Method for preventing blockage failure of heat exchanger of blast furnace hot blast stove

Abstract

The invention discloses a method for preventing a heat exchanger of a blast furnace hot blast stove from being blocked and losing efficacy. A flue gas inlet, a high-temperature section heat exchange box, a low-temperature section heat exchange box and a dirt settling box are adjacently arranged in the vertical direction; high-temperature flue gas enters from the flue gas inlet in the vertical direction, sequentially flows through the high-temperature section heat exchange box, the low-temperature section heat exchange box and the dirt settling cavity and then flows out from the flue gas outlet, and the flue gas vertically flows in the flue gas inlet from top to bottom, so that the flowing resistance of the flue gas can be reduced; the heat exchanger is provided with the dirt settling box, blockage substances generated in the circulation process of the smoke can fall into the dirt settling box due to the gravity effect, deposition of dust in the smoke and corrosion products on the heat exchange elements on the heat exchange elements is greatly reduced, meanwhile, the flushing device is arranged, the possibility that the heat exchanger is blocked is reduced, and the heat exchange efficiency of the heat exchanger is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of heat exchange equipment, and in particular, relates to a method for preventing a blast furnace hot blast stove heat exchanger from being blocked and failing. Background Art

[0002] During the steel production and smelting process, waste heat is mainly concentrated in the blast furnace ironmaking process, and waste heat resources account for more than 40% of the entire steel production. If it can be fully recycled and utilized, the energy consumption of the ironmaking process can be reduced by about 4% to 5%. Heat exchangers are the main equipment for waste heat recovery and energy saving. They transfer the heat generated in industrial production from a higher temperature fluid to a lower temperature fluid, that is, recover the heat through heat transfer and reuse it.

[0003] At present, the flue gas flows in the heat exchanger basically in the horizontal direction and the flow rate is relatively slow. The acidic gas in the flue gas will corrode the heat exchange metal elements. The corrosion products and dust particles in the flue gas are easily deposited on the heat exchange elements and in the bottom gaps between the heat exchange elements, blocking the heat exchange channels between the heat exchange elements, reducing the effective cross-sectional area of ​​the flue gas flowing in the heat exchanger, and seriously hindering the heat transfer between the flue gas and the preheating medium, resulting in a significant decrease in the heat exchange efficiency of the heat exchanger. In summary, there is an urgent need for a method to prevent the blast furnace hot blast stove heat exchanger from clogging and failure. Summary of the invention

[0004] The embodiment of the present application provides a method for preventing blast furnace hot blast stove heat exchanger from clogging and failure, which can reduce the deposition of dust particles and corrosion products on the heat exchange elements, reduce the possibility of heat exchanger clogging, and improve the heat exchange efficiency of the heat exchanger.

[0005] In a first aspect, an embodiment of the present application provides a method for preventing a blast furnace hot blast furnace heat exchanger from being blocked and failing. The blast furnace hot blast furnace heat exchanger comprises a flue gas inlet, a heat exchange box, a waste settling box, a preheating medium reversing chamber, a preheating medium inlet, a preheating medium outlet and a flue gas outlet. The heat exchange box comprises a high-temperature section heat exchange box and a low-temperature section heat exchange box. The low-temperature section heat exchange box is provided with a preheating medium inlet, and the high-temperature section heat exchange box is provided with a preheating medium outlet. The method comprises: arranging the flue gas inlet, the high-temperature section heat exchange box, the low-temperature section heat exchange box and the waste settling box adjacent to each other in a vertical direction; arranging the preheating medium reversing chamber on one side of the heat exchange box in a horizontal direction; the flue gas enters from the flue gas inlet in a vertical direction, passes through the high-temperature section heat exchange box, the low-temperature section heat exchange box and the waste settling box in sequence, and flows out from the flue gas outlet; the preheating medium enters from the preheating medium inlet in a horizontal direction, passes through the low-temperature section heat exchange box, the preheating medium reversing chamber and the high-temperature section heat exchange box in sequence, and flows out from the preheating medium outlet.

