An autoclaved aerated concrete sheet waste heat recovery system and control method

Abstract

The present invention relates to the technical field of recovery systems, and particularly to a waste heat recovery system for autoclaved aerated concrete slabs, which includes an autoclave, a low-pressure water preheater, a medium-pressure water preheater, a water house, a low-pressure steam regenerator, a medium-pressure steam regenerator, a heat exchanger, a mixing tank, a workshop, and a water tank; the steam inlet of the autoclave is connected to the steam exhaust port of the low-pressure steam regenerator and the steam exhaust port of the medium-pressure steam regenerator, the exhaust port of the exhausted steam of the autoclave is connected to the heat source inlet of the low-pressure steam regenerator, the heat source inlet of the medium-pressure steam regenerator, and the heat source inlet of the mixing tank, the drain port of the autoclave is connected to the heat source water inlet of the low-pressure water preheater and the heat source water inlet of the medium-pressure water preheater. By using a multi-stage heat exchanger, the waste heat resources of the exhausted steam and condensate water of the autoclave are well recovered in a cascade manner, providing new steam for the preheating and curing of other autoclaves in the autoclave group in the early stage, and reducing the heat absorption required for the steam before entering the autoclave.

Description

Technical Field

[0001] The present invention relates to the technical field of recovery systems, and more particularly to a waste heat recovery system and control method for autoclaved aerated concrete slabs. Background Art

[0002] With the continuous improvement of the requirements for the insulation performance of building envelopes in China, the consumption of autoclaved aerated concrete with good insulation performance has increased rapidly, and the number of production enterprises and production scales have also increased sharply. However, due to limitations in factors such as design, technology, management, and technical levels, at present, the vast majority of aerated concrete enterprises in China have the common problem of directly discharging a large amount of steam and condensate, resulting in serious waste of waste heat and water resources, high product energy consumption and costs. Therefore, researching and developing a new waste heat recovery process for the production process of aerated concrete, making full, reasonable and cascaded use of waste heat resources, reducing product energy consumption and costs, and improving the energy utilization efficiency and economic benefits of enterprises have very broad prospects for popularization and application and practical significance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: in order to overcome the problem that existing aerated concrete enterprises directly discharge a large amount of steam and condensate, resulting in serious waste of waste heat and water resources, high product energy consumption and costs, a waste heat recovery system and control method for autoclaved aerated concrete slabs are provided.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a waste heat recovery system for autoclaved aerated concrete slabs, including an autoclave, a low-pressure water preheater, a medium-pressure water preheater, a water house, a low-pressure steam regenerator, a medium-pressure steam regenerator, a heat exchanger, a mixing tank, a workshop, and a water tank;

[0005] The steam inlet of the autoclave is connected to the steam discharge port of the low-pressure steam regenerator and the steam discharge port of the medium-pressure steam regenerator, the exhaust steam port of the autoclave is connected to the heat source inlet of the low-pressure steam regenerator, the heat source inlet of the medium-pressure steam regenerator, and the heat source inlet of the mixing tank, and the drain port of the autoclave is connected to the heat source water inlet of the low-pressure water preheater and the heat source water inlet of the medium-pressure water preheater;

[0006] The water supply pipe of the water house is connected to the water inlet of the low-pressure water preheater and the water inlet of the medium-pressure water preheater;

[0007] The water inlet of the mixing tank is connected to the drain outlet of the low-pressure steam regenerator. The drain outlet of the medium-pressure steam regenerator is connected to the water inlet of the low-pressure steam regenerator. The mixing tank is connected to the water tank and the heat exchanger. The workshop is connected to the heat exchanger and the water tank. By using a multi-stage heat exchanger, the waste heat resources of the autoclave exhaust steam and condensate are well recovered in a cascaded manner, providing new steam for the preheating of other autoclaves in the autoclave group at the early stage, reducing the heat absorption required for the steam before entering the autoclave, greatly improving the thermal efficiency in the production process of autoclaved aerated concrete slabs, reducing the process energy consumption in the preparation process of autoclaved aerated concrete, and at the same time avoiding the impact of direct steam discharge from the autoclave on the quality decline of the slabs.

