A circulating fluidized bed boiler circulating ash pyrolysis coal / biomass tar preparation device and method

Abstract

The present application relates to low rank coal / biomass low carbon clean and efficient cascade conversion technical field, especially to a circulating fluidized bed boiler circulating ash pyrolysis coal / biomass tar preparation device and method, cyclone separator and centrifugal double vortex rapid pyrolyzer coaxial arrangement, cyclone separator is equipped with multiple inlets, coaxially nested inner exhaust pipe in the top exhaust pipe, and its longitudinal through cyclone separator until the centrifugal double vortex rapid pyrolyzer inside, the material leg of cyclone separator is connected with the top plate of centrifugal double vortex rapid pyrolyzer;The centrifugal double vortex rapid pyrolyzer adopts the combined structure of cylinder and cone, the cylindrical ring plate is installed in the top of the cylinder and around the inner exhaust pipe, multiple rectangular inlets are arranged on the upper side of the cylinder, the inlet is tangent to the cylinder, the cone bottom is connected with the material leg, the present application separates combustion flue gas, extracts circulating fluidized bed boiler circulating ash, and rapidly transfers the heat carried by the circulating ash to coal / biomass, realizes the rapid pyrolysis of coal / biomass.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-rank coal / biomass low-carbon clean and efficient cascade conversion, in particular to low-rank coal / biomass pyrolysis and gasification or combustion multi-substance cascade clean conversion technology. The present application is not only suitable for catalytic pyrolysis of low-rank coal / biomass, but also suitable for hydrogenation pyrolysis and co-pyrolysis. BACKGROUND

[0002] Low-rank coal accounts for about 45% of the total coal reserves in China, and is similar to biomass in that its energy density is low, but it contains a large amount of aromatic structures and cyclic hydrocarbons in chemical composition, which is a good raw material for co-production of oil and high-value chemicals. Therefore, low-rank coal is not suitable for direct combustion in the furnace, and it is a more economical and reasonable way to extract it by pyrolysis technology. Based on this understanding, Chinese patent application CN102504842A (publication number) proposes the concept of three fluidized bed coal pyrolysis-gasification-combustion cascade utilization technology, which contains a circulating fluidized bed combustion furnace. The invention patent mainly describes the technical idea, and does not explain the specific device structure. Chinese patent CN103881761A also proposes to use circulating ash as a heat source to provide energy for coal pyrolysis and gasification. For the pyrolysis link, the invention mainly solves the problem of high dust content in the pyrolysis oil gas, and the technical solution is to use the filtering effect of the particle bed in the gasifier to remove dust. The performance characteristics of the pyrolyzer itself, whether the hot flue gas in the cyclone separator will enter the pyrolyzer, etc. are not clearly stated.

[0003] Patent CN103992824A proposes a cyclone pyrolysis furnace using high-temperature gas as a heat source. The applicant's earlier patent CN106336907A uses a similar idea to design a pyrolysis reactor, which uses both flue gas and heat-carrying particles generated by combustion as a heat source. However, the pyrolysis technical solution using flue gas as a heat source is not suitable for a system based on a circulating fluidized bed boiler, because the flue gas produced by the boiler not only has a large flow rate, but also uses excess oxygen to ensure complete combustion. On the one hand, the large flow rate of flue gas will dilute the pyrolysis oil gas, making it difficult to separate the pyrolysis oil gas later; on the other hand, the high-temperature flue gas and the oxygen environment will burn and damage the high-value components in the pyrolysis oil gas, reducing the oil yield.

[0004] The components of pyrolysis oil gas are complex, containing some high-boiling organic products. During the transportation of pyrolysis oil gas, high-boiling products are prone to stick to the wall and block the pipeline, causing unplanned shutdown and safety hazards. SUMMARY

