High-efficient energy-saving manufacturing waste heat recovery and utilization system, process of the same, and silica gel mass-production method

Abstract

To provide a highly efficient energy-saving manufacturing waste heat recovery and utilization system.SOLUTION: The system includes a moisture waste heat recovery module for recovering and utilizing thermal energy of thermal moisture generated in a process of drying a substance. The moisture waste heat recovery module includes a conveyor for mounting a substance, a dryer, a compressor, and / or a heat exchanger, the conveyor passes through a plurality of dryers successively, the dryer is connected to the compressor and / or the heat exchanger through piping, and the thermal moisture generated in the compressor and / or the heat exchanger is recycled to dry the substance. The present invention also provides a method for mass-producing silica gel. In the method for mass-producing silica gel according to the present invention, the process of producing silica gel forms an environment-friendly circulation, no waste water, waste air and solid waste are discharged, the circulation of sulfur element, sodium element, and silicon element is realized, and the circulation of water resources and heat resources is also realized, the high-efficient energy saving is realized, and it is suitable for industrial mass-production.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of manufacturing silica gel, and particularly to a high-efficiency energy-saving manufacturing waste heat recovery and utilization system and its process, as well as a method for mass-producing silica gel.

Background Art

[0002] Silica gel is silica xerogel having a three-dimensional network structure, a porous substance with a wide pore distribution range and a large specific surface area, covered with a large number of silanol groups on the surface, and having a certain activity. Due to such characteristics, silica gel plays an important role as a desiccant, adsorbent, catalyst, catalyst carrier, etc., and is widely used in industrial manufacturing fields such as medical, electronics, cosmetics, and food processing.

[0003] In the manufacturing process of silica gel, sodium silicate and sulfuric acid are used as main raw materials, silica gel is generated by the sol-gel method, and then, through aging, cutting, washing with water, and drying, a finished silica gel product is obtained. Throughout the manufacturing process, the manufactured products include, in addition to the finished silica gel, scraps of wet silica gel, scraps of dry silica gel, sodium sulfate brine, and waste water. Currently, as methods for disposing of scraps of wet silica gel and scraps of dry silica gel, they are either treated as scrap or sold at a low price. Sodium sulfate brine has a relatively high recovery cost due to reasons such as concentration and treatment cost, and the value of the recovered product is not high, so it is inevitably discharged to a sewage treatment plant as waste water for treatment. Waste water such as the water for washing with water and condensed water generated is also directly discharged to a sewage treatment plant as sewage for treatment. Chinese Patent No. 201210121870.5 discloses a method for preparing silica gel, which is a method of reacting with NaHCO 3 or NH 4 HCO 3 as a raw material with sodium silicate Na 2 O·nSiO 2 to generate SiO 2 hydrogel, and obtaining silica gel through forming, aging, and drying processes. In this method, the recovered washing liquid (or filtrate, etc.) is mainly Na 2 CO3 contains (or NH 3 ·H 2 O also contains), so the reaction raw materials can be reacquired by introducing CO 2 and reacting it. Therefore, except for the silicon source, all other chemical substances can be recycled. Compared with the prior art, the raw material cost of silica gel can be reduced to a certain extent, and the problems of generating wastewater containing acids and salts and environmental pollution can be solved. However, the technical solution of this patent is only theoretically feasible. On the one hand, because carbon dioxide is added to the wastewater, the cost is very high. On the other hand, in the technology of this patent, the consumption of raw materials and the yield of products remain at the laboratory stage. Due to the poor weak acid reaction effect, the mass production needs of silica gel cannot be met.

[0004] Sodium silicate is solid sodium silicate, and its molecular formula is Na 2 O·nSiO 2 where n is the modulus of elasticity, and SiO 2 and Na 2 O refers to the molar ratio, generally 1.5 - 3.5. The larger the modulus of elasticity of solid sodium silicate, the more difficult it is to dissolve in water. When n = 1, it can dissolve in normal temperature water, but when n increases, hot water is required for dissolution. When n > 3, steam exceeding 4 atmospheres is required for dissolution. The larger the modulus of elasticity of sodium silicate, the higher the silicon dioxide content, the higher the viscosity of sodium silicate, the easier it is to decompose and harden, and the greater the binding force. Sodium silicate is the product at the most upstream of the industrial chain and is often used as a basic chemical raw material for manufacturing other downstream products and is also an important raw material for manufacturing silica gel.

[0005] The production of sodium silicate includes dry production and wet production. Dry production methods include the soda ash method and the sodium sulfate method. Among these, the soda ash method involves mixing quartz sand and soda ash at a certain ratio and heating them to about 1400 °C in a reverberatory furnace to produce molten sodium silicate. The wet production method includes the caustic soda method, which uses quartz sand (powder) and caustic soda as raw materials and reacts them with steam at 0.6 - 1.0 MPa in an autoclave to directly produce liquid sodium silicate. Among the above production methods, in the prior art, the soda ash method is common. However, this soda ash method emits more than 137 kilograms of CO 2 per ton of product, which has an adverse impact on the ecological environment. In the production of sodium silicate, the sodium sulfate method is preferred by enterprises because its cost is lower compared to the soda ash method and the caustic soda method. However, this method also has the following problems. First, environmental pollution is severe, and existing desulfurization treatments have little effect. For example, when anhydrous sodium sulfate is used in the production of sodium silicate, sodium sulfate undergoes a chemical reaction with quartz sand during the production process, generating a large amount of sulfur dioxide gas. In this method, a large amount of SO 2 is generated during the production process, and more than 200 kilograms of SO 2 is discharged per ton of product, which is 130 times the discharge amount of the soda ash method, leading to serious environmental pollution. In the prior art, attempts have been made to use desulfurization treatments such as the alkali absorption method, the catalyst method, and the ammonia water absorption method, but the desulfurization efficiency is not high, the economic investment and results are disproportionate, and the concentration of sulfur dioxide after treatment deviates greatly from the emission standards. Even if it is neutralized and discharged as sulfate or sulfite, it results in a waste of resources. Second, inside the reverberatory furnace equipment for the reaction, due to the severe acidic atmosphere, the corrosion of refractory bricks is intense, and the service life of the furnace is only 4 - 6 months. Also, due to the constraints of environmental protection regulations, the technological development of the sodium sulfate method is restricted, and the technology for producing sodium silicate by the sodium sulfate method has become a manufacturing technology abandoned in the existing technology.

[0006] In the conventional sulfuric acid manufacturing process, sulfur or pyrite is burned in an incinerator into which oxygen-enriched air is introduced. After the gas containing the generated sulfur dioxide is dust-removed, an appropriate amount of air is added and then it flows into a converter. The sulfur dioxide is converted into sulfur trioxide with a vanadium catalyst, and finally, sulfuric acid is produced by absorption with dilute sulfuric acid. However, the oxygen-enriched air required in the manufacturing process is supplied by an air separation device. Chinese Patent No. CN202010888165.2 discloses a method and apparatus for manufacturing sodium silicate and sulfuric acid from high-sulfur-content salts, in which sulfur-containing industrial salt and silicon dioxide are burned with all oxygen to produce sodium silicate. The sulfur-containing flue gas generated during the manufacturing process undergoes heat exchange, dust removal, conversion, and absorption to produce sulfuric acid. However, in the manufacturing scenario according to the technical solution of this patent, in order to achieve continuous and steady production of acid, it is necessary to use oxygen-enriched air supplied from an air separation device. Such a design increases the manufacturing input cost...

[0007] Furthermore, the waste heat generated during the production of sodium silicate and the waste heat during the production of silica gel are very valuable heat resources, and there is no waste heat recovery system specialized for the production of sodium silicate or silica gel in the prior art. Therefore, the prior art needs to be solved urgently.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The object of the present invention is to provide a high-efficiency energy-saving manufacturing waste heat recovery and utilization system and its process, as well as a method for mass-producing silica gel, in view of the drawbacks of the prior art. Based on the above problems, in the high-efficiency energy-saving manufacturing waste heat recovery and utilization system and its process, and the method for mass-producing silica gel proposed in the present invention, the process of manufacturing silica gel forms an environmentally friendly cycle, with no emissions of waste gas, waste water, and solid waste, realizing the circulation of sulfur, sodium, and silicon elements, and also realizing the circulation of water resources and heat resources, achieving high efficiency and energy saving, and being suitable for industrial mass production.

Means for Solving the Problems

[0009] The technical solution of the present invention is achieved as follows.

[0010] A high-efficiency energy-saving manufacturing waste heat recovery and utilization system, including a moisture waste heat recovery module that recovers and utilizes the thermal energy of the hot and humid air generated in the process of drying substances, the moisture waste heat recovery module includes a conveyor for placing substances, a dryer, a compressor and / or a heat exchanger, the conveyor sequentially passes through a plurality of dryers, the dryers are respectively connected to the compressor and / or the heat exchanger through pipelines, and the hot and humid air generated by the compressor and / or the heat exchanger is recycled for drying substances.

[0011] In the above high-efficiency energy-saving manufacturing waste heat recovery and utilization system, the moisture waste heat recovery module specifically includes a preheating conveyor, a first dryer, a second dryer, a third dryer, a first compressor, and a first heat exchanger, the preheating conveyor sequentially passes through the first dryer, the second dryer, and the third dryer, the preheating conveyor, the first dryer, and the second dryer are respectively connected to the first compressor through pipelines, and the second dryer and the third dryer are respectively connected to the first heat exchanger through pipelines.

