Comprehensive utilization and treatment method and equipment system for ammonia-soda process ammonia wastewater

Abstract

A comprehensive utilization and treatment method and equipment system for ammonia distillation wastewater from the ammonia-soda process includes an evaporation and concentration chamber, a heat pump system, a cooling chamber, a freezing separation chamber, a heat exchanger, an evaporation and crystallization chamber, and a cooling crystallization chamber. Combined with solar radiation, the wastewater undergoes a multi-stage heat exchange cycle through evaporation, cooling and freezing separation, gas-liquid separation, evaporation and crystallization, and cooling crystallization. This process effectively and continuously separates sodium chloride and calcium chloride salts while recovering fresh water. The sodium chloride recovery rate is 75%, the calcium chloride recovery rate is 75%, and the fresh water recovery rate is 55%. This reduces the input cost of raw salt and the amount of mixed solids landfilled in the alkali production process, lowering operating costs. The wastewater can be directly used as lime slurry or, after treatment, as raw water for molten salt, conserving water resources. Through the comprehensive utilization of the wastewater, evaporation efficiency is increased, land area previously occupied by solar pond evaporation of the wastewater is reduced, and the comprehensive utilization of waste resources is maximized.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-stage treatment of IPC classification C02F 9 / 00 water, wastewater or sewage, and relates to a comprehensive utilization technology of industrial waste liquid from an ammonia-soda process. Background Art

[0002] The process of producing soda ash by ammonia-soda process generates a large amount of solid, liquid and gaseous waste, especially the waste liquid and waste residue. According to relevant statistics, the ammonia-soda process produces about 10m3 of waste for every ton of soda ash produced. 3 If the huge amount of waste liquid cannot be treated and utilized in time, it will not only lead to waste of resources but also cause serious environmental pollution.

[0003] Currently, conventional technologies commonly used to treat ammonia evaporation wastewater mainly fall into two categories: evaporation and crystallization to produce calcium chloride, and sodium sulfate processing, which uses sodium sulfate as a raw material to produce calcium sulfate. The former involves naturally evaporating the supernatant from the ammonia evaporation wastewater in a storage tank in salt pans to increase the concentration and produce calcium chloride. This process suffers from low efficiency, long cycle times, instability, and a large footprint. The latter, using sodium sulfate, consumes large amounts of mirabilite, resulting in high treatment costs and poor economic efficiency.

[0004] Some of the improved technology disclosures involve new research and exploration work. For example:

[0005] Chinese patent application CN116040672A discloses a method for preparing basic calcium chloride co-crystals by ammonia evaporation. The ammonia evaporation waste liquid is precipitated to obtain a supernatant and ammonia evaporation waste residue. The supernatant is filtered through a microfiltration and / or ultrafiltration device to obtain an ammonia evaporation waste liquid. A pH adjuster is added to the ammonia evaporation waste liquid. The pH-adjusted alkaline solution is crystallized at low temperature to obtain a solid-liquid mixture. The mixture is filtered to obtain basic calcium chloride crystals and a mother liquor. The basic calcium chloride crystals are dried to obtain a basic calcium chloride eutectic product. The ammonia evaporation waste residue is ground into fine particles, mixed with the mother liquor to obtain a suspension, and the suspension is filtered. The resulting mixed solution is added to the ammonia evaporation waste liquid as a pH adjuster. After filtration, the method adjusts the pH of the solution, controls the temperature at -18-12°C, and performs recrystallization to obtain basic calcium chloride crystals and mother liquor. The obtained basic calcium chloride crystals are dried and ground to obtain the product. After the mother liquor is reused, a portion still needs to be discharged, and the ammonia vapor waste liquid contains 4-6% salt that needs to be separated. The sodium ion content of the raw material in the experiment is lower than 1000 mg / L, indicating that the desalination process not described in the front end must have energy consumption, resulting in the overall process cost being still relatively high.

[0006] Chinese patent application 202310547119.X provides a device and method for resource utilization of alkali ammonia waste liquid, which uses flue gas waste heat to evaporate and concentrate the ammonia waste liquid, and realizes flue gas desulfurization to obtain CaSO4 by-product, and uses the ammonia waste liquid to absorb CO2 to prepare special CaCO3 hollow microspheres, and uses carbonate precipitation method to remove the remaining Ca in the ammonia waste liquid. 2+ Converted into micron CaCO3, Na + The remaining NH4Cl concentrated solution is commercialized as a raw material for liquid fertilizer.

[0007] Chinese patent application 202211662023.X discloses a method for treating ammonia evaporation wastewater, comprising adding sodium sulfate to the ammonia evaporation wastewater to obtain a first mixed solution; adjusting the pH of the first mixed solution to between 6 and 9 to obtain a second mixed solution; and allowing the second mixed solution to stand and separate into layers. The supernatant layer is used for crystallization to recover sodium chloride, and the precipitate layer is stored in an alkali slag dump. Alkali slag dumps cause certain environmental damage.

[0008] The Chinese patent document CN110877941A discloses a "system and method for resource utilization of ammonia evaporation waste liquid by the ammonia-soda process". The system includes a sodium sulfate dissolution tank, a storage tank for the supernatant of the ammonia evaporation waste liquid, a gypsum reaction tank, a gypsum precipitation tank, a filtration device, a freezing crystallization system, a heat exchange device, a gypsum refining system and a nanofiltration system; the steps include: (1) adding a drug to react to obtain a gypsum suspension; (2) primary precipitation of gypsum; (3) secondary precipitation of gypsum; (4) filtering and separating the secondary supernatant; (5) freezing crystallization to remove excess sodium sulfate; (6) freezing mother liquor for heat exchange; (7) nanofiltration for salt separation. Using sodium sulfate, after gypsum reaction, precipitation, filtration, freezing crystallization, heat exchange and other measures, the product gypsum and saline wastewater are obtained for reuse, which consumes a lot of sodium sulfate, and the freezing and subsequent evaporation and heat exchange require a lot of energy, which is costly.