[0005] The application aims to provide a circulating fluidized bed boiler circulating ash coal / biomass pyrolysis tar device and method, and solve the problems that high flow flue gas can dilute pyrolysis oil gas, subsequent pyrolysis oil gas separation is difficult, high temperature flue gas and oxygen environment can burn high value components in pyrolysis oil gas, reduce oil yield, and high boiling point products are easy to stick to wall surface and block pipeline.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A circulating fluidized bed boiler circulating ash coal / biomass pyrolysis tar device, comprising a cyclone separator and a centrifugal double vortex rapid pyrolysis device, wherein the cyclone separator and the centrifugal double vortex rapid pyrolysis device are arranged coaxially and vertically, the cyclone separator is provided with multiple inlets, an exhaust pipe is arranged at the top center, an inner exhaust pipe is coaxially nested in the exhaust pipe and longitudinally penetrates the cyclone separator to the inside of the centrifugal double vortex rapid pyrolysis device, a material leg is connected to the bottom end of the cyclone separator, the material leg and the inner exhaust pipe form an annular gap as a discharge pipe, a conical blocking piece is installed at the bottom end of the inner exhaust pipe, the conical blocking piece is coaxial with the inner exhaust pipe, and a bottom plate is arranged at the bottom end of the conical blocking piece to form a closed structure with the pipe wall of the inner exhaust pipe, and the material leg of the cyclone separator is connected to the top plate of the centrifugal double vortex rapid pyrolysis device.

[0008] The centrifugal double vortex rapid pyrolysis device adopts a combination structure of a cylinder and a cone, multiple circumferentially distributed rectangular inlets are arranged on the upper side of the cylinder, and different pyrolysis raw materials enter the inlets respectively, the inlets are tangent to the cylinder to promote the rotation of the carrier gas and particles, and the carrier gas forms a quasi-Langmuir vortex turbulent field after rotation to realize rapid heat transfer between gas and solid, a material leg is connected to the bottom of the cone, the material leg is a discharge structure, and solid pyrolysis semi-coke and circulating ash are discharged; a conical blocking piece is installed at the joint between the material leg and the bottom of the cone to stabilize the Langmuir vortex field and maintain the stability of the heat transfer performance of the pyrolysis device when the operating conditions fluctuate.

[0009] A cylindrical ring plate is installed at the top inside of the cylinder and around the inner exhaust pipe, the cylindrical ring plate is coaxial with the inner exhaust pipe, the cylindrical ring plate and the conical surface of the conical blocking piece form a semi-closed structure, gas cannot pass through, and particles can pass through under the action of gravity, the bottom plate of the cylindrical ring plate, the centrifugal double vortex rapid pyrolysis device, the cylindrical ring plate and the conical blocking plate form a circulating ash buffer space.

[0010] The position of the bottom end of the cylindrical ring plate is higher than the position of the bottom plate of the conical blocking piece.

[0011] A circulating ash coal / biomass pyrolysis tar method, and the steps are as follows:

[0012] S1: high temperature flue gas and circulating ash enter the cyclone separator together, and after separation, the circulating ash is introduced into the centrifugal double vortex rapid pyrolysis device through the material leg;

[0013] S2: the carrier gas transports the coal and / or biomass from different tangential inlets into the centrifugal double-vortex fast pyrolysis reactor respectively and rotates in the reactor, in the process of which the coal and / or biomass are rapidly heated, the temperature rising rate reaching 500 K·s -1 The above, and a fast pyrolysis reaction occurs;

[0014] S3: the pyrolysis oil gas flows out from the inner exhaust pipe and enters the subsequent tar recovery and processing device under the heat preservation effect of the high-temperature flue gas in the cyclone separator;

[0015] S4: the pyrolysis semi-coke enters the leg with the circulating ash and flows back into the circulating fluidized bed boiler.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] (1) The cyclone separator is provided with multiple inlets for separating the flue gas and the circulating ash, and the multiple inlets are symmetrically distributed to uniformly distribute the ash particles on the inner surface of the cyclone separator and then uniformly stack them in the annular gap; the inner exhaust pipe longitudinally penetrating the cyclone separator stabilizes the rotating center of the gas flow and prevents the eccentric swing of the rotating center and the destruction of the stability of the ash stacking layer;

[0018] (2) During the operation of the circulating fluidized bed boiler, the amount of the flue gas and the circulating ash entering the cyclone separator often fluctuates, and the circular baffle, the conical baffle and the top of the centrifugal double-vortex fast pyrolysis reactor constitute the circulating ash transmission and buffering components, so that the amount of the circulating ash entering the fast pyrolysis reactor is stable, and the buffering structure also realizes gas sealing to prevent the mutual jump of the gas in the fast pyrolysis reactor and the cyclone separator;

