CN105861069A - Solid fuel double-fluidized bed partial gasification classified converting device and method - Google Patents

Abstract

The invention relates to the technology of preparing synthesis gas from solid fuel, and aims to provide a dual-fluidized-bed partial gasification and graded conversion device and method for solid fuel. The device consists of a normal pressure or pressurized fluidized bed gasifier and a fluidized bed combustion furnace, and the pressure is 0.1‑5MPa during pressurized operation. This method uses oxygen, water vapor or carbon dioxide as a gasification agent, first gasifies solid fuel in a fluidized bed gasification furnace to generate synthesis gas, and then sends the semi-coke produced by gasification to the fluidized bed combustion furnace burn in. The invention adopts double fluidized beds to simultaneously generate synthesis gas and high-temperature flue gas, and realizes graded conversion of solid fuel; has stronger fuel adaptability, low pollutant discharge, simple operation, large processing capacity, and easy realization of large-scale production. The generated syngas has less tar content and higher calorific value. Compared with the complete gasification technology, the high carbon conversion rate is not emphasized, and the required oxygen consumption is significantly reduced. At the same time, it can reduce the reaction, reduce the cost of equipment, and have greater economic advantages.

Description

Solid fuel dual fluidized bed partial gasification fractional conversion device and method

technical field

The invention relates to the technology of preparing synthesis gas from solid fuel, in particular to a dual fluidized bed partial gasification and graded conversion device and method for solid fuel.

Background technique

my country's energy structure is coal-rich, oil-poor, and gas-deficient. my country is rich in coal resources and has a huge output. Coal accounts for 70% of my country's total energy consumption. However, the direct combustion of coal causes serious environmental pollution, which has a great impact on the sustainable development of the country's economy and people's lives. In addition, as one of the clean and renewable energy sources, biomass resources are also abundant in my country. Therefore, using relatively abundant solid fuels such as coal and biomass for power generation and synthesis gas production using relatively clean coal gasification technology can reduce environmental pollution and at the same time ease the pressure on my country's natural gas imports, so it has an important reality significance.

However, the existing gasification technology basically adopts the complete gasification method, which needs to achieve extremely high carbon conversion rate under the condition of high temperature and high pressure. The harsh reaction conditions greatly increase the manufacturing cost and maintenance cost of the reaction equipment. At the same time, the complete gasification technology consumes a lot of oxygen and needs to be equipped with a large-scale air separation unit, which greatly increases the construction cost.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a solid fuel double fluidized bed partial gasification staged conversion device and method.

For solving technical problem, solution of the present invention is:

Provide a solid fuel double fluidized bed partial gasification graded conversion device, including a fluidized bed combustion furnace and a fluidized bed gasification furnace;

The bottom of the fluidized bed gasification furnace is provided with a gasification agent inlet, the middle and lower part is provided with a solid fuel feeding port, the middle part is provided with an overflow port, and the top is provided with a synthesis gas outlet; the bottom of the fluidized bed combustion furnace is provided with an air inlet, A semi-coke material inlet is provided at the middle and lower part, and a flue gas outlet is provided at the top; the overflow port is connected to the semi-coke material inlet through a pipeline through the fourth return device;

On the synthesis gas discharge pipeline connected to the synthesis gas outlet, there is a first cyclone separator; the bottom of the first cyclone separator is connected to the semi-coke material inlet through the first feeder, or connected to the fluidized bed The inlet of circulating material in the middle and lower part of the gasifier;

A second cyclone separator is arranged on the pipeline connected with the flue gas outlet; the bottom of the second cyclone separator is connected to the semi-coke material inlet through the second feeder.

In the present invention, it also includes a third cyclone separator arranged on the synthesis gas discharge pipeline at the top outlet of the first cyclone separator; the top of the third cyclone separator is connected to the synthesis gas discharge pipeline, and its bottom is connected to the first feeder The outlet pipeline, or connected to the semi-coke material inlet through the third return device.

