A boiler hot air preheating device

Abstract

The present invention relates to the technical field of boiler equipment, and specifically discloses a boiler hot air preheating device, comprising a rotary air preheater arranged on the flue at the rear of the boiler, and a control device connected to the rotary air preheater; wherein the control device is used to control and adjust the rotation speed of the rotary air preheater according to the primary hot air temperature, secondary hot air temperature and flue gas temperature of the boiler collected in real time, so that the outlet flue gas temperature of the rotary air preheater is greater than the melting point temperature of ammonium bisulfate. In this application, based on the temperature requirements of the boiler for the primary hot air and secondary hot air, and the actual flue gas temperature discharged from the flue of the boiler, the rotation speed of the rotary air preheater is controlled so that the temperature of the flue gas is maintained at a temperature greater than the melting point temperature of ammonium bisulfate, thereby avoiding the problem of ammonium bisulfate precipitating and scaling inside the rotary air preheater, which is beneficial to improving the service life and performance of the rotary air preheater.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler equipment, in particular to a boiler hot air preheating device. Background Art

[0002] Air preheater, also known as air preheater, is a device that can improve the heat exchange performance of the boiler. Its main function is to use the high-temperature flue gas discharged from the boiler flue to exchange heat with the heat storage element in the air preheater, and preheat the air that needs to be introduced into the boiler in advance, so that the air is heated before entering the boiler, reducing heat loss in the boiler.

[0003] However, to meet environmental protection policy requirements, boiler equipment must be installed with an SCR denitrification device. However, the ammonia injected into the SCR reactor cannot fully react, resulting in ammonia leakage. Furthermore, sulfur dioxide in the flue also reacts with the SCR denitrification device to produce sulfur trioxide, which in turn reacts with the escaped nitrogen to form ammonium bisulfate. As the flue gas passes through the air preheater, this ammonium bisulfate condenses and forms deposits on the heat storage elements. The accumulation of this deposit corrodes the heat storage elements, reducing their service life. It also affects airflow within the air preheater, affecting the thermal conductivity of the elements.

[0004] Currently, the main method for dealing with deposits in air preheaters is to regularly flush the heat storage elements in the air preheaters. However, it is difficult to remove the deposits and it is often difficult to achieve the ideal removal effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a boiler hot air preheating device, which can reduce the problem of ammonia bisulfate scaling deposition in the air preheater to a certain extent and ensure the service life and performance of the air preheater.

[0006] In order to solve the above technical problems, the present invention provides a boiler hot air preheating device, comprising a rotary air preheater arranged on the tail flue of the boiler, and a control device connected to the rotary air preheater;

[0007] Among them, the control device is used to control and adjust the rotation speed of the rotary air preheater according to the real-time collected primary hot air temperature, secondary hot air temperature and flue gas temperature of the boiler, so that the outlet flue gas temperature of the rotary air preheater is greater than the melting point temperature of ammonium bisulfate.

[0008] In an optional embodiment of the present application, the rotary air preheater further comprises two steam soot blowing devices for cleaning the ammonia bisulfate scale on the rotary air preheater from the top and bottom respectively;

[0009] The height of the rotary air preheater does not exceed a preset height; the preset height is twice the maximum cleaning height of the rotary air preheater by a single steam soot blowing device.

[0010] In an optional embodiment of the present application, a tubular preheater is further included, wherein the hot air inlet of the tubular preheater is connected to the flue gas outlet of the rotary air preheater; the two hot air outlets of the tubular preheater are respectively connected to the two cold air inlets of the rotary air preheater;

[0011] The tubular preheater is connected to the control device, and the control device is used to control the tubular preheater to cool the flue gas discharged from the flue gas outlet of the rotary air preheater to a flue gas temperature lower than a set temperature.

[0012] In an optional embodiment of the present application, a compressed air soot blower and a spraying device for blowing soot to clean the tubular preheater are also included.

[0013] In an optional embodiment of the present application, a collecting device connected to the output end of the tubular preheater is further included, for collecting ammonia bisulfate from the flue gas output through the tubular preheater.

