A system for ensuring safety and sufficiency of high-concentration VOCs waste gas combustion treatment

Abstract

The application discloses a high-concentration VOCs waste gas combustion safety and sufficiency guarantee system, which is composed of a waste gas compression storage module, a waste gas oxygen removal module, a waste gas safety and emergency emptying module, a combustion proportioning module and a interlocking control system. The waste gas compression storage module is arranged to stably transport high-concentration VOCs waste gas with large flow variation to a combustion system. The oxygen removal module and the waste gas safety and emergency emptying module are arranged to ensure that high-concentration VOCs waste gas entering a waste gas combustion device does not contain oxygen, so that the waste gas is always in an intrinsically safe state, and the risk of combustion and explosion and backfire of the waste gas in a conveying system is avoided. The combustion proportioning module is arranged to make the flow of combustion-supporting air conveyed by a fan and the combustible content in the waste gas reach a suitable proportion, so that the two can be stably combusted, and VOCs in the waste gas is fully oxidized to generate water and carbon dioxide for emission.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment, and in particular, it is a system that ensures the safety and adequacy of combustion treatment of high-concentration VOCs waste gas. Background Technology

[0002] Industries such as petrochemicals, chemicals, materials, and electronics require large quantities of volatile organic solvents, which volatilize to produce high-concentration organic waste gases, hereinafter referred to as high-concentration VOCs waste gases. Due to their large volume and high concentration, these gases are difficult to treat to meet emission standards using conventional adsorption, absorption, and biological methods. In recent years, many enterprises have adopted combustion methods for treatment, burning and decomposing VOCs gases into water and carbon dioxide for emission. This method is highly efficient, thorough, and energy-efficient. However, the concentration of high-concentration VOCs waste gases is mostly within the explosive limits, making them flammable and explosive dangerous gases. Therefore, combustion and explosion accidents are very likely to occur during the combustion treatment process, posing a great threat to the lives and property of employees and enterprises.

[0003] To ensure the safety of combustion treatment, more and more companies are installing inert gas protection in solvent storage devices. In theory, the high-concentration VOCs waste gas emitted from solvents does not contain oxygen. However, due to defects in design, construction or management, the high-concentration VOCs waste gas emitted from solvent storage devices often carries some oxygen. This leads to the safety risk of combustion and explosion when the waste gas is input into the combustion device, and cannot achieve inherent safety.

[0004] On the other hand, due to changes in solvent usage and weather conditions such as temperature, high-concentration VOCs exhaust gases often have complex and variable compositions. Different types of VOCs require different oxygen ratios for complete combustion. Existing combustion treatment technologies mostly rely on rudimentary adjustments, often resulting in imbalances in the combustion air ratio when the exhaust gas enters the combustion unit. When the oxygen supply in the combustion air is insufficient to match the oxidation requirements of high-concentration VOCs exhaust gases, incomplete combustion occurs, producing black smoke and a large amount of unburned pollutants, leading to substandard emissions and environmental pollution. Simply introducing excessive combustion air will result in excessively low combustible concentrations, preventing combustion and causing VOCs exhaust gases to escape directly. Furthermore, variations in the flow rate of high-concentration VOCs exhaust gases also pose a significant challenge to combustion treatment. Fluctuating gas volumes often lead to imbalances in the combustion air-to-exhaust gas ratio, resulting in substandard treatment. Summary of the Invention

[0005] The purpose of this invention is to provide a safety and combustion completeness assurance system for the combustion treatment of high-concentration VOCs waste gas. This system ensures the safe and stable operation of the waste gas combustion treatment equipment, avoids the risk of combustion and explosion, and ensures that the ratio of waste gas to combustion air is appropriate, so that combustion is complete, no secondary harmful substances are produced, and the exhaust gas meets emission standards.

[0006] The technical solution to achieve the purpose of this invention is as follows:

[0007] A system for ensuring the safety and adequacy of combustion treatment of high-concentration VOCs waste gas includes:

[0008] The exhaust gas compression and storage module is used to connect to the VOCs exhaust gas outlet to store and compress VOCs exhaust gas. When the VOCs exhaust gas concentration reaches the set pressure, the VOCs exhaust gas is depressurized and released.

