Heat exchange system and boiler system

Abstract

The invention discloses a heat exchange system and a boiler system.The heat exchange system is internally provided with a rotary heat exchange assembly and a heat pipe assembly at the same time, the temperature of low-temperature gas (primary air or / and secondary air) entering the rotary heat exchange assembly can be increased through the heat pipe assembly, and therefore the smoke temperature of an outlet of the rotary heat exchange assembly is increased; the problems of adhesion and blockage of ammonium bisulfate in the rotary heat exchange assembly are reduced, and meanwhile, due to the fact that the rotary heat exchange assembly has the efficient heat exchange characteristic, the overall heat exchange efficiency of the heat exchange system is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas heat exchange, in particular to a heat exchange system and a boiler system. BACKGROUND

[0002] The flue gas emission temperature of coal-fired power plants and non-electric high-energy-consuming industries is too high, resulting in large energy loss, low equipment thermal efficiency, and increased product energy consumption, which is not conducive to cost reduction for enterprises. In traditional electric power flue gas tail heat collection equipment, the air preheater (air preheater) is an extremely important device. The air preheater is a device that transfers energy from flue gas to boiler combustion air through heat exchange tubes or heat exchange elements in the boiler tail flue. This device can further reduce the boiler flue gas temperature, reduce heat loss, and improve the thermal efficiency of the boiler. It can also be used for drying the boiler pulverizing system, increasing the combustion temperature, and improving the combustion conditions.

[0003] Due to the high heat exchange efficiency of the Junker three-part warehouse air preheater, larger heat exchange fins can be arranged in a smaller space. As the thermal power generator set develops towards large-scale and high-parameterization, the air preheater of the power plant has changed from the tubular air preheater and the rotating air preheater with a wind cover to the widely used Junker rotating air preheater with heat exchange elements (heat storage plates). At the same time, in order to control the emission of the second dust removal device Ox, most coal-fired power plants in China have been modified for denitration, among which the selective catalytic reduction denitration (SCR) has been widely applied due to its mature technology and excellent effect. However, with the increasingly stringent emission requirements of the second dust removal device Ox in ultra-low emission, in the operation process of the power plant, in order to control the emission concentration of the second dust removal device Ox, the ammonia nitrogen ratio is mostly improved, so most of the in-service units have the problem of excessive ammonia injection. The excessive ammonia injected into the flue gas eventually escapes into the downstream air preheater, forming "ammonia escape". With the gradual increase of "ammonia escape", it reacts with the sulfur dioxide and sulfur trioxide carried in the flue gas to form ammonium bisulfate (ABS).

[0004] With the operation of the rotating air preheater, ABS will gradually entrap the ash in the flue gas and adhere to the air preheater, causing the entire air preheater heat exchange surface to be blocked, resulting in increased power consumption of the induced draft fan and increased system resistance. In severe cases, it will also affect the stability and safety of the operation of the coal-fired unit.

[0005] Therefore, how to overcome the above-mentioned defects is a technical problem that technicians in the field have been trying to solve. SUMMARY

[0006] The purpose of the embodiments of the present application is to provide a heat exchange system with relatively high heat exchange efficiency and capable of effectively reducing flue gas blockage. Another purpose of the embodiments of the present application is to provide a boiler system comprising the above heat exchange system.

[0007] The heat exchange system provided by the embodiment of the present application comprises a shell, the interior of the shell comprises a first chamber, a second chamber and a third chamber, the first chamber and the second chamber are arranged side by side in a horizontal direction and are located below the third chamber;

[0008] A rotary heat exchange assembly is located in the third chamber, the rotary heat exchange assembly has a rotary shaft arranged vertically, and the rotary heat exchange assembly comprises at least two heat exchange units arranged in a circumferential direction;

[0009] A heat pipe assembly comprises a plurality of heat pipes, each of the heat pipes comprises a condensing section and an evaporating section, the condensing section is located in the second chamber, and the evaporating section is located in the first chamber;

[0010] The shell further comprises a flue gas inlet, a gas outlet, a flue gas outlet and a gas inlet, the flue gas inlet and the gas outlet are located above the rotary heat exchange assembly, the flue gas inlet can communicate with the flue gas outlet through the heat exchange channels of the heat exchange units on the flue gas side, the first chamber and the second chamber, and part of the heat exchange channels of the heat exchange units;

[0011] In the heat exchange system of the present application, the rotary heat exchange assembly and the heat pipe assembly are arranged simultaneously, high-temperature flue gas first passes through the heat exchange units of the rotary heat exchange assembly and exchanges heat with the primary air and the secondary air heated by the heat pipe assembly, the flue gas after heat exchange in the rotary heat exchange assembly enters the first chamber to heat the medium in the evaporating section of each heat pipe, and the temperature is further reduced, the heated medium in the heat pipe enters the condensing section located in the second chamber and exchanges heat with the primary air or / and the secondary air from the air pipe, thereby heating the primary air or / and the secondary air, and the heated primary air or / and secondary air enters the third chamber and exchanges heat with the high-temperature flue gas.

