A recovery pretreatment device and method for a plurality of VOCs exhaust gas containing heavy components

Abstract

The application belongs to the VOCs treatment field, and discloses a kind of recovery pretreatment device and method of multiple VOCs waste gas containing heavy component, device includes gas collecting main pipe and multiple gas collecting branch, gas collecting branch includes cyclone separator, liquid receiver, switch valve, pressure controller and fan, cyclone separator includes cylindrical section, cone section and guide vane, cone section is arranged at the bottom of cylindrical section, guide vane is arranged in cylindrical section in spiral, inlet is equipped on cylindrical section, exhaust pipe is inserted in the top of cylindrical section, outlet is equipped in the bottom of cone section, inlet is communicated with VOCs waste gas gas collecting branch pipe, exhaust pipe is connected with gas collecting main pipe;Liquid receiver is connected with outlet;Switch valve and pressure controller are arranged on the pipeline of exhaust pipe and gas collecting main pipe;Fan is connected with the gas outlet end of gas collecting main pipe.The application can simultaneously carry out single product recovery pretreatment to multiple VOCs waste gas containing heavy organic matter, and there is no mutual pollution.Not only can long-term operation of downstream VOCs deep purification device be ensured, but also economy is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of VOCs treatment, in particular to a recovery pretreatment device and method for VOCs waste gas containing multiple heavy components. BACKGROUND

[0002] Volatile organic compounds (VOCs) are a series of volatile and flammable toxic organic compounds, including alkanes, alkenes, aromatic hydrocarbons, alcohols, aldehydes, ketones, halogenated hydrocarbons, etc.

[0003] VOCs purification single technology can be divided into recovery and destruction, high concentration VOCs are recovered by condensation, absorption, membrane separation, adsorption, etc., and low concentration waste gas which is difficult to recycle is deep purified by catalytic combustion, thermal incineration, etc. to ensure that the emission meets the standard.

[0004] Although VOCs recovery and deep purification technology is mostly mature, the purification treatment of VOCs waste gas containing heavy components, especially high-viscosity heavy components, such as coal tar waste gas, ethylene tar waste gas, kitchen fume, etc. is still a problem in the industry. Because the heavy components have high viscosity, they are easy to adsorb on the equipment wall, causing blockage (especially porous equipment such as flame arresters and rotating equipment such as fans), affecting mass transfer and heat transfer, and even causing the equipment to fail to operate normally.

[0005] In addition, the current VOCs recovery technology is mostly in the form of mixture, if separate recovery is needed, multiple gas collection systems need to be set up, which has high investment and safety control cost, high operation cost and poor economy. SUMMARY

[0006] The purpose of the present application is to provide a recovery pretreatment device and method for VOCs waste gas containing multiple heavy components, which can simultaneously recover and pretreat VOCs waste gas containing multiple heavy organic compounds, not only ensuring the long-term operation of the downstream VOCs deep purification device, but also having good economy.

[0007] The technical solutions provided by the present application are as follows:

[0008] On the one hand, a recovery pretreatment device for VOCs waste gas containing multiple heavy components is provided, which comprises a gas collection main pipe and multiple gas collection branches, the gas collection branch comprising:

[0009] The cyclone separator comprises a cylindrical section, a conical section and a guide plate, the conical section is arranged at the bottom of the cylindrical section, the guide plate is arranged in the cylindrical section and is arranged in a spiral along the axial direction of the cylindrical section, the cylindrical section is provided with an air inlet, the top of the cylindrical section is provided with an exhaust pipe, the bottom of the conical section is provided with a liquid outlet, the air inlet is connected with a gas collecting branch pipe of VOCs exhaust gas, and the exhaust pipe is connected with a gas collecting main pipe;

[0010] A liquid receiver is connected with the liquid outlet.

[0011] A switch valve is arranged on the connecting pipeline of the exhaust pipe and the gas collecting main pipe.

[0012] A pressure controller is arranged on the connecting pipeline of the exhaust pipe and the gas collecting main pipe and is connected with the switch valve.

[0013] A fan is connected with the gas outlet end of the gas collecting main pipe.

[0014] Further preferably, the number of the cyclone separators in the same gas collecting branch is one or more than two, the air inlets of the cyclone separators are respectively connected with the VOCs exhaust gas collecting branch pipe, and the exhaust pipes of the cyclone separators are respectively connected with the gas collecting main pipe.

[0015] Further preferably, for the gas collecting branch comprising more than two cyclone separators, a differential pressure controller is further arranged, and the differential pressure controller is connected with more than two cyclone separators in the same gas collecting branch.