[0012] In the above high-efficiency energy-saving manufacturing waste heat recovery and utilization system, it further includes a flue gas waste heat recovery module that recovers and utilizes the thermal energy of the high-temperature flue gas generated in the manufacturing process, the flue gas waste heat recovery module includes a waste heat boiler, a second heat exchanger, and a first heat pump, the inlet end of the waste heat boiler is connected to a reverberatory furnace and a sulfur combustion furnace that generate high-temperature flue gas, the outlet end of the waste heat boiler is connected to the medium-temperature flue gas inlet end of the second heat exchanger, the high-temperature air outlet end of the second heat exchanger is respectively connected to the reverberatory furnace and the sulfur combustion furnace, the flue gas outlet end of the second heat exchanger is connected to the first heat pump, the first heat pump is connected to the external normal-temperature air and tap water, and the medium-temperature air outlet end of the first heat pump is connected to the second heat exchanger.

[0013] In the above high-efficiency energy-saving manufacturing waste heat recovery and utilization system, it further includes a first waste water waste heat recovery module for recovering and utilizing the thermal energy generated in the process of preparing raw materials. The first waste water waste heat recovery module includes a cooler, and the tap water or the waste water from the salt recovery treatment device flows through the cooler to be heated up and then flows to the water washing device.

[0014] In the above high-efficiency energy-saving manufacturing waste heat recovery and utilization system, it further includes a second waste water waste heat recovery module for recovering and utilizing the thermal energy generated in the process of recovering and treating salt. The second waste water waste heat recovery module includes a second heat pump and a mixing heater. The second heat pump is connected to the water washing device through a pipeline, and the water washing device is connected to the mixing heater through a pipeline.

[0015] In the above high-efficiency energy-saving manufacturing waste heat recovery and utilization system, it further includes a third waste water waste heat recovery module for recovering and utilizing the thermal energy generated in the process of drying silica gel.

[0016] Based on the same technical concept, the present invention provides a high-efficiency energy-saving manufacturing waste heat recovery and utilization process, which uses the above manufacturing waste heat recovery and utilization system to recover and utilize thermal energy. The manufacturing waste heat recovery and utilization process includes: Placing wet substances on a conveyor, sequentially passing the conveyor through a plurality of dryers for transportation, and drying the substances by the plurality of dryers to obtain dry substances, including a heat recovery and utilization process of hot and humid air. The conveyor and the dryer are respectively connected to a compressor and / or a heat exchanger through pipelines, and the hot and humid air generated by the compressor and / or the heat exchanger is recycled for drying the substances.

[0017] Furthermore, it further includes a process for heat recovery and utilization of flue gas. In this process for heat recovery and utilization of flue gas, the high-temperature flue gas generated by the reverberatory furnace and the sulfur combustion furnace is introduced into a waste heat boiler. The waste heat boiler recovers the thermal energy of the high-temperature flue gas, and the generated medium-temperature flue gas is introduced into a second heat exchanger for heat exchange. A first heat pump recovers the thermal energy of the flue gas discharged from the second heat exchanger. A part of it is used to heat tap water for use in the water washing process, and another part is used to heat normal-temperature air to medium-temperature air. The medium-temperature air is introduced into the second heat exchanger for heat exchange with the medium-temperature flue gas. On one hand, low-temperature flue gas is generated and introduced into the first heat pump to become even lower-temperature flue gas after further temperature reduction. On the other hand, high-temperature air is generated and used for the combustion support of the reverberatory furnace and the sulfur combustion furnace.

[0018] Furthermore, it further includes a process for heat recovery and utilization of the first wastewater, in which the thermal energy from the dilution of concentrated sulfuric acid and the melting of sodium silicate is recovered by a cooler to heat tap water and frozen crystallization water for use in the water washing process.

[0019] Furthermore, it further includes a process for heat recovery and utilization of the second wastewater, in which the sodium sulfate brine generated in the water washing process is introduced into a second heat pump, and the second heat pump further recovers the thermal energy of the wastewater discharged in the water washing process.

[0020] Furthermore, it further includes a process for heat recovery and utilization of the third wastewater, in which the condensed water generated by the first dryer and the second dryer is collected and used for the water washing process or heating.

[0021] Based on the same technical concept, the present invention provides a method for mass-producing silica gel, which includes using the above high-efficiency energy-saving manufacturing waste heat recovery and utilization process. The method for mass-producing silica gel includes: Step S1 of reacting a silicon source, a sodium salt, and a sulfur-containing fuel at a specific reaction temperature in a predetermined ratio to generate sodium silicate and generate flue gas rich in sulfur dioxide; Add sulfur, supplement an appropriate amount of air for combustion, adjust the sulfur dioxide in the flue gas to a certain concentration, then enter the acid washing and purification section, purify, dry, let it flow into the converter, convert it into sulfur trioxide by catalytic conversion, and finally absorb it with concentrated sulfuric acid to obtain industrial sulfuric acid in step S2, Prepare a solution using the sodium silicate produced in step S1 and the sulfuric acid obtained in step S2, gel it, age it, cut it, wash it with water, and dry it to produce dry silica gel. In the process of drying the silica gel, use the above-mentioned waste heat recovery and utilization system to recover and utilize the thermal energy of the hot and humid air, and recycle it for the drying of substances in step S3. Further, in the water washing process, use the above-mentioned waste heat recovery and utilization system to recover and utilize the thermal energy of the flue gas, recycle it for heating the water for washing, the heated water becomes steam and is reused, and the heated air is used for assisting combustion in the reverberatory furnace and the sulfur combustion furnace. Further, in the water washing process, use the above-mentioned waste heat recovery and utilization system to recover and utilize the heat of the first wastewater and recycle the thermal energy for heating the water for washing. Further, in the water washing process, use the above-mentioned waste heat recovery and utilization system to recover and utilize the heat of the second wastewater and recycle the thermal energy for heating the water for washing or use it for heating the heating water. Further, in the water washing process, use the above-mentioned waste heat recovery and utilization system to recover and utilize the heat of the third wastewater and recycle the thermal energy for heating the water for washing or use it for heating the heating water.

[0022] In the above silica gel mass production method, the silicon source in the step S1 is any one selected from (a1) quartz sand, (a2) the scraps of dry silica gel produced in the step of manufacturing dry silica gel, (a3) the scraps of wet silica gel produced in the steps of aging and cutting, (a4) the alkaline mud precipitated by filtration during the solution preparation with sodium silicate, and (a5) polysilicon slag.

[0023] In the above-described method for mass-producing silica gel, the sodium salt in the S1 step is any one selected from (b1) sodium sulfate decahydrate after desalting the sodium sulfate brine generated in the water washing step, (b2) anhydrous sodium sulfate after desalting the sodium sulfate brine generated in the water washing step, (b3) sodium salts of sulfur-containing solid waste such as sodium thiosulfate, sodium thiocyanate, and sodium sulfite, and (b4) any one selected from the quenching liquids generated in the quenching tank in the process of manufacturing sodium silicate.

[0024] In the above-described method for mass-producing silica gel, in the water washing step in the S3 step, the water used in the water washing step is any one or more selected from (c1) wastewater generated in the treated water washing step, (c2) water condensed from the water vapor generated in the silica gel drying step, (c3) condensed water generated in the sulfur combustion furnace and waste heat boiler, (c4) the cooling water generated in the sulfur combustion furnace and waste heat boiler in the S1 step, (c5) cooling water generated in the step of preparing a solution with sulfuric acid, and (c6) aging water generated in the aging and cutting steps.

[0025] In the above-described method for mass-producing silica gel, the sulfur-containing fuel in the S1 step is high-sulfur coal or high-sulfur petroleum coke powder.

Advantages of the Invention

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects. 1. In the high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention, the hot and humid air in the step of drying silica gel is returned to the dryer or preheating conveyor after being treated and reused for drying silica gel again. In this way, the recycling of heat resources is realized and high-efficiency energy saving is achieved. 2. The high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention further includes a flue gas waste heat recovery module, which is used to recover the thermal energy of the high-temperature flue gas generated in the reverberatory furnace and the sulfur combustion furnace, heat water into steam for utilization, and use it for heating air or heating water. Thereby, the heat resources of the flue gas are utilized, the energy consumption is reduced, and the cost is lowered. 3. The high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention further includes a first wastewater waste heat recovery module that recovers and utilizes the thermal energy generated in the process of preparing raw materials. This module cools high-temperature liquid sodium silicate to a low temperature and uses the thermal energy for heating tap water or chilled water. Also, it cools diluted high-temperature dilute sulfuric acid to a low temperature and uses the thermal energy for heating tap water or chilled water. Thereby, the heat resources generated in the process of preparing raw materials are utilized, and by recovering the thermal energy, it is avoided that the temperature in the gelling process is too high and the non-uniformity of the reaction is avoided. 4. The high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention further includes a second wastewater waste heat recovery module that recovers and utilizes the thermal energy generated in the process of recovering and treating salts. This module is used for washing after treating the water generated in the process of recovering and treating salts, and further recovers and utilizes the thermal energy of the wastewater discharged in the washing process. Thereby, heat resources are saved and the cost is reduced. 5. The high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention further includes a third wastewater waste heat recovery module that recovers and utilizes the thermal energy generated in the process of drying silica gel. This module recovers and utilizes the condensed water generated by the dryer. Thereby, heat resources are saved. 6. The high-efficiency energy-saving manufacturing waste heat recovery and utilization process according to the present invention reduces the energy consumption throughout the process, can generate steam at various temperatures, and has a wide application range. 7. The silica gel mass production method according to the present invention recovers and utilizes silicon, sodium, sulfur, and water, recovers waste heat and waste gas as much as possible, reduces the discharge of waste gas and waste water, realizes zero emissions of carbon and sulfur, protects the environment, realizes the circulation of substances and energy throughout the manufacturing process, reduces energy consumption, reduces manufacturing costs, and can cope with the mass production of silica gel.

