CN112760136B - Circulating fluidized bed gasification device and circulating fluidized bed gasification method - Google Patents
Circulating fluidized bed gasification device and circulating fluidized bed gasification method Download PDFInfo
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- CN112760136B CN112760136B CN202011490349.XA CN202011490349A CN112760136B CN 112760136 B CN112760136 B CN 112760136B CN 202011490349 A CN202011490349 A CN 202011490349A CN 112760136 B CN112760136 B CN 112760136B
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- fluidized bed
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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
- C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
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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
- C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
- C10J3/56—Apparatus; Plants
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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
- C10J2200/00—Details of gasification apparatus
- C10J2200/15—Details of feeding means
- C10J2200/152—Nozzles or lances for introducing gas, liquids or suspensions
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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
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0953—Gasifying agents
- C10J2300/0959—Oxygen
Abstract
The invention provides a circulating fluidized bed gasification device and a circulating fluidized bed gasification method. The circulating fluidized bed gasification apparatus includes: the gasification furnace comprises a gasification furnace hearth (1), a cyclone separator (2) and a material returning device, wherein an air distribution device is arranged at the lower part of the gasification furnace hearth (1); the air distribution device comprises a plurality of gasifying agent nozzles (3), and at least two gasifying agent nozzles (3) in the gasifying agent nozzles (3) are arranged at different vertical heights. By adopting the circulating fluidized bed gasification device and the circulating fluidized bed gasification method, the air distribution uniformity is improved, and the carbon conversion rate of the system is high.
Description
Technical Field
The invention relates to the technical field of fuel gasification, in particular to a circulating fluidized bed gasification device and a circulating fluidized bed gasification method.
Background
As a clean coal conversion technology, the circulating fluidized bed coal gasification technology has a material circulation loop with high circulation quantity, prolongs the retention time of solid materials in a furnace, has the advantages of strong coal adaptability, full gas-solid mixing, high gasification reaction rate, uniform reaction temperature and the like, and is widely applied to the fields of industrial gas and synthetic ammonia.
The above-mentioned advantages of a circulating fluidized bed depend to a large extent on the design of the gas distributor. The gas distributor is arranged at the lower part of the gasification furnace, plays the roles of uniformly distributing gas and supporting solid particles, and whether the structural design of the gas distributor is reasonable or not greatly influences the fluidization quality of the hearth of the gasification furnace, so that the temperature distribution, the reaction rate and the gas components are influenced. The existing fluidized bed gas distributor mostly adopts the form of an air distribution plate, small holes are arranged on the air distribution plate, and a gasification agent enters a reactor through the small holes to react with solid materials and simultaneously plays a role of a fluidized bed layer as a fluidized medium. For small-scale gasification furnaces, the air distribution mode can ensure that the gasification agent has higher speed when passing through the bottom of the bed layer, and can realize good fluidization of the bed layer and full contact of gas and solid. After the production capacity of a single gasification furnace is improved, the diameter of the air distribution plate is increased, the air distribution plate needs to bear dozens of tons of weight in the hot start, operation fluctuation and fire suppression processes of the gasification furnace, the thermal deformation is easily generated, the structure of the air distribution plate is damaged, and the normal operation is influenced. On the other hand, all oxygen-containing gasifying agents enter the furnace through the air distribution plate of the gasification furnace, and the centralized oxygen supply mode easily causes local high temperature and coking of materials in the furnace. In order to ensure safe operation, the oxygen concentration at the bottom of the gasifier is generally controlled to operate in a lower range, and the bottom temperature does not reach the optimal conversion temperature of ash, so that the carbon content of the bottom slag of the gasifier is higher, and the carbon conversion rate and the energy utilization rate of the system are low.
In addition, the bed layer of the circulating fluidized bed is violently back-mixed in the operation process, the dense-phase zone at the bottom contains a large amount of fine-particle circulating semi-coke, the fine-particle semi-coke is discharged together with coarse particles in the deslagging process, and the carbon content of the whole bottom slag is higher because the carbon content of the fine-particle semi-coke is higher than that of the coarse particles.
It can be seen that the existing gas distributor mainly has the following technical defects:
(1) after the production capacity of a single gasification furnace is improved, the thermal deformation is easily generated in the hot start, operation fluctuation and fire suppression processes of the gasification furnace, so that the structure of the air distribution plate is damaged, and the device cannot normally operate.
