Continuous deslagging system and deslagging method of circulating fluidized bed gas furnace

Abstract

The invention discloses a continuous deslagging system and method of a circulating fluidized bed gas furnace, and belongs to the technical field of coal gasification equipment. The continuous slag discharging system comprises a slag discharging pipe, the slag discharging pipe is connected with an inlet of a spiral conveyor through a rotary discharging machine, an outlet of the spiral conveyor is connected with an inlet of a material conveyor through a rotary feeding machine, and an outlet of the material conveyor is connected with an inlet of a slag bin. An outlet of the material conveyor is connected with a bag-type dust collector through an air inducing pipe, and an ash falling opening of the bag-type dust collector is connected with an inlet of the slag bin; water cooling jackets externally connected with circulating cooling water are arranged in shells of the slag discharging pipe and the spiral conveyor, an inert gas connector is arranged at an inlet of the rotary feeder, and the inert gas connector is externally connected with a gas source through a gas pipeline. According to the deslagging method, the deslagging system is adopted, the problems of sealing performance, cooling efficiency and safety in the deslagging process of the high-temperature slag can be solved, and normal work of the circulating fluidized bed gas furnace is guaranteed.

Description

Technical Field

[0001] This invention belongs to the technical field of coal gasification equipment, and more specifically, relates to a continuous slag discharge system and slag discharge method for a circulating fluidized bed coal gasifier. Background Technology

[0002] A circulating fluidized bed gasifier is a highly efficient and clean coal gasification device. During its operation, it produces high-temperature slag (typically at 900-950℃), which needs to be continuously or intermittently discharged from the furnace to maintain a stable bed feed rate and reaction environment inside the furnace.

[0003] Currently, existing slag removal methods face the following main technical challenges: 1. Air tightness issue: The slag outlet is the key point that compromises the air tightness of the furnace. Simple flap valve seals are prone to failure in high-temperature and high-dust environments, leading to high-pressure gas leakage, causing serious safety hazards (poisoning, explosion), and also resulting in the loss of combustible gases and reduced gasification efficiency.

[0004] 2. Cooling Issues: Poor cooling performance results in the direct discharge of high-temperature slag, which is not only difficult to handle but also wastes a large amount of sensible heat, leading to low energy efficiency. While water quenching can cool the slag particles, it wastes heat energy and generates large amounts of dust-laden steam, causing environmental pollution.

[0005] 3. Safety issues: If the cold slag equipment has poor sealing, a gas leak may come into contact with the high-temperature red slag, which could potentially cause a flash explosion.

[0006] For example, Chinese patent application number CN202011407530.X, published on April 2, 2021, discloses a circulating fluidized bed coal gasification method, the steps of which are as follows: coal is fed into a fluidized bed coal gasifier; fluidizing gas is introduced into the bottom of the coal gasifier, the fluidizing gas containing at least oxygen and water vapor, the amount of oxygen being only for the combustion of a portion of the coal, the portion of coal being burned in the coal gasifier consuming oxygen and simultaneously releasing heat that can heat the coal to a temperature that can react with water vapor to generate coal gas; gasification gas and ash are produced through combustion and gasification reaction, the gasification gas carrying semi-coke fine powder is discharged from the top of the coal gasifier and enters a cyclone separator for gas-solid separation, the ash is discharged from the bottom of the coal gasifier and is transported to an ash cooler through an ash elevator for gas-solid separation.

[0007] In this scheme, although the slag is transported to the cooler for cooling after being discharged from the bottom of the coal gasification furnace, the sealing and safety issues during the discharge process are difficult to guarantee.

[0008] For example, Chinese patent application number CN202110720180.0, published on September 7, 2021, discloses a fluidized bed incinerator with a slag cooling structure and its usage method. The incinerator includes an inclined support plate, with a first connecting plate and a second connecting plate sequentially installed on the top of the inclined support plate, and stable support bases symmetrically installed at the bottom of the inclined support plate. A cooling drum is arranged between the first and second connecting plates. An arc-shaped cover is installed on the side of the cooling drum near the second connecting plate, and the arc-shaped cover is connected to the second connecting plate via a second connecting pipe. The cooling drum is connected to the first connecting plate via a first connecting pipe. Multiple cooling holes are opened on the annular side of the cooling drum, and a discharge port is opened on the side of the cooling drum near the arc-shaped cover. The main body of the fluidized bed incinerator is located on the right side of the first connecting pipe, and the slag discharge port on the main body of the fluidized bed incinerator is connected to the first connecting pipe via a discharge pipe. A filter screen is connected to the inner wall of the cooling drum.

[0009] This scheme is similar to the previous one, mainly focusing on measures for cooling the slag, but it neglects the sealing and safety issues during the slag removal process.

