HCl tail gas recycling system for anhydrous magnesium chloride production
By designing the HCl exhaust gas recycling system, the problem of incomplete exhaust gas purification in the production of anhydrous magnesium chloride is solved, the recycling of exhaust gas and efficient recycling of resources are achieved, the production costs and environmental pollution are reduced, and the environmental protection of the production equipment is improved.
Patent Information
- Application Number
- CN202421433109.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-21
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2034-06-21
AI Technical Summary
During the production process of anhydrous magnesium chloride, the traditional purification treatment of HCl exhaust cannot be completely absorbed, resulting in environmental pollution and waste of resources and increasing production costs.
A HCl exhaust gas recycling system was designed. After cooling, purification, dehumidification and heating of the exhaust gas, it was circulated back to the drying device, and the circulation pipeline and low-concentration magnesium chloride solution were used as cooling medium to achieve effective utilization of exhaust gas, and Washing is performed in the spray tower to recover magnesium chloride dust and adjust pH.
It reduces the production cost of anhydrous magnesium chloride, reduces exhaust gas emissions, improves the environmental friendliness of the production equipment, and realizes the utilization of waste heat and material recycling.
Smart Images
Figure CN222219050U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of industrial production of anhydrous magnesium chloride, in particular to a HCl tail gas recycling system for the production of anhydrous magnesium chloride. Background Art
[0002] Anhydrous magnesium chloride is the main raw material for producing magnesium metal by electrolysis. At present, the most mature magnesium chloride dehydration and granulation process at home and abroad is commonly used in multi-step dehydration. The process of preparing anhydrous magnesium chloride by multi-step dehydration is generally carried out in a multi-stage drying device, such as a fluidized bed. The granulation of magnesium chloride is first completed by a granulating device to generate hexahydrate magnesium chloride from a magnesium chloride solution, and then the hexahydrate magnesium chloride is dehydrated to generate dihydrate magnesium chloride by a primary drying device, and finally anhydrous magnesium chloride is generated from dihydrate magnesium chloride by a secondary drying device. Among them, when anhydrous magnesium chloride is produced in a secondary drying device, in order to avoid the generation of basic magnesium chloride during the dehydration process, the entire drying and dehydration process needs to be carried out in an HCl atmosphere. After the wet HCl tail gas is discharged after the heat exchange in the drying device, it is still unable to completely absorb the HCl gas through traditional washing and purification treatment, and the environmental pollution after discharge is relatively serious, and the HCl gas is directly purified and disposed of, which is relatively wasteful, resulting in an increase in the cost of anhydrous magnesium chloride production. Utility Model Content
[0003] In order to solve the problems in the prior art, the utility model patent designs a HCl tail gas recycling system for the production of anhydrous magnesium chloride. After the HCl tail gas is purified, it is continued to be sent to the drying device as a heating atmosphere to achieve the recycling of the HCl gas.
[0004] The technical solution adopted by the utility model is: the exhaust gas recycling system comprises an exhaust gas cooling device, an exhaust gas washing device, an exhaust gas dehumidification device, a circulating fan and an exhaust gas heating device which are sequentially connected by pipelines, the air inlet end pipeline of the exhaust gas cooling device is connected to the exhaust port of the anhydrous magnesium chloride drying device, and the air outlet end pipeline of the exhaust gas heating device is connected to the air inlet of the drying device.
[0005] Furthermore, the exhaust gas cooling device is a quench cooler, and an exhaust gas circulation pipeline and a cooling medium circulation pipeline are arranged in the quench cooler.
[0006] Furthermore, the tail gas scrubbing device is a spray tower, which is provided with a circulating spray device, which includes a circulating pump, a circulating pipeline and multiple spray heads, the liquid inlet end of the circulating pump is connected to the liquid inlet pipeline through a three-way valve, the liquid inlet pipeline is connected to a low-concentration magnesium chloride solution storage tank, and the liquid outlet end of the circulating pump is connected to an external transmission pipeline through a three-way valve.
[0007] Furthermore, the exhaust gas dehumidification device includes a heat exchanger and a condenser connected in sequence, and the liquid outlet ends of the heat exchanger and the condenser are connected to a condensed water collection pipeline.
[0008] Furthermore, the cooling medium circulation pipeline of the quench cooler is connected in series with the cooling medium circulation pipeline of the heat exchanger, and the cooling medium is a low-concentration magnesium chloride solution.
