System for harmlessly producing lithium carbonate raw material from overhaul slag

Abstract

The utility model discloses a system for harmlessly producing a lithium carbonate raw material from overhaul slag, which comprises a raw material preparation system, a raw material reaction system, a blank making system and a firing system, a system discharging port of the raw material reaction system is connected with a system feeding port of the blank making system, and a system discharging port of the blank making system is connected with a system feeding port of the firing system. The system has the advantages that through the arrangement of the system, overhaul slag raw materials are fed into the raw material preparation system 1 to be crushed and ground into powder, then the powder enters the raw material reaction system 2, chemicals and water are added, the mixture is mixed into mud, the mud is fed into the blank making system 3 to be made into green bricks, finally the green bricks are fired in the firing system 4, and the green bricks can be directly used and also serve as raw materials for extracting lithium carbonate.

Description

Technical Field:

[0001] The utility model relates to the field of solid waste treatment, and particularly relates to a system for harmless production of lithium carbonate raw materials from overhaul slag. Background Art:

[0002] During the production of electrolytic aluminum, the cathode material of the electrolytic cell directly contacts with the corrosive electrolyte and molten aluminum at a temperature above 950°C. After the aluminum electrolytic cell operates for a period of time, as the electrolyte and molten aluminum continuously erode deeper, it is necessary to stop the cell for overhaul and replace the used cathode material and refractory insulation material. The overhaul slag of the aluminum electrolytic cell contains soluble fluorides and cyanides. Among them, the soluble fluorides are highly corrosive and belong to harmful substances, and the cyanides are highly toxic substances.

[0003] At present, the harmless treatment process for overhaul slag is relatively mature. After the overhaul slag is harmlessly treated, it is usually used as raw material for cement or brick making. However, valuable elements such as lithium, aluminum, fluorine, and silicon in the overhaul slag have not been effectively recycled. In recent years, industrial production has found that after the overhaul slag is harmlessly treated, it contains lithium carbonate inside. After the lithium carbonate is further extracted, it can be applied in fields such as lithium batteries, glass, and ceramics, and has broad market demand. Therefore, the product after the harmless treatment of the overhaul slag can be used as raw material for extracting lithium carbonate. At present, the industry is exploring relevant process technologies.

[0004] However, there is still a lack of a complete production system for harmlessly treating the overhaul slag and making it into a product for extracting lithium carbonate raw materials. Content of the Utility Model:

[0005] The purpose of the utility model is to provide a system for harmless production of lithium carbonate raw materials from overhaul slag.

[0006] The utility model is implemented by the following technical solutions:

[0007] A system for harmless production of lithium carbonate raw materials from overhaul slag includes a raw material preparation system, a raw material reaction system, a billet making system, and a firing system. The system discharge port of the raw material preparation system is connected to the system feed port of the raw material reaction system, the system discharge port of the raw material reaction system is connected to the system feed port of the billet making system, and the system discharge port of the billet making system is connected to the system feed port of the firing system.

[0008] Preferably, the raw material preparation system includes a raw material conveyor, a raw material feeder, a crusher, a screening machine, a process conveyor, and a ball mill;

[0009] The discharge end of the raw material conveyor is connected to the inlet of the raw material feeder. The outlet of the raw material feeder is connected to the inlet of the crusher. The outlet of the crusher is connected to the inlet of the screening machine. The oversize outlet of the screening machine is connected to the feeding end of the process conveyor. The discharge end of the process conveyor is connected to the inlet of the ball mill. The outlet of the ball mill is the system discharge outlet of the raw material preparation system.

[0010] Preferably, a return conveyor is further included. The undersize outlet of the screening machine is connected to the feeding end of the return conveyor. The discharge end of the return conveyor is connected to the inlet of the crusher.

[0011] Preferably, the raw material reaction system includes a powder bin, a dry powder metering bin, a reaction tank, a desulfurized gypsum tank, a calcium carbonate tank, a reservoir, and a mixing feeder. The inlet of the powder bin is the system inlet of the raw material reaction system. The outlet of the powder bin is connected to the inlet of the dry powder metering bin. The outlets of the dry powder metering bin, the desulfurized gypsum tank, the calcium carbonate tank, and the reservoir are respectively connected to the inlet of the reaction tank. The outlet of the reaction tank is connected to the inlet of the mixing feeder. The outlet of the mixing feeder is the system discharge outlet of the raw material reaction system.