[0006] In the embodiment of the present application, the flue gas inlet, the high-temperature section heat exchange box, the low-temperature section heat exchange box and the dirt settling box are arranged adjacent to each other in the vertical direction. The flue gas can flow vertically from top to bottom in the high-temperature section heat exchange box and the low-temperature section heat exchange box under the action of gravity, thereby reducing the flow resistance of the flue gas; after completing the heat exchange of the preheating medium in the high-temperature section heat exchange box and the low-temperature section heat exchange box, the flue gas enters the dirt settling box at the bottom of the low-temperature section heat exchange box and turns therein, and finally flows out from the flue gas outlet, ensuring that the sediment and corrosion products generated by the flue gas during the circulation process can fall into the dirt settling box due to the action of gravity, thereby greatly reducing the deposition of dust particles and corrosion products in the flue gas on the heat exchange elements, reducing the possibility of blockage of the heat exchanger, and improving the heat exchange efficiency of the heat exchanger.

[0007] According to an embodiment of the first aspect of the present application, the method further includes: disposing a sewage valve at the bottom of the sewage settling tank.

[0008] The embodiment of the present application provides a drain valve to discharge dust particles entrained in the flue gas and corrosion products on the heat exchange element out of the heat exchanger, thereby increasing the accommodation space of the waste settling box.

[0009] According to an embodiment of the first aspect of the present application, a cleaning spray water pipe is provided in the smoke inlet.

[0010] The embodiment of the present application arranges a cleaning spray water pipe in the flue gas inlet. When the dust and corrosion products adhering to the heat exchange elements reach a certain thickness and affect the heat exchange effect of the heat exchanger, water can be sprayed into the high-temperature section heat exchanger box during a wind down maintenance or in a regular cleaning manner. The water can dissolve most of the corrosion products on the heat exchange elements, and bring the water-insoluble dust and adherent particles into the dirt settling box under the low-temperature section heat exchanger box. The corrosion products and entrained adherent particles can be discharged from the heat exchanger by opening the drain valve under the dirt settling box.

[0011] According to an embodiment of the first aspect of the present application, the high temperature section heat exchange box includes a tubular heat exchanger or a plate heat exchanger.

[0012] According to an embodiment of the first aspect of the present application, the low-temperature section heat exchange box includes a tubular heat exchanger or a plate heat exchanger.

[0013] According to an embodiment of the first aspect of the present application, the tubular heat exchanger is selected from one of a shell and tube heat exchanger, a wound tube heat exchanger, a serpentine heat exchanger and a shell and tube heat exchanger; the plate heat exchanger is selected from one of a plate and frame heat exchanger, a plate and shell heat exchanger, a spiral plate heat exchanger and an umbrella plate heat exchanger.

[0014] The tubular heat exchanger has a large heat transfer area, which improves the heat transfer efficiency between the flue gas and the preheating medium. The tubular heat exchanger has a compact structure, which reduces the space occupied by the heat exchanger in the heat exchange box. The plate heat exchanger can adapt to different heat exchange requirements by changing the plate arrangement or replacing different numbers of plates.

[0015] According to an embodiment of the first aspect of the present application, the shape of the sewage settling tank is a cone that is wide at the top and narrow at the bottom.

[0016] The embodiment of the present application designs the shape of the waste settling box to be a cone that is wide at the top and narrow at the bottom, which can not only store waste, but also helps to gather the waste at the bottom of the waste settling box. When the blast furnace hot blast stove has an opportunity to be shut down for maintenance, the drain valve can be opened to discharge the waste in the waste settling box.

[0017] According to the embodiment of the first aspect of the present application, when the heat exchanger of the blast furnace hot blast stove stops operating, the cleaning spray water pipe is used to regularly spray water to clean the heat exchange box.

[0018] According to the embodiment of the first aspect of the present application, the diameter of the flue pipe at the flue gas inlet gradually increases along the direction from the flue gas inlet to the high-temperature section heat exchange box.

[0019] In the embodiment of the present application, the flue pipe diameter at the flue gas inlet gradually increases along the direction of the flue gas inlet toward the high-temperature section heat exchanger box, which can increase the contact area and time between the flue gas and the preheating medium, thereby improving the heat transfer efficiency; the design of the expansion section can also smoothly guide the flue gas into the high-temperature section heat exchanger box, reduce the resistance of the flue gas when entering the heat exchanger, thereby reducing the pressure loss, helping to maintain the overall efficiency of the system and reduce energy consumption; in addition, in the flue gas heat exchanger, the flue gas usually contains particulate matter and corrosive substances. The design of the expansion section can reduce the deposition and accumulation of these particulate matter inside the heat exchanger, thereby extending the service life of the heat exchanger; the design of the expansion section also helps to reduce the direct impact of the flue gas on the heat exchanger and protect the structural integrity of the heat exchanger.