(2) The bottom temperature of the gasification furnace does not reach the optimal conversion temperature of ash slag, and meanwhile, the circulating semicoke content in the bottom slag of the gasification furnace is high, so that the carbon content of the bottom slag is high, and the carbon conversion rate of a system is low.
(3) The wind distribution structure is complex and the resistance is large.
Therefore, there is a need to develop a new type circulating fluidized bed gasification device, which can reduce the air distribution resistance and the carbon content of the bottom slag while optimizing the air distribution structure, improve the carbon conversion rate and the cold gas efficiency of the system, and improve the stability of the system operation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art at least partially and provides a circulating fluidized bed gasification device and a circulating fluidized bed gasification method for improving the air distribution uniformity.
The invention also aims to provide a circulating fluidized bed gasification device and a circulating fluidized bed gasification method, which can increase the retention time of bottom slag at the bottom of a gasification furnace, reduce the carbon content of the bottom slag and improve the carbon conversion rate of a system.
The invention also aims to provide a circulating fluidized bed gasification device and a circulating fluidized bed gasification method, which have the advantages of small air distribution resistance, simple structure and capability of improving the operation stability of the gasification device.
To achieve one of the above objects or purposes, the technical solution of the present invention is as follows:
a circulating fluidized bed gasification apparatus, comprising: the gasification furnace comprises a gasification furnace hearth, a cyclone separator and a material returning device, wherein an air distribution device is arranged at the lower part of the gasification furnace hearth; the air distribution device comprises a plurality of gasifying agent nozzles, and at least two gasifying agent nozzles in the gasifying agent nozzles are arranged at different vertical heights.
According to a preferred embodiment of the present invention, the plurality of gasification agent ports are divided into a plurality of gasification agent port groups, each of the plurality of gasification agent port groups includes at least two gasification agent ports, the gasification agent ports in each of the plurality of gasification agent port groups are disposed at the same vertical height, and each of the plurality of gasification agent port groups is disposed at a different vertical height.
According to a preferred embodiment of the invention, the plurality of gasification agent nozzle groups are distributed at equal intervals or unequal intervals.
According to a preferred embodiment of the invention, the gasification agent spouts in each gasification agent spout group are distributed at equal intervals or at unequal intervals.
According to a preferred embodiment of the present invention, the gasification agent ports in each gasification agent port group are distributed on a circle, and the extension of the center line of the gasification agent ports in at least one gasification agent port group does not pass through the center of the circle.
According to a preferred embodiment of the present invention, the extension line of the center line of the gasification agent port located in the uppermost gasification agent port group does not pass through the center of the circle.
According to a preferred embodiment of the present invention, the center line of the gasifying agent nozzle is at an angle between the tangent line of the intersection of the circle and the center line of the gasifying agent nozzle, and the angle is between 10 and 85 degrees.
According to a preferred embodiment of the invention, said angle is comprised between 20 and 30 °.
According to a preferred embodiment of the invention, the angle between the gasification agent nozzle and the horizontal plane is 8-20 °.
According to a preferred embodiment of the present invention, the number of the gasifying agent spouts in each gasifying agent spout group is at least 3, and the gasifying agent spouts are uniformly distributed along the circumference.
According to a preferred embodiment of the present invention, the air distribution device further comprises a gas distributor disposed below the plurality of gasifying agent nozzles.
According to a preferred embodiment of the invention, the gas distributor comprises a gas inlet main pipe and a plurality of gasifying agent nozzles, one end of each gasifying agent nozzle is communicated with the gas inlet main pipe, the other end of each gasifying agent nozzle is provided with a gas outlet, and the plurality of gasifying agent nozzles are arranged in a star shape.
According to a preferred embodiment of the present invention, each gasifying nozzle unit is independently provided with a windbox and a valve.
According to a preferred embodiment of the invention, the lower part of the hearth of the gasification furnace is provided with a conical section, and the plurality of gasification agent nozzles of the air distribution device are arranged on the conical section.
According to a preferred embodiment of the invention, the cone angle of the cone segments is 30-60 °.
According to a preferred embodiment of the invention, the angle between the center line of the gasification agent nozzle and the wall surface of the cone section is 0-85 °.
According to a preferred embodiment of the invention, the gasifying agent nozzles are welded to the walls of the gasifier chamber.