Brief Description of the Drawings

[0027] To more clearly explain the technical solutions of the present invention or the prior art, the following briefly describes the drawings necessary for the description of the embodiments or the prior art. However, what is described below is only one embodiment of the present invention, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without creative effort.

Figure 1

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Figure 6

Modes for Carrying Out the Invention

[0028] Hereinafter, with reference to the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. However, it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present invention.

[0029] The high-efficiency energy-saving manufacturing waste heat recovery and utilization system includes a moisture waste heat recovery module that recovers and utilizes the thermal energy of the hot moisture generated in the process of drying substances. The moisture waste heat recovery module includes a conveyor for placing substances, a dryer, a compressor, and / or a heat exchanger. The conveyor sequentially passes through a plurality of dryers, and each dryer is connected to the compressor and / or the heat exchanger via a pipe. The hot moisture generated by the compressor and / or the heat exchanger is recycled for drying substances. In the present invention, the dryer can be any one of a box dryer, a conveyor dryer, a drum dryer, a vertical dryer, a mechanical stirring dryer, a rotary dryer, a fluidized bed dryer, a pneumatic dryer, a vibrating dryer, a spray dryer, a mesh belt dryer, an air-cooled dryer, etc. The compressor includes, but is not limited to, any one of a piston compressor, a screw compressor, a centrifugal compressor, a linear compressor, a scroll compressor, a Roots compressor, etc. The heat exchanger can be any one of a jacket heat exchanger, an immersion coil heat exchanger, a spray heat exchanger, a jacket heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, a double pipe plate heat exchanger, a hybrid heat exchanger, a regenerative heat exchanger, a fluid-connected indirect heat exchanger, a gas-gas heat exchanger, a direct contact heat exchanger, a composite heat exchanger, etc. In the present invention, the substance is silica gel.

[0030] The waste heat generated in the process of manufacturing sodium silicate and the waste heat generated by the manufacturing of silica gel are very precious heat resources. However, in the prior art, there is no system specialized for recovering waste heat energy in the manufacturing of sodium silicate and the manufacturing of silica gel. In the high-efficiency energy-saving manufacturing waste heat recovery and utilization system according to the present invention, the hot moisture generated in the process of drying silica gel is processed by a compressor. The medium and low-temperature hot moisture is compressed to generate hot moisture suitable for drying silica gel and is recycled for drying silica gel. Or the high-temperature hot moisture is processed by a heat exchanger to exchange heat with air to generate hot moisture suitable for drying silica gel and is recycled for drying silica gel. In the present invention, the medium and low-temperature hot moisture refers to water vapor with a temperature of 50-100°C and a moisture mass percentage of 0%-100%. The high-temperature hot moisture refers to water vapor with a temperature exceeding 100°C and a moisture mass percentage of 0%-100%.

[0031] As shown in FIG. 1, in a preferred embodiment of the present invention, the moisture waste heat recovery module specifically includes a preheating conveyor, a first dryer, a second dryer, a third dryer, a first compressor, and a first heat exchanger. The preheating conveyor sequentially passes through the first dryer, the second dryer, and the third dryer. The preheating conveyor, the first dryer, and the second dryer are each connected to the first compressor via a pipe. The second dryer and the third dryer are each connected to the first heat exchanger via a pipe.

[0032] Preferably, the first dryer is a vertical dryer, the second dryer is a mesh belt dryer, the third dryer is an air-cooled dryer, the first compressor is a centrifugal compressor, specifically a steam recompression type compressor, and the first heat exchanger is a gas-gas type heat exchanger. Preferably, the preheating conveyor refers to a conveyor equipped with a heating device inside and capable of preheating while transporting silica gel. In the present invention, the low-temperature wet silica gel is preheated in advance by the preheating conveyor, whereby the product quality can be improved, the drying time can be shortened, the drying effect of silica gel can be improved, and the production amount of silica gel can be improved.

[0033] As shown in FIG. 2, preferably, it further includes a flue gas waste heat recovery module that recovers and utilizes the thermal energy of the high-temperature flue gas generated in the manufacturing process. The flue gas waste heat recovery module includes a waste heat boiler, a second heat exchanger, and a first heat pump. The flue gas inlet end of the waste heat boiler is connected to a sulfur combustion furnace and a reverberatory furnace that generate high-temperature flue gas. Here, the high-temperature flue gas refers to "flue gas with a temperature ≥ 1000°C". The flue gas outlet end of the waste heat boiler is connected to the medium-temperature flue gas inlet end of the second heat exchanger. Here, the medium-temperature flue gas refers to "flue gas with a temperature of 230 - 250°C". The high-temperature air outlet ends of the second heat exchanger are respectively connected to the reverberatory furnace and the sulfur combustion furnace. Here, the high-temperature air refers to "air with a temperature of 230 - 250°C". The flue gas outlet end of the second heat exchanger is connected to the first heat pump. The flue gas at the outlet end of the second heat exchanger is 60°C, and heat exchange treatment is performed by the first heat pump to generate low-temperature flue gas by the first heat pump. Here, the low-temperature flue gas refers to "flue gas with a temperature of 10 - 35°C". The first heat pump is connected to external normal-temperature air and tap water. Here, the normal-temperature air refers to "air with a temperature of 20 - 25°C". The medium-temperature air outlet end of the first heat pump is connected to the second heat exchanger. Here, the medium-temperature air refers to "air with a temperature of 70 - 90°C". Preferably, the second heat exchanger is a gas-gas type heat exchanger. The flue gas waste heat recovery module mainly recovers the thermal energy of the flue gas in the sulfur combustion furnace and the reverberatory furnace, and recycles the recovered thermal energy of the flue gas for the production of sodium silicate, combustion in the sulfur combustion furnace, heating of water for the water washing device, and conversion of heated water into steam, etc.

[0034] In a preferred embodiment of the present invention, the waste heat boiler collects waste heat from the flue gas, pre-treats it, and then it flows into the waste heat boiler for heating or evaporation. Next, the second heat exchanger transfers the waste heat to a medium such as air so that it reaches a predetermined temperature or pressure. In the process of the present invention, the waste heat boiler recovers the thermal energy of the high-temperature flue gas from the reverberatory furnace and the sulfur combustion furnace in order to heat water and use it as steam. Since the second heat exchanger can perform energy transfer between two gases with different temperatures, the cold gas flowing into the second heat exchanger is heated while the hot gas is cooled. In the process of the present invention, the second heat exchanger recovers the thermal energy of the flue gas discharged from the waste heat boiler and uses it for air heating, that is, the medium-temperature flue gas exchanges heat with the medium-temperature air to generate high-temperature air and flue gas with a reduced temperature. The first heat pump is a device that transfers thermal energy from a low-temperature heat source to a high-temperature heat source. It is a mechanical device that forcibly flows thermal energy from a low-temperature object to a high-temperature object in a reverse Carnot cycle. It can supply a larger amount of thermal energy by consuming only a small amount of the net work of the reverse cycle. In the process of the present invention, the thermal energy of the flue gas discharged from the second heat exchanger is further recovered and used for heating water and air. That is, the flue gas with a reduced temperature in the second heat exchanger has further thermal energy recovered by the first heat pump to become low-temperature flue gas, the normal-temperature air is processed by the first heat pump to become medium-temperature air, and the tap water is processed by the first heat pump to become hot water that can be used for washing.

[0035] Preferably, it further includes a first waste water waste heat recovery module that recovers and utilizes the thermal energy generated in the process of preparing the raw materials. The first waste water waste heat recovery module includes a cooler, and the waste water from the tap water or the salt recovery treatment device flows through the cooler to be heated and then flows to the washing device.

[0036] As shown in Fig. 3, in a preferred embodiment of the present invention, the cooler includes an acid cooler and an alkali cooler. The acid cooler is a type of heat exchange equipment, made of acid-resistant substances, used to cool fluids, and generally uses water or air as a coolant to remove thermal energy. In the process of the present invention, the acid cooler cools diluted high-temperature dilute sulfuric acid to a low temperature while heating tap water or cooling water with thermal energy. The alkali cooler is a type of heat exchange equipment, made of alkali-resistant substances, used to cool fluids, and generally uses water or air as a coolant to remove thermal energy. In the process of the present invention, the alkali cooler cools high-temperature liquid sodium silicate to a low temperature while heating tap water or cooling water with thermal energy. The tap water or cooling water heated by the acid cooler and the alkali cooler is used in the water washing process of silica gel. For example, tap water at room temperature of 20°C reaches 35°C after being heated by the acid cooler and the alkali cooler, and then is heated to the water washing temperature required by the process and used in the water washing process. The wastewater obtained by freezing and crystallizing salts has a low temperature of 0 - 2°C, but reaches 35°C after being heated by the acid cooler and the alkali cooler, and then is heated to the water washing temperature required by the process and used in the water washing process.

