Breathing demisting method, breathing demister and breathing demisting system for atmospheric vessel

Abstract

The invention discloses a breathing demisting method, a breathing demister and a breathing demisting system for a normal-pressure container, and belongs to the technical field of industrial waste gas treatment. According to the method, a hydrophobic membrane filter element type demister is arranged at a breathing opening of a container, so that bidirectional gas-liquid separation is realized: when the container exhausts gas, acid-containing entrainment is intercepted, and clean emission is realized; when the container sucks air, moisture in the air is removed, and equipment corrosion is prevented. The breathing demister comprises a shell and a hydrophobic membrane filter element arranged in the shell, and the shell is provided with an air inlet / outlet, a breathing opening and a liquid outlet. According to the system, a breathing demister is connected with a normal-pressure container to form a complete treatment loop. By utilizing the efficient gas-liquid separation characteristic of the hydrophobic membrane, the two problems of unorganized emission pollution and equipment corrosion in the breathing process of the normal-pressure container are solved at one stroke, and the device has the advantages of being compact in structure, free of maintenance, safe and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental protection treatment process of normal temperature and pressure container, equipment, facility breathing exhaust gas and related equipment, and particularly relates to a sulfuric acid mist removal process and a breathing mist eliminator. BACKGROUND

[0002] The breathing balance of normal pressure containers, equipment and facilities such as storage tanks, intermediate tanks, circulating acid tanks and loading platforms of early domestic sulfuric acid production and storage enterprises generally adopts the direct discharge and direct suction mode of "breathing pipe" to the atmosphere. When the sulfuric acid is poured into the tank, the gas containing a certain amount of acid mist and foam is directly discharged to the atmosphere through the breathing pipe, which is easy to cause unorganized emission pollution to the surrounding environment. Because concentrated sulfuric acid has water absorption, when the sulfuric acid in the tank is exported, the humid air outside is directly sucked into the storage tank through the breathing pipe, and the water in the gas contacts the concentrated sulfuric acid on the liquid surface of the storage tank, locally forming dilute sulfuric acid, which damages the passivation film of the tank body and corrodes the tank wall at the liquid surface of the tank, affecting the service life of the tank body and causing safety risks.

[0003] In recent years, the breathing balance mode of the above-mentioned equipment has been improved in sulfuric acid enterprises. One of the modes is to set a concentrated sulfuric acid liquid seal on the breathing breathing pipe, and when the tank inhales, the humid air passes through the concentrated sulfuric acid liquid seal and is dried, thereby protecting the tank wall and avoiding the risks caused by tank corrosion. However, the diluted concentrated sulfuric acid liquid seal still causes corrosion, so the concentrated sulfuric acid liquid seal needs to be replaced frequently, which increases the operation risk, and when the tank exhales, the acid seal cannot effectively absorb and intercept the acid mist in the "aerosol" state. At this time, due to the bubbling effect of the liquid seal on the air passing through the liquid seal, the liquid seal brings more sulfuric acid mist to the atmosphere, which not only causes more serious unorganized emission pollution to the surrounding atmosphere, but also causes corrosion and damage to the tank shell due to the gravity of the large particle acid mist falling back to the tank surface. Another mode is to connect a pipe to the sulfuric acid production device through the breathing pipe, so that the air containing acid mist and foam when the tank exhales can be directly sent to the device for absorption, thereby avoiding pollution to the atmosphere. However, this mode requires a long pipe with a length of tens to hundreds of meters, which requires a large investment, and the biggest disadvantage is that it cannot be used when the sulfuric acid device is shut down for maintenance, and the valve needs to be closed and switched to the standby port to directly breathe air, so the corrosion and pollution problems have not been completely solved. Another mode is to use nitrogen seal, install a breathing valve on the breathing pipe, and when the tank inhales, nitrogen enters the tank through the breathing valve to maintain nitrogen seal. Because nitrogen has very low water content, the corrosion problem can be basically eliminated, but when the tank exhales, the nitrogen containing acid mist and foam is directly discharged to the atmosphere through the breathing valve, and the unorganized emission pollution problem has not been solved, but the cost of nitrogen use and long-distance transportation pipeline is increased. SUMMARY

[0004] The present application aims to provide an efficient and environmentally friendly acid gas treatment process and equipment technology, solve the pollution caused by unorganized emissions of the surrounding environment due to the breathing balance of the atmospheric pressure vessels, equipment and facilities such as storage tanks, intermediate tanks, circulating acid tanks, loading platforms of sulfuric acid production and storage enterprises, and the safety and personnel operation risks of the above-mentioned equipment and facilities.

