Cement kiln waste heat steam utilization system for autoclaved aerated concrete production

Abstract

The application discloses a cement kiln waste heat steam utilization system for autoclaved aerated concrete production, which comprises a cement kiln waste heat boiler, a temperature and pressure reducing device, a waste heat temperature rising cylinder, a temperature reducing cylinder, four autoclaves, a vacuum cylinder and a vacuum pump. The cement kiln waste heat boiler is used to provide superheated steam. One end of the temperature and pressure reducing device is connected with the cement kiln waste heat boiler through a first pipeline, and the temperature and pressure reducing device is used to reduce the temperature and pressure of the superheated steam to obtain saturated steam. The inlet end of the waste heat temperature rising cylinder is connected with the other end of the temperature and pressure reducing device through a second pipeline. The temperature reducing cylinder is connected with four outlet ends of the waste heat temperature rising cylinder through a third pipeline, a fourth pipeline, a fifth pipeline and a sixth pipeline. Therefore, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production can realize efficient utilization of the cement kiln waste heat.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cement kiln tail gas waste heat recovery, in particular to a cement kiln waste heat steam utilization system for autoclaved aerated concrete production. BACKGROUND

[0002] Autoclaved aerated concrete (AAC) is a porous lightweight silicate building product made of siliceous and calcareous materials as main raw materials, mixed with air-entraining agents and other adjusting materials, through processes such as batching, air-entraining, static stopping, cutting, and autoclaving. In the AAC production process, saturated steam with a pressure of 0.8-1.5 MPa is needed for curing, so that the constituent materials can react with each other at a high temperature to produce a series of hydration products. At present, natural gas steam boilers are mostly used to provide saturated steam, and the energy consumption of natural gas is high.

[0003] There are a large number of applications of cement kiln tail gas waste heat recovery technology at home and abroad. At present, waste heat boilers are mainly used to produce superheated steam from low-temperature waste heat tail gas, and then the superheated steam is used to drive low-parameter steam turbines to do work and generate electricity, achieving the effect of recycling and utilization. However, in the waste heat recovery process, especially in the stage of converting superheated steam into electric energy, there are heat losses and other losses.

[0004] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be regarded as an acknowledgment or any form of suggestion that it forms prior art that is publicly known in the field of the present application. SUMMARY

[0005] The present application aims to provide a cement kiln waste heat steam utilization system for autoclaved aerated concrete production, which can realize efficient utilization of cement kiln waste heat.

[0006] To achieve the above object, the application provides a cement kiln waste heat steam utilization system for autoclaved aerated concrete production, which comprises a cement kiln waste heat boiler, a temperature and pressure reducing device, a waste heat temperature raising cylinder, a temperature reducing cylinder, four autoclaves, a vacuumizing cylinder and a vacuum pump. The cement kiln waste heat boiler is used to provide superheated steam. One end of the temperature and pressure reducing device is connected with the cement kiln waste heat boiler through a first pipeline, and the temperature and pressure reducing device is used to reduce the temperature and pressure of the superheated steam to obtain saturated steam. The inlet end of the waste heat temperature raising cylinder is connected with the other end of the temperature and pressure reducing device through a second pipeline. The temperature reducing cylinder is connected with four outlet ends of the waste heat temperature raising cylinder through a third pipeline, a fourth pipeline, a fifth pipeline and a sixth pipeline respectively. The outlet end of the vacuumizing cylinder is connected with the four autoclaves through a seventh pipeline, an eighth pipeline, a ninth pipeline and a tenth pipeline respectively. The vacuum pump is connected with the inlet end of the vacuumizing cylinder through an eleventh pipeline. The middle part of the third pipeline is communicated with the middle part of the tenth pipeline, and the middle part of the fourth pipeline is communicated with the middle part of the ninth pipeline. The middle part of the fifth pipeline is communicated with the middle part of the eighth pipeline, and the middle part of the sixth pipeline is communicated with the middle part of the seventh pipeline.

