Acidolysis tail gas treatment device

Abstract

The utility model relates to the technical field of acidolysis tail gas treatment, in particular to an acidolysis tail gas treatment device which comprises a venturi scrubber, a gas-liquid separator, a filler scrubbing tower, an induced draft fan and an exhaust funnel, and a body consists of an anti-blocking nozzle, a contraction section, a throat pipe and a diffusion section; the gas-liquid separator is composed of a body, a demister, a liquid level detection control instrument and the like. The filler washing tower is composed of a body, filler, a spraying distributor, a demister, a washing tower circulating pump, a washing tower drain pipe, a liquid level detection control instrument and the like. Process water provided by the utility model is only supplemented to the sulfuric acid mist filler washing tower, the washing tower discharges or overflows to the venturi scrubber, and the venturi scrubber is not supplemented with the process water and is only suitable for circulating liquid of the sulfuric acid mist filler washing tower, so that the sulfuric acid concentration and the dust concentration of the circulating liquid of the sulfuric acid mist filler washing tower can be reduced to the maximum extent; the highest absorption efficiency is guaranteed, the possibility of scaling and blocking is avoided, and meanwhile the overall water discharge amount is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of acidolysis tail gas treatment, in particular to an acidolysis tail gas treatment device. Background Art

[0002] In the production processes of new energy lithium ore, titanium dioxide, rare earth mineral powder and other industries, sulfuric acid is used to acid-lyze the ground mineral powder and roast it at a certain temperature for a period of time. During the acid-lysis and material dissolution process, a large amount of exhaust gas containing high-concentration particulate matter, sulfuric acid mist, carbon dioxide and water vapor is generated, which seriously pollutes the production environment and the atmospheric environment.

[0003] After searching, the patent application number is (201110202460.9), which discloses "a rare earth ore powder and concentrated sulfuric acid roasting process tail gas treatment process". This process introduces the 300°C process tail gas into the dust collector for mechanical dust removal; then introduces it into the cooler for cooling, and a large amount of sulfuric acid mist and water vapor in the flue gas are condensed and recovered as acid liquid for reuse; the cooled flue gas enters the acid mist collector to capture the acid mist and water mist in the flue gas for recycling; the treated flue gas is pressurized by the fan and enters the first absorber, and the remaining sulfuric acid mist, hydrofluoric acid and fluorosilicic acid in the flue gas are removed by washing with dilute acid or process water; then enters the second absorber, and the flue gas is washed by the alkaline washing tower to remove the remaining sulfuric acid mist, hydrofluoric acid and SO2 gas in the flue gas, and then discharged after demisting. The present invention can not only save a lot of water for flue gas cooling, reduce the amount of wastewater generated, and lower the cost of wastewater treatment, but also recover by-product fluoric acid generated by solid minerals, sulfuric acid, hydrofluoric acid and other substances in the tail gas as a raw material for fluorine recovery and utilization.

[0004] A search revealed patent application number (201210235007.2), which discloses a "Method for Treating Titanium Dioxide Acid Hydrolysis Exhaust Gas." The high-temperature acid hydrolysis exhaust gas generated by the sulfuric acid-based titanium dioxide process is scrubbed, absorbed, and cooled in a scrubber. The cooled, reduced-volume exhaust gas is then passed through a venturi, achieving standard exhaust gas treatment and clean production. The present invention maintains the pH value of the liquid in the circulating pool at ≥4.5, ensuring that the exhaust gas temperature is reduced to below 90°C during the main reaction. The significantly reduced-volume exhaust gas is then passed through a venturi, which utilizes waste alkali generated by the sulfuric acid-based titanium dioxide process, achieving standard exhaust gas treatment and clean production. In the scrubber, the large amount of circulating liquid used for scrubbing absorbs most of the sulfuric acid mist and sulfur dioxide gas in the exhaust gas, resulting in minimal consumption of dilute alkali in the subsequent venturi scrubber.

[0005] The main principles of existing treatment technologies include: cooling condensation, spray washing, acid-base neutralization, etc. Due to dust blockage, difficulty in absorbing acid mist, and large amounts of wastewater generation, the equipment failure rate is high, the treatment effect is poor, and it cannot stably meet the standards.

[0006] However, the above-mentioned device has the following problems: 1. Sulfuric acid mist behaves like an aerosol. Removing it through condensation is not feasible industrially except in laboratories. Ultra-low emission modifications such as boiler flue gas condensation have struggled to achieve their intended purpose. Existing patents do not explain the contact mechanism between sulfuric acid mist and the absorption liquid, relying solely on acid-base neutralization theory. According to published papers, the typical removal efficiency is only 20% to 30%.

