Waste gas pretreatment device and waste gas treatment system

Abstract

The waste gas pretreatment device comprises a first buffer tank and a second buffer tank which are sequentially connected, a variable-frequency booster fan is arranged on a pipeline for connecting the first buffer tank and the second buffer tank, and a cooling structure is arranged on the lower portion and / or the bottom of the first buffer tank. An air uniformizing structure is arranged in the middle of the first buffer tank, the cooling structure comprises a condensing coil, and the condensing coil is coiled on the lower portion and / or the bottom of the first buffer tank; a pressure transmitter, a temperature transmitter and a safety valve are arranged at the top of each of the first buffer tank and the second buffer tank, a flow control valve and a flow meter are arranged on an air outlet of the second buffer tank, and the flow control valve is interlocked with the flow meter. According to the utility model, the impact of instantaneous large air volume on the waste gas treatment device can be avoided, the investment and operation cost of the waste gas treatment device is reduced, the situation that the emission data of the waste gas treatment device exceeds the standard due to unstable waste gas flow is avoided, and the device is particularly suitable for treating intermittent industrial waste gas with large instantaneous air volume.

Description

Technical Field

[0001] The utility model relates to an exhaust gas pretreatment device and an exhaust gas treatment system. The exhaust gas pretreatment device has the characteristics of buffering, pressure equalization and low cost, and belongs to the technical field of exhaust gas treatment equipment. Background Art

[0002] Currently, during the synthesis of pesticide technicals, the addition of liquid feeds to chemical equipment displaces the gas phase, generating displacement waste gas. This waste gas is typically collected and aggregated in closed pipelines before entering an exhaust gas treatment device. Displacement waste gas emissions are characterized by intermittent emissions, low total volume, and high air volume. While buffer tanks are typically installed to equalize pressure, the instantaneous air volume is high. Designing an exhaust gas treatment device based on this instantaneous air volume often requires a larger design air volume to meet exhaust gas treatment requirements, resulting in high investment and operating costs. Furthermore, without an effective waste gas buffer, emission data fluctuates, easily exceeding standards. Utility Model Content

[0003] In response to the shortcomings of the existing technology, the utility model provides a waste gas pretreatment device, which includes a two-stage buffer tank. The waste gas can achieve air balance, pressure balance, buffering and other functions in the pretreatment device. For industrial waste gas with intermittent instantaneous large air volume, the impact of the instantaneous large air volume on the waste gas treatment system and the impact on emission data can be reduced, the treatment effect of the waste gas treatment system is improved, and the investment and operating costs of the waste gas treatment system are reduced.

[0004] The specific technical solutions of this utility model are as follows:

[0005] A waste gas pretreatment device comprises a first buffer tank and a second buffer tank connected in sequence, a variable frequency booster fan is provided on the pipeline connecting the first buffer tank and the second buffer tank, a cooling structure is provided at the lower part and / or bottom of the first buffer tank, and an air distribution structure is provided at the middle part of the first buffer tank, the cooling structure comprises a condensing coil, and the condensing coil is coiled at the lower part and / or bottom of the first buffer tank; a pressure transmitter, a temperature transmitter and a safety valve are provided at the top of the first buffer tank and the second buffer tank, and a flow control valve and a flow meter are provided on the air outlet of the second buffer tank, and the flow control valve is interlocked with the flow meter.

[0006] Furthermore, the wind balancing structure is a wind balancing plate.

[0007] Furthermore, an air inlet is provided at the bottom or lower portion of the first buffer tank, and an air outlet is provided at the top, and the air outlet is connected to the second buffer tank.

[0008] Furthermore, the booster fan is interlocked with the pressure transmitter of the first buffer tank to stabilize the pressure of the first buffer tank at the designed value. The booster fan and the pressure transmitter installed on the first buffer tank are interlocked through electrical signals.

[0009] Furthermore, a condensate discharge port is provided at the bottom of the first buffer tank, and the condensate discharge port is connected to the condensate temporary storage device.