[0005] To achieve the above-mentioned purposes, the present application adopts the following technical solutions: The present application provides a breathing demisting method for atmospheric pressure vessels, a hydrophobic membrane filter cartridge demister is arranged at the breathing port of the vessel; when the pressure in the vessel is higher than the outside, the mist-containing gas in the vessel flows through the hydrophobic membrane filter cartridge, the liquid phase mist therein is intercepted, gas-liquid separation is realized, the purified gas is discharged outward, and the intercepted mist flows back to the vessel; when the pressure in the vessel is lower than the outside, the external air flows through the hydrophobic membrane filter cartridge, the moisture therein is intercepted, the dried air enters the vessel, and the intercepted moisture is collected and discharged.

[0006] Preferably, the filtration precision of the hydrophobic membrane filter cartridge is not greater than 0.01 μm.

[0007] Preferably, the liquid phase mist includes mist formed by at least one of sulfuric acid, phosphoric acid, silicic acid, difficult-to-vaporize liquid acid and alkali, or salt solution.

[0008] The present application also provides a breathing demister for realizing the above-mentioned method, which comprises a shell, at least one hydrophobic membrane filter cartridge is arranged in the shell; the shell is also provided with: an inlet / outlet port for connecting with the atmospheric pressure vessel; a breathing port for communicating with the atmosphere; a liquid discharge port for discharging the intercepted liquid.

[0009] Further, the hydrophobic membrane filter cartridge is a folded membrane structure, the skeleton thereof is made of PFA material, the filter membrane thereof is made of PTFE hydrophobic material, the filter cartridge specification is a standard folded filter cartridge with an outer diameter of φ68 mm to φ70 mm, and the length and number of the filter cartridges are determined according to the flow of the liquid in and out of the matched vessel.

[0010] Further, the inner wall surface of the shell is smooth, has no dead angle, and is made of corrosion-resistant material, preferably carbon steel with fluoroplastic sprayed on the inside and outside, and the volume of the shell is designed according to the number of the filter cartridges.

[0011] Further, the diameter of the inlet / outlet port and the breathing port is DN50 to DN500, which is specifically determined according to the flow of the liquid in and out of the matched atmospheric pressure vessel. The diameter of the liquid discharge port is DN15 to DN100, which is specifically determined according to the flow of the liquid in and out of the matched vessel, the mist content of the process gas and the moisture content of the ambient air.

[0012] Further, a pressure detection device is arranged on the upper part of the atmospheric pressure container shell or the pipeline connected with the inlet / outlet port, for monitoring the pressure in the container.

[0013] The present application provides a breathing demister system, comprising: a breathing demister as described above; an atmospheric pressure container, the top breathing port of which is connected with the inlet / outlet port of the breathing demister through a pipeline; wherein the breathing port of the breathing demister is connected with the atmosphere.

[0014] The atmospheric pressure container is one of concentrated sulfuric acid storage tank, intermediate acid tank, circulating acid tank or loading platform (tank car).

[0015] The closed storage tank, intermediate tank, circulating acid tank, loading platform (tank car) and other containers, equipment and facilities of sulfuric acid production and storage enterprises are operated at normal temperature and pressure. During the process of material in and out, pressure is formed inside the equipment, so the top of the equipment or facility is usually designed with a breathing port to breathe outwards and release pressure to maintain normal pressure balance.