[0012] As can be known from the above description, in the embodiment of the present application, the temperature of the low-temperature gas (primary air or / and secondary air) entering the rotary heat exchange assembly can be increased by the heat pipe assembly, thereby increasing the outlet flue gas temperature of the rotary heat exchange assembly and reducing the problem of adhesion and blockage of ammonium bisulfate in the rotary heat exchange assembly, and at the same time, the heat exchange system has relatively high heat exchange efficiency due to the high-efficiency heat exchange characteristics of the rotary heat exchange assembly.

[0013] In an example, the first chamber and the second chamber are isolated by an isolation body, the isolation body comprises a support block and a plate structure connected in series along the flue gas flow direction, the thickness of the support block in the horizontal direction is greater than the thickness of the plate structure, and the rotary heat exchange assembly is partially supported on the support block.

[0014] Or / and, characterized in that the second chamber comprises a first sub-chamber and a second sub-chamber arranged in a horizontal direction, the gas inlet comprises a first gas inlet and a second gas inlet, the first sub-chamber is communicated with the first gas inlet, the second sub-chamber is communicated with the second gas inlet, and the upper ends of the first sub-chamber and the second sub-chamber are communicated with the gas outlet through the heat exchange channels in the rotary heat exchange assembly.

[0015] In an example, the second chamber is divided into at least two sub-channels by a partition, the gas inlet and the third chamber are communicated through each of the sub-channels, the heat exchange system further comprises a valve capable of adjusting the opening degree of each of the sub-channels, and at least one heat pipe is arranged in each of the sub-channels.

[0016] The heat exchange system further comprises a controller, which is capable of controlling the opening degree of each of the valves to make the working temperature of at least one of the heat exchange units on the flue gas side be within a preset temperature range.

[0017] In an example, further comprising:

[0018] An acquisition component is configured to acquire at least one of the flue gas inlet pressure or the flue gas outlet pressure or the working temperature of the heat exchange unit in the current state;

[0019] The controller controls the opening degree of each of the valves according to the parameters acquired by the acquisition component to make the working temperature of the heat exchange unit on the flue gas side be within a preset temperature range.

[0020] In an example, further comprising a first ash removal device configured to remove ash from each of the heat exchange units;

[0021] The controller is further capable of starting the first ash removal device to remove ash from at least one of the heat exchange units on the flue gas side according to the parameters acquired by the acquisition component or according to a pre-stored strategy.

[0022] In an example, further comprising a second ash removal device arranged in the first chamber, and the second ash removal device is configured to remove ash from the evaporation section of each of the heat pipes;

[0023] The controller is further capable of closing one or more of the sub-channels to make the surface temperature of the heat pipes be within a first predetermined range according to the acquired working parameters of the heat pipes or according to a pre-stored strategy, and starting the second ash removal device to remove ash from the evaporation section of the heat pipes in the sub-channels in the closed state.

[0024] In an example, the controller internally stores a temperature field distribution calculation model and an AI prediction model, the temperature field distribution calculation model calculates the temperature field distribution according to a pre-stored coupling simulation model of the rotary heat exchange assembly-heat pipe assembly and the acquired data;

[0025] The AI prediction model predicts the risk of blockage of the rotary heat exchange assembly or / and the heat pipe assembly through working parameters of a flue gas system in which the heat exchange system is located; the working parameters include one or more of a unit load rate, a sulfur content of coal powder, a denitration efficiency, a temperature history sequence of a body of the rotary heat exchange assembly, a SO3 concentration gradient, a valve angle change rate, an ambient temperature, or an ambient humidity;

[0026] The execution module controls the valves, the second ash removal device, and the first ash removal device to work based on a prediction result of the temperature field distribution calculation model and the AI prediction model.

[0027] In an example, the AI prediction model predicts a deposition thickness of ammonium bisulfate on each heat exchange unit in T hours in the future through the following formula:

[0028]

[0029] K is a reaction rate constant; R is a gas constant; Ea is an activation energy; Tw is a real-time temperature of a body of the rotary air preheater; C SO3 (t) represents a concentration of SO3 at time t; C NH3 (t) represents a concentration of NH3 at time t.

[0030] In an example, the controller further stores a heat pipe protection module, which determines whether the heat pipe is overheated according to a working temperature of a pipe wall of the heat pipe, and increases a valve of a flow dividing channel in which the heat pipe is located to increase an air intake amount of the flow dividing channel if the heat pipe is overheated.

[0031] Alternatively or / and, the controller further stores a heat pipe protection module, and further includes a driving wheel that rotates to adjust an opening degree of the door plate, and the heat pipe protection module further determines whether a rotation angle of the driving wheel is within a preset rotation angle range, and stops the driving component from working and switches a driving mode of the door plate to a manual mode if the rotation angle of the driving wheel is not within the preset rotation angle range.

[0032] In addition, the present application further provides a boiler system including a boiler and the heat exchange system.