[0016] Further preferably, the application further comprises:

[0017] A flame arrester is arranged on the connecting pipeline of the exhaust pipe and the gas collecting main pipe, and the air inlet end and the gas outlet end of the fan.

[0018] Further preferably, the application further comprises:

[0019] A VOCs concentration detector is arranged on the gas collecting main pipe; and / or

[0020] A cleaning system is connected with the cyclone separator in each branch.

[0021] Further preferably, the cross section of the air inlet of the cyclone separator is rectangular, the height-width ratio of the rectangular air inlet is 2-1.2, and the cross-sectional area of the air inlet satisfies the VOCs exhaust gas inlet velocity of 10-25 m / s.

[0022] And / or, the cross section of the exhaust pipe is circular, the diameter of the exhaust pipe satisfies that the exhaust rate is 8-15 m / s, and the depth of the exhaust pipe inserted into the cylindrical section is 1.2-1.5 times of the distance from the air inlet to the top of the cylindrical section.

[0023] Further preferably, the diameter of the cylindrical section is 1.3-2 times of the diameter of the exhaust pipe, and the height of the cylindrical section is 2-4 times of the diameter of the cylindrical section.

[0024] Further preferably, the pitch of the guide plate is 1 / 4-1 / 2 of the diameter of the cylindrical section, the width of the guide plate is 1 / 8-1 / 4 of the diameter of the cylindrical section, and the height of the guide plate is 1 / 3-2 / 3 of the height of the cylindrical section.

[0025] Further preferably, the taper angle of the tapered section is 8°-16°, the length of the tapered section is 4-8 times of the diameter of the cylindrical section, and the diameter of the liquid outlet of the tapered section is greater than 30 mm.

[0026] In another aspect, a recovery pretreatment method for VOCs waste gas containing heavy components is also provided, comprising:

[0027] The fan is pressurized, different varieties of VOCs waste gas enter the cyclone separators on the corresponding gas collection branches respectively, and high-speed cyclone motion is made in the cyclone separators, centrifugal force generated by the cyclone is used to separate the VOCs waste gas, the separated waste gas is discharged from the exhaust pipe and enters the gas collection main pipe, and the separated liquid is discharged from the liquid outlet and enters the liquid receiver;

[0028] The pressure controller detects the pressure value on the corresponding gas collection branch;

[0029] When the pressure value is higher than the opening pressure setting value, the corresponding on-off valve is controlled to be opened;

[0030] When the pressure value is lower than the closing pressure setting value, the corresponding on-off valve is controlled to be closed.

[0031] The technical effect of the present application is that:

[0032] (1) A plurality of gas collection branches are arranged on the recovery pretreatment device, which can simultaneously recover and pretreat VOCs waste gas containing heavy organic matter, and the fan is arranged on the gas collection main pipe, so that one fan can be used to simultaneously recover and pretreat multiple varieties of VOCs waste gas, thereby saving investment and operation energy consumption;

[0033] (2) Each gas collection branch uses a cyclone separator to separate the heavy components into gas-liquid-solid, and the flow is guided by the guide plate, so that the fluid collides and cuts, breaks the aerosol, increases the cyclone centrifugal force, effectively removes the free droplets and solid particles, improves the pretreatment efficiency of VOCs waste gas containing heavy components, avoids the blockage of the downstream VOCs deep purification device, and ensures the long-period operation of the downstream VOCs deep purification device. BRIEF DESCRIPTION OF DRAWINGS

[0034] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] Figure 1 is a structural schematic diagram of a multi-heavy component-containing VOCs waste gas recovery pretreatment device of the application;

[0036] Figure 2 is a structural schematic diagram of a cyclone separator of the application;

[0037] Figure 3 is a structural schematic diagram when two cyclone separators are contained in the same gas collection branch of the application.

[0038] Explanation of the reference signs:

[0039] 1, gas collection main pipe; 2, gas collection branch; 21, cyclone separator; 211, cylindrical section; 212, conical section; 213, guide plate; 214, gas inlet; 215, exhaust pipe; 216, liquid outlet; 22, liquid receiver; 23, on-off valve; 24, pressure controller; 3, fan; 4, flame arrester; 5, total controller; 6, VOCs concentration detector; 7, cleaning system; 8, differential pressure controller. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description only represent some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0041] In order to make the drawing simple, only the parts related to the application are shown in each drawing, which does not represent the actual structure of the product. In addition, in order to make the drawing simple and easy to understand, in some drawings, only one of the parts with the same structure or function is shown, or only one of them is marked. In this paper, "one" not only means "only one", but also means "more than one".