[0014] In an optional embodiment of the present application, the collecting device includes a plurality of columns perpendicular to the flow direction of the flue gas, a steam soot blower, and a collector;

[0015] The cross section of the column is narrow on both sides and wide in the middle along the flow direction of the flue gas;

[0016] The steam soot blower is used to spray water vapor with a temperature higher than the melting point of ammonium bisulfate onto the surface of each column;

[0017] The collector is used to collect waste water used for cleaning the surface of the column.

[0018] In an optional embodiment of the present application, the surface of the column facing the flow direction of the smoke is formed by two convex curved surfaces, the cross-sectional width of which gradually decreases along the flow direction, and the cross-section is a semi-elliptical surface;

[0019] The surface of the column facing away from the flow direction of the smoke is formed by two concave curved surfaces, the cross-sectional width of which gradually increases along the flow direction, and the cross-sectional surface is in an "eight" shape.

[0020] The present invention provides a boiler hot air preheating device, comprising a rotary air preheater arranged on the boiler tail flue, and a control device connected to the rotary air preheater; wherein the control device is used to control and adjust the rotation speed of the rotary air preheater according to the real-time collected primary hot air temperature, secondary hot air temperature and flue gas temperature in the flue, so that the outlet flue gas temperature of the rotary air preheater is greater than the melting point temperature of ammonium bisulfate.

[0021] In the present application, in the process of controlling the operation of the rotary air preheater to utilize the flue gas in the flue to heat the cold air to obtain hot air, the rotation speed of the rotary air preheater is controlled based on the temperature requirements of the boiler for the primary hot air and the secondary hot air, and the actual flue gas temperature discharged from the flue of the boiler, so that the temperature of the flue gas when discharged from the rotary air preheater is also maintained at a temperature greater than the melting point of ammonium bisulfate; thereby, it is ensured that the temperature of the flue gas is always maintained at a temperature greater than its melting point during the entire process of passing through the rotary air preheater, thus avoiding the problem of precipitation and scaling of ammonium bisulfate inside the rotary air preheater to a large extent, thereby greatly reducing the sediment attached to the heat storage element in the rotary air preheater, which is beneficial to improving the service life and performance of the rotary air preheater. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of the structure of a boiler hot air preheating device provided in an embodiment of the present application;

[0024] Figure 2 It is a structural diagram of a rotary air preheater;

[0025] Figure 3 A schematic structural diagram of a clean rotary air preheater provided in an embodiment of the present application;

[0026] Figure 4 Another structural schematic diagram of the boiler hot air preheating device provided in an embodiment of the present application;

[0027] Figure 5 This is a schematic diagram of the top view of the collection device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] During normal boiler operation, air must be regularly introduced into the boiler to ensure sufficient combustion of the coal. However, the temperature inside the boiler furnace is often relatively high. Directly introducing cold air at room temperature into the furnace will inevitably lead to heat loss due to the high temperature. Therefore, the cold air must be heated before being introduced into the furnace. The flue gas discharged from the boiler through the flue is generally at a higher temperature, but this exhaust gas is often discarded, resulting in a waste of heat from the high-temperature flue gas.

[0029] In order to utilize the heat of flue gas, a rotary air preheater is connected to the flue of the boiler, and the primary cold air and secondary cold air at room temperature and the high-temperature flue gas are respectively introduced into the rotary air preheater, so that the primary cold air and secondary cold air respectively pass through the heat storage elements in the rotary air preheater and generate heat exchange with the high-temperature flue gas, and then are heated to the primary hot air temperature and secondary hot air temperature required by the boiler, and then introduced into the boiler; and the high-temperature flue gas that absorbs heat is discharged from the rotary air preheater after its temperature drops.

[0030] Currently, in order to maximize the utilization of flue gas heat in the boiler flue, it is often believed that the higher the flue gas heat absorption efficiency, the better. Therefore, in practical applications, the operation of the rotary air preheater is often controlled based on the principle of maximizing flue gas heat absorption. However, this operating principle ignores the condensation and precipitation of ammonium bisulfate in the flue gas at low temperatures. As a result, the ammonium bisulfate in the flue gas, which has been cooled to a relatively low temperature in the rotary air preheater, forms a large amount of sediment in the rotary air preheater. The sediment in the rotary air preheater is relatively difficult to clean, which directly affects the service life and performance of the rotary air preheater.