[0009] The exhaust gas deoxygenation module is used to detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas compression and storage module. When the oxygen concentration does not reach the dangerous concentration set value, it is directly connected to the exhaust gas safety and emergency venting module; when the oxygen concentration reaches the dangerous concentration set value, the oxygen in the VOCs exhaust gas is deoxygenated.

[0010] The exhaust gas safety and emergency venting module is used to further detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas deoxygenation module. If the oxygen concentration reaches the safe range, it will enter the subsequent combustion and proportioning module for normal combustion. If the oxygen concentration still exceeds the safe range, the VOCs exhaust gas will be vented in an emergency.

[0011] The combustion ratio module is used to introduce combustion air and detect the flow rate and concentration of VOCs exhaust gas released by the exhaust gas safety and emergency venting module. Based on the flow rate and concentration of the incoming VOCs exhaust gas, it adjusts the flow rate of the combustion air and the ratio of VOCs exhaust gas. When the pressure of the exhaust gas compression and storage module is higher than the set value, the flow rate of the combustion air is increased.

[0012] The significant advantages of this invention compared to existing technologies are:

[0013] (1) By setting up the deoxygenation module and the exhaust gas safety and emergency venting module, it is ensured that the high concentration of VOCs exhaust gas entering the exhaust gas combustion device does not contain oxygen, so that the exhaust gas is always in an inherently safe state, avoiding the risk of combustion and explosion and backfire of exhaust gas in the conveying system, and greatly improving the safety of the exhaust gas combustion treatment system.

[0014] (2) Through the automatic adjustment function of the combustion ratio module, the flow rate of the combustion air delivered by the fan and the content of combustibles in the exhaust gas are made into a suitable ratio, so that the two can burn stably. The VOCs in the exhaust gas are fully oxidized to generate water and carbon dioxide for emission. There are no incomplete combustion components and secondary pollution, and the emissions are stable and meet the standards.

[0015] (3) By setting up the exhaust gas compression and storage module, high-concentration VOCs exhaust gas with large flow rate changes can be stably delivered to the combustion system, thereby ensuring the stability of combustion and making the combustion more complete. Attached Figure Description

[0016] Figure 1 This is the system schematic diagram. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0018] Combination Figure 1 The high-concentration VOCs exhaust gas combustion safety and sufficiency assurance system of this embodiment consists of several main parts: exhaust gas compression and storage module, exhaust gas deoxygenation module, exhaust gas safety and emergency venting module, combustion ratio module, and interlock control system.

[0019] The compression storage module includes an online pressure monitoring instrument 1, a high-pressure conveying fan 2, a check valve 4, an exhaust gas compression storage tank 5, a compression storage tank pressure monitoring instrument 3, a safety pressure relief valve 6, a high-pressure exhaust gas shut-off valve 7, and an exhaust gas pressure reducing valve 9.

[0020] The online pressure monitoring instrument 1, high-pressure conveying fan 2, check valve 4, and waste gas compression storage tank 5 are connected in sequence. The waste gas compression storage tank 5 is equipped with a compression storage tank pressure monitoring instrument 3 and a safety pressure relief valve 6. The outlet of the waste gas compression storage tank 5 is connected in sequence to the high-pressure waste gas shut-off valve 7 and the waste gas pressure reducing valve 9.

[0021] The exhaust gas deoxygenation module includes a first oxygen content real-time monitor 10, an oxygen-free circuit shut-off valve 12, an oxygen-rich circuit shut-off valve 8, and a deoxygenation device 14.

[0022] The exhaust gas pressure reducing valve 9 is divided into two branches, connected to the oxygen-free circuit shut-off valve 12 and the oxygen-rich circuit shut-off valve 8 respectively. The oxygen-rich circuit shut-off valve 8 is connected to the deaerator 14. The outlet of the deaerator 14 and the outlet pipeline of the oxygen-free circuit shut-off valve 12 merge and are then connected to the exhaust gas safety and emergency venting module. The deaerator 14 is equipped with a deaerator temperature detector 13.