[0010] Furthermore, the bottom of the second buffer tank is provided with a sewage outlet and / or a condensate outlet. The sewage outlet is used to discharge the condensate that does not meet the requirements in the second buffer tank to the sewage treatment device. The condensate outlet is used to discharge the condensate that meets the requirements in the second buffer tank for storage.

[0011] Furthermore, the exhaust gas is powered by the pressure inside the second buffer tank, and the flow control valve and the flow meter are interlocked through electrical signals, and the exhaust gas is discharged at the designed air volume through interlocking control.

[0012] Furthermore, the utility model also provides an exhaust gas treatment system, which includes the above-mentioned exhaust gas pretreatment device, which is connected to the exhaust gas treatment device through a main line, and a branch line is provided on the main line, and the branch line is connected to the dilution air conveying device.

[0013] Furthermore, an induced draft fan and / or an LEL concentration detector is provided on the main pipeline, and the induced draft fan and / or the LEL concentration detector is located between the junction of the branch pipeline and the main pipeline and the exhaust gas treatment device.

[0014] Furthermore, a flame arrester and a check valve are sequentially provided on the branch pipeline, and the flame arrester is connected to the dilution air conveying device.

[0015] Furthermore, the dilution air conveying device is used to provide dilution air for diluting the exhaust gas concentration. The dilution air conveying device can be a structure such as a fan, a local exhaust system, etc. that can provide a specified amount of dilution air. The structure of the local exhaust system can refer to reports in the prior art.

[0016] Furthermore, the structure of the exhaust gas treatment device can directly adopt the device disclosed in the prior art that can perform exhaust gas treatment. The present invention does not improve the structure of the exhaust gas treatment device.

[0017] The utility model has the following beneficial effects:

[0018] The waste gas pretreatment device of the present invention can buffer, equalize the pressure and equalize the air flow for the waste gas. After the waste gas is pretreated by the pretreatment device, it can be effectively buffered, which can avoid the impact of instantaneous large air volume on the waste gas treatment device, reduce the investment and operation costs of the waste gas treatment device, and avoid the emission data of the waste gas treatment device exceeding the standard due to unstable waste gas flow. It is particularly suitable for the treatment of industrial waste gas with intermittent instantaneous large air volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of the waste gas pretreatment device of the present invention.

[0020] In the figure, 1. closed pipe, 2. cooling structure, 3. condensate temporary storage device, 4. air distribution structure, 5. first buffer tank, 6. safety valve of the first buffer tank, 7. pressure transmitter of the first buffer tank, 8. temperature transmitter of the first buffer tank, 9. booster fan, 10. second buffer tank, 11. sewage outlet, 12. pressure transmitter of the second buffer tank, 13. temperature transmitter of the second buffer tank, 14. safety valve of the second buffer tank, 15. flow control valve, 16. flow meter, 17. dilution air conveying device, 18. flame arrester, 19. check valve, 20. LEL concentration detector, 21. induced draft fan, 22. exhaust gas treatment device. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solution of the present invention in conjunction with the embodiments and drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] Example 1

[0024] like Figure 1 As shown, a specific structure of the exhaust gas pretreatment device of the present invention is provided, which includes a first buffer tank 5 and a second buffer tank 10 connected in sequence. The first buffer tank and the second buffer tank are used in combination to effectively buffer the exhaust gas and play a role in pressure equalization.