In the present invention, the interior of the fluidized bed gasifier is divided into an air chamber, a dense-phase area and a dilute-phase area from bottom to top; wherein, the gasification agent inlet is connected with the air chamber, and the solid fuel feeding port is located in the dense-phase area In the middle part, the overflow port is located at the top of the dense-phase area, and the synthesis gas outlet is located at the top of the dilute-phase area; the inside of the fluidized bed combustion furnace is divided into an air chamber, a dense-phase area and a dilute-phase area from bottom to top; wherein, the air inlet and The air chamber is connected, the semi-coke material inlet is located in the middle of the dense phase area, and the flue gas outlet is located at the top of the dilute phase area.

The present invention further provides a solid fuel double fluidized bed partial gasification staged conversion method based on the aforementioned device, comprising:

(1) Add coal powder and/or biomass dry powder to the fluidized bed gasification furnace through the solid fuel feed port, and mix with the gasification agent from the bottom in the dense phase zone and undergo a gasification reaction to generate synthesis gas;

Control the mass ratio of solid fuel and gasification agent to partially gasify the solid fuel; the gasification agent is a water vapor-oxygen mixture or a carbon dioxide-oxygen mixture; the fluidized bed gasifier operates under normal pressure or under pressure, and under pressure The hourly pressure is 0.1-5MPa, the operating temperature is 900-1000°C; in the gasification agent, the mass ratio of water vapor to solid fuel is 0.1-0.5, the mass ratio of oxygen to solid fuel is 0.3-1, and the mass ratio of carbon dioxide to solid fuel The mass ratio is 0.2-0.8;

(2) The synthetic gas discharged from the fluidized bed gasifier is dedusted by a one-stage or two-stage cyclone separator, and then sent to the discharge pipeline; the separated dust is sent to the semi-coke material inlet of the fluidized bed combustion furnace by the return feeder , or sent back to the dense-phase zone of the fluidized bed gasifier for re-reaction;

(3) The semi-coke material obtained from the gasification reaction is discharged from the overflow port at the top of the dense-phase zone of the fluidized bed gasifier, and sent to the semi-coke material inlet of the fluidized bed combustion furnace by the return device; it is burned in the fluidized bed In the dense-phase area of the furnace, the semi-coke material reacts with the air from the bottom to generate high-temperature flue gas at a temperature of 900-950 °C;

Control the mass ratio of the air at the bottom and the material at the entrance of the semi-coke material to 1-1.2, so that the semi-coke material can be completely combusted; the fluidized bed combustion furnace is operated under normal pressure or pressurization, and the pressure is 0.1-5MPa during pressurized operation; The temperature is 900-950°C;

(4) The flue gas discharged from the fluidized bed combustion furnace is dedusted by the cyclone separator and then sent to the discharge pipeline, and the separated dust is sent back to the semi-coke material inlet of the fluidized bed combustion furnace by the return device, and the combustion reaction is carried out again .

In the present invention, the biomass dry powder refers to the dry powder of crop stalks, the particle size of which is less than 10 mm; the particle size of the coal powder is less than 8 mm.

Description of invention principle:

Combining the chemical structure characteristics of solid fuels such as coal and biomass, the present invention first converts the part with better activity and easy gasification into synthesis gas, and then burns the produced semi-coke which is not easy to gasify as raw material to produce high-temperature smoke The gas is used in subsequent processes to produce high-temperature steam for power generation, thereby realizing partial gasification and staged conversion of solid fuels such as coal and biomass. Compared with the current complete gasification or direct combustion, the solid fuel partial gasification technology has the advantages of low oxygen consumption and low equipment cost. The synthesis gas obtained by this method can not only be used for gas turbine power generation, but also can be used as a raw material for chemical synthesis production.

Compared with the prior art, the present invention has the beneficial effects:

1. The double fluidized bed operation method combining fluidized bed gasification furnace and fluidized bed combustion furnace is adopted to generate synthesis gas and high temperature flue gas at the same time, realizing the staged conversion of solid fuel.

2. The fluidized bed gasifier and combustion furnace are used as reactors, which have stronger fuel adaptability, low pollutant emissions, simple operation, large processing capacity, and easy realization of large-scale production.

3. The fluidized bed gasifier is used for the gasification reaction of solid fuel and oxygen/water vapor or water vapor/carbon dioxide, and the generated syngas has less tar content and higher calorific value, which can be used as industrial or civil fuel; semi-coke The materials are burned in the fluidized bed combustion furnace to form high-temperature flue gas, which can be used to produce high-temperature and high-pressure steam for power generation.