[0008] It further includes that a pressure sensor, a thermometer and a flow meter are installed on the main pipeline of the exhaust steam pipe of the autoclave. A high-pressure steam valve is installed on the branch pipeline between the exhaust steam pipe of the autoclave and the medium-pressure steam regenerator. A medium-pressure steam valve is installed on the branch pipeline between the exhaust steam pipe of the autoclave and the low-pressure steam regenerator. A low-pressure steam valve is installed on the branch pipeline between the exhaust steam pipe of the autoclave and the mixing tank.

[0009] It further includes that a flow regulating pump is installed on the main pipe of the drain pipe of the autoclave. A medium-pressure control valve is installed on the branch pipeline of the drain pipe between the autoclave and the low-pressure water preheater. A high-pressure control valve is installed on the branch pipeline of the drain pipe between the autoclave and the medium-pressure water preheater.

[0010] It further includes that the medium-pressure water preheater is connected to the medium-pressure steam regenerator.

[0011] It further includes that a first valve is installed on the pipeline between the low-pressure steam regenerator and the mixing tank. A second valve is installed on the pipeline between the heat exchanger and the mixing tank. A third valve is installed on the pipeline between the mixing tank and the water tank.

[0012] A control method for the waste heat recovery system of autoclaved aerated concrete slabs. When the autoclave is in a high-pressure state, the high-pressure control valve is opened and the medium-pressure control valve is closed; when the autoclave is in a medium-pressure state, the high-pressure control valve is closed and the medium-pressure control valve is opened; the condensate water in the autoclave is connected to the water inlet of the mixing tank through heat exchange in the low-pressure water preheater and the medium-pressure water preheater, and a thermometer and a flow meter are provided on its pipeline to monitor the temperature and flow of the condensate water after waste heat utilization.

[0013] When the autoclave is in a high-pressure state, the high-pressure steam valve is opened and the other two steam valves are closed; when the autoclave is in a medium-pressure state, the medium-pressure steam valve is opened and the other two steam valves are closed; when the autoclave is in a low-pressure state, the low-pressure steam valve is opened and the other two steam valves are closed.

[0014] Thermometers and flow meters are installed on each exhaust steam pipe to monitor the temperature and flow rate of the exhaust steam. High-pressure steam valves, medium-pressure steam valves, and low-pressure steam valves control the flow rate of the exhaust steam entering, thereby controlling the generation amount of the new steam.

[0015] When the temperature is relatively low, the second valve opens and the third valve closes. The water outlet of the mixing tank is connected to the heat exchanger through a pipeline to heat the production water. The low-temperature water after heat exchange is used as the production water in the production and ash mixing workshops. When the temperature is relatively high, the second valve closes and the third valve opens. The water outlet of the mixing tank is connected to the water tank and the production water supply in the water house. After being mixed to a certain temperature, it is used as the production water in the production and ash mixing workshops.

[0016] The beneficial effects of the present invention are as follows: An autoclaved aerated concrete slab waste heat recovery system provided by the present invention has a reasonable structural design. By using a multi-stage heat exchanger, the waste heat resources of the exhaust steam and condensate water in the autoclave are well recovered in a cascaded manner, providing new steam for the preheating of other autoclaves in the autoclave group at the early stage, reducing the heat absorption required for the steam before entering the autoclave, greatly improving the thermal efficiency in the production process of autoclaved aerated concrete slabs, reducing the process energy consumption in the preparation process of autoclaved aerated concrete, and at the same time avoiding the influence of directly discharging steam from the autoclave on the quality decline of the slabs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the drawings and embodiments.

[0018] Figure 1 is a schematic structural diagram of the present invention.