[0019] (3) The centrifugal double-vortex fast pyrolysis reactor adopts a combination structure of a cylinder and a cone, the inlet is tangent to the cylinder, which promotes the rotation of the carrier gas and the particles, and the following two principles are used to realize rapid heating: one is that the rotating carrier gas forms a quasi-Langmuir vortex turbulent field to realize strong gas-solid convective heat transfer, the heat is quickly transferred from the high-temperature circulating ash to the gas, and the gas is quickly heated; the other is that the cold and hot particles are closely gathered on the edge wall under the action of centrifugal force, and the sufficient contact between the two is conducive to rapid heat transfer. Under the action of the above two mechanisms, the temperature rising rate of the pyrolysis raw material reaches 100 K / s (key core advantage), and fast pyrolysis is realized; the conical baffle installed at the lower part of the cone stabilizes the Langmuir vortex field under the fluctuation of the operating conditions, and maintains the stability of the heat transfer performance of the pyrolysis reactor; under the action of the quasi-Langmuir vortex field, the pyrolysis oil gas enters the inner exhaust pipe, and the pyrolysis semi-coke descends into the leg, and the pyrolysis oil gas and the semi-coke realize production and separation in the reactor, thereby improving the integration degree of the device;

[0020] (4) The temperature in the cyclone separator is relatively high, and the inner exhaust pipe prevents the adhesion of high-boiling-point organic products on the wall surface, which helps to improve the recovery rate;

[0021] (5) The present application is directed to the characteristics of a circulating fluidized bed boiler, separates combustion flue gas, extracts circulating ash of the circulating fluidized bed boiler, and rapidly transfers the heat carried by the circulating ash to coal / biomass to achieve rapid pyrolysis of coal / biomass. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a structural schematic diagram of the present application;

[0023] In the figure: 1, cyclone separator; 2, centrifugal double-vortex rapid pyrolyzer; 3, inner exhaust pipe; 4, exhaust pipe; 5, first leg; 6, discharge pipe; 7, conical stopper; 8, cylindrical ring plate; 9, inlet; 10, second leg; 11, conical stop block. EMBODIMENT

[0024] The technical solutions of the present application will be further described below in combination with the drawings and examples.

[0025] As shown in Figure 1 A circulating fluidized bed boiler circulating ash pyrolysis coal / biomass tar device, comprising a cyclone separator 1 and a centrifugal double-vortex rapid pyrolyzer 2, the cyclone separator 1 and the centrifugal double-vortex rapid pyrolyzer 2 are arranged coaxially and vertically, the cyclone separator 1 is provided with multiple inlets, the top center is provided with an exhaust pipe 4, the exhaust pipe 4 is coaxially nested with an inner exhaust pipe 3, the inner exhaust pipe 3 penetrates the cyclone separator 1 and extends into the centrifugal double-vortex rapid pyrolyzer 2, the bottom end of the cyclone separator 1 is connected with a first leg 5, the first leg 5 and the inner exhaust pipe 3 form an annular gap as a discharge pipe 6, the bottom end of the inner exhaust pipe 3 is installed with a conical stopper 7, the conical stopper 7 is coaxial with the inner exhaust pipe 3, and the bottom end of the conical stopper 7 is provided with a bottom plate, which forms a closed structure with the inner exhaust pipe 4 wall; the first leg 5 is connected with the top plate of the centrifugal double-vortex rapid pyrolyzer 2; the first leg of the cyclone separator is connected with the top plate of the centrifugal double-vortex rapid pyrolyzer, guiding the circulating ash to fall at a flow rate of 1 kg / s, and the falling particles form a particle seal to block 96.7% of the hot flue gas in the separator; the inner exhaust pipe prevents the adhesion of high-boiling-point organic products on the wall surface, improving the recovery rate;