[0009] Furthermore, the HCl tail gas recycling system is further provided with an HCl gas preheater upstream of the circulating fan.
[0010] Furthermore, the tail gas heating device is a gas-fired heating furnace, and the temperature of the HCl gas outlet of the gas-fired heating furnace is maintained at 200-300°C.
[0011] Furthermore, the external transmission pipeline of the circulation pump is connected to the flash tank, and the steam output end of the flash tank merges with the tail gas output pipeline of the spray tower.
[0012] Compared with the prior art, the improvement of the HCl tail gas recycling system for anhydrous magnesium chloride production designed by the utility model patent is:
[0013] The utility model adopts a circulation pipeline to cool, purify, dehumidify and heat the HCl tail gas discharged from the drying device and then send it back to the drying device, thereby realizing the recycling of the HCl gas, reducing the production cost of anhydrous magnesium chloride, and at the same time reducing the emission of tail gas, greatly improving the environmental friendliness of the production device.
[0014] The utility model has cooling medium flow pipelines of a quench cooler and a heat exchanger connected in series, and uses a low-concentration magnesium chloride solution as a cooling medium. The utility model is particularly suitable for a production process for preparing anhydrous magnesium chloride by a one-step method, and can use the waste heat of HCl tail gas to preheat the low-concentration magnesium chloride solution, thereby improving the concentration efficiency of the solution and achieving the purpose of waste heat utilization.
[0015] The spray tower of the tail gas washing device of the utility model washes and absorbs the fine magnesium chloride dust entrained in the tail gas, and the washing liquid with increased concentration after spraying is sent to the flash tank to prepare a high-concentration magnesium chloride solution, thereby realizing the simultaneous operation of tail gas washing and material recovery. The flash tank also removes the HCl dissolved in the solution and adjusts the pH value of the solution to avoid corrosion to subsequent process equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a structural schematic diagram of the HCl tail gas recycling system in the production of anhydrous magnesium chloride.
[0017] In the figure, 1 is a fluidized bed, 2 is a quench cooler, 3 is a spray tower, 4 is a flash tank, 5 is a heat exchanger, 6 is a condenser, 7 is a hydrochloric acid analysis system, 8 is a preheater, 9 is a circulating fan, 10 is a gas heating furnace, 31 is a circulating spray device, and 32 is a circulating pump. DETAILED DESCRIPTION
[0018] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments. The technical solutions in the embodiments of the utility model are clearly and completely described, and the described embodiments are only embodiments of a part of the utility model patent, not all of them. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0019] like Figure 1 As shown, the utility model patent designs an embodiment of an HCl tail gas recycling system for anhydrous magnesium chloride production. The tail gas recycling system in this embodiment is particularly suitable for a one-step production process for anhydrous magnesium chloride, including a tail gas cooling device, a tail gas washing device, a tail gas dehumidification device, a preheater 8, a circulating fan 9 and a tail gas heating device connected in sequence by pipelines. The air inlet end pipeline of the tail gas cooling device is connected to the exhaust port of the drying device of anhydrous magnesium chloride, and the air outlet end pipeline of the tail gas heating device is connected to the air inlet of the drying device 1.
[0020] In this embodiment, the drying device is a fluidized bed 1, the exhaust gas cooling device is a quench cooler 2, the exhaust gas washing device is a spray tower 3, the exhaust gas dehumidification device is a series heat exchanger 5 and a condenser 6, and the exhaust gas heating device is a gas heating furnace 10.
[0021] The fluidized bed 1 uses a spray granulation method to dehydrate and granulate the high-concentration magnesium chloride solution, and uses HCl gas as the heating atmosphere. The air inlet end of the quench cooler 2 of the HCl tail gas recycling system is connected to the exhaust port of the fluidized bed 1, and the air outlet end of the gas heating furnace 10 is connected to the air inlet at the bottom of the fluidized bed 1.
[0022] An exhaust gas circulation pipeline and a cooling medium circulation pipeline are arranged in the quench cooler 2, and the inlet and outlet ends of the exhaust gas circulation pipeline are connected to the fluidized bed 1 and the spray tower 3 respectively.
