Treatment and recovery system for vented waste gas of coal mill

Abstract

The utility model discloses a coal mill blow-down waste gas treatment and recovery system which comprises a coal mill, a dust remover, a circulating fan, an inert gas generator, a coal mill blow-down pipe, a heat exchange recovery device, a separation device and a screw compressor which are sequentially communicated, the screw compressor is communicated with a deaerator, and the heat exchange recovery device is communicated with a settling separation device. According to the system, zero emission of emptying waste gas of the coal mill can be realized, emission of nitrogen oxides and solid particles in an original process is eliminated, and recycling of waste heat of the emptying waste gas is realized.

Description

Technical Field

[0001] The utility model relates to the field of heat recovery in chemical production, in particular to a processing and recovery system for exhaust gas discharged from a coal mill. Background Art

[0002] The existing coal mill system includes a raw coal bunker, a coal mill, a bag dust collector, a circulating fan, and an inert gas generator; the circulating air is used to separate the water vapor in the pulverized coal and provide power for the coal mill system; the water vapor in the coal mill system is discharged into the atmosphere through the coal mill vent regulating valve and the vent outlet.

[0003] The exhaust gas from the coal mill contains 30mg / m³ nitrogen oxides, 8.5mg / m³ solid particles, 30mg / L nitrogen oxides, a discharge pressure of 2kpa, and a temperature of about 110°C. Chemical companies usually operate multiple coal mills at the same time, and the total exhaust gas emissions average 11,500 Nm3 / h.

[0004] Under the current environmental situation, the direct emission of nitrogen oxides and particulate matter in the exhaust gas from the coal mill is not conducive to the environmental protection management of the coal mill system; at the same time, the waste heat of the exhaust gas from the mill cannot be completely recovered, resulting in energy loss in the system. Summary of the invention

[0005] In view of the above problems, the utility model discloses a processing and recovery system for coal mill venting waste gas, which can achieve zero emission of coal mill venting waste gas, eliminate the emission of nitrogen oxides and solid particles in the original process, and realize the recovery and utilization of waste heat of the venting waste gas.

[0006] A treatment and recovery system for waste gas discharged from a coal mill comprises a circulation treatment system and a recovery treatment system, wherein the circulation treatment system comprises a coal mill, a dust collector, a circulation fan, and an inert gas generator which are connected in sequence, and the outlet of the inert gas generator is connected back to the coal mill; the recovery treatment system comprises a coal mill vent pipe, a heat exchange recovery device, a separation device, a screw compressor, and a deaerator which are connected in sequence, the coal mill vent pipe is connected to the circulation fan, and the heat exchange recovery device is connected to a sedimentation separation device.

[0007] Preferably, the inlet of the coal mill is connected to the outlet of the inert gas generator, and the air outlet of the circulating fan is connected to the inlet of the inert gas generator. The combustible gas in the circulating treatment system undergoes a combustion reaction in the inert gas generator to remove the combustible gas in the system. An oxygen analyzer is provided between the dust collector and the circulating fan to monitor the inert environment of the coal mill system. The coal mill is provided with an outlet regulating valve to control the system pressure and keep it normally open.

[0008] Preferably, the shell side of the heat exchange recovery device is connected to the coal mill vent pipe, and the tube side of the heat exchange recovery device is connected to the refrigerant delivery pipe. The vent exhaust gas entering the shell side is subjected to countercurrent contact heat exchange with the refrigerant in the tube side, so that the waste heat of the mill vent can be partially recovered, and the remaining low-potential energy steam is used as the refrigerant after the temperature is raised for subsequent system production. The condensate of the mill vent exhaust gas after cooling is discharged to the sedimentation separation device.

[0009] Preferably, the heat exchange recovery device is connected to the sedimentation separation device through a sewage pipeline to perform real-time discharge to avoid system blockage.

[0010] Preferably, a heat exchange baffle is provided inside the heat exchange recovery device, and the refrigerant passes through the shell-side baffle to increase the heat exchange area for heat exchange.

[0011] Preferably, the dust collector is a bag dust collector, and an explosion-proof plate is provided on the top of the bag dust collector to ensure that the system overpressure can be safely discharged.

[0012] Preferably, the refrigerant is desalted water.

[0013] Preferably, the compressor inlet is connected to the separation device, and the low-potential steam at the heat exchanger outlet is pressurized and heated by a screw compressor after impurities are separated, and then enters the deaerator for recovery.

[0014] Beneficial Effects

[0015] 1. This system thoroughly optimizes the coal mill exhaust gas venting process through heat recovery and material separation, eliminates exhaust gas venting, and achieves environmental benefits. It is a new process method and environmental protection measure for exhaust gas recycling.

[0016] 2. The system increases the heat of the exhaust gas discharged from the coal mill. The desalted water after temperature increase meets the working conditions of the post-production system. At the same time, the low-potential steam after heat exchange can still be fully recovered. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the implementation mode of the utility model, the drawings required for use in the implementation mode will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is the overall structure diagram of the utility model;

[0019] In the figure, 1. coal mill; 2. dust collector; 3. circulating fan; 4. inert gas generator; 5. heat exchange recovery device; 6. sedimentation separation device; 7. coal mill vent pipe; 8. separation device; 9. screw compressor; 10. deaerator; 11. refrigerant delivery pipe; 12. oxygen analyzer. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and or combinations thereof.