[0009] Most alkali-making industries are located in water source areas or environmentally fragile areas. If a large amount of alkali-making ammonia waste liquid cannot be effectively utilized and is discharged into the natural environment, it will inevitably cause irreversible damage to the local ecosystem. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to propose a comprehensive treatment method for resource utilization of ammonia evaporation waste liquid to recover sodium chloride and water and obtain calcium chloride raw material, as well as a production equipment system for this comprehensive treatment method.

[0011] To this end, the present invention also proposes a comprehensive utilization and treatment method for ammonia-soda process ammonia evaporation waste liquid, which is provided with a heat pump system and combined with solar radiation. The ammonia evaporation waste liquid is subjected to a multi-stage heat exchange cycle treatment through evaporation, cooling and freezing separation, gas-liquid separation, evaporation crystallization and cooling crystallization. While recovering fresh water, sodium chloride and calcium chloride salts are effectively and continuously separated. The composition of the ammonia evaporation waste liquid used is: CaCl2 8-13%, NaCl 4-7%, H2O 75-95%, CaSO4 0.045-0.06%, and Ca(OH)2 0.035-0.055%.

[0012] The treatment process includes: filtering the ammonia waste liquid to obtain a clear liquid, taking out 50ml of the supernatant liquid 3 , enters the evaporation and concentration chamber for circulated spraying, combined with solar radiation heating, and uses the heat pump system to draw out hot air from the induced draft fan, providing a heat source for heating into the evaporation and concentration chamber, exchanging heat with the supernatant of the circulated sprayed ammonia vapor waste liquid to evaporate, generating high-humidity gas that is introduced into the refrigeration separation chamber, and then passes through the dehydration tank for gas-liquid separation to precipitate fresh water and then is led back to the cooling chamber; at the same time, the heat pump system draws out cold air from the induced draft fan, providing a cold source for cooling into the cooling chamber;

[0013] The air volume of the induced draft fan is 20000m 3 / h, the ammonia waste liquid evaporation equipment system has a circulation residence time of 5-9h, the ammonia waste liquid evaporation supernatant after evaporation, that is, the high-temperature liquid phase ammonia waste liquid supernatant after heat exchange is introduced into the heat exchanger, and is sprayed with the condensed and separated concentrated brine drawn out of the freezing separation chamber. The low-temperature liquid phase ammonia waste liquid supernatant cooled in the heat exchanger is led back to the cooling chamber;

[0014] In the cooling chamber, the cooling gas introduced by the heat pump system causes the supernatant of the low-temperature liquid phase of the ammonia vapor waste liquid to further exchange heat and cool down. After cooling, the liquid undergoes liquid-liquid heat exchange with concentrated brine. When the temperature drops to 20°C, it enters the freezing and separation chamber. The temperature of the freezing and separation chamber is -12 to -15°C, and the cycle freezing time is 12 hours. After the frozen ice cubes are promptly crushed and centrifuged, they are heated and heated with the high-humidity gas introduced by the evaporation and concentration chamber to obtain fresh brine. After passing through the freezing and separation chamber, the high-humidity gas enters the dehydration tank for gas-liquid separation. The separated liquid is collected and merged into fresh water, and the remaining high-humidity gas after cooling returns to the cooling chamber. A total of 22-26 tons of fresh water is obtained by drawing out the melted ice and condensed water from the freezing and separation chamber. The concentrated brine separated from the freezing and separation chamber is heated by heat exchange in the heat exchanger and enters the evaporation and crystallization chamber.

[0015] In the evaporation crystallization room, the concentrated brine is accelerated by combining sunlight heating and hot air heating introduced by the heat pump system. As the water in the concentrated brine evaporates, sodium chloride crystals will gradually precipitate and the dissolved density will gradually increase. When the density meter detects that the dissolved density reaches 1.36-1.40 g / cm 3The separated liquid is discharged into the cooling crystallization chamber, the temperature of the cooling crystallization chamber is controlled at 10°C, and 1-1.25t of anhydrous calcium chloride is added for stirring to obtain calcium chloride hexahydrate crystals; the concentrated liquid containing part of the calcium chloride hexahydrate is drawn out from the cooling crystallization chamber and is drawn back and mixed into the ammonia distillation waste liquid for recycling;

[0016] Finally, 1.75-2.4 tons of sodium chloride crystals and 10-11.65 tons of calcium chloride hexahydrate crystals are recovered, with a sodium chloride recovery rate of 75%, a calcium chloride recovery rate of 75%, and a water recovery rate of 59.7%.

[0017] In particular, the water temperature in the evaporation and concentration chamber should be controlled to be no less than 60°C.

[0018] In particular, the ammonia vapor waste liquid is first processed in a preliminary concentration chamber before being connected to the evaporation concentration chamber; wherein a centrifugal concentration device is provided in the preliminary concentration chamber.

[0019] In particular, the freezing separation chamber and the dehydration tank are connected to a fresh water collection system; the fresh water collection system obtains fresh water by distillation, reverse osmosis and electrodialysis.

[0020] Preferably, the cooling crystallization chamber adopts a heat pump system for cooling, or adopts partition heat exchange for cooling.

[0021] Preferably, the heat pump system includes a compressor, a heat exchanger, an axial flow fan, a water pump, an electronic expansion valve and an electronic automatic controller structure.