[0037] Preferably, it further includes a second wastewater waste heat recovery module for recovering and utilizing the thermal energy generated in the process of recovering and treating salts. The second wastewater waste heat recovery module includes a second heat pump and a mixing heater. The second heat pump is connected to the water washing device via a pipeline. The water washing device is connected to the mixing heater via a pipeline. The wastewater generated by the water washing device flows to the salt recovery treatment device after being cooled down by the second heat pump. The high-temperature wastewater from the salt treatment facility, the condensate generated by drying silica gel, and the high-temperature steam generated by the waste heat boiler are mixed in the mixing heater for heat exchange and then flow to the water washing device. Here, the high-temperature wastewater refers to "wastewater with a temperature of 40 - 95°C", and the high-temperature steam here refers to "steam with a temperature of 160°C".

[0038] As shown in Fig. 4, in a preferred embodiment of the present invention, the sodium sulfate brine generated in the water washing process flows through the second heat pump. Due to the action of the second heat pump in this process, the thermal energy of the wastewater discharged in the water washing process is further recovered. For example, the wastewater with a temperature of 35 - 45°C generated in the water washing process becomes water with a temperature of 10 - 20°C and is used in the membrane concentration process. Also, the wastewater with a temperature of 10 - 20°C generated in the membrane concentration becomes water with a temperature of 45 - 80°C and is used in the water washing process. The wastewater from which the thermal energy has been recovered undergoes membrane concentration and desalination treatment, and the desalination treatment method is selected seasonally. In spring, summer, and autumn, an energy-saving technology, the MVR method, which reduces the required external energy by reusing the energy of the secondary steam generated by itself, is adopted. In the process of the present invention, in spring, summer, and autumn, by the MVR method, the high-concentration salt treatment solution after membrane concentration is evaporated and concentrated to evaporate the moisture and obtain sodium sulfate. In winter, the freeze crystallization method is adopted. In freeze crystallization, by lowering the temperature, the liquid is made supersaturated to precipitate crystals, thereby separating the liquid components. In the process of the present invention, in winter, in the freeze crystallization method, sodium sulfate in the high-concentration salt treatment solution after membrane concentration is precipitated as crystals. Preferably, the mixing heater is a steam-water mixing heater, which is a heating device that directly mixes steam with water or other liquids, and uses steam to directly heat water or other liquids to raise the temperature. In the process of the present invention, the mixed steam such as low-temperature tap water, pure water, and condensate is heated to the temperature required by the process. For example, by a mixing heater, steam at 160°C is mixed with tap water, pure water, condensate from MVR, or condensate from the drying process of wet silica gel to generate water with a temperature of 45 - 80°C for use in the water washing process.

[0039] Preferably, it further includes a third wastewater waste heat recovery module that recovers and utilizes the thermal energy generated in the process of drying the silica gel.

[0040] As shown in Fig. 5, in a preferred embodiment of the present invention, the first dryer generates condensed water, and the second dryer also generates condensed water. The above-mentioned condensed water is collected, a part of which is recycled to the water washing process, and the other part is used for heating. For example, the first dryer generates condensed water at a temperature of 60 to 80°C, and the second dryer also generates condensed water at a temperature of 80 to 100°C.

[0041] The present invention provides a high-efficiency energy-saving manufacturing waste heat recovery and utilization process. Heat energy is recovered and utilized using the above-mentioned manufacturing waste heat recovery and utilization system. The manufacturing waste heat recovery and utilization process includes a heat recovery and utilization process of hot and humid air, in which wet substances are placed on a conveyor, and the conveyor sequentially passes through a plurality of dryers for transportation, and the substances are dried by the plurality of dryers to obtain dry substances. The dryers are respectively connected to a compressor and / or a heat exchanger via pipes, and the hot and humid air generated by the compressor and / or the heat exchanger is recycled for drying the substances. Preferably, the conveyor is a preheating conveyor, and the preheating conveyor is connected to a compressor via a pipe. Preferably, the substance of the present invention is silica gel. Preferably, the wet silica gel is placed on the preheating conveyor and conveyed to the first dryer by the preheating conveyor. The first dryer dries the silica gel and sends it to the second dryer. The second dryer further dries the silica gel and then sends it to the third dryer. The third dryer dries the silica gel to generate dry silica gel. The first compressor compresses the medium and low temperature hot and humid air generated by the preheating conveyor, the first dryer, and the second dryer into high temperature hot and humid air. When heat energy is supplemented to the steam, a part of this high temperature hot and humid air is sent to the first dryer for drying the silica gel, and the other part is sent to the first heat exchanger. The high temperature hot and humid air sent to the first heat exchanger exchanges heat with air and then is sent to the second dryer for drying the silica gel. The high temperature hot and humid air generated by the third dryer flows to the preheating conveyor and is used for drying the silica gel.

[0042] The moisture content referred to in the present invention indicates the percentage of the weight of moisture contained in a substance in the total weight of the substance. The relative humidity referred to in the present invention refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the current temperature, reflects how far the air is from saturated air, and represents the percentage of the absolute humidity in the air to the saturated absolute humidity at the same temperature and pressure, that is, it refers to the percentage of the mass of water vapor contained in a certain humid air to the mass of water vapor contained in saturated air at the same temperature and pressure. The water vapor content referred to in the present invention refers to the percentage of the mass of water vapor in humid air in the total mass of the humid air.

[0043] Referring to FIG. 1 again, preferably, the preheating conveyor is for placing wet silica gel with a temperature of 40 to 60°C and a moisture content of 78%. Since the preheating conveyor has a heating effect and exerts a certain drying effect on the silica gel, medium and low temperature hot and humid air with a temperature of 50 to 70°C and a relative humidity exceeding 90% is generated. This medium and low temperature hot and humid air flows into the first compressor, is compressed and heated up. The wet silica gel has its moisture content reduced from 78% to 76%, and then flows into the first dryer. The first dryer is a vertical dryer. Since the silica gel moves vertically downward in the first dryer by its own weight, when the silica gel falls, it is heated by the heating surface it passes through, and its moisture is vaporized. Thus, the purpose of drying the silica gel in the first segment is achieved. At the same time, medium and low temperature hot and humid air with a temperature of 60 to 80°C and a water vapor content of 0% to 100% is generated, flows into the first compressor, is compressed and heated up. The silica gel with a temperature of 80 to 100°C and a moisture content of 60% that has been dried in the first dryer flows into the second dryer, which is a drying facility that continuously dries the silica gel while transporting it using a steel mesh as a conveyor belt. The silica gel is evenly spread on the mesh belt by a feeder and is pulled by a transmission device to move inside the second dryer. The second dryer consists of multiple units. The hot gas passes through the silica gel spread on the mesh belt from bottom to top or from top to bottom, heats and dries it while taking away the moisture. The mesh belt moves slowly, and this operating speed may be adjusted according to the temperature of the silica gel. The dried silica gel continuously falls into a collector. Thus, the purpose of drying the silica gel in the second segment is achieved. In this process, medium and low temperature hot and humid air with a temperature of 80 to 100°C and a relative humidity exceeding 90% is generated, flows into the first compressor, is compressed and heated up. The silica gel with a temperature of 120 to 140°C and a moisture content of 5% that has been dried in the second dryer flows into the third dryer. The third dryer uses normal temperature air to cool down the silica gel and reduces the temperature of the silica gel while recovering heat energy. Such a configuration is useful for the subsequent packaging of the dried silica gel product. Thus, the purpose of drying the silica gel in the third segment is achieved.In addition, air at a temperature of 20°C and a relative humidity of 70% is supplied to the third dryer. The third dryer is an air-cooled dryer. The hot air at a temperature of 100°C and a relative humidity of 1.6% generated by the third dryer is recycled for the drying of silica gel carried out on the preheating conveyor. The above-mentioned medium and low-temperature hot and humid air at a temperature of 50-70°C and a relative humidity exceeding 90% generated by the preheating conveyor, the above-mentioned medium and low-temperature hot and humid air at a temperature of 60-80°C and a water vapor content of 0%-100% generated by the first dryer, and the medium and low-temperature hot and humid air at a temperature of 80-100°C and a relative humidity exceeding 90% generated by the second dryer flow into the first compressor, are compressed and heated up. The generated hot and humid air at a temperature exceeding 100°C and a water vapor content of 0%-100% exchanges heat with the supplied steam at a temperature of 160°C. In the present invention, the steam at a temperature of 160°C may be supplied from the waste heat boiler. Then, hot and humid air at a temperature exceeding 120°C is generated. A part of this hot and humid air is recycled for the drying of silica gel in the first dryer, and the other part flows into the first heat exchanger. The hot and humid air at a temperature exceeding 120°C flowing into the first heat exchanger exchanges heat with the supplied normal-temperature air at a temperature of 20°C and a relative humidity of 70%, generating hot and humid air at a temperature exceeding 100°C and a relative humidity less than 2%, which is recycled for the drying of silica gel in the second dryer.

[0044] In the process of heat recovery and utilization of flue gas, high-temperature flue gas is generated in the reverberatory furnace and the sulfur combustion furnace and flows into the waste heat boiler. The waste heat boiler recovers the heat energy of the high-temperature flue gas to generate medium-temperature flue gas. Next, the medium-temperature flue gas flows into the second heat exchanger for heat exchange. The first heat pump recovers the heat energy of the flue gas discharged from the second heat exchanger. A part of this heat energy of the flue gas is used to heat tap water for use in the water washing process in the water washing device, and the other part is used to heat normal-temperature air to medium-temperature air. The medium-temperature air flows into the second heat exchanger to exchange heat with the medium-temperature flue gas, generating on the one hand flue gas with a reduced temperature that flows into the first heat pump and is further cooled to become low-temperature flue gas, and on the other hand, generating high-temperature air for use in the combustion support of the reverberatory furnace and the sulfur combustion furnace.