[0033] The boiler system provided by the present application includes the heat exchange system, and thus has the technical effects of the heat exchange system. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 FIG. 1 is a structural schematic diagram of a heat exchange system according to an embodiment of the present application;

[0035] Figure 2 FIG. 2 is a structural schematic diagram of a heat exchange system according to another embodiment of the present application; Figure 1A cross-sectional view of the heat exchange system shown; the dotted arrows in the figure represent the flow direction of the flue gas, and the dashed arrows represent the flow direction of the low-temperature gas;

[0036] Figure 3 A cross-sectional view of the heat exchange system shown; the dotted arrows in the figure represent the flow direction of the flue gas, and the dashed arrows represent the flow direction of the low-temperature gas; Figure 1 A cross-sectional view of the heat exchange system shown; the dotted arrows in the figure represent the flow direction of the flue gas, and the dashed arrows represent the flow direction of the low-temperature gas;

[0037] Figure 4 A cross-sectional view of the heat exchange system shown; the dotted arrows in the figure represent the flow direction of the flue gas, and the dashed arrows represent the flow direction of the low-temperature gas; Figure 1 A cross-sectional view of the heat exchange system shown; the dotted arrows in the figure represent the flow direction of the flue gas, and the dashed arrows represent the flow direction of the low-temperature gas.

[0038] Wherein, Figures 1 to 4 The reference signs in the drawings are explained as follows:

[0039] 1 housing; 11 flue gas inlet; 12 flue gas outlet; 13 gas outlet; 14 first gas inlet; 15 second gas inlet; 2 heat pipe assembly; 21 heat pipe; 211 evaporation section; 212 condensation section; 3 rotary heat exchange assembly; 31 heat exchange unit; 101 first chamber; 102 second chamber; 103 third chamber; 4 flue gas outlet pipe; 5 primary air pipe; 6 secondary air pipe; 7 valve device; 71 valve; 72 drive wheel; 73 drive shaft; 81 first ash removal device; 82 second ash removal device; 9 partition; 20 spacer; 201 plate body structure; 202 support block. DETAILED DESCRIPTION

[0040] In view of the technical problem that the ABS adhered in the air preheater causes the air preheater heat exchange surface to be blocked, the present inventors have conducted a large amount of research and found that: the ABS is in a hard solid state below 147℃, is in a viscous liquid state between 147℃ and 250℃, and the viscosity is greater as the temperature decreases, and is in a gaseous state when the temperature is higher than 250℃. According to the form of the ABS changing with the temperature, the ABS exists in three forms in the flue gas at the tail of the boiler: at the inlet of the air preheater, the temperature is 280-360℃, at which the ABS is in a gaseous state; the temperature entering the three-bin rotary air preheater is 160℃-300℃, at which the ABS changes from a gaseous state to a liquid state as the temperature decreases, so the ABS is in a gas-liquid coexistence state in the three-bin air preheater, and the temperature from the outlet of the air preheater to the electrostatic precipitator is <160℃, at which the ABS is in a liquid state. Since the ABS is in a liquid state between 147℃ and 250℃, and the ABS in this section region coexists with the ash in the flue gas in a space, the surface will be attached with a large amount of ash as the flue gas flows, and since the liquid ABS has strong viscosity, after being attached with a large amount of ash, the ABS presents a viscous and gel-like ash form.

[0041] From the above analysis, it can be seen that when the ABS presents liquid strong viscosity, it is still in the operating range of the rotary air preheater, and with the operation of the rotary air preheater, the ABS will gradually entrap the ash in the flue gas and adhere to the air preheater, resulting in the blockage of the entire air preheater heat exchange surface.

[0042] On the premise of the above research findings, the present inventors further explored and proposed a technical solution capable of alleviating the blockage of the ABS to the air preheater heat exchange surface, which to some extent reduces the power consumption of the induced draft fan, reduces the system resistance, and further improves the stability and safety of the operation of the coal-fired unit.

[0043] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present application, the embodiments of the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0044] Please refer to Figures 1 to 4 , Figure 1 for a structural schematic diagram of a heat exchange system provided in an embodiment of the present application; Figure 2 for Figure 1 a cross-sectional view of the heat exchange system shown; Figure 3 for Figure 1 another cross-sectional view of the heat exchange system shown; Figure 4 for Figure 1 a schematic diagram of the door plate, drive wheel and partition plate and other components in the heat exchange system shown.

[0045] The embodiments of the present application provide a boiler system, which comprises a boiler and a heat exchange system, wherein the heat exchange system is mainly used for heat exchange between the boiler flue gas and the boiler inlet air, and the boiler inlet air comprises primary air or / and secondary air.

[0046] In the embodiments of the present application, the heat exchange system comprises a shell 1, the inside of the shell 1 comprises a first chamber 101, a second chamber 102 and a third chamber 103, the first chamber 101 and the second chamber 102 are arranged side by side and isolated in the horizontal direction and located below the third chamber 103. That is, along the flue gas flow direction, the third chamber 103 is arranged upstream of the first chamber 101 and the second chamber 102.