[0022] Preferably, the heat pump system includes an air source heat pump, a water source heat pump, a ground source heat pump, or a dual source heat pump combining a water source heat pump and an air source heat pump.

[0023] To achieve the above-mentioned purpose, the present invention also proposes a production equipment system for comprehensive treatment of waste ammonia liquid resource utilization, comprising: an evaporation and concentration chamber, a heat pump system, a cooling chamber, a freezing and separation chamber, a heat exchanger, an evaporation and crystallization chamber, and a cooling and crystallization chamber; the first heat pump system is connected to the evaporation and concentration chamber through a heating pipeline, the first heat pump system is connected to the cooling chamber through a cooling pipeline, the evaporation and concentration chamber is connected to the heat exchanger through a high-temperature liquid phase pipeline, the evaporation and concentration chamber is connected to the freezing and separation chamber through a high-humidity gas pipeline, the heat exchanger is connected to the cooling chamber through a low-temperature liquid phase pipeline, and the cooling chamber is connected in sequence. The freezing and separation chamber and the heat exchanger are connected. The freezing and separation chamber is directly connected to the fresh water pipeline or is connected to the fresh water pipeline through the dehydration tank. The dehydration tank is connected to the cooling chamber. The heat exchanger is further connected to the evaporation crystallization chamber and the cooling crystallization chamber in sequence. The second heat pump system is connected to the evaporation crystallization chamber through the heating pipeline. The second heat pump system is connected to the cooling crystallization chamber through the cooling pipeline. The evaporation crystallization chamber is connected to the sodium chloride crystallization outlet, the cooling crystallization chamber is connected to the anhydrous calcium chloride inlet, the cooling crystallization chamber is connected to the calcium chloride hexahydrate crystal outlet and the concentrated liquid outlet. The concentrated liquid outlet is circulated back to the evaporation and concentration chamber.

[0024] The top and sides of the evaporation and concentration chamber are composed of a concentrating glass sun room, which absorbs solar radiation during the day and increases the evaporation temperature of the ammonia waste liquid. A large number of spray pipes are installed in the area below 0.5m from the top of the evaporation and concentration chamber, and the spray pipes are evenly arranged. The newly introduced ammonia waste liquid and the recycled ammonia waste liquid in the evaporation and concentration chamber are mixed and then enter the spray pipes. The above-mentioned spray pipes are in the form of open-hole pipes with an aperture size of φ8 to 12mm, and the spacing between adjacent holes is no more than 20 to 60cm.

[0025] Furthermore, a refrigeration system is installed in the freezing separation chamber, including a compressor, a cold heat exchanger, a hot heat exchanger and an expansion valve.

[0026] An air inlet is provided at the middle and lower part of one side of the evaporation and concentration chamber, and an outlet is provided at the top of the side; a demister is provided at the outlet.

[0027] Preferably, at least two freezing crystallization chambers are provided and operate alternately.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) For ammonia distillation wastewater containing 4-6% sodium chloride, 10-15% calcium chloride, and 80-85% water, the process can achieve sodium chloride recovery rates of 75%, calcium chloride recovery rates of 75%, and water recovery rates of 55%. This reduces the input cost of raw salt in the alkali production process, while also reducing the amount of mixed solid slag landfilled and lowering operating costs.

[0030] 2) Relatively pure basic calcium chloride is recovered from the ammonia evaporation waste liquid, and subsequent refining can obtain basic calcium chloride products; at the same time, the obtained sodium chloride is refined and used as a raw material for the ammonia-soda plant.

[0031] 3) Depending on the object of use, the fresh water recovered from the ammonia evaporation waste liquid can be directly used as lime slurry, or it can be used as raw water for molten salt after treatment, reducing the use of raw water and saving water resources.

[0032] 4) Through the comprehensive utilization of ammonia waste liquid, the evaporation efficiency is accelerated, while the land area occupied by the evaporation of ammonia waste liquid in solar ponds is saved, thus realizing the comprehensive utilization of waste resources to a large extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way.

[0034] Figure 1 The figure is a schematic diagram of the process steps of the comprehensive utilization system of ammonia waste liquid evaporated by the ammonia-soda process of the present invention. DETAILED DESCRIPTION

[0035] The principle of the present invention is to set up a heat pump system, combine with sunlight radiation, and perform multi-stage heat exchange cycle treatment on ammonia waste liquid through evaporation, cooling and freezing separation, gas-liquid separation, evaporation crystallization and cooling crystallization. While recycling fresh water, sodium chloride and calcium chloride salts are effectively and continuously separated, which saves energy and reduces emissions, is safe and environmentally friendly. In addition, the technical measure of adding anhydrous calcium chloride to the final concentrated liquid is reasonably applied to promote the precipitation of calcium salts economically and efficiently.

[0036] In the present invention, the principle of the iron-carbon micro-electrolysis technology is that there is a potential difference between iron carbide and pure iron, which can form many tiny primary cells. In the primary cell, pure iron serves as the anode and iron carbide serves as the cathode. The products produced by the electrode reaction are highly active and can undergo redox reactions with the components in the wastewater, thereby degrading organic matter. At the same time, after the iron-carbon method undergoes micro-electrolysis, a large amount of Fe 3+ After aeration and oxidation, a large amount of Fe(OH)3 is produced. Fe(OH)2 has a strong flocculation ability and can effectively adsorb suspended matter in wastewater, thereby achieving the purpose of removing organic matter. This technology can promote the reduction and removal of various organic matter in the water that have inhibitory and toxic effects on microorganisms.

