Online vibration ash removal method for heat exchanger

Abstract

The invention relates to an on-line vibration ash removal method for a heat exchanger. A vibration ash removal device is adopted for carrying out on-line ash removal on the heat exchanger. The vibration ash removal device is composed of a moving trolley, a lifting mechanism, a platform plate, a knocker and a vibrator. The moving trolley is arranged on the track and can horizontally and longitudinally move along the track; the platform plate is arranged on the moving trolley through a lifting mechanism; the knocker and the vibrator are arranged on the platform plate; a plurality of rows of ash removal openings are formed in the side wall of the flue where the heat exchanger is located, the control system judges whether the ash removal thickness on the surface of the heat exchanger reaches the set ash removal thickness or not according to real-time temperature measurement data of a thermocouple, and when the set ash removal thickness is reached, the control system controls the vibration ash removal device to remove ash. The heat exchange efficiency of the heat exchanger is guaranteed, and the service life of the heat exchanger is prolonged.

Description

Technical Field

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

[0002] A heating furnace is a commonly used heating device in the metallurgical industry, mainly used for heating steel billets. Since about 30% of the waste heat of the heating furnace is carried in the flue gas of the heating furnace, generally a heat exchanger is used to recover the waste heat of the flue gas to improve the energy utilization rate. The heat exchanger for recovering the waste heat of the heating furnace flue gas is arranged in the flue, and the working environment is harsh, the flue gas temperature is relatively high and the dust is large. At high temperatures, the dust in the flue gas melts and adheres to the surface of the heat exchanger. As the dust accumulates continuously, the heat transfer efficiency of the heat exchanger is reduced, and the service life of the heat exchanger is seriously affected.

[0003] The ash accumulation of the heat exchanger arranged in the flue is usually difficult to handle because the viscosity of the dust is very high at high temperatures, and as the thickness of the dust accumulation increases, the cleaning difficulty also increases. And the heat exchanger generally adopts a welded structure, and many positions in the middle cannot be cleaned, resulting in that the conventional ash cleaning methods cannot achieve good ash cleaning effects. At present, most of the commonly used heat exchanger ash cleaning methods are applicable to occasions where the temperature is not very high. Generally, when overhauling, the heat exchanger is cleaned offline by means of vibration, acoustic wave and high-pressure air gun blowing, etc. For the situation of high temperature and a large amount of dust, the above methods are difficult to play the expected role, and can only be replaced when the efficiency of the heat exchanger is reduced to a certain extent.

[0004] The Chinese utility model patent with the application number CN201520926242.3 discloses an "ash cleaning device for a tubular heat exchanger" to realize the cleaning of the dust on the part of the heat exchange tube between adjacent two heat exchange tubes, including 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 two 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 two heat exchange tubes, and the chain collides with the heat exchange tubes to remove the dust adhering to the part of the heat exchange tubes between adjacent two 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.

[0005] The Chinese utility model patent with the application number CN201420621865.5 discloses an ash cleaning device for finned tube heat exchangers, which includes: a pair of parallel tracks; a fixed frame on which the pair of tracks are arranged; a moving frame provided with at least a pair of wheels and movably arranged on the tracks through the wheels, and one of the wheels is a power output wheel; a brush shaft rotatably arranged on the moving frame and parallel to the tracks; a cleaning brush arranged on the brush shaft; a driving mechanism connected to the moving frame to drive the moving frame to move along the tracks; and a steering transmission mechanism 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. This device has a relatively complex structure and can only achieve offline cleaning.

[0006] The Chinese utility model patent with the application number CN202321704164.3 discloses a micro-negative pressure gas heat exchanger ash cleaning device, which is used to solve the problems of dead corners in ash cleaning of heat exchange tubes of micro-negative pressure gas heat exchangers and inconvenient disassembly of sealing flanges; it includes a rear smoke box of the gas heat exchanger, one side of the rear smoke box of the gas heat exchanger is provided with a rear smoke box tube sheet, and a number of ash cleaning devices are welded on one side of the rear smoke box tube sheet. The ash cleaning device includes: a threaded tube welded on one side of the rear smoke box tube sheet, a quick-opening valve cover 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 has a relatively narrow application field. Summary of the Invention

[0007] The present invention provides an online vibration ash cleaning method for heat exchangers. Multiple rows of ash cleaning openings are arranged on the side wall of the flue where the heat exchanger is located. The control system judges whether the ash accumulation thickness on the heat exchanger surface reaches the set ash cleaning thickness through the real-time temperature measurement data of the thermocouple. When the set ash cleaning thickness is reached, the control system controls the vibration ash cleaning device to carry out ash cleaning, which can effectively extend the overhaul period of the heat exchanger, reduce production costs, ensure the heat exchange efficiency of the heat exchanger, and extend the service life of the heat exchanger.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] An online vibration ash cleaning method for heat exchangers includes the following processes:

[0010] 1) The heat exchanger is arranged in the flue of the heating furnace and consists of multiple rows of heat exchange elements; multiple rows of ash cleaning openings are arranged on one side of the flue corresponding to the installation position of the heat exchanger; the ash cleaning openings are composed of multiple through holes arranged at intervals, and each through hole is closed by a baffle arranged in the flue.

