Online ash removal method for cross-flow heat exchanger

Abstract

The invention relates to an online ash cleaning method for a cross-flow heat exchanger, which comprises the following steps: 1) arranging a plurality of nozzles and high-pressure gas spray guns on one side of the cross-flow heat exchanger, and arranging an ash collecting structure on the other side of the cross-flow heat exchanger; 2) arranging an inlet one-way valve at the nozzle, and arranging an outlet one-way valve at the dust collecting structure; after the high-pressure gas spray gun is started, sprayed high-pressure gas is sprayed into the cross-flow heat exchanger through the inlet one-way valve, online dust removal is conducted on the interior of the cross-flow heat exchanger, the high-pressure gas carrying dust enters the dust collecting structure through the outlet one-way valve, and the dust in the dust collecting structure is removed regularly. And (3) the high-pressure gas spray gun is controlled by a control system of a functional unit where the cross-flow heat exchanger is located. Automatic ash removal can be achieved through the control system, and the purposes of accurate ash removal, energy saving and consumption reduction can be further achieved through a self-learning algorithm.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchanger ash cleaning, and particularly to an on-line ash cleaning method for a cross-flow heat exchanger. Background Art

[0002] Heat exchangers are used to achieve heat exchange between cold fluids and hot fluids and are widely used in fields such as petrochemical industry, electric power metallurgy, refrigeration and cryogenics, energy and power, aerospace, etc. According to statistics, in a general petrochemical enterprise, the investment in heat exchangers accounts for 40% - 50% of the total enterprise investment; in a thermal power plant, the investment in heat exchangers can reach about 70% of the total thermal power plant investment; in a refrigerator, the weight of the evaporator accounts for 30% - 40% of the total weight of the refrigerator, and its power consumption accounts for about 20% - 30% of the total power consumption.

[0003] A cross-flow heat exchanger refers to a heat exchanger in which two fluids flow perpendicular to each other and can be divided into two types: with fins and without fins. The application scenarios of cross-flow heat exchangers often have relatively harsh working conditions, generally with high temperature, a lot of dust, and strong corrosion, which directly affect their service life and operating efficiency. The ash accumulation in cross-flow heat exchangers is difficult to handle because cross-flow heat exchangers generally adopt a welded structure and many positions in the middle cannot be cleaned. Currently, for working conditions with not very high working temperatures, generally during maintenance, the cross-flow heat exchanger is cleaned offline by means such as vibration, acoustic waves, and high-pressure air gun blowing; for working conditions with high temperature and a lot of dust, the above methods are difficult to apply and mostly can only be replaced.

[0004] The invention patent CN201520926242.3 discloses an ash cleaning device for a tubular heat exchanger. Based on the designed heat transfer capacity and operating conditions of the heat exchanger and the heat transfer area of a single fin, it includes a plate-shaped ash cleaning knife and a chain. The height of the plate-shaped ash cleaning knife is less than the distance between adjacent rows of heat exchange tubes, and the plate-shaped ash cleaning knife can batch-clean the dust on the surface of the plate heat exchanger; the width of the chain is less than the distance between adjacent heat exchange tubes, and the chain collides with the heat exchange tubes to remove the dust adhering to the part of the heat exchange tube located between adjacent two heat exchange tubes. This method requires offline cleaning, has a high cleaning difficulty, and takes a long time.

[0005] The Chinese utility model patent with the application number CN201520926242.3 discloses an ash cleaning device for a tubular heat exchanger, which is used to clean the dust on the part of the heat exchange tube between two adjacent heat exchange tubes. It includes a plate-shaped ash cleaning knife and a chain. The height of the plate-shaped ash cleaning knife is less than the distance between two adjacent rows of heat exchange tubes, and the plate-shaped ash cleaning knife can batch clean the dust on the surface of the plate heat exchanger; the width of the chain is less than the distance between two adjacent heat exchange tubes, and the chain collides with the heat exchange tubes to remove the dust adhering to the part of the heat exchange tube between two adjacent heat exchange tubes. When using this method, the tubular heat exchanger must be taken offline for offline cleaning, and the cleaning efficiency is low and the time consumption is long.