[0026] The centrifugal double-vortex rapid pyrolyzer 2 adopts a combination structure of a cylinder and a cone. A cylindrical ring plate 8 is mounted at the top inside the cylinder and around an inner exhaust pipe 3. The cylindrical ring plate 8 is coaxial with the inner exhaust pipe 3, and the cylindrical ring plate 8 and the conical surface of a conical blocking piece 7 form a semi-closed structure. Gases cannot pass through, but particles can pass through under the action of gravity. The position of the bottom plate of the cylindrical ring plate 8 is higher than the position of the bottom plate of the conical blocking piece 7. The centrifugal double-vortex rapid pyrolyzer 2, the cylindrical ring plate 8 and the conical blocking piece 7 form a circulating ash transmission and buffering component. The amount of circulating ash entering the rapid pyrolyzer is stable, and gas sealing is also achieved, preventing gas from jumping between the rapid pyrolyzer and the cyclone separator. A plurality of circumferentially distributed rectangular inlets 9 are arranged on the upper side of the cylinder. Different pyrolysis raw materials enter the inlets 9, which are tangent to the cylinder and distributed at 180°. The bottom of the cone is connected to a second leg 10, and a conical blocking piece 11 is mounted at the joint between the second leg 10 and the bottom of the cone, which promotes the rotation of the carrier gas and particles, stabilizes the Rankine vortex field when the operating conditions fluctuate, and maintains the stability of the heat transfer performance of the pyrolyzer. Under the action of the quasi-Rankine vortex field, pyrolysis oil gas enters the inner exhaust pipe, and pyrolysis semi-coke descends into the second leg. Pyrolysis oil gas and semi-coke realize immediate production and separation in the reactor, and the integration of the device is improved. Embodiment

[0027] A method for pyrolyzing coal and biomass to produce tar by circulating ash, comprising the following steps:

[0028] S1: 50m 3 / h of high-temperature flue gas carrying 400 kg / h of circulating ash enters a cyclone separator together. After separation, the circulating ash is introduced into a rapid pyrolyzer through a leg;

[0029] S2: The carrier gas transports coal and / or biomass into the rapid pyrolyzer from different tangential inlets and rotates and flows therein. The coal and / or biomass are rapidly heated during the flow process, and the heating rate reaches 500 K·s -1 , and reaches the pyrolysis temperature after about 2 seconds, and a rapid pyrolysis reaction occurs;

[0030] S3: Pyrolysis oil gas flows out from the inner exhaust pipe. The coal tar yield is 8%-109&, the biomass oil yield is 40%, and the tar yield is increased by about 10% compared with the Gejin dry distillation process. Under the heat preservation effect of the high-temperature flue gas in the cyclone separator, the pyrolysis oil gas enters the subsequent tar recovery and processing device.

[0031] S4: Pyrolysis semi-coke enters the leg with the circulating ash, and 99% of the particles flow into a circulating fluidized bed boiler.

[0032] Comparative Example 1

[0033] A pyrolysis reactor similar to the present invention is proposed in Chinese patent CN104789245A, which also uses granular heat carriers to pyrolyze coal and / or biomass. The flow field characteristics of this reactor are that the granular heat carriers are in co-current downward flow with the carrier gas in a vertically placed reactor, and the heat carriers are in free-fall state. Since the granular heat carriers are relatively dispersed and have limited contact with each other, and the gas turbulence is relatively low, the convective heat transfer rate is limited. Overall, the heating rate cannot reach fast (100~10 6 K·s -1 ), and can only reach medium speed (5~100 K·s -1 ), and the yield of the obtained tar-like substances is comparable to that of the Gejin dry distillation process.

[0034] Principle: The semi-coke / fuel is burned in the boiler to produce high-temperature circulating ash, and the high-temperature ash and high-temperature flue gas enter the cyclone separator together. The gas-solid separation ability of the cyclone separator is used to separate the high-temperature ash from the waste gas. The waste gas is collected and treated through the outer exhaust pipe 4, and the high-temperature ash enters the centrifugal double-vortex rapid pyrolysis reactor through the annular gap 6 formed by the cyclone separator leg and the inner exhaust pipe. The coal / biomass enters the centrifugal double-vortex rapid pyrolysis reactor from the inlet 9 of the vortex rapid pyrolysis reactor. Through the flow field mechanism in the rapid pyrolysis reactor, the coal / biomass is heated at a rate of 500 K / s to 600°C, and rapid pyrolysis reaction occurs to produce pyrolysis oil gas and semi-coke. The semi-coke and high-temperature circulating ash descend and enter the boiler furnace through the return valve. The pyrolysis gas can be collected through the inner exhaust pipe of the centrifugal double-vortex rapid pyrolysis reactor.