[0023] The spray tower 3 is provided with a circulating spray device 31, which includes a circulating pump 32, a circulating pipeline and a plurality of spray heads. The circulating pipeline is provided with pressure by the circulating pump 32, and the spray head is arranged on the upper side of the spray tower 3. The liquid inlet end of the circulating pump 32 is connected to the liquid inlet pipeline through a three-way valve to regularly input new washing liquid, and the liquid outlet end of the circulating pump 32 is connected to the external transmission pipeline through a three-way valve, and the external transmission pipeline is connected to the flash tank 4, which can regularly transport the spray washing liquid with increased concentration after washing the tail gas to the flash tank 4 to produce a high-concentration magnesium chloride solution. The steam output end of the flash tank 4 is combined with the tail gas output pipeline of the spray tower 3 and then input into the heat exchanger 5 together.
[0024] The liquid outlets of the heat exchanger 5 and the condenser 6 are connected to a condensate collection pipeline, which is connected to a hydrochloric acid analysis system 7. The water vapor entrained in the tail gas after spray washing and the steam discharged from the flash tank 4 are removed by step cooling. HCl is dissolved in the condensed water formed after cooling. The condensed water is collected and input into the hydrochloric acid analysis system 7 for HCl recovery. The heat exchanger 5 is connected in series with the cooling medium flow pipeline of the quencher 2, and a low-concentration magnesium chloride solution is used as the cooling medium. The heating pipeline can be used as a waste heat to preheat the low-concentration magnesium chloride solution, thereby improving the evaporation and concentration efficiency of the magnesium chloride solution.
[0025] The preheater 8 preheats the purified and dehumidified HCl tail gas, and the circulating fan 9 provides negative pressure power for the circulation of the HCl tail gas, and sends the preheated HCl tail gas to the gas-fired heating furnace 10, and the gas-fired heating furnace 10 further heats and raises the temperature before the preheated HCl tail gas enters the fluidized bed 1 again, completing the recycling of the HCl tail gas. A branch line is also provided at the air inlet end of the gas-fired heating furnace 10 to supplement the HCl gas.
[0026] The above contents are only preferred embodiments of the present invention and cannot be used to limit the scope of implementation of the present invention. That is, all simple equivalent changes and modifications made according to the claims and description of the present invention are still within the scope of the present invention.
Claims
1. A HCl tail gas recycling system for anhydrous magnesium chloride production, characterized in that: The exhaust gas recycling system comprises an exhaust gas cooling device, an exhaust gas washing device, an exhaust gas dehumidification device, a circulating fan and an exhaust gas heating device which are sequentially connected by pipelines. The air inlet end pipeline of the exhaust gas cooling device is connected to the exhaust port of an anhydrous magnesium chloride drying device, and the air outlet end pipeline of the exhaust gas heating device is connected to the air inlet of the drying device.
2. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 1, characterized in that: The exhaust gas cooling device is a quench cooler, and an exhaust gas circulation pipeline and a cooling medium circulation pipeline are arranged in the quench cooler.
3. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 2, characterized in that: The tail gas scrubbing device is a spray tower, and the spray tower is provided with a circulating spray device, and the circulating spray device includes a circulating pump, a circulating pipeline and a plurality of spray heads.
4. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 3, characterized in that: The liquid inlet end of the circulation pump is connected to a liquid inlet pipeline through a three-way valve, the liquid inlet pipeline is connected to a low-concentration magnesium chloride solution storage tank, and the liquid outlet end of the circulation pump is connected to an external transmission pipeline through a three-way valve.
5. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 4, characterized in that: The tail gas dehumidification device comprises a heat exchanger and a condenser connected in sequence, and the liquid outlet ends of the heat exchanger and the condenser are connected with a condensed water collection pipeline.
6. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 5, characterized in that: The cooling medium circulation pipeline of the quench cooler is connected in series with the cooling medium circulation pipeline of the heat exchanger, and the cooling medium is a low-concentration magnesium chloride solution.
7. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 6, characterized in that: The HCl tail gas recycling system is further provided with an HCl gas preheater upstream of the circulating fan.
8. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 1, characterized in that: The tail gas heating device is a gas-fired heating furnace, and the temperature of the HCl gas outlet of the gas-fired heating furnace is maintained at 200-300°C.
9. The HCl tail gas recycling system for producing anhydrous magnesium chloride according to claim 7, characterized in that: The external transmission pipeline of the circulation pump is connected to the flash tank, and the steam output end of the flash tank is merged with the tail gas output pipeline of the spray tower.