[0042] It should be further understood that the term "and / or" as used in the specification and in the claims, if any, means any of the conjunctive or disjunctive list of items that it conjoins, as well as all possible combinations thereof.

[0043] In this document, unless otherwise indicated and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In addition, in the description of the present application, the terms "first", "second" and the like are only used for differentiation and description, and cannot be understood as indicating or implying relative importance.

[0045] The present application provides a specific embodiment of a recovery pretreatment device for various VOCs waste gas containing heavy components, as shown in the figure, which comprises a gas collecting main pipe 1 and a plurality of gas collecting branches 2. The plurality of gas collecting branches 2 are arranged one-to-one with the varieties of VOCs waste gas, that is, one gas collecting branch 2 corresponds to one variety of VOCs waste gas containing heavy organic matter, so as to avoid mutual pollution of organic matters between different varieties. Figure 1

[0046] The waste gas after pretreatment of each gas collecting branch 2 is mixed with the waste gas after pretreatment of other gas collecting branches 2 in the gas collecting main pipe 1. The gas outlet end of the gas collecting main pipe 1 is connected with a fan 3. The waste gas mixed in the gas collecting main pipe 1 is sent to a downstream device for deep treatment through the fan 3 for pressure boosting. The fan 3 is arranged on the gas collecting main pipe 1, which can reduce the number of fan 3 setting stations. Under the condition of ensuring that the collected materials do not pollute each other, one fan 3 can be used to collect multiple VOCs waste gases at the same time, thereby saving investment and operating energy consumption. A flame arrester 4 is arranged on the main pipe before and after the fan 3 to block the flame at the front end and the rear end of the fan 3.

[0047] Each gas collecting branch 2 comprises a cyclone separator 21, a liquid receiver 22, a switch valve 23 and a pressure controller 24. The liquid receiver 22 is connected with the liquid outlet 216 of the cyclone separator 21. The switch valve 23 and the pressure controller 24 are arranged on the connecting pipeline of the exhaust pipe 215 of the cyclone separator 21 and the gas collecting main pipe 1. The switch valve 23 and the pressure controller 24 are both connected with the general controller 5 of the device.

[0048] ​The pressure controller 24 detects the pressure on each gas collection branch 2 and controls the opening and closing of the switch valve 23 according to the detected pressure value, so as to stabilize the pressure on each gas collection branch 2 and control different gas collection branches 2 in the same pressure range, thereby avoiding mutual mixing and backflow among different VOCs exhaust gases and causing pollution of the recovered product. Specifically, when the pressure value on the gas collection branch 2 reaches the opening pressure set value, the general controller 5 controls the corresponding switch valve 23 to open, and the gas collection branch 2 is used for gas collection. When the pressure value on the gas collection branch 2 reaches the closing pressure set value, the general controller 5 controls the corresponding switch valve 23 to close, and the gas collection branch 2 stops collecting gas.

[0049] The gas collection main pipe 1 is also provided with a pressure controller 24, and the pressure stabilization of the gas collection main pipe 1 is controlled by the pressure controller 24 and the general controller 5. The general controller 5 controls the execution of all control circuits on the device. The fan 3 is controlled by frequency conversion. When the pressure on the gas collection main pipe 1 is higher or lower than the preset value, the air volume can be controlled by controlling the operating frequency of the fan 3, which not only ensures stable gas collection and avoids the risk of low pressure vacuum in the system and effective gas collection, but also saves the energy consumption of the fan 3. In addition, the VOCs concentration detector 6 is arranged on the gas collection main pipe 1 to detect the pretreatment effect.

[0050] The exhaust pipe 215 of the cyclone separator 21 of each gas collection branch 2 is respectively provided with a flame arrester 4, which blocks the upstream and downstream flames of the gas collection branch 2, so as to ensure the safety of the gas source of the gas collection branch 2 and the downstream VOCs purification device.

[0051] As shown in Figure 2 The cyclone separator 21 includes a cylindrical section 211, a conical section 212 and a guide plate 213. The conical section 212 is arranged at the bottom of the cylindrical section 211, and the guide plate 213 is arranged in the cylindrical section 211 and is arranged on the inner wall of the cylindrical section 211 in a spiral along the axial direction of the cylindrical section 211. The cylindrical section 211 is provided with an air inlet 214, and the top of the cylindrical section 211 is inserted with an exhaust pipe 215. The bottom of the conical section 212 is provided with a liquid outlet 216. The air inlet 214 is used for communication with the exhaust pipe of the VOCs exhaust gas, and the exhaust pipe 215 is connected with the pipeline of the gas collection main pipe 1.