According to a preferred embodiment of the invention, one end of the gasifying agent nozzle extends outside the gasification furnace hearth, and the other end is arranged in the wall of the gasification furnace hearth in a concave manner.
According to a preferred embodiment of the invention, said other end is 20-50mm from the inner surface of the wall of the gasifier chamber.
According to a preferred embodiment of the invention, the bottom of the gasifier hearth is provided with a slag discharge opening, and a steam inlet is provided on a wall of the gasifier hearth above the slag discharge opening.
According to another aspect of the present invention, there is also provided a circulating fluidized bed gasification method using the circulating fluidized bed gasification apparatus according to any one of the preceding embodiments, the oxygen concentration of each gasification agent nozzle group being different.
According to a preferred embodiment of the invention, the oxygen concentration of each gasification nozzle group is gradually increased from bottom to top.
According to a preferred embodiment of the invention, the gas forms a rotational flow after entering the gasification furnace through the air distribution device.
According to a preferred embodiment of the invention, the gas velocity at the outlet of the gasifying agent nozzles is 30-70m/s, and the bed velocity between the gasifying agent nozzles with different heights is maintained above 3.5 m/s.
According to a preferred embodiment of the invention, the exit gas velocity of the gasifying nozzle is 35-60 m/s.
According to the circulating fluidized bed gasification device and the circulating fluidized bed gasification method, the graded air distribution is adopted, so that the air distribution uniformity is improved, the air distribution structure is simplified, and the operation stability of the device is improved. The staged air distribution and the moving bed slag discharge increase the retention time of the bottom slag at the bottom of the gasification furnace, reduce the carbon content of the bottom slag and improve the carbon conversion rate of the system. In addition, the invention distributes wind through the wind pipe, and has small resistance, low energy consumption and low processing and installation cost.
Drawings
FIG. 1 is a schematic view of a circulating fluidized bed gasification apparatus according to an embodiment of the present invention, in which the structure of an air distribution device is shown;
FIG. 2 is a schematic view of a circulating fluidized bed gasification apparatus according to an embodiment of the present invention, in which the structure of an air distribution device is shown;
FIG. 3 is a schematic view of a circulating fluidized bed gasification apparatus according to an embodiment of the present invention, in which the structure of an air distribution device is shown; and
fig. 4 is a schematic sectional view taken along the section a-a in fig. 1, in which a top view of the wind distribution device is shown.
Detailed Description
Exemplary embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings, wherein like or similar reference numerals denote like or similar elements. Furthermore, 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 disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in schematic form in order to simplify the drawing.
According to the inventive concept of the present invention, there is provided a circulating fluidized bed gasification apparatus including: the gasification furnace comprises a gasification furnace hearth, a cyclone separator and a material returning device, wherein an air distribution device is arranged at the lower part of the gasification furnace hearth; the air distribution device comprises a plurality of gasifying agent nozzles, and at least two gasifying agent nozzles in the gasifying agent nozzles are arranged at different vertical heights.
By adopting the method of introducing the gasifying agent into the gasification furnace in different heights in a grading manner, on one hand, the oxygen-containing gas is dispersed into the gasification furnace through multiple points, so that the uniform distribution of a temperature field at high temperature in a dense-phase region at the bottom of the gasification furnace is ensured, the coking caused by local high temperature in the gasification furnace is avoided, and the carbon content of bottom slag is reduced; on the other hand, the axial speed of the dense-phase region of the gasification furnace can be adjusted by adjusting the introduction amount of the gasification agents with different heights, so that the effective separation of coarse particles and fine particles is realized, the content of circulating semicoke in the bottom slag is reduced, and the carbon content of the bottom slag is reduced. Specifically, the gasification agent nozzle is adopted for air distribution. Fig. 1 is a schematic view of a circulating fluidized bed gasification apparatus according to an embodiment of the present invention, in which the structure of an air distribution device is shown, as shown in fig. 1, the circulating fluidized bed gasification apparatus includes: a gasification furnace hearth 1; a cyclone 2; a material returning device; and the air distribution device is characterized in that the gasification furnace hearth 1, the cyclone separator 2 and the material returning device are sequentially connected. The lower part of the gasification furnace hearth 1 is provided with a conical section, the top part is provided with a coal gas outlet, and the cyclone separator 2 is communicated with the coal gas outlet of the gasification furnace hearth 1. According to the invention, the air distribution device comprises a plurality of gasifying agent nozzles 3, the gasifying agent nozzles 3 are arranged on the conical section, and at least two gasifying agent nozzles 3 in the gasifying agent nozzles 3 are arranged on different vertical heights. As shown in fig. 1, the plurality of gasification agent ports 3 are divided into a plurality of gasification agent port groups, each of which includes at least two gasification agent ports 3, the gasification agent ports 3 in each of the gasification agent port groups are arranged at the same vertical height, and each of the plurality of gasification agent port groups is arranged at a different vertical height. In fig. 1, the air distribution device comprises three gasifying agent nozzle groups.