[0011] 2) An on-line soot cleaning device is adopted to clean the heat exchanger; the on-line soot cleaning device consists of a mobile trolley, a lifting mechanism, a platform plate, a knocker and a vibrator; the mobile trolley is arranged on the track and can move horizontally and vertically along the track; the platform plate is arranged on the mobile trolley through the lifting mechanism; both the knocker and the vibrator are arranged on the platform plate;

[0012] 3) Temperature measuring devices for the tube wall are arranged at multiple parts of the heat exchanger. The temperature measuring devices for the tube wall send the measured temperature data in real time to the control system. The control system calculates the difference between the theoretical tube wall temperature and the measured tube wall temperature. When the difference is greater than 50 °C, it is determined that the soot accumulation thickness has reached the set soot cleaning thickness, and the control system starts the on-line soot cleaning device;

[0013] 4) The on-line soot cleaning device moves along the track to the outside of the flue at the part of the heat exchanger that needs soot cleaning; several soot cleaning points are arranged along the height direction of the heat exchanger, and the platform plate is lifted to each corresponding soot cleaning point through the lifting mechanism to perform soot cleaning operations respectively;

[0014] 5) The vibrator is provided with an elastic rod and a vibration head. During soot cleaning, one end of the elastic rod with the vibration head opens the baffle and extends into the flue, and moves to the gap between two rows of heat exchange elements. During the moving process, the other end of the elastic rod is knocked by the knocker, so that the vibration head generates vibration and knocks the corresponding two rows of heat exchange elements, so that the dust attached to the surface of the heat exchange elements falls to the bottom of the flue; the dust falling to the bottom of the flue is centrally cleaned after the soot cleaning is completed.

[0015] The knocker consists of a column and an electric telescopic rod, and the electric telescopic rod is arranged on the platform plate through the column.

[0016] The vibrator consists of a vertical rod, an elastic rod and a vibration head. The elastic rod is arranged on the platform plate through the vertical rod. The elastic rods on both sides of the vertical rod are respectively a long rod section and a short rod section. The vibration head is arranged at the outer end of the long rod section, and the short rod section is the knocking section of the knocker.

[0017] The top of the baffle is rotatably connected to the side wall of the flue. When the soot cleaning operation is not carried out, the baffle closes the corresponding through hole under the action of gravity; when the soot cleaning operation is carried out, the baffle rotates towards the inside of the flue under the action of the elastic rod; a retaining piece is arranged on the elastic rod to temporarily close the corresponding through hole during soot cleaning.

[0018] The temperature measuring device for the tube wall is a thermocouple. The thermocouple is arranged on the surface of the heat exchanger at the corresponding position and transmits the measured real-time tube wall temperature data to the control system; the difference between the theoretical tube wall temperature and the measured tube wall temperature is calculated according to the following formula:

[0019] T 理论 =(M 外 ×T 外 ×h 外 +M 内 ×T 内 ×h内 ) / (M 外 ×h 外 +M 内 ×h 内 ); (1)

[0020] △T = T 理论 -T 实测 (2)

[0021] In the formula:

[0022] T 理论 -- Wall temperature calculated theoretically;

[0023] M 外 -- Heat transfer area outside the pipe;

[0024] T 外 -- Temperature of the medium outside the pipe;

[0025] h 外 -- Heat transfer coefficient outside the pipe;

[0026] M 内 -- Heat transfer area inside the pipe;

[0027] T 内 -- Temperature of the medium inside the pipe;

[0028] H 内 -- Heat transfer coefficient inside the pipe;

[0029] T 实测 — Wall temperature measured actually;

[0030] △T -- Difference between the theoretical wall temperature and the measured wall temperature.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] A plurality of soot cleaning ports are arranged on the side wall of the flue where the heat exchanger is located. The control system judges whether the soot accumulation thickness on the surface of the heat exchanger reaches the set soot cleaning thickness through the real-time temperature measurement data of the thermocouple. When the set soot cleaning thickness is reached, the control system controls the vibration soot cleaning device to perform soot cleaning, which can effectively extend the overhaul period of the heat exchanger, reduce the production cost, ensure the heat exchange efficiency of the heat exchanger, and extend the service life of the heat exchanger. Brief Description of the Drawings

[0033] Figure 1 is a schematic diagram of an on-line vibration soot cleaning method for a heat exchanger according to the present invention.