[0007] In an embodiment of the application, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production further comprises a gas boiler and a gas boiler temperature raising cylinder. The inlet end of the gas boiler temperature raising cylinder is connected with the gas boiler through a twelfth pipeline, and four outlet ends of the gas boiler temperature raising cylinder are connected with the sixth pipeline, the fifth pipeline, the fourth pipeline and the third pipeline through a thirteenth pipeline, a sixteenth pipeline, a seventeenth pipeline and an eighteenth pipeline respectively.

[0008] In an embodiment of the application, a first stop valve is arranged on the first pipeline, a second stop valve and a third stop valve are arranged on the second pipeline, a fourth stop valve and a fifth stop valve are arranged on the eleventh pipeline, and a sixth stop valve and a seventh stop valve are arranged on the twelfth pipeline.

[0009] In an embodiment of the application, the temperature and pressure reducing device comprises a water tank, a pressure reducing valve, a first cooling water pipeline, a regulating valve, a first water pump, two ninth stop valves, a third cooling water pipeline and a throttle valve. The water tank is used to provide cooling water. The pressure reducing valve is installed on the first pipeline. One end of the first cooling water pipeline is connected with the second pipeline and located behind the pressure reducing valve. One end of the regulating valve is connected with the other end of the first cooling water pipeline, and the other end of the regulating valve is connected with the water tank through a second cooling water pipeline. The first water pump is installed on the second cooling water pipeline. The two ninth stop valves are installed on the second cooling water pipeline and located on the two sides of the first water pump respectively. The two ends of the third cooling water pipeline are connected with the second cooling water pipeline respectively, and the two ends of the third cooling water pipeline are located outside the two ninth stop valves respectively. The throttle valve is installed on the third cooling water pipeline.

[0010] In an embodiment of the present application, the temperature and pressure reducing device further comprises a fourth cooling water pipe, a second water pump and two tenth stop valves. Two ends of the fourth cooling water pipe are connected with the second cooling water pipe respectively, one end of the fourth cooling water pipe is located between one ninth stop valve and one end of the third cooling water pipe, and the other end of the fourth cooling water pipe is located between another ninth stop valve and the other end of the third cooling water pipe. The second water pump is installed on the fourth cooling water pipe. And the two tenth stop valves are installed on the fourth cooling water pipe respectively and are located on two sides of the second water pump respectively.

[0011] In an embodiment of the present application, the temperature and pressure reducing device further comprises a first check valve and a first filter. The first check valve is installed on the second cooling water pipe and is located between one ninth stop valve and the first water pump. And the first filter is installed on the second cooling water pipe and is located between another ninth stop valve and the first water pump.

[0012] In an embodiment of the present application, the temperature and pressure reducing device further comprises a second check valve and a second filter. The second check valve is installed on the fourth cooling water pipe and is located between one tenth stop valve and the second water pump. And the second filter is installed on the fourth cooling water pipe and is located between another tenth stop valve and the second water pump.

[0013] In an embodiment of the present application, each autoclave has a blowdown port, and the blowdown ports of the four autoclaves are gathered on the main blowdown pipe through the blowdown pipe.

[0014] In an embodiment of the present application, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production further comprises a first spring safety valve and a second spring safety valve. The first spring safety valve is installed on the second pipe and is located behind the first cooling water pipe. And the second spring safety valve is installed on the gas-fired boiler.

[0015] In an embodiment of the present application, after the autoclave is closed, the corresponding stop valve at the vacuum pumping cylinder of the autoclave is opened, and the fourth stop valve and the fifth stop valve are opened at the same time, and the vacuum pump is opened after the fourth stop valve and the fifth stop valve are opened, and the vacuum pumping operation is performed.

[0016] Compared with the prior art, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to the present application can realize efficient utilization of the cement kiln waste heat. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of the cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application;

[0018] Figure 2 is Figure 1 is an enlarged structural schematic view of a part of the structure in

[0019] Figure 3 is a structural schematic view of a temperature and pressure reducing device of a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application;

[0020] Figure 4 is another part of the structure in Figure 1 is an enlarged structural schematic view of a part of the structure in

[0021] Figure 5 is a principle line frame schematic view of a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application.

