cooling the slag in the second temperature range through the security cooling gas.
13. The slag cooling device of claim 9, wherein:
the slag in the first temperature range comes from a gasification furnace hearth, wherein in the gasification furnace hearth, the fuel and the gasifying agent perform gasification reaction to generate slag and raw gas in the first temperature range;
the slag cooling device further comprises:
the crude gas treatment system is used for obtaining clean gas after gas-solid separation, cooling and dust removal of the crude gas;
the water gas conversion device is used for converting the clean gas into a mixed gas of carbon dioxide and hydrogen after water gas conversion;
the gas separation device is used for separating the mixed gas of the carbon dioxide and the hydrogen to obtain carbon dioxide product gas, wherein an outlet of the gas separation device is communicated with the main cooling gas injection inlet, and the carbon dioxide product gas is used as the main cooling gas to be introduced into the main slag cooling tank.
14. The slag cooling device of claim 9, wherein:
the main cold slag tank comprises a first main cold slag tank and a second main cold slag tank, wherein the first main cold slag tank and the second main cold slag tank run simultaneously; or alternatively
And taking one of the first main slag cooling tank and the second main slag cooling tank as a standby slag cooling tank.
15. The slag cooling device of claim 9, wherein:
the included angle between the central axis of the main cooling gas injection port and the horizontal plane is 5-60 degrees.
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| CN110387267A (en) * | 2018-04-17 | 2019-10-29 | 中国科学院工程热物理研究所 | Bottom ash treatment device and bottom ash treatment method for fluidized-bed gasification furnace |
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