Device for automatically cleaning tar and carbon deposits in heat exchange tubes for waste heat recovery of coke oven gas

Abstract

The present invention discloses a device for automatically cleaning tar and carbon deposits in a heat exchange tube for recovering waste heat from raw gas from a coke oven. The technical key points of the present invention are that the inner wall of the heat exchange tube is a threaded groove structure, a rotating rod is installed on the center line of the heat exchange tube, the upper end of the rotating rod extends out of the upper end cover of the heat exchange tube and is connected to a driving device outside the shell, a cleaning head clamping rod is connected to the lower end of the rotating rod, cleaning heads are installed at both ends of the cleaning head clamping rod, and the cleaning head and the threaded groove on the inner wall of the heat exchange tube are gap-matched; the cleaning head clamping rod and the cleaning head perform spiral rotation and reciprocating motion along the threaded groove on the inner wall of the heat exchanger driven by the rotating rod, and the cleaning head cleans the tar and carbon deposits adhering to the inner wall of the heat exchange tube during the rotational motion, and at the same time, disturbs the raw gas. The present invention solves the problem of reduced heat exchange efficiency caused by tar condensation and carbon deposits on the inner wall of the riser, and can not only recover the waste heat of raw gas to the greatest extent, but also ensure that the heat exchanger works continuously and normally under complex working conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat resource recovery and utilization of raw coal gas in the coking process, and specifically relates to a device that can automatically clean tar and carbon deposits in a coke oven waste heat recovery riser (i.e., a heat exchange tube). Background Art

[0002] The waste heat generated during the coking process is large in size and high in energy value, and has great recycling value. At present, there are two main ways to recover the waste heat from the raw gas in the coke oven: (1) replacing the coke oven riser with a water-jacketed riser, and recovering the waste heat by exchanging heat between water and raw gas in the riser; (2) after the raw gas is discharged, it is recovered in a centralized manner using a waste heat recovery device. Among them, the water-jacketed waste heat recovery method has the risk of cracking of the riser weld, water leakage, and gas leakage.

[0003] Although the method of using a waste heat recovery device to centrally recover the waste heat of raw coal gas is very efficient, the current conventional waste heat recovery device can only be used for the recovery of waste heat from cleaner exhaust gas. After the coke oven raw coal gas is heat exchanged and cooled, tar and carbon deposits will be generated, which can easily block the exhaust gas channel of the waste heat recovery device.

[0004] Therefore, the existing waste heat treatment process of raw coal gas not only fails to fully utilize the waste heat, but also wastes a large amount of energy media such as circulating ammonia water, circulating water for cooling the gas primary cooler and electricity during the treatment process, which greatly wastes resources and is not conducive to the sustainable development of the enterprise. Summary of the invention

[0005] The purpose of the present invention is to provide a device for automatically cleaning tar and carbon deposits in coke oven raw gas waste heat recovery heat exchange tubes with simple structure, convenient operation, safety and effectiveness in view of the above-mentioned deficiencies in the prior art.

[0006] The objective of the present invention is achieved through the following technical scheme: the device for automatically cleaning tar and carbon deposits in heat exchange tubes for recovering waste heat from raw coal gas from a coke oven, the heat exchanger consists of a shell and multiple rows and columns of heat exchange tubes; the inner wall of the heat exchange tube is a threaded groove structure, a rotating rod is installed on the center line of the heat exchange tube, the upper end of the rotating rod extends out of the upper end cover of the heat exchange tube and is connected to a driving device outside the shell, the lower end of the rotating rod is connected to a cleaning head clamping rod, cleaning heads are installed at both ends of the cleaning head clamping rod, and the cleaning head and the threaded groove of the inner wall of the heat exchange tube are gap-matched; the cleaning head clamping rod and the cleaning head perform spiral rotation and reciprocating motion along the threaded groove of the inner wall of the heat exchanger driven by the rotating rod, and the cleaning head cleans the tar and carbon deposits adhering to the inner wall of the heat exchange tube during the rotational motion, while applying disturbance to the raw coal gas.