[0012] Preferably, the brick making system includes a brick extrusion machine, a brick cutting machine, and a brick stacking machine. The inlet of the brick extrusion machine is the system inlet of the brick making system. The outlet of the brick extrusion machine is connected to the inlet of the brick cutting machine. The finished product outlet of the brick cutting machine is connected to the inlet of the brick stacking machine. The outlet of the brick stacking machine is the system discharge outlet of the brick making system.

[0013] Preferably, a waste conveyor is further included. The waste outlet of the brick cutting machine is connected to the feeding end of the waste conveyor. The discharge end of the waste conveyor is connected to the inlet of the brick extrusion machine.

[0014] Preferably, the firing system includes a kiln car, a wet brick moisture preservation storage box, a drying kiln, and a roasting kiln. The inlet of the kiln car is the system inlet of the firing system. The inlets and outlets of the wet brick moisture preservation storage box, the drying kiln, and the roasting kiln are sequentially connected in series by tracks. The kiln car slides through the tracks and is placed inside the wet brick moisture preservation storage box, the drying kiln, and the roasting kiln.

[0015] The wet green body moisture preservation storage box includes a housing, a water tank, a water outlet pump, a three-way valve, a spray pipe, an induced draft fan, a heat exchanger, a return water pump, and an atomizing pipe. The two ends of the housing are provided with an inlet and an outlet. The water tank is fixed to the top of the housing. The outlet of the water tank is connected to the inlet of the water outlet pump. The outlet of the water outlet pump is connected to the first port of the three-way valve. The second port of the three-way valve passes through the top of the housing and is communicated with the spray pipe. The second port of the three-way valve is connected to the material inlet of the heat exchanger. The steam outlet of the heat exchanger is connected to the inlet of the induced draft fan. The outlet of the induced draft fan passes through the side wall of the housing and is communicated with the atomizing pipe. The spray pipe is arranged above the interior of the housing. The atomizing pipes are two and are arranged on both sides of the interior of the housing. The condensate inlet of the heat exchanger is connected to the inlet of the return water pump. The outlet of the return water pump is communicated with the top of the housing. The heat exchange medium inlet and outlet of the heat exchanger are communicated with the flue of the drying kiln.

[0016] Advantages of the present utility model: 1. In this system, the overhaul slag is used as a raw material and sent to the raw material preparation system for crushing and grinding to form a powder. Then, it enters the raw material reaction system, where chemicals and water are added and mixed to form a mud-like substance. After that, it is sent to the brick blank forming system to form brick blanks, and finally, it is fired into bricks in the firing system. In this process, harmful substances such as cyanide and fluoride in the waste slag are converted into non-toxic products through high-temperature decomposition. The bricks can be directly sold externally or used as raw materials for extracting lithium carbonate.

[0017] 2. Before the brick blanks are fired, instead of the traditional spray moisturization, the waste heat of the flue gas is utilized to turn the water into steam for moisturization, and the water vaporization is evenly distributed, with a good moisturization effect. Description of the drawings:

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is a schematic diagram of the overall structure of the present utility model;

[0020] Figure 2 is a schematic diagram of the structure of the wet green body moisture preservation storage box of the present utility model;

[0021] Figure 3 is a side view of the housing and the internal structure of the wet green body moisture preservation storage box of the present utility model.

[0022] In the figure: raw material preparation system 1, raw material conveyor 1.1, raw material feeder 1.2, crusher 1.3, screening machine 1.4, process conveyor 1.5, ball mill 1.6, return conveyor 1.7, raw material reaction system 2, powder silo 2.1, dry powder metering silo 2.2, reaction tank 2.3, desulfurized gypsum tank 2.4, calcium carbonate tank 2.5, water tank 2.6, mixing feeder 2.7, blank making system 3, making Brick extruder 3.1, brick making and cutting machine 3.2, brick stacking machine 3.3, waste conveyor 3.4, firing system 4, kiln car 4.1, wet brick moisturizing storage box 4.2, shell 4.21, water tank 4.22, water outlet pump 4.23, three-way valve 4.24, spray pipe 4.25, induced draft fan 4.26, heat exchanger 4.27, return water pump 4.28, atomizing pipe 4.29, drying kiln 4.3, roasting kiln 4.4. Specific implementation method:

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, a system for harmlessly producing lithium carbonate raw materials from overhaul slag includes a raw material preparation system 1, a raw material reaction system 2, a billet making system 3, and a firing system 4. The system discharge port of the raw material preparation system 1 is connected to the system feed port of the raw material reaction system 2, the system discharge port of the raw material reaction system 2 is connected to the system feed port of the billet making system 3, and the system discharge port of the billet making system 3 is connected to the system feed port of the firing system 4.

[0025] The raw material is overhaul slag, which enters the raw material preparation system 1 for crushing and grinding into powder, and then enters the raw material reaction system 2 to add reagents and water and mix to form a mud-like substance, and then is sent to the blank making system 3 to be made into brick blanks, and finally is fired into bricks in the firing system 4, which can be used directly and is also used as a raw material for extracting lithium carbonate.

[0026] The raw material preparation system 1 includes a raw material conveyor 1.1, a raw material feeder 1.2, a crusher 1.3, a screening machine 1.4, a process conveyor 1.5, and a ball mill 1.6;

[0027] The discharge end of the raw material conveyor 1.1 is connected to the inlet of the raw material feeder 1.2. The outlet of the raw material feeder 1.2 is connected to the inlet of the crusher 1.3. The outlet of the crusher 1.3 is connected to the inlet of the screening machine 1.4. The oversize outlet of the screening machine 1.4 is connected to the feeding end of the process conveyor 1.5. The discharge end of the process conveyor 1.5 is connected to the inlet of the ball mill 1.6. The outlet of the ball mill 1.6 is the system discharge outlet of the raw material preparation system 1.

[0028] The raw materials are sent to the raw material feeder 1.2 through the raw material conveyor 1.1, and fed to the crusher 1.3 through the raw material feeder 1.2. The raw materials, which are large pieces of overhaul slag with irregular shapes and inconsistent sizes, are crushed into small pieces with relatively close shapes and sizes. The diameter of the raw material particles needs to be below 2.0 mm. Then, they enter the screening machine 1.4 for screening. The particles with a diameter below 2.0 mm are sent to the ball mill 1.6 by the process conveyor 1.5 and ground into powder.

[0029] It also includes a return conveyor 1.7. The undersize outlet of the screening machine 1.4 is connected to the feeding end of the return conveyor 1.7. The discharge end of the return conveyor 1.7 is connected to the inlet of the crusher 1.3.

[0030] The coarse materials with a screening particle size exceeding 2.0 mm are conveyed by the return conveyor 1.7 to the crusher 1.3 for secondary crushing until the particle size is qualified.

[0031] The raw material reaction system 2 includes a powder silo 2.1, a dry powder metering bin 2.2, a reaction tank 2.3, a desulfurized gypsum tank 2.4, a calcium carbonate tank 2.5, a reservoir 2.6, and a mixing feeder 2.7. The inlet of the powder silo 2.1 is the system inlet of the raw material reaction system 2. The outlet of the powder silo 2.1 is connected to the inlet of the dry powder metering bin 2.2. The outlets of the dry powder metering bin 2.2, the desulfurized gypsum tank 2.4, the calcium carbonate tank 2.5, and the reservoir 2.6 are respectively connected to the inlet of the reaction tank 2.3. The outlet of the reaction tank 2.3 is connected to the inlet of the mixing feeder 2.7. The outlet of the mixing feeder 2.7 is the system outlet of the raw material reaction system 2.

[0032] The overhaul slag powder is stored in the powder silo 2.1 and sent to the reaction tank 2.3 by weighing through the dry powder metering bin 2.2. At the same time, the desulfurized gypsum is weighed from the desulfurized gypsum tank 2.4, the calcium carbonate is weighed from the calcium carbonate tank 2.5 and sent to the reaction tank 2.3, and the water in the reservoir 2.6 is also poured into the reaction tank 2.3 for stirring and mixing. The best ratio of the overhaul slag powder, desulfurized gypsum, and calcium carbonate is 1:0.4:0.2, and the moisture content is controlled at about 17%. As long as the material performance meets the forming requirements, the mixed material is in a mud-like state and enters the mixing feeder 2.7. Among them, the reaction tank 2.3 is provided with stirring blades and a motor on the tank body.