[0022] Explanation of Main Reference Numerals:

[0023] 1 - cement kiln waste heat boiler, 2 - temperature and pressure reducing device, 3 - first pipe, 4 - waste heat temperature raising cylinder, 5 - second pipe, 6 - temperature reducing cylinder, 7 - third pipe, 8 - fourth pipe, 9 - fifth pipe, 10 - sixth pipe, 11 - autoclave, 12 - vacuum extraction cylinder, 13 - seventh pipe, 14 - eighth pipe, 15 - ninth pipe, 16 - tenth pipe, 17 - vacuum pump, 18 - eleventh pipe, 19 - gas boiler, 20 - gas boiler temperature raising cylinder, 21 - twelfth pipe, 22 - thirteenth pipe, 23 - first stop valve, 24 - second stop valve, 27 - fifth stop valve, 31 - water tank, 32 - pressure reducing valve, 33 - first cooling water pipe, 34 - regulating valve, 35 - second cooling water pipe, 36 - first water pump, 37 - ninth stop valve, 38 - third cooling water pipe, 39 - throttle valve, 40 - fourth cooling water pipe, 41 - second water pump, 42 - tenth stop valve, 43 - first check valve, 44 - first filter, 45 - second check valve, 46 - second filter, 48 - first spring safety valve, 50 - third check valve, 51 - softened water heat exchanger, 52 - fourteenth pipe, 53 - fifteenth pipe, 54 - sixteenth pipe, 55 - seventeenth pipe, 56 - eighteenth pipe. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0025] Unless otherwise clearly indicated, throughout the specification and claims, the term "comprise" or variations such as "comprises" or "comprising" will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements.

[0026] Figure 1 is a schematic diagram of the overall structure of a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application. Figure 2 is Figure 1 is a schematic diagram of a part of the structure in Figure 3 is a schematic diagram of a temperature and pressure reducing device of a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application. Figure 4 is Figure 1 is a schematic diagram of another part of the structure in Figure 5 is a schematic diagram of the principle line frame of a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to an embodiment of the present application.

[0027] As shown in Figures 1 to 5 , a cement kiln waste heat steam utilization system for autoclaved aerated concrete production according to a preferred embodiment of the present application comprises a cement kiln waste heat boiler 1, a temperature and pressure reducing device 2, a waste heat temperature raising cylinder 4, a temperature reducing cylinder 6, four autoclaves 11, a vacuumizing cylinder 12, and a vacuum pump 17. The cement kiln waste heat boiler 1 is used to provide superheated steam. One end of the temperature and pressure reducing device 2 is connected to the cement kiln waste heat boiler 1 through a first pipeline 3, and the temperature and pressure reducing device 2 is used to reduce the temperature and pressure of the superheated steam, thereby obtaining saturated steam. The inlet end of the waste heat temperature raising cylinder 4 is connected to the other end of the temperature and pressure reducing device 2 through a second pipeline 5. The temperature reducing cylinder 6 is connected to the four outlet ends of the waste heat temperature raising cylinder 4 through a third pipeline 7, a fourth pipeline 8, a fifth pipeline 9, and a sixth pipeline 10, respectively. The outlet end of the vacuumizing cylinder 12 is connected to the four autoclaves 11 through a seventh pipeline 13, an eighth pipeline 14, a ninth pipeline 15, and a tenth pipeline 16, respectively. The vacuum pump 17 is connected to the inlet end of the vacuumizing cylinder 12 through an eleventh pipeline 18. The middle part of the third pipeline 7 is connected to the middle part of the tenth pipeline 16, and the middle part of the fourth pipeline 8 is connected to the middle part of the ninth pipeline 15. The middle part of the fifth pipeline 9 is connected to the middle part of the eighth pipeline 14, and the middle part of the sixth pipeline 10 is connected to the middle part of the seventh pipeline 13. The number of the autoclaves 11 is only used for illustration, and the present application does not limit the number of the autoclaves 11.