The lower part of the gasification furnace hearth 1 is provided with a conical section, the cone angle theta of the conical section is a key factor influencing the flow field of the gasification furnace and slag discharge, the too large cone angle is not beneficial to forming rotational flow and influencing the flow field of the gasification furnace, and simultaneously, ash residues are accumulated on the conical section to cause unsmooth slag discharge. The cone angle is too small, so that the height of a dense phase zone in the gasification furnace is increased, and the bed resistance is increased. In view of optimizing the flow field and smoothly discharging slag, the taper angle theta is generally 30-60 degrees, for example, when theta is 40-50 degrees, the uniform distribution of the flow field and the smooth falling of the ash slag can be realized.
The gasifying agent nozzles are arranged in the dense-phase zone at the lower part of the gasification furnace, are arranged at different heights along the axial direction of the gasification furnace and are used for introducing the gasifying agent. Through setting up the gasification agent spout, the required gasification agent of gasification gets into from the gasifier co-altitude not, and this kind of mode of admitting air can adjust the gasification agent distribution proportion in a flexible way, has reduced the oxygen content of each gasification agent entry on the one hand, has effectively avoided the high temperature region to the risk of slagging scorification has been reduced, and on the other hand has strengthened the flow and the backmixing of in-bed material, accelerates the material mass transfer heat transfer, is favorable to going on fast of gasification reaction.
According to different process conditions, 2-4 gasification agent nozzle groups can be arranged, the gasification agent nozzle groups are axially distributed along the gasification furnace when being arranged in multiple groups, and the multiple gasification agent nozzle groups can be distributed at equal intervals or non-equal intervals according to different process conditions. The distance setting principle is that oxygen entering the gasification furnace through the lower gasification agent nozzle is completely consumed at the adjacent upper gasification agent nozzle, and the oxygen concentration of each group of gasification agent nozzles is gradually increased from bottom to top in the gasification furnace hearth lower gasification agent nozzle area, for example, when 3 groups are designed, the oxygen concentration distribution of each group from bottom to top is preferably 20%, 30% and 50%. The gasifying agent spouts 3 in each gasifying agent spout group can be distributed at equal intervals or unequal intervals. The number of the gasification agent spouts 3 in each gasification agent spout group is at least 3, for example, 3 to 8, and the gasification agent spouts 3 are uniformly distributed along the circumference, so that the gasification agent spouts 3 in each gasification agent spout group are distributed on a circle. In order to make the gasifying agent better drive the bed layer to fluidize and realize uniform flow, the gas entering the gasification furnace is required to form rotational flow, so that at least one group of gasifying agent nozzle center lines and the center line and the tangent line of the circle (such as the tangent line of the circumference of the gasification furnace) are arranged at a certain angle beta, namely the extension line of the center line of the gasifying agent nozzle 3 on the circle does not pass through the center of the circle, and the angle beta is usually 10-85 degrees, which is shown in figure 4. The gas-solid materials with too small beta value can wash the furnace wall, which not only influences the uniformity of the flow field, but also can cause the damage of refractory materials in the furnace, the too large beta value causes the accumulation of the materials near the wall surface to form a dead zone because the airflow is far away from the wall surface, and the beta value is preferably 20-30 degrees in consideration of the uniform distribution of the flow field. Preferably, the central line of the gasification agent nozzle of at least the uppermost group is arranged at a certain angle beta with the radial tangent of the gasification furnace. In an alternative embodiment, the angle beta between the central line of each group of gasifying agent nozzles and the radial tangent of the gasification furnace is gradually increased from top to bottom. In an optional embodiment, the central line of the uppermost group of gasifying agent nozzles and the radial tangent of the gasification furnace form an angle beta, and the central lines of the other layers of gasifying agent nozzles are perpendicular to the radial tangent of the gasification furnace and are arranged in the radial direction. In order to make the gas-solid contact more sufficient, a certain angle alpha (upward or downward) can be arranged between the gasifying agent nozzle and the wall surface of the gasification furnace at the gasifying agent nozzle, when the angle alpha is upward, the value is 0-85 degrees, preferably 5-45 degrees and further preferably 8-20 degrees are considered from the angle of uniform flow field distribution; when alpha is downward, the value is 00-45 degrees, and preferably 0-30 degrees. In order to provide sufficient power for the gasifying agent nozzles and prevent the material in the bed from flowing backwards, the gas velocity at the outlet of the gasifying agent nozzles is maintained at 30-70m/s, and the gas velocity is preferably 35-60m/s in view of reducing the resistance of the gasifying agent nozzles and prolonging the service life of the gasifying agent nozzles in combination with the distribution of the flow field of the gasification furnace. In order to better realize the effective separation of coarse particles and fine particles and reduce the content of the fine particles in the bottom slag, the bed velocity between gasification agent nozzles with different heights in the furnace is maintained to be more than 3.5 m/s.