[0033] The blank-making system 3 includes a brick-making extruder 3.1, a brick-making strip cutter 3.2, and a brick stacking machine 3.3. The inlet of the brick-making extruder 3.1 is the system feed inlet of the blank-making system 3. The outlet of the brick-making extruder 3.1 is connected to the inlet of the brick-making strip cutter 3.2. The finished product outlet of the brick-making strip cutter 3.2 is connected to the inlet of the brick stacking machine 3.3. The outlet of the brick stacking machine 3.3 is the system discharge outlet of the blank-making system 3.

[0034] The mixed material enters the brick-making extruder 3.1 for extrusion and is made into brick blanks by the brick-making strip cutter 3.2. The specifications of the brick blanks are preferably 6-hole hollow bricks with dimensions of 240×120×90 mm. When making the brick blanks, the blank body is also subjected to treatments such as scraping and chamfering.

[0035] It also includes a waste conveyor 3.4. The waste product outlet of the brick-making strip cutter 3.2 is connected to the feed end of the waste conveyor 3.4. The discharge end of the waste conveyor 3.4 is connected to the inlet of the brick-making extruder 3.1. The trimmed waste blanks and the discarded brick blanks are sent by the waste conveyor 3.4 to the brick-making extruder 3.1 for reuse.

[0036] The firing system 4 includes a kiln car 4.1, a wet blank humidity-preserving storage box 4.2, a drying kiln 4.3, and a roasting kiln 4.4. The inlet of the kiln car 4.1 is the system feed inlet of the firing system 4. The inlets and outlets of the wet blank humidity-preserving storage box 4.2, the drying kiln 4.3, and the roasting kiln 4.4 are sequentially connected in series by tracks. The kiln car 4.1 slides through the tracks and is placed inside the wet blank humidity-preserving storage box 4.2, the drying kiln 4.3, and the roasting kiln 4.4.

[0037] Both the drying kiln 4.3 and the roasting kiln 4.4 are tunnel kilns, so there are tracks provided. The kiln is divided into a drying section, a roasting section, and a cooling section.

[0038] For full heat utilization, the drying heat source comes from the waste heat of the roasting kiln 4.4. Since the cross-sectional area of the drying section is large and the smoke velocity is low, the flue gas meanders in the chamber. Therefore, a large amount of soot can be intercepted in the drying section. By introducing the flue gas of the roasting kiln 4.4 into the drying kiln 4.3 to utilize the waste heat, the soot emissions in the flue gas can be effectively reduced.

[0039] The brick stacking machine 3.3 stacks the blank bodies onto the kiln car 4.1. The kiln car 4.1 carries about 11.5 tons of brick blanks and first enters the drying kiln 4.3 through the tracks for preheating and drying, and then enters the roasting kiln 4.4 for firing. The roasting kiln 4.4 uses natural gas as fuel for roasting. The roasting temperature is controlled at 850 - 1200 °C, and the roasting time is more than 20 min. The entire roasting system is automatically controlled through the control room to ensure that the firing temperature of the brick blanks reaches above 1000 °C, and the brick blanks stay in the kiln for an average of 30 min to ensure that toxic and harmful substances are fully decomposed and vaporized at high temperatures.

[0040] The firing process proceeds slowly. The rear kiln car 4.1 can carry the green bricks and first keep them moist in the green brick moisture storage box 4.2 to prevent moisture loss and surface cracking.

[0041] The green brick moisture storage box 4.2 includes a housing 4.21, a water tank 4.22, a water outlet pump 4.23, a three-way valve 4.24, a spray pipe 4.25, an induced draft fan 4.26, a heat exchanger 4.27, a return water pump 4.28, and an atomizing pipe 4.29. There are an inlet and an outlet at both ends of the housing 4.21. The water tank 4.22 is fixed on the top of the housing 4.21. The outlet of the water tank 4.22 is connected to the inlet of the water outlet pump 4.23. The outlet of the water outlet pump 4.23 is connected to the first port of the three-way valve 4.24. The second port of the three-way valve 4.24 passes through the top of the housing 4.21 and is communicated with the spray pipe 4.25. The second port of the three-way valve 4.24 is connected to the material inlet of the heat exchanger 4.27. The steam outlet of the heat exchanger 4.27 is connected to the inlet of the induced draft fan 4.26. The outlet of the induced draft fan 4.26 passes through the side wall of the housing 4.21 and is communicated with the atomizing pipe 4.29. The spray pipe 4.25 is arranged above the inside of the housing 4.21.

