Highly efficient energy-saving manufacturing waste heat recovery and utilization system and its process, and silica gel mass production method

Abstract

We provide a highly efficient, energy-saving manufacturing waste heat recovery and utilization system. [Solution] The present invention includes a moisture waste heat recovery module that recovers and utilizes the thermal energy of heat and moisture generated in the process of drying a material, the moisture waste heat recovery module 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 for drying the material. The present invention also provides a method for mass-producing silica gel. The method for mass-producing silica gel according to the present invention forms an environmentally friendly circulation in the process of producing silica gel, does not discharge wastewater, waste gas and solid waste, realizes the circulation of sulfur, sodium and silicon elements, and also realizes the circulation of water and heat resources, achieves high efficiency and energy saving, and is suitable for industrial mass production.

Description

[Technical field]

[0001] The present invention relates to the field of silica gel production, and in particular to a highly efficient, energy-saving production waste heat recovery and utilization system and process thereof, as well as a method for mass-producing silica gel. [Background technology]

[0002] Silica gel is a silica xerogel with a three-dimensional network structure, a porous material with a wide distribution range of pores and a large specific surface area, and its surface is covered with many silanol groups, giving it a certain level of activity. Due to these 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 medicine, electronics, cosmetics, and food processing.

[0003] In the silica gel manufacturing process, silica gel is produced by the sol-gel method using sodium silicate and sulfuric acid as the main raw materials, and then the silica gel is aged, cut, washed, and dried to obtain the finished silica gel. The products produced throughout the manufacturing process include not only the finished silica gel, but also wet silica gel scraps, dry silica gel scraps, sodium sulfate salt water, and wastewater. Currently, the disposal methods for wet silica gel scraps and dry silica gel scraps are to process them as scrap or sell them at low prices. Because the recovery cost of sodium sulfate salt water is relatively high due to its concentration and processing cost, and the value of the recovered material is not high, it is inevitably discharged as wastewater to a sewage treatment plant for treatment. The generated wastewater, such as washing water and condensate, is also discharged directly to a sewage treatment plant as sewage for treatment. China Patent No. 201210121870.5 discloses a method for preparing silica gel, which uses NaHCO3 or NH4HCO3 as raw material, reacts with sodium silicate Na2O·nSiO2 to produce SiO2 hydrogel, and then obtains silica gel through molding, aging and drying processes. In this method, the recovered washing liquid (or filtrate, etc.) mainly contains Na2CO3 (or also contains NH3·H2O), so the reaction raw material can be re-obtained by introducing CO2 to react, and therefore, except for the silicon source, all other chemicals 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 the generation of wastewater containing acids and salts and environmental pollution can be solved. However, the technical solution of the patent is only theoretically feasible. On the one hand, the cost is very high because carbon dioxide is added to the wastewater, and on the other hand, the technology of this patent only has a theoretically feasible raw material consumption and product yield at the laboratory stage, and the weak acid reaction effect is poor, so it cannot meet the needs of mass production of silica gel.

[0004] Sodium silicate is solid sodium silicate, its molecular formula is Na2O·nSiO2, n is the elastic modulus, which refers to the molar ratio of SiO2 to Na2O, generally 1.5-3.5. The larger the elastic modulus of solid sodium silicate, the more difficult it is to dissolve in water. When n is 1, it can be dissolved in water at room temperature, but when n is larger, hot water is required to dissolve it, and when n is greater than 3, steam above 4 atmospheres is required to dissolve it. The larger the elastic modulus of sodium silicate, the higher the silicon oxide 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 most upstream product in the industrial chain, and is often used as a basic chemical raw material for producing other downstream products, and is also an important raw material for producing silica gel.

[0005] There are two types of manufacturing methods for sodium silicate: dry manufacturing and wet manufacturing. Dry manufacturing methods include the soda ash method and the sodium sulfate method. The soda ash method is a method in which quartz sand and soda ash are mixed in a certain ratio and heated to about 1400°C in a reverberatory furnace to produce molten sodium silicate. Wet manufacturing methods include the caustic soda method, which uses quartz sand (powder) and caustic soda as raw materials and reacts them with steam at 0.6 to 1.0 MPa in an autoclave to directly produce liquid sodium silicate. Among the above manufacturing methods, the soda ash method is the most common in the prior art, but this soda ash method emits more than 137 kilograms of CO2 per ton of product, which has a negative impact on the ecological environment. In manufacturing sodium silicate, the sodium sulfate method is preferred by companies because it is less expensive than the soda ash method and the caustic soda method, but this method also has the following problems. First, it causes serious environmental pollution, and existing desulfurization treatments are almost ineffective. For example, when anhydrous sodium sulfate is used to manufacture sodium silicate, a chemical reaction occurs between sodium sulfate and quartz sand during the manufacturing process, generating a large amount of sulfur dioxide gas. In this method, a large amount of SO2 is generated during the manufacturing process, and more than 200 kilograms of SO2 are emitted per ton of product, which is 130 times the amount emitted by the soda ash method, leading to serious environmental pollution. In the prior art, desulfurization treatments such as the alkali absorption method, the catalytic method, and the ammonia water absorption method were attempted, but the desulfurization efficiency was not high, the economic investment and the results were not balanced, and the concentration of sulfur dioxide after treatment greatly exceeded the emission standards, and even if it was neutralized to sulfate or sulfite and discharged, it would result in a waste of resources. Secondly, in the reverberatory furnace equipment for the reaction, the severe acidic atmosphere caused severe corrosion of the firebricks, and the furnace was used for only 4 to 6 months. In addition, due to the constraints of environmental protection laws and regulations, the technical development of the sodium sulfate method was limited, and the technology of manufacturing sodium silicate by the sodium sulfate method has become an abandoned manufacturing technology in the existing technology.