[0007] 2. The tail gas contains a large amount of dust and water vapor, which can easily cause equipment pipeline blockage during the treatment process. The existing patented technology does not detect this, resulting in a high equipment failure rate, short operating cycle, and even complete loss of treatment function;

[0008] 3. The application of existing patented technologies produces a large amount of high-salt slurry wastewater, which is difficult to treat. At the same time, due to the introduction of Na+ ions, the by-products cannot be recycled into the production system, otherwise it will pollute product quality and cause resource waste. To this end, we have proposed an acid hydrolysis tail gas treatment device to solve the above problems. Utility Model Content

[0009] The purpose of the utility model is to provide an acid hydrolysis tail gas treatment device to solve the problems raised in the above background technology, such as high wastewater generation, high equipment failure rate, poor treatment effect, and failure to meet standards stably.

[0010] To achieve the above-mentioned object, the present invention provides the following technical solution: an acidolysis tail gas treatment device, comprising a venturi scrubber, a gas-liquid separator, a packed scrubber, an induced draft fan, and an exhaust pipe, wherein the rear end of the venturi scrubber is provided with a gas-liquid separator, the rear end of the gas-liquid separator is provided with a packed scrubber, the rear end of the packed scrubber is provided with an induced draft fan, and the rear end of the induced draft fan is provided with an exhaust pipe;

[0011] The venturi scrubber comprises a scrubber body and a venturi circulation pump, wherein the body is composed of an anti-clogging nozzle, a contraction section, a throat pipe, and a diffusion section;

[0012] The gas-liquid separator is composed of components including a gas-liquid separator body, a demister, and a liquid level detection and control instrument. The demister is designed to be a baffle type that prevents scaling and clogging. The gas-liquid separator in the Venturi scrubber uses a centrifugal air intake method to improve the separation effect by using a centrifuge.

[0013] The packed scrubber is composed of components including a packed scrubber body, packing, a spray distributor, a demister, a scrubber circulation pump, a scrubber drain pipe and a liquid level detection and control instrument; the packing, the spray distributor and the demister are all designed to prevent scaling and clogging.

[0014] Preferably, the packed washing tower uses process water as the absorption liquid, and the washing tower discharge pipe is connected to the Venturi washing unit, and the Venturi washing unit does not use process water.

[0015] Preferably, the gas-liquid separator adopts a gravity type or a cyclone type, and a demister is provided before the outlet of the gas-liquid separator.

[0016] Further preferably, the demister adopts a high-efficiency baffle type rather than a wire mesh type to ensure long-term reliable operation.

[0017] Preferably, the anti-clogging nozzle includes a stainless steel nozzle, a storage tank and a semicircular protrusion. The end of the anti-clogging nozzle is installed with a stainless steel nozzle, the inner wall of the stainless steel nozzle is provided with a storage tank, and several groups of semicircular protrusions are equidistantly connected in the storage tank.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This utility model provides an acidolysis tail gas treatment device. It proposes that process water for the entire treatment system is only added to the sulfuric acid mist packing scrubber. The scrubber discharges or overflows into a venturi scrubber. The venturi scrubber does not receive process water, but only uses the circulating fluid from the sulfuric acid mist packing scrubber. This minimizes the sulfuric acid and dust concentrations in the circulating fluid of the sulfuric acid mist packing scrubber, ensuring maximum absorption efficiency and avoiding the possibility of scaling and clogging, while also reducing the overall amount of water discharged. The sulfuric acid and solids concentrations in the scrubbing fluid of the packing scrubber are preferably controlled to less than 1%, and the sulfuric acid and solids concentrations in the scrubbing fluid of the venturi scrubber are preferably controlled to less than 5%.

[0020] The utility model proposes a treatment system that is only suitable for process water absorption and does not use alkali solution, thereby avoiding the generation of high-salt wastewater and the pollution of product quality by the introduced Na+ ions, so that the recovered by-products (dust, acid solution) can be recycled to the production system, thereby realizing resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of the device of the utility model;

[0023] Figure 2 It is a cross-sectional schematic diagram of the stainless steel nozzle of the utility model.