[0031] To this end, the present application proposes to inhibit the scaling deposition of ammonium bisulfate in the rotary air preheater by increasing the temperature of the flue gas in the rotary air preheater, thereby extending the service life and performance of the rotary air preheater to a certain extent.

[0032] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] Reference Figures 1 to 5 , Figure 1 A schematic diagram of the structure of a boiler hot air preheating device provided in an embodiment of the present application; Figure 2 It is a structural diagram of a rotary air preheater; Figure 3A schematic structural diagram of a clean rotary air preheater provided in an embodiment of the present application; Figure 4 Another structural schematic diagram of the boiler hot air preheating device provided in an embodiment of the present application; Figure 5 This is a schematic diagram of the top view of the collection device provided in an embodiment of the present application.

[0034] In a specific embodiment of the present application, the boiler hot air preheating device may include:

[0035] A rotary air preheater 10 provided on the tail flue of the boiler, and a control device connected to the rotary air preheater 10;

[0036] Among them, the control device is used to control and adjust the rotation speed of the rotary air preheater 10 according to the real-time collected primary hot air temperature, secondary hot air temperature and flue gas temperature in the boiler, so that the outlet flue gas temperature of the rotary air preheater 10 is greater than the melting point temperature of ammonium bisulfate.

[0037] like Figure 2 As shown, the heat storage elements 11 of the rotary air preheater 10 are generally distributed in a circular shape; the rotation direction of the heat storage elements 11 of the rotary air preheater 10 can be counterclockwise or clockwise. Taking counterclockwise rotation as an example, during the operation of the rotary air preheater 10, the three fan-shaped plates divide the area where the heat storage elements 11 are located into three different areas, among which the flue gas side between fan-shaped plate 1 and fan-shaped plate 2 is the flue gas flow area; the secondary air side between fan-shaped plate 2 and fan-shaped plate 3 is the secondary air flow area; the primary air side between fan-shaped plate 3 and fan-shaped plate 1 is the primary air flow area; for each heat storage element 11, when it rotates to the flue gas side, it can exchange heat with the flue gas and thus the temperature When it rises and rotates to the secondary air side, it exchanges heat with the secondary cold air introduced, so that the temperature of the secondary cold air increases and becomes secondary hot air which is output to the furnace; the heat storage element 11 continues to rotate to the primary air side and heats the primary cold air, so that its temperature increases and primary hot air is output; finally, the heat storage element 11 rotates to the fan plate 1, and after the temperature drops to the lowest, it rotates back into the flue gas side and absorbs the heat of the flue gas to increase the temperature; this cycle is repeated to realize the utilization of the heat of the flue gas.

[0038] It is understood that by changing the time it takes for the rotary air preheater 10 to rotate once, the heat exchange rate between the flue gas and the cold air can be changed, which in turn changes the flue gas temperature to a certain extent, thereby controlling the cold end temperature of the rotary air preheater 10, i.e., the flue gas outlet temperature. Because the flue gas has the lowest temperature during the process of entering and flowing out of the rotary air preheater 10, i.e., the temperature at the flue gas outlet of the rotary air preheater 10, if the temperature of the flue gas at the flue gas outlet is controlled to be greater than the melting point of ammonium bisulfate in the flue gas, it can be ensured that the temperature of the flue gas is always maintained above the melting point of ammonium bisulfate throughout the process of passing through the rotary air preheater 10, thereby largely avoiding the problem of ammonium bisulfate in the flue gas condensing on the heat storage element 11.

[0039] In addition, during the production operation of the boiler, there may be different requirements for the primary air temperature, secondary air temperature and air volume as the quality of the coal entering the furnace changes. According to the changes in the requirements of the primary air temperature and secondary air temperature during operation, the rotation direction of the rotary air preheater 10 can be changed as the quality of the coal entering the furnace changes to balance the primary air temperature and the secondary air temperature.