[0019] In the figure: 1. Autoclave, 2. Low-pressure water preheater, 3. Medium-pressure water preheater, 4. Water house, 5. Low-pressure steam regenerator, 6. Medium-pressure steam regenerator, 7. Heat exchanger, 8. Mixing tank, 9. Workshop, 10. Water tank, 101. Pressure sensor, 102. High-pressure steam valve, 103. Medium-pressure steam valve, 104. Low-pressure steam valve, 105. High-pressure control valve, 106. Medium-pressure control valve, 107. First valve, 108. Second valve, 109. Third valve, 201. Thermometer, 301. Flow meter, 401. Flow regulating pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Now, the present invention will be further described in detail with reference to the drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so they only show the components related to the present invention.

[0021] As Figure 1It is a schematic structural diagram of the present invention. An autoclaved aerated concrete sheet waste heat recovery system includes an autoclave 1, a low-pressure water preheater 2, a medium-pressure water preheater 3, a water room 4, a low-pressure steam regenerator 5, a medium-pressure steam regenerator 6, a heat exchanger 7, a mixing tank 8, a workshop 9, and a water tank 10. Each part is connected by pipelines to achieve heat recovery. Since the temperature required to heat the supply water into preheated water is relatively low, while a higher temperature is required to heat the preheated water into steam, separately heating the autoclave condensate and the autoclave exhaust steam for the supply water and the preheated water respectively can maximize the waste heat utilization rate;

[0022] The steam inlet of the autoclave 1 is connected to the steam exhaust outlet of the low-pressure steam regenerator 5 and the steam exhaust outlet of the medium-pressure steam regenerator 6. The exhaust steam outlet of the autoclave 1 is connected to the heat source inlet of the low-pressure steam regenerator 5, the heat source inlet of the medium-pressure steam regenerator 6, and the heat source inlet of the mixing tank 8. The drain outlet of the autoclave 1 is connected to the heat source water inlet of the low-pressure water preheater 2 and the heat source water inlet of the medium-pressure water preheater 3. The medium-pressure steam regenerator 6 and the low-pressure steam regenerator 5 use the high-pressure exhaust steam and medium-pressure exhaust steam in the autoclave 1 to heat the preheated water to generate new steam, which is used for steam addition and temperature rise during the initial pressure increase and temperature rise pre-curing of other autoclaves in the autoclave group;

[0023] A thermometer and a flowmeter are provided on the water supply pipeline of the low-pressure water preheater 2 to monitor the inlet and outlet temperatures and flow rates of the supply water. A thermometer and a flowmeter are provided on the water supply pipeline of the medium-pressure water preheater 3 to monitor the inlet and outlet temperatures and flow rates of the supply water;

[0024] A pressure sensor 101, a thermometer 201, and a flowmeter 301 are installed on the main pipeline of the exhaust steam pipe of the autoclave 1. The flowmeter 301 is used to monitor the steam volume of the generated new steam entering other autoclaves in the autoclave group. A high-pressure steam valve 102 is installed on the branch pipeline between the exhaust steam pipe of the autoclave 1 and the medium-pressure steam regenerator 6. A thermometer, a flowmeter, and a steam valve are provided on the exhaust steam pipeline to control the exhaust steam. A medium-pressure steam valve 103 is installed on the branch pipeline between the exhaust steam pipe of the autoclave 1 and the low-pressure steam regenerator 5. A low-pressure steam valve 104 is installed on the branch pipeline between the exhaust steam pipe of the autoclave 1 and the mixing tank 8. High-pressure steam valves 102, medium-pressure steam valves 103, and low-pressure steam valves 104 are provided on the pipeline between the exhaust steam outlet at the upper part of the autoclave 1 and the heat source inlets of the medium-pressure steam regenerator 6, the low-pressure steam regenerator 5, and the mixing tank 8. The steam valves are electrically connected to the control terminal;