In view of the circulating fluidized bed gasification apparatus of the foregoing embodiment, the present invention also provides a circulating fluidized bed gasification method in which the oxygen concentration of each gasification agent nozzle group is different. Advantageously, the oxygen concentration of each gasification agent nozzle group increases gradually from bottom to top, for example, when 3 groups of gasification agent nozzle groups are designed, the oxygen concentration of each group from bottom to top is respectively 10% -30%, 20% -40% and 40% -60%, and the oxygen concentration of the gasification agent nozzle group positioned below is lower than that of the gasification agent nozzle group positioned above. For example, in one embodiment, the oxygen concentration distribution from bottom to top is preferably 20%, 30%, and 50%.
According to a preferred embodiment of the invention, the gas forms a rotational flow after entering the gasification furnace through the air distribution device, so that the gasification agent can better drive the bed layer to fluidize, and uniform flow is realized, and the rotational flow is formed by the following technical means: at least one group of gasification agent nozzle central lines and the central line and the tangent line of the circle (such as the tangent line of the circumference of the gasification furnace) are arranged with a certain angle beta, namely the extension line of the central line of the gasification agent nozzle 3 on the circle does not pass through the center of the circle, and the angle beta is usually 10-85 degrees.
According to a preferred embodiment of the present invention, the gas velocity at the outlet of the gasifying nozzle is 30-70m/s, and the velocity between the gasifying nozzles of different heights is maintained above 3.5 m/s. The gas velocity at the outlet of the gasifying agent nozzle enables the gasifying agent nozzle to provide enough power and simultaneously prevents the material in the bed from flowing backwards, and the gas velocity is preferably 35-60m/s in consideration of reducing the resistance of the gasifying agent nozzle and prolonging the service life of the gasifying agent nozzle by combining the flow field distribution of the gasification furnace. By maintaining the velocity between the gasification agent nozzles with different heights to be more than 3.5m/s, the effective separation of coarse particles and fine particles is better realized, and the content of the fine particles in the bottom slag is reduced.
A single gasifying agent nozzle and the gasification furnace are fixed in a welding mode, one end of the gasifying agent nozzle 3 extends out of the hearth 1 of the gasification furnace, the other end of the gasifying agent nozzle extends towards the gasification furnace, and in order to avoid abrasion, the other end of the gasifying agent nozzle is arranged in the wall (such as the inner wall of the refractory material of the gasification furnace) of the hearth 1 of the gasification furnace in a concave mode and is retracted 20-50mm away from the inner wall of the refractory material of the gasification furnace. In order to ensure that the gasifying agents are uniformly distributed on each gasifying agent nozzle, each group of gasifying agent nozzles are independently provided with an air box and a valve, and the flow of the gasifying agents on each gasifying agent nozzle can be independently controlled.