[0016] The present application sets a special "breathing demister" at the breathing port of the above-mentioned container, equipment and facility. When the equipment needs to exhale acidic waste gas during the feeding process, the waste gas is removed of mist before being discharged. When the equipment needs to inhale external air during the process of sending material outside the equipment, the moisture in the air is intercepted before being inhaled into the equipment, which can achieve the purpose of environmental protection and equipment protection, and increase the safety guarantee of the operation process. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the front view of the breathing demister of the present application; Figure 2 is the left view of the breathing demister of the present application; Figure 3 is the A-A top view sectional view of the present application; Figure 1 Figure 4 is the filter installation schematic diagram of the present application; Figure 5 is the cooperation schematic diagram of the breathing demister and the sulfuric acid storage tank of the present application, i.e. the process flow diagram. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application, but do not constitute a limitation on the protection scope of the present application.

[0019] ​The process liquid material enters the closed container, under the premise of constant temperature, the material occupies the container space, and the gas in the container is extruded, so that the pressure in the container rises, and vice versa, when the liquid phase material in the container is discharged outward, the negative pressure is formed in the storage tank, which affects the material conveying and equipment safety, so the industrial method of breathing exhaust port of atmospheric pressure container is usually used to maintain the stable pressure in the container.

[0020] The present application focuses on the use of hydrophobic membrane technology. When the gas containing fine liquid mist flows through the membrane filter element, the fine liquid mist is intercepted by the hydrophobic membrane, while the gas flow is not affected, realizing gas-liquid separation.

[0021] The breathing demister designed in the present application is a filter element type, and the key element is a folded membrane filter element. The filter element skeleton is made of PFA material, and the hydrophobic filter membrane is made of PTFE material. The filtration precision of the membrane reaches 0.01 μm. The demister can remove 100% of the mist greater than 1 μm in the gas, and the removal rate of mist less than or equal to 1 μm reaches 99.9%. Through process verification, the total demisting efficiency of the breathing demister reaches 99.99%.

[0022] Table 1 Name, key manufacturing material and quantity of main process equipment and facilities of the present application

[0023] Referring to Figures 1-5 A breathing demister comprises a shell 1, the shape of the shell 1 can be set according to actual needs, and in the embodiment, a cylindrical shell is preferred. A filter element mounting seat 2 is arranged in the shell 1. At least one vertical filter element mounting hole 9 is arranged on the filter element mounting seat 2, and at least one hydrophobic membrane filter element 4 is sleeved on the filter element mounting hole 9. A breathing port 5 is arranged on the side wall of the shell 1, a gas inlet / outlet port 6 connected with the filter element mounting seat 2 is arranged at the central position of the bottom of the shell 1, and a liquid discharge port 7 is further arranged at one side of the bottom of the shell 1.

[0024] In a preferred embodiment of the present application, the hydrophobic membrane filter element 4 is a folded membrane cylindrical structure, comprising a double-layer skeleton pipe made of PFA material and a PTFE folded hydrophobic filter membrane arranged between the inner and outer layers of the skeleton pipe. The inner and outer layer skeleton pipes are densely provided with through holes. A filter element mounting clamping joint with gas inlet / outlet function is arranged at the bottom of each filter element, and is connected with the filter element mounting hole 9. A sealing cover 3 is arranged at the top of the filter element to seal the filter element.

[0025] In a preferred embodiment of the present application, the inner wall surface of the shell is subjected to sand blasting treatment, and the inner wall and the outer wall are both sprayed with a F46 fluoroplastic corrosion-resistant layer.

[0026] In a preferred embodiment of the present application, a top cover 8 is connected to the top of the shell 1 through a flange, and the inner wall and the outer wall of the top cover 8 are both sprayed with a F46 fluoroplastic corrosion-resistant layer.

[0027] In the embodiment of the present application, one or more vertically installed filter element mounting holes 9 are uniformly arranged on the filter element mounting seat 2, and the hydrophobic membrane filter element 4 is arranged on each filter element mounting hole 9. In actual application, the number of filter element mounting holes 9 can be set according to actual needs. For example, the number of filter element mounting holes 9 can be 2, 3, 4, 5, 6, etc. The specific number is determined after the flow area of the required filter element is calculated according to the flow of the process liquid into and out of the atmospheric vessel, and then the number of required filter elements is converted.