[0006] In the conventional sulfuric acid production process, sulfur or pyrite is burned in an incinerator with oxygen-enriched air, the gas containing sulfur dioxide produced is dedusted, and then an appropriate amount of air is added and the gas is fed into a converter, where the sulfur dioxide is converted into sulfur trioxide by alum catalyst, and finally absorbed with dilute sulfuric acid to produce sulfuric acid. However, the oxygen-enriched air required for the production process is supplied by an air separation unit. Chinese Patent No. CN202010888165.2 discloses a method and apparatus for producing sodium silicate and sulfuric acid from high sulfur content salt, in which sulfur-containing industrial salt and silicon dioxide are burned with total oxygen to produce sodium silicate. The sulfur-containing flue gas generated during the production process is subjected to heat exchange, dedusting, conversion and absorption to produce sulfuric acid, but the production scenario of the technical solution of the patent requires the use of oxygen-enriched air supplied from an air separation unit to realize continuous and steady production of acid, but such a design increases the production input cost.

[0007] Furthermore, the waste heat generated during the production of sodium silicate and the waste heat generated during the production of silica gel are extremely valuable thermal resources, and no waste heat recovery system specialized for the production of sodium silicate or silica gel has existed in the prior art. Therefore, the prior art needs to be addressed as soon as possible. Summary of the Invention [Problem to be solved by the invention]

[0008] The purpose of the present invention is to provide a system and process for recovering and utilizing waste heat in manufacturing and energy-saving manufacturing, and a method for mass-producing silica gel, in order to overcome the shortcomings of the prior art. In view of the above problems, the present invention proposes a system and process for recovering and utilizing waste heat in manufacturing and energy-saving manufacturing, and a method for mass-producing silica gel, in which the process for producing silica gel forms an environmentally friendly circulation, does not discharge waste air, wastewater, and solid waste, realizes the circulation of sulfur, sodium, and silicon elements, and also realizes the circulation of water and heat resources, achieves high efficiency and energy saving, and is suitable for industrial mass production. [Means for solving the problem]

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

[0010] A highly efficient, energy-saving manufacturing waste heat recovery and utilization system, comprising a moisture waste heat recovery module that recovers and utilizes the thermal energy of heat and moisture generated in the process of drying a material, the moisture waste heat recovery module comprising a conveyor for placing the material, a dryer, a compressor and / or a heat exchanger, the conveyor passes through a number of dryers in sequence, the dryers 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 the material.

[0011] In the above-mentioned 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 passes through the first dryer, the second dryer, and the third dryer in sequence, the preheating conveyor, the first dryer, and the second dryer are each connected to the first compressor via piping, and the second dryer and the third dryer are each connected to the first heat exchanger via piping.

[0012] The above-mentioned highly efficient and energy-saving manufacturing waste heat recovery and utilization system further includes a flue gas waste heat recovery module for recovering and utilizing thermal energy of high-temperature flue gas generated in the manufacturing process, the flue gas waste heat recovery module including 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 which generate high-temperature flue gas, the outlet end of the waste heat boiler is connected to a medium-temperature flue gas inlet end of the second heat exchanger, the high-temperature air outlet end of the second heat exchanger is connected to the reverberatory furnace and the sulfur combustion furnace, respectively, the flue gas outlet end of the second heat exchanger is connected to a first heat pump, the first heat pump is connected to external room 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] The above-mentioned high-efficiency, energy-saving manufacturing waste heat recovery and utilization system further includes a first wastewater waste heat recovery module that recovers and utilizes thermal energy generated in the process of preparing raw materials, and the first wastewater waste heat recovery module includes a cooler, through which tap water or wastewater from the salt recovery treatment device flows to be heated and then flows into the water washing device.