[0006] The Chinese utility model patent with the application number CN201420621865.5 discloses an ash cleaning device for a finned tube heat exchanger, including: a pair of parallel tracks; a fixed frame, with a pair of tracks arranged on the fixed frame; a moving frame, which is provided with at least a pair of wheels and is movably arranged on the tracks through the wheels, and one of the wheels is a power output wheel; a brush shaft, which is rotatably arranged on the moving frame and is arranged parallel to the tracks; a cleaning brush, which is arranged on the brush shaft; a driving mechanism, which is connected to the moving frame and drives the moving frame to move along the tracks; and a steering transmission mechanism, which is arranged between the power output wheel and the brush shaft to drive the brush shaft to rotate when the power output wheel rolls along the tracks. The cleaning brush removes the dust adhering to the finned tubes through reciprocating motion and its own rotation. The structure of this device is relatively complex, and it can only achieve offline cleaning.

[0007] The Chinese utility model patent with the application number CN202321704164.3 discloses an ash cleaning device for a micro-negative pressure gas heat exchanger, which is used to solve the problems of dead angles in ash cleaning of heat exchange tubes of the current micro-negative pressure gas heat exchanger and inconvenient disassembly of the sealing flange; it includes a rear smoke box of the gas heat exchanger, with a rear smoke box tube plate on one side of the rear smoke box of the gas heat exchanger, and several ash cleaning devices are welded on one side of the rear smoke box tube plate. The ash cleaning device includes: a threaded tube, which is welded on one side of the rear smoke box tube plate, a quick-opening valve cover is threadedly connected to one end of the threaded tube, a sealing gasket is arranged between the threaded tube and the quick-opening valve cover, and a nut is welded on one side of the quick-opening valve cover. This device is an offline ash cleaning device, and its application field is relatively narrow. Summary of the Invention

[0008] The present invention provides an on-line ash cleaning method for a cross-flow heat exchanger. A spray nozzle is arranged on one side of the cross-flow heat exchanger, and a high-pressure gas spray gun is used for on-line ash cleaning. A dust collection structure is arranged on the other side of the cross-flow heat exchanger to collect the cleaned dust; automatic ash cleaning can be realized by using a control system, and the goals of accurate ash cleaning and energy saving and consumption reduction can be further achieved by using a self-learning algorithm.

[0009] To achieve the above object, the present invention is implemented by the following technical solutions:

[0010] An on-line dust cleaning method for a cross-flow heat exchanger includes the following processes:

[0011] 1) A plurality of nozzles and high-pressure gas spray guns are arranged on one side of the cross-flow heat exchanger, and a dust collecting structure is arranged on the other side of the cross-flow heat exchanger;

[0012] 2) An inlet check valve is arranged at the nozzle, and an outlet check valve is arranged at the dust collecting structure; after the high-pressure gas spray gun is started, the ejected high-pressure gas is sprayed into the cross-flow heat exchanger through the inlet check valve to perform on-line dust cleaning inside the cross-flow heat exchanger. The high-pressure gas carrying dust enters the dust collecting structure through the outlet check valve, and the dust in the dust collecting structure is cleaned regularly;

[0013] 3) The high-pressure gas spray gun is controlled by the control system of the functional unit where the cross-flow heat exchanger is located.

[0014] The cross-flow heat exchanger is an open heat exchanger, which is composed of heat exchange elements arranged in a flue; the nozzles are arranged on the flue wall on one side of the cross-flow heat exchanger, and the dust collecting structure arranged on the flue wall on the other side of the cross-flow heat exchanger is a dust collecting chamber.

[0015] The cross-flow heat exchanger is a closed heat exchanger, which is composed of a heat exchanger shell and heat exchange elements arranged inside the heat exchanger shell; the nozzles are arranged on one side of the heat exchanger shell, and the dust collecting structure arranged on the other side of the heat exchanger shell is a dust collecting box.