4. The fluidized bed partial gasification technology is used to process solid fuels. Compared with the complete gasification technology, it does not emphasize the high carbon conversion rate, and the required oxygen consumption is significantly reduced. At the same time, it can reduce the reaction and reduce the equipment cost. It is economical sex has a greater advantage.

Description of drawings

Fig. 1 is a schematic diagram of the first implementation of the device of the present invention.

Fig. 2 is a schematic diagram of another implementation of the device of the present invention (a return device is added to the device in Fig. 1).

In the figure: solid fuel feed port 1, gasification agent inlet 2, fluidized bed gasifier 3, first feeder 4, first cyclone separator 5, third cyclone separator 6, synthesis gas discharge pipeline 7. Second cyclone separator 8, second feeder 9, fluidized bed combustion furnace 10, air inlet 11, flue gas discharge pipeline 12, overflow port 13, third feeder 14, semi-coke material inlet 15, the recycle material inlet 16, the fourth feeder 17.

detailed description

The implementation of the present invention will be described below in conjunction with the accompanying drawings.

The solid fuel double fluidized bed partial gasification staged conversion device of the present invention includes a fluidized bed combustion furnace 10 and a fluidized bed gasification furnace 3 . The bottom of the fluidized bed gasifier 3 is provided with a gasification agent inlet 2, the middle and lower part is provided with a solid fuel feed port 1, the middle part is provided with an overflow port 13, and the top is provided with a synthesis gas outlet. The bottom of the fluidized bed combustion furnace 10 is provided with an air inlet 11, the middle and lower part is provided with a semi-coke material inlet 15, and the top is provided with a flue gas outlet; the overflow port 13 is connected to the semi-coke material inlet through the fourth feeder 14 through a pipeline 15.

On the synthesis gas discharge pipeline connected with the synthesis gas outlet, a first cyclone separator 5 is provided; the bottom of the first cyclone separator 5 is connected to the semi-coke material inlet 15 through the first return device 4 (as shown in Fig. 1 shown), or connected to the circulating material inlet 16 (as shown in Figure 2) located at the lower part of the fluidized bed gasifier 3;

A second cyclone separator 8 is provided on the pipeline connected to the flue gas outlet; the bottom of the second cyclone separator 8 is connected to the semi-coke material inlet 15 through the second feeder 9, and the top is connected to the flue gas discharge pipeline 12 .

In order to further separate the dust, a third cyclone separator 6 may also be arranged on the synthesis gas discharge pipeline at the outlet of the top of the first cyclone separator 5 . The top of the third cyclone separator 6 is connected to the synthesis gas discharge pipeline 7, and its bottom is connected to the pipeline at the outlet of the first return device 4, and the collected dust is sent to the semi-coke material inlet 15 (as shown in Figure 1) , or sent to the recycle material inlet 16. Under the situation that the first return feeder 4 is connected to the circulating material inlet 16, the fourth return feeder 17 can also be set separately at the bottom of the third cyclone separator 6, and the dust is directly sent to the semi-coke material inlet 15 (as shown in the figure shown in 2).

The interior of the fluidized bed gasifier 3 is divided into an air chamber, a dense-phase area and a dilute-phase area from bottom to top; among them, the gasification agent inlet 2 is connected with the air chamber, and the solid fuel feeding port 1 is located in the middle of the dense-phase area. The orifice 13 is located at the top of the dense phase area, and the syngas outlet is located at the top of the dilute phase area. The interior of the fluidized bed combustion furnace 10 is also divided into an air chamber, a dense phase area and a dilute phase area from bottom to top; wherein, the air inlet 11 is connected to the air chamber, the semi-coke material inlet 15 is located in the middle of the dense phase area, and the flue gas outlet is located in the middle of the dense phase area. The top of the dilute phase region.