[0020] According to the embodiment of the first aspect of the present application, the flue diameter of the preheating medium inlet gradually increases along the direction from the preheating medium inlet to the low-temperature section heat exchange box; the flue diameter of the preheating medium outlet gradually increases along the direction from the preheating medium outlet to the high-temperature section heat exchange box.

[0021] The embodiment of the present application increases the contact area and time between the preheating medium and the flue gas by designing the flue pipe diameter at the preheating medium inlet to gradually increase along the direction from the preheating medium inlet to the low-temperature section heat exchanger box, thereby improving the heat transfer efficiency; the design of the expansion section can also smoothly guide the preheating medium into the low-temperature section heat exchanger box, reduce the resistance of the preheating medium when entering the heat exchanger, thereby reducing pressure loss, helping to maintain the overall efficiency of the system and reduce energy consumption; the design of the expansion section also helps to reduce the direct impact of the preheating medium on the heat exchanger and protect the structural integrity of the heat exchanger.

[0022] The method for preventing blast furnace hot blast furnace heat exchanger from clogging and failure by adopting the embodiment of the present application can greatly reduce the deposition of dust in the flue gas and corrosion products on the heat exchange elements when the heat exchanger is working normally, so that the dust mainly falls into the dirt settling box, thereby effectively reducing the possibility of clogging of the heat exchanger; the corrosion products and dust adhering to the heat exchange elements can be conveniently cleaned by water flushing during maintenance opportunities or by regular cleaning, thereby ensuring that the heat exchange effect of the heat exchanger will not be greatly attenuated; it is more in line with the natural flow direction of cold and hot fluids, thereby reducing the fluid flow resistance in the heat exchanger; the service life of the heat exchanger can be greatly extended, creating better conditions for energy saving and consumption reduction in blast furnaces; compared with traditional heat exchangers, it occupies less space. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 It is a structural schematic diagram of a blast furnace hot blast stove heat exchanger of the related art;

[0025] Figure 2 This is a schematic structural diagram of a blast furnace hot blast stove heat exchanger according to an embodiment of the present application;

[0026] Among them, the solid arrows represent the flow path of the flue gas in the blast furnace hot blast stove heat exchanger, and the hollow arrows represent the flow path of the preheating medium in the blast furnace hot blast stove heat exchanger.

[0027] Reference numerals:

[0028] 1. Flue gas inlet; 2. High temperature section heat exchange box; 3. Low temperature section heat exchange box; 4. Flue gas outlet;

[0029] 5. Preheating medium inlet; 6. Preheating medium reversing chamber; 7. Preheating medium outlet;

[0030] 1′, flue gas inlet; 2′, high temperature section heat exchange box; 3′, low temperature section heat exchange box; 4′, dirt settling box; 5′, flue gas outlet; 6′, preheating medium inlet; 7′, preheating medium reversing chamber; 8′, preheating medium outlet; 9′, cleaning spray water pipe; 10′, drain valve; 11′, heat exchange box. DETAILED DESCRIPTION

[0031] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating examples of the present application. In the accompanying drawings and the following description, at least some of the known structures and technologies are not shown to avoid unnecessary ambiguity in the present application; and, for clarity, the size of some structures may be exaggerated. In addition, the features, structures or characteristics described below may be combined in one or more embodiments in any suitable manner.

[0032] It should be noted that, in this application, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0033] Figure 1 This is a schematic diagram of the working principle of a traditional blast furnace hot blast stove plate heat exchanger. Figure 1 In the traditional blast furnace hot blast stove plate heat exchanger, the flue gas introduced from the main flue basically flows in the horizontal direction. The flue gas enters the high temperature section heat exchange box 2 through the flue gas inlet 1 with an expansion section, then enters the low temperature section heat exchange box 3 in the horizontal direction, and finally flows through the flue gas outlet 4 with a contraction section and returns to the main flue; the preheating medium (coal gas or combustion air, etc.) mainly flows in the vertical direction in the heat exchanger. The preheating medium is usually introduced to the top of the heat exchanger, flows from top to bottom through the preheating medium inlet 5 with an expansion section and enters the low temperature section heat exchange box 3, then turns in the preheating medium reversing chamber 6, and then flows from bottom to top into the high temperature section heat exchange box 2, and finally flows through the preheating medium outlet 7 with a contraction section and returns to the preheating medium main pipeline; the flue gas channel and the preheating medium channel in the heat exchange box are separated from each other; an inspection hole is usually opened on the expansion section or contraction section of the flue gas and preheating medium inlet and outlet to check the blockage and corrosion of the heat exchange box.

