Anti-coking system for material returning device of biomass circulating fluidized bed gasifier

Abstract

The invention discloses an anti-coking system for a material returning device of a biomass circulating fluidized bed gasifier. The system comprises a circulating fluidized bed gasification furnace used for biomass gasification, the upper portion of the circulating fluidized bed gasification furnace is communicated with a cyclone separator, the bottom end of the cyclone separator is communicated with a return feeder, an outlet of the return feeder is communicated with the circulating fluidized bed gasification furnace, and the side edge of the cyclone separator is communicated with an inclined chute. An inlet of the inclined chute is communicated with a quantitative feeder, the upper end of the quantitative feeder is communicated with a gate valve, an inlet of the gate valve is communicated with a hopper, an inlet of the hopper is communicated with a conveyor, an inlet of the conveyor is communicated with an elevator, and a high-melting-point ash feeding port is formed in the lower portion of the elevator. The biomass ash melting point at the coking position is changed, the coking problem is fundamentally solved, steam can be sprayed into the coking position for rapid cooling, and therefore the coking phenomenon is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of gasifiers, and in particular to a material return device anti-coking system of a biomass circulating fluidized bed gasifier. Background Art

[0002] Under the background of carbon neutrality and carbon peak, wind power, solar energy, biomass energy and other renewable energy power generation industries have been vigorously developed. Biomass energy is the world's fourth largest energy source after coal, oil and natural gas, and is a clean and renewable energy source. my country is a major agricultural and forestry country with abundant biomass raw materials. Biomass gasification uses biomass as raw material, gasifies biomass into carbon monoxide and hydrogen, and then reuses it. It is an important way to utilize biomass energy.

[0003] The syngas from biomass gasification can be used as an alternative fuel for industrial boilers and kilns such as coal-fired power plants, lime kilns, cement kilns, etc. It can also be used to synthesize fuel methanol. At present, biomass gasification is developing rapidly, for example, biomass gasification is used as fuel gas to be transported to coal-fired power plants, and biomass gasification is used to synthesize methanol.

[0004] In the existing technology, the mainstream gasification technology for biomass is the circulating fluidized bed gasification technology. However, the current circulating fluidized bed gasification technology has the following technical problems: in actual operation, since biomass contains more alkali metals and the ash melting point is low, coking is prone to occur under specific working conditions, resulting in an imbalance in bed pressure, poor fluidization effect, poor operation of the gasifier, and even shutdown. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a return device anti-coking system for a biomass circulating fluidized bed gasifier, which not only changes the melting point of biomass ash at the coking position, but also can spray steam into the coking position for rapid cooling, thereby avoiding the occurrence of coking.

[0006] In order to achieve the above-mentioned purpose, the present invention is designed to provide a biomass circulating fluidized bed gasifier with a return device anti-coking system, comprising a circulating fluidized bed gasifier for biomass gasification, wherein the upper part of the circulating fluidized bed gasifier is connected to a cyclone separator, the lower end of the cyclone separator is connected to a return device, and the return device outlet is connected to the circulating fluidized bed gasifier, and the special features thereof are:

[0007] The side of the cyclone separator is connected to an inclined chute inclined upward, the inlet of the inclined chute is connected to a quantitative feeder, the upper end of the quantitative feeder is connected to a gate valve, the inlet of the gate valve is connected to a vertically arranged hopper, the inlet of the hopper is connected to a conveyor, the inlet of the conveyor is connected to an elevator, a high-melting-point ash feed port is provided at the lower part of the elevator, and the elevator can lift the high-melting-point ash to the feeding height of the cyclone separator.

[0008] Furthermore, a 1# steam nozzle for spraying steam is arranged inside the return device.

[0009] Furthermore, the 1# steam nozzle is arranged at the bottom of the return device.

[0010] Furthermore, a 2# steam nozzle is also provided at the bottom of the return device.

[0011] Furthermore, the material return device is temperature-interlocked with the 1# steam nozzle, the 2# steam nozzle, and the gate valve.

