VOC (volatile organic compound) low-emission device

Abstract

The utility model relates to the technical field of chemical equipment, in particular to a VOC (volatile organic compound) low-emission device which comprises a pretreatment unit, an adsorption and desorption unit and an RTO (regenerative thermal oxidizer), the pretreatment unit is connected with the adsorption and desorption unit; the adsorption and desorption unit is connected with the RTO; waste gas to be treated is introduced into the pretreatment unit, is pretreated by the pretreatment unit, is conveyed to the adsorption and desorption unit, is treated by the adsorption and desorption unit, is conveyed to the RTO, is combusted and is discharged. According to the VOC low-emission device, after discharged waste gas is treated by the pretreatment unit, the adsorption and desorption unit and the RTO, the waste gas can stably reach the NMHC which is less than 30mg / m < 3 > specified in the emission standard of pollutants for petrochemical industry in GB31571-2015.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical equipment, in particular to a VOC low emission device. Background Art

[0002] The waste gas generated by some chemical plant sewage treatment stations is mainly VOCs (measured in NMHC). The waste gas treatment of the existing chemical warehouse sewage treatment station is mainly treated by the "three-stage falling film absorption + first-stage water washing + second-stage activated carbon adsorption" purification system. After the waste gas is treated by the existing purification system, the NMHC emission concentration is 100mg / m 3 It is still unable to reach the NMHC<30mg / m3 stipulated in GB31571-2015 on the “Petrochemical Industry Pollutant Emission Standard”. Therefore, how to reduce the VOC content of waste gas generated by chemical plant sewage treatment stations is a technical problem that needs to be solved at present. Utility Model Content

[0003] The utility model aims at the technical problem in the prior art that waste gas generated by a sewage treatment station in a chemical plant has a high VOC content, and provides a VOC low emission device.

[0004] The technical solution of the utility model to solve the above technical problems is as follows:

[0005] A VOC low emission device comprises: a pretreatment unit, an adsorption and desorption unit and an RTO; the pretreatment unit is connected to the adsorption and desorption unit; the adsorption and desorption unit is connected to the RTO; the workshop exhaust gas to be treated is connected to the pretreatment unit, and is transported to the adsorption and desorption unit after pretreatment by the pretreatment unit, and is transported to the RTO after treatment by the adsorption and desorption unit and then discharged after combustion.

[0006] Furthermore: the pretreatment unit includes: a multi-stage falling film absorption tower and a water washing tower; the multi-stage falling film absorption tower is connected to the water washing tower, and the water washing tower is connected to the adsorption and desorption unit; the workshop waste gas to be treated is connected to the multi-stage falling film absorption tower.

[0007] Furthermore: the adsorption and desorption unit includes: a pre-adsorption pretreatment device, a wire mesh air cooler, a main fan and an adsorption and desorption device; the pre-adsorption pretreatment device is connected to the water washing tower; the pre-adsorption pretreatment device is connected to the air inlet end of the main fan through the wire mesh air cooler, and the air outlet end of the main fan is connected to the RTO through the adsorption and desorption device.

[0008] Furthermore: the adsorption and desorption unit also includes: a first array of tubes, a second array of tubes, a third array of tubes, a drying system and a recovery device; the first array of tubes, the second array of tubes, and the third array of tubes are arranged in the adsorption and desorption device; the first array of tubes, the second array of tubes, and the third array of tubes are connected in series and connected to a condensed water source; one end of the drying system is connected to the first array of tubes, and the other end of the drying system is connected to the second array of tubes; the recovery device is arranged in the adsorption and desorption device, and the recovery device is used to collect and recover the condensed substances generated by the first array of tubes, the second array of tubes, and the third array of tubes.

[0009] Furthermore: the RTO comprises: a thermal oxidation chamber, a heat storage chamber and a combustion chamber; the thermal oxidation chamber is connected to the adsorption and desorption device, and the thermal oxidation chamber is also connected to the combustion chamber through the heat storage chamber.

[0010] Furthermore: it also includes: a water washing tower and an alkali washing tower; the water washing tower is connected to the combustion chamber, and the water washing tower is connected to the alkali washing tower.

[0011] Furthermore: it also includes: an exhaust fan; the exhaust fan is arranged on the discharge channel of the alkali washing tower.

[0012] The VOC low emission device provided by the utility model has at least the following beneficial effects or advantages:

[0013] The utility model provides a VOC low emission device, wherein the pretreatment unit is connected to the adsorption and desorption unit; the adsorption and desorption unit is connected to the RTO; the waste gas to be treated is connected to the pretreatment unit, and is transported to the adsorption and desorption unit after being pretreated by the pretreatment unit, and is transported to the RTO after being treated by the adsorption and desorption unit and then discharged after being burned. The VOC low emission device can stably achieve NMHC < 30 mg / m3 as specified in GB31571-2015 on the "Petrochemical Industry Pollutant Emission Standard" after the waste gas discharged is treated by the pretreatment unit, the adsorption and desorption unit and the RTO. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of a low VOC emission device provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0015] The utility model aims at the technical problem in the prior art that waste gas generated by a sewage treatment station in a chemical plant has a high VOC content, and provides a VOC low emission device.