[0028] As shown in Figure 5 The present application also provides a breathing demisting system, comprising: a breathing demister 10 as described above; an atmospheric vessel 20, and a breathing interface 25 at the top of the atmospheric vessel 20 is connected to the inlet / outlet port 6 of the breathing demister through a pipeline, wherein the breathing port 5 of the breathing demister is in communication with the atmosphere.

[0029] The top of the atmospheric vessel is also provided with a pressure gauge 21, a breathing standby port 22, and a material inlet 23 and a material outlet 24 at the corresponding positions.

[0030] Specifically, the atmospheric vessel is one of a sulfuric acid tank, an intermediate tank, a circulating tank, or a loading platform in a salt solution.

[0031] Example 1 Taking the breathing demisting system of a 3000m³ concentrated sulfuric acid tank as an example.

[0032] The main purpose of the concentrated sulfuric acid tank is to store 98% concentrated sulfuric acid.

[0033] The concentrated sulfuric acid produced by the sulfuric acid production device is pumped into the tank through the acid inlet at the upper part of the tank after passing the inspection, and the sulfuric acid is discharged from the tank through the acid outlet at the lower part of the tank, and is transported by the acid pump to the nearby acid using device or the loading platform for loading and selling.

[0034] The process flow is described as follows: The process flow diagram of Example 1 is shown in Figure 5.

[0035] Sulfuric acid inlet-gas outlet state: when the concentrated sulfuric acid enters the tank from the upper part of the 3000m³ sulfuric acid tank, the sulfuric acid mist gas in the tank is discharged from the "inlet / outlet port" connected to the lower part of the breathing demister at the top of the tank, and after removing the sulfuric acid mist by the breathing demister, the sulfuric acid mist is discharged from the "breathing port" of the breathing demister, so that the tank maintains a constant pressure, and the removed sulfuric acid mist forms droplets and flows back to the tank through the "inlet / outlet port" of the breathing demister.

[0036] Sulfuric acid out-air in state: when the concentrated sulfuric acid is sent out from the lower part of the 3000m³ sulfuric acid storage tank, the moist air outside the tank enters from the "breathing port" of the breathing demister at the top of the storage tank, enters the tank from the "in / out air port" at the lower part of the breathing demister after removing the moisture by the breathing demister, so that the storage tank maintains constant pressure, and the removed moisture forms liquid drops and falls to the lower part of the breathing demister shell, and is discharged to the water collecting ditch through the "liquid discharge port" of the breathing demister.

[0037] Table 2 Main process technical parameters of the breathing demisting system of the 3000m³ concentrated sulfuric acid storage tank

[0038] Table 3 Design parameters of the breathing demister of the 3000m³ concentrated sulfuric acid storage tank

[0039] Example 2 The breathing demisting system of the 100m³ concentrated sulfuric acid intermediate analysis tank is taken as an example.

[0040] The main purpose of the concentrated sulfuric acid intermediate analysis tank is to temporarily store the 98% concentrated sulfuric acid sent by the production device, and after sampling and analysis, the qualified products are transported by the acid pump to the finished product storage tank for storage, and the unqualified products are transported by the acid pump to the substandard product storage tank for treatment.

[0041] The process flow of Example 2 is basically the same as that of Example 1, and a process flow diagram thereof is shown in Figure 5 .

[0042] Sulfuric acid in-gas out state: when the concentrated sulfuric acid enters the tank from the upper part of the 100m³ concentrated sulfuric acid intermediate analysis tank, the sulfuric acid mist gas in the tank is discharged from the "in / out air port" connected between the top of the intermediate analysis tank and the lower part of the breathing demister, and after removing the sulfuric acid mist by the breathing demister, it is discharged outward from the "breathing port" of the breathing demister, so that the tank maintains constant pressure, and the removed sulfuric acid mist forms liquid drops and flows back to the tank from the "in / out air port" of the breathing demister.

[0043] Sulfuric acid out-air in state: when the concentrated sulfuric acid is output from the lower part of the 100m³ intermediate analysis tank, the moist air outside the tank enters from the "breathing port" of the breathing demister at the top of the intermediate analysis tank, enters the tank from the "in / out air port" connected between the lower part of the breathing demister and the top of the intermediate analysis tank after removing the moisture by the breathing demister, so that the tank maintains constant pressure, and the removed moisture forms liquid drops and falls to the lower part of the breathing demister shell, and is discharged to the water collecting ditch through the "liquid discharge port" of the breathing demister.