[0045] Preferably, high-temperature flue gas with a temperature reaching about 1000°C is generated in the reverberatory furnace and the sulfur combustion furnace and flows into the waste heat boiler. The waste heat boiler recovers the thermal energy of the high-temperature flue gas and generates medium-temperature flue gas at a temperature of 250°C. Next, the medium-temperature flue gas flows into the second heat exchanger for heat exchange. The first heat pump recovers the thermal energy of the flue gas discharged from the second heat exchanger. A part of the thermal energy of this flue gas is used to heat tap water for use in the water washing process, and the other part is used to heat normal-temperature air at 20°C to medium-temperature air at 80°C. The medium-temperature air at 80°C flows into the second heat exchanger for heat exchange with the medium-temperature flue gas at 250°C. A part of it becomes flue gas cooled to 60°C and flows into the first heat pump, where it is further cooled to 15°C to become low-temperature flue gas. The other part generates high-temperature air at 230°C, which is used for assisting combustion in the production of sodium silicate in the reverberatory furnace and for assisting combustion in the combustion of sulfur added to the sulfur combustion furnace.

[0046] In the first waste water heat recovery and utilization process, the cooler recovers the thermal energy generated by concentrated sulfuric acid dilution and sodium silicate melting and heats tap water or frozen crystallization water for use in the water washing process.

[0047] Preferably, the cooler includes an acid cooler that dilutes concentrated sulfuric acid with a concentration exceeding 92.5% to dilute sulfuric acid with a concentration of 20% - 35%, and an alkali cooler for melting solid sodium silicate. A large amount of heat is generated in the process of diluting or dissolving concentrated sulfuric acid and solid sodium silicate before gelation. The acid cooler cools the diluted high-temperature dilute sulfuric acid to a low temperature and heats tap water at 20°C or frozen crystallization water with a temperature of 0 - 2% to water at a temperature of 35°C required for the water washing process using thermal energy. The alkali cooler cools the high-temperature liquid sodium silicate to a low temperature and heats tap water at 20°C or frozen crystallization water with a temperature of 0 - 2% to water at a temperature of 35°C required for the water washing process using thermal energy.

[0048] In the second waste water heat recovery and utilization process, the sodium sulfate brine generated in the water washing process flows through the second heat pump, and the second heat pump further recovers the thermal energy of the waste water discharged in the water washing process.

[0049] Preferably, the sodium sulfate brine generated in the water washing process flows through the second heat pump, and the second heat pump further recovers the thermal energy of the wastewater discharged in the water washing process at a temperature of 35 to 45°C. The wastewater at a temperature of 10 to 20°C from which the thermal energy has been recovered undergoes membrane concentration and desalination treatment, and the desalination treatment method is selected seasonally. In spring, summer, and autumn, the MVR method is adopted. In the MVR method, the high-concentration salt treatment solution after membrane concentration is evaporated and concentrated to evaporate water and obtain sodium sulfate. In winter, the freeze crystallization method is adopted. In the freeze crystallization method, sodium sulfate in the high-concentration salt treatment solution after membrane concentration is precipitated as crystals. The mixing heater mixes low-temperature tap water, pure water, condensate, etc. with steam at a temperature of 160°C, heats it to the temperature required for the process, and supplies it to the water washing process. In the present invention, the steam at a temperature of 160°C is supplied from the waste heat boiler. A part of the steam at a temperature of 160°C is used in the heat recovery process of the second wastewater, and the other part is used to supplement the steam in the heat recovery and utilization process of the hot and humid air.

[0050] In the heat recovery and utilization process of the third wastewater, the condensate generated by the first dryer and the second dryer is collected and supplied to the water washing process or heating.

[0051] Preferably, the first dryer generates condensate at a temperature of 60 to 80°C, and the second dryer generates condensate at a temperature of 80 to 100°C. The above condensate is collected, and a part of it may be recycled to the water washing process, and the other part may be used for heating.

[0052] Calculated based on an annual production volume of 300,000 tons of silica gel, the moisture waste heat recovery module can recover and utilize 2.8 million GJ of thermal energy, the flue gas waste heat recovery module can recover and utilize 3 million GJ of thermal energy, the first wastewater waste heat recovery module can recover and utilize 195,000 GJ of thermal energy, the second wastewater waste heat recovery module can recover and utilize 435,000 GJ of thermal energy, and the third waste heat recovery module can recover and utilize 415,000 GJ of thermal energy. Here, the thermal energy recovered and utilized by the flue gas waste heat recovery module is the most, accounting for 43.8% of the total amount of thermal energy recovered and utilized. The moisture waste heat recovery module can recover and utilize the next largest amount of thermal energy, accounting for 40.9% of the total amount of thermal energy recovered and utilized. The thermal energy that the second wastewater waste heat recovery module can recover and utilize accounts for 6.4% of the total amount of thermal energy recovered and utilized. The thermal energy that the third wastewater waste heat recovery module can recover and utilize accounts for 6.1% of the total amount of thermal energy recovered and utilized. The thermal energy that the first wastewater waste heat recovery module can recover and utilize accounts for 2.8% of the total amount of thermal energy recovered and utilized.

[0053] As shown in FIG. 6, based on the same technical concept, the present invention also provides a mass production method of silica gel including using the above high-efficiency energy-saving manufacturing waste heat recovery and utilization process, and the method includes the following steps.

[0054] In S1, a silicon source, a sodium salt, and a sulfur-containing fuel are reacted in a reverberatory furnace at a reaction temperature of 1350-1400° C. at a predetermined ratio to generate sodium silicate and generate flue gas rich in sulfur dioxide.

[0055] In S2, sulfur is added, an appropriate amount of air is supplemented and combusted to make the sulfur dioxide in the flue gas reach a certain concentration. Specifically, the flue gas rich in sulfur dioxide in step S1 is introduced into the waste heat boiler, sulfur is added to the sulfur combustion furnace, an appropriate amount of air is supplemented, and combustion continues at about 1000 °C. The generated sulfur dioxide flue gas is also introduced into the waste heat boiler. After the heat energy of the flue gas from the outlets of the reverberatory furnace and the sulfur combustion furnace is recovered by the waste heat boiler, the temperature of the flue gas is reduced to 230 - 250 °C, and the sulfur dioxide concentration of the flue gas reaches 5.6% by volume or more. Then it enters the acid washing and purification section, the dust in the flue gas is removed by purification, the temperature of the flue gas is reduced to 35 °C or below, dried and dehydrated with concentrated sulfuric acid, then introduced into the converter, converted to sulfur trioxide with a vanadium catalyst, and finally absorbed in the absorption tower at a temperature of 60 °C using concentrated sulfuric acid with a mass percentage of 98% to obtain industrial sulfuric acid.

[0056] In the prior art, it is necessary to control the concentration of sulfur dioxide to remove exhaust gas. Desulfurization treatment is carried out by the alkali liquid absorption method, the catalyst method, and the ammonia water absorption method, but the desulfurization efficiency is insufficient, the economic investment and results are disproportionate, and the concentration of sulfur dioxide after treatment greatly deviates from the emission standards. On the other hand, in the present invention, a method opposite to the prior art is adopted. By adding sulfur, sulfur dioxide in the exhaust gas is treated, while sulfur is used for preparing sulfuric acid. In the prior art, it is disclosed to prepare sulfuric acid using sulfur dioxide in the exhaust gas, but in order to ensure the quality of the produced sulfuric acid, the above-mentioned all-oxygen combustion type air separation equipment is used. This equipment has a large occupied area, high cost, and the cost of all-oxygen combustion is not suitable for actual production either. Theoretically, it cannot be converted into productivity, which is disadvantageous for industrial mass production. Also, the reason for reducing the temperature of the flue gas to 230 - 250 °C is to ensure the operation stability when preparing sulfuric acid. If the temperature is too high, exceeding 250 °C, a load will be imposed on the subsequent transport pipeline and sulfuric acid purification equipment. If the temperature is lower than 230 °C, sulfurous acid will be generated in the process of preparing sulfuric acid. If the temperature is lower than the acid dew point temperature of the flue gas, it will cause corrosion to the equipment and also lead to risks during the operation of the equipment.

[0057] In S3, a solution is prepared using the sodium silicate generated in step S1 and the sulfuric acid obtained in step S2, followed by gelation, aging, cutting, washing with water, and drying to produce dry silica gel. In the step of drying the silica gel, the heat energy of the hot and humid air is recovered and utilized using the above-mentioned waste heat recovery and utilization system, and recycled for the drying of substances.

[0058] Preferably, it further includes a step of recovering and utilizing the heat of flue gas. The high-temperature flue gas generated in the reverberatory furnace in step S1 and the sulfur combustion furnace in step S2 is introduced into a waste heat boiler, and the heat energy of the high-temperature flue gas is recovered by the waste heat boiler to generate medium-temperature flue gas. Next, the medium-temperature flue gas is introduced into a second heat exchanger for heat exchange. The heat energy of the flue gas discharged from the second heat exchanger is recovered by a first heat pump. A part of the heat energy is used to heat tap water for use in the water washing process, and another part is used to heat normal-temperature air to medium-temperature air, and the medium-temperature air is introduced into the second heat exchanger to exchange heat with the medium-temperature flue gas to generate low-temperature flue gas, which is introduced into the first heat pump to further reduce the temperature to low-temperature flue gas, while generating high-temperature air for use in the combustion support of the reverberatory furnace and the sulfur combustion furnace.