[0025] The first buffer tank is a hollow structure composed of a shell. Its shape is not particularly specified and can be cylindrical, rectangular, or other shapes. The first buffer tank's air inlet is located at its bottom or lower portion, and its air outlet is located at its top. A cooling structure 2 is provided at the lower or lower portion of the first buffer tank, or both. This cooling structure condenses the exhaust gas, and volatile organic compounds (VOCs) such as toluene and ethyl acetate in the exhaust gas form condensate that accumulates at the bottom of the first buffer tank. The cooling structure can be located inside or outside the first buffer tank. An air distribution structure 4 is provided within the first buffer tank to balance the pressure and flow of the exhaust gas. The air distribution structure is located above the cooling structure and can be located in the middle or upper portion of the first buffer tank. A pressure transmitter 7 and a temperature transmitter 8 are provided at the top of the first buffer tank to monitor the exhaust gas temperature and pressure. A safety valve 6 is also provided at the top of the first buffer tank. In the event of abnormal overpressure within the tank, the safety valve opens to provide emergency relief. Industrial waste gas enters the first buffer tank from the bottom, and from bottom to top, first passes through the cooling structure to condense the gas for pre-treatment, then passes through the air equalization structure to balance the pressure and flow, and then is discharged from the outlet into the second buffer tank.

[0026] In a specific embodiment, a condensate discharge port is provided at the bottom of the first buffer tank, which is connected to the condensate temporary storage device 3. The condensate generated by the cooling structure is discharged from the condensate discharge port and enters the condensate temporary storage device.

[0027] In one specific embodiment, the cooling structure of the first buffer tank includes a condenser coil, which is coiled around the lower portion and / or bottom of the first buffer tank. Condensate or condensed gas is disposed within the condenser coil, and the condensed liquid or condensed gas is either flowing or non-flowing. The coiling method of the condenser coil is not specifically limited and may be coiled around the bottom or lower portion of the first buffer tank in various shapes.

[0028] In a specific embodiment, the air balancing structure is an air balancing plate, and the air balancing plate is transversely arranged in the first buffer tank.

[0029] In a specific embodiment, the first buffer tank may have one or more air inlets. When there is only one air inlet, the waste gas generated by industrial synthesis can be collected through multiple closed pipelines 1 and then collected together to enter the first buffer tank through the air inlet, or each closed pipeline can enter the first buffer tank through its own air inlet. When there are two or more air inlets, the waste gas generated by industrial synthesis can enter the first buffer tank through different air inlets through multiple closed pipelines.

[0030] The first and second buffer tanks are connected by a pipeline, with the first buffer tank's outlet connected to the second buffer tank's inlet. A booster fan 9 is installed on the pipeline connecting the first and second buffer tanks. The booster fan is interlocked with the first buffer tank's pressure transmitter via an electrical signal. When the pressure in the first buffer tank exceeds the design value, the booster fan discharges the air into the second buffer tank, stabilizing the pressure in the first buffer tank at the design value.

[0031] In one specific embodiment, the booster fan is a variable-frequency booster fan. It is interlocked with the pressure transmitter of the first buffer tank and operates at a variable frequency according to the pressure within the first buffer tank, maintaining the pressure at the designed value. Specifically, the pressure transmitter provides an electrical pressure signal. Through the instrumentation and control system, the booster fan automatically adjusts its operating frequency and, therefore, its speed, based on the pressure transmitter feedback signal. This, in turn, affects the pressure within the buffer tank, maintaining the set pressure within the buffer tank.

[0032] The second buffer tank is a hollow structure consisting of a shell. Its shape is not particularly restricted and can be cylindrical, rectangular, or any other shape. A pressure transmitter 12 and a temperature transmitter 13 are installed on the top of the second buffer tank to monitor the exhaust gas temperature and pressure. A safety valve 14 is also installed on the top of the second buffer tank. In the event of abnormal overpressure within the tank, the safety valve opens to provide emergency relief.

[0033] In a specific embodiment, a condensate discharge port is provided in the second buffer tank, and the condensate meeting the requirements is discharged to the condensate storage tank through the condensate discharge port.

[0034] In a specific embodiment, a sewage outlet 11 is provided at the bottom of the second buffer tank, and the condensate that does not meet the requirements is discharged to the sewage treatment device through the sewage outlet.