[0037] The present invention will be further described below with reference to the accompanying drawings and examples.

[0038] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

[0039] Example 1: Refer to the attached Figure 1 As shown, an equipment system for comprehensive utilization of ammonia waste liquid from ammonia-soda process, its comprehensive utilization treatment method and equipment system:

[0040] A. After the ammonia evaporation waste liquid is filtered to remove impurities, it enters the evaporation and concentration chamber: A1 The top and sides of the evaporation and concentration chamber are composed of a concentrating glass sun room, which absorbs solar radiation during the day and increases the evaporation temperature of the ammonia evaporation waste liquid; A2 A large number of spray pipes are installed in the area below 0.5m from the top of the evaporation and concentration chamber, and the spray pipes are evenly arranged; A3 The newly introduced ammonia evaporation waste liquid and the recycled ammonia evaporation waste liquid in the evaporation and concentration chamber are mixed and then enter the spray pipe; A4 The above-mentioned spray pipe is a perforated pipe with a hole size of 8 to 12mm and a spacing of no more than 20 to 60cm between adjacent holes. A5 The evaporation and concentration chamber is equipped with a heat exchanger to heat the liquid after spraying or to heat the inlet natural air; A6 The heat exchanger is a component of the heat pump system. The low-temperature and low-pressure gas in the heat pump system is compressed by the compressor and releases heat to heat the ammonia evaporation waste liquid in the evaporation and concentration chamber and is heated by the ammonia evaporation waste liquid. Heat is absorbed; an air inlet is provided at the lower middle portion of one side of the evaporation and concentration chamber described in A7, and an outlet is provided at the top of the side; a demister is provided at the outlet of A8, and the ammonia vapor waste liquid absorbs heat and is heated to form a high-temperature liquid phase ammonia vapor waste liquid, generating high-humidity gas; wherein, the high-temperature liquid phase ammonia vapor waste liquid enters the heat exchanger and undergoes liquid-liquid heat exchange with the low-temperature concentrated brine generated in the refrigeration separation chamber, after which the low-temperature liquid phase ammonia vapor waste liquid enters the cooling chamber; the high-humidity gas is drawn out from the outlet by an induced draft fan and enters the refrigeration separation chamber of the subsequent system; A9 controls the water temperature in the evaporation and concentration chamber to be no less than 60°C;

[0041] B. The high-humidity gas passes through the freezing separation chamber and the low-temperature gas after dehydration in the dehydration tank is introduced into the cooling chamber. Under the cooling supply of the heat pump system, it is mixed with the low-temperature liquid phase ammonia waste liquid to cool down together, and then enters the freezing separation chamber. After further cooling through gas heat exchange, it circulates for gas-liquid separation. The generated concentrated brine passes through the heat exchanger and undergoes liquid-liquid heat exchange with the high-temperature liquid phase ammonia waste liquid that has passed through the heat exchanger before entering the evaporation and crystallization chamber;

[0042] C. The high-temperature liquid-phase ammonia vapor waste liquid drawn out from the evaporation concentration chamber enters the freeze concentration system, and is cooled by the heat exchanger to form a low-temperature liquid-phase ammonia vapor waste liquid; the freeze concentration system includes a cooling chamber, a freezing separation chamber, a heat exchanger and a dehydration tank; C1 The cooling chamber is equipped with a cooling device of a heat pump system; C2 The circulating low-temperature liquid-phase ammonia vapor waste liquid cooled by the heat pump system and the dehydrated low-temperature and high-humidity gas entering the cooling chamber are used as a cold source to enter the freezing separation chamber; C3 Alternatively, a refrigeration system is installed in the freezing separation chamber, including a compressor, a cold heat exchanger, a hot heat exchanger, and an expansion valve; C4 The high-pressure low-temperature liquid in the internal coil of the compressor absorbs the temperature of the above-mentioned high-temperature liquid-phase ammonia vapor waste liquid entering the freezing system and gradually vaporizes into a low-temperature and low-pressure gas. Under the action of the compressor and the high-temperature liquid-phase ammonia vapor waste liquid, high-temperature and high-pressure gas and low-temperature and high-pressure liquid are gradually generated. In this process, the heat exchanger transfers the heat in the high-temperature liquid-phase ammonia vapor waste liquid into the concentrated brine liquid drawn out from the freeze concentration system that needs to be evaporated; the low-temperature liquid-phase ammonia vapor waste liquid crystallized in the freezing separation chamber is cooled. Temperature freezing, since the crystallization point of brine is lower than 0℃, after adding ice species, it is generally between -18 and 0℃. Therefore, at -18 to 0℃, the effluent in the brine is preferentially precipitated in the form of ice crystals, and the brine is concentrated. At least two freezing crystallization chambers are set in C4, which operate alternately. When concentrated to a certain concentration, centrifugal solid-liquid separation is performed to obtain freshwater ice and concentrated brine. The concentrated brine is heat-exchanged with the high-temperature liquid-phase ammonia evaporation waste liquid in step B to increase its temperature. At the same time, the high-temperature liquid-phase ammonia evaporation waste liquid in step B is cooled to a low-temperature liquid-phase ammonia evaporation waste liquid. The waste liquid is led back to the cooling chamber; C5 introduces the high-humidity gas generated by evaporation in the evaporation and concentration chamber into the freezing and separation chamber from which the concentrated brine has been discharged, performs gas-solid heat exchange, and condenses the high-humidity gas; C6 or, the condensed gas is further dehydrated in the dehydration tank and then enters the cooling chamber, and is finally emptied to further cool the high-temperature liquid phase ammonia vapor waste liquid in step B; C7 collects the dissolved liquid in the freezing and separation chamber and the condensate from the dehydration tank as fresh water; or, further processes it for molten brine or for lime pulping in the ammonia-soda process;