[0023] The exhaust gas safety and emergency venting module includes a second real-time oxygen content monitor 11 and an emergency venting shut-off valve 18; the combustion ratio module includes an online pressure monitoring instrument 15, an exhaust gas high-precision regulating valve 16, an exhaust gas online flow monitoring instrument 17, an online VOCs concentration real-time monitoring device 22, a combustion fan 19, a combustion air high-precision regulating valve 20, a combustion air flow online monitoring instrument 21, an exhaust gas flame arrester 23, a long-burning flare 24, and a high-efficiency exhaust gas burner 25.

[0024] The second real-time oxygen content monitor 11, the online pressure monitoring instrument 15, the high-precision exhaust gas regulating valve 16, the online exhaust gas flow monitoring instrument 17, the online VOCs concentration real-time monitoring device 22, and the exhaust gas flame arrester 23 are connected in sequence and then connected to the high-efficiency exhaust gas burner 25. The permanent flame 24 is used to ignite the exhaust gas discharged from the high-efficiency exhaust gas burner 25. An emergency vent shut-off valve 18 is installed on the pipeline between the second real-time oxygen content monitor 11 and the online pressure monitoring instrument 15.

[0025] The combustion fan 19, the high-precision combustion air regulating valve 20, and the online combustion air flow monitoring instrument 21 are connected in sequence and then connected to the high-efficiency exhaust gas burner 25.

[0026] The entire system is connected to a high-concentration VOCs exhaust outlet and operates according to the following principles.

[0027] Before the system starts working, the torch 24 is ignited and kept running continuously. The exhaust gas combustion fan 19 is started and the high-precision regulating valve 20 is opened to the working opening to purge the furnace. The purging is carried out for a certain period of time to ensure that there is no gas accumulation in the furnace. After the purging is completed, the high-concentration VOCs exhaust gas is introduced into the system.

[0028] The high-pressure conveying blower 2 automatically adjusts its frequency based on the pressure value fed back by the online pressure monitoring instrument 1 at the front end, ensuring that the pressure value at the front end of the blower remains in a set negative pressure state. This allows the intermittently generated and fluctuating exhaust gas from upstream to be stably drawn into the exhaust gas compression storage tank 5 at the rear end of the blower for storage. When the exhaust gas pressure in the exhaust gas compression storage tank 5 reaches the set value, the high-pressure exhaust gas shut-off valve 7 at the rear end of the tank opens. The exhaust gas passes through the pressure reducing valve 9 to reduce the pressure to the working pressure. The oxygen content in the exhaust gas is detected by the first real-time oxygen content monitor 10. The control system makes a judgment based on the interlock 2. If the exhaust gas contains no oxygen or contains only trace amounts of oxygen, the oxygen-free path shut-off valve 12 opens, and the exhaust gas directly enters the safety and emergency venting module. It is then detected again by the second real-time oxygen content monitor 11 to confirm that the oxygen content is within the safe value (if it exceeds the safe value, an emergency venting will be performed). When the shut-off valve 18 is opened, the high-precision regulating valve 16 is opened. The exhaust gas flow monitoring instrument 17 after the regulating valve monitors the exhaust gas flow in real time, and the VOCs concentration online monitoring device 22 monitors the concentration of the exhaust gas in real time. According to the concentration and flow of the exhaust gas entering the high-efficiency exhaust gas burner 25, under the real-time monitoring of the combustion air flow online monitoring instrument 21, the control system automatically adjusts the operating frequency of the exhaust gas combustion fan 19 and the size of the combustion regulating valve 20 according to the interlock 4, so that the combustion air flow delivered by the fan and the combustibles in the exhaust gas reach a suitable ratio. The two burn stably in the high-efficiency exhaust gas burner 25. The ratio of oxygen in the combustion air to VOCs in the exhaust gas is stable at 110% to 150% of the chemical oxygen demand of its oxidation reaction. At this time, the VOCs in the exhaust gas are fully burned, generating water and carbon dioxide for emission, with no incomplete combustion components and secondary pollution.