[0028] In an embodiment of the present application, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production further comprises a gas-fired boiler 19 and a gas-fired boiler temperature raising steam cylinder 20. The inlet end of the gas-fired boiler temperature raising steam cylinder 20 is connected to the gas-fired boiler 19 through a twelfth pipeline 21, and the four outlet ends of the gas-fired boiler temperature raising steam cylinder 20 are respectively connected to the sixth pipeline 10, the fifth pipeline 9, the fourth pipeline 8 and the third pipeline 7 through a thirteenth pipeline 22, a sixteenth pipeline 54, a seventeenth pipeline 55 and an eighteenth pipeline 56 respectively.

[0029] In an embodiment of the present application, a first stop valve 23 is arranged on the first pipeline 3, a second stop valve 24 and a third stop valve are arranged on the second pipeline 5, a fourth stop valve and a fifth stop valve 27 are arranged on the eleventh pipeline 18, and a sixth stop valve and a seventh stop valve are arranged on the twelfth pipeline 21.

[0030] In an embodiment of the present application, the temperature and pressure reducing device 2 comprises a water tank 31, a pressure reducing valve 32, a first cooling water pipeline 33, a regulating valve 34, a first water pump 36, two ninth stop valves 37, a third cooling water pipeline 38 and a throttling valve 39. The water tank 31 is used to provide cooling water. The pressure reducing valve 32 is installed on the first pipeline 3. One end of the first cooling water pipeline 33 is connected to the second pipeline 5 and located behind the pressure reducing valve 32. One end of the regulating valve 34 is connected to the other end of the first cooling water pipeline 33, and the other end of the regulating valve 34 is connected to the water tank 31 through a second cooling water pipeline 35. The first water pump 36 is installed on the second cooling water pipeline 35. The two ninth stop valves 37 are respectively installed on the second cooling water pipeline 35 and respectively located on the two sides of the first water pump 36. The two ends of the third cooling water pipeline 38 are respectively connected to the second cooling water pipeline 35, and the two ends of the third cooling water pipeline 38 are respectively located outside the two ninth stop valves 37. The throttling valve 39 is installed on the third cooling water pipeline 38.

[0031] In an embodiment of the present application, the temperature and pressure reducing device 2 further comprises a fourth cooling water pipeline 40, a second water pump 41 and two tenth stop valves 42. The two ends of the fourth cooling water pipeline 40 are respectively connected to the second cooling water pipeline 35, one end of the fourth cooling water pipeline 40 is located between one of the ninth stop valves 37 and one end of the third cooling water pipeline 38, and the other end of the fourth cooling water pipeline 40 is located between the other of the ninth stop valves 37 and the other end of the third cooling water pipeline 38. The second water pump 41 is installed on the fourth cooling water pipeline 40. The two tenth stop valves 42 are respectively installed on the fourth cooling water pipeline 40 and respectively located on the two sides of the second water pump 41.

[0032] In an embodiment of the present application, the temperature and pressure reducing device 2 further comprises a first check valve 43 and a first filter 44. The first check valve 43 is installed on the second cooling water pipeline 35 and located between a ninth stop valve 37 and the first water pump 36. The first filter 44 is installed on the second cooling water pipeline 35 and located between another ninth stop valve 37 and the first water pump 36.

[0033] In an embodiment of the present application, the temperature and pressure reducing device 2 further comprises a second check valve 45 and a second filter 46. The second check valve 45 is installed on the fourth cooling water pipeline 40 and located between a tenth stop valve 42 and the second water pump 41. The second filter 46 is installed on the fourth cooling water pipeline 40 and located between another tenth stop valve 42 and the second water pump 41.

[0034] In an embodiment of the present application, each autoclave 11 has a blowdown port, and the blowdown ports of the four autoclaves 11 are connected to a main blowdown pipeline through a blowdown pipeline.

[0035] In an embodiment of the present application, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production further comprises a first spring safety valve 48 and a second spring safety valve 49. The first spring safety valve 48 is installed on the second pipeline 5 and located behind the first cooling water pipeline 33. The second spring safety valve is installed on the gas-fired boiler 19.