[0025] The higher the pressure of water, the greater its specific heat capacity. Use the characteristics of high temperature and high heat of high-pressure condensate to heat the medium-pressure water supply; during the vaporization process of water, the higher the pressure, the higher the corresponding temperature. Use the high-temperature and high-pressure exhaust steam to heat the preheated water in the medium-pressure state;

[0026] A flow regulating pump 401 is installed on the main drain pipe of the autoclave 1. The flow regulating pump 401 can regulate the flow rate of high-temperature condensate to control the temperature and flow rate of the generated preheated water. A medium-pressure control valve 106 is installed on the branch drain pipe between the autoclave 1 and the low-pressure water preheater 2, and a high-pressure control valve 105 is installed on the branch drain pipe between the autoclave 1 and the medium-pressure water preheater 3;

[0027] The water supply pipe of the water room 4 is connected to the water inlet of the low-pressure water preheater 2 and the water inlet of the medium-pressure water preheater 3. The condensate heats the water supply of the water room 4 in the low-pressure water preheater 2;

[0028] The water inlet of the mixing tank 8 is connected to the drain outlet of the low-pressure steam regenerator 5. The drain outlet of the medium-pressure steam regenerator 6 is connected to the water inlet of the low-pressure steam regenerator 5. The mixing tank 8 is connected to the water tank 10 and the heat exchanger 7. The workshop 9 is connected to the heat exchanger 7 and the water tank 10.

[0029] After the first-stage waste heat recovery, the condensate and the condensate after the first-stage waste heat recovery of the exhausted steam still have a lot of heat that can be reused to heat the heating water. By using the waste heat resources of the autoclave condensate and the autoclave exhausted steam respectively, two waste heat recovery processes are set up, which can greatly reduce the geothermal loss caused by the temperature difference; the two-stage waste heat recovery can make full use of the waste heat in the condensate and the exhausted steam to improve the heat utilization rate.

[0030] According to the ambient temperature and the heating water demand at that time, if the ambient temperature is low and heating is required, the condensate in the mixing tank will enter the heat exchanger 7 for the static pre-curing of the autoclave, and after cooling, it will be used for production, such as process water for stirring, pouring, etc.; if the ambient temperature is relatively high, the condensate in the mixing tank will enter the water supply of the water tank and the water room and then be remixed to a suitable production temperature, and then sent to the workshop for mixing ash production.

[0031] The medium-pressure water preheater 3 is connected to the medium-pressure steam regenerator 6.

[0032] A first valve 107 is installed on the pipeline between the low-pressure steam regenerator 5 and the mixing tank 8. A second valve 108 is installed on the pipeline between the heat exchanger 7 and the mixing tank 8. A third valve 109 is installed on the pipeline between the mixing tank 8 and the water tank 10.

[0033] The high-pressure waste steam of the autoclave 1 is connected to the heat source steam inlet of the medium-pressure steam regenerator 6 through a pipeline, and a thermometer and a flow meter are arranged on its steam pipeline to monitor the temperature and flow rate of the high-pressure waste steam, control the flow rate of the high-pressure waste steam entering the medium-pressure steam regenerator. The high-pressure waste steam heats the medium-pressure preheated water to generate new steam, and the condensed water after heat exchange of the high-pressure waste steam enters the low-pressure steam regenerator 5 as a heat source; the water supply port of the low-pressure steam regenerator 5 is connected to the water outlet of the low-pressure water preheater 2 through a pipeline. The medium-pressure waste steam of the autoclave 1 is connected to the heat source steam inlet of the low-pressure steam regenerator 5 through a steam pipeline, and a thermometer and a flow meter are arranged on its steam pipeline to monitor the temperature and flow rate of the medium-pressure waste steam, control the flow rate of the medium-pressure waste steam entering the medium-pressure steam regenerator; both the low-pressure steam regenerator 5 and the medium-pressure steam regenerator 6 are provided with concentration sensors to detect the concentration of non-condensable gases. When the non-condensable gases exceed the concentration range, the exhaust valve opens to discharge the non-condensable gases; the steam outlets of the medium-pressure steam regenerator 6 and the low-pressure steam regenerator 5 are connected to the steam inlet of the evaporation kettle 1 through a steam pipeline, and a thermometer and a flow meter are arranged on its steam pipeline to monitor the temperature and flow rate of the new steam.