[0010] Therefore, there is an urgent need for a new type of slag removal system that can simultaneously solve the three major problems of sealing, cooling efficiency and safety. Summary of the Invention

[0011] 1. The problem to be solved To address the challenges of existing circulating fluidized bed gasifier slag removal systems in simultaneously solving the three major problems of sealing, cooling efficiency, and safety during the slag removal process, this invention provides a continuous slag removal system and method for circulating fluidized bed gasifiers. This improvement over existing slag removal systems solves the problems of sealing, cooling efficiency, and safety during the high-temperature slag removal process, ensuring the normal operation of the circulating fluidized bed gasifier.

[0012] 2. Technical Solution To solve the above problems, the present invention adopts the following technical solution.

[0013] A continuous slag removal system for a circulating fluidized bed gasifier includes a slag discharge pipe, which is connected to the inlet of a screw conveyor via a rotary feeder. The outlet of the screw conveyor is connected to the inlet of a material conveyor via a rotary feeder. The outlet of the material conveyor is connected to the inlet of a slag silo. A bag filter is connected to the outlet of the material conveyor via an induced draft pipe. The ash discharge port of the bag filter is connected to the inlet of the slag silo. The casing of the slag discharge pipe and the screw conveyor is equipped with a water-cooled jacket connected to external circulating cooling water. The inlet of the rotary feeder is equipped with an inert gas interface, which is connected to an external gas source through a gas pipeline.

[0014] As a further improvement to the technical solution, the screw conveyor is arranged at an angle, with its inlet height lower than its outlet height. As a further improvement to the technical solution, a stirring rod is provided on the screw shaft of the screw conveyor.

[0015] As a further improvement to the technical solution, the material conveyor adopts a buried scraper conveyor.

[0016] As a further improvement to the technical solution, a harmful gas detector is installed at the exhaust port of the bag filter.

[0017] As a further improvement to the technical solution, a pneumatic regulating valve is installed on the gas pipeline, and the harmful gas detector is electrically connected to the pneumatic regulating valve.

[0018] As a further improvement to the technical solution, a pneumatic slide gate valve is installed at the outlet end of the slag discharge pipe, and the harmful gas detector is electrically connected to the pneumatic slide gate valve.

[0019] A method for discharging slag from a continuous slag discharge system of the aforementioned circulating fluidized bed gasifier includes the following steps: 1. Open the control valves of the circulating cooling water connected to the water-cooled jacket of the slag discharge pipe and screw conveyor; open the inert gas interface to form an inert gas seal; start the bag filter to create negative pressure inside the material conveyor. 2. Start the rotary feeder, screw conveyor, rotary feeder and material conveyor. After passing through the rotary feeder and screw conveyor in sequence, the coal slag is conveyed into the slag bin by the rotary feeder and material conveyor under an inert gas atmosphere.

[0020] As a further improvement to the technical solution, when the hazardous gas detector detects a gas leak, it will sound an alarm and increase the opening of the pneumatic regulating valve to increase the input flow rate of inert gas.

[0021] As a further improvement to the technical solution, if the harmful gas detector can still detect gas leakage after the set time exceeds the opening degree of the pneumatic regulating valve, then the pneumatic slide gate valve will be closed.

[0022] 3. Beneficial effects Compared with the prior art, the present invention has the following beneficial effects.

[0023] (1) The continuous slag discharge system of the circulating fluidized bed gasifier of the present invention can achieve a triple sealing effect. First, the rotary feeder, screw conveyor and rotary feeder are used for material conveying. The blades cooperate with the shell to achieve material sealing during the rotation process, which is a mechanical seal. Second, the rotary feeder is introduced with inert gas so that it can form positive pressure protection during the material feeding process, which effectively prevents gas leakage, which is an inert gas seal. Third, the bag filter can form a negative pressure state inside the material conveyor after it is turned on, which prevents dust and trace gas from escaping, which is a negative pressure seal. Through the triple sealing effect, the sealing performance of the slag discharge system is effectively improved, the possibility of gas leakage and flash explosion is reduced, and the working safety of the slag discharge system is guaranteed.

[0024] (2) The continuous slag discharge system of the circulating fluidized bed gasifier of the present invention is provided with a water-cooled jacket in the shell of the slag discharge pipe and the screw conveyor, which realizes the step-by-step cooling of the slag during the slag discharge process and has a better cooling effect. The stirring rod in the screw conveyor can agitate and turn the slag during the conveying process, completely breaking the phenomenon of "cold shell and hot core" of the slag, so that the high temperature slag in the central area can also be effectively cooled, significantly improving the cooling uniformity and efficiency.

