A kind of alkali recovery boiler dissolving tank exhaust structure

Abstract

This utility model discloses an exhaust structure for a dissolving tank in an alkali recovery boiler, including a dissolving tank shell, an exhaust pipe installed on the dissolving tank shell, an exhaust pipe connecting box inside the dissolving tank, an outlet of the exhaust pipe connecting box connected to the inlet of the exhaust pipe, a grid installed at the inlet of the exhaust pipe connecting box, and flushing pipes installed on both the exhaust pipe connecting box and the grid, with the flushing pipes connected to pipes, allowing water to flow into the exhaust pipe connecting box along the pipes and flushing pipes; when gas passes through the grid, dust and unvaporized liquid droplets in the gas are captured by the grid, purifying the gas discharged through the dissolving tank by using the grid, reducing the dust content of the discharged gas and increasing the dryness of the gas, and the flushing pipes are installed to periodically flush the exhaust pipe connecting box and the grid, reducing the risk of sodium salt caking and corrosion in the exhaust pipe, and improving the continuous operation cycle of the system.

Description

Technical Field

[0001] This utility model belongs to the technical field of alkali recovery boilers, specifically relating to an exhaust structure for the dissolution tank of an alkali recovery boiler. Background Technology

[0002] In the alkali recovery process of the pulp and paper industry, the alkali recovery boiler (referred to as "alkali furnace" or "black liquor furnace") produces molten material through combustion. The main components of this molten material are sodium carbonate and sodium sulfide. This molten material enters the dissolving tank through a molten material chute at the bottom of the furnace, where it is directly mixed with dilute white liquor and cooled and dissolved. The resulting green liquor enters the causticizing section, an important process in the chemical or alkali production industry, used to produce caustic alkali. Specifically, this refers to the process of converting sodium carbonate and other substances into sodium hydroxide (NaOH) or potassium hydroxide (KOH) through a chemical reaction. The causticizing section completes and recovers the alkali solution, essentially recycling the alkali solution throughout the entire papermaking process, reducing costs and pollution.

[0003] The dissolving tank is one of the core pieces of equipment in the alkali recovery process of pulping, and its proper operation is crucial to the entire system. High-temperature molten material entering the dissolving tank generates a large amount of water vapor. This water vapor must be discharged along with the gas in a timely manner to ensure normal pressure within the dissolving tank. As the gas is discharged, dust carried by it adheres to the exhaust pipes. The dust carried in the gas is mainly sodium salt, and the high moisture content of the exhaust gas makes it prone to condensation, thus accelerating pipe blockage and corrosion, affecting the normal operation of the equipment. Therefore, an innovative technology is urgently needed to reduce the dust content of the discharged gas and increase its dryness to reduce the risk of pipe blockage and corrosion. Summary of the Invention

[0004] The purpose of this invention is to provide an exhaust structure for the dissolving tank of an alkali recovery boiler, so as to reduce the dust content of the exhaust gas and increase the dryness of the gas, reduce sodium salt caking, blockage and corrosion in the exhaust pipe, improve the continuous operation cycle of the system, and enhance the economic benefits of operation.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] An exhaust structure for a dissolving tank in an alkali recovery boiler includes a dissolving tank shell, an exhaust pipe installed on the dissolving tank shell, an exhaust pipe connection box inside the dissolving tank, an outlet of the exhaust pipe connection box connected to the inlet of the exhaust pipe, a grating installed at the inlet of the exhaust pipe connection box, flushing pipes installed on both the exhaust pipe connection box and the grating, and water flowing into the exhaust pipe connection box along the pipes and the flushing pipes.

[0007] Furthermore, the exhaust pipe connecting box is in the shape of a cuboid, with a grille on one side of the cuboid and flushing pipes on the four sides of the cuboid excluding the top and bottom surfaces.

[0008] Furthermore, the exhaust pipe connecting box is installed inside the dissolving tank and located below the exhaust pipe. An opening is provided on the top surface of the dissolving tank shell, and the bottom inlet of the exhaust pipe corresponds to the opening on the top surface of the dissolving tank shell.

[0009] Furthermore, the exhaust pipe connection box is arranged below the top opening of the dissolving tank shell corresponding to the exhaust pipe, the outlet of the exhaust pipe connection box is set at the opening on the top surface of the dissolving tank shell, and the bottom inlet of the exhaust pipe is connected to the outlet of the exhaust pipe connection box through the opening on the top surface of the dissolving tank shell.