[0007] Specifically, the front end of the cleaning head is axe-shaped, and its front end surface which is gap-matched with the threaded groove on the inner wall of the heat exchange tube is composed of two triangular curved surfaces of different sizes diagonally combined, and its rear end connected to the cleaning head clamping rod is a semi-cylindrical structure.

[0008] Furthermore, a plurality of radial through holes are provided on the semi-cylindrical structure at the rear end of the cleaning head, each radial through hole is connected to an axial soot blowing port on the rear end of the cleaning head close to the front end, and each radial through hole is connected to a channel provided in the clamping rod and the rotating rod of the cleaning head, through which high-temperature compressed air or sulfuric acid solution can be introduced.

[0009] Compared with the existing device for cleaning the waste heat of coke oven raw gas and recovering tar and carbon deposits in the riser, the present invention has the following beneficial effects: it solves the problem of reduced heat exchange efficiency caused by tar condensation and carbon deposits on the inner wall of the riser, can recover the waste heat of raw gas to the greatest extent, and can ensure the continuous and normal operation of the heat exchanger under complex working conditions, thereby achieving the purpose of maximizing the recovery and utilization of the waste heat of raw gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a longitudinal sectional front view of an embodiment of the present invention.

[0011] Figure 2 yes Figure 1 Cross-sectional top view.

[0012] Figure 3 yes Figure 2 An enlarged view of the dust cleaning head at position Ⅰ in the middle.

[0013] Figure 4 It is a three-dimensional picture of the cleaning head.

[0014] Figure 5 This is a three-dimensional picture of the cleaning head from another angle.

[0015] Figure 6 yes Figure 4 Bottom view of .

[0016] Figure 7 yes Figure 4 Top view of the .

[0017] Figure 8 yes Figure 4 main view. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0019] See also Figure 1 , Figure 2In this embodiment, the heat exchange tube includes an inner wall 1 and an outer wall 2. The cavity 3 between the inner wall 1 and the outer wall 2 is a water flow area. The outer surface of the outer wall 2 in contact with the air is covered with a thermal insulation material. 7 is an upper end cover, and 8 is a lower end cover. The upper and lower ends of the inner wall 1 are respectively connected to the raw gas pipeline through flanges, and the upper and lower ends of the heat exchange tube are respectively provided with a steam outlet and a water inlet. As can be seen from the figure, the inner surface of the inner wall 1 of the heat exchange tube is processed with a threaded groove 9, which is conducive to the concentrated outflow and collection of coal tar; a rotating rod 4 is installed on the center line of the heat exchange tube, the upper end of the rotating rod 4 extends out of the upper end cover 7 of the heat exchange tube and is connected to the driving device (not shown in the figure) outside the shell, and the lower end of the rotating rod 4 is connected to a cleaning head clamping rod 5, and cleaning heads 6 are installed at both ends of the cleaning head clamping rod 5. The cleaning head 6 and the threaded groove 9 of the inner wall 1 of the heat exchange tube are gap-matched, and the gap is 2 to 3 mm; the cleaning head clamping rod 5 and the cleaning head 6 are driven by the rotating rod 4 to perform a spiral rotation reciprocating motion along the threaded groove 9 of the inner wall of the heat exchanger. During the rotational motion, the cleaning head 6 cleans the tar and carbon deposits adhering to the inner wall 1 of the heat exchange tube, and at the same time, it applies disturbance to the raw coal gas, which can reduce the thickness of the boundary layer at the inner wall and enhance convective heat transfer.