[0043] D. The concentrated brine, after being heated by the heat exchanger, enters the evaporation and crystallization chamber. The D1 evaporation and crystallization chamber uses a glass sunroom and a heat pump system for heat exchange and mechanical ventilation to accelerate the evaporation of water in the concentrated brine. The D2 concentrated brine pool is equipped with a liquid density meter to monitor the evaporation intensity of water to prevent the precipitation of calcium chloride in the evaporation and crystallization chamber. Only sodium chloride crystals are precipitated in the evaporation and crystallization chamber. D3 sodium chloride crystals are precipitated at the bottom of the evaporation and crystallization chamber and are regularly collected manually or mechanically. D4 collects the sodium chloride crystals and, after refining, is reused as raw material in the soda ash production process to save the use of raw materials.

[0044] E. After further evaporation to precipitate sodium chloride crystals, the concentrated brine containing calcium chloride enters the subsequent cooling crystallization chamber when the density reaches 1.36-1.40; the cooling crystallization chamber E1 uses a heat pump system for cooling, or adopts partition-type heat exchange for cooling; a certain amount of anhydrous calcium chloride solid is added to the remaining treated liquid of the concentrated brine after cooling in the cooling crystallization chamber E2 and stirred to promote supersaturation of calcium chloride to form calcium chloride hexahydrate crystals, and E3 performs solid-liquid separation on the concentrated brine containing calcium chloride hexahydrate crystals to obtain calcium chloride hexahydrate crystals. A small portion of the calcium chloride hexahydrate crystals is further dried and dehydrated to obtain anhydrous calcium chloride, which is returned to the cooling crystallization chamber for recycling. Most of the calcium chloride hexahydrate crystals are sold as raw materials to downstream companies to produce high-purity calcium chloride, thereby realizing resource recycling.

[0045] In this embodiment, the heat pump system is a highly efficient, energy-saving device that fully utilizes low-grade thermal energy. Heat can spontaneously transfer from a high-temperature object to a low-temperature object, but not spontaneously in the reverse direction. The heat pump system operates by forcing heat from a low-temperature object to a high-temperature object in a reverse cycle. This system consumes only a small amount of net reverse cycle work to produce a significant amount of heat, effectively utilizing otherwise difficult-to-use low-grade thermal energy and achieving energy savings. Heat pumps typically have a cooling coefficient of around 3-4, meaning they can transfer three to four times the energy they require from a low-temperature object to a high-temperature object. Therefore, a heat pump is essentially a heat-raising device. While operating, it consumes very little electrical energy itself, yet it can extract four to seven times that amount of energy from ambient media, such as water, air, and soil, to raise the temperature for utilization. This is the reason heat pumps are energy-efficient. A ground-source heat pump is a type of heat pump that uses the earth or water as a heat or cold source to provide air conditioning for buildings, providing warmth in winter and cooling in summer. A ground-source heat pump simply "transfers" energy between the earth and the interior. Use minimal electricity to maintain the required indoor temperature.

[0046] Since the working principle of a heat pump is the same as that of compression refrigeration, in a small air conditioner, in order to fully utilize its efficiency, the same equipment can be used for both summer cooling and winter heating. During winter heating, the evaporator and condenser in the air conditioner are switched via a reversing valve. During summer cooling, the air conditioner operates according to the cooling mode. The high-pressure steam discharged from the compressor enters the condenser through a reversing valve or a four-way valve. The refrigerant vapor is condensed into liquid and then enters the evaporator through a throttling device. There, it absorbs heat and cools the indoor air. The evaporated refrigerant vapor passes through the reversing valve and is sucked into the compressor. This cycle repeats itself, completing the refrigeration cycle. During winter heating, the reversing valve is first turned to the heat pump operating position. High-pressure refrigerant vapor discharged from the compressor flows through the reversing valve into the indoor evaporator, serving as the condenser. The latent heat released during condensation heats the indoor air, achieving indoor heating. The condensed liquid refrigerant then flows in the opposite direction, through the throttling device, into the condenser, serving as the evaporator, absorbing heat from the outside air and evaporating. The evaporated vapor then passes through the reversing valve and is drawn into the compressor, completing the heating cycle. This process "pumps" heat from the outside air or circulating water into the warmer indoor temperature, hence the name "heat pump." In a split-type heat pump air conditioner, during summer cooling, the outdoor unit acts as the condenser and the indoor unit as the evaporator, transferring indoor heat to the outdoors. In winter, the indoor unit acts as the condenser and the outdoor unit as the evaporator, transferring outdoor heat to the indoors. This is typically accomplished through a four-way reversing valve, which is found in heat pump air conditioners. During cooling operation, the indoor heat exchanger serves as the evaporator, and the outdoor heat exchanger serves as the condenser. During winter heating, the four-way reversing valve switches, changing the refrigerant flow direction. At this point, the indoor heat exchanger acts as the condenser, and the outdoor heat exchanger acts as the evaporator. Because cold air blows out in winter, the heat exchanger will frost. When frost reaches a certain level, the four-way reversing valve switches again, switching the air conditioner to summer cooling mode. Heat is then transferred to the outdoor heat exchanger, defrosting the air. Once defrosting is complete, the four-way valve switches back to heating mode. During defrosting, the indoor unit's fan stops to prevent cold air from blowing into the room.

[0047] A heat pump system includes a compressor, heat exchanger, axial fan, water pump, electronic expansion valve, and electronic automatic controller. Heat pump systems include air-source heat pumps, water-source heat pumps, ground-source heat pumps, and dual-source heat pumps that combine water-source and air-source heat pumps.