[0010] Furthermore, when the exhaust pipe connecting box is located inside the dissolving tank, the outlet end of the flushing pipe is located inside the dissolving tank, and the inlet end of the flushing pipe extends out from the dissolving tank shell.

[0011] Furthermore, the lower part of the exhaust pipe connecting box is located inside the dissolving tank, and the upper part is located outside the dissolving tank. The outlet of the exhaust pipe connecting box outside the dissolving tank is connected to the exhaust pipe, and a grille is installed at the inlet of the exhaust pipe connecting box inside the dissolving tank.

[0012] Furthermore, when the lower part of the exhaust pipe connecting box is located inside the dissolving tank and the upper part is located outside the dissolving tank, the outlet end of the flushing pipe located on the grille is located inside the dissolving tank, and the inlet end extends from the dissolving tank shell. The flushing pipes located on the three sides of the exhaust pipe connecting box are located outside the dissolving tank.

[0013] Furthermore, the dissolving tank shell is provided with multiple circulating water inlets, which are connected to an external water source through pipes. The inlet of the rinsing pipe is connected to a pipe, and the pipe connected to the inlet of the rinsing pipe is connected to the pipe between the circulating water inlet and the external water source.

[0014] Furthermore, the exhaust pipe is inclined at the bottom of the connecting box.

[0015] Furthermore, the angle between the bottom surface of the exhaust pipe connecting box and the horizontal plane is 10°~20°.

[0016] The beneficial effects of this utility model are:

[0017] In this invention, a grille is installed at the inlet of the exhaust pipe connecting box. When the gas passes through the grille, dust and unvaporized liquid droplets in the gas are captured by the grille. The grille is used to purify the gas discharged through the dissolution tank, reducing the dust content of the discharged gas and increasing the dryness of the gas. A flushing pipe is installed to regularly flush the exhaust pipe connecting box and the grille, reducing the risk of sodium salt caking, blockage and corrosion in the exhaust pipe, increasing the continuous operation cycle of the system and improving the economic efficiency of operation. Attached Figure Description

[0018] Figure 1This is a front view of the venting structure of the dissolution tank in this utility model.

[0019] Figure 2 This is a top view of the venting structure of the dissolution tank in this utility model.

[0020] Figure 3 This is a side view of the exhaust structure of the dissolution tank in this utility model.

[0021] In the diagram: 1-Dissolving tank shell, 2-Exhaust pipe, 3-Exhaust pipe connecting box, 4-Grate, 5-Flushing pipe. Detailed Implementation

[0022] To make the purpose, technical solution and advantages of this utility model clearer, the present utility model will be further described below with reference to the accompanying drawings.

[0023] like Figure 1 , Figure 2 , Figure 3 The exhaust structure of the alkali recovery boiler dissolving tank shown includes a dissolving tank shell 1, an exhaust pipe 2, an exhaust pipe connecting box 3, a grille 4, and a flushing pipe 5.

[0024] The exhaust pipe 2 is located at the top of the melting tank shell 1, with its top outlet protruding from the outer surface of the melting tank shell 1. The top outlet of the exhaust pipe 2 is connected to a downstream process system to recover the heat energy discharged from the exhaust pipe 2. The bottom inlet of the exhaust pipe 2 is connected to the outlet of the exhaust pipe connecting box 3.

[0025] In one embodiment of this utility model, an exhaust pipe connecting box 3 is disposed within a dissolving tank. The exhaust pipe connecting box 3 is located below the exhaust pipe 2. An opening is provided on the top surface of the dissolving tank housing 1. The bottom inlet of the exhaust pipe 2 corresponds to the opening on the top surface of the dissolving tank housing 1. The exhaust pipe connecting box 3 is positioned below the opening on the top surface of the dissolving tank housing 1 corresponding to the exhaust pipe 2. The outlet of the exhaust pipe connecting box 3 is located at the opening on the top surface of the dissolving tank housing 1. The bottom inlet of the exhaust pipe 2 communicates with the outlet of the exhaust pipe connecting box 3 through the opening. A grille 4 is provided at the inlet of the exhaust pipe connecting box 3. The exhaust pipe connecting box 3 is rectangular, and the grille 4 serves as one side of the rectangular parallelepiped. The grille surface has a mesh structure and is made of corrosion-resistant stainless steel.