[0034] Figure 2 is a partial schematic view of the vibration soot cleaning device according to the present invention Figure 1 .

[0035] Figure 3It is a partial schematic diagram of the vibration ash cleaning device described in the present invention Figure 2 。

[0036] Figure 4 It is a schematic diagram of the setting form of the ash cleaning port described in the present invention

[0037] In the figure: 1. Flue 2. Heat exchange element 3. Ash cleaning port 4. Vibrator 41. Vertical rod 42. (Elastic rod) Short rod section 43. (Elastic rod) Long rod section 44. Vibration head 45. Baffle 5. Knocking device 51. Column 52. Electric telescopic rod 6. Platform plate 7. Longitudinal track 8. Transverse track 9. Mobile trolley 10. Lifting mechanism Specific embodiments

[0038] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings

[0039] As Figures 1 - 4 shown, an on-line vibration ash cleaning method for a heat exchanger described in the present invention includes the following processes

[0040] 1) The heat exchanger is arranged in the flue 1 of the heating furnace and is composed of multiple rows of heat exchange elements 2; a plurality of rows of ash cleaning ports 3 are arranged on one side of the flue 1 corresponding to the installation position of the heat exchanger; the ash cleaning port 3 is composed of a plurality of through holes arranged at intervals, and each through hole is closed by a baffle arranged in the flue 1

[0041] 2) An on-line ash cleaning of the heat exchanger is carried out by using a vibration ash cleaning device; the vibration ash cleaning device is composed of a mobile trolley 9, a lifting mechanism 10, a platform plate 6, a knocking device 5 and a vibrator 4; the mobile trolley 9 is arranged on the track and can move horizontally and longitudinally along the track; the platform plate 6 is arranged on the mobile trolley 9 through the lifting mechanism 10; the knocking device 5 and the vibrator 4 are both arranged on the platform plate 6

[0042] 3) Wall temperature measuring devices are arranged at multiple parts of the heat exchanger, and the wall temperature measuring devices send the measured temperature data in real time to the control system. The control system calculates the difference between the theoretical wall temperature and the measured wall temperature. When the difference is greater than 50 °C, it is determined that the ash accumulation thickness reaches the set ash cleaning thickness, and the control system starts the vibration ash cleaning device

[0043] 4) The vibration ash cleaning device moves along the track to the outside of the flue 1 at the part of the heat exchanger that needs ash cleaning; a number of ash cleaning points are arranged along the height direction of the heat exchanger, and the platform plate 6 is lifted to each corresponding ash cleaning point through the lifting mechanism 10 to carry out ash cleaning operations respectively

[0044] 5) The vibrator 4 is provided with an elastic rod and a vibration head 44. During ash cleaning, one end of the elastic rod with the vibration head 44 abuts against the baffle plate and extends into the flue 1, and moves into the gap between two rows of heat exchange elements 2. During the movement, the other end of the elastic rod is struck by the striker 5, causing the vibration head 44 to vibrate and strike the corresponding two rows of heat exchange elements 2, so that the dust adhering to the surface of the heat exchange elements 2 falls to the bottom of the flue 1; the dust falling to the bottom of the flue 1 is centrally cleaned after the ash cleaning is completed.

[0045] The striker 5 is composed of a column 51 and an electric telescopic rod 52, and the electric telescopic rod 52 is arranged on the platform plate 6 through the column 51.

[0046] The vibrator 4 is composed of a vertical rod 41, an elastic rod and a vibration head 44. The elastic rod is arranged on the platform plate 6 through the vertical rod 41. The elastic rods on both sides of the vertical rod 41 are respectively a long rod section 43 and a short rod section 42. The outer end of the long rod section 43 is provided with the vibration head 44, and the short rod section 42 is the striking section of the striker 5.

[0047] The top of the baffle plate is rotatably connected to the side wall of the flue 1. When the ash cleaning operation is not carried out, the baffle plate closes the corresponding through hole under the action of gravity; when the ash cleaning operation is carried out, the baffle plate rotates inward to the flue 1 under the action of the elastic rod; a retaining piece 45 is arranged on the elastic rod to temporarily close the corresponding through hole during ash cleaning.