[0052] In the gas collecting branch 2, the VOCs waste gas containing heavy components enters the cyclone separator 21 and makes high-efficiency cyclone movement in the cyclone separator 21, and the gas-liquid (solid) separation is completed by using the centrifugal force generated by the cyclone. Specifically, the VOCs waste gas tangentially enters the cylindrical section 211 at a certain speed with liquid entrained, under the guide of the guide plate 213, the VOCs waste gas rotates at high speed and forms an inner and outer double-layer fast rotating flow, the outer layer is downward cyclone below the guide plate 213, and the inner layer is upward cyclone, and the VOCs waste gas continuously entering from the gas inlet 214 provides the cyclone power when the outer layer rotates downward, in the cyclone process, the liquid entrained in the VOCs waste gas is thrown to the pipe wall, that is, the liquid with a larger density is thrown to the pipe wall under the action of the centrifugal force, and flows downward along the pipe wall under the action of the gravity and the downward cyclone gas phase thrust, and flows out from the liquid outlet 216 at the bottom of the conical section 212, and is received by the liquid receiver 22, the inner layer is the cyclone gas, and the gas with a lighter density is in the center of the vortex and rotates upward and is discharged from the top exhaust pipe 215, so as to realize the liquid (solid) pretreatment of the VOCs waste gas. The free liquid removal efficiency of the cyclone separator 21 in the embodiment is greater than 90%.

[0053] In the embodiment, the cross section of the gas inlet 214 of the cyclone separator 21 is rectangular, and the height-width ratio of the rectangular gas inlet 214 is 2-1.2, when the height-width ratio of the gas inlet 214 is higher than this range, the VOCs waste gas flow rate is too large to cause too large cyclone separation pressure drop, and the too large separation pressure drop contributes little to the separation efficiency, and when the height-width ratio of the rectangular gas inlet 214 is lower than this range, the cyclone separation pressure drop is small, which reduces the separation efficiency, and the height-width ratio of the rectangular gas inlet 214 is 2-1.2, which can meet the VOCs waste gas inlet rate of 10-25 m / s, so that the VOCs waste gas entering the cyclone separator 21 has a suitable initial speed to provide a suitable centrifugal force.

[0054] The cross section of the exhaust pipe 215 of the cyclone separator 21 is circular, the diameter of the exhaust pipe 215 meets the exhaust rate of 8-15 m / s, and the depth of the exhaust pipe 215 inserted into the cylindrical section 211 is 1.2-1.5 times the height of the gas inlet 214 from the top of the cylindrical section 211, that is, one end of the exhaust pipe 215 inserted into the cylindrical section 211 is located below the gas inlet 214, so that the VOCs waste gas entering from the gas inlet 214 will not be directly discharged from the exhaust pipe 215, but will form downward cyclone in the cyclone separator 21. When the depth of the exhaust pipe 215 inserted into the cylindrical section 211 is too deep, it contributes little to the separation efficiency.

[0055] The diameter of the cylindrical segment 211 is 1.3-2 times the diameter of the exhaust pipe 215, and the diameter of the exhaust pipe 215 is set according to the intake amount of the VOCs exhaust gas. In the case of a certain intake amount, if the diameter of the cylindrical segment 211 is too large, the flow rate of the VOCs exhaust gas will be reduced, the rotational flow rate will be reduced, the centrifugal force will be small, and the separation efficiency will be poor. If the diameter of the cylindrical segment 211 is too small, the pressure drop will be too large. The height of the cylindrical segment 211 is 2-4 times the diameter of the cylindrical segment 211. If the height of the cylindrical segment 211 is too short, the separation efficiency will be poor, and if the height of the cylindrical segment 211 is too long, it will be uneconomical.

[0056] The pitch of the guide plate 213 is 1 / 4-1 / 2 of the diameter of the cylindrical segment 211, the width of the guide plate 213 is 1 / 8-1 / 4 of the diameter of the cylindrical segment 211, and the height of the guide plate 213 is 1 / 3-2 / 3 of the height of the cylindrical segment 211. The guide plate 213 is spirally arranged along the inner wall of the cylindrical segment 211. The guide plate 213 prevents the exhaust gas from flowing upwards when disturbed, and under the guide action of the guide plate 213, the VOCs exhaust gas entering the rotational flow separator 21 rotates downwards, and an inner and outer double-layer fast rotating flow is formed below the guide plate 213.