[0048] For example, an air source heat pump water heater is mainly composed of a compressor, a heat exchanger, an axial flow fan, an insulated water tank, a water pump, a liquid storage tank, a filter, an electronic expansion valve and an electronic automatic controller. After the power is turned on, the axial flow fan starts to run, and the outdoor air passes through the evaporator for heat exchange. The air with a lowered temperature is discharged from the system by the fan. At the same time, the working fluid inside the evaporator absorbs heat and vaporizes and is sucked into the compressor. The compressor compresses this low-pressure working fluid gas into a high-temperature, high-pressure gas and sends it to the condenser. The water forced to circulate by the water pump also passes through the condenser, is heated by the working fluid and sent to the user for use, while the working fluid is cooled into a liquid. After being throttled and cooled by the expansion valve, the liquid flows into the evaporator again. This cycle is repeated, and the heat energy in the air is continuously "pumped" into the water, causing the water temperature in the insulated water tank to gradually increase, finally reaching about 55°C, which is just right for people to bathe.

[0049] Example 2: A comprehensive utilization and treatment method for ammonia evaporation waste liquid from an ammonia-soda process, treating the ammonia evaporation waste liquid and recovering sodium chloride, calcium chloride, and water. The components of the ammonia evaporation waste liquid used are as follows:

[0050]

[0051] The treatment process includes: filtering the ammonia waste liquid to obtain a clear liquid, taking out 50ml of the supernatant liquid 3 , enters the evaporation and concentration chamber for circulated spraying, combined with solar radiation heating, and uses the heat pump system to draw out hot air from the induced draft fan, providing a heat source for heating into the evaporation and concentration chamber, exchanging heat with the supernatant of the circulated sprayed ammonia vapor waste liquid to evaporate, generating high-humidity gas that is introduced into the refrigeration separation chamber, and then passes through the dehydration tank for gas-liquid separation to precipitate fresh water and then is led back to the cooling chamber; at the same time, the heat pump system draws out cold air from the induced draft fan, providing a cold source for cooling into the cooling chamber;

[0052] The air volume of the induced draft fan is 20000m 3 / h, the circulation residence time of the ammonia evaporation waste liquid equipment system is 8h, the supernatant of the ammonia evaporation waste liquid after evaporation, that is, the high-temperature liquid phase of the ammonia evaporation waste liquid supernatant after heat exchange is introduced into the heat exchanger, and is heat-exchanged with the condensed and separated concentrated brine drawn out of the freezing separation chamber through spraying, and the low-temperature liquid phase of the ammonia evaporation waste liquid supernatant cooled after heat exchange in the heat exchanger is led back to the cooling chamber;

[0053] In the cooling chamber, the cooling gas introduced by the heat pump system causes the supernatant of the low-temperature liquid phase of the ammonia vapor waste liquid to further exchange heat and cool down. After cooling, the liquid undergoes liquid-liquid heat exchange with concentrated brine. When the temperature drops to 20°C, it enters the freezing separation chamber. The temperature of the freezing separation chamber is -12°C, and the cycle freezing time is 12 hours. After the frozen ice cubes are promptly crushed and centrifuged, they are heated by heat exchange with the high-humidity gas introduced by the evaporation and concentration chamber to obtain brine. After passing through the freezing separation chamber, the high-humidity gas enters the dehydration tank for gas-liquid separation. The separated liquid is collected and merged into fresh water. The remaining high-humidity gas after cooling returns to the cooling chamber. A total of 23 tons of fresh water is obtained by extracting the melted ice and condensed water from the freezing separation chamber. The concentrated brine separated from the freezing separation chamber is heated by heat exchange in the heat exchanger and enters the evaporation and crystallization chamber.

[0054] In the evaporation crystallization room, the concentrated brine is accelerated by combining sunlight heating and hot air heating introduced by the heat pump system. As the water in the concentrated brine evaporates, sodium chloride crystals will gradually precipitate and the dissolved density will gradually increase. When the density meter detects that the dissolved density reaches 1.35g / cm 3 The separated liquid is discharged into the cooling crystallization chamber, the temperature of the cooling crystallization chamber is controlled at 10°C, and 1.1t of anhydrous calcium chloride is added for stirring to obtain calcium chloride hexahydrate crystals; the concentrated liquid containing part of the calcium chloride hexahydrate is drawn out from the cooling crystallization chamber and is drawn back and mixed into the ammonia distillation waste liquid for recycling;

[0055] Finally, 1.95 tons of sodium chloride crystals and 10.29 tons of calcium chloride hexahydrate crystals were recovered, with a sodium chloride recovery rate of 75%, a calcium chloride recovery rate of 75%, and a water recovery rate of 59.7%.

[0056] Example 3: A comprehensive utilization and treatment method for ammonia evaporation waste liquid from an ammonia-soda process, treating the ammonia evaporation waste liquid and recovering sodium chloride, calcium chloride and water. The components of the ammonia evaporation waste liquid used are as follows:

[0057]

[0058] The treatment process includes: filtering the ammonia waste liquid to obtain a clear liquid, taking out 50ml of the supernatant liquid 3 , enters the evaporation and concentration chamber for circulated spraying, combined with solar radiation heating, and uses the heat pump system to draw out hot air from the induced draft fan, providing a heat source for heating into the evaporation and concentration chamber, exchanging heat with the supernatant of the circulated sprayed ammonia vapor waste liquid to evaporate, generating high-humidity gas that is introduced into the refrigeration separation chamber, and then passes through the dehydration tank for gas-liquid separation to precipitate fresh water and then is led back to the cooling chamber; at the same time, the heat pump system draws out cold air from the induced draft fan, providing a cold source for cooling into the cooling chamber;