Fig. 2 shows a schematic view of a circulating fluidized bed gasification apparatus according to another embodiment of the present invention. The difference from the embodiment shown in fig. 1 is that: the bottom of the gasification furnace hearth 1 is provided with a slag discharge port, and a steam inlet is arranged on the wall of the gasification furnace hearth 1 above the slag discharge port. The lower part of the gasification furnace is provided with a steam inlet, during slag discharging, steam and ash residue exchange heat in a countercurrent mode, the amount of introduced steam is determined according to the amount of the ash residue of the gasification furnace and the diameter of a slag discharging port, the speed of the steam in the slag discharging port is maintained to be 0.2-0.4m/s, so that a good heat exchange effect is achieved, and meanwhile, the ash residue is ensured to have good fluidity and can be discharged smoothly. This scheme has both increased the mobility of lime-ash for arrange the sediment more smoothly, retrieved the lime-ash sensible heat again, reduced the sediment temperature of arranging, improved the system efficiency.
Fig. 3 shows a schematic view of a circulating fluidized bed gasification apparatus according to another embodiment of the present invention. The difference from the embodiment shown in fig. 1 is that: the air distribution device further comprises a gas distributor 4, and the gas distributor 4 is arranged below the plurality of gasifying agent nozzles 3. The bottom of the gasification furnace is provided with a gas distributor, and ash slag is discharged from the side surface of the lower part of the gasification furnace. One part of the gasifying agent (steam, air/oxygen) enters the gasification furnace through the gas distributor, and the other part of the gasifying agent (steam, oxygen/air) enters the gasification furnace through the gasifying agent nozzle. The composition and proportion of the gas distributor and the gasifying agents at each layer of gasifying agent nozzle are adjusted in real time according to the height of the bed layer and the temperature of the gasification furnace. After the gas distributor is arranged, in the starting stage of starting, the starting can be carried out in a manner of ignition under the bed (the ignition burner is arranged at the lower part of the gas distributor, hot flue gas generated by the ignition burner enters the gasification furnace through the gas distributor to heat bed materials), and meanwhile, the gas distributor plays a role in uniformly distributing air, so that the flow field in the furnace can be effectively improved, and the mass transfer and heat transfer of the materials are facilitated.
The gas distributor is positioned at the lower part of the gasification furnace and is used for dispersing the gasification agent entering from the lower part of the gasification furnace, ensuring that the gasification agent uniformly disperses at a certain speed and enters the furnace to participate in gasification reaction and maintain fluidization of materials in the gasification furnace. On the other hand, the support bed material is used for supporting bed materials in the processes of starting, running and suppressing fire of the gasification furnace. In order to have enough strength to support bed materials in the ignition starting, operation and fire-pressing processes of the gasification furnace, the invention adopts a lotus-shaped gas distributor, the gas distributor comprises a main air inlet pipe and a plurality of gasification agent nozzles, one end of each gasification agent nozzle is communicated with the main air inlet pipe, the other end of each gasification agent nozzle is provided with a gas outlet, and the plurality of gasification agent nozzles are arranged in a star shape. The gas distributor 4 may also comprise a horizontal plate and a plurality of gas holes are provided in said horizontal plate.
The air distribution structure of the gasification furnace combines the gasification characteristics of the fluidized bed, the detailed design is carried out from the perspective of optimizing the whole flow field in the gasification furnace, the gas flow direction is favorable for the mixing of the bed layer, and the flow field is more uniform. Further, the method provided by the present invention uses the above gasification furnace, so that coal and gasification agent are subjected to gasification reaction in the reactor, during the gasification reaction, gasification agents, such as steam, oxygen, etc., are respectively introduced into different regions in the reactor through gasification agent nozzles (or a combination of gasification agent nozzles and a gas distributor, see the embodiment of fig. 3), the introduced gas reacts with coal to generate heat for gasification reaction, and according to different heat requirements for reaching optimal reaction degree of gasification reaction in different gasification reaction regions in the reactor, oxygen-containing gas is respectively introduced into each region to realize heat coupling of each reaction region, thereby ensuring that each gasification reaction region is carried out according to optimal reaction degree. The gasification furnace is adopted for gasification, so that the flow field in the reactor is uniform, local high temperature is not easy to occur, and the deterioration of the fluidization state caused by mutual adhesion and agglomeration of coal ash particles due to overhigh local temperature of a bed layer is effectively avoided, thereby ensuring the continuous and stable operation of the gasification furnace. Meanwhile, the gasification process adopts a moving bed deslagging mode, ash and slag are fully contacted with an oxygen-containing gasification agent at the lower part of the gasification furnace to generate combustion and gasification reactions, the carbon content of the ash and slag can be effectively reduced, and the overall carbon conversion rate of the system is improved.