[0036] In an embodiment of the present application, after the autoclave 11 is closed, the corresponding stop valve of the vacuum pumping cylinder 12 of the autoclave 11 is opened, and the fourth stop valve and the fifth stop valve 27 are opened at the same time. When the fourth stop valve and the fifth stop valve 27 are opened, the vacuum pump 17 is opened to perform the vacuum pumping operation. The third check valve 50 is installed on the first cooling water pipeline 33.

[0037] In an embodiment of the present application, the softened water heat exchanger 51 is connected to the cement kiln waste heat boiler 1 through a fourteenth pipeline 52 and connected to the gas-fired boiler 19 through a fifteenth pipeline 53. The fourteenth pipeline 52 and the fifteenth pipeline 53 are provided with an adjusting valve 34. The superheated steam of the cement kiln waste heat boiler 1 can preheat the softened water in the softened water heat exchanger 51 of the gas-fired boiler 19, thereby reducing the heat required for heating the water in the gas-fired boiler 19.

[0038] In practical applications, the requirements of autoclaved aerated concrete production for steam are as follows: AAC production process needs to carry out autoclaved steam curing for aerated concrete blank, only after curing at a certain temperature and for a sufficient time, the blank can complete necessary physical and chemical changes, thereby generating strength. In theory, the hydrothermal synthesis reaction can be carried out above 174.5 degrees Celsius, however, considering the heat transfer characteristics of autoclaved aerated concrete in the autoclave and production efficiency, the steam used in AAC production process should be saturated steam with a pressure above 1.2 MPa. The scale of cement kiln waste heat power generation is related to the waste heat amount of the system, generally, the waste heat amount depends on the production scale and production process of cement, generally, the waste heat recovery of pure waste heat power generation system of a cement enterprise is divided into two parts: one is the waste heat of exhaust gas at the outlet of preheater at the kiln tail; the other is the waste heat of exhaust gas at the outlet of cooler at the kiln head, through the heat exchange recovery of a large amount of low-grade waste heat of exhaust gas at the outlet of the kiln head and the kiln tail by a waste heat boiler, superheated steam is generated to drive a steam turbine to realize the conversion of heat energy to mechanical energy, thereby driving a generator to emit electric energy. Through investigation, the pressure of superheated steam at the outlet of the waste heat boiler of some cement enterprises is 1.2 MPa, the steam can be directly used for AAC production after temperature reduction by a temperature reduction device, the pressure of superheated steam at the outlet of the waste heat boiler of some cement enterprises is less than 1.2 MPa, the steam is reduced in temperature to saturated steam by a temperature reduction device, the saturated steam is introduced into the autoclave 11 through the steam cylinder of the waste heat boiler, and can be used in the early stage of autoclaved curing of AAC, when the pressure in the autoclave 11 is certain, the inlet valve of the steam cylinder of the waste heat boiler is closed, the inlet valve of the temperature rising steam cylinder 20 of the gas boiler is opened, and the pressure of the autoclave 11 is increased to above 1.2 MPa by the steam generated by the gas boiler 19.

[0039] The cement kiln waste heat steam utilization system for autoclaved aerated concrete production of the application utilizes the steam of the waste heat boiler of a cement enterprise for the production of autoclaved aerated concrete. The superheated steam (pressure: 0.9-1.4 MPa; temperature: 290-400 DEG C; flow: 15 t / h) for waste heat power generation is reduced in pressure by the pressure reducing valve 32 in the temperature and pressure reduction device 2, the temperature of the superheated steam is reduced by the temperature reduction water, the superheated steam is converted into saturated steam (pressure: 0.9-1.35 MPa; temperature: 195 DEG C; flow: 15 t / h) required in the autoclaved curing stage of autoclaved aerated concrete products, and the high efficient utilization of the waste heat of the cement kiln is realized. In use, the specific process is as follows:

[0040] 1, after the autoclave is closed after entering the autoclave, the corresponding stop valve at the autoclave vacuum cylinder 12 is opened, and the main stop valve of the vacuum cylinder 12 and the upper end stop valve of the vacuum pump 17 are opened, the stop valve is opened, the vacuum pump 17 is opened, and the vacuum operation is carried out. By adjusting the opening degree of the stop valve, 25 min is extracted to-0.06 MPa. After the vacuum extraction is completed, the upper end stop valve of the vacuum pump 17, the main stop valve of the vacuum cylinder 12 and the corresponding stop valve at the autoclave vacuum cylinder 12 are closed;

[0041] 2, after the end of the vacuum warming operation: open the waste heat boiler rear stop valve, open the water pump and the corresponding stop valve, the temperature and pressure sensor before the pressure reducing valve 32 opening degree adjustment, and according to the temperature opening water regulating valve 34, pressure reducing valve 32 and regulating valve 34 completely open, open the pressure reducing device rear stop valve, waste heat warming cylinder 4 main inlet valve and the corresponding warming kettle stop valve (the stop valve opening degree needs to be slowly opened), at this time the device before and after the temperature, pressure sensor real-time monitoring, and according to the temperature and pressure conditions to adjust the pressure reducing valve 32, regulating valve 34 opening degree. According to the temperature rising operation system, if the temperature rising cylinder and the pressure reducing device 2 end pressure flat when the waste heat warming cylinder 4 corresponding kettle stop valve is closed, the gas boiler 19 outlet stop valve, gas boiler warming cylinder 20 inlet stop valve is opened, when the pressure in the cylinder and the pressure in the autoclave 11 is flat, the cylinder outlet stop valve is opened. Continue to warm the autoclave 11. If 2-3 autoclaves are warmed at the same time, the same is true. After warming to 1.3 MPa, the corresponding kettle stop valve of the warming cylinder is closed, and the constant temperature is carried out.

[0042] 3, the operation of the sewage: in the process of warming up to 0.3 MPa and 0.5 MPa when the pressure in the kettle is opened, the exhaust valve is opened for five minutes to discharge the sewage. When the pressure in the kettle is reduced to 0.3 MPa during the cooling process, the exhaust valve is continuously opened until the kettle door is opened.

[0043] 4, the operation of the cooling: open the corresponding kettle stop valve of the cooling cylinder 6, open the air exhaust stop valve, and slowly cool down. If there are still autoclaves to be warmed up at this time, the exhaust operation can be carried out by opening the stop valve of the cooling cylinder 6 of the autoclave to be cooled and opening the stop valve of the cooling cylinder 6 of the autoclave to be warmed up. When the pressure in the cooling autoclave reaches 0.5 MPa and the pressure in the warming autoclave reaches 0.35 MPa, the stop valve of the cooling cylinder 6 is closed to stop the exhaust, and the warming operation is started according to the warming operation process. At this time, if there are still autoclaves to be warmed up, the exhaust can be continued by using the pressure reducing autoclave, and after the balance is reached again, the remaining steam in the pressure reducing autoclave is exhausted through the air exhaust of the cooling cylinder 6.

[0044] In summary, the cement kiln waste heat steam utilization system for autoclaved aerated concrete production of the present application can realize efficient utilization of the waste heat of the cement kiln, and the superheated steam of the waste heat boiler of the cement kiln can be used to preheat the softened water of the softened water heat exchanger, thereby reducing the heat required for heating the water in the gas boiler 19.