[0059] The air volume of the induced draft fan is 20000m 3 / h, the ammonia waste liquid evaporation equipment system has a circulation residence time of 6h, the ammonia waste liquid evaporation supernatant after evaporation, that is, the high-temperature liquid phase ammonia waste liquid supernatant after heat exchange is introduced into the heat exchanger, and is sprayed with the condensed and separated concentrated brine drawn out of the freezing separation chamber. The low-temperature liquid phase ammonia waste liquid supernatant cooled in the heat exchanger is led back to the cooling chamber;

[0060] In the cooling chamber, the cooling gas introduced by the heat pump system causes the supernatant of the low-temperature liquid phase of the ammonia vapor waste liquid to further exchange heat and cool down. After cooling, the liquid undergoes liquid-liquid heat exchange with concentrated brine. When the temperature drops to 20°C, it enters the freezing separation chamber. The temperature of the freezing separation chamber is -15°C, and the cycle freezing time is 12 hours. After the frozen ice cubes are promptly crushed and centrifuged, they are heated by heat exchange with the high-humidity gas introduced by the evaporation and concentration chamber to obtain fresh brine. After passing through the freezing separation chamber, the high-humidity gas enters the dehydration tank for gas-liquid separation. The separated liquid is collected and merged into fresh water, and the remaining high-humidity gas after cooling returns to the cooling chamber. A total of 25 tons of fresh water is obtained by extracting the melted ice and condensed water from the freezing separation chamber. The concentrated brine separated from the freezing separation chamber is heated by heat exchange in the heat exchanger and enters the evaporation and crystallization chamber.

[0061] In the evaporation crystallization chamber, the concentrated brine is accelerated by combining sunlight heating and hot air heating introduced by the heat pump system. As the water in the concentrated brine evaporates, sodium chloride crystals will gradually precipitate and the dissolved density will gradually increase. When the density meter detects that the dissolved density reaches 1.42g / cm 3 The separated liquid is discharged into the cooling crystallization chamber, the temperature of the cooling crystallization chamber is controlled at 10°C, and 1.2t of anhydrous calcium chloride is added for stirring to obtain calcium chloride hexahydrate crystals; the concentrated liquid containing part of calcium chloride hexahydrate is drawn out from the cooling crystallization chamber and is drawn back and mixed into the ammonia distillation waste liquid for recycling;

[0062] Finally, 2.2 tons of sodium chloride crystals and 11.23 tons of calcium chloride hexahydrate crystals were recovered, with a sodium chloride recovery rate of 87%, a calcium chloride recovery rate of 78.6%, and a water recovery rate of 59.9%.

[0063] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on this application. In this application, unless otherwise expressly specified and limited, terms such as "installed", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection.

[0064] The above embodiments further illustrate the technical solutions in detail, but it should not be mistakenly assumed that the present invention is limited thereto. Within the technical field to which the present invention pertains, a person of ordinary skill in the art may easily come up with several simple deductions or replacement technical solutions without departing from the overall concept of the present invention and without inventive work, and such alternatives should be deemed to fall within the scope of protection defined by the claims submitted by the present invention.

Claims

1. A comprehensive utilization and treatment method for ammonia-soda process ammonia distillation wastewater, characterized in that: A heat pump system, combined with solar radiation, processes the ammonia wastewater through a multi-stage heat exchange cycle, including evaporation, cooling and freezing separation, gas-liquid separation, evaporation crystallization, and cooling crystallization. This effectively and continuously separates sodium chloride and calcium chloride salts while recycling fresh water. The ammonia wastewater used contains the following components: CaCl2 8-13%, NaCl 4-7%, H2O 75-95%, CaSO4 0.045-0.06%, and Ca(OH)2 0.035-0.055%. The treatment process includes: filtering the ammonia waste liquid to obtain a clear liquid, taking out 50ml of the supernatant liquid 3 , enter the evaporation and concentration room for circulatory spraying, combined with solar radiation heating, and use the heat pump system to draw out hot air from the induced draft fan, providing a heat source for heating into the evaporation and concentration room, exchanging heat with the supernatant of the circulatory sprayed ammonia waste liquid to evaporate, generating high-humidity gas that is introduced into the refrigeration separation room, and then passes through the dehydration tank for gas-liquid separation to precipitate fresh water and then lead back to the cooling room, controlling the water temperature in the evaporation and concentration room to be no lower than 60℃; at the same time, the heat pump system draws out cold air from the induced draft fan, providing a cold source for cooling into the cooling room; The air volume of the induced draft fan is 20000m 3 / h, the ammonia waste liquid evaporation equipment system has a circulation residence time of 5-9h, the ammonia waste liquid evaporation supernatant after evaporation, that is, the high-temperature liquid phase ammonia waste liquid supernatant after heat exchange is introduced into the heat exchanger, and is sprayed with the condensed and separated concentrated brine drawn out of the freezing separation chamber. The low-temperature liquid phase ammonia waste liquid supernatant cooled in the heat exchanger is led back to the cooling chamber; In the cooling chamber, the cooling gas introduced by the heat pump system causes the supernatant of the low-temperature liquid phase of the ammonia vapor waste liquid to further exchange heat and cool down. After cooling, the liquid undergoes liquid-liquid heat exchange with concentrated brine. When the temperature drops to 20°C, it enters the freezing and separation chamber. The temperature of the freezing and separation chamber is -12 to -15°C, and the cycle freezing time is 12 hours. After the frozen ice cubes are promptly crushed and centrifuged, they are heated and heated with the high-humidity gas introduced by the evaporation and concentration chamber to obtain fresh brine. After passing through the freezing and separation chamber, the high-humidity gas enters the dehydration tank for gas-liquid separation. The separated liquid is collected and merged into fresh water, and the remaining high-humidity gas after cooling returns to the cooling chamber. A total of 22-26 tons of fresh water is obtained by drawing out the melted ice and condensed water from the freezing and separation chamber. The concentrated brine separated from the freezing and separation chamber is heated by heat exchange in the heat exchanger and enters the evaporation and crystallization chamber. In the evaporation crystallization room, the concentrated brine is accelerated by combining sunlight heating and hot air heating introduced by the heat pump system. As the water in the concentrated brine evaporates, sodium chloride crystals will gradually precipitate and the dissolved density will gradually increase. When the density meter detects that the dissolved density reaches 1.36-1.40 g / cm 3 The separated liquid is discharged into the cooling crystallization chamber, the temperature of the cooling crystallization chamber is controlled at 10°C, and 1-1.25t of anhydrous calcium chloride is added for stirring to obtain calcium chloride hexahydrate crystals; the concentrated liquid containing part of calcium chloride hexahydrate is drawn out from the cooling crystallization chamber and is drawn back and mixed into the ammonia distillation waste liquid for recycling.