The specific process is implemented (as shown in figure 1), coal powder with qualified granularity enters the gasifier through a feed inlet of the gasifier, a gasifying agent (steam, oxygen/air) enters the gasifier through a gasifying agent nozzle, dust-containing coal gas generated after the coal reacts with the gasifying agent is discharged from an upper outlet of the gasifier, and generated ash is discharged through a lower slag discharge port of the gasifier. In the whole gasification process, the composition and proportion of the gasification agent at each layer of gasification agent nozzle are adjusted in real time according to the height of the bed layer and the temperature of the gasification furnace, so that the uniformity of the temperature and the flow field in the furnace is ensured. By adopting the wind distribution mode, the wind distribution structure is simplified, and the resistance of the wind distribution system is reduced.
At the lower part of the gasification furnace, a certain angle beta is arranged between the central line of at least one group of gasification agent nozzles positioned at the top and the radial tangent line of the gasification furnace, and the beta is an acute angle, so that gasification agent airflow entering the bottom of the gasification furnace through the group of gasification agent nozzles forms a tangent circle, the tangent circle enables materials at the lower part of the gasification furnace to be in a rotational flow state, because the internal pressure of the rotational flow is low, large particles are gathered to the axis area of the gasification furnace at the bottom of the gasification furnace, and materials with smaller particles are distributed in a relatively peripheral area and supported by the gasification agent flowing upwards at the bottom, so that the materials can not fall into the bottom of the gasification furnace, and meanwhile, gasification reaction is carried out between the fine particles and the gasification agent, so that the content of the fine particles in bottom slag is reduced, and because the carbon content of the fine particles is greater than that of the coarse particles, the whole carbon content in the bottom slag is reduced, and the whole carbon conversion rate of a system is improved.
In conclusion, according to the circulating fluidized bed gasification device and the circulating fluidized bed gasification method, the graded air distribution is adopted, so that the air distribution uniformity is improved, the air distribution structure is simplified, and the running stability of the device is improved; in addition, by applying the technical scheme of the invention, the area of air distribution at the bottom of the gasification furnace is greatly reduced, and the number of air caps is reduced, thereby reducing the cost. The graded air distribution and the moving bed slag discharge enable oxygen-containing gas to enter the gasifier through multi-point dispersion, uniform distribution of a gasifier flow field and a gasifier temperature field at high temperature in a dense-phase region at the bottom of the gasifier is guaranteed, coking caused by local high temperature in the gasifier is avoided, meanwhile, the retention time of bottom slag at the bottom of the gasifier is prolonged, the carbon content of the bottom slag can be effectively reduced, and the carbon conversion rate of a system is improved. The invention distributes wind through the wind pipe, and has small resistance, low energy consumption and low processing and installation cost. In addition, the invention can adjust the axial speed of the dense-phase region of the gasification furnace by adjusting the introduction amount of the gasification agents with different heights, realize effective separation of coarse particles and fine particles, and reduce the content of circulating semicoke in the bottom slag, thereby reducing the carbon content of the bottom slag.
Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention. The scope of applicability of the present invention is defined by the appended claims and their equivalents.
List of reference numerals:
1 gasification furnace hearth
2 cyclone separator
3 gasifying agent nozzle
4 gas distributor
Angle between alpha gasifying agent nozzle and horizontal plane
Theta cone angle
The angle between the central line of the beta gasifying agent nozzle and the tangent of the circumference of the gasification furnace.
Claims (4)
1. A circulating fluidized bed gasification method using a circulating fluidized bed gasification apparatus, the circulating fluidized bed gasification apparatus comprising: gasifier furnace (1), cyclone (2) and returning the glassware, wherein:
the lower part of the gasification furnace hearth (1) is provided with an air distribution device;
the air distribution device comprises a plurality of gasifying agent nozzles (3), at least two gasifying agent nozzles (3) in the plurality of gasifying agent nozzles (3) are arranged on different vertical heights,
the plurality of gasifying agent nozzles (3) are divided into a plurality of gasifying agent nozzle groups,
the gasifying agent spouts (3) in each gasifying agent spout group are distributed on a circle, and the extension line of the central line of the gasifying agent spout (3) in the gasifying agent spout group positioned at the uppermost layer does not pass through the center of the circle,
a conical section is arranged at the lower part of the gasification furnace hearth (1), and a plurality of gasifying agent nozzles (3) of the air distribution device are arranged on the conical section;
the circulating fluidized bed gasification method comprises the following steps:
the gasification agent airflow enters the gasification furnace through the air distribution device to form a rotational flow, wherein the gasification agent airflow entering the bottom of the gasification furnace through the gasification agent nozzle (3) in the gasification agent nozzle group on the uppermost layer forms a tangent circle, the tangent circle enables the material on the lower part of the hearth (1) of the gasification furnace to be in a rotational flow state, so that the coarse particle material is gathered to the axis area of the gasification furnace at the bottom of the gasification furnace, and the fine particle material is distributed in the relatively peripheral area and simultaneously performs gasification reaction with the gasification agent, thereby realizing the effective separation of the coarse particle material and the fine particle material.