[0057] The taper angle of the tapered segment 212 is 8°-16°, and the length of the tapered segment 212 is 4-8 times the diameter of the cylindrical segment 211. The liquid outlet 216 of the tapered segment 212 has a diameter greater than 30 mm to prevent blockage. The length of the tapered segment 212 determines the residence time of the rotational flow. If the length of the tapered segment 212 is too short, the residence time of the rotational flow is short, and the separation efficiency is low. If the length of the tapered segment 212 is too long, the speed of the rotational flow gradually decreases, which does not contribute much to the rotational flow separation efficiency, and is not economical.

[0058] Preferably, as shown in Figure 1 The recovery pretreatment device further comprises a cleaning system 7 connected to each rotational flow separator 21, and the cleaning system 7 can use a cleaning agent to clean the inner surface of the rotational flow separator 21. The cleaning agent of the present application is a 5% NaOH solution. After alkaline washing with the NaOH solution, the inner surface of the rotational flow separator 21 is washed with clean water. The cleaning agent does not produce VOCs pollution and does not pollute the collected organic matter.

[0059] For VOCs exhaust gas containing high-viscosity heavy components, the existing technology generally uses diesel absorption process. Although this process can successfully remove high-viscosity heavy components in VOCs exhaust gas, it has two problems. First, the diesel absorption is arranged after the fan, which cannot solve the problem of easy blockage of the delivery fan and the fire resistance before and after the fan. Second, since the high-viscosity heavy components are difficult to recover, the recovery rate of diesel after absorbing high-viscosity heavy components such as tar is low, the energy consumption is high, and the economy is poor.

[0060] As shown in Figure 3As shown, the multiple cyclone separators 21 are used for pretreatment in the present application. Since high-viscosity materials will adhere to the inner wall of the cyclone separator 21, two or more cyclone separators 21 can be arranged in the gas collection branch 2 for treating high-viscosity VOCs waste gas. The gas inlets 214 of the two or more cyclone separators 21 are respectively connected with the gas collection branch of the VOCs waste gas, and the exhaust pipes 215 of the two or more cyclone separators 21 are respectively connected with the pipeline of the gas collection main pipe 1. That is, when a certain gas collection branch 2 needs to treat high-viscosity VOCs waste gas, two or more cyclone separators 21 need to be arranged in the gas collection branch 2, and the multiple cyclone separators 21 are connected in parallel to facilitate switching. The multiple cyclone separators 21 are used for rotation and cleaning in turn, which can remove more than 90% of the liquid (or solid) high-viscosity heavy components, effectively prolong the operation cycle of the downstream VOCs purification device, and successfully solve the purification treatment problem of high-viscosity VOCs waste gas.

[0061] Preferably, the multiple cyclone separators 21 are respectively connected with the differential pressure controller 8. When the differential pressure of the running cyclone separator 21 exceeds the set value, the total controller 5 will automatically control the running cyclone separator 21 to be offline, switch another cyclone separator 21 to be online, and start the cleaning system 7 to clean the switched-off cyclone separator 21. For example, when two cyclone separators 21 are arranged, after the total controller 5 detects that the cyclone differential pressure of the online running cyclone separator A is increased to the set value due to excessive adhesion of heavy components, the cyclone separator B is switched to be online, the cyclone separator A is switched to be offline, and then the cleaning system 7 is started to clean the cyclone separator A.

[0062] The recycling pretreatment device of the present application is composed of multiple gas collection branches 2. Each gas collection branch 2 corresponds to the collection and pretreatment of a VOCs waste gas source containing heavy organic matter. Each gas collection branch 2 contains at least one cyclone separator 21. The gas collection branch 2 for treating VOCs waste gas containing high-viscosity heavy components contains at least two cyclone separators 21.

[0063] The processing flow of the recycling pretreatment device of the VOCs waste gas containing heavy components in the present embodiment is as follows:

[0064] The fan 3 is pressurized. Different types of VOCs waste gas enter the corresponding cyclone separators 21 in the respective gas collection branches 2 and perform high-speed cyclone motion in the cyclone separators 21. The centrifugal force generated by the cyclone is used for gas-liquid separation of the VOCs waste gas. The separated waste gas is discharged from the exhaust pipe 215 and enters the gas collection main pipe 1, and the separated liquid is discharged from the liquid outlet 216 and enters the liquid receiver 22.

[0065] The pressure controller 24 detects the pressure value of the corresponding gas collection branch 2.

[0066] When the pressure value is higher than the opening pressure setting value, the corresponding switch valve 23 is opened;

[0067] When the pressure value is lower than the closing pressure setting value, the corresponding switch valve 23 is closed.