[0029] If the oxygen content (v / v%) in the exhaust gas exceeds the danger value as detected by the first real-time oxygen content monitor 10 after being released from the compressed storage tank 5, the control system will open the oxygen supply shut-off valve 8 and close the oxygen deprivation shut-off valve 12 according to interlock 2. The exhaust gas will then enter the deoxygenation device 14 for deoxygenation. After deoxygenation, the exhaust gas will enter the exhaust gas safety and emergency venting module. At this time, the second real-time oxygen content monitor 11 will detect the oxygen content (v / v%) in the exhaust gas. If the oxygen content reaches the safe range, the exhaust gas will enter the subsequent combustion and proportioning module for normal combustion. If the oxygen content still exceeds the safe range, the control system will open the emergency venting shut-off valve 18 and close the high-precision exhaust gas regulating valve 16 to 0% according to interlock 3, and the exhaust gas will be vented in an emergency. At the same time, the system will alarm and the deoxygenating agent needs to be replaced to ensure the oxygen removal effect. This module ensures that the high-concentration VOCs exhaust gas transported by the system is always in an intrinsically safe state, avoiding the risk of combustion, explosion, and backfire of the exhaust gas in the transport system.

[0030] Because the system will only release the exhaust gas in the tank after the exhaust gas storage pressure (detected by the pressure monitoring instrument of the compression tank) reaches the set high pressure value (greater than the first high pressure setting value H1), and the release of exhaust gas will stop when the pressure in the tank is lower than a certain value (low pressure setting value L), the flow fluctuation of the high concentration VOCs exhaust gas at the system inlet will not interfere with the subsequent system of the compression tank 5. The combustion ratio module of the system can operate under appropriate pressure and flow conditions, thereby ensuring the completeness of combustion.

[0031] When the pressure value of the exhaust gas compression storage tank 5 is too high (greater than the second high pressure setting value H2, H2>H1), interlock 1 is triggered. At this time, the exhaust gas high-precision regulating valve 16 automatically opens to ensure that the pressure in the storage tank is released in time. At the same time, the control system adjusts (increases) the combustion fan 19 and the combustion regulating valve 20 according to interlock 4 to ensure complete combustion.

[0032] Temperature detectors are involved in alarm and interlocking mechanisms to prevent damage from high temperatures caused by vigorous deoxygenation reactions. When the temperature detector of the deoxygenation unit shows a temperature exceeding the warning value, it indicates that the deoxygenation reaction is vigorous and excessive heat is released. At this time, the oxygen supply shut-off valve 8 closes, the oxygen deprivation shut-off valve 12 opens, and the exhaust gas directly enters the safety and emergency venting module. The second real-time oxygen content monitor 11 then checks and confirms the oxygen content value of the exhaust gas. If the oxygen content value exceeds the standard, the control system opens the emergency venting shut-off valve 18 according to interlock 3, closes the high-precision exhaust gas regulating valve 16 to 0%, and performs emergency venting of the exhaust gas. At the same time, the system alarms.

[0033] When the online pressure monitoring instrument 15 exceeds the normal value range, it indicates that the exhaust gas pressure reducing valve 9 may be malfunctioning and has failed to adjust the exhaust gas pressure to the working pressure range. At this time, the system alarms and the exhaust gas is vented urgently, requiring maintenance personnel to troubleshoot the fault and repair the system.

[0034] In certain unpredictable extreme or malfunction situations, when the concentration and flow rate of the exhaust gas entering the high-efficiency exhaust gas burner 25 fluctuate significantly, the provision of a permanent flame can prevent the high-efficiency exhaust gas burner 25 from experiencing unstable flames or flameout, while the exhaust gas flame arrestor 23 can prevent the burner flame from flashing back to the upstream pipeline.