[0034] This traditional type of preheater is very prone to blockage in the flue gas channel at the low temperature section. This is mainly due to the fact that the flue gas contains a certain amount of dust particles, and the acidic gas in the flue gas will also corrode the heat exchange metal elements. Since the flow rate of the flue gas is relatively slow, the dust in the flue gas and the corrosion products of the heat exchange elements are very easy to deposit on the heat exchange elements and the bottom of the gaps between the heat exchange elements in the horizontal flow of the flue gas in the traditional heat exchanger, and it is very difficult to clean. In this way, on the one hand, the adhesion deposited on the heat exchange element seriously hinders the heat transfer between the flue gas and the preheating medium, and on the other hand, it causes the effective cross-sectional area of ​​the flue gas to decrease rapidly, and finally the heat exchange effect of the heat exchanger is quickly attenuated. In particular, the heat exchange effect of the air preheater is often only about 30% of that of the initial operation after 3-4 years of operation. However, since the preheating medium has a fast flow rate and flows vertically in the heat exchange box, there is basically no blockage in its flow channel.

[0035] The applicant found that in the traditional blast furnace hot blast stove plate heat exchanger, the flue gas introduced from the main flue basically flows in the horizontal direction. The dust in the flue gas and the corrosion products of the heat exchange elements are very easy to deposit on the heat exchange elements and at the bottom of the gaps between the heat exchange elements, making them difficult to clean. The adhesion deposited on the heat exchange elements will block the heat exchange channels between the heat exchange elements, which not only seriously hinders the heat transfer between the flue gas and the preheating medium, but also rapidly reduces the effective cross-sectional area of ​​the flue gas circulation, ultimately resulting in a significant decrease in the heat exchange effect of the heat exchanger.

[0036] In order to solve the problems of the prior art, the applicant has proposed a method to prevent the heat exchanger of the blast furnace hot blast stove from being blocked and failing. Specifically, the heat exchanger is designed with the high-temperature section heat exchanger box on the top and the low-temperature section heat exchanger box on the bottom, and they are stacked up and down. The flue gas flows vertically from top to bottom in the heat exchanger box, while the preheating medium enters the low-temperature section heat exchanger box at the bottom horizontally, and then turns to enter the high-temperature section heat exchanger box at the top to complete its heating process. A dirt settling box with a drain valve is designed below the low-temperature section heat exchanger box, and most of the blockages generated in the flue gas channel can fall into it under the action of gravity. At the same time, a cleaning spray water pipe is provided in the flue gas inlet, and the corrosion products and adherent particles on the heat exchange element can be discharged from the heat exchanger by spraying water.

[0037] Figure 2 This is a schematic diagram of the working principle of the blast furnace hot blast stove heat exchanger according to an embodiment of the present application.

[0038] The present application embodiment provides a method for preventing the blast furnace hot blast stove heat exchanger from clogging and failing. Figure 2Specifically, in the blast furnace hot blast stove heat exchanger of the embodiment of the present application, the high temperature section heat exchange box 2' and the low temperature section heat exchange box 3' are combined in an up-and-down stacking manner, with the high temperature section heat exchange box 2' on top and the low temperature section heat exchange box 3' on the bottom, instead of being arranged horizontally side by side like a traditional heat exchanger;

[0039] The flue gas flows vertically from top to bottom in the heat exchange box 11' of the heat exchanger, rather than flowing horizontally as in a conventional heat exchanger;

[0040] The high-temperature flue gas from the main flue is introduced into the top of the heat exchanger, and enters the high-temperature section heat exchange box 2' through the flue gas inlet 1' with an expansion section, where it completes the heat exchange with the preheating medium and heats the preheating medium to the final temperature;

[0041] After completing the high-temperature heat exchange, the flue gas enters the low-temperature heat exchange box 3' from top to bottom, where it completes the heat exchange with the preheating medium and performs preliminary heating on the preheating medium;

[0042] After completing the low-temperature heat exchange, the flue gas enters the conical-shaped dirt settling box 4' at the bottom of the heat exchanger and turns therein, flows out in a horizontal direction through the flue gas outlet 5' connected to the dirt settling box 4', and then returns to the main flue;

[0043] The preheating medium enters the low temperature section heat exchange box 3' horizontally through the preheating medium inlet 6' with an expansion section, and enters the preheating medium reversing chamber 7' after being preliminarily heated by the flue gas;

