Compression condensation and expansion refrigeration coupled waste gas pretreatment equipment

Abstract

The utility model discloses compression condensation and expansion refrigeration coupled waste gas pretreatment equipment, which belongs to the field of waste gas treatment and comprises an air compressor, a compression condensing tower and an expansion condensing tower. The condensation tower comprises a first liquid storage tank and a first condenser, the air compressor is connected with the first liquid storage tank, the air inlet end of the first condenser is connected with the first liquid storage tank, and the first condenser is used for being connected with a cooling medium; the expansion condensing tower comprises a second liquid storage tank and a second condenser, the air inlet end of the second condenser is connected with the second liquid storage tank, and the exhaust end of the first condenser is connected with the air inlet end of the second condenser or the second liquid storage tank; the exhaust end of the second condenser is connected to the cooling medium inlet end of the second condenser through a circulation pipeline, and the cooling medium outlet end of the second condenser is used for discharging pretreated waste gas. According to the utility model, waste gas can be subjected to two cooling condensation processes of high-pressure condensation and expansion cooling, so that the concentration of final exhaust is reduced under the condition that the temperature of a refrigerant is not changed.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of waste gas treatment, especially a waste gas pretreatment equipment coupled with compression condensation and expansion refrigeration. BACKGROUND

[0002] With the continuous development of China's economy and the deep adjustment of industrial structure, clean production has become a deeply rooted development concept. We see that in recent years, China has been increasing the environmental regulation, especially the regulation and investment of industrial waste gas, and has achieved remarkable results.

[0003] In the fields of pharmaceuticals, material synthesis, fine chemical industry, etc., there are a large amount of organic solvent emissions. For example, dichloromethane, methanol, ethyl acetate, methyl tert-butyl ether, etc. Taking dichloromethane as an example, a certain amount of volatilization will occur in the production, transportation and use of dichloromethane. Because dichloromethane contains chlorine element, a large amount of hydrogen chloride will be produced during combustion, and dioxin may also be produced, which has a large secondary pollution. In addition, the hydrogen chloride produced by combustion is highly corrosive at high temperatures.

[0004] The common deep treatment process of dichloromethane includes liquid nitrogen deep cooling and adsorption-desorption condensation method. The liquid nitrogen deep cooling treatment process has high energy consumption and investment, which does not meet the current double carbon policy requirements. The adsorption-desorption condensation method is the most common dichloromethane deep treatment process at present. However, the general adsorption-desorption condensation method requires that the inlet concentration of dichloromethane cannot be too high, so for high concentration waste gas, pretreatment is needed.

[0005] The common pretreatment methods include condensation and membrane method. The condensation process has low investment and operation cost and simple process, and is the most common. However, the temperature limit of the general first-stage mechanical compression refrigeration condensation is-35℃, and according to the Antoine formula calculation, the saturated concentration of dichloromethane in the gas at this time is 84g / m 3 , and the concentration of waste gas is still high, which is not suitable for adsorption-desorption condensation method. SUMMARY

[0006] In view of the problem that the concentration of waste gas after pretreatment by compression condensation is still high in the prior art, the utility model aims to provide a waste gas pretreatment equipment coupled with compression condensation and expansion refrigeration, so as to at least partially solve the above problems.

[0007] To achieve the above-mentioned purpose, the technical scheme of the utility model is as follows:

[0008] The utility model provides a kind of compressed condensation and expansion refrigeration coupling exhaust gas pretreatment equipment, including air compressor, compressed condensation tower and expansion condensation tower;The compressed condensation tower includes first liquid storage tank and first condenser, the air inlet end of the air compressor is used to connect exhaust gas source, the exhaust end of the air compressor is connected the first liquid storage tank by exhaust gas inlet pipe, the air inlet end of the first condenser is connected with the first liquid storage tank, the cooling medium inlet end of the first condenser is equipped with cooling medium inlet pipe for connecting cold source, the cooling medium outlet end of the first condenser is equipped with cooling medium outlet pipe for discharging cooling medium;The expansion condensation tower includes second liquid storage tank and second condenser, the air inlet end of the second condenser is connected with the second liquid storage tank, the exhaust end of the first condenser is connected with the air inlet end of the second condenser or with the second liquid storage tank by gas outlet pipeline;The exhaust end of the second condenser is connected to the cooling medium inlet end of the second condenser by circulation pipeline, and the cooling medium outlet end of the second condenser is connected with exhaust pipe for discharging pretreated exhaust gas.

[0009] In some preferred embodiments, the first liquid storage tank and the second liquid storage tank are both connected with liquid discharge pipes, and control valves are installed on the liquid discharge pipes.

[0010] In some preferred embodiments, branch pipes are connected to the liquid discharge pipes, and control valves are installed on the branch pipes.