[0016] The high-pressure gas spray gun is composed of a vertical telescopic section, a horizontal telescopic section, a rotary joint, a nozzle and a switch control valve; one end of the vertical telescopic section is connected to a high-pressure gas source through a high-pressure gas delivery hose, and the other end of the vertical telescopic section is connected to one end of the horizontal telescopic section; both the vertical telescopic section and the horizontal telescopic section are telescopic structures; the other end of the horizontal telescopic section is connected to the nozzle through the rotary joint; the switch control valve is arranged on the horizontal telescopic section close to the rotary joint; the switch control valve is controlled by the control system,

[0017] The high-pressure gas spray gun is provided with rollers and a roller driving device, and the high-pressure gas spray gun moves along the spray gun slide rail under the drive of the roller driving device; the control end of the roller driving device is connected to the control system, and the moving position of the high-pressure gas spray gun is controlled by the control system.

[0018] The control system is provided with a self-learning model, which automatically controls the moving position, opening time and stopping time of the high-pressure gas spray gun according to the working conditions of the cross-flow heat exchanger.

[0019] The injection pressure of the high-pressure gas spray gun is 4 - 100 bar, and the injection gas flow rate is 0.14 - 0.42 Nm 3 / min.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] A spray nozzle is provided on one side of the cross-flow heat exchanger, and an online dust cleaning is carried out by using a high-pressure gas spray gun. A dust collection structure is provided on the other side of the cross-flow heat exchanger for collecting the cleaned dust. Automatic dust cleaning can be realized by using a control system, and the goals of accurate dust cleaning and energy saving and consumption reduction can be further achieved by using a self-learning algorithm. Description of the Drawings

[0022] Figure 1 is a schematic diagram of an online dust cleaning method for a cross-flow heat exchanger according to the present invention Figure 1 (Open heat exchanger).

[0023] Figure 2 is a schematic diagram of an online dust cleaning method for a cross-flow heat exchanger according to the present invention Figure 2 (Closed heat exchanger).

[0024] Figure 3 is a schematic structural diagram of the high-pressure gas spray gun according to the present invention

[0025] In the figure: 1. Flue; 2. Heat exchange element; 3. Inlet check valve; 4. High-pressure gas spray gun; 41. Vertical telescopic section; 42. Horizontal telescopic section; 43. Rotary joint; 44. Spray nozzle; 45. Switch control valve; 5. Spray gun slide rail; 6. Outlet check valve; 7. Ash collection chamber; 8. Heat exchanger housing; 9. Ash collection box Detailed Embodiments

[0026] The following further describes the detailed embodiments of the present invention with reference to the drawings:

[0027] As Figures 1 - 3 shown, an online dust cleaning method for a cross-flow heat exchanger according to the present invention includes the following processes:

[0028] 1) A plurality of spray nozzles and a high-pressure gas spray gun 4 are provided on one side of the cross-flow heat exchanger, and a dust collection structure is provided on the other side of the cross-flow heat exchanger;

[0029] 2) An inlet check valve 3 is provided at the spray nozzle, and an outlet check valve 6 is provided at the dust collection structure; after the high-pressure gas spray gun 4 is started, the ejected high-pressure gas is sprayed into the cross-flow heat exchanger through the inlet check valve 3 to perform online dust cleaning on the inside of the cross-flow heat exchanger. The high-pressure gas carrying dust enters the dust collection structure through the outlet check valve 6, and the dust in the dust collection structure is cleaned regularly;

[0030] 3) The high-pressure gas spray gun 4 is controlled by the control system of the functional unit where the cross-flow heat exchanger is located.

[0031] As Figure 1As shown, the cross-flow heat exchanger is an open heat exchanger, which consists of heat exchange elements 2 arranged in the flue 1; the nozzle is arranged on the flue wall on one side of the cross-flow heat exchanger, and the ash collection structure arranged on the flue wall on the other side of the cross-flow heat exchanger is the ash collection chamber 7.

[0032] As Figure 2 shown, the cross-flow heat exchanger is a closed heat exchanger, which consists of a heat exchanger housing 8 and heat exchange elements 2 arranged in the heat exchanger housing 8; the nozzle is arranged on one side of the heat exchanger housing 8, and the ash collection structure arranged on the other side of the heat exchanger housing 8 is the ash collection box 9.