[0044] After the preliminary heating, the preheating medium is turned in the preheating medium reversing chamber 7' and enters the high temperature section heat exchange box 2' again from the horizontal direction to complete the final heating;

[0045] The heated preheating medium flows out horizontally to a desired position through the preheating medium outlet 8' with a contraction section;

[0046] During the operation of the preheater, since the flow direction of the flue gas in the preheater is consistent with the direction of gravity, most of the dust carried in the flowing flue gas and the molten sulfuric acid salts produced by the corrosion of the heat exchange elements by the flue gas will fall into the dirt settling box 4' at the bottom of the heat exchanger under the action of gravity, and only a small part will still adhere to the heat exchange elements. The dirt settling box 4' has a large space to accommodate these settled dust and corrosion products without causing serious blockage. A drain valve 10' is provided at the bottom of the dirt settling box 4'. When the blast furnace has an opportunity to stop for maintenance, the drain valve 10' can be opened to discharge the dirt in the dirt settling box 4';

[0047] When the dust and corrosion products adhering to the heat exchange elements reach a certain thickness and affect the heat exchange effect of the heat exchanger, you can use the maintenance opportunity or regular cleaning method to use the cleaning spray water pipe 9' installed in the flue gas inlet expansion section and extending into the flue gas inlet 1' to spray water into the high-temperature section heat exchange box 2'. The water will dissolve most of the corrosion products on the heat exchange elements and bring the water-insoluble dust and adherent particles into the dirt settling box 4' under the low-temperature section heat exchange box 3'. They will be discharged from the heat exchanger by opening the drain valve 10' under the dirt settling box 4'.

Claims

1. A method for preventing a blast furnace hot blast furnace heat exchanger from being blocked and failing, the blast furnace hot blast furnace heat exchanger comprising a flue gas inlet, a heat exchange box, a dirt settling box, a preheating medium reversing chamber, a preheating medium inlet, a preheating medium outlet and a flue gas outlet, the heat exchange box comprising a high temperature section heat exchange box and a low temperature section heat exchange box, the low temperature section heat exchange box is provided with the preheating medium inlet, the high temperature section heat exchange box is provided with the preheating medium outlet, characterized in that: include: The flue gas inlet, the high temperature section heat exchange box, the low temperature section heat exchange box and the waste settling box are arranged adjacent to each other in the vertical direction; The preheating medium reversing chamber is arranged transversely on one side of the heat exchange box; The flue gas enters from the flue gas inlet along the vertical direction, passes through the high temperature section heat exchange box, the low temperature section heat exchange box and the waste settling box in sequence, and flows out from the flue gas outlet; The preheating medium enters from the preheating medium inlet in a horizontal direction, passes through the low-temperature section heat exchange box, the preheating medium reversing chamber and the high-temperature section heat exchange box in sequence, and flows out from the preheating medium outlet.

2. The method according to claim 1, characterized in that The method further includes: arranging a sewage valve at the bottom of the sewage settling tank.

3. The method according to claim 1, characterized in that A cleaning spray water pipe is arranged in the smoke inlet.

4. The method according to claim 1, characterized in that: The high temperature section heat exchange box includes a tubular heat exchanger or a plate heat exchanger.

5. The method according to claim 1, characterized in that The low temperature section heat exchange box includes a tubular heat exchanger or a plate heat exchanger.

6. The method according to any one of claims 4 or 5, characterized in that: The tubular heat exchanger is selected from one of a shell and tube heat exchanger, a wound tube heat exchanger, a coiled tube heat exchanger and a double-tube heat exchanger; The plate heat exchanger is selected from one of a plate-frame heat exchanger, a plate-shell heat exchanger, a spiral plate heat exchanger and an umbrella plate heat exchanger.

7. The method according to claim 1, characterized in that The shape of the sewage settling box is a cone that is wide at the top and narrow at the bottom.

8. The method according to claim 3, characterized in that When the blast furnace hot blast stove heat exchanger stops operating, the cleaning spray water pipe regularly sprays water to clean the heat exchange box.

9. The method according to claim 1, characterized in that: The flue pipe diameter of the flue gas inlet gradually increases along the direction from the flue gas inlet to the high temperature section heat exchange box.

10. The method according to claim 1, characterized in that The flue pipe diameter of the preheating medium inlet gradually increases along the direction from the preheating medium inlet to the low temperature section heat exchange box; The flue pipe diameter of the preheating medium outlet gradually increases along the direction from the preheating medium outlet to the high-temperature section heat exchange box.

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