[0044] Table 4 Main process technical parameters of the breathing demisting system of the 100m³ concentrated sulfuric acid intermediate analysis tank

[0045] Table 5. Design parameters for the breathing demister of the 100m³ concentrated sulfuric acid intermediate analysis tank.

[0046] After being put into use, the above-mentioned Embodiments 1 and 2 operated normally. After repeated on-site sampling tests, no sulfuric acid mist components were detected in the gas exhaled from the breathing port of the breathing defogger, and no corrosion traces of sulfuric acid mist were found around the breathing port. Based on the overall judgment, the demisting efficiency is >99.99%.

[0047] In summary, this invention not only completely solves the problem of fugitive emissions of acidic gases containing sulfuric acid mist into the atmosphere, but also essentially prevents moisture in the atmosphere from entering the tank, thus solving the corrosion problem of the tank and resolving issues related to environmental pollution, equipment, and operational safety.

[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for breathing demisting of atmospheric pressure vessels, characterized in that, A hydrophobic membrane filter cartridge type mist eliminator is arranged at the breathing port of the container; when the pressure inside the container is higher than the outside, the gas containing mist in the container flows through the hydrophobic membrane filter cartridge, and the liquid phase mist therein is intercepted to achieve gas-liquid separation, and the purified gas is discharged outward, and the intercepted mist flows back to the container; when the pressure inside the container is lower than the outside, the external air flows through the hydrophobic membrane filter cartridge, and the moisture therein is intercepted, and the dried air enters the container, and the intercepted moisture is collected and discharged.

2. The method of claim 1, wherein, The filtering precision of the hydrophobic membrane filter cartridge is not greater than 0.01 μm.

3. The method according to claim 1 or 2, characterized in that, The liquid phase mist includes mist formed by at least one of sulfuric acid, phosphoric acid, silicic acid, inorganic lye or salt solution.

4. A respiratory mist eliminator for use in implementing the method of any one of claims 1 to 3, comprising a housing, characterized in that The housing is provided with at least one hydrophobic membrane filter cartridge; the housing is further provided with: An inlet / outlet port for connecting with the normal pressure container; A breathing port for communicating with the atmosphere; A liquid discharge port for discharging the intercepted liquid.

5. The respiratory mist remover of claim 4, wherein, The hydrophobic membrane filter cartridge is a folded membrane structure, the skeleton of which is made of PFA material, and the filter membrane is made of PTFE hydrophobic material, the filter cartridge is a standard folded filter cartridge with an outer diameter of φ68 mm to φ70 mm, and the length and number of the filter cartridges are determined according to the flow of the liquid into and out of the matched container.

6. The respiratory mist remover of claim 4, wherein, The inner wall surface of the housing is smooth, has no dead angle, and is made of corrosion-resistant material, and the volume of the housing is designed according to the number of filter cartridges.

7. The respiratory mist remover of claim 4, wherein, The diameter of the inlet / outlet port and the breathing port is DN50 to DN500, which is determined according to the flow of the liquid into and out of the matched container, and the diameter of the liquid discharge port is DN15 to DN100, which is determined according to the flow of the liquid into and out of the matched container, the mist content of the process gas and the moisture content of the ambient air.

8. The respiratory mist remover of claim 4, wherein, A pressure detection device is further included, which is arranged on the upper part of the container housing or the pipeline connected with the inlet / outlet port, and is used for monitoring the pressure in the container.

9. A respiratory demisting system characterized by, It comprises: A breathing mist eliminator as claimed in any one of claims 4 to 8; A normal pressure container, the top breathing interface of which is connected with the inlet / outlet port of the breathing mist eliminator through a pipeline; The breathing port of the breathing mist eliminator communicates with the atmosphere.

10. The respiratory mist removal system according to claim 9, wherein, The normal pressure container is one of a storage tank, an intermediate tank, a circulating tank or a loading platform for sulfuric acid, phosphoric acid, silicic acid, inorganic lye or salt solution.

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