[0025] (3) The continuous slag discharge system of the circulating fluidized bed gasifier of the present invention has an inclined arrangement of screw conveyor, which increases the bulk density of the material, reduces the porosity, and further enhances the material sealing effect.

[0026] (4) The present invention provides a method for continuous slag discharge system of circulating fluidized bed gasifier. Through the linkage of harmful gas detector, pneumatic regulating valve and pneumatic slide valve, the gas leakage of slag discharge system can be monitored in real time, and timely adjustment can be made when gas leakage occurs. The slag discharge system is forced to inert, and the discharge of coal slag is stopped when the problem is not resolved for a long time, thus preventing the occurrence of flash explosion and effectively ensuring the working safety of slag discharge system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the continuous slag discharge system of a circulating fluidized bed gasifier; In the diagram: 1. Slag discharge pipe; 2. Rotary feeder; 3. Screw conveyor; 4. Agitator; 5. Rotary feeder; 6. Material conveyor; 7. Bag filter; 8. Pneumatic regulating valve; 9. Harmful gas detector; 10. Slag bin; 11. Pneumatic slide gate valve. Detailed Implementation

[0028] Exemplary embodiments of the present invention are described in detail below. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from its spirit and scope. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and does not limit the description of the features and characteristics of the invention, in order to suggest the best mode for carrying out the invention and to enable those skilled in the art to practice it. Therefore, the scope of the invention is defined only by the appended claims.

[0029] Example 1 A continuous slag discharge system for a circulating fluidized bed gasifier is provided for the discharge and treatment of coal slag during the operation of the circulating fluidized bed gasifier. Its specific structure and technical effects are described in detail below.

[0030] like Figure 1 As shown, the continuous slag discharge system includes a slag discharge pipe 1, which is connected to the inlet of a screw conveyor 3 via a rotary feeder 2. The outlet of the screw conveyor 3 is connected to the inlet of a material conveyor 6 via a rotary feeder 5. The outlet of the material conveyor 6 is connected to the inlet of a slag silo 10, and the outlet of the material conveyor 6 is connected to a bag filter 7 via an exhaust pipe. The ash discharge port of the bag filter 7 is connected to the inlet of the slag silo 10. The material conveyor 6 is a submerged scraper conveyor, which has good sealing performance and can work well with the bag filter 7 to create an internal negative pressure state.

[0031] The slag discharge pipe 1 and the screw conveyor 3 are equipped with water-cooled jackets connected to external circulating cooling water. The inlet of the rotary feeder 5 is equipped with an inert gas interface, which is connected to an external gas source through a gas pipeline. In this embodiment, nitrogen is used as the inert gas, and a stirring rod 4 is installed on the screw shaft of the screw conveyor 3.

[0032] Compared to conventional slag removal methods in circulating fluidized bed gasifiers, the continuous slag removal system in this embodiment achieves a triple sealing effect. First, it uses a rotary feeder 2, a screw conveyor 3, and a rotary feeder 5 for material conveying; the blades cooperate with the shell during rotation to achieve a material seal—this is a mechanical seal. Second, the rotary feeder 5 is supplied with inert gas, creating positive pressure protection during material feeding and effectively preventing gas leakage—this is an inert gas seal. Third, the bag filter 7, when activated, creates a negative pressure state inside the material conveyor 6, preventing dust and trace amounts of gas from escaping—this is a negative pressure seal. Through this triple sealing effect, the sealing performance of the slag removal system is effectively improved, reducing the possibility of gas leakage and flash explosions, and ensuring the operational safety of the slag removal system.

[0033] Meanwhile, the water-cooled jackets installed inside the shells of the slag discharge pipe 1 and the screw conveyor 3 enable the slag to be cooled in a step-by-step manner during the slag discharge process, resulting in a better cooling effect. The stirring rod 4 inside the screw conveyor 3 can agitate and tumble the slag during transportation, completely breaking the phenomenon of "cold shell and hot core" in the slag, so that the high-temperature slag in the central area can also be effectively cooled, significantly improving the cooling uniformity and efficiency.

[0034] In this embodiment, the screw conveyor 3 is arranged at an inclination, with its inlet height lower than its outlet height. This inclination arrangement increases the bulk density of the material, reduces the porosity, and further enhances the material sealing effect.

[0035] In addition, a hazardous gas detector 9 is installed at the exhaust port of the bag filter 7, a pneumatic regulating valve 8 is installed on the gas pipeline, and a pneumatic slide valve 11 is installed at the outlet end of the slag discharge pipe 1. The hazardous gas detector 9 is electrically connected to the pneumatic regulating valve 8 and the pneumatic slide valve 11. Through the linkage of the hazardous gas detector 9, the pneumatic regulating valve 8, and the pneumatic slide valve 11, the gas leakage of the slag discharge system can be monitored in real time. When a gas leakage occurs, adjustments can be made in a timely manner to forcibly inertize the slag discharge system. If the problem is not resolved for a long time, the discharge of slag can be stopped, preventing the occurrence of flash explosions and effectively ensuring the operational safety of the slag discharge system.