[0047] In the embodiment of the present application, the heat exchange system comprises a rotary heat exchange assembly 3 located in the third chamber 103, the rotary shaft of the rotary heat exchange assembly 3 is vertically arranged, and the rotary heat exchange assembly 3 comprises at least two heat exchange units 31 arranged in the circumferential direction. The cavity wall of the third chamber 103 is substantially sealed from the rotary heat exchange unit 31. The rotary heat exchange assembly 3 can be a Ljungstrom-type rotary air preheater. The rotary heat exchange assembly 3 comprises at least two heat exchange units 31, each heat exchange unit 31 is arranged in the circumferential direction, and each heat exchange unit 31 reciprocally rotates on the flue gas side and the low-temperature gas (primary air or secondary air) side through the rotation around the vertical center axis, so as to realize the heat exchange between the flue gas and the low-temperature gas. The heat transfer element in the heat exchange unit 31 can be a metal sheet or other material with good thermal conductivity.

[0048] In the embodiment of the present application, the heat exchange system further comprises a heat pipe assembly 2, the heat pipe assembly 2 comprises a plurality of heat pipes, each heat pipe comprises a condensation section 212 and an evaporation section 211, the condensation section 212 is located in the second chamber 102, and the evaporation section 211 is located in the first chamber 101; the first chamber 101 is a channel for the flue gas to flow, and the second chamber 102 is in communication with the primary air duct 5 and the secondary air duct 6 of the shell.

[0049] In the embodiment of the present application, the shell 1 further comprises a flue gas inlet 11, a gas outlet 13, a flue gas outlet 12 and a gas inlet, the flue gas inlet 11 and the gas outlet 13 are located above the rotary heat exchange assembly 3, the flue gas inlet 11 can communicate the flue gas outlet 12 through the heat exchange channel of part of the heat exchange unit 31 and the first chamber 101, and the gas inlet can communicate the gas outlet 13 through the second chamber 102 and the heat exchange channel of part of the heat exchange unit 31. The flue gas outlet 12 is arranged on the flue gas outlet pipe 4 of the shell.

[0050] In the heat exchange system of the present application, the rotary heat exchange assembly 3 and the heat pipe assembly 2 are arranged at the same time, the high-temperature flue gas first passes through the heat exchange unit 31 of the rotary heat exchange assembly 3 and exchanges heat with the primary air or secondary air heated by the heat pipe assembly 2, the flue gas after the heat exchange of the rotary heat exchange assembly 3 enters the first chamber to heat the medium in the evaporation section 211 of each heat pipe, and the temperature is further reduced, the heated medium in the heat pipe enters the condensation section 212 located in the second chamber 102 and exchanges heat with the primary air or secondary air from the air duct, thereby heating the primary air or secondary air, and the heated primary air or secondary air exchanges heat with the high-temperature flue gas in the third chamber 103.

[0051] From the above description, in the embodiment of the present application, the temperature of the low-temperature gas (primary air or secondary air) entering the rotary heat exchange assembly 3 can be improved by the heat pipe assembly 2, so as to improve the outlet flue gas temperature of the rotary heat exchange assembly 3 and reduce the problem of ammonium bisulfate adhesion and blockage in the rotary heat exchange assembly 3. At the same time, due to the high-efficiency heat exchange characteristics of the rotary heat exchange assembly 3, the overall heat exchange efficiency of the heat exchange system is relatively high.

[0052] In the embodiment, the first chamber 101 and the second chamber 102 are isolated by the isolation body 20, which includes a support block 202 and a plate structure 201. The support block 202 and the plate structure 201 are arranged along the flue gas flow direction. The thickness of the support block 202 in the horizontal direction is greater than the thickness of the plate structure 201. The rotary heat exchange assembly 3 is partially supported on the support block 202. The plate structure 201 has a relatively small volume, which can reduce the space occupation and facilitate reducing the overall weight of the heat exchange system. The overall thickness of the support block 202 is relatively large, which can provide stable support for the rotary heat exchange assembly 3.

[0053] In the embodiment, the support block 202 can have a hollow structure to reduce the overall weight of the heat exchange system. The support block 202 also has a flow guide slope to improve the smoothness of the flue gas flow, which facilitates the flue gas to fully fill the first chamber and fully exchange heat with the heat pipes.

[0054] In the embodiment, an example is shown in which the shell 1 can simultaneously connect the primary air pipe and the secondary air pipe. Specifically, the second chamber 102 includes a first sub-chamber and a second sub-chamber arranged in the horizontal direction. The gas inlet includes a first gas inlet 14 and a second gas inlet 15. The first sub-chamber is connected to the first gas inlet 14, and the second sub-chamber is connected to the second gas inlet 15. The upper ends of the first sub-chamber and the second sub-chamber are connected to the gas outlet through the heat exchange channels in the rotary heat exchange assembly 3. In this embodiment, the shell 1 can simultaneously connect two air pipes, which has high flexibility in use.