[0016] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] See also Figure 1 The embodiment of the utility model provides a VOC low emission device, including: a pretreatment unit, an adsorption and desorption unit and an RTO. The pretreatment unit is connected to the adsorption and desorption unit; the adsorption and desorption unit is connected to the RTO; the waste gas to be treated is connected to the pretreatment unit, and is transported to the adsorption and desorption unit after pretreatment by the pretreatment unit, and is transported to the RTO after treatment by the adsorption and desorption unit and then discharged after combustion.

[0018] The pretreatment unit includes: a multi-stage falling film absorption tower and a water washing tower; the multi-stage falling film absorption tower is connected to the water washing tower, and the water washing tower is connected to the adsorption and desorption unit; the waste gas to be treated is connected to the multi-stage falling film absorption tower. This embodiment adopts the treatment method of "three-stage multi-stage falling film absorption tower + one-stage low-temperature water washing tower", and the acidic components in the waste gas are recovered and treated by a three-stage falling film tower; the three-stage falling film tower is connected in series to treat the tail gas. The maximum treatment efficiency can reach 97.3%, and the residual HCL and CL after falling film absorption 2 It enters the water washing tower (sodium hypochlorite absorption tower) for further treatment as a pretreatment before entering the VOCs treatment equipment.

[0019] The adsorption-desorption unit includes: a pre-adsorption pretreatment device, a wire mesh air cooler, a main fan and an adsorption-desorption device; the pre-adsorption pretreatment device is connected to a water washing tower; the pre-adsorption pretreatment device is connected to an air inlet end of the main fan through a wire mesh air cooler, and an air outlet end of the main fan is connected to the RTO through the adsorption-desorption device.

[0020] The adsorption-desorption unit also includes: a first array of tubes, a second array of tubes, a third array of tubes, a drying system and a recovery device. The first array of tubes, the second array of tubes and the third array of tubes are arranged in the adsorption-desorption device; the first array of tubes, the second array of tubes and the third array of tubes are connected in series and connected to a condensed water source. One end of the drying system is connected to the first array of tubes, and the other end of the drying system is connected to the second array of tubes, and the drying system is used to dry the passing gas. The recovery device is arranged in the adsorption-desorption device, and the recovery device is used to collect and recover the condensed substances generated by the first array of tubes, the second array of tubes and the third array of tubes.

[0021] The pre-adsorption pretreatment device is used to remove high-boiling-point organic matter and high-salt inorganic matter in the waste gas. The adsorption and desorption device mainly includes two functions: one is to use CCL4-80 granular activated carbon as the adsorption material, and use the adsorption capacity of the activated carbon surface to make the waste gas contact with the porous activated carbon material with a large surface area. The pollutants in the waste gas are adsorbed on the surface of the activated carbon, so that they are separated from the gas mixture, thereby achieving the purpose of purification. The second is to adsorb a certain amount of organic solvent adsorbent material, desorb and regenerate it with saturated water vapor, and the organic solvent adsorbed on the adsorption material is blown off by the steam to form a steam mixture with the steam. The steam mixture is condensed with circulating water in the heat exchanger through the condensation system, and the condensed organic solvent aqueous solution is automatically precipitated and layered. For the activated carbon fiber recovery device, since a large amount of water remains on the activated carbon fiber core after each desorption, the presence of this water not only occupies most of the activated carbon fiber micropores, but also seriously affects the adsorption efficiency of the activated carbon fiber to organic molecules, resulting in a decrease in the equilibrium saturated adsorption amount. In addition, the temperature of the carbon fiber layer after regeneration (desorption) is generally above 100°C, which will seriously affect the adsorption efficiency of the activated carbon fiber. Therefore, an adsorption bed cooling device is added, and a vacuum pump is used for negative pressure cooling to ensure that when the next cycle of adsorption of organic waste gas occurs, the adsorption bed temperature can be reduced to below 50°C in a short time to facilitate the adsorption effect of the activated carbon fiber.