[0034] A control method for the waste heat recovery system of autoclaved steam-cured concrete slabs. Since the condensed water and waste steam at different pressures have different temperatures, setting three pressure ranges for relatively independent heat exchange can greatly reduce the heat loss caused by temperature difference and rationally utilize the waste heat resources in the condensed water and waste steam. When the autoclave 1 is in a high-pressure state of 0.7 - 1.3 MPa, the high-pressure control valve 105 opens and the medium-pressure control valve 106 closes; when the autoclave 1 is in a medium-pressure state of 0.3 - 0.7 MPa, the high-pressure control valve 105 closes and the medium-pressure control valve 106 opens; the condensed water in the autoclave 1 passes through the low-pressure water preheater 2 and the medium-pressure water preheater 3 for heat exchange and then is connected to the water inlet of the mixing tank ⑧ through a pipeline. A thermometer 201 and a flow meter 301 are arranged on its pipeline to monitor the temperature and flow rate of the condensed water after waste heat utilization.

[0035] When the autoclave 1 is in a high-pressure state, the high-pressure steam valve 102 opens and the other two steam valves close; when the autoclave 1 is in a medium-pressure state, the medium-pressure steam valve 103 opens and the other two steam valves close; when the autoclave 1 is in a low-pressure state, the low-pressure steam valve 104 opens and the other two steam valves close. Thermometers and flow meters are arranged on each waste steam exhaust pipe to monitor the temperature and flow rate of the waste steam. The high-pressure steam valve 102, the medium-pressure steam valve 103, and the low-pressure steam valve 104 control the flow rate of the waste steam entering, thereby controlling the generation amount of the new steam;

[0036] When the temperature is relatively low, the second valve 108 opens and the third valve 109 closes. The water outlet of the mixing tank 8 is connected to the heat exchanger 7 through a pipeline to heat the production water. The low-temperature water after heat exchange is used as the production water for the production and ash mixing workshop 9. When the temperature is relatively high, the second valve 108 closes and the third valve 109 opens. The water outlet of the mixing tank 8 is connected to the water tank 10 and the production water supply in the water room through a pipeline. After being mixed to a certain temperature, it is used as the production water for the production and ash mixing workshop 9.

[0037] The autoclave condensate heating water supply stage; the autoclave waste steam heating preheated water stage; the stage where the condensate after the utilization of low-pressure waste steam, waste steam waste heat and the condensate after the utilization of autoclave waste heat are mixed together to jointly heat the heating water. Since the temperature of the condensate and waste steam in the autoclave is different under different pressures, and the latent heat of vaporization of the waste steam has more heat compared with the condensate, the condensate heats the water supply to increase the water supply temperature, and the waste steam heats the preheated water to become new steam. The condensate after waste heat recovery and the condensate after the utilization of waste steam waste heat still have more heat that can be reused to heat the heating water. Separating the condensate and waste steam for waste heat recovery in the production process of pressurized concrete slabs can avoid the loss of waste heat resources caused by the decrease in energy grade. Cascade utilization of waste heat resources can greatly improve the utilization rate of waste heat and increase the steam output.

[0038] Its principle is to multi-stage utilize the waste heat resources after the autoclave cures the concrete to generate new steam for the initial temperature rise and air supplement of other autoclaves in the autoclave unit, and to heat the heating water for the heat preservation of the static curing and pre-curing chambers. The condensate in the autoclave preheats the water supply of the water room, reducing the heat in the process of heating the water to steam, which is the first-stage waste heat recovery of the autoclave condensate. Then the condensate enters the mixing tank and is mixed with other waste heat sources, and then heats the heating water in the heat exchanger 7 for the heat preservation of the pre-curing and static curing chambers, which is the second-stage waste heat recovery of the condensate. Finally, the condensate after waste heat utilization can also be used as the water for ash mixing. The waste steam in the autoclave is introduced into the steam regenerator to heat the preheated water to generate new steam, which is the first-stage waste heat recovery of the waste steam, and is used for the initial temperature rise and air supplement of other autoclaves in the unit, reducing the demand for new steam.