[0055] In the embodiment, the second chamber 102 is divided into multiple sub-flow channels by the partition plate 9. The gas inlet and the third chamber 103 are connected through the sub-flow channels. The valve 71 is arranged to adjust the opening degree of each sub-flow channel. At least one heat pipe 21 is arranged in each sub-flow channel. The valve 71 can have various forms. In one example, the valve 71 is a door plate installed at the inlet position of the sub-flow channel. The door plate has a connecting end portion which is rotatably connected to the partition plate 9 or the shell 1. Under the action of the driving component, the door plate can rotate relative to the connecting end portion to adjust the opening degree of the sub-flow channel. That is, the valve 71 can adjust the low-temperature gas entering the sub-flow channel between completely closing the sub-flow channel and completely opening the sub-flow channel.

[0056] In addition to the valve 71, the valve device 7 can also include a driving wheel 72 and a driving shaft 73. The driving wheel 72 is located outside the shell, and the driving wheel 72 drives the door plate to rotate through the driving shaft 73. The driving wheel 72 can be driven by an electric or hydraulic component, or it can be manually driven.

[0057] When the door plate is retracted, it is parallel to the flow direction of the primary and secondary air, and when the door plate is fully opened, it is perpendicular to the flow direction of the primary and secondary air, so that the corresponding flow channel area can be effectively isolated from the primary and secondary air.

[0058] In the embodiment, the heat exchange system further comprises a controller. The controller can control the state of each valve 71 so that the current state and the working temperature of at least one heat exchange unit 31 of the flue gas heat exchange are within a preset temperature range. The preset temperature range can be a temperature range in which ammonium bisulfate is least likely to deposit, for example, the preset temperature range is higher than or equal to 160 DEG C.

[0059] In the embodiment, the second chamber 102 is divided into several flow channels, each flow channel has one or more heat pipes 21, and the amount of low-temperature gas entering the flow channel can be adjusted by controlling the opening degree of the flow channel valve 71. When the opening degree of the valve 71 is small or closed, the amount of low-temperature gas in the flow channel is small or no low-temperature gas, and the temperature of the heat pipe 21 corresponding to the flow channel will rise, so that the surface-attached ammonium bisulfate can be heated and melted.

[0060] Furthermore, the infrared measurement technology is used to locate the problem of vacuum degree drop of the heat pipe in a certain area, which affects the normal operation of the heat pipe. The flow channel in the area where the heat pipe 21 is located is closed, at this time the valve 71 and the partition plate 9 together form a closed space with the heat pipe corresponding to the flow channel, and only hot flue gas flows through the evaporation section 211. At this time, the primary and secondary air will not flow through the space, and the flue gas side heats the entire heat pipe 21. Through the monitoring of the infrared technology, when the entire heat pipe is heated to be close to the flue gas, the heat pipe head is opened, and the non-condensable gas in the heat pipe is discharged. The heat pipe can be repaired online, so that the vacuum degree is restored, and the heat pipe does not need to be replaced, thereby reducing the consumption of manpower and material resources.

[0061] In the embodiment, the heat exchange system further comprises a second ash removal device 82 and a first ash removal device 81. The second ash removal device 82 and the first ash removal device 81 can be located inside the first chamber 101. The first ash removal device 81 is located above the heat pipe assembly 2 and below the rotary heat exchange assembly 3, and is used for removing ash from the rotary heat exchange assembly 3. The second ash removal device 82 can be located below the heat pipe assembly 2 and is used for removing ash from the evaporation section 211 of each heat pipe in the heat pipe assembly 2. The second ash removal device 82 and the first ash removal device 81 can be spray ash removal devices, that is, each device comprises a spray pipe, and the spray pipe sprays liquid to remove ash from the surface of the heat pipe or the surface of the heat exchange unit 31. Of course, the second ash removal device 82 and the first ash removal device 81 can also be ultrasonic ash removal devices.

[0062] By adjusting the state of each valve 71, the number of heat pipes in the heat pipe assembly 2 can be adjusted, and the inlet primary and secondary air temperature of the rotary heat exchange assembly 3 can be flexibly adjusted. When the inlet primary and secondary air temperature of the rotary heat exchange assembly 3 is 50-55℃, the outlet flue gas temperature of the rotary heat exchange assembly 3 can be stably maintained at about 160℃, and the gel-like ash formed by the combination of ammonium bisulfate and dust can be easily cleaned.