[0035] Furthermore, the exhaust gas maintains a constant pressure within the second buffer tank. A flow control valve 15 and a flow meter 16 are installed at the outlet of the second buffer tank to stabilize the flow rate. The exhaust gas, powered by the pressure within the second buffer tank, exits the second buffer tank through its outlet. Exhaust gas is discharged at the designed air volume through an interlocking control. Specifically, the exhaust gas is powered by the pressure within the second buffer tank, and the flow control valve opening is interlocked with the flow meter signal to control exhaust gas discharge at the set flow rate.

[0036] Example 2

[0037] The present invention also provides an exhaust gas treatment system, which includes an exhaust gas pretreatment device, an exhaust gas treatment device and a dilution air delivery device 17. The exhaust gas pretreatment device is connected to the exhaust gas treatment device through a main line, and a branch line is provided on the main line, and the branch line is connected to the dilution air delivery device.

[0038] Furthermore, the concentration of volatile organic compounds (VOCs) in the exhaust gas discharged from the exhaust pretreatment device is generally higher than the lower explosion limit (LEL). However, according to regulations, the intake air concentration of the exhaust gas treatment facility must be controlled at 25% of the lower explosion limit (25% LEL). Therefore, the exhaust gas discharged from the exhaust pretreatment device needs to be diluted before entering the exhaust gas treatment device. This dilution process is achieved by a dilution air delivery device, which delivers dilution air to the main pipeline through a branch pipeline. The dilution air and pretreated exhaust gas are mixed in the main pipeline to a concentration that meets the requirements before entering the exhaust gas treatment device.

[0039] In a specific embodiment, the gas outlet of the second buffer tank in the exhaust gas pretreatment device is connected to the exhaust gas treatment device through a main pipeline.

[0040] In a specific embodiment, an induced draft fan 21 is provided on the main line, and the induced draft fan is located between the intersection of the branch line and the main line and the exhaust gas treatment device. The dilution air provided by the dilution air conveying device is mixed with the exhaust gas discharged from the second buffer tank and then powered by the induced draft fan and discharged to the exhaust gas treatment device 22 for treatment.

[0041] In a specific embodiment, an LEL concentration detector 20 is provided on the main line. The LEL concentration detector is located between the junction of the branch line and the main line and the exhaust gas treatment device, and before the induced draft fan, to ensure that the exhaust gas concentration meets the requirements.

[0042] In a specific embodiment, a flame arrester 18 and a check valve 19 are sequentially provided on the branch pipeline, and the flame arrester is connected to the dilution air conveying device.

[0043] Furthermore, the dilution air conveying device can be a structure such as a fan, a local exhaust system, etc. that can provide a specified amount of dilution air. The structure of the local exhaust system can refer to reports in the prior art.

[0044] Furthermore, the structure of the exhaust gas treatment device can directly adopt the device disclosed in the prior art that can perform exhaust gas treatment. The present invention does not improve the structure of the exhaust gas treatment device.

[0045] Example 3

[0046] Taking the toluene waste gas from a certain workshop as an example, the process of waste gas treatment using the waste gas pretreatment system of the present invention is briefly introduced.

[0047] Exhaust gas from various process equipment on the production line is collected through closed duct 1, with a flow rate of 0-1000 m³ / h and a temperature of 40°C, before being discharged to the first buffer tank. A cooling device at the bottom of the first buffer tank pre-condenses the exhaust gas, cooling it to a temperature of 15-30°C. The condensate then enters the condensate storage device through the condensate outlet. An air equalization device is installed in the middle of the buffer tank to balance the pressure and flow of the exhaust gas. Pressure and temperature transmitters are installed at the top of the buffer tank to monitor the exhaust gas temperature and pressure, and a safety valve is provided for emergency relief in the event of an abnormality. Exhaust gas is discharged through the top of the first buffer tank and then, via a booster fan, to the second buffer tank. The booster fan is frequency-controlled and interlocked with the first buffer tank's pressure transmitter to maintain the first buffer tank's pressure at the designed value. Generally, the pressure in the first buffer tank is controlled at ≤3-5 kPa. If the pressure exceeds the set value, the booster fan is activated, discharging excess exhaust gas to the second buffer tank.