[0014] The above-mentioned high-efficiency, energy-saving manufacturing waste heat recovery and utilization system further includes a second wastewater waste heat recovery module that recovers and utilizes thermal energy generated in the salt recovery and treatment process, the second wastewater waste heat recovery module including a second heat pump and a mixing heater, the second heat pump being connected to a water washing device via a pipe, and the water washing device being connected to the mixing heater via a pipe.

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

[0016] Based on the same technical idea, the present invention provides a highly efficient and 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, and 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 by the conveyor, and drying the wet material in the plurality of dryers to obtain a dry material, The conveyor and the 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 the heat exchanger is recycled to dry the material.

[0017] The process further includes a flue gas heat recovery and utilization step, in which 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, the generated medium-temperature flue gas is introduced into a 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 which is used to heat tap water for the water washing step, and another part is used to heat room 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, low-temperature flue gas is generated on the one hand and introduced into the first heat pump to be further cooled to low-temperature flue gas, and high-temperature air is generated on the other hand and used to support the combustion of the reverberatory furnace and the sulfur combustion furnace.

[0018] The method further includes a heat recovery and utilization step of the first wastewater, in which thermal energy generated by diluting the concentrated sulfuric acid and melting the sodium silicate is recovered in a cooler and used to heat tap water and frozen crystallized water for use in the water washing step.

[0019] The method further includes a second wastewater heat recovery and utilization step of causing the sodium sulfate salt water produced in the water-washing step to flow into a second heat pump, and further recovering the thermal energy of the wastewater discharged in the water-washing step by means of the second heat pump.

[0020] The method further includes a third wastewater heat recovery process for collecting condensed water generated in the first dryer and the second dryer and using the collected condensed water for a water washing process or heating.

[0021] Based on the same technical idea, the present invention provides a method for mass-producing silica gel, which comprises using the above-mentioned high-efficiency, energy-saving production waste heat recovery and utilization process, and the method for mass-producing silica gel includes: 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: Add sulfur, supplement with an appropriate amount of air, burn it, make the sulfur dioxide in the flue gas a certain concentration, then enter the acid washing section, purify, dry, enter the converter, convert it into sulfur trioxide through catalytic conversion, and finally absorb it with concentrated sulfuric acid to obtain industrial sulfuric acid; The method includes preparing a solution using the sodium silicate produced in step S1 and the sulfuric acid obtained in step S2, gelling, aging, cutting, washing with water, and drying to produce dried silica gel, and then recovering and utilizing the thermal energy of the heat and moisture in the process of drying the silica gel using the above-mentioned production waste heat recovery and utilization system, and recycling it for drying materials in step S3. Furthermore, in the water-washing process, the above-mentioned production waste heat recovery and utilization system can be used to recover and utilize the thermal energy of the flue gas and recycle it for heating the wash water, the heated water becomes steam and is reused, and the heated air is provided to support the combustion of the reverberatory furnace and the sulfur combustion furnace. Furthermore, in the water-washing process, the above-mentioned production waste heat recovery and utilization system can be used to recover and utilize the heat of the first wastewater and recycle the thermal energy for heating the wash water. Furthermore, in the water-washing process, the above-mentioned production waste heat recovery and utilization system can be used to recover and utilize the heat of the second wastewater and recycle the thermal energy for heating the wash water or use it for heating water for heating. Furthermore, in the water-washing process, the above-mentioned production waste heat recovery and utilization system can be used to recover and utilize the heat of the third wastewater and recycle the thermal energy for heating the wash water or use it for heating water for heating.

[0022] In the above-mentioned method for mass-producing silica gel, the silicon source in the 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, (a3) ​​wet silica gel scraps produced in the step of aging and cutting, (a4) alkaline mud precipitated by filtration during the preparation of a solution using sodium silicate, and (a5) polysilicon slag.

[0023] In the above-mentioned method for mass-producing silica gel, the sodium salt in the step S1 is any one selected from the group consisting of (b1) sodium sulfate decahydrate obtained after desalting the sodium sulfate salt water produced in the water-washing step, (b2) anhydrous sodium sulfate obtained after desalting the sodium sulfate salt water produced in the water-washing step, (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 a step of producing sodium silicate.

[0024] In the above-mentioned method for mass-producing silica gel, the water used in the water-washing step in the S3 step is one or more 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, (c3) condensed water generated in the sulfur combustion furnace and the waste heat boiler, (c4) temperature-reduced water generated in the sulfur combustion furnace and the waste heat boiler in the S1 step, (c5) cooling water generated in the step of preparing a solution using sulfuric acid, and (c6) aged water generated in the steps of aging and cutting.