[0042] The kiln car 4.1 enters the housing 4.21 from the track and stays. The water in the water tank 4.22 is pumped out by the water outlet pump 4.23, passes through the three-way valve 4.24 and is communicated with the spray pipe 4.25, and the water is sprayed and drops, which can keep the green bricks moist.

[0043] There are two atomizing pipes 4.29 arranged on both sides inside the housing 4.21. The condensate inlet of the heat exchanger 4.27 is connected to the inlet of the return water pump 4.28. The outlet of the return water pump 4.28 is communicated with the top of the housing 4.21. The heat transfer medium inlet and outlet of the heat exchanger 4.27 are communicated with the flue of the drying kiln 4.3.

[0044] Or the pumped-out water passes through the three-way valve 4.24 and is communicated with the heat exchanger 4.27. The temperature of the flue gas after drying in the drying kiln 4.3 is also very high and can be used for heat exchange to turn the water into steam. The steam is blown to the atomizing pipe 4.29 by the negative pressure of the induced draft fan 4.26 and rises. It can not only keep the green bricks moist but also increase the temperature to some extent. The water is vaporized and evenly distributed, and the moisture retention effect is good. The water that is not evaporated or condensed is sent back to the water tank 4.22 through the return water pump 4.28.

[0045] Working principle: When in use, the overhaul slag raw materials are sent to the raw material feeder 1.2 through the raw material conveyor 1.1, and are fed to the crusher 1.3 by the raw material feeder 1.2 to break the large overhaul slag into small pieces. Then, it enters the screening machine 1.4 for screening. The particles with a diameter less than 2.0 mm are sent to the ball mill 1.6 by the process conveyor 1.5 and ground into powder.

[0046] The overhaul slag powder is stored in the powder bin 2.1, weighed by the dry powder metering bin 2.2 and sent into the reaction tank 2.3. At the same time, desulfurized gypsum and calcium carbonate are sent into the reaction tank 2.3, and then water is added for stirring and mixing. The optimal ratio of overhaul slag powder, desulfurized gypsum and calcium carbonate is 1:0.4:0.2, and the moisture content is controlled at about 17%. The mixed material in a mud state enters the mixed material feeder 2.7.

[0047] The mixed material enters the brick-making extruder 3.1 for extrusion and is made into brick blanks by the brick-making strip cutter 3.2. The specification of the brick blanks is preferably a 6-hole hollow brick with the size of 240×120×90mm. When making the brick blanks, the blank body is also subjected to scraping, chamfering and other treatments, and then the blank body is stacked on the kiln car 4.1 by the blank stacking machine 3.3. The kiln car 4.1 carries about 11.5 tons of brick blanks and first enters the drying kiln 4.3 through the track for preheating and drying, and then enters the roasting kiln 4.4 for firing. The roasting kiln 4.4 uses natural gas as fuel for roasting, the roasting temperature is controlled at 850-1200°C, and the roasting time is more than 20 minutes. The whole roasting system is automatically controlled through the control room to ensure that the firing temperature of the brick blanks reaches more than 1000°C, and the average residence time of the brick blanks in the kiln is 30 minutes to ensure that toxic and harmful substances are fully decomposed and vaporized at high temperature.

[0048] The firing process proceeds slowly. The subsequent kiln car 4.1 can carry the brick blanks to be moisturized in the wet blank moisturizing storage box 4.2 to prevent moisture loss and surface cracking.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for harmlessly producing lithium carbonate raw materials from overhaul slag, characterized in that, It includes a raw material preparation system, a raw material reaction system, a brick blank making system, and a firing system. The system discharge port of the raw material preparation system is connected to the system feed port of the raw material reaction system. The system discharge port of the raw material reaction system is connected to the system feed port of the brick blank making system. The system discharge port of the brick blank making system is connected to the system feed port of the firing system.