[0026] In another embodiment of this utility model, the lower part of the exhaust pipe connecting box 3 is located inside the dissolving tank, and the upper part is located outside the dissolving tank. The outlet of the exhaust pipe connecting box 3 outside the dissolving tank is connected to the exhaust pipe 2, and a grille 4 is provided at the inlet of the exhaust pipe connecting box 3 inside the dissolving tank.

[0027] A flushing pipe 5 is installed on the exhaust pipe connecting box 3 and the grille 4. The exhaust pipe connecting box 3 is generally rectangular, with the grille 4 installed on one side of the cuboid. The flushing pipe 5 can be installed on the four sides of the cuboid, excluding the top and bottom surfaces. As a preferred embodiment, four flushing pipes 5 can be installed, with one flushing pipe 5 located on the upper part of the grille 4 and the other three flushing pipes 5 located on the upper parts of the other three sides of the cuboid. The flushing pipes are used to flush the exhaust pipe connecting box 3 and the grille 4 after the exhaust structure of the alkali recovery boiler dissolving tank has been in operation for a period of time, removing deposits from the exhaust pipe connecting box 3 and the grille 4. The deposits include, but are not limited to, salt particles or plate-shaped salt blocks.

[0028] The dissolving tank shell 1 has multiple circulating water inlets, which are connected to an external water source via pipes. A pipe is connected to the inlet of the flushing pipe 5, which connects to the pipe between the circulating water inlets and the external water source. Water enters the exhaust pipe connection box 3 to flush the exhaust pipe connection box 3. In a preferred embodiment, a valve can be installed on the pipe connected to the inlet of the flushing pipe 5, which can be opened or closed remotely. The flushing pipe 5 is arranged above the grille 4 and the exhaust pipe connection box 3, periodically flushing the grille 4 and the exhaust pipe connection box 3 to ensure unobstructed flow and facilitate long-term stable exhaust from the dissolving tank.

[0029] Due to space constraints, the exhaust pipe connecting box 3 can be entirely located inside the dissolving tank, or the lower part of the exhaust pipe connecting box 3 can be located inside the dissolving tank while the upper part can be located outside the dissolving tank. The flushing pipe 5 on the exhaust pipe connecting box 3 is located on the top surface of the exhaust pipe connecting box 3 or on the upper side of the exhaust pipe connecting box 3, so as to flush the exhaust pipe connecting box 3.

[0030] When the exhaust pipe connecting box 3 is located inside the dissolving tank, the outlet end of the flushing pipe 5 is located inside the dissolving tank, and the inlet end can extend from the dissolving tank shell 1. The inlet end of the flushing pipe 5 is located outside the dissolving tank so that the pipe connected at the inlet of the flushing pipe 5 can be connected to the pipe between the circulating water inlet on the dissolving tank shell 1 and the external water source.

[0031] When the lower part of the exhaust pipe connecting box 3 is located inside the dissolving tank and the upper part is located outside the dissolving tank, the outlet end of the flushing pipe 5 located on the grid 4 is located inside the dissolving tank and the inlet end is located outside the dissolving tank. The flushing pipes 5 located on the three sides of the exhaust pipe connecting box 3 can be located entirely outside the dissolving tank, and the pipe connected at the inlet of the flushing pipe 5 is connected to the pipe between the circulating water inlet on the dissolving tank shell 1 and the external water source.

[0032] In this invention, the dust carried in the gas mainly refers to sodium salts. A grid 4 is installed at the inlet of the exhaust pipe connecting box 3. Dust and unvaporized liquid droplets in the gas are captured by the grid 4 to separate the gas from the dissolved gas, increasing the gas's dryness. Simultaneously, the grid captures dust carried in the gas, thus pre-purifying the gas entering the exhaust pipe 2. The water vapor-containing gas entering the dissolved tank passes through the grid 4 into the exhaust pipe connecting box 3. The gas flows from the inlet to the outlet of the exhaust pipe connecting box 3 and then exits from the exhaust pipe 2. The bottom of the exhaust pipe connecting box 3 is inclined, with an angle of 10°~20° to the horizontal plane. This facilitates the return of condensate and flushing water in the exhaust pipe connecting box 3 to the dissolved tank after passing through the grid 4. The flow rate of water entering along the flushing pipe 5 is slightly faster than the flow rate of water exiting the exhaust pipe connecting box 3 through the grid 4.