The method for utilizing the above-mentioned device to realize the staged conversion of solid fuel double fluidized bed partial gasification, specifically includes:

(1) Add coal powder and/or biomass dry powder to the fluidized bed gasification furnace 3 through the solid fuel feed port 1, mix with the gasification agent from the bottom in the dense phase zone and undergo a gasification reaction to generate synthesis gas;

Control the mass ratio of solid fuel and gasification agent to partially gasify the solid fuel; the gasification agent is a water vapor-oxygen mixture or a carbon dioxide-oxygen mixture; the fluidized bed gasifier operates under normal pressure or under pressure, and under pressure The hourly pressure is 0.1-5MPa, the operating temperature is 900-1000°C; in the gasification agent, the mass ratio of water vapor to solid fuel is 0.1-0.5, the mass ratio of oxygen to solid fuel is 0.3-1, and the mass ratio of carbon dioxide to solid fuel The mass ratio is 0.2-0.8;

(2) The synthetic gas discharged from the fluidized bed gasifier 3 is dedusted by the one-stage or two-stage cyclone separators 5 and 6, and then sent to the discharge pipeline; the separated dust is fed by the first feeder 4 or the fourth feeder 17 to the semi-coke material inlet of the fluidized bed combustion furnace, or sent back to the dense phase zone of the fluidized bed gasifier 3 for re-reaction;

(3) The semi-coke material obtained by the gasification reaction is discharged from the overflow port at the top of the fluidized bed gasification furnace 3 dense-phase areas, and is sent to the semi-coke material inlet of the fluidized bed combustion furnace by the feeder 14; In the dense-phase area in the bed combustion furnace, the semi-coke material and the air from the bottom undergo a combustion reaction to generate high-temperature flue gas with a temperature of 900-950 °C;

Control the mass ratio of the air at the bottom and the material at the entrance of the semi-coke material to 1-1.2, so that the semi-coke material is completely combusted; the fluidized bed combustion furnace 10 is operated under normal pressure or under pressure, and the pressure during pressurized operation is 0.1-5MPa; The operating temperature is 900-950°C;

(4) The flue gas discharged from the fluidized bed combustion furnace 10 is dedusted by the cyclone separator 8 and then sent to the discharge pipeline, and the separated dust is sent back to the semi-coke material inlet 15 of the fluidized bed combustion furnace 10 by the feeder 9 , to carry out the combustion reaction again.

In the present invention, the solid fuel may be biomass dry powder or coal powder. Biomass dry powder refers to the dry powder of crop straw, the particle size of which is less than 10mm; the particle size of coal powder is less than 8mm.

Specific application examples:

The pulverized coal is fed to the dense-phase area of the fluidized bed gasifier 3 through the solid fuel feed port 1, the coal feed rate is 4320t/d, mixed with the water vapor/oxygen from the bottom, the oxygen-coal ratio is 0.46, and the steam coal The ratio is 0.15. In order to control the amount of tar produced by gasification, the temperature of the fluidized bed gasifier 3 is controlled at about 980°C. The fluidized bed gasifier operates under normal pressure or pressurized operation, and the pressure during pressurized operation is 0.1-5MPa. In the fluidized bed gasifier 3, coal powder reacts with water vapor and oxygen to generate synthesis gas. The synthesis gas flow rate is 286955.26m ³ /h, and it leaves the fluidized bed gasifier through a two-stage cyclone separator. The syngas can be used for power generation, domestic gas, etc., and the semi-coke and fly ash separated by the two-stage cyclone separator are transported to the fluidized bed combustion furnace 10 through the first return feeder 4 for combustion. The main feed of the fluidized bed combustion furnace 10 is the semi-coke material from the fluidized bed gasification furnace 3 . In the fluidized bed gasification furnace 3, the semi-coke material produced by the partial gasification of the solid fuel overflows from the overflow port 13 at the top of the dense phase zone, and is directly transported to the fluidized bed combustion furnace 10 through the third feeder 14. The feed rate of coke material is 17804.9kg/h. In the fluidized bed combustion furnace 10, the semi-coke material is combusted with air to produce high-temperature flue gas, the air flow rate is 17804.9-21365.9kg/h, and the high-temperature flue gas generated by combustion carries high-temperature material into the second cyclone separator 8 for separation The obtained high-temperature material is sent back to the fluidized bed combustion furnace 10 through the second feeder 9 . The operating temperature of the fluidized bed combustion furnace 10 is 900-950° C., and it operates under normal pressure or pressurized operation, and the pressure during pressurized operation is 0.1-5 MPa.