[0040] Furthermore, the current method for cleaning the deposits on the heat storage element 11 in the rotary air preheater 10 is mostly to use a steam soot blowing device. Specifically, two single-gun telescopic steam soot blowing devices can be used to extend into the rotary air preheater 10 from the top and bottom of the rotary air preheater 10 respectively. The steam soot blowing device at the top sprays high-temperature water vapor downward, and the steam soot blowing device at the bottom sprays high-temperature water vapor upward. However, the injection height of the high-temperature water vapor injected by the current single-gun telescopic steam soot blowing device, that is, the cleaning height is limited. The current rotary air preheater 10 is relatively high in the vertical direction, approximately between 2.2m and 2.5m. This means that even if two single-gun telescopic steam soot blowing devices are used to clean the rotary air preheater 10 from the top and bottom respectively, the middle area of ​​the rotary air preheater 10 cannot be cleaned, which in turn causes scaling in the middle part and corrosion in the lower part of the heat storage element 11 in the rotary air preheater 10.

[0041] Therefore, in order to improve the cleaning effect of the heat storage element 11 in the rotary air preheater 10, refer to Figure 3 In an optional embodiment of the present application, it may further include:

[0042] Two steam soot blowing devices 20 for cleaning the ammonia bisulfate scale on the rotary air preheater 10 from the top and bottom respectively;

[0043] The height of the rotary air preheater 10 does not exceed a preset height; the preset height is twice the maximum cleaning height of the rotary air preheater 10 by a single steam sootblowing device 20 for sootblowing cleaning.

[0044] Reference Figure 3 It is understood that the maximum cleaning height of a single steam sootblower 20 in this embodiment is the maximum spraying height that can be achieved when the single steam sootblower 20 extends into the rotary air preheater 10 and sprays high-temperature steam in the vertical direction. Because the vertical height of the rotary air preheater 10 does not exceed twice the maximum cleaning height, a single steam sootblower 20 can clean at least half of the area of ​​the rotary air preheater 10 in the vertical direction. The cleaning steam sprayed by two steam sootblowers 20 can vertically blow through the heat storage element 11 of the rotary air preheater 10, thereby improving the cleaning effect of the rotary air preheater 10 to a certain extent.

[0045] Furthermore, considering that although the control of the rotation speed of the rotary air preheater 10 and the reduction of the height of the rotary air preheater 10 can reduce the deposition of ammonium bisulfate on the heat storage element 11 to a certain extent, the temperature of the flue gas discharged from the rotary air preheater 10 is still relatively high, and direct discharge obviously also causes heat waste to a certain extent; for this reason, referring to Figure 4 In an optional embodiment of the present application, the boiler hot air preheating device may further include:

[0046] The tubular preheater 30 has its hot air inlet connected to the flue gas outlet of the rotary air preheater 10; the two hot air outlets of the tubular preheater 30 are respectively connected to the two cold air inlets of the rotary air preheater 10;

[0047] The tubular preheater 30 is connected to a control device, which is used to control the tubular preheater to cool the flue gas discharged from the flue gas outlet of the rotary air preheater 10 to a flue gas temperature lower than a set temperature.

[0048] As mentioned above, the rotary air preheater 10 includes a flue gas inlet, a flue gas outlet, two cold air inlets for respectively introducing primary cold air and secondary cold air, and two hot air outlets for respectively outputting primary hot air and secondary hot air.

[0049] Similarly, the tubular preheater 30 may also include a hot air inlet for introducing flue gas, two cold air inlets for introducing cold air, and two hot air outlets for outputting heated cold air.

[0050] Therefore, during actual operation, the flue gas first passes through the rotary air preheater 10 and the heat storage element 11 for heat exchange, and is cooled to a temperature higher than that of ammonium bisulfate. After being discharged from the rotary air preheater 10, the flue gas enters the tubular preheater 30 through the hot air inlet of the tubular preheater 30 and undergoes heat exchange again, thereby further cooling the flue gas so that it is finally discharged from the flue gas outlet of the tubular preheater 30 at a temperature lower than the set temperature that meets the emission requirements.

[0051] On this basis, the tubular preheater 30 can also preheat the cold air first, and the cold air at room temperature first enters the tubular preheater 30 through the two cold air inlets of the tubular preheater 30 respectively. The two cold air can be used as primary cold air and secondary cold air respectively. The heat released by the flue gas is absorbed in the tubular preheater 30, so that the primary cold air and the secondary cold air are initially heated and the temperature is increased. Then, they pass through a hot air outlet of the tubular preheater 30 and the primary cold air inlet of the rotary air preheater 10, as well as through another hot air outlet of the tubular preheater 30 and the secondary cold air inlet of the rotary air preheater 10, and enter the rotary air preheater 10 respectively and are heated again by the heat storage element. Finally, the primary cold air and the secondary cold air are heated to form the primary hot air temperature and the secondary hot air temperature required for boiler operation, and then are input into the furnace.