2. The system for harmlessly producing lithium carbonate raw materials from overhaul slag according to claim 1, wherein: The raw material preparation system includes a raw material conveyor, a raw material feeder, a crusher, a screening machine, a process conveyor, and a ball mill; The discharge end of the raw material conveyor is connected to the inlet of the raw material feeder. The outlet of the raw material feeder is connected to the inlet of the crusher. The outlet of the crusher is connected to the inlet of the screening machine. The oversize outlet of the screening machine is connected to the feed end of the process conveyor. The discharge end of the process conveyor is connected to the inlet of the ball mill. The outlet of the ball mill is the system discharge port of the raw material preparation system.

3. The system for harmless production of lithium carbonate raw materials from overhaul slag according to claim 2, wherein: It further includes a return conveyor. The undersize outlet of the screening machine is connected to the feed end of the return conveyor. The discharge end of the return conveyor is connected to the inlet of the crusher.

4. A system for harmlessly producing lithium carbonate raw materials from overhaul slag according to claim 1 or 3, characterized in that: The raw material reaction system includes a powder bin, a dry powder metering bin, a reaction tank, a desulfurized gypsum tank, a calcium carbonate tank, a water storage tank, and a mixing feeder. The inlet of the powder bin is the system feed port of the raw material reaction system. The outlet of the powder bin is connected to the inlet of the dry powder metering bin. The outlets of the dry powder metering bin, the desulfurized gypsum tank, the calcium carbonate tank, and the water storage tank are respectively connected to the inlet of the reaction tank. The outlet of the reaction tank is connected to the inlet of the mixing feeder. The outlet of the mixing feeder is the system discharge port of the raw material reaction system.

5. A system for harmless production of lithium carbonate raw materials from overhaul slag according to claim 4, characterized in that: The brick blank making system includes a brick extrusion machine, a brick cutting machine, and a brick stacking machine. The inlet of the brick extrusion machine is the system feed port of the brick blank making system. The outlet of the brick extrusion machine is connected to the inlet of the brick cutting machine. The finished product outlet of the brick cutting machine is connected to the inlet of the brick stacking machine. The outlet of the brick stacking machine is the system discharge port of the brick blank making system.

6. The system for harmless production of lithium carbonate raw materials from overhaul slag according to claim 5, characterized in that: It further includes a waste conveyor. The waste product outlet of the brick cutting machine is connected to the feed end of the waste conveyor. The discharge end of the waste conveyor is connected to the inlet of the brick extrusion machine.

7. The system for harmless production of lithium carbonate raw materials from overhaul slag according to claim 6, characterized in that: The firing system includes a kiln car, a wet brick moisture preservation storage box, a drying kiln, and a roasting kiln. The inlet of the kiln car is the system feed port of the firing system. The inlets and outlets of the wet brick moisture preservation storage box, the drying kiln, and the roasting kiln are sequentially connected in series by tracks. The kiln car slides inside the wet brick moisture preservation storage box, the drying kiln, and the roasting kiln through the tracks; The wet green body moisture preservation storage box includes a housing, a water tank, a water outlet pump, a three-way valve, a spray pipe, an induced draft fan, a heat exchanger, a return water pump, and an atomizing pipe. The two ends of the housing are provided with an inlet and an outlet. The water tank is fixed to the top of the housing. The outlet of the water tank is connected to the water inlet of the water outlet pump. The water outlet of the water outlet pump is connected to the first port of the three-way valve. The second port of the three-way valve penetrates through the top of the housing and is communicated with the spray pipe. The second port of the three-way valve is connected to the material inlet of the heat exchanger. The steam outlet of the heat exchanger is connected to the inlet of the induced draft fan. The outlet of the induced draft fan penetrates through the side wall of the housing and is communicated with the atomizing pipe. The spray pipe is arranged above the interior of the housing. The atomizing pipes are two and are arranged on both sides of the interior of the housing. The condensate inlet of the heat exchanger is connected to the water inlet of the return water pump. The water outlet of the return water pump is communicated with the top of the housing. The heat transfer medium inlet and outlet of the heat exchanger are communicated with the flue of the drying kiln.

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