[0045] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. A cement kiln waste heat steam utilization system for autoclaved aerated concrete production, characterized in that, The application relates to a cement kiln waste heat boiler for providing superheated steam; a temperature and pressure reducing device, one end of which is connected with the cement kiln waste heat boiler through a first pipeline, and the temperature and pressure reducing device is used for reducing the temperature and pressure of the superheated steam to obtain saturated steam; a waste heat temperature and pressure increasing cylinder, an inlet end of which is connected with the other end of the temperature and pressure reducing device through a second pipeline; a temperature reducing cylinder, which is connected with four outlet ends of the waste heat temperature and pressure increasing cylinder through a third pipeline, a fourth pipeline, a fifth pipeline and a sixth pipeline respectively; four autoclaves; a vacuumizing cylinder, outlet ends of which are connected with the four autoclaves through a seventh pipeline, an eighth pipeline, a ninth pipeline and a tenth pipeline respectively; a vacuum pump, which is connected with an inlet end of the vacuumizing cylinder through an eleventh pipeline; a gas boiler; and a gas boiler temperature and pressure increasing cylinder, an inlet end of which is connected with the gas boiler through a twelfth pipeline, and four outlet ends of the gas boiler temperature and pressure increasing cylinder are connected with the sixth pipeline, the fifth pipeline, the fourth pipeline and the third pipeline through a thirteenth pipeline, a sixteenth pipeline, a seventeenth pipeline and an eighteenth pipeline respectively; wherein the middle part of the third pipeline is communicated with the middle part of the tenth pipeline, and the middle part of the fourth pipeline is communicated with the middle part of the ninth pipeline; wherein the middle part of the fifth pipeline is communicated with the middle part of the eighth pipeline, and the middle part of the sixth pipeline is communicated with the middle part of the seventh pipeline; wherein a first stop valve is arranged on the first pipeline, a second stop valve and a third stop valve are arranged on the second pipeline, a fourth stop valve and a fifth stop valve are arranged on the eleventh pipeline, and a sixth stop valve and a seventh stop valve are arranged on the twelfth pipeline; wherein after the autoclave inlet door is closed, the corresponding stop valve of the vacuumizing cylinder of the autoclave is opened, and the fourth stop valve and the fifth stop valve are simultaneously opened, and the vacuum pump is started to perform vacuumizing operation after the fourth stop valve and the fifth stop valve are opened. The temperature and pressure reducing device comprises a water tank for providing cooling water; a pressure reducing valve which is installed on the first pipeline; a first cooling water pipeline, one end of which is connected with the second pipeline and located behind the pressure reducing valve; an adjusting valve, one end of which is connected with the other end of the first cooling water pipeline, and the other end of which is connected with the water tank through a second cooling water pipeline; a first water pump which is installed on the second cooling water pipeline; two ninth stop valves which are installed on the second cooling water pipeline and located on the two sides of the first water pump respectively; a third cooling water pipeline, two ends of which are connected with the second cooling water pipeline respectively and located on the outer sides of the two ninth stop valves respectively; and a throttle valve which is installed on the third cooling water pipeline. The temperature and pressure reducing device further comprises ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 1, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ 3. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 2, characterized in that, ​ A fourth cooling water pipe, two ends of which are connected with the second cooling water pipe respectively, one end of the fourth cooling water pipe is located between one of the ninth stop valves and one end of the third cooling water pipe, and the other end of the fourth cooling water pipe is located between the other of the ninth stop valves and the other end of the third cooling water pipe; A second water pump installed on the fourth cooling water pipe; and Two tenth stop valves installed on the fourth cooling water pipe respectively and located on two sides of the second water pump respectively.

4. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 3, characterized in that, The desuperheating and pressure reducing device further comprises: A first check valve installed on the second cooling water pipe and located between one of the ninth stop valves and the first water pump; and A first filter installed on the second cooling water pipe and located between the other of the ninth stop valves and the first water pump.

5. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 4, characterized in that, The desuperheating and pressure reducing device further comprises: A second check valve installed on the fourth cooling water pipe and located between one of the tenth stop valves and the second water pump; and A second filter installed on the fourth cooling water pipe and located between the other of the tenth stop valves and the second water pump.

6. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 3, characterized in that, Each of the autoclaves has a blowdown port, and the blowdown ports of the four autoclaves are converged to a main blowdown pipe through a blowdown pipe.

7. The steam utilization system of cement kiln waste heat for autoclaved aerated concrete production according to claim 2, characterized in that, Further comprising: A first spring safety valve installed on the second pipe and located behind the first cooling water pipe; and A second spring safety valve installed on the gas-fired boiler. ​

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