[0011] In some preferred embodiments, control valves are installed on the exhaust gas inlet pipe, the cooling medium inlet pipe and the circulation pipeline.

[0012] In some preferred embodiments, temperature detection devices are installed on the gas outlet pipeline, the circulation pipeline and the exhaust pipe.

[0013] The above technical solution has the following advantages: by means of the air compressor, the compressed condensation tower and the expansion condensation tower, the exhaust gas can be cooled through high-pressure condensation and expansion cooling, so that the concentration of the final exhaust gas can be further reduced without changing the temperature of the refrigerant. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The structure of the utility model is shown in the figure.

[0015] In the figure: 1-air compressor, 2-first liquid storage tank, 3-first condenser, 4-second liquid storage tank, 5-second condenser, 101-exhaust gas inlet pipe, 102-cooling medium inlet pipe, 103-cooling medium outlet pipe, 104-gas outlet pipeline, 105-circulation pipeline, 106-exhaust pipe, 107-liquid discharge pipe, 108-control valve, 109-temperature detection device, 110-branch pipe. DETAILED DESCRIPTION

[0016] The specific embodiments of the present application will be further described below with reference to the drawings. It should be noted that the description of these embodiments is used to help understand the present application, but does not constitute a limitation on the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no conflict.

[0017] It should be noted that in the description of the present application, the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship of the structure of the present application shown in the drawings, and are only for the convenience of describing the present application. It is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0018] For "first" and "second" in the present technical solution, it is only a distinction of the same or similar structure, or the corresponding structure with similar function, not the arrangement of the importance of these structures, nor the order, or comparison, or other meanings.

[0019] In addition, unless otherwise specified and limited, the terms "mounting", "connection" should be broadly understood, for example, the connection can be fixed connection, or detachable connection, or integral connection; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium; can be the communication inside two structures. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the overall idea of the present application and the specific circumstances of the present solution.

[0020] Embodiments

[0021] A compressed condensation and expansion refrigeration coupled exhaust gas pretreatment device, as shown in Figure 1 The compressed condensation and expansion refrigeration coupled exhaust gas pretreatment device includes an air compressor 1, a compressed condensation tower and an expansion condensation tower.

[0022] The compressed condensation tower includes a first liquid storage tank 2 and a first condenser 3. The air compressor 1 is connected to the exhaust gas source through a pipeline at the air inlet end, and the exhaust gas inlet pipe 101 is connected to the upper part of the first liquid storage tank 2 at the air outlet end of the air compressor 1.

[0023] The first condenser 3 is arranged above the first liquid storage tank 2. The first condenser 3 is, for example, a shell-and-tube condenser, which has an air inlet end, an air outlet end, a cooling medium inlet end and a cooling medium outlet end. The air inlet end of the first condenser 3 faces downward and is connected to the first liquid storage tank 2. The cooling medium inlet end of the first condenser 3 is connected to a cooling medium inlet pipe 102, which is used to connect to a cooling source. The cooling medium outlet end of the first condenser 3 is provided with a cooling medium outlet pipe 103, which is used to discharge the cooling medium. Generally, the cooling medium inlet end of the first condenser 3 is located on the lower side of the cooling medium outlet end.

[0024] The expanded condensation tower comprises a second liquid storage tank 4 and a second condenser 5. The second liquid storage tank 4 has the same structure as the first liquid storage tank 2. The second condenser 5 has the same structure as the first condenser 3.

[0025] The second condenser 5 also has an air inlet end, an air outlet end, a cooling medium inlet end and a cooling medium outlet end. The second condenser 5 is arranged above the second liquid storage tank 4, and the air inlet end of the second condenser 5 faces and is connected to the second liquid storage tank 4. The air outlet end of the first condenser 3 is connected to the air inlet end of the second condenser 5 through an air outlet pipe 104, or is connected to the upper part of the second liquid storage tank 4. The air outlet end of the second condenser 5 is connected to the cooling medium inlet end of the second condenser 5 through a circulation pipe 105. The cooling medium outlet end of the second condenser 5 is connected to a waste gas discharge pipe 106, which is used to discharge the pretreated waste gas. Generally, the cooling medium inlet end of the second condenser 5 is located on the lower side of the cooling medium outlet end.

[0026] The first liquid storage tank 2 and the second liquid storage tank 4 are generally connected to a liquid discharge pipe 107, on which a control valve 108 is installed. In addition, the waste gas inlet pipe 101, the cooling medium inlet pipe 102 and the circulation pipe 105 are also provided with the control valve 108. The control valve 108 is used to control the on-off state of the related pipe, for example, a gate valve, and is generally configured as an electric valve, a solenoid valve or a pneumatic valve suitable for control.