[0024] In the figure: 1. Venturi scrubber; 101. Stainless steel nozzle; 102. Storage tank; 103. Semicircular protrusion; 11. Venturi circulation pump; 2. Gas-liquid separator; 3. Packed scrubber; 31. Scrubber circulation pump; 32. Scrubber drain pipe; 4. Induced draft fan; 5. Exhaust stack. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] See also Figure 1-2 The utility model provides an embodiment of an acidolysis tail gas treatment device, comprising a venturi scrubber 1, a gas-liquid separator 2, a packed scrubber 3, an induced draft fan 4 and an exhaust pipe 5. The rear end of the venturi scrubber 1 is provided with a gas-liquid separator 2, the rear end of the gas-liquid separator 2 is provided with a packed scrubber 3, the rear end of the packed scrubber 3 is provided with an induced draft fan 4, and the rear end of the induced draft fan 4 is provided with an exhaust pipe 5;

[0027] The venturi scrubber 1 comprises a scrubber body and a venturi circulation pump 11. The body is composed of an anti-clogging nozzle, a contraction section, a throat pipe, and a diffusion section.

[0028] The gas-liquid separator 2 consists of a main body, a demister, and a liquid level detection and control instrument. The demister is designed to be a baffle type that prevents scaling and clogging. The gas-liquid separator 2 in the Venturi scrubber 1 preferably uses a centrifugal air intake method to improve the separation effect by using a centrifuge.

[0029] The packed scrubber 3 consists of a main body, packing, a spray distributor, a demister, a scrubber circulation pump 31, a scrubber drain pipe 32, and a liquid level detection and control instrument. The packing, spray distributor, and demister are all designed to prevent scaling and clogging.

[0030] This device can achieve efficient removal of dust and acid mist and realize resource recycling through the acid hydrolysis tail gas treatment device.

[0031] Furthermore, the packed scrubber 3 uses process water as the absorption liquid, and the scrubber drain pipe 32 is connected to the venturi scrubber unit, which does not use process water. Figure 1 As shown, this structure is used to avoid the generation of high-salt wastewater by not using alkali solution, and also avoids the pollution of product quality by the introduced Na+ ions.

[0032] Furthermore, the gas-liquid separator 2 adopts gravity type or cyclone type, and a demister is provided before the outlet of the gas-liquid separator 2. The demister adopts high-efficiency baffle type instead of wire mesh type to ensure long-term reliable operation. Figure 1 As shown, this structure is used to avoid blockage of equipment pipelines through the installation of demisters, which leads to high equipment failure rate, short operation cycle, or even complete loss of treatment function.

[0033] Furthermore, the anti-clogging nozzle includes a stainless steel nozzle 101, a storage tank 102 and a semicircular protrusion 103. The end of the anti-clogging nozzle is equipped with the stainless steel nozzle 101. The inner wall of the stainless steel nozzle 101 is provided with a storage tank 102. Several groups of semicircular protrusions 103 are equidistantly connected in the storage tank 102. Figure 2 As shown, the structure is used to use the storage tank 102 as a storage area for impurity particles. When the impurity particles enter the nozzle, they will move toward the center hole under the action of the fluid and their own inertia. The impurity particles must first contact the semicircular protrusion 103 so that they adhere to the surface of the semicircular protrusion 103 to avoid blockage.

[0034] Working principle:

[0035] Step S1: Use a Venturi scrubber 1 to transfer dust into a washing liquid through high-speed collision. The washing liquid is recycled and discharged into the production system's slurry tank and other equipment for recycling after the solid content or acid concentration reaches a certain level. The washing liquid is replenished with drainage from the acid mist washing tower rather than process water. This invention can reduce the amount of waste liquid generated by 50%. The venturi scrubber 1 is designed with a throat flow rate of 50 to 70 m / s and a washing liquid dosage of 0.5 to 2 L / m3. The main design objectives are to achieve the highest possible dust removal efficiency (90% or higher) and a moderate pressure drop range (2±1 kPa). The washing efficiency requirements for the acid mist are relatively low (50±20%). The air scrubber also plays a role in cooling. Only when the dust concentration and temperature are reduced can the efficient and reliable operation of the subsequent sulfuric acid mist washing system be guaranteed.

[0036] Step S2: Venturi scrubber 2 is used to separate the gas and liquid at the outlet of Venturi scrubber 1. Venturi scrubber 2 uses either a gravity or cyclone type, and is equipped with a demister before the outlet. The demister uses a high-efficiency baffle, not a wire mesh type, to ensure long-term reliable operation. Venturi scrubber 2 is designed to have a separation efficiency of over 99%.