[0068] The VOCs waste gas 1, waste gas 2, waste gas 3 containing heavy components from the upstream enters the corresponding gas collection branch 2 respectively, in the gas collection branch 2, the VOCs waste gas first enters the cyclone separator 21, and does high-speed cyclone motion in the cyclone separator 21, and completes gas-liquid (solid) separation by using the centrifugal force generated by the cyclone. The waste gas entrains liquid to enter the cylindrical section 211 of the cyclone separator 21 tangentially at a certain speed, under the action of the guide plate 213, high-speed rotation is formed, double-layer fast rotating flow is formed, the outer layer is downward rotating flow, and the inner layer is upward rotating flow. The liquid with larger density is thrown to the pipe wall under the action of the centrifugal force, and flows downward along the pipe wall under the action of the gravity and the downward rotating flow gas phase thrust, and flows out at the bottom of the conical section 213, and is received by the liquid receiver 22; the gas with lighter density is upward rotating flow in the center of the vortex, and is discharged from the top exhaust pipe 215, so that the liquid (solid) pretreatment of the VOCs waste gas is realized. After the liquid (solid) pretreatment, the VOCs waste gas is mixed with the pretreated waste gas of other branches in the gas collection main pipe 1, and is sent to the downstream deep treatment device for deep treatment by the fan 3.

[0069] The pressure stability of the branch gas collection is controlled by the total controller 5, when the pressure controller 24 detects that the pressure value on the corresponding gas collection branch 2 reaches the high setting value, the corresponding switch valve 23 is opened, and the gas collection branch 2 is collected; when the pressure value reaches the low setting value, the corresponding switch valve 23 is closed, and the gas collection branch 2 is stopped.

[0070] The application will be further described below by combining with specific examples.

[0071] Comparative example 1

[0072] The ethylene tar loading VOCs waste gas is purified, after the waste gas is separated by the conventional gas-liquid separation tank, the waste gas is purified by the subsequent VOCs treatment device, the device runs for 3 months, the compressor, the heat exchanger, the flame arrester and the like are completely blocked, and cannot normally run. The device is shut down for maintenance, and a large amount of solidified tar is cleaned out.

[0073] Comparative example 2

[0074] Purification of three VOCs exhaust gas: ① coal tar storage tank exhaust gas, ② oxalic acid dimethyl ester VOCs exhaust gas (100℃), ③ benzene storage tank VOCs exhaust gas. Benzene and oxalic acid dimethyl ester have high added value and need to be separately recycled and utilized, and the coal tar storage tank exhaust gas belongs to high-viscosity heavy components and needs to be separately removed by absorption. In order to separately recycle the heavy components in the VOCs exhaust gas, three gas collection systems and three different pretreatment devices are used for the three kinds of component exhaust gas.

[0075] In order to avoid the pollution of the tar in the coal tar exhaust gas to the subsequent purification device, a separate gas collection and pretreatment system is used for the coal tar storage tank exhaust gas. First, the fan is used for pressurization, and then the diesel absorption unit is used for sending. The heavy diesel oil is used for dissolving and removing the tar components in the exhaust gas, and then the subsequent VOCs purification unit is used for treatment. In order to ensure the absorption efficiency, 10 m 3 / hr diesel oil (supplement fresh diesel oil and extract absorbed diesel oil) is replaced every hour. This 10 m 3 / hr needs to be sent back to the upstream device for reprocessing, which consumes a large amount of energy.

[0076] The benzene exhaust gas uses a separate condensation recovery pretreatment system, that is, the fan is used for pressurization, and then the benzene is recovered by shallow cooling to about 5℃ (higher than the freezing point of benzene), and then the deep treatment device is used for deep treatment. The oxalic acid dimethyl ester VOCs exhaust gas is pressurized by a separate gas collection fan, and then the exhaust gas is cooled to about 65℃ (higher than the freezing point of oxalic acid dimethyl ester) by hot water to recover the oxalic acid dimethyl ester, and then the downstream deep treatment device is used.

[0077] Among the three pretreatment devices, the removal rate of the heavy components of the coal tar VOCs exhaust gas is greater than 90%, but the energy consumption of 10 m 3 / hr diesel oil reprocessing is large, and since the fan is arranged before the diesel absorption, the fan and the flame arrester before the fan in this gas branch are blocked after 3.5 months of operation; although the other two routes are not blocked, the recovery rate of benzene is only 70%, and the recovery rate of oxalic acid dimethyl ester is only 65%. The low recovery rate causes large load of the downstream device.