2. The comprehensive utilization and treatment method of ammonia-soda process ammonia distillation waste liquid according to claim 1, characterized in that: Before being connected to the evaporation and concentration chamber, the ammonia waste liquid is first processed in the preliminary concentration chamber; wherein, a centrifugal concentration equipment is installed in the preliminary concentration chamber.

3. The comprehensive utilization and treatment method of ammonia-soda process ammonia distillation waste liquid according to claim 1, characterized in that: The freezing separation chamber and the dehydration tank are connected to a fresh water collection system; the fresh water collection system obtains fresh water by using distillation, reverse osmosis and electrodialysis.

4. The comprehensive utilization and treatment method of ammonia-soda process ammonia distillation wastewater according to claim 1, characterized in that: The cooling crystallization chamber adopts a heat pump system for cooling, or adopts a partition-type heat exchange for cooling.

5. The comprehensive utilization and treatment method of ammonia-soda process ammonia distillation wastewater according to claim 1, characterized in that: The heat pump system includes a compressor, a heat exchanger, an axial flow fan, a water pump, an electronic expansion valve and an electronic automatic controller structure; the heat pump system includes an air source heat pump, a water source heat pump, a ground source heat pump, and a dual-source heat pump combining a water source heat pump and an air source heat pump.

6. An equipment system using the comprehensive utilization and treatment method of ammonia-soda process ammonia distillation wastewater according to claim 1, comprising: Evaporation and concentration chamber, heat pump system, cooling chamber, freezing and separation chamber, heat exchanger, evaporation and crystallization chamber and cooling and crystallization chamber; characterized in that the first heat pump system is connected to the evaporation and concentration chamber through a heating pipeline, the first heat pump system is connected to the cooling chamber through a cooling pipeline, the evaporation and concentration chamber is connected to the heat exchanger through a high-temperature liquid phase pipeline, the evaporation and concentration chamber is connected to the freezing and separation chamber through a high-humidity gas pipeline, the heat exchanger is connected to the cooling chamber through a low-temperature liquid phase pipeline, the cooling chamber is connected to the freezing and separation chamber and the heat exchanger in sequence, the freezing and separation chamber is directly connected to the fresh water pipeline or is connected to the fresh water pipeline through a dehydration tank, the dehydration tank is connected to the cooling chamber, the heat exchanger is further connected to the evaporation and crystallization chamber and the cooling and crystallization chamber in sequence, the second heat pump system is connected to the evaporation and crystallization chamber through a heating pipeline, the second heat pump system is connected to the cooling and crystallization chamber through a cooling pipeline, the evaporation and crystallization chamber is connected to a sodium chloride crystal outlet, the cooling and crystallization chamber is connected to an anhydrous calcium chloride inlet, the cooling and crystallization chamber is connected to a calcium chloride hexahydrate crystal outlet and a concentrated liquid outlet, and the concentrated liquid outlet is circulated back to the evaporation and concentration chamber.

7. The equipment system for the comprehensive utilization and treatment method of ammonia-soda process ammonia distillation waste liquid according to claim 6, characterized in that: The top and surrounding areas of the evaporation and concentration chamber are composed of a concentrating glass sunroom, which absorbs solar radiation during the day and increases the evaporation temperature of the ammonia waste liquid. A large number of spray pipes are installed in the area below 0.5m from the top of the evaporation and concentration chamber, and the spray pipes are evenly arranged. The newly introduced ammonia waste liquid and the recycled ammonia waste liquid in the evaporation and concentration chamber are mixed and then enter the spray pipes. The above-mentioned spray pipes are in the form of open-hole pipes with an aperture size of φ8 to 12mm, and the spacing between adjacent holes is no more than 20 to 60cm.

8. The equipment system for the comprehensive utilization and treatment method of ammonia-soda process ammonia distillation waste liquid according to claim 6, characterized in that: A refrigeration system is installed in the refrigeration separation chamber, including a compressor, a cold heat exchanger, a hot heat exchanger and an expansion valve.

9. The equipment system for the comprehensive utilization and treatment method of ammonia-soda process ammonia distillation waste liquid according to claim 6, characterized in that: An air inlet is provided at the middle and lower part of one side of the evaporation and concentration chamber, and an outlet is provided at the top of the side; a demister is provided at the outlet.

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