[0059] Preferably, it further includes a step of recovering and utilizing the heat of the first wastewater. The heat energy generated by diluting concentrated sulfuric acid and melting sodium silicate is recovered by a cooler in the gelation process in step S3 to heat tap water and freeze-crystallized water for use in the water washing process.

[0060] Preferably, it further includes a step of recovering and utilizing the heat of the second wastewater. The sodium sulfate brine generated in the water washing process in step S3 is introduced into a second heat pump, and the heat energy of the wastewater discharged in the water washing process is further recovered by the second heat pump.

[0061] Preferably, it further includes a step of recovering and utilizing the heat of the third wastewater. In the drying process in step S3, the condensed water generated by the first dryer and the second dryer is supplied to the water washing process or heating.

[0062] Preferably, the silicon source in the S1 step is any one selected from (a1) quartz sand, (a2) waste silica gel generated in the step of manufacturing dry silica gel, (a3) waste wet silica gel generated in the steps of aging and cutting, (a4) alkaline mud precipitated by filtration during solution preparation with sodium silicate, and (a5) polysilicon slag.

[0063] Preferably, the sodium salt in the S1 step is any one selected from (b1) sodium sulfate decahydrate after desalting the sodium sulfate brine generated in the water washing process, (b2) anhydrous sodium sulfate after desalting the sodium sulfate brine generated in the water washing process, (b3) sulfur-containing solid waste sodium salts such as sodium thiosulfate, sodium thiocyanate, and sodium sulfite, and (b4) any one selected from the quenching liquid generated in the quenching tank in the process of manufacturing sodium silicate. More preferably, the sodium salt in the S1 step is any one selected from (b1) sodium sulfate decahydrate after desalting the sodium sulfate brine generated in the water washing process and (b2) anhydrous sodium sulfate after desalting the sodium sulfate brine generated in the water washing process.

[0064] Preferably, in the water washing process in the S3 step, the water used in the water washing process is any one or more selected from (c1) wastewater generated in the treated water washing process, (c2) water condensed from the water vapor generated in the silica gel drying process, (c3) condensed water generated in the sulfur combustion furnace and waste heat boiler, (c4) cooling water generated in the sulfur combustion furnace and waste heat boiler in the S1 step, (c5) cooling water generated in the process of preparing a solution with sulfuric acid, and (c6) aging water generated in the aging and cutting processes.

[0065] Preferably, the sulfur-containing fuel in the S1 step is high-sulfur coal or high-sulfur petroleum coke powder. In the prior art, there are many problems when using high-sulfur coal or high-sulfur petroleum coke powder as follows. Combustion produces SO 2 or SO 3is generated and easily combines with water vapor to form sulfuric acid vapor, resulting in serious corrosion of combustion equipment. Therefore, the requirements for the equipment become stricter. The generated SO 2 or SO 3 When discharged into the air, it causes serious air pollution. It is prone to spontaneous combustion and deterioration during storage, affecting the combustion effect. Therefore, due to the above problems, high-sulfur coal or high-sulfur petroleum coke powder is hardly used in production. On the other hand, in the present application, high-sulfur coal or high-sulfur petroleum coke powder is not only used as a fuel but also provides sulfur elements and is applied to improving the concentration of sulfur dioxide for preparing sulfuric acid. Since sulfur dioxide does not affect the corrosion of the equipment due to temperature limitations and there is no environmental pollution caused by exhaust gas, it enhances the utilization value of waste resources. Example 1

[0066] This example provides a high-efficiency energy-saving manufacturing waste heat recovery and utilization system including a moisture waste heat recovery module R-4 that recovers and utilizes the thermal energy of the hot moisture generated in the process of drying silica gel.

[0067] As shown in FIG. 1, specifically, the moisture waste heat recovery module R-4 includes a preheating conveyor 1, a first dryer 2, a second dryer 3, a third dryer 4, a first compressor 5, and a first heat exchanger 6. The preheating conveyor 1 sequentially passes through the first dryer 2, the second dryer 3, and the third dryer 4. The preheating conveyor 1, the first dryer 2, and the second dryer 3 are respectively connected to the first compressor 5 via pipes. The second dryer 3 and the third dryer 4 are respectively connected to the first heat exchanger 6 via pipes. In this example, specifically, the first dryer 2 is a vertical dryer, the second dryer 3 is a mesh belt dryer, the third dryer 4 is an air-cooled dryer, the first compressor 5 is a steam recompression type compressor, and the first heat exchanger 6 is a gas-gas type heat exchanger.

[0068] As shown in FIG. 2, it further includes a flue gas waste heat recovery module R-1 that recovers and utilizes the thermal energy of the high-temperature flue gas generated in the manufacturing process. The flue gas waste heat recovery module R-1 includes a waste heat boiler 7, a second heat exchanger 8, and a first heat pump 9. The flue gas inlet end of the waste heat boiler 7 is connected to a reverberatory furnace 10 and a sulfur combustion furnace 12 that generate high-temperature flue gas. The flue gas outlet end of the waste heat boiler 7 is connected to the medium-temperature flue gas inlet end of the second heat exchanger 8. The high-temperature air outlet ends of the second heat exchanger 8 are respectively connected to the reverberatory furnace 10 and the sulfur combustion furnace 12. The medium-temperature flue gas outlet end of the second heat exchanger 8 is connected to the first heat pump 9. The first heat pump 9 is connected to external normal-temperature air and tap water. The medium-temperature air outlet end of the first heat pump 9 is connected to the second heat exchanger 8. In this embodiment, the second heat exchanger 8 is preferably a gas-gas heat exchanger.

[0069] As shown in FIG. 3, it further includes a first wastewater waste heat recovery module R-2 that recovers and utilizes the thermal energy generated in the process of preparing raw materials. The first wastewater waste heat recovery module R-2 includes a cooler. Wastewater from tap water or a salt recovery treatment device flows through the cooler, is heated up, and then flows to a water washing device 13. The cooler includes an acid cooler 15 and an alkali cooler 14. The acid cooler 15 cools the diluted high-temperature dilute sulfuric acid to a low temperature and heats tap water or cooling water with thermal energy. The alkali cooler 14 cools the high-temperature liquid sodium silicate to a low temperature and heats tap water or cooling water with thermal energy. The tap water or cooling water heated by the acid cooler 15 and the alkali cooler 14 is used in the water washing process of silica gel.

[0070] As shown in FIG. 4, it further includes a second wastewater waste heat recovery module R-3 that recovers and utilizes the thermal energy generated in the process of recovering salt. The second wastewater waste heat recovery module R-3 includes a second heat pump 16 and a mixing heater 17. The second heat pump 16 is connected to the water washing device 13 via a pipe. The water washing device 13 is connected to the mixing heater 17 via a pipe. The wastewater generated by the water washing device 13 flows to the salt recovery treatment device after being cooled by the heat pump. The high-temperature wastewater from the salt treatment facility, the condensed water generated by drying the silica gel, and the steam generated by the waste heat boiler 7 are mixed in the mixing heater 17 for heat exchange and then flow to the water washing device 13. In this embodiment, the mixing heater 17 is preferably an air-water mixing heater.

[0071] As shown in FIG. 5, it further includes a third wastewater waste heat recovery module R-5 that recovers and utilizes the thermal energy generated in the process of drying the silica gel. Example 2

[0072] The present invention provides a high-efficiency energy-saving manufacturing waste heat recovery and utilization process. The manufacturing waste heat recovery and utilization process uses the manufacturing waste heat recovery and utilization system described in Example 1 to recover and utilize thermal energy, and includes the following thermal energy recovery and utilization processes for hot and humid air, flue gas heat recovery and utilization process, first wastewater heat recovery and utilization process, second wastewater heat recovery and utilization process, and third wastewater heat recovery and utilization process.

[0073] In the process of heat recovery and utilization of hot and humid air, wet silica gel is placed on a conveyor, and the conveyor sequentially passes through a plurality of dryers for transportation. The silica gel is dried by the plurality of dryers to obtain dry silica gel. The process of heat recovery and utilization of hot and humid air is included. The conveyor and the dryer are respectively connected to a compressor or a heat exchanger through pipes. The hot and humid air generated by the compressor and / or the heat exchanger is recycled for drying the silica gel. Preferably, the wet silica gel is placed on a preheating conveyor 1 and conveyed to a first dryer 2 by the preheating conveyor 1. The first dryer 2 dries the silica gel and conveys it to a second dryer 3. The second dryer 3 further dries the silica gel and then conveys it to a third dryer 4. The third dryer 4 dries the silica gel to produce dry silica gel. The first compressor 5 compresses the medium and low temperature hot and humid air generated by the preheating conveyor 1, the first dryer 2, the second dryer 3, and the third dryer 4 into high temperature hot and humid air. After heat energy is supplemented to the steam, a part of this high temperature hot and humid air is sent to the first dryer 2 for use in drying the silica gel, and the other part is sent to the first heat exchanger 6. The high temperature hot and humid air sent to the first heat exchanger 6 exchanges heat with air and then is sent to the second dryer 3 for use in drying the silica gel. The high temperature hot and humid air generated by the third dryer 4 is sent to the preheating conveyor 1 for use in drying the silica gel.