[0022] like Figure 1 As shown, the utility model discloses a processing and recovery system for exhaust gas discharged from a coal mill. The system connects a coal mill 1 to an inert gas generator 4, firstly introduces an inert gas into the coal mill, so that the circulating gas of the coal mill system undergoes combustion reaction in the inert gas generator to reduce the oxygen content of the circulating gas. A dust collector 2 is connected to a circulating fan 3, and an oxygen content analyzer 12 is arranged in the pipeline to ensure that the coal mill system is in an inert environment and to perform real-time monitoring. The pulverized coal and circulating air in the coal mill are introduced into the dust collector 2 under the power of the circulating fan to achieve air-powder separation, and a vent regulating valve is arranged to control the pressure of the coal mill system and keep it normally open, and the vent ports of multiple coal mills are merged, and the heat is aggregated and collected in a heat exchange recovery device 5. At the same time, a refrigerant delivery pipe 11 is connected to the other end of the heat exchange recovery device, and a refrigerant medium is introduced into the heat exchange recovery device 5 to perform reverse heat exchange with the exhaust gas discharged from the coal mill in the heat exchange recovery device. The exhaust gas discharged from the coal mill is in liquid form after being cooled and condensed, and is discharged to the sedimentation separation device 6 for clean recovery.

[0023] The air inlet of the coal mill 1 is connected to the outlet of the inert gas generator 4, and the air outlet of the coal mill is connected to the dust collector 2, which is a bag dust collector with an explosion-proof plate on the top to ensure that the system pressure overpressure can be safely discharged. After the coal mill exhaust gas is separated from the dust in the bag dust collector, the inert gas is returned to the inert gas generator 4 through the air outlet of the bag dust collector to provide power for the circulation of the coal mill system. The circulating gas of the coal mill system is burned in the inert gas generator to reduce the oxygen content of the circulating gas, and is monitored in real time by the oxygen analyzer 12 to ensure that the coal mill system is an inert environment. A venting regulating valve is provided to control the pressure of the coal mill system and is kept open to avoid high negative pressure in the system, which may cause damage to the explosion-proof plate of the dust collector.

[0024] The heat exchange recovery device includes a tube side and a shell side covering the outside of all the tube sides. A baffle is arranged inside to increase the reaction area. The shell side is connected to the coal mill vent pipe 7. The tube side of the heat exchange recovery device is connected to the refrigerant pipeline 11. The venting waste gas entering the shell side is countercurrently contacted with the refrigerant in the tube side for heat exchange, which can partially recover the waste heat of the mill venting. The refrigerant after temperature increase is used for subsequent system production. The mill venting waste gas is cooled and condensed into liquid, and discharged to the sedimentation separation device through the sewage pipeline. The condensed coal mill venting waste gas condensate is recovered and reused to achieve clean treatment. Real-time discharge is carried out to avoid system blockage. The refrigerant used here is 30°C desalted water.

[0025] The refrigerant passes through the shell baffle to increase the heat exchange area for heat exchange.

[0026] A separation device is set at the compressor inlet. The low-potential steam at the heat exchanger outlet is separated from impurities, pressurized and heated by the screw compressor, and then enters the deaerator for recovery.

[0027] The above description is only the preferred implementation of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A treatment and recovery system for exhaust gas from coal mill, It is characterized in that The invention comprises a circulation treatment system and a recovery treatment system, wherein the circulation treatment system comprises a coal mill (1), a dust collector (2), a circulation fan (3) and an inert gas generator (4) which are connected in sequence, and the outlet of the inert gas generator (4) is connected back to the coal mill (1); the recovery treatment system comprises a coal mill vent pipe (7), a heat exchange recovery device (5), a separation device (8), a screw compressor (9) and a deaerator (10) which are connected in sequence, the coal mill vent pipe (7) is connected to the circulation fan (3), and the heat exchange recovery device (5) is connected to a sedimentation separation device (6).

2. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The inlet of the coal mill (1) is connected to the outlet of the inert gas generator (4), and the air outlet of the circulating fan (3) is connected to the inlet of the inert gas generator (4).

3. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that An oxygen analyzer (12) for monitoring the inert environment of the coal mill system is provided between the dust collector (2) and the circulating fan (3).

4. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The coal mill (1) is provided with a normally open outlet regulating valve.

5. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The shell side of the heat exchange recovery device (5) is connected to the coal mill vent pipe (7), and the pipe side of the heat exchange recovery device (5) is connected to the refrigerant delivery pipe.

6. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The heat exchange recovery device is connected to the sedimentation separation device (6) via a sewage discharge pipeline.

7. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The heat exchange recovery device (5) is internally provided with a heat exchange baffle for increasing the heat exchange area.

8. A coal mill exhaust gas treatment and recovery system according to claim 1, It is characterized in that The dust collector (2) is a bag dust collector, and an explosion-proof plate is provided on the top of the bag dust collector.

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