[0052] It can be seen that in this embodiment, it is equivalent to using a rotary air preheater 10 and a tubular preheater 20 in combination to absorb and utilize the heat of the flue gas for a second time, thereby ensuring the utilization rate of the flue gas heat while avoiding the large-scale scaling of ammonium bisulfate in the rotary air preheater 10.

[0053] Furthermore, in order to enable the control device to more flexibly adjust the primary hot air temperature, secondary hot air temperature, primary hot air flow rate, and secondary hot air flow rate based on the actual needs in the boiler furnace, baffles can be further provided on the air flow duct between the primary cold air inlet of the rotary air preheater 10 and a hot air outlet of the connected tube-type preheater 30, and on the air flow duct between the secondary cold air inlet of the rotary air preheater 10 and another hot air outlet of the connected tube-type preheater 30, so that the air flow rate and flow velocity of the primary cold air and secondary cold air flowing into the rotary air preheater 10 can be adjusted through the baffles.

[0054] In addition, for the tubular preheater 30, although the flue gas inside it will be cooled to below the melting point of ammonium bisulfate, thereby causing the ammonium bisulfate to form deposits in the tubular preheater 30; however, compared with the rotary air preheater 10, the size of the tubular preheater 30 is much smaller than that of the rotary air preheater 10, and the difficulty of cleaning the ammonium bisulfate deposits inside it is relatively small. Even if the tubular preheater 30 is replaced, its replacement cost is less than the replacement cost of the rotary air preheater 10.

[0055] Therefore, in another embodiment of the present application, it may further include:

[0056] Compressed air soot blower and spray device for soot cleaning the tubular preheater 30.

[0057] It should be noted that the air soot blower can spray hot air into the tubular preheater 30 to remove dust attached to the surface of its internal components, and regularly clean its internal components through a spray device to eliminate the ammonium bisulfate scaling problem.

[0058] Furthermore, considering that a large amount of ammonium bisulfate may be present in the flue gas discharged directly from the tubular preheater, if the flue gas is discharged directly into the subsequent dust collector and induced draft fan, it may have a negative impact on the dust collector. Therefore, in an optional embodiment of the present application, the following may be further included:

[0059] The collecting device 40 connected to the output end of the tubular preheater 30 is used to collect ammonia bisulfate from the flue gas output through the tubular preheater 30 .

[0060] The collecting device 40 can have many different forms, such as Figure 5 As shown, in an optional embodiment of the present application, the collecting device 40 may include:

[0061] A plurality of columns 41, steam soot blowers 42 and collectors perpendicular to the flow direction of the flue gas;

[0062] The cross section of the column 41 is narrow on both sides and wide in the middle along the flow direction of the smoke;

[0063] The steam soot blower 42 is used to spray water vapor with a temperature higher than the melting point of ammonium bisulfate onto the surface of each column 41.

[0064] exist Figure 5 In the embodiment shown, each column is vertically arranged perpendicular to the direction of smoke flow. Figure 5 The schematic diagram shown is a top view from the viewing direction from top to bottom.

[0065] When the flue gas flows through the columns 41, the columns 41 slow down the flue gas flow rate to a certain extent, and the flue gas temperature is relatively low at this time, which facilitates the deposition of ammonium bisulfate on the columns 41. When the flue gas stops flowing, multiple steam soot blowers can be inserted between the columns 41 to spray water vapor with a temperature higher than the melting point of ammonium bisulfate onto the surface of each column 41, thereby cleaning the ammonium bisulfate deposited on the surface of the columns 41 and flowing it into the collector along with the cleaning wastewater.

[0066] In addition, in this embodiment, each column 41 is configured to have a cross-section that is narrow on both sides and wide in the middle along the flow direction of the flue gas. This allows the flue gas to flow through each column 41 in a manner that first narrows and then widens, forming a process of first accelerating and then decelerating. This makes it easier for ammonium bisulfate to deposit on the surface of each column 41 that is opposite to the flow direction of the flue gas, thereby improving the adsorption effect of ammonium bisulfate.