[0074] Specifically, the preheating conveyor is for placing wet silica gel with a temperature of 40 to 60°C and a moisture content of 78%. The preheating conveyor 1 has a heating effect and exerts a certain drying effect on the silica gel. Therefore, medium and low-temperature hot and humid air with a temperature of 50 to 70°C and a relative humidity exceeding 90% is generated. This medium and low-temperature hot and humid air flows into the first compressor 5, is compressed and heated up. After the moisture content of the wet silica gel drops from 78% to 76%, it flows into the first dryer 2. The first dryer 2 is a vertical dryer. Since the silica gel moves vertically downward in the first dryer 2 due to its own weight, thereby, when the silica gel falls, it is heated by the heating surface it passes through, and its moisture is also vaporized. Thus, the purpose of drying the silica gel in the first segment is achieved. Also, medium and low-temperature hot and humid air with a temperature of 60 to 80°C and a water vapor content of 0% to 100% is generated, flows into the first compressor 5, is compressed and heated up. The silica gel with a temperature of 80 to 100°C and a moisture content of 60% that has been dried in the first dryer 2 flows into the second dryer 3, which is a drying facility that continuously dries the silica gel while transporting it with a steel mesh as a conveyor belt. The silica gel is evenly spread on the mesh belt by a feeder and is pulled by a transmission device to move inside the second dryer 3. The second dryer 3 consists of multiple units. The hot gas passes through the silica gel spread on the mesh belt from bottom to top or from top to bottom, heats and dries it, and takes away the moisture. The mesh belt moves slowly, and this operating speed may be adjusted according to the temperature of the silica gel. The dried silica gel continuously falls into a collector. Thus, the purpose of drying the silica gel in the second segment is achieved. In this process, medium and low-temperature hot and humid air with a temperature of 80 to 100°C and a relative humidity exceeding 90% is generated, flows into the first compressor 5, is compressed and heated up. The silica gel with a temperature of 120 to 140°C and a moisture content of 5% that has been dried in the second dryer 3 flows into the third dryer 4. The third dryer 4 uses normal-temperature air to cool down the silica gel and reduces the temperature of the silica gel while recovering thermal energy. With such a configuration, it is useful for the subsequent packaging of the dried silica gel product. Thus, the purpose of drying the silica gel in the third segment is achieved.In addition, air at a temperature of 20°C and a relative humidity of 70% is supplied to the third dryer 4, which is an air-cooled dryer. The hot air at a temperature of 100°C and a relative humidity of 1.6% generated by the third dryer 4 is recycled for the drying of silica gel carried out on the preheating conveyor 1. The above-mentioned medium and low-temperature hot and humid air at a temperature of 50 - 70°C and a relative humidity exceeding 90% generated by the preheating conveyor 1, the above-mentioned medium and low-temperature hot and humid air at a temperature of 60 - 80°C and a water vapor content of 0% - 100% generated by the first dryer 2, and the medium and low-temperature hot and humid air at a temperature of 80 - 100°C and a relative humidity exceeding 90% generated by the second dryer 2 flow into the first compressor 5, are compressed and heated up. The generated high-temperature hot and humid air at a temperature exceeding 100°C and a water vapor content of 0% - 100% exchanges heat with the supplied steam at a temperature of 160°C. In the present invention, the steam at a temperature of 160°C may be supplied from the waste heat boiler 7. Thereafter, high-temperature hot and humid air with a temperature exceeding 120°C is generated. A part of this high-temperature hot and humid air is recycled for the drying of silica gel in the first dryer 2, and the other part flows into the first heat exchanger 6. The high-temperature hot and humid air with a temperature exceeding 120°C flowing into the first heat exchanger 6 exchanges heat with the supplied normal-temperature air at a temperature of 20°C and a relative humidity of 70%, generating high-temperature hot and humid air at a temperature exceeding 100°C and a relative humidity less than 2%, which is recycled for the drying of silica gel in the second dryer 3.

[0075] In the process of heat recovery and utilization of flue gas, high-temperature flue gas at a temperature of about 1000°C is generated in the reverberatory furnace 10 and the sulfur combustion furnace 12, flows into the waste heat boiler 7. The waste heat boiler 7 recovers the thermal energy of the high-temperature flue gas, generating medium-temperature flue gas at a temperature of 250°C. Next, the medium-temperature flue gas flows into the second heat exchanger 8 for heat exchange. The first heat pump 9 recovers the thermal energy of the flue gas discharged from the second heat exchanger 8. A part of this thermal energy of the flue gas is used to heat tap water for use in the water washing process, and the other part is used to heat normal-temperature air at 20°C to medium-temperature air at 80°C. The medium-temperature air at 80°C flows into the second heat exchanger 8 and exchanges heat with the medium-temperature flue gas at 250°C. A part of it becomes flue gas cooled to 60°C, flows into the first heat pump 9 and is further cooled to become low-temperature flue gas at 15°C. The other part generates high-temperature air at 230°C, which is used for the combustion support of the reverberatory furnace 10 and the sulfur combustion furnace 12.

[0076] In the first waste water heat recovery and utilization process, the cooler includes an acid cooler 15 that dilutes concentrated sulfuric acid with a concentration exceeding 92.5% to dilute sulfuric acid with a concentration of 20% - 35%, and an alkali cooler 15 for melting solid sodium silicate. A large amount of heat is generated during the dilution or dissolution process of concentrated sulfuric acid and solid sodium silicate before gelation. The acid cooler 15 cools the diluted high-temperature dilute sulfuric acid to a low temperature, and heats tap water at a temperature of 20°C or frozen crystallization water at a temperature of 0 - 2% to water at a temperature of 35°C with thermal energy, and then heats it to the process temperature required for the water washing process and supplies it to the water washing process. The alkali cooler 14 cools the high-temperature liquid sodium silicate to a low temperature, and heats tap water at a temperature of 20°C or frozen crystallization water at a temperature of 0 - 2% to water at a temperature of 35°C with thermal energy, and then heats it to the process temperature required for the water washing process and supplies it to the water washing process.

[0077] In the second waste water heat recovery and utilization process, the sodium sulfate brine generated in the water washing process flows through the second heat pump 16, and the second heat pump 16 further recovers the thermal energy of the waste water discharged at a temperature of 35 - 45°C in the water washing process. The waste water at a temperature of 10 - 20°C with the thermal energy recovered undergoes membrane concentration and desalination treatment, and the desalination treatment method is selected seasonally. In spring, summer, and autumn, the MVR method is adopted. In the MVR method, the high-concentration salt treatment solution after membrane concentration is evaporated and concentrated to evaporate water to obtain sodium sulfate. In winter, the freezing crystallization method is adopted. In the freezing crystallization method, sodium sulfate in the high-concentration salt treatment solution after membrane concentration is precipitated as crystals. The mixing heater mixes low-temperature tap water, pure water, condensate, etc. with steam at a temperature of 160°C, heats it to the temperature required for the process, and supplies it to the water washing process. In the present invention, the steam at a temperature of 160°C is supplied from the waste heat boiler 7. A part of the steam at a temperature of 160°C is used in the heat recovery process of the second waste water, and the other part is used to supplement steam in the heat recovery and utilization process of hot and humid air.

[0078] In the process of heat recovery and utilization of the third wastewater, the first dryer 2 generates condensed water at a temperature of 60 to 80°C, and the second dryer 3 generates condensed water at a temperature of 80 to 100°C. The above condensed water is collected, and a part of it is recycled to the water washing process of the water washing device 13, and the other part is used for heating.

[0079] Converted based on an annual production volume of 300,000 tons of silica gel, the moisture waste heat recovery module can recover and utilize 2.8 million GJ of thermal energy, the flue gas waste heat recovery module can recover and utilize 3 million GJ of thermal energy, the first wastewater waste heat recovery module can recover and utilize 195,000 GJ of thermal energy, the second wastewater waste heat recovery module can recover and utilize 435,000 GJ of thermal energy, and the third waste heat recovery module can recover and utilize 415,000 GJ of thermal energy. Example 3

[0080] This example also provides a method for mass-producing silica gel, which specifically includes the following steps as shown in FIG. 6.

[0081] In S1, in this example, the silicon source is selected as quartz sand, the sodium salt is selected as anhydrous sodium sulfate obtained by desalting the sodium sulfate brine generated in the water washing process, and the sulfur-containing fuel is high-sulfur coal with a sulfur mass percentage of 8%. The silicon source, sodium salt, and sulfur-containing fuel are introduced into the regenerative reflector furnace at a ratio of 7:4.3:2, and the mixture is allowed to stay in the furnace for 4 hours while maintaining the furnace temperature at 1400°C. The generated sodium silicate molten salt overflows from the outlet and is cooled in the water quenching tank 11 to obtain sodium silicate with an elastic modulus of 3.2 and a mass percentage of water-insoluble substances of 1.64%, and generate flue gas with a volume percentage of sulfur dioxide content of 2.17%.

[0082] In S2, the flue gas rich in sulfur dioxide in step S1 is introduced into the waste heat boiler 7, and using a liquid sulfur spray gun, it is sprayed into the sulfur combustion furnace 12 to add 45 kg of molten sulfur per 1000 cubic meters of flue gas, an appropriate amount of air is supplemented, and combustion continues at about 1000 °C. The generated sulfur dioxide flue gas is also introduced into the waste heat boiler 7. The high-temperature flue gas at about 1000 °C at the outlets of the sulfur combustion furnace 12 and the reverberatory furnace 10 has its thermal energy recovered by the waste heat boiler 7, and the flue gas is cooled down to 230 - 250 °C. Preferably, the high-temperature flue gas at about 1000 °C is cooled down to medium-temperature flue gas at 250 °C, and the sulfur dioxide concentration in the flue gas becomes 5.6% by volume. Then it enters the acid washing and purification section to remove the dust in the flue gas by purification, is cooled down to 35 °C or lower by a gas-gas heat exchanger, preferably to low-temperature flue gas at 15 °C, dried and dehydrated with concentrated sulfuric acid, then flows into a converter and is converted into sulfur trioxide with a vanadium catalyst. Finally, it is absorbed in an absorption tower at a temperature of 60 °C using concentrated sulfuric acid with a mass percentage of 98% to obtain industrial sulfuric acid with a concentration exceeding 92.5% and meeting the qualified product requirements specified in GB / T 534 - 2014.