[0033] As Figure 3 shown, the high-pressure gas spray gun 4 consists of a vertical telescopic section 41, a horizontal telescopic section 42, a rotary joint 43, a nozzle 44 and a switch control valve 45; one end of the vertical telescopic section 41 is connected to the high-pressure gas source through a high-pressure gas delivery hose, and the other end of the vertical telescopic section 41 is connected to one end of the horizontal telescopic section 42; both the vertical telescopic section 41 and the horizontal telescopic section 42 are telescopic structures; the other end of the horizontal telescopic section 42 is connected to the nozzle 44 through the rotary joint 43; the switch control valve 45 is arranged on the horizontal telescopic section 42 close to the rotary joint 43.

[0034] The high-pressure gas spray gun 4 is provided with rollers and a roller driving device, and the high-pressure gas spray gun 4 moves along the spray gun slide rail 5 under the drive of the roller driving device; the control end of the roller driving device is connected to the control system, and the moving position of the high-pressure gas spray gun 4 is controlled by the control system.

[0035] The control system is provided with a self-learning model, and automatically controls the moving position, opening time and stopping time of the high-pressure gas spray gun 4 according to the working conditions of the cross-flow heat exchanger.

[0036] The injection pressure of the high-pressure gas spray gun is 4 - 100 bar, and the injection gas flow rate is 0.14 - 0.42 Nm 3 / min.

[0037] The on-line ash cleaning method for a cross-flow heat exchanger according to the present invention is applicable to most existing cross-flow heat exchangers. The cross-flow heat exchanger is divided into an open heat exchanger and a closed heat exchanger according to the structural form. The open heat exchanger means that the heat exchange elements 2 are directly placed in the heat exchange space (such as the flue 1), and the closed heat exchanger means that the heat exchange elements 2 are placed in the heat exchanger housing 8.

[0038] A nozzle is arranged on one side of the cross-flow heat exchanger for injecting high-pressure gas into the cross-flow heat exchanger through the high-pressure gas spray gun 4. The gas source of the high-pressure gas spray gun 4 can be high-pressure air or high-pressure inert gas. For example, high-pressure inert gas can be injected when there are flammable substances in the flue 1.

[0039] The nozzle is provided on the side wall of the flue 1 or the side wall of the heat exchanger housing 8. The ash collection structure can be an ash collection chamber 7 provided on one side of the flue 1 or an ash collection box 9 welded to the outside of the heat exchanger housing 8.

[0040] During the operation of the production system, the ash cleaning operation of the cross-flow heat exchanger can be switched between manual mode and automatic mode. In the manual mode, the operator selects the blowing position and blowing time of the high-pressure gas spray gun 4; in the automatic mode, the control system automatically controls the blowing position, blowing time, and blowing interval of the high-pressure gas spray gun 4, and can further perform automatic control according to different production conditions through a self-learning algorithm to perform online ash cleaning on the cross-flow heat exchanger.

[0041] The structure of the high-pressure gas spray gun 4 is as Figure 3 shown. Each high-pressure gas spray gun 4 is provided with a control switch valve 45 for turning on / off the high-pressure gas spray gun 4 and adjusting the gas flow rate. Each high-pressure gas spray gun 4 can correspond to one or more nozzles, and the number of high-pressure gas spray guns 4 is determined according to the specifications and structural forms of the cross-flow heat exchanger.

[0042] The vertical telescopic section 41 and the horizontal telescopic section 42 of the high-pressure gas spray gun 4 can be extended during use and retracted when not in use, which is convenient for the movement and maintenance of the high-pressure gas spray gun 4. The rotary joint 43 of the high-pressure gas spray gun 4 is used to adjust the angle of the nozzle 44, increase the blowing area, and enable effective ash cleaning of all parts of the cross-flow heat exchanger. High-pressure gas is ejected from the nozzle 44 of the high-pressure gas spray gun 4.

[0043] Select the opening position of the nozzle according to the specifications and structural forms of the cross-flow heat exchanger, and install an inlet check valve 3 with an area larger than the nozzle at the opening position. Similarly, select the opening position of the gas outlet according to the specifications and structural forms of the cross-flow heat exchanger, and install an outlet check valve 6 with an area larger than the gas outlet at the opening position. The inlet check valve 3 and the outlet check valve 6 can be selected according to the temperature and working conditions of the cross-flow heat exchanger, as long as unidirectional air flow can be achieved to prevent the reverse flow of air. Preferably, both the inlet check valve 3 and the outlet check valve 6 adopt a baffle structure. The baffle can rotate through the connecting shaft at the upper end and can be opened in the gas jet direction under the action of high-pressure gas; when the high-pressure gas stops jetting, the baffle blocks the nozzle and the gas outlet under the action of gravity to prevent the internal gas from escaping.