[0078] Example 1

[0079] The same as comparative example 1, the VOCs exhaust gas purification of the ethylene tar loading is carried out, and different from comparative example 1, the VOCs exhaust gas purification process of the high-viscosity heavy component pollution of the application is used, that is, the ordinary gas-liquid separation tank before the fan is replaced by two AB high-efficiency cyclone separators, the pressure drop of the cyclone separator is monitored, and the AB cyclone separators are controlled to be on line for pretreatment and removal of tar in turn.

[0080] The structure of the cyclone separator used in this embodiment is as follows: the rectangular inlet has a height-width ratio of 1.8, and the cross-sectional area meets the flow rate of 20 m / s; the exhaust pipe has an exhaust flow rate of 10 m / s, the insertion depth of the exhaust pipe in the cylindrical section is 1.2 times the height of the inlet, the diameter D of the cylindrical section is 1.5 times the diameter of the exhaust pipe, the length of the cylindrical section is 3 times its diameter, 3 layers of guide plates are arranged in the cylindrical section, the spacing between the guide plates is 22 mm, and the pitch is 1 / 4 of the diameter of the cylinder. The width of the guide plate is 1 / 5 of the diameter of the cylindrical section, and the guide plate is arranged in the range of 1 / 3 of the height of the cylinder.

[0081] The cleaning agent used in the cleaning operation is a NaOH solution with a concentration of 5% at 50°C, and the alkali cleaning is followed by water washing. In actual operation, the removal rate of tar is 91%, the pressure drop of the cyclone separator is 1.2 KPa, and the A / B cyclone separator is switched and cleaned every 3 months. The subsequent advanced treatment device has been continuously running and has not been blocked.

[0082] Example 2

[0083] Except that the cleaning liquid is different from that of Example 1, the others are the same as those of Example 1. The cleaning liquid of this embodiment is a NaOH solution with a concentration of 5% at 60°C. In actual operation, the recovery rate of tar is 90%, the pressure drop of the cyclone separator is 1.1 KPa, and the A / B cyclone separator is switched and cleaned every 3 months. The subsequent advanced treatment device has been continuously running and has not been blocked.

[0084] Example 3

[0085] Except that the insertion depth of the exhaust pipe in the cylindrical section is different from that of Example 1, the others are the same as those of Example 1. The insertion depth of the exhaust pipe in the cylindrical section of this embodiment is 1.4 times the height of the inlet. In actual operation, the recovery rate of tar is 92%, the pressure drop of the cyclone separator is 1.4 KPa, and the A / B cyclone separator is switched and cleaned every 3 months. The subsequent advanced treatment device has been continuously running and has not been blocked.

[0086] Example 4

[0087] Except that the height-width ratio of the inlet of the cyclone separator is different from that of Example 1, the others are the same as those of Example 1. The height-width ratio of the inlet of the cyclone separator of this embodiment is 1.2. In actual operation, the recovery rate of tar is 90%, the pressure drop of the cyclone separator is 1.1 KPa, and the A / B cyclone separator is switched and cleaned every 3 months. The subsequent advanced treatment device has been continuously running and has not been blocked.

[0088] Example 5

[0089] The raw material VOCs waste gas is the same as that of the comparative example 2, which is three different heavy component VOCs waste gases: one is coal tar storage tank waste gas, one is oxalic acid dimethyl ester VOCs waste gas (100℃), and one is benzene storage tank VOCs waste gas. Different from the comparative example 2, the device of the present application is used, that is, one set of gas collection system + three sets of cyclone heavy component recovery pretreatment gas collection branch, and the fan is arranged after the three gas collection branches. The benzene-containing waste gas is controlled at about 5℃ for cyclone fractionation, the oxalic acid dimethyl ester is controlled at 45℃ for cyclone gas, liquid and solid separation. For the high-viscosity coal tar storage tank waste gas, two AB cyclone separators are used for separation at room temperature, and the AB cyclone separators are alternately put into operation and cleaned. The structure of the cyclone separator and the cleaning procedure of the cyclone separator for treating the tar are the same as those of the example 1.

[0090] In actual operation, the recovery rate of the tar is 90%, the recovery rate of benzene is 80%, the recovery rate of oxalic acid dimethyl ester is 90%, the pressure drop of the cyclone separator is about 1.2KPa, the A\B cyclone separators are switched and cleaned every 3 months. The downstream deep treatment is continuously and stably operated. Compared with the comparative example 2, the present example reduces 4 fans, reduces the power consumption by 2 / 3, does not consume diesel oil, and has high recovery rates of benzene and oxalic acid dimethyl ester.