[0012] Furthermore, the conveyor is a horizontally arranged screw conveyor.

[0013] Furthermore, the elevator is a vertically arranged bucket elevator.

[0014] The advantages of the present invention are:

[0015] 1. According to the operation of the project, the present invention finds that the return feeder of the fluidized bed gasifier is a location where coking is more likely to occur. When the temperature of the return feeder increases significantly, it indicates that obvious coking has occurred in the biomass at that location;

[0016] 2. In the present invention, when the temperature of the returner is higher than the normal working condition, it indicates that there is a risk of coking in the returner. On the one hand, the gate valve is opened, and the high melting point ash enters the returner through the cyclone separator and mixes with the original low melting point biomass ash, thereby increasing the melting point of the biomass ash at the coking position, fundamentally solving the coking problem; on the other hand, steam is sprayed to the coking position of the returner, and the sprayed steam reacts with the high temperature biomass at the coking position to endothermically reduce the temperature of the returner, thereby avoiding coking of the biomass in the returner;

[0017] The anti-coking system of the return device of the biomass circulating fluidized bed gasifier of the present invention not only changes the melting point of biomass ash at the coking position to fundamentally solve the coking problem, but also can spray steam into the coking position to quickly cool it down, thereby avoiding the occurrence of coking. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention;

[0019] In the figure: circulating fluidized bed gasifier 1, cyclone separator 2, return device 2-1, elevator 3, conveyor 4, hopper 5, gate valve 6, quantitative feeder 7, inclined chute 8, 1# steam nozzle 9, 2# steam nozzle 10. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the invention.

[0021] like Figure 1 As shown, the anti-coking system of the return device of the biomass circulating fluidized bed gasifier of the present invention includes a circulating fluidized bed gasifier 1 for biomass gasification, the upper part of the circulating fluidized bed gasifier 1 is connected to a cyclone separator 2, the bottom end of the cyclone separator 2 is connected to a return device 2-1, and the outlet of the return device 2-1 is connected to the circulating fluidized bed gasifier 1.

[0022] After the biomass in the circulating fluidized bed gasifier 1 is gasified, the syngas carries part of the biomass into the cyclone separator 2. Under the action of the airflow, the syngas and the biomass are separated. The syngas enters the next process, and the biomass falls into the return device 2-1.

[0023] According to the project operation situation, the present invention finds that the returner 2-1 of the fluidized bed gasifier 1 is a location where coking is more likely to occur. When the temperature of the returner 2-1 increases significantly, it indicates that obvious coking has occurred in the biomass at this location.

[0024] The returner 2-1 is provided with a 1# steam nozzle 9 for spraying steam. When the temperature of the returner 2-1 rises, it indicates that the returner 2-1 has a risk of coking. The 1# steam nozzle 9 is opened, and after the steam enters the returner 2-1, an endothermic reaction occurs with the high-temperature biomass in the returner 2-1, which can quickly reduce the temperature of the returner 2-1, thereby preventing the biomass in the returner from coking.

[0025] Preferably, the 1# steam nozzle 9 is arranged at the bottom of the returner 2-1. The bottom of the returner 2-1 is also provided with a 2# steam nozzle 10. The steam flow ratio of the 1# steam nozzle 9 to the 2# steam nozzle 10 is 3:1.

[0026] When a small amount of coking appears on the biomass in the returner, open the 2# steam nozzle 10; when a large amount of coking appears on the biomass in the returner, open the 1# steam nozzle 9; when a large amount of coking appears on the biomass in the returner, open the 2# steam nozzle 10 and the 1# steam nozzle 9 at the same time to reduce the temperature of the returner 2-1.