[0027] In order to monitor the temperature of the waste gas in the related pipe, a temperature detection device 109, for example, a temperature sensor, is installed on the waste gas outlet pipe 104, the circulation pipe 105 and the waste gas discharge pipe 106.

[0028] The liquid discharge pipe 107 is generally connected to a branch pipe 110, on which the control valve 108 is also installed. Through the branch pipe 110 and the control valve 108 thereon, the staff can conveniently take samples from the corresponding liquid storage tank.

[0029] The working process of the waste gas pretreatment equipment coupled with compressed condensation and expansion refrigeration provided by the utility model is as follows:

[0030] The exhaust gas is first compressed by the air compressor 1 to a pressure of 0.15-0.3 MPa (i.e. absolute pressure), and then condensed by the first condenser 3 (e.g. cooled by a cooling medium at -30°C), a part of the exhaust gas is condensed into liquid and collected in the first liquid storage tank 2, and the remaining high-pressure exhaust gas is introduced into the expansion condensing tower through the gas outlet pipeline 104, the pressure of the high-pressure exhaust gas is reduced to 0.11 MPa due to expansion (the pressure can be adjusted according to the situation, which can be achieved by changing the flow rate of the high-pressure gas and the volume of the expansion condensing tower), the gas expansion process can be regarded as an adiabatic process, according to the first law of thermodynamics, ΔH = ΔU + W = 0, i.e. ΔU = -W, so that the second cooling of the exhaust gas can be achieved by expansion, for example, when the pressure of the exhaust gas is expanded from 0.21 MPa to 0.11 MPa, the temperature is reduced by about 38°C, which further reduces the temperature of the exhaust gas, and further condensation occurs, and the condensed liquid is stored in the second liquid storage tank 4. The exhaust gas that is not condensed in the expansion condensing tower is introduced into the cooling medium inlet end of the second condenser 5 through the circulation pipeline 105, and then discharged from the cooling medium outlet end of the second condenser 5 into the exhaust gas discharge pipeline 106, so that the expanded exhaust gas that is not condensed is not directly discharged, but is used as the cooling medium of the second condenser 5, so that the second condenser 5 maintains a low temperature environment, and the exhaust gas that enters the expansion condensing tower needs to be heat exchanged in the second condenser 5 before being discharged, so as to ensure that the finally discharged exhaust gas has a low temperature, and the saturation concentration of the exhaust gas is reduced, so as to facilitate subsequent treatment. The heat exchange efficiency is calculated as 50%, and the expansion condensing tower of the utility model can reduce the temperature of the exhaust gas with a pressure of 0.21 MPa to -45°C (part of the cold energy is consumed in the phase change), so that the final exhaust gas concentration is reduced to 20.9 g / m 3 Even if the same cooling medium is used, the utility model can cool the exhaust gas, such as dichloromethane, to 20.9 g / m 3 .

[0031] The embodiments of the utility model are described in detail in combination with the drawings, but the utility model is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirits of the utility model, and still fall within the protection scope of the utility model.

Claims

1. A waste gas pretreatment device that couples compression condensation and expansion refrigeration, characterized in that: The system includes an air compressor, a compression condenser, and an expansion condenser. The compression condenser includes a first liquid storage tank and a first condenser. The air compressor's inlet is connected to a waste gas source, and its exhaust is connected to the first liquid storage tank via a waste gas inlet pipe. The first condenser's inlet is connected to the first liquid storage tank, and its cooling medium inlet is connected to a cooling medium inlet pipe for connecting to a cold source. Its cooling medium outlet is connected to a cooling medium outlet pipe for discharging the cooling medium. The expansion condenser includes a second liquid storage tank and a second condenser. The second condenser's inlet is connected to the second liquid storage tank, and the first condenser's exhaust is connected to either the second condenser's inlet or the second liquid storage tank via an outlet pipe. The second condenser's exhaust is connected to its cooling medium inlet via a circulation pipe, and its cooling medium outlet is connected to a outlet pipe for discharging pre-treated waste gas.

2. The waste gas pretreatment equipment according to claim 1, characterized in that: Both the first and second liquid storage tanks are connected to a drain pipe, and a control valve is installed on the drain pipe.

3. The waste gas pretreatment equipment according to claim 2, characterized in that: A branch pipe is connected to the drain pipe, and a control valve is installed on the branch pipe.

4. The waste gas pretreatment equipment according to claim 1, characterized in that: Control valves are installed on the exhaust gas inlet pipe, the cooling medium inlet pipe, and the circulation pipe.

5. The waste gas pretreatment equipment according to claim 1, characterized in that: Temperature detection devices are installed on the outlet pipe, the circulation pipe, and the exhaust pipe.

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