[0039] After the high-pressure steam is utilized, it can be introduced into the medium-pressure steam generator again to jointly heat the preheated water with the medium-pressure steam. The generated new steam is also used for the initial temperature rise and air supplement of other autoclaves in the unit. The low-pressure waste steam and the medium-high pressure waste steam condensate enter the mixing tank and are mixed with other waste heat sources to heat the heating water as the second-stage waste heat recovery.

[0040] In the above-mentioned processes, the main functions of the medium-pressure steam regenerator 6 and the low-pressure steam regenerator 5 are to heat the steam for boosting the pressure of other autoclaves 1 in the autoclave group, converting it into medium and low-pressure steam, reducing the steam consumption of the autoclaves, and improving the steam utilization efficiency. The main functions of the medium-pressure water preheater 3 and the low-pressure water preheater 2 are to preheat the feed water before entering the steam regenerator, raising its temperature. The autoclave 1 is a primary heat user, mainly using the latent heat of vaporization of steam to heat the autoclaved concrete products.

[0041] The working process of this system is as follows:

[0042] The condensate water in the autoclave 1 is respectively introduced into the medium-pressure water preheater 3 and the low-pressure water preheater 2 for preheating the medium-pressure and low-pressure water supplies. The medium and low-pressure preheated water respectively enters the medium-pressure steam regenerator 6 and the low-pressure steam regenerator 5, and under the heating of the high-pressure exhaust steam and medium-pressure exhaust steam of the autoclave 1, new medium-pressure and low-pressure steam is generated for steam curing initial pressure boosting and pre-curing of other autoclaves 1 in the autoclave unit. The exhaust steam of the autoclave 1 controls the valve steam and condensate water according to the pressure change during the exhaust process. Among them, the high-pressure exhaust steam enters the medium-pressure steam regenerator 6 to heat the medium-pressure preheated water to generate new medium-pressure steam, and after the high-pressure exhaust steam cools down, it enters the low-pressure steam regenerator 5 as the heat source for reusing the waste heat again; the medium-pressure exhaust steam enters the low-pressure steam regenerator 5 to heat the low-pressure preheated water to generate new low-pressure steam, and after the medium-pressure exhaust steam cools down and condenses, it enters the mixing tank 8. The mixing tank 8 mixes the condensate water and low-pressure exhaust steam after waste heat utilization. When the ambient temperature is relatively low and heating water is required for the insulation of the pre-curing room and the static-curing room, the condensate water in the mixing tank 8 enters the heat exchanger 7 to exchange heat with the heating water and then becomes low-temperature condensate water, and then enters the production batching workshop 9 as the production water for concrete. When the ambient temperature is relatively high and heating water is not required for static curing, the condensate water in the mixing tank 8 enters the water tank 10, and is mixed with the water supply from the water room to an appropriate temperature and then used in the production batching workshop 9.