[0083] In S3, a solution is prepared using the sodium silicate produced in step S1 and the sulfuric acid obtained in step S2, followed by gelation, aging, cutting, water washing, and drying to produce dry silica gel. Specifically, in the water washing step in the S3 step, the water used in the water washing step is the treated wastewater generated in the water washing step.

[0084] The silica gel mass production method according to this example further includes using the high-efficiency energy-saving manufacturing waste heat recovery and utilization process described in Example 2. Specifically, it includes a heat recovery and utilization process for hot and humid air, a heat recovery and utilization process for flue gas, a heat recovery and utilization process for the first wastewater, a heat recovery and utilization process for the second wastewater, and a heat recovery and utilization process for the third wastewater.

[0085] According to this example, silica gel meeting the index requirements in the silica gel industry standard HG / T2765.1 - 2765.6 - 2005 is produced.

[0086] The method for mass-producing silica gel according to this embodiment forms an environmentally friendly cycle in the process of manufacturing silica gel, without the discharge of waste water, waste gas and solid waste, realizes the circulation of sulfur element, sodium element and silicon element, and also realizes the circulation of water resources and heat resources, achieving efficiency improvement and high-efficiency energy saving, and is suitable for industrial mass production.

[0087] Note that the above is only a preferred embodiment of the present invention, and without departing from the principle of the present invention, some improvements and modifications are possible for those skilled in the art, and these improvements and modifications should also be regarded as within the protection scope of the present invention.

Explanation of Signs

[0088] 1 Preheating conveyor 2 First dryer 3 Second dryer 4 Third dryer 5 First compressor 6 First heat exchanger 7 Waste heat boiler 8 Second heat exchanger 9 First heat pump 10 Reverberatory furnace 11 Water quenching tank 12 Sulfur combustion furnace 13 Water washing device 14 Alkali cooler 15 Acid cooler 16 Second heat pump 17 Mixing heater

Claims

1. A highly efficient, energy-saving manufacturing waste heat recovery and utilization system, The moisture waste heat recovery module (R-4) recovers and utilizes the heat energy of heat and moisture generated in the process of drying the material, the moisture waste heat recovery module (R-4) includes a conveyor for placing the material, a dryer, a compressor, and / or a heat exchanger, the conveyor passes through a plurality of dryers in sequence, the dryers are connected to the compressor and / or the heat exchanger via piping, and the heat and moisture generated in the compressor and / or the heat exchanger are recycled to dry the material, The moisture waste heat recovery module (R-4) specifically includes a preheating conveyor (1), a first dryer (2), a second dryer (3), a third dryer (4), a first compressor (5), and a first heat exchanger (6), the preheating conveyor (1) passes through the first dryer (2), the second dryer (3), and the third dryer (4) in sequence, the preheating conveyor (1), the first dryer (2), and the second dryer (3) are each connected to the first compressor (5) via piping, the second dryer (3) and the third dryer (4) are each connected to the first heat exchanger (6) via piping, and the material is silica gel.

2. The manufacturing waste heat recovery and utilization system includes: The system further includes a flue gas waste heat recovery module (R-1) for recovering and utilizing the thermal energy of high-temperature flue gas generated in the manufacturing process, the flue gas waste heat recovery module (R-1) including a waste heat boiler (7), a second heat exchanger (8), and a first heat pump (9), the waste heat boiler (7) having a flue gas inlet connected to a reverberatory furnace (10) and a sulfur combustion furnace (12) for generating high-temperature flue gas, and the waste heat boiler (7) having a flue gas outlet connected to a medium-temperature flue gas inlet of a second heat exchanger (8). a high-temperature air outlet end of the second heat exchanger (8) connected to a reverberatory furnace (10) and a sulfur combustion furnace (12), respectively; a flue gas outlet end of the second heat exchanger (8) connected to a first heat pump (9), the first heat pump (9) connected to external room temperature air and tap water, and a medium temperature air outlet end of the first heat pump (9) connected to the second heat exchanger (8).

3. The manufacturing waste heat recovery and utilization system includes: The highly efficient and energy-saving production waste heat recovery and utilization system according to claim 1, further comprising a first wastewater waste heat recovery module (R-2) for recovering and utilizing thermal energy generated in the process of preparing raw materials, the first wastewater waste heat recovery module (R-2) including a cooler, in which tap water or wastewater from a salt recovery and treatment device flows through the cooler to be heated and then flows into a water washing device (13).

4. The manufacturing waste heat recovery and utilization system includes:

4. The highly efficient, energy-saving production waste heat recovery and utilization system according to claim 3, further comprising a second wastewater waste heat recovery module (R-3) for recovering and utilizing thermal energy generated in the salt recovery process, the second wastewater waste heat recovery module (R-3) including a second heat pump (16) and a mixer heater (17), the second heat pump (16) being connected to a water washing device (13) via piping, and the water washing device (13) being connected to the mixer heater (17) via piping.

5. The manufacturing waste heat recovery and utilization system includes: The highly efficient and energy-saving manufacturing waste heat recovery and utilization system according to claim 4, further comprising a third wastewater waste heat recovery module (R-5) for recovering and utilizing the thermal energy generated in the process of drying the silica gel.

6. A highly efficient and energy-saving manufacturing waste heat recovery and utilization process, Using the manufacturing waste heat recovery and utilization system according to claim 1 to recover and utilize thermal energy, The manufacturing waste heat recovery and utilization process includes: The method includes a heat recovery and utilization process of placing a wet material on a conveyor, transporting the wet material through a plurality of dryers in sequence, and drying the wet material in the plurality of dryers to obtain a dry material, A highly efficient and energy-saving manufacturing waste heat recovery and utilization process, characterized in that the conveyor and dryer are each connected to a compressor and / or a heat exchanger via piping, and the heat and moisture generated in the compressor and / or heat exchanger is recycled for drying materials.

7. A method for mass-producing silica gel, comprising the steps of: Step S1: reacting a silicon source, a sodium salt, and a sulfur-containing fuel in a predetermined ratio at a specific reaction temperature to produce sodium silicate and generate flue gas rich in sulfur dioxide; Step S2: the flue gas rich in sulfur dioxide in step S1 is fed into the residual heat boiler, sulfur is added to the sulfur combustion furnace, and an appropriate amount of air is added to continue burning at about 1000°C; the generated sulfur dioxide flue gas is also fed into the residual heat boiler; the flue gas from the outlet of the reverberatory furnace and the sulfur combustion furnace is cooled to 230-250°C after the thermal energy is recovered by the residual heat boiler, and the sulfur dioxide concentration of the flue gas is 5.6% by volume or more; and then the flue gas enters the acid washing section, is purified, dried, and fed into the converter, is converted into sulfur trioxide by catalytic conversion, and finally is absorbed with concentrated sulfuric acid to obtain industrial sulfuric acid; A method for mass-producing silica gel, comprising the steps of: preparing a solution using the sodium silicate produced in step S1 and the sulfuric acid obtained in step S2; gelling the solution; aging, cutting, washing with water, and drying the solution to produce dried silica gel; and in the process of drying the silica gel, recovering and utilizing the thermal energy of the heat and moisture using the production waste heat recovery and utilization system described in claim 1, and recycling the recovered thermal energy for drying materials.

8. 8. The method for mass-producing silica gel according to claim 7, characterized in that the silicon source in step S1 is selected from the group consisting of: (a1) quartz sand; (a2) dried silica gel scraps produced in the step of producing dried silica gel in step S3; (a3) ​​wet silica gel scraps produced in the step of aging and cutting in step S3; (a4) alkaline mud precipitated by filtration during the preparation of a solution with sodium silicate in step S3; and (a5) polysilicon slag.

9. 8. The method for mass-producing silica gel according to claim 7, wherein the sodium salt in step S1 is selected from the group consisting of: (b1) sodium sulfate decahydrate obtained by desalting the sodium sulfate salt water produced in the water-washing step in step S3; (b2) anhydrous sodium sulfate obtained by desalting the sodium sulfate salt water produced in the water-washing step in step S3; (b3) sodium salts of sulfur-containing solid waste, such as sodium thiosulfate, sodium thiocyanate, and sodium sulfite; and (b4) a water quenching liquid produced in a water quenching tank in the step of producing sodium silicate in step S3.

10. The method for mass-producing silica gel according to claim 7, characterized in that in the water-washing step in step S3, the water used in the water-washing step is selected from the group consisting of: (c1) wastewater generated in the treated water-washing step; (c2) water obtained by condensing steam generated in the silica gel drying step in step S3; (c3) condensed water generated in the sulfur combustion furnace and waste heat boiler in step S3; (c4) temperature-reducing water generated in the sulfur combustion furnace and waste heat boiler in step S2; (c5) cooling water generated in the step of preparing a solution using sulfuric acid in step S3; and (c6) aged water generated in the aging and cutting step in step S3.

11. 8. The method for mass-producing silica gel according to claim 7, wherein the sulfur-containing fuel in step S1 is high-sulfur coal or high-sulfur petroleum coke powder.

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