Claims

1. A system for ensuring the safety and adequacy of combustion treatment of high-concentration VOCs waste gas, characterized in that, include: The exhaust gas compression and storage module is used to connect to the VOCs exhaust gas outlet to store and compress VOCs exhaust gas. When the VOCs exhaust gas pressure reaches the set pressure, the VOCs exhaust gas is depressurized and released. The exhaust gas deoxygenation module is used to detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas compression and storage module. When the oxygen concentration does not reach the dangerous concentration set value, it is directly connected to the exhaust gas safety and emergency venting module; when the oxygen concentration reaches the dangerous concentration set value, the oxygen in the VOCs exhaust gas is deoxygenated. The exhaust gas safety and emergency venting module is used to further detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas deoxygenation module. If the oxygen concentration reaches the safe range, it will enter the subsequent combustion and proportioning module for normal combustion. If the oxygen concentration still exceeds the safe range, the VOCs exhaust gas will be vented in an emergency. The combustion ratio module is used to introduce combustion air and detect the flow rate and concentration of VOCs exhaust gas released by the exhaust gas safety and emergency venting module. Based on the flow rate and concentration of the incoming VOCs exhaust gas, the combustion air flow rate and the VOCs exhaust gas ratio are adjusted. When the pressure of the exhaust gas compression and storage module is higher than the set value, the flow rate of exhaust gas and combustion air is increased; The exhaust gas compression and storage module includes: Online pressure monitoring instruments are used to detect VOCs exhaust gas pressure in order to control the operating frequency of the conveyor fan; Conveyor fans are used to transport VOCs waste gas to waste gas compression and storage tanks; Waste gas compression storage tank, used to store VOCs waste gas; High-pressure exhaust gas shut-off valve, used to open or close the outlet of exhaust gas compression storage tank; Pressure reducing valve is used to reduce the pressure of VOCs exhaust gas discharged from the exhaust gas compression tank to the working pressure; The pressure monitoring instrument for the compressed storage tank is used to detect the pressure of the exhaust gas compressed storage tank. When the exhaust gas storage pressure in the exhaust gas compressed storage tank reaches the first high-pressure set value, the high-pressure exhaust gas shut-off valve is opened; when the exhaust gas storage pressure in the exhaust gas compressed storage tank is lower than a certain value, the high-pressure exhaust gas shut-off valve is closed; when the pressure of the exhaust gas compressed storage tank reaches the second high-pressure set value, the flow rate of exhaust gas and combustion air is increased through the combustion ratio module. The waste gas deoxygenation module includes: The first real-time oxygen content monitor is used to detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas compression and storage module. The oxygen supply shut-off valve is connected to the deoxygenation device. When the oxygen concentration reaches the dangerous concentration set value, the oxygen supply shut-off valve opens, and the deoxygenation device removes oxygen from the VOCs waste gas and connects the treated VOCs waste gas to the waste gas safety and emergency venting module. The oxygen-free circuit shut-off valve is connected to the exhaust gas safety and emergency venting module. When the oxygen concentration does not reach the dangerous concentration set value, the oxygen-free circuit shut-off valve opens, allowing VOCs exhaust gas to be connected to the exhaust gas safety and emergency venting module. The exhaust gas safety and emergency venting module includes: The second real-time oxygen content monitor is used to further detect the oxygen concentration in the VOCs exhaust gas released by the exhaust gas deoxygenation module. An emergency vent shut-off valve is used to vent VOCs exhaust gas in an emergency when the oxygen concentration in the VOCs exhaust gas exceeds the safe range upon further detection. The combustion ratio module includes: Online exhaust gas flow monitoring instrument, used to monitor VOCs exhaust gas flow in real time; An online VOCs concentration real-time monitoring device is used to monitor the concentration of exhaust gas entering the exhaust gas combustion head in real time; The exhaust gas precision regulating valve is used to regulate the flow rate of exhaust gas entering the exhaust gas burner. A combustion air blower is used to supply combustion air into the exhaust gas burner. An online combustion air flow monitoring instrument is used to monitor the flow rate of combustion air entering the exhaust gas burner in real time; The combustion air precision regulating valve is used to regulate the flow rate of combustion air entering the exhaust gas burner. The perpetual flame is used to pre-ignite the exhaust gas in the exhaust gas burner and maintain its continuous operation. A flame arrestor for exhaust gas is used to prevent backfire of the flame in the exhaust gas burner.

2. The system for ensuring the safety and adequacy of high-concentration VOCs waste gas combustion treatment according to claim 1, characterized in that, The exhaust gas compression storage tank is equipped with a safety pressure relief valve.

3. The system for ensuring the safety and adequacy of combustion treatment of high-concentration VOCs waste gas according to claim 1, characterized in that, The deoxygenation device is equipped with a temperature detector. When the temperature detector detects that the temperature exceeds the set warning value, the oxygen supply shut-off valve closes and the oxygen deprivation shut-off valve opens, allowing the exhaust gas to directly enter the safety and emergency venting module. If the oxygen concentration in the VOCs exhaust gas detected by the second real-time oxygen content monitor exceeds the safe value range, the emergency venting shut-off valve opens.

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