[0048] Exhaust gas is pressurized by a booster fan and discharged into a second buffer tank. The second buffer tank is equipped with a condensate outlet and / or a sewage outlet at the bottom, and a pressure transmitter and temperature transmitter at the top to monitor exhaust gas temperature and pressure. A safety valve is also provided for emergency relief in the event of an abnormality. The pressure within the second buffer tank is generally controlled between 50 and 150 kPa, and the temperature between 15 and 30°C. A flow control valve and flow meter are installed at the buffer tank outlet to stabilize the flow rate. Exhaust gas is powered by the pressure within the second buffer tank and discharged at the designed air volume, interlocked with the flow control valve opening and the flow meter signal. The air volume is generally controlled between 20 and 50 m³ / h.

[0049] The concentration of volatile organic compounds (VOCs) in the exhaust gas from the second buffer tank is generally higher than the lower explosion limit (LEL). However, according to regulations, the inlet concentration of the exhaust gas treatment device must be controlled at 25% of the lower explosion limit (25% LEL). Therefore, the exhaust gas needs to be diluted. The dilution air is collected by the local exhaust system, flows through a flame arrester and a check valve, and then mixes with the exhaust gas. The dilution air is mixed with the exhaust gas from the second buffer tank and then powered by an induced draft fan (IDF) before being discharged to the downstream exhaust gas treatment device for treatment. An LEL concentration detector is installed on the combined line before the IDF to ensure that the exhaust gas concentration meets the requirements.

[0050] In this embodiment, the exhaust gas pollutant is toluene, and the lower explosion limit is 1.2% (volume fraction). Therefore, the exhaust gas concentration is controlled to be less than 3000 ppm, and the dilution air volume is generally 500-1000 m³ / h.

Claims

1. A waste gas pretreatment device, characterized by: It includes a first buffer tank and a second buffer tank connected in sequence, a variable frequency booster fan is provided on the pipeline connecting the first buffer tank and the second buffer tank, a cooling structure is provided at the lower part and / or bottom of the first buffer tank, and an air equalization structure is provided in the middle part of the first buffer tank, the cooling structure includes a condensing coil, and the condensing coil is coiled at the lower part and / or bottom of the first buffer tank; the tops of the first buffer tank and the second buffer tank are both provided with a pressure transmitter, a temperature transmitter and a safety valve, and the air outlet of the second buffer tank is provided with a flow control valve and a flow meter, and the flow control valve is interlocked with the flow meter.

2. The exhaust gas pretreatment device according to claim 1, characterized in that: The air distribution structure is an air distribution plate.

3. The exhaust gas pretreatment device according to claim 1, characterized in that: The variable frequency booster fan and the pressure transmitter provided on the first buffer tank are interlocked.

4. The exhaust gas pretreatment device according to claim 1 or 2, characterized in that: Includes at least one of the following structures: a. The bottom or lower portion of the first buffer tank is provided with an air inlet and a top outlet; b. The bottom of the first buffer tank is provided with a condensate discharge port, which is connected to the condensate storage device; c. The bottom of the second buffer tank is provided with a sewage outlet and / or a condensate outlet.

5. An exhaust gas treatment system, characterized by: It comprises the exhaust gas pretreatment device according to any one of claims 1 to 4, wherein the exhaust gas pretreatment device is connected to the exhaust gas treatment device through a main line, a branch line is provided on the main line, and the branch line is connected to the dilution air conveying device.

6. The exhaust gas treatment system according to claim 5, characterized in that: Includes at least one of the following structures: d. An induced draft fan and / or an LEL concentration detector is installed on the main pipeline, and the induced draft fan and / or the LEL concentration detector is located between the junction of the branch pipeline and the main pipeline and the exhaust gas treatment device; e. Flame arrester and check valve are installed in sequence on the branch pipeline, and the flame arrester is connected to the dilution air delivery device.

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