[0063] The specific method is as follows: through type selection calculation, it is confirmed that the maximum heat exchange area required when the outlet flue gas temperature of the rotary heat exchange assembly 3 reaches 160℃ under the minimum load of the unit is ensured, and this is taken as the actual heat exchange area of the heat pipe assembly 2. When the load of the unit increases, the air volume of the unit increases, the flue gas volume increases, and the inlet flue gas temperature of the rotary heat exchange assembly 3 increases. At this time, in order to maximize the heat exchange performance of the rotary heat exchange assembly 3, the opening of the valve 71 can be reduced to reduce the actual heat exchange area of the heat pipe assembly 2, so as to maximize the release of the heat exchange capacity of the rotary heat exchange assembly 3, and the temperature of the rotary heat exchange assembly 3 reaches or is slightly higher than 160℃, thereby eliminating the influence of ammonium bisulfate on the rotary heat exchange assembly 3; when the load of the unit decreases, the air volume of the unit decreases, the flue gas volume decreases, and the inlet flue gas temperature of the rotary heat exchange assembly 3 decreases. At this time, in order to ensure that the rotary heat exchange assembly 3 is not affected by the blockage of ammonium bisulfate, the opening of the valve 71 can be increased to increase the actual heat exchange area of the heat pipe assembly 2, so as to redistribute the temperature field between the rotary heat exchange assembly 3 and the heat pipe assembly 2, and the overall temperature field in the flue gas direction moves downward, so that the temperature interval below 147℃ moves to the periphery of the rotary heat exchange assembly 3, and the rotary heat exchange assembly 3 is not affected by the blockage of ammonium bisulfate.

[0064] Since the solidification temperature of ammonium bisulfate is 147℃, when the flue gas temperature in the area where ammonium bisulfate is located reaches 160℃, the gel-like ash formed by the combination of ammonium bisulfate and dust is ash that can be cleaned by the soot blower. The ash can be easily removed by the steam soot blower or ultrasonic soot blower provided in the system.

[0065] That is, the heat exchange system can be provided with an acquisition component for acquiring at least one working parameter of the flue gas inlet 11 pressure or the flue gas outlet 12 pressure or the working temperature of the rotary heat exchange assembly 3 in the current state, and the controller controls the opening of each valve 71 according to the parameter acquired by the acquisition component, so that the working temperature of at least one heat exchange unit 31 is in a preset temperature range. The preset temperature range can be greater than or equal to 160℃.

[0066] The controller can also start the first soot cleaning device 81 to clean the heat exchange unit 31 on the flue gas side according to the pre-stored strategy, thereby improving the heat exchange efficiency of the heat exchange unit 31.

[0067] Further, after the system runs for a period of time, the vacuum degree of the heat pipe decreases, and the heat pipe surface is still attached to a small amount of escaped ammonium bisulfate and dust in the flue gas, which affects the operation of the heat pipe. By adjusting the opening and closing state of the valve 71 of the shunt, opening the second dust removal device 82 can also eliminate this problem.

[0068] That is, the controller can also close one or more shunts according to the obtained working parameters of the heat pipe or the pre-stored strategy to make the surface temperature of the heat pipe in the first predetermined range, and open the second dust removal device 82 to at least clean the evaporation section 211 of the heat pipe inside the shunt in the closed state, thereby improving the heat exchange efficiency of the heat pipe. For example, the acquisition component can also acquire the working temperature, pressure and other parameters of the heat pipe. When the controller determines that the surface temperature of the heat pipe is greater than a predetermined value according to the acquired parameters, it can close the shunt where the heat pipe is located and open the second dust removal device 82 to clean the heat pipe. Of course, the controller can also periodically clean the heat pipe according to the pre-stored strategy.

[0069] The above heat pipe dust removal and heat exchange unit 31 dust removal can be performed periodically, and of course, when the parameters of the heat exchange system do not meet the use requirements, the dust removal can be performed again. The parameters of the heat exchange system can be the pressure of the flue gas inlet 11 and the pressure of the flue gas outlet 12 of the rotary heat exchange assembly 3. For example, when the rotary heat exchange assembly 3 is just put into operation under full load conditions, the differential pressure is about 1600 Pa. When the differential pressure of the rotary heat exchange assembly 3 is higher than 20% of the differential pressure under full load conditions when the system is put into operation and shows a continuous increase, it can be judged that the ammonium bisulfate is blocked. At this time, the system will issue a high differential pressure alarm in this area, and automatically close the primary and secondary air duct door plates in this area after a delay of an operation time (usually 30-60 seconds), and start the first dust removal device 81 to clean the heat exchange unit 31 to accelerate the falling of ammonium bisulfate. When the differential pressure of this area returns to normal, the door plate is opened and the system returns to normal operation.

[0070] In the embodiment of the application, the acquisition component and the controller can constitute a smart sensing control system, adopt a "sensing-decision-execution" three-level architecture, deeply integrate Internet of Things, edge computing and artificial intelligence technology, and realize closed-loop intelligent regulation and control of the air preheater anti-blocking. The acquisition component is the sensing layer, which can include a multi-dimensional sensor network. The multi-dimensional sensor network mainly realizes temperature monitoring of the rotary heat exchange assembly 3, pressure monitoring of each shunt of the rotary heat exchange assembly 3 and the heat pipe assembly 2, online monitoring of flue gas components (real-time monitoring of SO3 and NH3 escape amount through laser spectroscopy), and mechanical state monitoring (opening and closing angle of the valve 71).