[0091] Example 6

[0092] Except that the cyclone separation of the benzene-containing waste gas is controlled at 2℃, the other conditions are the same as those of the example 5. In actual operation effect, the recovery of benzene is 90%, and the other operation parameters are the same as those of the example 5.

[0093] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A recovery pretreatment device for a plurality of VOCs exhaust gas containing heavy components, characterized by, The device comprises a gas collecting main pipe and a plurality of gas collecting branch pipes, wherein the gas collecting branch pipes comprise: A cyclone separator, comprising a cylindrical section, a conical section and a guide plate, the conical section is arranged at the bottom of the cylindrical section, the guide plate is arranged in the cylindrical section and is arranged in a spiral along the axial direction of the cylindrical section, the cylindrical section is provided with an air inlet, the top of the cylindrical section is inserted with an exhaust pipe, the bottom of the conical section is provided with a liquid outlet, the air inlet is used for communicating with the VOCs exhaust gas collecting branch pipe, and the exhaust pipe is connected with the gas collecting main pipe; A liquid receiver connected with the liquid outlet; A switch valve arranged on the connecting pipeline between the exhaust pipe and the gas collecting main pipe; A pressure controller arranged on the connecting pipeline between the exhaust pipe and the gas collecting main pipe and connected with the switch valve; A fan connected with the gas outlet end of the gas collecting main pipe; The cross section of the air inlet of the cyclone separator is rectangular, the height-width ratio of the rectangular air inlet is 2-1.2, and the cross-sectional area of the air inlet satisfies that the VOCs exhaust gas inlet velocity is 10-25 m / s; And / or, the cross section of the exhaust pipe is circular, the diameter of the exhaust pipe satisfies that the exhaust velocity is 8-15 m / s, and the depth of the exhaust pipe inserted into the cylindrical section is 1.2-1.5 times the height of the air inlet from the top of the cylindrical section; The diameter of the cylindrical section is 1.3-2 times the diameter of the exhaust pipe, and the height of the cylindrical section is 2-4 times the diameter of the cylindrical section; The pitch of the guide plate is 1 / 4-1 / 2 of the diameter of the cylindrical section, the width of the guide plate is 1 / 8-1 / 4 of the diameter of the cylindrical section, and the height of the guide plate is 1 / 3-2 / 3 of the height of the cylindrical section.

2. The VOCs exhaust gas recovery pretreatment device according to claim 1, wherein the number of the cyclone separators in the same gas collecting branch pipe is one or more than two, and the air inlets of the cyclone separators are respectively used for communicating with the VOCs exhaust gas collecting branch pipe.

3. The VOCs exhaust gas recovery pretreatment device according to claim 2, wherein for the gas collecting branch pipe comprising more than two cyclones, a differential pressure controller is further arranged and connected with the more than two cyclone separators in the same gas collecting branch pipe. Further comprising: A flame arrester arranged on the connecting pipeline between the exhaust pipe and the gas collecting main pipe, and the air inlet end and the gas outlet end of the fan.

4. The apparatus for recovering and pretreating a plurality of VOCs exhaust gas containing heavy components according to claim 1, characterized in that, Further comprising: A VOCs concentration detector arranged on the gas collecting main pipe.

5. The apparatus for recovering and pretreating a plurality of VOCs exhaust gas containing heavy components according to claim 1, characterized in that, And / or; A cleaning system connected with each cyclone separator.

6. The VOCs exhaust gas recovery pretreatment device according to claim 1, wherein the cone angle of the conical section is 8-16°, the length of the conical section is 4-8 times the diameter of the cylindrical section, and the diameter of the liquid outlet of the conical section is greater than 30 mm. ​ ​ ​ 7. A recovery pretreatment method of a plurality of VOCs exhaust gas containing heavy components, characterized by, The method is applied to the recovery pretreatment device of the VOCs waste gas containing heavy components according to any one of claims 1-6, and the method comprises: Fan pressurization, different varieties of VOCs waste gas respectively enter the cyclone separators on the corresponding gas collection branch, and high-speed cyclone motion is made in the cyclone separators, centrifugal force generated by cyclone is used for gas-liquid separation of the VOCs waste gas, the separated waste gas is discharged from the exhaust pipe and enters the gas collection main pipe, and the separated liquid is discharged from the liquid outlet and enters the liquid receiver; The pressure controller detects the pressure value on the corresponding gas collection branch; When the pressure value is higher than the opening pressure setting value, the corresponding on-off valve is controlled to be opened; When the pressure value is lower than the closing pressure setting value, the corresponding on-off valve is controlled to be closed.

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