Claims

1. A circulating fluidized bed boiler circulating ash pyrolysis coal and / or biomass tar making device, comprising a cyclone separator (1) and a centrifugal double vortex rapid pyrolyzer (2), characterized in that, The cyclone separator (1) and the centrifugal double vortex rapid pyrolyzer (2) are arranged coaxially and vertically, the cyclone separator (1) is provided with multiple inlets which are symmetrically distributed, a gas discharge pipe (4) is arranged at the top center, an inner gas discharge pipe (3) is coaxially nested in the gas discharge pipe (4), and the inner gas discharge pipe (3) longitudinally penetrates the cyclone separator (1) and reaches the inside of the centrifugal double vortex rapid pyrolyzer (2), a first material leg (5) is connected to the bottom end of the cyclone separator (1), the first material leg (5) and the inner gas discharge pipe (3) form an annular gap as a material discharge pipe (6), a conical blocking piece (7) is mounted at the bottom end of the inner gas discharge pipe (3), the conical blocking piece (7) is coaxial with the inner gas discharge pipe (3), and a bottom plate is arranged at the bottom end of the conical blocking piece (7), the bottom plate and the pipe wall of the inner gas discharge pipe (3) form a closed structure, and the first material leg (5) is connected to the top plate of the centrifugal double vortex rapid pyrolyzer (2); The centrifugal double vortex rapid pyrolyzer (2) adopts a combination structure of a cylinder and a cone, multiple circumferentially distributed rectangular inlets (9) are arranged on the upper side of the cylinder, the rectangular inlets (9) are tangent to the cylinder, so as to make the carrier gas and particles rotate, a second material leg (10) is connected to the bottom of the cone, the second material leg (10) is a material discharge structure, and solid pyrolysis semi-coke and circulating ash are discharged; a conical blocking piece (11) is mounted at the joint between the second material leg (10) and the bottom of the cone, high-temperature flue gas generated by combustion of the circulating fluidized bed boiler and high-temperature circulating ash enter the cyclone separator (1) together; A cylindrical ring plate (8) is mounted at the top inside of the cylinder and around the inner gas discharge pipe (3), the cylindrical ring plate (8) is coaxial with the inner gas discharge pipe (3), the cylindrical ring plate (8) and the conical surface of the conical blocking piece (7) form a semi-closed structure, and the centrifugal double vortex rapid pyrolyzer (2), the cylindrical ring plate (8) and the conical blocking piece (7) form a circulating ash buffer space.

2. The circulating fluidized bed boiler circulating ash pyrolysis coal and / or biomass tar making device according to claim 1, characterized in that, The position of the bottom end of the cylindrical ring plate (8) is higher than the position of the bottom plate of the conical blocking piece (7).

3. A method of coal and / or biomass to tar pyrolysis in a circulating ash based on the apparatus of claim 2, characterized in that, The steps are as follows: S1: high-temperature flue gas and circulating ash enter the cyclone separator (1) together, and after separation, the circulating ash is introduced into the centrifugal double vortex rapid pyrolyzer (2) through the first material leg (5); S2: the carrier gas transports the coal and / or biomass from different rectangular inlets (9) into the centrifugal double-vortex rapid pyrolysis reactor (2) respectively, and rotates in the reactor, in the process of which the coal and / or biomass are rapidly heated, and the heating rate reaches 500 K·s -1 The above, and rapid pyrolysis reactions occur; S3: pyrolysis oil gas flows out from the inner gas discharge pipe (3) and enters a subsequent tar recovery and processing device under the heat preservation effect of the high-temperature flue gas in the cyclone separator (1); S4: pyrolysis semi-coke enters the second material leg (10) with the circulating ash and flows back into the circulating fluidized bed boiler.

Images