[0022] See also Figure 1 , RTO includes: thermal oxidation chamber, heat storage chamber and combustion chamber; the thermal oxidation chamber is connected to the adsorption and desorption device, and the thermal oxidation chamber is also connected to the combustion chamber through the heat storage chamber. Using the characteristics of the self-combustion of organic matter in the exhaust gas, under a certain temperature condition higher than the auto-ignition point, the gas meets turbulence and stays for a certain time to achieve complete decomposition of organic matter, and at the same time uses heat storage ceramics to recover heat. The thermal oxidation chamber is a device that heats the exhaust gas to about 780°C through the preheating chamber, and the organic matter contained in the exhaust gas in the thermal oxidation chamber is fully oxidized and decomposed, so that the oxidation temperature is maintained at about 850°C. The function of the heat storage chamber is to store part of the heat of the flue gas by the heat storage body, which is used to preheat the exhaust gas, so that the exhaust gas can be oxidized and decomposed more thoroughly when entering the furnace, and can even directly ignite the exhaust gas, which can significantly save fuel. The combustion chamber is a high-temperature oxidation decomposition of the preheated exhaust gas entering the combustion chamber, and the purified high-temperature exhaust gas is cooled by the heat storage body and discharged to meet the standards.

[0023] In a preferred embodiment provided by the utility model, it also includes: a water washing tower, an alkali washing tower and an exhaust fan; the water washing tower is connected to the combustion chamber, and the water washing tower is connected to the alkali washing tower. The exhaust fan is arranged on the discharge channel of the alkali washing tower. Since the volatile organic waste gas contains halogens, acidic waste gas will be generated after decomposition. A water washing tower and an alkali washing tower are arranged at the rear end of the RTO for terminal absorption and purification.

[0024] The VOC low emission device provided by the embodiment of the utility model has at least the following beneficial effects or advantages:

[0025] The VOC low emission device provided by the embodiment of the utility model has a pretreatment unit connected to an adsorption and desorption unit; the adsorption and desorption unit is connected to an RTO; the waste gas to be treated is connected to the pretreatment unit, and is transported to the adsorption and desorption unit after pretreatment by the pretreatment unit, and is transported to the RTO after treatment by the adsorption and desorption unit and then discharged after combustion. The VOC low emission device can stably achieve NMHC < 30 mg / m3 as specified in GB31571-2015 on the "Petrochemical Industry Pollutant Emission Standard" after the waste gas discharged is treated by the pretreatment unit, the adsorption and desorption unit and the RTO.

[0026] In the description of the present utility model, it should be noted that the terminology nouns in the various embodiments, such as words indicating directions such as "upper", "lower", "front", "back", "left", "right", etc., are only for simplifying the description of the positional relationship based on the drawings in the specification, and do not mean that the referred elements and devices must be operated according to the specific directions and specified operations and methods and structures in the specification. Such directional nouns do not constitute limitations on the present utility model.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances.

[0028] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A VOC low emission device, characterized in that: include: Pretreatment unit, adsorption and desorption unit and RTO; The pretreatment unit is connected to the adsorption and desorption unit; The adsorption-desorption unit is connected to the RTO; The workshop waste gas to be treated is connected to the pretreatment unit, and is transported to the adsorption and desorption unit after being pretreated by the pretreatment unit, and is transported to the RTO for combustion and discharge after being treated by the adsorption and desorption unit.

2. The VOC low emission device according to claim 1, characterized in that: The pretreatment unit comprises: a multi-stage falling film absorption tower and a water washing tower; the multi-stage falling film absorption tower is connected to the water washing tower, and the water washing tower is connected to the adsorption and desorption unit; the workshop waste gas to be treated is connected to the multi-stage falling film absorption tower.

3. The VOC low emission device according to claim 2, characterized in that: The adsorption and desorption unit comprises: a pre-adsorption pretreatment device, a wire mesh air cooler, a main fan and an adsorption and desorption device; the pre-adsorption pretreatment device is connected to the water washing tower; the pre-adsorption pretreatment device is connected to the air inlet end of the main fan through the wire mesh air cooler, and the air outlet end of the main fan is connected to the RTO through the adsorption and desorption device.

4. The VOC low emission device according to claim 3, characterized in that: The adsorption and desorption unit also includes: a first array of tubes, a second array of tubes, a third array of tubes, a drying system and a recovery device; the first array of tubes, the second array of tubes, and the third array of tubes are arranged in the adsorption and desorption device; the first array of tubes, the second array of tubes, and the third array of tubes are connected in series and connected to a condensed water source; one end of the drying system is connected to the first array of tubes, and the other end of the drying system is connected to the second array of tubes; the recovery device is arranged in the adsorption and desorption device, and the recovery device is used to collect and recover condensed substances generated by the first array of tubes, the second array of tubes, and the third array of tubes.

5. The VOC low emission device according to claim 3, characterized in that: The RTO comprises: a thermal oxidation chamber, a heat storage chamber and a combustion chamber; the thermal oxidation chamber is connected to the adsorption and desorption device, and the thermal oxidation chamber is also connected to the combustion chamber through the heat storage chamber.

6. The VOC low emission device according to claim 5, characterized in that: Also includes: Water washing tower and alkali washing tower; The water washing tower is connected to the combustion chamber, and the water washing tower is connected to the alkali washing tower.

7. The VOC low emission device according to claim 6, characterized in that: Also includes: Exhaust fan; the exhaust fan is arranged on the discharge channel of the alkali washing tower.

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