[0020] See also Figures 3 to 8 In this embodiment, the front end of the cleaning head 6 is in the shape of an axe, and the front end surface thereof which is in clearance fit with the threaded groove on the inner wall of the heat exchange tube is composed of two triangular curved surfaces of different sizes, and the rear end connected with the cleaning head clamping rod is a semi-cylindrical structure. Three radial through holes are provided on the rear end of the cleaning head 6, and each radial through hole is connected to an axial soot blowing port 10 on the rear end of the cleaning head 6 near the front end, and each radial through hole is connected to a channel provided in the cleaning head clamping rod and the rotating rod, through which nitrogen or high-temperature compressed air or sulfuric acid solution can be introduced. The soot blowing port is usually cleaned with nitrogen to promptly clean the tar and carbon deposits cleaned by the axe-shaped cleaning head; high-temperature compressed air can be introduced during operation to burn the carbon deposits attached to the wall again at high temperature, thereby removing the carbon deposits; when the tar needs to be cleaned, sulfuric acid solution is added from the outside, and the sulfuric acid solution is sprayed onto the inner wall through the radial through holes set at the rear end of the cleaning head. The coal tar attached to the wall reacts chemically with the sulfuric acid to generate pyridine sulfate, which flows out of the riser with the raw coal gas or is physically removed by the cleaning head, thereby reducing the amount of coal tar attached to the wall.

[0021] When recovering waste heat, raw gas enters from the raw gas inlet at one end of the lower end cover 8, and water enters from the water inlet at the lower end of the heat exchange tube. The heat carried by the raw gas is transferred to the water through the inner wall 1 of the heat exchanger. After the water absorbs the heat, it generates steam or a steam-water mixture to complete the heat exchange. After the water exchanges heat, it is supplied to the user through the steam outlet at the upper end of the heat exchange tube, and the raw gas enters the chemical product recovery process from the raw gas outlet.

[0022] Coke oven raw gas contains a large amount of tar and dust. When entering the heat exchange tube for heat exchange, the tar is easy to condense on the inner wall of the heat exchange tube due to the decrease in temperature. Under the action of high temperature, part of the tar is carbonized to form carbon deposits, thereby affecting the waste heat recovery efficiency. The present invention utilizes an axe-shaped cleaning head to move in the groove on the inner wall of the heat exchange tube to automatically clean the tar and carbon deposits on the inner wall of the heat exchange tube, while increasing the airflow disturbance to the raw gas and reducing the thickness of the boundary layer at the inner wall, thereby improving the heat exchange efficiency of the heat exchanger.

Claims

1. A device for automatically cleaning tar and carbon deposits in heat exchange tubes for recovering waste heat from coke oven gas, the heat exchanger consisting of a shell and multiple rows and columns of heat exchange tubes; characterized in that: The inner wall of the heat exchange tube is a threaded groove structure. A rotating rod is installed on the center line of the heat exchange tube. The upper end of the rotating rod extends out of the upper end cover of the heat exchange tube and is connected to the driving device outside the shell. The lower end of the rotating rod is connected to a cleaning head clamping rod. Cleaning heads are installed at both ends of the cleaning head clamping rod. The cleaning head and the threaded groove of the inner wall of the heat exchange tube are in clearance fit. The cleaning head clamping rod and the cleaning head perform spiral rotation reciprocating motion along the threaded groove of the inner wall of the heat exchanger driven by the rotating rod. During the rotation motion, the cleaning head cleans the tar and carbon deposits adhering to the inner wall of the heat exchange tube and exerts disturbance on the raw gas at the same time. The front end of the cleaning head is in the shape of an axe, and the front end surface thereof which is in gap fit with the threaded groove on the inner wall of the heat exchange tube is composed of two triangular curved surfaces of different sizes, and the rear end thereof which is connected with the cleaning head clamping rod is a semi-cylindrical structure; A plurality of radial through holes are provided on the semi-cylindrical structure at the rear end of the cleaning head, each of which is connected to an axial soot blowing port on the rear end of the cleaning head close to the front end, and each of which is connected to a channel provided in the clamping rod and the rotating rod of the cleaning head, through which nitrogen or high-temperature compressed air or sulfuric acid solution can be introduced.

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