2. The circulating fluidized bed gasification process of claim 1, wherein:
the gas velocity at the outlet of the gasifying agent nozzles is 30-70m/s, and the bed velocity between the gasifying agent nozzles with different heights is maintained to be more than 3.5 m/s.
3. The circulating fluidized bed gasification process of claim 2, wherein:
the oxygen concentration of each gasifying agent nozzle group is gradually increased from bottom to top.
4. The circulating fluidized bed gasification process of claim 3, wherein:
the gas velocity at the outlet of the gasifying agent nozzle is 35-60 m/s.
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| CN113750664B (en) * | 2021-08-31 | 2023-02-28 | 成都易态科技有限公司 | Filter and dust removal method |
| CN115029162B (en) * | 2022-08-10 | 2022-11-15 | 北京中瀚能源有限公司 | Gasification device and staged gasification method |
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| US4198210A (en) * | 1979-02-23 | 1980-04-15 | Exxon Research & Engineering Co. | Gas distributor for fluidized bed coal gasifier |
| DE3071595D1 (en) * | 1979-12-08 | 1986-06-12 | Rheinische Braunkohlenw Ag | Process for operating a fluidized bed reactor for gasifying carbonaceous material |
| CA2044074C (en) * | 1990-07-03 | 2003-01-21 | Craig Y. Sabottke | Controlling temperature, yields and selectivity in a fluid hydrocarbon conversion and cracking apparatus and process comprising a novel feed injection system |
| CN2568664Y (en) * | 2002-09-17 | 2003-08-27 | 东南大学 | Orienting jetting fluidized bed gasification furnace |
| US8110155B2 (en) * | 2003-06-20 | 2012-02-07 | Drexel University | Vortex reactor and method of using it |
| JP2008231294A (en) * | 2007-03-22 | 2008-10-02 | Electric Power Dev Co Ltd | Two-stage gasification furnace |
| CN101372635B (en) * | 2008-10-15 | 2011-07-06 | 东南大学 | High-density pressurized fluidized bed coal gasification apparatus and method |
| CN201276544Y (en) * | 2008-10-15 | 2009-07-22 | 东南大学 | Coal gasification apparatus with high carbon transformation |
| CN102120936B (en) * | 2010-01-07 | 2013-07-10 | 中国科学院过程工程研究所 | Method and device for jet/preoxidation/pyrolysis/fluidized bed gasification of carbon-containing solid fuel |
| CN203639430U (en) * | 2013-12-26 | 2014-06-11 | 中建安装工程有限公司 | Terrace type pulverized coal fluidized bed high-efficiency gasification furnace |
| MY174567A (en) * | 2013-12-30 | 2020-04-27 | Regenergy Tech Sdn Bhd | An apparatus for producing biofuels from biomass |
| CN107267219B (en) * | 2017-08-01 | 2023-05-23 | 中国科学院工程热物理研究所 | Tangential air distribution circulating fluidized bed gasification device and gasification method |
| CN107312575B (en) * | 2017-08-01 | 2023-07-18 | 中国科学院工程热物理研究所 | Circulating fluidized bed gasification device with graded air distribution and gasification method |
| CN108059978A (en) * | 2017-12-19 | 2018-05-22 | 中科合肥煤气化技术有限公司 | A kind of atmosphere circulating fluidized bed gasification furnace shortest agent system |
| CN110205164B (en) * | 2019-06-11 | 2020-11-03 | 中国科学院工程热物理研究所 | Circulating fluidized bed gasification device and circulating fluidized bed gasification method |
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| CN112745966A (en) | 2021-05-04 |
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