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

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. In the highly efficient and energy-saving manufacturing waste heat recovery and utilization system of the present invention, the heat and moisture in the process of drying silica gel is returned to the dryer or preheating conveyor after being treated, and is reused for drying silica gel, thus realizing the recycling of heat resources and achieving highly efficient energy saving. 2. The highly efficient and energy-saving manufacturing waste heat recovery and utilization system of the present invention further includes a flue gas waste heat recovery module, which recovers the thermal energy of the high-temperature flue gas generated in the reverberatory furnace and the sulfur combustion furnace, and uses it to heat water to steam for use in heating air and water, thereby utilizing the thermal resources of the flue gas, reducing energy consumption and lowering costs. 3. The highly efficient and energy-saving manufacturing waste heat recovery and utilization system of the present invention further includes a first wastewater waste heat recovery module for recovering and utilizing the thermal energy generated in the process of preparing raw materials, which cools the high-temperature liquid sodium silicate to a low temperature and uses the thermal energy to heat tap water or frozen water, and cools the high-temperature diluted sulfuric acid to a low temperature and uses the thermal energy to heat tap water or frozen water, thereby utilizing the thermal resources generated in the process of preparing raw materials, and by recovering the thermal energy, it is possible to avoid the temperature in the gelation process being too high, and to avoid uneven reaction. 4. The highly efficient, 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 thermal energy generated in the salt recovery and treatment process. This module treats the water generated in the salt recovery and treatment process and uses it for washing, and further recovers and utilizes the thermal energy of the wastewater discharged in the washing process, thereby saving heat resources and reducing costs. 5. The highly efficient and energy-saving manufacturing waste heat recovery and utilization system according to the present invention further includes a third wastewater waste heat recovery module for recovering and utilizing the thermal energy generated in the process of drying silica gel, and this module recovers and utilizes the condensed water generated by the dryer, thereby saving heat resources. 6. The highly efficient and energy-saving manufacturing waste heat recovery and utilization process of the present invention can reduce energy consumption throughout the entire process, generate steam at various temperatures, and has a wide range of applications. 7. The method for mass-producing silica gel according to the present invention recovers and utilizes silicon, sodium, sulfur, and water, recovers waste heat and waste air as much as possible, reduces the discharge of waste air and waste water, achieves zero carbon and sulfur emissions, protects the environment, realizes the circulation of materials and energy throughout the production process, reduces energy consumption, cuts production costs, and is suitable for mass production of silica gel. [Brief description of the drawings]

[0027] In order 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 they can obtain other drawings based on these drawings without any creative efforts. [Figure 1] FIG. 2 is a schematic diagram showing the flow of a moisture waste heat recovery module according to the present invention. [Diagram 2] FIG. 2 is a flow diagram of the flue gas waste heat recovery module according to the present invention. [Diagram 3] FIG. 2 is a schematic diagram showing the flow of a first wastewater waste heat recovery module according to the present invention. [Figure 4] FIG. 2 is a flow schematic diagram of a second wastewater waste heat recovery module according to the present invention. [Diagram 5] FIG. 2 is a schematic diagram showing the flow of the third wastewater waste heat recovery module according to the present invention. [Figure 6] FIG. 1 is a schematic diagram showing the flow of a method for mass-producing silica gel according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0029] The highly efficient and energy-saving manufacturing waste heat recovery and utilization system includes a moisture waste heat recovery module that recovers and utilizes the heat energy of heat and moisture generated in the process of drying a material, and the moisture waste heat recovery module 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. In the present invention, the dryer is any of a tray dryer, a conveyor dryer, a drum dryer, a vertical dryer, a mechanical agitator dryer, a rotary dryer, a fluidized bed dryer, a flash dryer, a vibration dryer, a spray dryer, a mesh belt dryer, an air-cooled dryer, etc. The compressor includes, but is not limited to, a piston compressor, a screw compressor, a centrifugal compressor, a linear compressor, a scroll compressor, a roots compressor, etc. The heat exchanger may be any of a jacket heat exchanger, an immersed coil heat exchanger, a spray heat exchanger, a jacket heat exchanger, a plate heat exchanger, a shell and tube heat exchanger, a double tube plate heat exchanger, a hybrid heat exchanger, a regenerative heat exchanger, a fluid connection indirect heat exchanger, a gas-gas type heat exchanger, a direct contact heat exchanger, a composite heat exchanger, etc. In the present invention, the material is silica gel.

