CN108264937B

CN108264937B - Double fluidized bed reaction system

Info

Publication number: CN108264937B
Application number: CN201711391427.9A
Authority: CN
Inventors: 严林博; 曹旸; 何伯述; 李学政
Original assignee: Beijing Jiaotong University
Current assignee: Beijing Jiaotong University
Priority date: 2017-12-21
Filing date: 2017-12-21
Publication date: 2020-09-04
Anticipated expiration: 2037-12-21
Also published as: CN108264937A

Abstract

The invention discloses a double fluidized bed reaction system, which comprises a gasification furnace, a combustion furnace, a first pipeline and a second pipeline, wherein the first pipeline and the second pipeline are communicated with the gasification furnace; the first tube includes a first manifold and a second manifold, one of the first and second manifolds being configured as an evaporator tube containing a steam generator. The double fluidized bed reaction system provided by the invention can realize the self-supply of the steam of the double fluidized bed gasification furnace, and can change the output of the evaporator by changing the bed material amount entering the evaporation pipeline, thereby flexibly controlling the steam yield. The invention can reduce or even avoid the use of an external steam generation system, thereby leading the whole gasifier to be more compact, improving the operating economy of the gasifier and reducing the operating cost of the gasifier.

Description

Double fluidized bed reaction system

Technical Field

The present invention relates to the field of reactors. And more particularly to a dual fluidized bed reaction system.

Background

The gasification technology can realize clean and efficient utilization of solid fuels such as coal, biomass and the like, wherein the steam fluidized bed gasification can be widely concerned and researched by the industry because the steam fluidized bed gasification can be efficiently operated under normal pressure. Since the steam gasification process is endothermic, additional heat is required to maintain the gasification process continuous, and this heat is typically supplied by burning a portion of the fuel in the industry. For a single gasifier, if air combustion is used for heat supply, a large amount of N in the air₂Can dilute the concentration of combustible components in the fuel gas and reduce the quality of the fuel gas. If oxygen-rich combustion gasification is used, additional energy is consumed to produce additional oxygen, thereby reducing the efficiency of the gasifier.

In the prior art, the problems are generally solved by adopting a double fluidized bed gasification technology, but the cost of the current gasification technology is relatively high, and particularly, the cost of the current double fluidized bed gasification technology is relatively high when the current double fluidized bed gasification technology is applied to low-quality energy sources such as biomass. Meanwhile, most of biomass energy sources and the like need steam as a gasifying agent, and energy consumption is needed when steam is generated, and if the heat of the double fluidized bed gasification furnace is used for realizing steam supply, the extra energy consumption of the gasification furnace can be reduced.

Therefore, it is necessary to modify the current dual fluidized bed gasification technology appropriately to provide a dual fluidized bed reaction system.

Disclosure of Invention

An object of the present invention is to provide a dual fluidized bed reaction system to solve the problems that the cost of the current dual fluidized bed gasification technology is too high and it is difficult to control the steam generation amount when realizing the self-supply of the steam.

In order to achieve the purpose, the invention adopts the following technical scheme:

a double fluidized bed reaction system comprises a gasification furnace, a combustion furnace, a first pipeline and a second pipeline, wherein the first pipeline and the second pipeline are communicated with the gasification furnace; the first pipeline comprises a first branch and a second branch, one of the first branch and the second branch is provided with an evaporation pipeline provided with a steam generator, and the steam generator is used for heating water added into the evaporation pipeline into steam and transmitting the steam to the gasification furnace through the steam pipeline.

Preferably, the steam generator is a spiral tube heat exchanger, and the spiral tube heat exchanger is arranged on the outer side wall of the evaporation pipeline.

Preferably, an auxiliary evaporator is arranged at the upstream position of the evaporation pipeline and used for accelerating the evaporation of water in the bed material.

Preferably, a flow distribution plate is arranged at the junction of the first branch pipe and the second branch pipe, and the flow distribution plate controls the flow of the bed material of the evaporation pipeline.

Preferably, the gasification furnace is a bubbling bed gasification furnace.

Preferably, the furnace is a riser furnace.

Preferably, the bed material of the gasification furnace and the combustion furnace is quartz sand.

The invention has the following beneficial effects:

the invention provides a double fluidized bed reaction system, which can realize the self-supply of steam of a double fluidized bed gasification furnace and can change the output of an evaporator by changing the bed material amount entering an evaporation pipeline so as to flexibly control the steam yield. The invention can reduce or even avoid the use of an external steam generation system, thereby leading the whole gasifier to be more compact, improving the operating economy of the gasifier and reducing the operating cost of the gasifier.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic flow diagram of a dual fluidized bed reaction system according to the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

Fig. 1 is a schematic flow chart of a dual fluidized bed reaction system provided by the present invention, which includes a gasification furnace 1, a combustion furnace 2, and a first pipeline and a second pipeline 32 communicating the gasification furnace 1, wherein the gasification furnace 1 and the combustion furnace 2 are filled with bed materials, the first pipeline transports the bed materials from the combustion furnace 2 to the gasification furnace 1, and the second pipeline 32 transports the bed materials from the gasification furnace 1 to the combustion furnace 2; the first pipe includes a first branch and a second branch, one of which is provided as an evaporation pipe 31 equipped with a steam generator for heating water added to the evaporation pipe 31 into steam and delivering the steam to the gasification furnace 1 through the steam pipe. The water in the bed material is added into the bed material in a counter-current manner from the downstream position of the evaporation pipeline 31, and is carried into the gasification furnace 1 from the bed material through the evaporation pipeline 31. Optionally, the gasification furnace 1 is a bubbling bed gasification furnace 1, and the combustion furnace 2 is a riser combustion furnace 2.