[0044] The online ash cleaning method for a cross-flow heat exchanger according to the present invention solves the problems of the existing cross-flow heat exchanger being unable to perform online ash cleaning, the ash cleaning operation being complex, and the cleaning being incomplete. By using a high-pressure gas spray gun, different positions of the cross-flow heat exchanger can be blown to prevent dust accumulation. By setting a self-learning program, the blowing time, blowing position, and blowing frequency can be automatically adjusted according to different working conditions, which is an energy-saving, efficient, and simple online ash cleaning method for cross-flow heat exchangers.

[0045] Adjust the operating parameters of the high-pressure gas spray gun according to the operating pressure of the cross-flow heat exchanger.

[0046] As mentioned above, the above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent replacements or changes should be covered within the protection scope of the present invention.

Claims

1. An on-line dust cleaning method for a cross-flow heat exchanger, characterized in that, It includes the following processes: 1) Multiple nozzles and a high-pressure gas spray gun are provided on one side of the cross-flow heat exchanger, and an ash collection structure is provided on the other side of the cross-flow heat exchanger; 2) An inlet check valve is provided at the nozzle, and an outlet check valve is provided at the ash collection structure; After the high-pressure gas spray gun is started, the sprayed high-pressure gas is sprayed into the cross-flow heat exchanger through the inlet check valve to perform on-line ash cleaning inside the cross-flow heat exchanger. The high-pressure gas carrying dust enters the ash collection structure through the outlet check valve, and the dust in the ash collection structure is regularly cleaned; 3) The high-pressure gas spray gun is controlled by the control system of the functional unit where the cross-flow heat exchanger is located.

2. The online dust cleaning method of a cross-flow heat exchanger according to claim 1, characterized in that The cross-flow heat exchanger is an open heat exchanger composed of heat exchange elements arranged in the flue. The nozzle is arranged on the flue wall on one side of the cross-flow heat exchanger, and the ash collection structure arranged on the flue wall on the other side of the cross-flow heat exchanger is an ash collection chamber.

3. A method for online dust cleaning of a cross-flow heat exchanger according to claim 1, characterized in that, The cross-flow heat exchanger is a closed heat exchanger composed of a heat exchanger housing and heat exchange elements arranged inside the heat exchanger housing. The nozzle is arranged on one side of the heat exchanger housing, and the ash collection structure arranged on the other side of the heat exchanger housing is an ash collection box.

4. The online dust cleaning method of a cross-flow heat exchanger according to claim 1, characterized in that The high-pressure gas spray gun is composed of a vertical telescopic section, a horizontal telescopic section, a rotary joint, a nozzle and a switch control valve. One end of the vertical telescopic section is connected to a high-pressure gas source through a high-pressure gas delivery hose, and the other end of the vertical telescopic section is connected to one end of the horizontal telescopic section. Both the vertical telescopic section and the horizontal telescopic section are telescopic structures. The other end of the horizontal telescopic section is connected to the nozzle through the rotary joint. The switch control valve is arranged on the horizontal telescopic section near the rotary joint. The switch control valve is controlled by the control system.

5. A method for online dust cleaning of a cross-flow heat exchanger according to claim 1, characterized in that, The high-pressure gas spray gun is provided with rollers and a roller driving device, and the high-pressure gas spray gun moves along the spray gun slide rail under the drive of the roller driving device. The control end of the roller driving device is connected to the control system, and the moving position of the high-pressure gas spray gun is controlled by the control system.

6. The online soot cleaning method of a cross-flow heat exchanger according to claim 1, characterized in that, The control system is provided with a self-learning model to automatically control the moving position, opening time and stopping time of the high-pressure gas spray gun according to the working conditions of the cross-flow heat exchanger.

7. A method for online dust cleaning of a cross-flow heat exchanger according to claim 1, characterized in that, The injection pressure of the high-pressure gas spray gun is 4 to 100 bar, and the injection gas flow rate is 0.14 to 0.42 Nm 3 / min.

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