[0030] The waste heat generated in the process of producing sodium silicate and the waste heat from the production of silica gel are very valuable heat resources, but there is no system for recovering waste heat energy specialized in the production of sodium silicate and silica gel in the prior art. In the highly efficient and energy-saving production waste heat recovery and utilization system according to the present invention, the heat and moisture generated in the process of drying silica gel is treated by a compressor, and the medium-low temperature heat and moisture is compressed to generate heat and moisture suitable for drying silica gel, which is recycled for drying silica gel, or the high temperature heat and moisture is treated by a heat exchanger, heat-exchanged with air, to generate heat and moisture suitable for drying silica gel, which is recycled for drying silica gel. In the present invention, the medium-low temperature heat and moisture refers to water vapor with a temperature of 50-100°C and a moisture mass percentage of 0%-100%. The high temperature heat and moisture refers to water vapor with a temperature of over 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 passes through the first dryer, the second dryer, and the third dryer in sequence, the preheating conveyor, the first dryer, and the second dryer are each connected to the first compressor via piping, and the second dryer and the third dryer are each connected to the first heat exchanger via piping.

[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 water vapor 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 and capable of preheating the silica gel while conveying it. In the present invention, the low-temperature wet silica gel is preheated in advance by the preheating conveyor, thereby improving the quality of the product, shortening the drying time, improving the drying effect of the silica gel, and increasing the production amount of the silica gel.

[0033] As shown in FIG. 2, preferably, the method further includes a flue gas waste heat recovery module for recovering and utilizing the thermal energy of the high-temperature flue gas generated in the manufacturing process, the flue gas waste heat recovery module including 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 which generate high-temperature flue gas, where the high-temperature flue gas refers to "flue gas with a temperature of ≧1000° C." The flue gas outlet end of the waste heat boiler is connected to a medium-temperature flue gas inlet end of a second heat exchanger, where the medium-temperature The flue gas refers to "flame gas with a temperature of 230 to 250°C". The high-temperature air outlet end of the second heat exchanger is connected to a reverberatory furnace and a sulfur combustion furnace, respectively, and the high-temperature air here refers to "air with a temperature of 230 to 250°C". The flue gas outlet end of the second heat exchanger is connected to a first heat pump, and the flue gas at the outlet end of the second heat exchanger is 60°C. The heat exchange process is performed by the first heat pump, and low-temperature flue gas is generated by the first heat pump, and the low-temperature flue gas here refers to "flame gas with a temperature of 10 to 35°C". The first heat pump is connected to external room-temperature air and tap water, and the room-temperature air here refers to "air with a temperature of 20 to 25°C". The medium-temperature air outlet end of the first heat pump is connected to a second heat exchanger, and the medium-temperature air here refers to "air with a temperature of 70 to 90°C". Preferably, the second heat exchanger is a gas-gas type heat exchanger. The flue gas waste heat recovery module mainly recovers thermal energy from the flue gas in the sulfur combustion furnace and the reverberatory furnace, and recycles the recovered thermal energy from the flue gas for use in producing sodium silicate, for combustion in the sulfur combustion furnace, for heating water for the water washing device, and for converting heated water into steam.

[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 the waste heat flows into the waste heat boiler for heating or evaporation, and then the second heat exchanger transfers the waste heat to a medium such as air to 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 or sulfur-burning furnace to heat water and use it as steam. The second heat exchanger can transfer energy between two gases with different temperatures, so that the cold gas that flows into the second heat exchanger is heated and 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 for air heating, i.e., heat exchanges the medium-temperature flue gas with the medium-temperature air to generate high-temperature air and flue gas with 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, and is a mechanical device that forcibly flows thermal energy from a low-temperature object to a high-temperature object in a reverse Carnot cycle, and can supply a larger amount of thermal energy by consuming only a small amount of net work in 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 to heat water and air, that is, the flue gas whose temperature has been reduced in the second heat exchanger is further recovered in thermal energy by the first heat pump and becomes low-temperature flue gas, air at room temperature is treated by the first heat pump to become medium-temperature air, and tap water is treated by the first heat pump to become hot water that can be used for washing.

[0035] Preferably, the system further includes a first wastewater waste heat recovery module for recovering and utilizing thermal energy generated in the process of preparing the raw materials, the first wastewater waste heat recovery module including a cooler through which tap water or wastewater from the salt recovery treatment device flows to the water washing device after being heated.

[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 an acid-resistant material, and used to cool a fluid, and generally uses water or air as a coolant to remove thermal energy. In the process of the present invention, the acid cooler cools the 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 an alkali-resistant material, and used to cool a fluid, and generally uses water or air as a coolant to remove thermal energy. In the process of the present invention, the alkali cooler cools the 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 the silica gel. For example, when tap water at room temperature 20° C. is heated by the acid cooler and the alkali cooler, it reaches 35° C., and then is heated to the water washing temperature required for the process and used in the water washing process. The wastewater from freezing and crystallizing salt has a low temperature of 0 to 2°C, but when it is heated in the acid cooler and alkali cooler, it reaches 35°C and is then heated to the water washing temperature required for the process and used in the water washing step.