[0071] The controller has a data preprocessing module, which mainly eliminates data noise, standardizes the collected temperature, pressure and other data, reduces the influence of invalid data on the analysis results, and then transmits the effective data to the decision layer of the controller through the industrial Internet of Things gateway.

[0072] The decision layer of the controller mainly analyzes and calculates the collected data to make predictions. The controller internally stores a temperature field distribution calculation model and an AI prediction model. The temperature field distribution calculation model calculates the temperature field distribution based on the pre-stored coupling simulation model of the rotary heat exchange assembly 3-heat pipe assembly 2 and the obtained data.

[0073] The AI prediction model predicts the risk of blockage of the rotary heat exchange assembly 3 or / and the heat pipe assembly 2 based on the working parameters of the flue gas system in which the heat exchange system is located. The AI prediction model mainly uses an LSTM neural network, including a combination model of unit load rate, coal sulfur content, denitration efficiency, rotary heat exchange assembly 3 body temperature history sequence, SO3 concentration gradient, valve 71 angle change rate, environmental temperature, and environmental humidity. The multi-objective optimization algorithm based on the above temperature field distribution calculation model and AI prediction model uses the NSGA-II (Nondominated Sorting Genetic Algorithm II) algorithm to generate an optimal solution set in three dimensions of blockage prevention, energy saving, and equipment life improvement, and feedback to the execution layer.

[0074] Through double-model honor verification, single-model failure is avoided to prevent misoperation.

[0075] The core algorithm principle is to use a "prediction-compensation-feedback" three-level control strategy with a dynamic adjustment module to achieve prediction of the blockage risk, dynamic distribution of heat pipe air preheater heat, and anti-disturbance compensation.

[0076] The execution module controls the operation of each valve 71, second ash removal device 82, and first ash removal device 81 based on the prediction results of the temperature field distribution calculation model and AI prediction model.

[0077] The AI prediction model predicts the deposition thickness of ammonium bisulfate on each heat exchange unit 31 in T hours in the future using the following formula:

[0078]

[0079] t represents the time parameter; K is the reaction rate constant; R is the gas constant; Ea is the activation energy; Tw is the real-time temperature of the rotary air preheater body; C SO3 (t) represents the concentration of SO3 at time t; C NH3 (t) represents the concentration of NH3 at time t.

[0080] Through the above formula, the ammonium bisulfate deposition thickness δ(t+1:t+T) in the future T hours can be predicted, and T can be any value, for example, T can be 1 hour, 2 hours, or more than 2 hours, for example, 10 hours, 24 hours, or 48 hours, and the like. The risk of blockage is predicted 24 hours in advance through the LSTM model, which improves the early warning capability by more than 6 times compared with the traditional threshold alarm (only 2-4 hours in advance).

[0081] In the embodiment of the application, the controller also stores a heat pipe protection module. Whether the heat pipe is overheated is determined according to the working temperature of the pipe wall of the heat pipe. If the heat pipe is overheated, the air intake of the shunt channel in which the heat pipe is located is increased. Since the air preheater of the heat pipe adopts a low-temperature gravity heat pipe, when the pipe wall of the heat pipe exceeds 300℃, the heat exchange pipe in the heat pipe is prone to overpressure, which can cause changes in the metallographic structure of the heat exchange pipe, accelerate the creep rate, and reduce the endurance strength. Therefore, when the heat pipe is overheated, the opening of the valve 71 needs to be adjusted in time to ensure that sufficient cold air enters the condensing end of the heat pipe and promote the rapid condensation and backflow of the heat pipe medium.

[0082] In addition to preventing the pipe wall of the heat pipe from overheating, the heat pipe protection module can also determine whether the torque of the drive wheel 72 is abnormal. In the process of frequent switching of the drive wheel 72, the adjustment angle of the drive wheel 72 can be too large, thereby causing abnormal torque. At this time, the safety protection mechanism is triggered to switch the adjustment mode of the drive wheel 72 from automatic adjustment to manual mode to avoid mechanical damage to the internal adjustment shutdown door plate.

[0083] That is, if the rotation angle of the drive wheel 72 exceeds the preset rotation angle range, the driving component is stopped, and the driving mode of the door plate is switched to manual mode.

[0084] The boiler system provided by the application includes the above-mentioned heat exchange system, and therefore has the above-mentioned technical effects of the heat exchange system.

[0085] In the description of the embodiments of the application, the terms “include”, “contain” or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device.

[0086] The above is only a preferred embodiment of the application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the application. These improvements and refinements should also be considered within the protection scope of the application.