[0036] The specific slag removal method of this continuous slag removal system is described below, which includes the following steps: 1. Open the control valves of the circulating cooling water connected to the water-cooled jacket of the slag discharge pipe 1 and the screw conveyor 3; open the inert gas interface to form an inert gas seal; start the bag filter 7 to form a negative pressure inside the material conveyor 6.

[0037] 2. Start the rotary feeder 2, screw conveyor 3, rotary feeder 5 and material conveyor 6. After passing through the rotary feeder 2 and screw conveyor 3 in sequence, the coal slag is conveyed into the slag bin 10 by the rotary feeder 5 and material conveyor 6 under an inert gas atmosphere.

[0038] When the hazardous gas detector 9 detects a gas leak, it alarms and increases the opening of the pneumatic regulating valve 8 to increase the input flow rate of inert gas. If the hazardous gas detector 9 can still detect a gas leak after a set time, it controls the pneumatic slide gate valve 11 to close.

[0039] In summary, the continuous slag removal system and method for a circulating fluidized bed gasifier in this embodiment improves upon the existing slag removal system for circulating fluidized bed gasifiers. It can solve the problems of sealing, cooling efficiency, and safety during the high-temperature slag removal process, ensuring the normal operation of the circulating fluidized bed gasifier.

[0040] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A continuous slag discharge system for a circulating fluidized bed gasifier, characterized in that: The system includes a slag discharge pipe (1), which is connected to the inlet of a screw conveyor (3) via a rotary feeder (2). The outlet of the screw conveyor (3) is connected to the inlet of a material conveyor (6) via a rotary feeder (5). The outlet of the material conveyor (6) is connected to the inlet of a slag bin (10). The outlet of the material conveyor (6) is connected to a bag filter (7) via an exhaust pipe. The ash discharge port of the bag filter (7) is connected to the inlet of the slag bin (10). The slag discharge pipe (1) and the screw conveyor (3) are equipped with water-cooled jackets with external circulating cooling water inside their shells. The rotary feeder (5) is equipped with an inert gas interface at its inlet, and the inert gas interface is connected to an external gas source through a gas pipeline.

2. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 1, characterized in that: The screw conveyor (3) is arranged at an angle, with its inlet height lower than its outlet height.

3. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 2, characterized in that: The screw conveyor (3) is equipped with a stirring rod (4) on its screw shaft.

4. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 1, characterized in that: The material conveyor (6) is a buried scraper conveyor.

5. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 1, characterized in that: A harmful gas detector (9) is installed at the exhaust port of the bag filter (7).

6. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 5, characterized in that: A pneumatic regulating valve (8) is installed on the gas pipeline, and the harmful gas detector (9) is electrically connected to the pneumatic regulating valve (8).

7. The continuous slag discharge system for a circulating fluidized bed gasifier according to claim 6, characterized in that: The outlet end of the slag discharge pipe (1) is equipped with a pneumatic slide gate valve (11), and the harmful gas detector (9) is electrically connected to the pneumatic slide gate valve (11).

8. A slag discharge method for a continuous slag discharge system of a circulating fluidized bed gasifier according to any one of claims 1-7, characterized in that, Includes the following steps:

1. Open the control valve of the circulating cooling water connected to the water-cooled jacket of the slag discharge pipe (1) and the screw conveyor (3); open the inert gas interface to form an inert gas seal; start the bag filter (7) to form a negative pressure inside the material conveyor (6); 2. Start the rotary feeder (2), screw conveyor (3), rotary feeder (5) and material conveyor (6). After passing through the rotary feeder (2) and screw conveyor (3) in sequence, the coal slag is conveyed into the slag bin (10) by the rotary feeder (5) and material conveyor (6) under an inert gas atmosphere.

9. The slag discharge method of a continuous slag discharge system for a circulating fluidized bed gasifier according to claim 8, characterized in that: When the harmful gas detector (9) detects a gas leak, it alarms and increases the opening of the pneumatic regulating valve (8) to increase the input flow of inert gas.

10. The slag discharge method of a continuous slag discharge system for a circulating fluidized bed gasifier according to claim 9, characterized in that: If the gas leak is detected by the harmful gas detector (9) after the opening of the pneumatic regulating valve (8) is increased and the set time is exceeded, the pneumatic slide gate valve (11) will be closed.

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