[0037] Step S3: A packed scrubber 3 is used to absorb the acid mist after dust removal. The absorption liquid is process water instead of alkali solution. The empty tower flow rate of the packed tower is preferably 1-2 m / s, the spray density is >30-60 m3 / m2h, and the packing height is 1-3 times the tower diameter. The present invention proposes a design method for the absorption efficiency of sulfuric acid mist aerosol and the packed scrubber 3:

[0038] (1) Assuming that the sulfuric acid mist (l) exists entirely as anhydride SO3 (g) gas before absorption:

[0039] H2SO4(l) = SO3(g) +H2O(g)

[0040] (2) SO3(g) is dissolved by liquid water H2O(l) in the packed scrubber. The dissolution process follows Henry's Law and distillation theory:

[0041] SO3(g) + H2O(l) = SO3*H2O(l)

[0042] (3) The SO3*H2O(l) solution containing dissolved sulfur trioxide SO3(g) undergoes the following chemical reaction in the tower bottom:

[0043] SO3*H2O(l) = H2SO4(l)

[0044] The following electrochemical equilibrium occurs at the same time:

[0045] H2SO4(l) = HSO4 - + H +

[0046] HSO4- = SO4 2- + H +

[0047] Assuming the above reaction process occurs only in the tower kettle and not in any other stages, this reduces the computational effort while also preventing inflated calculation efficiency. Packed scrubber 3 is designed to achieve a sulfuric acid mist scrubbing efficiency of >95%, with an overall scrubbing efficiency of 98% to 99% at its highest. The sulfuric acid mist concentration discharged into the ambient air is <10 mg / m³.

[0048] Step S4: After a small portion of the absorbed liquid is discharged after the reaction, most of it is recycled back to the top of the tower. The concentration of sulfuric acid gradually accumulates to the designed concentration and is then discharged. The above process is iterated until convergence.

[0049] After calculation, the parameters of the high-concentration sulfuric acid mist packed scrubber 3 designed according to the above assumptions and calculation steps are close to those of the conventional packed scrubber 3 in the sulfuric acid plant, especially the packing height, which proves the effectiveness of the above design method.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. An acidolysis tail gas treatment device, characterized in that: The invention comprises a venturi scrubber (1), a gas-liquid separator (2), a packing scrubber (3), an induced draft fan (4) and an exhaust pipe (5), wherein the rear end of the venturi scrubber (1) is provided with a gas-liquid separator (2), the rear end of the gas-liquid separator (2) is provided with a packing scrubber (3), the rear end of the packing scrubber (3) is provided with an induced draft fan (4), and the rear end of the induced draft fan (4) is provided with an exhaust pipe (5); The venturi scrubber (1) comprises a scrubber body and a venturi circulation pump (11), wherein the body is composed of an anti-clogging nozzle, a contraction section, a throat pipe, and a diffusion section; The gas-liquid separator (2) is composed of components including a gas-liquid separator body, a demister, and a liquid level detection and control instrument. The demister is designed to be a baffle type that prevents scaling and clogging. The gas-liquid separator (2) in the Venturi scrubber (1) uses a centrifugal air intake method to improve the separation effect by using a centrifuge. The packed washing tower (3) is composed of components including a packed washing tower body, packing, a spray distributor, a demister, a washing tower circulation pump (31), a washing tower discharge pipe (32), and a liquid level detection and control instrument.

2. The acidolysis tail gas treatment device according to claim 1, characterized in that: The packed washing tower (3) uses process water as an absorption liquid, and the washing tower discharge pipe (32) is connected to a venturi washing unit, which does not use process water.

3. The acidolysis tail gas treatment device according to claim 1, characterized in that: The gas-liquid separator (2) is of gravity type or cyclone type, and a demister is provided before the outlet of the gas-liquid separator (2).

4. The acidolysis tail gas treatment device according to claim 3, characterized in that: The demister is of high-efficiency baffle type.

5. The acidolysis tail gas treatment device according to claim 1, characterized in that: The anti-clogging nozzle comprises a stainless steel nozzle (101), a storage tank (102) and a semicircular protrusion (103). The stainless steel nozzle (101) is installed at the end of the anti-clogging nozzle. The storage tank (102) is provided on the inner wall of the stainless steel nozzle (101). Several groups of semicircular protrusions (103) are equidistantly connected in the storage tank (102).

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