Claims (5)

1. A solid fuel double fluidized bed partial gasification graded conversion device, comprising a fluidized bed combustion furnace provided with a slagging outlet, characterized in that it also includes a fluidized bed gasification furnace; The bottom of the fluidized bed gasification furnace is provided with a gasification agent inlet, the middle and lower part is provided with a solid fuel feeding port, the middle part is provided with an overflow port, and the top is provided with a synthesis gas outlet; the bottom of the fluidized bed combustion furnace is provided with an air inlet, A semi-coke material inlet is provided at the middle and lower part, and a flue gas outlet is provided at the top; the overflow port is connected to the semi-coke material inlet through a pipeline through the fourth return device; On the synthesis gas discharge pipeline connected to the synthesis gas outlet, there is a first cyclone separator; the bottom of the first cyclone separator is connected to the semi-coke material inlet through the first feeder, or connected to the fluidized bed The inlet of circulating material in the middle and lower part of the gasifier; A second cyclone separator is arranged on the pipeline connected with the flue gas outlet; the bottom of the second cyclone separator is connected to the semi-coke material inlet through the second feeder. 2. device according to claim 1, is characterized in that, also comprises the 3rd cyclone separator that is located on the first cyclone separator top outlet synthesis gas discharge pipeline; The top of the 3rd cyclone separator joins synthesis gas discharge pipe The bottom is connected to the pipeline at the outlet of the first feeder, or connected to the semi-coke material inlet through the third feeder. 3. The device according to claim 1, characterized in that, the interior of the fluidized bed gasifier is divided into an air chamber, a dense phase area and a dilute phase area from bottom to top; wherein, the gasification agent inlet and the air chamber The solid fuel feed port is located in the middle of the dense-phase area, the overflow port is located at the top of the dense-phase area, and the synthesis gas outlet is located at the top of the dilute-phase area; the interior of the fluidized bed combustion furnace is divided into an air chamber, a dense-phase The air inlet is connected to the air chamber, the semi-coke material inlet is located in the middle of the dense phase area, and the flue gas outlet is located at the top of the dilute phase area. 4. based on the solid fuel double fluidized bed partial gasification fractional conversion method of the described device of claim 1, it is characterized in that, comprising: (1) Add coal powder or biomass dry powder to the fluidized bed gasification furnace through the solid fuel feed port, and mix with the gasification agent from the bottom in the dense phase zone to generate syngas; Control the mass ratio of solid fuel and gasification agent to partially gasify the solid fuel; the gasification agent is a water vapor-oxygen mixture or a carbon dioxide-oxygen mixture; the fluidized bed gasifier operates under normal pressure or under pressure, and under pressure The hourly pressure is 0.1-5MPa, the operating temperature is 900-1000°C; in the gasification agent, the mass ratio of water vapor to solid fuel is 0.1-0.5, the mass ratio of oxygen to solid fuel is 0.3-1, and the mass ratio of carbon dioxide to solid fuel The mass ratio is 0.2-0.8; (2) The synthetic gas discharged from the fluidized bed gasifier is dedusted by a one-stage or two-stage cyclone separator, and then sent to the discharge pipeline; the separated dust is sent to the semi-coke material inlet of the fluidized bed combustion furnace by the return feeder , or sent back to the dense-phase zone of the fluidized bed gasifier for re-reaction; (3) The semi-coke material obtained from the gasification reaction is discharged from the overflow port at the top of the dense-phase zone of the fluidized bed gasifier, and sent to the semi-coke material inlet of the fluidized bed combustion furnace by the return device; it is burned in the fluidized bed In the dense-phase area of the furnace, the semi-coke material reacts with the air from the bottom to generate high-temperature flue gas at a temperature of 900-950 °C; Control the mass ratio of the air at the bottom and the material at the entrance of the semi-coke material to 1-1.2, so that the semi-coke material can be completely combusted; the fluidized bed combustion furnace is operated under normal pressure or pressurization, and the pressure is 0.1-5MPa during pressurized operation; The temperature is 900-950°C; (4) The flue gas discharged from the fluidized bed combustion furnace is dedusted by the cyclone separator and then sent to the discharge pipeline, and the separated dust is sent back to the semi-coke material inlet of the fluidized bed combustion furnace by the return device, and the combustion reaction is carried out again . 5 . The method according to claim 4 , wherein the dry biomass powder refers to dry powder of crop stalks, the particle size of which is less than 10 mm; the particle size of the coal powder is less than 8 mm.