[0033] The working process of the fluidized bed boiler designed in this utility model is as follows:

[0034] During operation, the molten salt or appropriately cooled high-temperature solid salt produced by the alkali recovery boiler dissolves in the dissolving tank, generating a large amount of gas. This gas, carrying dust (sodium salt) and water vapor, passes through the grille 4 and enters the exhaust pipe connection box 3, then through the exhaust pipe 2 to connect to the subsequent process system for heat recovery. As the gas passes through the grille 4, dust and unvaporized liquid droplets are captured. The grille 4 purifies the gas discharged from the dissolving tank, reducing the dust content and increasing the dryness of the gas, thus minimizing sodium salt caking, blockage, and corrosion in the exhaust pipe and subsequent process system. Simultaneously, the exhaust pipe connection box 3 and the grille 4 are periodically flushed through the flushing pipe 5, with particularly short flushing intervals for the grille 4. This reduces sodium salt caking, blockage, and corrosion in the exhaust pipe and subsequent process system, ensuring long-term stable operation of the entire alkali recovery system and improving its economic efficiency.

[0035] In the description of this utility model, it should be understood that the terms "upper", "lower", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

Claims

1. An alkali recovery boiler dissolving tank exhaust structure comprising a dissolving tank shell (1), an exhaust pipe (2) provided on the dissolving tank shell (1), characterized in that: The dissolving tank is equipped with an exhaust pipe connection box (3), the outlet of the exhaust pipe connection box (3) is connected to the inlet of the exhaust pipe (2), and a grid (4) is installed at the inlet of the exhaust pipe connection box (3). A flushing pipe (5) is installed on both the exhaust pipe connection box (3) and the grid (4). The flushing pipe (5) is connected to a pipeline. The flushing pipe (5) is used to flush the exhaust pipe connection box and / or the grid after the exhaust structure of the alkali recovery boiler dissolving tank has been running for a period of time.

2. The alkali recovery boiler dissolving tank exhaust structure according to claim 1, characterized by: The flushing pipe (5) is located on the four sides of the exhaust pipe connecting box (3), excluding the top and bottom surfaces.

3. The alkali recovery boiler dissolving tank exhaust structure according to claim 1, characterized by: The exhaust pipe connecting box (3) is set inside the dissolving tank and located below the exhaust pipe (2). The top surface of the dissolving tank shell (1) has an opening, and the bottom inlet of the exhaust pipe (2) corresponds to the opening on the top surface of the dissolving tank shell (1).

4. The alkali recovery boiler dissolving tank exhaust structure according to claim 3, characterized by: The exhaust pipe connection box (3) is arranged below the top opening of the dissolution tank shell (1) corresponding to the exhaust pipe (2). The outlet of the exhaust pipe connection box (3) is set at the opening on the top surface of the dissolution tank shell (1). The bottom inlet of the exhaust pipe (2) is connected to the outlet of the exhaust pipe connection box (3) through the opening on the top surface of the dissolution tank shell (1).

5. The alkali recovery boiler dissolving tank exhaust structure according to claim 3, characterized by: When the exhaust pipe connecting box (3) is located inside the dissolving tank, the outlet end of the flushing pipe (5) is located inside the dissolving tank, and the inlet end of the flushing pipe (5) extends from the dissolving tank shell (1).

6. The alkali recovery boiler dissolving tank exhaust structure according to claim 1, characterized by: The lower part of the exhaust pipe connecting box (3) is located inside the dissolving tank, and the upper part is located outside the dissolving tank. The outlet of the exhaust pipe connecting box (3) outside the dissolving tank is connected to the exhaust pipe (2). A grille (4) is set at the entrance of the exhaust pipe connecting box (3) inside the dissolving tank.

7. The alkali recovery boiler dissolving tank exhaust structure according to claim 1, characterized by: The dissolving tank shell (1) is provided with multiple circulating water inlets. The circulating water inlets are connected to an external water source through pipes. The inlet of the flushing pipe (5) is connected to a pipe. The pipe connected to the inlet of the flushing pipe (5) is connected to the pipe between the circulating water inlet and the external water source.

8. The alkali recovery boiler dissolving tank exhaust structure according to claim 1, characterized by: The bottom surface of the exhaust pipe connecting box (3) is inclined.

9. The alkali recovery boiler dissolving tank exhaust structure according to claim 8, characterized by: The angle between the bottom surface of the exhaust pipe connecting box (3) and the horizontal plane is 10°~20°.

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