[0043] Inspired by the above ideal embodiments of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. An autoclaved aerated concrete sheet waste heat recovery system, characterized in that, It includes an autoclave (1), a low-pressure water preheater (2), a medium-pressure water preheater (3), a water house (4), a low-pressure steam regenerator (5), a medium-pressure steam regenerator (6), a heat exchanger (7), a mixing tank (8), a workshop (9), and a water tank (10); The steam inlet of the autoclave (1) is connected to the steam exhaust outlet of the low-pressure steam regenerator (5) and the steam exhaust outlet of the medium-pressure steam regenerator (6). The exhausted steam outlet of the autoclave (1) is connected to the heat source inlet of the low-pressure steam regenerator (5), the heat source inlet of the medium-pressure steam regenerator (6), and the heat source inlet of the mixing tank (8). The drain outlet of the autoclave (1) is connected to the heat source water inlet of the low-pressure water preheater (2) and the heat source water inlet of the medium-pressure water preheater (3); The water delivery pipe of the water house (4) is connected to the water inlet of the low-pressure water preheater (2) and the water inlet of the medium-pressure water preheater (3); The water inlet of the mixing tank (8) is connected to the drain outlet of the low-pressure steam regenerator (5). The drain outlet of the medium-pressure steam regenerator (6) is connected to the water inlet of the low-pressure steam regenerator (5). The mixing tank (8) is connected to the water tank (10) and the heat exchanger (7). The workshop (9) is connected to the heat exchanger (7) and the water tank (10); A pressure sensor (101), a thermometer (201), and a flowmeter (301) are installed on the main pipeline of the exhausted steam pipe of the autoclave (1). A high-pressure steam valve (102) is installed on the branch pipeline between the exhausted steam pipe of the autoclave (1) and the medium-pressure steam regenerator (6). A medium-pressure steam valve (103) is installed on the branch pipeline between the exhausted steam pipe of the autoclave (1) and the low-pressure steam regenerator (5). A low-pressure steam valve (104) is installed on the branch pipeline between the exhausted steam pipe of the autoclave (1) and the mixing tank (8); A flow regulating pump (401) is installed on the main drain pipe of the autoclave (1). A medium-pressure control valve (106) is installed on the branch drain pipe between the autoclave (1) and the low-pressure water preheater (2). A high-pressure control valve (105) is installed on the branch drain pipe between the autoclave (1) and the medium-pressure water preheater (3); The medium-pressure water preheater (3) is connected to the medium-pressure steam regenerator (6); A first valve (107) is installed on the pipeline between the low-pressure steam regenerator (5) and the mixing tank (8). A second valve (108) is installed on the pipeline between the heat exchanger (7) and the mixing tank (8). A third valve (109) is installed on the pipeline between the mixing tank (8) and the water tank (10).

2. A control method for the waste heat recovery system of the autoclaved aerated concrete slab described in claim 1, characterized in that: When the autoclave (1) is under high pressure, the high-pressure control valve (105) is opened and the medium-pressure control valve (106) is closed; when the autoclave (1) is under medium pressure, the high-pressure control valve (105) is closed and the medium-pressure control valve (106) is opened; the condensed water in the autoclave (1) is connected to the water inlet of the mixing tank (8) through a pipeline after heat exchange in the low-pressure water preheater (2) and the medium-pressure water preheater (3), and a thermometer (201) and a flowmeter (301) are provided on the pipeline to monitor the temperature and flow rate of the condensed water after waste heat utilization; When the autoclave (1) is under high pressure, the high-pressure steam valve (102) is opened and the other two steam valves are closed; when the autoclave (1) is under medium pressure, the medium-pressure steam valve (103) is opened and the other two steam valves are closed; when the autoclave (1) is under low pressure, the low-pressure steam valve (104) is opened and the other two steam valves are closed; Thermometers and flowmeters are provided on each exhaust steam pipe to monitor the temperature and flow rate of the exhaust steam, and the high-pressure steam valve (102), the medium-pressure steam valve (103) and the low-pressure steam valve (104) control the flow rate of the exhaust steam entering, thereby controlling the generation amount of the new steam; When the temperature is relatively low, the second valve (108) is opened and the third valve (109) is closed, and the water outlet of the mixing tank (8) is connected to the heat exchanger (7) through a pipeline to heat the production water, and the heat-exchanged low-temperature water is used as the production water in the production and ash mixing workshop (9); when the temperature is relatively high, the second valve (108) is closed and the third valve (109) is opened, and the water outlet of the mixing tank (8) is connected to the water tank (10) through a pipeline and mixed with the production water supply in the water room to a certain temperature and then used as the production water in the production and ash mixing workshop (9).

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