The invention provides a double fluidized bed reaction system, which can realize the self-supply of water vapor of a double fluidized bed gasification furnace 1, and can change the output of an evaporator by changing the bed material amount entering an evaporation pipeline 31, thereby flexibly controlling the steam yield. The invention can reduce or even avoid the use of an external steam generation system, thereby enabling the gasifier 1 to be more compact as a whole, improving the operating economy of the gasifier 1 and reducing the operating cost of the gasifier 1.

Optionally, the bed materials of the gasification furnace 1 and the combustion furnace 2 are quartz sand.

The quartz sand has good heat resistance, stable reaction and rapid heat absorption and can be used as an ideal bed material.

As a preferred technical solution, the steam generator is a spiral tube heat exchanger, and the spiral tube heat exchanger is disposed on the outer side wall of the evaporation pipeline 31.

Compared with other types of heat exchangers, the spiral tube heat exchanger has the advantages of high heating speed and high heat exchange efficiency, can be closely attached to a pipeline, reduces heat exchange loss and improves heat transfer efficiency.

Of course, in order to avoid insufficient heat supply from the single heat exchanger or failure in the reaction process, sufficient heat cannot be supplied, and therefore an auxiliary evaporator for accelerating the evaporation of water in the bed material is provided at a position upstream of the evaporation line 31.

When the heat exchanger supplies insufficient heat, the auxiliary evaporator is started and supplies heat to the bed material, it should be noted that the power of the auxiliary evaporator is generally set to be smaller than that of the spiral tube heat exchanger, but the invention is not necessarily limited, and in addition, the number of the auxiliary evaporators can be 1 or 2 or more, and those skilled in the art understand that the above arrangement can be adaptively adjusted according to actual conditions, and the invention is not limited thereto.

Preferably, a flow dividing plate 33 is arranged at the junction of the first branch pipe and the second branch pipe, and the flow dividing plate 33 controls the flow rate of the bed material of the evaporation pipeline 31.

In the preferred embodiment, the dividing plate 33 can control the bed material flow rate of the first and second branches by rotating to increase or decrease the bed material inlet area of the first and second branches, and in the above-described embodiment of the present invention, the evaporation pipe 31 can provide heat to evaporate water in the bed material into steam, thus. The content of water evaporated into steam can be controlled by the simple splitter plate 33, thereby flexibly controlling the steam yield.

The invention takes a specific experiment as an example, the bed material can be quartz sand, in a specific experiment, the weight of the bed layer in the bubbling bed gasification furnace 1 is 55kg, the diameter of the bubbling bed is about 0.3m, the height of the bed layer is about 1m, and the height of the whole bubbling bed gasification furnace 1 is about 2.5 m. The riser has a diameter of about 0.9m and a height of about 3 m. The circulation flux of the riser was 50kg/m²And s. And (2) feeding 10kg/h of bituminous coal into a bubbling bed gasification furnace 1 of the double fluidized beds through a screw feeder to undergo water evaporation, pyrolysis and coke gasification, wherein the mass ratio of water to coal is 1: 1, the initial bed preheating temperature is 800. 10kg/h of cold water flows in from the lower end of the spiral tube heater, is converted into steam through reverse heat exchange with the circulating bed material in the evaporation pipeline 31, and then enters the air chamber of the bubbling bed gasification furnace 1 to be used as fluidized air and gasification agent of the fluidized bed gasification furnace 1. Through calculation, the mixing temperature of 25 ℃ cold water at the flow rate of 10kg/h after being evaporated by an evaporator and mixed with circulating bed materials can reach about 900 ℃, and the heat absorption requirement of the bubbling bed gasification furnace 1 and the supply of a gasification agent can be completely met.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims

1. A double fluidized bed reaction system is characterized by comprising a gasification furnace, a combustion furnace, a first pipeline and a second pipeline, wherein the first pipeline and the second pipeline are communicated with the gasification furnace;

the first pipeline comprises a first branch and a second branch, one of the first branch and the second branch is provided with an evaporation pipeline provided with a steam generator, and the steam generator is used for heating water added into the evaporation pipeline into steam and transmitting the steam to the gasification furnace through the steam pipeline;

the steam generator is a spiral tube heat exchanger, and a spiral tube heat exchanger disc is arranged on the outer side wall of the evaporation pipeline.

2. The system of claim 1, wherein an auxiliary evaporator is disposed upstream of the evaporation line.

3. The system of claim 1, wherein a manifold is disposed at the intersection of said first manifold and said second manifold, said manifold controlling the flow of bed material from said evaporator circuit.

4. The system of claim 1, wherein the gasifier is a bubbling bed gasifier.

5. The system of claim 1, wherein the furnace is a riser furnace.

6. The system as claimed in claim 1, wherein the bed material of the gasification furnace and the combustion furnace is quartz sand.