[0067] like Figure 5 As shown, a specific embodiment of the present application may include:

[0068] The surface of the column 41 facing the flow direction of the smoke is formed by two convex curved surfaces, the cross-sectional width of which gradually decreases along the flow direction, and the cross-sectional surface is semi-elliptical;

[0069] The surface of the column 41 facing away from the flow direction of the smoke is formed by two concave curved surfaces, the cross-sectional width of which gradually increases along the flow direction, and the cross-sectional surface is in the shape of an "eight".

[0070] The embodiment shown in Figure 5 is a typical embodiment structure that can make the smoke accelerate first and then decelerate. Of course, in actual application, other similar structures of the pillars 41 can also be used in this application, which are not listed one by one in this application.

[0071] To sum up, the boiler hot air preheating equipment in the present application fully considers the problem that when the flue gas heat dissipates too much and the flue gas temperature is too low, the deposition structure of ammonium bisulfate deposits in the rotary air preheater will increase. In controlling the operation of the rotary air preheater, the rotation speed of the rotary air preheater is reasonably controlled according to the temperature requirements of the boiler for the primary hot air and the secondary hot air, as well as the actual flue gas temperature discharged from the flue of the boiler, so that the temperature of the flue gas when it is discharged from the rotary air preheater is also maintained at a temperature greater than the melting point of ammonium bisulfate; thereby, the flue gas is always kept at a temperature greater than the melting point of ammonium bisulfate during the process of passing through the entire rotary air preheater, thereby avoiding the problem of ammonium bisulfate deposition in the rotary air preheater to a large extent, and reducing the sediment attached to the heat storage element in the rotary air preheater, which is beneficial to improving the service life and performance of the rotary air preheater.

[0072] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements are inherent to the elements. In the absence of further restrictions, the elements limited by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are not described in detail in accordance with the corresponding technical solutions in the prior art to achieve the same principle, so as to avoid excessive elaboration.

[0073] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A boiler hot air preheating device, characterized in that: It includes a rotary air preheater arranged on the tail flue of the boiler, and a control device connected to the rotary air preheater; The control device is used to control and adjust the rotation speed of the rotary air preheater according to the real-time collected primary hot air temperature, secondary hot air temperature and flue gas temperature of the boiler, so that the outlet flue gas temperature of the rotary air preheater is greater than the melting point of ammonium bisulfate; It also includes a tubular preheater, wherein the hot air inlet of the tubular preheater is connected to the flue gas outlet of the rotary air preheater; the two hot air outlets of the tubular preheater are respectively connected to the two cold air inlets of the rotary air preheater; The tubular preheater is connected to the control device, and the control device is used to control the tubular preheater to cool the flue gas discharged from the flue gas outlet of the rotary air preheater to a flue gas temperature lower than a set temperature; It also includes a collecting device connected to the output end of the tubular preheater, for collecting ammonia bisulfate from the flue gas output from the tubular preheater; The collecting device includes a plurality of columns perpendicular to the flow direction of the flue gas, a steam soot blower and a collector; The cross section of the column is narrow on both sides and wide in the middle along the flow direction of the flue gas; The steam soot blower is used to spray water vapor with a temperature higher than the melting point of ammonium bisulfate onto the surface of each column; The collector is used to collect waste water used for cleaning the surface of the column.

2. The boiler hot air preheating equipment according to claim 1, characterized in that: It also includes two steam soot blowing devices for cleaning the ammonia bisulfate scale on the rotary air preheater from the top and bottom respectively; The height of the rotary air preheater does not exceed a preset height; the preset height is twice the maximum cleaning height of the rotary air preheater by a single steam soot blowing device.

3. The boiler hot air preheating equipment according to claim 1 or 2, characterized in that: It also includes a compressed air soot blower and a spraying device for blowing soot to clean the tubular preheater.

4. The boiler hot air preheating equipment according to claim 1 or 2, characterized in that: The surface of the column facing the flow direction of the smoke is formed by two convex curved surfaces, the cross-sectional width of which gradually decreases along the flow direction, and the cross-sectional surface is semi-elliptical; The surface of the column facing away from the flow direction of the flue gas is formed by two concave curved surfaces, the cross-sectional width of which gradually increases along the flow direction, and the cross-sectional surface is in an "eight" shape.

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