[0037] Preferably, the second wastewater waste heat recovery module further includes a second heat pump and a mixer heater, the second heat pump is connected to a water washing device through a pipe, the water washing device is connected to the mixer heater through a pipe, the wastewater generated in the water washing device is cooled by the second heat pump and then flows into the salt recovery treatment device, and the high-temperature wastewater from the salt treatment facility, the condensed water generated by drying the silica gel, and the high-temperature steam generated in the residual heat boiler are mixed in the mixer heater and heat exchanged, and then flow into the water washing device. The high-temperature wastewater here refers to "wastewater with a temperature of 40 to 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 salt water generated in the water washing step flows through a second heat pump, and the thermal energy of the wastewater discharged in the water washing step is further recovered by the action of the second heat pump in this process. For example, the wastewater with a temperature of 35-45°C generated in the water washing step becomes water with a temperature of 10-20°C and is used in the membrane concentration step, and 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 step. The wastewater from which the thermal energy has been recovered undergoes membrane concentration desalination treatment, and a desalination treatment method is selected according to the season. In spring, summer, and autumn, the MVR method is adopted, which is an energy-saving technology that reduces the required external energy by reusing the energy of the secondary steam generated by the device itself. In the process of the present invention, in spring, summer, and autumn, the high-concentration salt treatment solution after membrane concentration is evaporated and concentrated by the MVR method, and the water is evaporated to obtain sodium sulfate. In winter, the freeze crystallization method is adopted, and in freeze crystallization, the liquid is supersaturated by lowering the temperature to precipitate crystals, thereby separating the liquid components. In the process of the present invention, in winter, the freeze crystallization method precipitates sodium sulfate in the high-concentration salt treatment solution after membrane concentration as crystals. Preferably, the mixer heater is an air-water mixer heater, which is a heating device that directly mixes steam with water and other liquids, and uses steam to directly heat and raise the temperature of water and other liquids. In the process of the present invention, mixed steam such as low-temperature tap water, pure water, and condensed water is heated to a temperature required for the process, and for example, steam at 160°C is mixed with tap water, pure water, condensed water from MVR, or condensed water from the drying process of wet silica gel by the mixer heater to generate water with a temperature of 45 to 80°C, which is then used for the water washing process.

[0039] Preferably, the system further comprises a third wastewater waste heat recovery module for recovering and utilizing 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, the second dryer also generates condensed water, and the condensed water is collected, 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 highly efficient and 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, and the manufacturing waste heat recovery and utilization process includes a heat and moisture recovery and utilization step of placing a wet material on a conveyor, conveying the wet material through a plurality of dryers in sequence, and drying the material through the plurality of dryers to obtain a dry material, and the dryers are connected to a compressor and / or a heat exchanger via piping, respectively, and the heat and moisture generated in the compressor and / or the heat exchanger are recycled to dry the material. Preferably, the conveyor is a preheating conveyor, and the preheating conveyor is connected to the compressor via piping. Preferably, the material of the present invention is silica gel. Preferably, the wet silica gel is placed on a preheating conveyor and conveyed to a first dryer by the preheating conveyor, and the first dryer dries the silica gel and sends it to a second dryer, and the second dryer further dries the silica gel and sends it to a third dryer, and the third dryer dries the silica gel to produce a dry silica gel. The first compressor compresses the low and medium temperature hot and humid water generated in the preheating conveyor, the first dryer, and the second dryer to produce high temperature hot and humid water. When thermal energy is replenished to the steam, part of this high temperature hot and humid water is sent to the first dryer to dry the silica gel, and the other part is sent to the first heat exchanger. The high temperature hot and humid water sent to the first heat exchanger exchanges heat with the air and is then sent to the second dryer to dry the silica gel. The high temperature hot and humid water generated in the third dryer flows to the preheating conveyor to dry the silica gel.

[0042] The moisture content in the present invention refers to the percentage of the weight of moisture contained in a substance relative to the total weight of the substance. The relative humidity 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, reflecting how far the air is from the 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, the percentage of the mass of water vapor contained in a certain humid air to the mass of water vapor contained in the saturated air at the same temperature and pressure. The water vapor content in the present invention refers to the percentage of the mass of water vapor in the humid air to the total mass of the humid air.