[0048] The tube wall temperature measuring device is a thermocouple, and the thermocouple is arranged on the surface of the corresponding position of the heat exchanger to transmit the measured real-time tube wall temperature data to the control system; the difference between the theoretical tube wall temperature and the measured tube wall temperature is calculated according to the following formula:

[0049] T 理论 =(M 外 ×T 外 ×h 外 +M 内 ×T 内 ×h 内 ) / (M 外 ×h 外 +M 内 ×h 内 ); (1)

[0050] △T=T 理论 -T 实测 (2)

[0051] In the formula:

[0052] T 理论 --The theoretically calculated tube wall temperature;

[0053] M 外 --The heat transfer area outside the tube;

[0054] T 外--Temperature of the medium outside the pipe;

[0055] h 外 --Heat transfer coefficient outside the pipe;

[0056] M 内 --Inner heat transfer area of the pipe;

[0057] T 内 --Temperature of the medium inside the pipe;

[0058] H 内 --Heat transfer coefficient inside the pipe;

[0059] T 实测 —Actually measured wall temperature of the pipe;

[0060] △T--Difference between the theoretical wall temperature and the actually measured wall temperature.

[0061] For the online vibration soot cleaning method of a heat exchanger according to the present invention, a certain number of wall temperature measuring devices are arranged on the heat exchange element 2 of the heat exchanger. Whether the soot on the heat exchange pipe surface reaches the set soot cleaning thickness is determined by temperature measurement. When it is determined that the soot on the heat exchange pipe surface reaches the set soot cleaning thickness, the vibration soot cleaning device is automatically started for online soot cleaning. First, the device provided with the vibrator 4 and the hammer 5 is moved to the corresponding position, and then the vibrator 4 is struck by the hammer 5, and the heat exchange element 2 is struck and vibrated by the vibration head 44 provided on the vibrator 4 to achieve the effect of online soot cleaning.

[0062] When the vibration soot cleaning device is operating, it can be switched between the manual mode and the automatic mode. The manual mode is to manually move the vibration soot cleaning device and control the vibration time. The automatic mode is to interlock the vibration soot cleaning device with the wall temperature measuring device through the control system, and the control system automatically controls the movement of the vibration soot cleaning device and performs the soot cleaning operation. The vibration soot cleaning route can also be preset in the control system, so that the vibration soot cleaning device performs cyclic vibration soot cleaning according to the set soot cleaning route.

[0063] The structure of the vibration soot cleaning device is as Figure 1 shown. The bottom of the moving trolley 9 is provided with rollers and can move along the tracks (including the longitudinal track 7 and the transverse track 8) to achieve horizontal movement. The vertical movement of the mechanism including the vibrator 4 and the hammer 5 can be achieved through the lifting mechanism 10. A plurality of soot cleaning points (such as divided into three soot cleaning points: low, medium, and high) can be set along the height direction of the heat exchanger, and soot cleaning operations are respectively performed at each soot cleaning point.

[0064] The structure of the hammer 5 is as Figure 2 shown, and the structure of the vibrator 4 is as Figure 3As shown in the figure, the hammer 5 and the vibrator 4 are fixed in relative positions through the platform plate 6. The hammer 5 strikes the short rod section 42 of the vibrator 4 through the electric telescopic rod 52, and amplifies the striking amplitude through the elastic rod, so that the vibration head 44 at the other end of the elastic rod swings. The vibration head 44 swings between two adjacent heat exchange elements 2, and transmits the vibration to the heat exchange element 2, thereby achieving the effect of vibration dust cleaning.

[0065] Figure 4 It is a schematic diagram of the setting of the dust cleaning port 3. Select the opening position and size of the dust cleaning port 3 according to the installation position and specifications of the heat exchanger. Multiple through holes can be set in each row of dust cleaning ports 3, and baffles larger than the through hole area are installed inside the through holes. The baffles are made of different materials and thicknesses according to the temperature and working conditions of the flue 1. The through holes are opened unidirectionally inward through the baffles to prevent the flue gas from escaping during the normal production of the heating furnace. The through holes can be temporarily closed during dust cleaning through the baffles 45 provided on the elastic rod to ensure that the flue gas will not escape from the through holes during dust cleaning.