Claims

1. A heat exchange system, characterized in that: The invention comprises a shell, wherein the interior of the shell comprises a first chamber, a second chamber, and a third chamber, wherein the first chamber and the second chamber are arranged side by side in isolation in a horizontal direction and are located below the third chamber; A rotary heat exchange assembly is located in the third chamber, wherein the rotary axis of the rotary heat exchange assembly is vertically arranged, and the rotary heat exchange assembly includes at least two heat exchange units arranged along the circumferential direction; a heat pipe assembly comprising a plurality of heat pipes, each of the heat pipes comprising a condensing section and an evaporating section, the condensing section being located in the second chamber, and the evaporating section being located in the first chamber; The shell also includes a smoke inlet, a gas outlet, a smoke outlet and a gas inlet. The smoke inlet and the gas outlet are located above the rotary heat exchange component. The smoke inlet can be connected to the smoke outlet through the heat exchange channel of the heat exchange unit on the smoke side and the first chamber. The gas inlet can be connected to the gas outlet through the second chamber and part of the heat exchange channel of the heat exchange unit.

2. The heat exchange system according to claim 1, characterized in that: The rotary heat exchange assembly comprises an isolator, wherein the first chamber and the second chamber are isolated by the isolator, the isolator comprises a supporting block and a plate structure connected along the flue gas flow direction, the thickness of the supporting block in the horizontal direction is greater than the thickness of the plate structure, and the rotary heat exchange assembly is partially supported by the supporting block; Alternatively / and, the second chamber includes a first sub-chamber and a second sub-chamber arranged in a horizontal direction, the gas inlet includes a first gas inlet and a second gas inlet, the first sub-chamber is connected to the first gas inlet, the second sub-chamber is connected to the second gas inlet, and the upper ends of the first sub-chamber and the second sub-chamber can be connected to the gas outlet through the heat exchange channel in the rotary heat exchange assembly.

3. The heat exchange system according to claim 1 or 2, characterized in that: The second chamber is divided into at least two branch channels by a partition, and the gas inlet and the third chamber are both able to communicate with each of the branch channels; the heat exchange system further includes a valve capable of adjusting the opening of each of the branch channels, and each of the branch channels is provided with at least one heat pipe; The heat exchange system further includes a controller, which can control the opening of each valve so that the operating temperature of at least one of the heat exchange units on the flue gas side is within a preset temperature range.

4. The heat exchange system according to claim 3, characterized in that: It also includes an acquisition component for acquiring at least one of the flue gas inlet pressure, flue gas outlet pressure or operating temperature of the heat exchange unit in the current state; The controller controls the opening of each valve according to the parameters acquired by the acquisition component, so that the operating temperature of the heat exchange unit on the flue gas side is within a preset temperature range.

5. The heat exchange system according to claim 4, characterized in that: It also includes a first dust cleaning device for cleaning each of the heat exchange units; The controller can also start the first cleaning device to clean the at least one heat exchange unit on the flue gas side according to the parameters obtained by the obtaining component or according to a pre-stored strategy.

6. The heat exchange system according to claim 5, characterized in that: Also included is a second cleaning device located in the first chamber, the second cleaning device being used to clean the evaporation section of each of the heat pipes; The controller can also close one or several of the branch channels according to the obtained working parameters of the heat pipe or the pre-stored strategy so that the surface temperature of the heat pipe is within a first predetermined range, and start the second cleaning device to clean at least the evaporation section of the heat pipe inside the branch channel in the closed state.

7. The heat exchange system according to claim 6, characterized in that: The controller internally stores a temperature field distribution calculation model and an AI prediction model, wherein the temperature field distribution calculation model calculates the temperature field distribution based on a pre-stored coupled simulation model of the rotary heat exchange component-heat pipe component and the acquired data; The AI ​​prediction model predicts the blockage risk of the rotary heat exchange component and / or the heat pipe component based on the operating parameters of the flue gas system in which the heat exchange system is located; the operating parameters include one or more of the following: unit load rate, pulverized coal sulfur content, denitrification efficiency, temperature history sequence of the rotary heat exchange component, SO3 concentration gradient, valve angle change rate, ambient temperature, or ambient humidity; An execution module controls the operation of each of the valves, the second cleaning device and the first cleaning device based on the prediction results of the temperature field distribution calculation model and the AI ​​prediction model.

8. The heat exchange system according to claim 7, characterized in that: The AI ​​prediction model predicts the deposition thickness of ammonium bisulfate on each heat exchange unit in the next T hours using the following formula: Wherein, K is the reaction rate constant; R is the gas constant; Ea is the activation energy; Tw is the real-time temperature of the rotary air preheater body; C SO3 (t) represents the concentration of SO3 at time t; C NH3 (t) represents the concentration of NH3 at time t.

9. The heat exchange system according to claim 4, characterized in that: The controller also stores a heat pipe protection module, which determines whether the heat pipe is over-temperature according to the working temperature of the heat pipe wall, and if over-temperature, increases the valve of the branch channel where the heat pipe is located to increase the air intake of the branch channel; Alternatively / and, the controller also stores a heat pipe protection module and also includes a driving wheel, which rotates to adjust the opening of the door panel. The heat pipe protection module further determines whether the rotation angle of the driving wheel is within a preset rotation angle range. If not, the driving component is stopped and the driving mode of the door panel is switched to manual mode.

10. A boiler system, characterized in that: The heat exchange system comprises a boiler and the heat exchange system according to any one of claims 1 to 9.

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