[0027] The side of the cyclone separator 2 is connected with an inclined chute 8 inclined upward, the inlet of the inclined chute 8 is connected with a quantitative feeder 7, the upper end of the quantitative feeder 7 is connected with a gate valve 6, the inlet of the gate valve 6 is connected with a vertically arranged hopper 5, the inlet of the hopper 5 is connected with a conveyor 4, the inlet of the conveyor 4 is connected with an elevator 3, the lower part of the elevator 3 is provided with a high melting point ash feeding port, and the elevator 3 can lift the high melting point ash to the feeding height of the cyclone separator 2.

[0028] Normally, the melting point of the original low-melting-point ash is 700-800°C. The high-melting-point ash in this embodiment is a material with a temperature of more than 1000°C, including kaolin, olivine, quartz sand, bauxite, and the like.

[0029] The elevator 3 lifts the high melting point ash to the height of the cyclone separator 2. The outlet of the elevator 3 is connected to the conveyor 4, and the outlet of the conveyor 4 is connected to the hopper 5. The hopper 5 is connected to the gate valve 6, and then connected to the inclined chute 8, which is connected to the cyclone separator 2. When the temperature of the returner 2-1 is higher than the normal working condition, it indicates that the returner 2-1 has a coking risk. The gate valve 6 is opened, and the high melting point ash enters the returner 2-1 through the cyclone separator 2. With the help of airflow, the original low melting point ash is flushed, so that the low melting point ash falls smoothly and returns. After mixing with the low melting point ash, the ash melting point in the biomass fluidized bed gasifier can be increased, fundamentally solving the coking problem.

[0030] The returner 2-1 is temperature-interlocked with the 1# steam nozzle 9, the 2# steam nozzle 10, and the gate valve 6. When the temperature of the returner 2-1 is higher than the normal temperature, the 1# steam nozzle 9 and / or the 2# steam nozzle 10 are started, and the gate valve 6 is opened to start the system.

[0031] Preferably, the conveyor 4 is a horizontally arranged screw conveyor, and the elevator 3 is a vertically arranged bucket elevator.

[0032] The anti-coking system of the return device of the biomass circulating fluidized bed gasifier of the present invention not only changes the melting point of biomass ash at the coking position to fundamentally solve the coking problem, but also can spray steam into the coking position to quickly cool it down, thereby avoiding the occurrence of coking.

[0033] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A material return device anti-coking system for a biomass circulating fluidized bed gasifier, comprising a circulating fluidized bed gasifier (1) for biomass gasification, wherein the upper portion of the circulating fluidized bed gasifier (1) is connected to a cyclone separator (2), the lower end of the cyclone separator (2) is connected to a material return device (2-1), the outlet of the material return device (2-1) is connected to the circulating fluidized bed gasifier (1), and characterized in that: The cyclone separator (2) is connected to a slanted chute (8) inclined upward at the side, the slanted chute (8) is connected to a quantitative feeder (7) at its inlet, the quantitative feeder (7) is connected to a gate valve (6) at its upper end, the gate valve (6) is connected to a vertically arranged hopper (5) at its inlet, the hopper (5) is connected to a conveyor (4) at its inlet, the conveyor (4) is connected to an elevator (3) at its inlet, a high melting point ash feed port is provided at the lower part of the elevator (3), and the elevator (3) is capable of lifting the high melting point ash to a feeding height for the cyclone separator (2).

2. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 1, characterized in that: The return device (2-1) is provided with a #1 steam nozzle (9) for spraying steam.

3. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 2, characterized in that: The 1# steam nozzle (9) is arranged at the bottom of the return device (2-1).

4. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 3, characterized in that: A 2# steam nozzle (10) is also provided at the bottom of the return device (2-1).

5. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 4, characterized in that: The return device (2-1) is temperature-interlocked with the 1# steam nozzle (9), the 2# steam nozzle (10) and the gate valve (6).

6. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 1, characterized in that: The conveyor (4) is a horizontally arranged screw conveyor.

7. The anti-coking system of the material return device of the biomass circulating fluidized bed gasifier according to claim 6, characterized in that: The elevator (3) is a vertically arranged bucket elevator.

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