[0066] In the present invention, the pipe wall temperature measuring device for measuring the surface temperature of the heat exchanger can adopt a thermocouple. When the temperature of the flue gas in the flue changes little, the thermocouple can be interlocked with the control system to achieve automatic dust cleaning. Utilizing the characteristics of the thermocouple being heat-resistant and bendable, the thermocouple is fixed on the surface of the heat exchange element 2. When the surface of the heat exchange element 2 is fouled, the temperature data measured by the thermocouple will decrease, thereby realizing the judgment of whether the fouling thickness of the heat exchanger reaches the cleaning requirement.

[0067] The above is only the 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, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An online vibration soot cleaning method for a heat exchanger, characterized in that, It includes the following processes: 1) The heat exchanger is arranged in the flue of the heating furnace and consists of multiple rows of heat exchange elements; multiple rows of soot cleaning openings are arranged on one side of the flue corresponding to the installation position of the heat exchanger; the soot cleaning openings are composed of multiple through holes arranged at intervals, and each through hole is closed by a baffle arranged in the flue; 2) An on-line soot cleaning device is used to clean the heat exchanger; the on-line soot cleaning device consists of a mobile trolley, a lifting mechanism, a platform plate, a knocker and a vibrator; the mobile trolley is arranged on the track and can move horizontally and vertically along the track; the platform plate is arranged on the mobile trolley through the lifting mechanism; the knocker and the vibrator are both arranged on the platform plate; 3) Temperature measuring devices for the tube walls are arranged at multiple positions of the heat exchanger, and the temperature measuring devices for the tube walls send the measured temperature data in real time to the control system. The control system calculates the difference between the theoretical tube wall temperature and the measured tube wall temperature. When the difference is greater than 50 °C, it is determined that the ash accumulation thickness has reached the set soot cleaning thickness, and the control system starts the on-line soot cleaning device; 4) The on-line soot cleaning device moves along the track to the outside of the flue at the part of the heat exchanger that needs soot cleaning; several soot cleaning points are arranged along the height direction of the heat exchanger, and the platform plate is lifted to each corresponding soot cleaning point through the lifting mechanism to perform soot cleaning operations respectively; 5) The vibrator is provided with an elastic rod and a vibration head. During soot cleaning, one end of the elastic rod with the vibration head opens the baffle and extends into the flue, and moves into the gap between two rows of heat exchange elements. During the moving process, the other end of the elastic rod is knocked by the knocker, so that the vibration head generates vibration and knocks the corresponding two rows of heat exchange elements, making the dust attached to the surface of the heat exchange elements fall to the bottom of the flue; the dust that has fallen to the bottom of the flue is centrally cleaned after the soot cleaning is completed.

2. The online vibration soot cleaning method for a heat exchanger according to claim 1, wherein The knocker consists of a column and an electric telescopic rod, and the electric telescopic rod is arranged on the platform plate through the column.

3. The online vibration soot cleaning method of a heat exchanger according to claim 1, characterized in that, The vibrator consists of a vertical rod, an elastic rod and a vibration head. The elastic rod is arranged on the platform plate through the vertical rod. The elastic rods on both sides of the vertical rod are respectively a long rod section and a short rod section, and the vibration head is arranged at the outer end of the long rod section, and the short rod section is the knocking section of the knocker.

4. A method for online vibration soot cleaning of a heat exchanger according to claim 3, characterized in that, The top of the baffle is rotatably connected to the side wall of the flue. When no soot cleaning operation is carried out, the baffle closes the corresponding through hole under the action of gravity; when the soot cleaning operation is carried out, the baffle rotates towards the inside of the flue under the action of the elastic rod; a retaining piece is arranged on the elastic rod to temporarily close the corresponding through hole during soot cleaning.

5. A method for online vibration soot cleaning of a heat exchanger according to claim 1, characterized in that, The temperature measuring device for the tube wall is a thermocouple, and the thermocouple is arranged on the surface of the heat exchanger at the corresponding position, and transmits the measured real-time tube wall temperature data to the control system; the difference between the theoretical tube wall temperature and the measured tube wall temperature is calculated according to the following formula: T 理论 = (M 外 × T 外 × h 外 + M 内 × T 内 × h 内 ) / (M 外 × h 外 + M 内 × h 内 ); ( 1) △T=T 理论 -T 实测 (2) In the formula: T 理论 --Wall temperature calculated theoretically; M 外 --Heat transfer area outside the tube; T 外 --Temperature of the medium outside the pipe; h 外 --Heat transfer coefficient outside the tube; M 内 --Heat transfer area inside the pipe; T 内 -- Temperature of the medium inside the pipe; H 内 - Heat transfer coefficient inside the pipe; T 实测 — The actually measured pipe wall temperature; △T - the difference between the theoretical tube wall temperature and the measured tube wall temperature.

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