[0043] Referring again to Fig. 1, preferably, the preheating conveyor is for placing wet silica gel with a temperature of 40-60°C and a moisture content of 78%, and the preheating conveyor has a heating effect and performs a certain drying effect on the silica gel, generating medium-low temperature hot and humid air with a temperature of 50-70°C and a relative humidity of more than 90%, which flows into the first compressor, where it is compressed and heated, and the moisture content of the wet silica gel is reduced from 78% to 76%, and then flows into the first dryer. The first dryer is a vertical dryer, and the silica gel moves vertically downward in the first dryer due to its own weight, so that the silica gel is heated by the heating surface it passes through as it falls, and its moisture is evaporated, thereby achieving the purpose of drying the silica gel in the first segment. At the same time, low- to medium-temperature hot and humid air with a temperature of 60-80°C and a water vapor content of 0%-100% is generated, flows into the first compressor, is compressed and heated, and the silica gel with a temperature of 80-100°C and a moisture content of 60% dried in the first dryer flows into the second dryer, which is a drying equipment that continuously dries the silica gel while conveying it using a steel mesh as a conveying belt. The silica gel is evenly spread on the mesh belt by the feeder and moves inside the second dryer while being pulled by a transmission device. The second dryer is composed of multiple units, and hot gas passes through the silica gel laid on the mesh belt from bottom to top or from top to bottom, heating and drying it while removing moisture, and the mesh belt moves slowly, and the operating speed may be adjusted according to the temperature of the silica gel. The dried silica gel falls continuously into a collector, and thus the purpose of drying the silica gel in the second segment is achieved. In this process, low to medium temperature hot and humid air with a temperature of 80-100°C and a relative humidity of over 90% is generated, which flows into the first compressor where it is compressed and heated. The silica gel with a temperature of 120-140°C and a moisture content of 5% dried in the second dryer flows into the third dryer, which uses air at room temperature to lower the temperature of the silica gel while recovering thermal energy. This configuration is useful for subsequent packaging of the dried silica gel product, and thus the purpose of drying the silica gel in the third segment is achieved.In addition, air with a temperature of 20°C and a relative humidity of 70% is supplied to the third dryer, which is an air-cooled dryer, and the hot air with a temperature of 100°C and a relative humidity of 1.6% generated in the third dryer is recycled to the drying of silica gel performed on the preheating conveyor. The above-mentioned low- to medium-temperature hot and humid air with a temperature of 50-70°C and a relative humidity of more than 90% generated in the preheating conveyor, the above-mentioned low- to medium-temperature hot and humid air with a temperature of 60-80°C and a water vapor content of 0%-100% generated in the first dryer, and the low- to medium-temperature hot and humid air with a temperature of 80-100°C and a relative humidity of more than 90% generated in the second dryer flow into the first compressor, where they are compressed and heated, and the generated high-temperature hot and humid air with a temperature of more than 100°C and a water vapor content of 0%-100% exchanges heat with the replenished steam with a temperature of 160°C. In the present invention, the steam with a temperature of 160°C may be supplied from a waste heat boiler. Then, high-temperature hot and humid air with a temperature exceeding 120°C is generated, a part of which is recycled to dry the silica gel in the first dryer, and the other part flows into the first heat exchanger. The high-temperature hot and humid air with a temperature exceeding 120°C that flows into the first heat exchanger exchanges heat with the replenished air at room temperature of 20°C and 70% relative humidity, generating high-temperature hot and humid air with a temperature exceeding 100°C and a relative humidity of less than 2%, which is recycled to dry the silica gel in the second dryer.

[0044] In the flue gas heat recovery and utilization process, high-temperature flue gas is generated in the reverberatory furnace and sulfur combustion furnace and flows into the waste heat boiler, which recovers the thermal energy of the high-temperature flue gas to generate medium-temperature flue gas, which then 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, and part of the thermal energy of the flue gas is used to heat tap water for the water washing process in the water washing device, and the other part is used to heat normal temperature air to medium temperature air, which flows into the second heat exchanger and exchanges heat with the medium temperature flue gas, generating low-temperature flue gas on the one hand, which flows into the first heat pump to further reduce the temperature and become low-temperature flue gas, and generating high-temperature air on the other hand to be used to support the combustion of the reverberatory furnace and sulfur combustion furnace.

[0045] Preferably, high-temperature flue gas with a temperature of about 1000°C is generated in the reverberatory furnace and the sulfur combustion furnace and flows into the waste heat boiler, which recovers the thermal energy of the high-temperature flue gas to generate medium-temperature flue gas with a temperature of 250°C. The medium-temperature flue gas then 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. Part of this thermal energy of the flue gas is used to heat tap water for the water washing process, and the other part is used to heat the room temperature air of 20°C to medium temperature air of 80°C. The medium temperature air of 80°C flows into the second heat exchanger and exchanges heat with the medium temperature flue gas of 250°C. Some of the air is cooled to 60°C as flue gas and flows into the first heat pump where it is further cooled to 15°C as low temperature flue gas. The other part is used to generate high temperature air of 230°C, which is used to assist in the production of sodium silicate in the reverberatory furnace and to assist in the combustion of sulfur added to the sulfur combustion furnace.

[0046] In the first wastewater heat recovery and utilization process, the cooler recovers the thermal energy generated by diluting the wastewater with concentrated sulfuric acid and melting the sodium silicate, and heats tap water or frozen crystallized water to be used in the water washing process.

[0047] Preferably, the cooler includes an acid cooler for diluting concentrated sulfuric acid having a concentration of more than 92.5% to dilute sulfuric acid having a concentration of 20% to 35%, and an alkali cooler for melting solid sodium silicate, and 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 a temperature of 20°C or frozen crystallization water at a temperature of 0 to 2% with thermal energy to water at a temperature of 35°C required for the water-washing step, and the alkali cooler 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 to 2% with thermal energy to water at a temperature of 35°C required for the water-washing step.

[0048] In the second wastewater heat recovery and utilization step, the sodium sulfate salt solution produced in the water-washing step flows through a second heat pump, which further recovers the thermal energy of the wastewater discharged in the water-washing step.

[0049] Preferably, the sodium sulfate salt water generated in the water washing step flows through a second heat pump, which further recovers the thermal energy of the wastewater discharged in the water washing step 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 is subjected to a membrane concentration desalination treatment, and a desalination treatment method is selected according to the season. In spring, summer, and autumn, the MVR method is adopted, in which the high-concentration salt-treated solution after membrane concentration is evaporated to concentrate, and the water is evaporated to obtain sodium sulfate. In winter, the freeze crystallization method is adopted, in which the sodium sulfate in the high-concentration salt-treated solution after membrane concentration is precipitated as crystals. The mixer heater mixes low-temperature tap water, pure water, condensed water, etc. with steam at a temperature of 160°C, heats it to a temperature required for the process, and supplies it to the water washing step. In the present invention, steam having a temperature of 160°C is supplied from a waste heat boiler, and a part of the steam having 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 moist water.

[0050] In the third wastewater heat recovery process, condensed water generated in the first and second dryers is collected and used for the water washing process or heating.

[0051] Preferably, the first dryer generates condensed water at a temperature of 60 to 80°C, and the second dryer generates condensed water at a temperature of 80 to 100°C. The condensed water is collected, a portion of which may be recycled to the water washing step, and another portion may be used for heating.

[0052] 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 largest, accounting for 43.8% of the total amount of thermal energy recovered and utilized, the moisture waste heat recovery module recovers and utilizes the next largest amount of thermal energy, accounting for 40.9% of the total amount of thermal energy recovered and utilized, the second wastewater waste heat recovery module recovers and utilizes the thermal energy, accounting for 6.4% of the total amount of thermal energy recovered and utilized, the third wastewater waste heat recovery module recovers and utilizes the thermal energy, accounting for 6.1% of the total amount of thermal energy recovered and utilized, and the first wastewater waste heat recovery module recovers and utilizes the thermal energy, accounting for 2.8% of the total amount of thermal energy recovered and utilized.

[0053] As shown in FIG. 6, based on the same technical idea, the present invention also provides a method for mass-producing silica gel, comprising using the above-mentioned high-efficiency, energy-saving, production waste heat recovery and utilization process, the method comprising the following steps:

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

[0055] In S2, sulfur is added, and an appropriate amount of air is added for combustion, so that the sulfur dioxide in the flue gas has a certain concentration. Specifically, the flue gas rich in sulfur dioxide in step S1 is fed into a waste heat boiler, sulfur is added to a sulfur combustion furnace, and an appropriate amount of air is added for combustion at about 1000°C. The generated sulfur dioxide flue gas is also fed into the waste heat boiler. After the flue gas from the outlet of the reverberatory furnace and the sulfur combustion furnace is recovered from the waste heat boiler, the temperature of the flue gas is lowered to 230-250°C, and the sulfur dioxide concentration of the flue gas is 5.6% by volume or more. Then, the flue gas enters the acid washing section, where the dust in the flue gas is removed by purification, the flue gas is cooled to below 35°C, and is dried and dehydrated with concentrated sulfuric acid. Then, the flue gas is fed into a converter, where it is converted into sulfur trioxide by a vanadium catalyst. Finally, the concentrated sulfuric acid with a mass percentage of 98% is used to absorb the flue gas in an absorption tower at a temperature of 60°C to obtain industrial sulfuric acid.

[0056] In the prior art, it is necessary to control the concentration of sulfur dioxide to remove it from the exhaust. Desulfurization is performed by alkaline liquid absorption, catalytic method, and ammonia water absorption method, but the desulfurization efficiency is insufficient, the economic investment and the result are not balanced, and the concentration of sulfur dioxide after treatment is far beyond the emission standard. Meanwhile, the present invention adopts a method opposite to that of the prior art, and treats the sulfur dioxide in the exhaust by adding sulfur, while using sulfur to prepare sulfuric acid. The prior art discloses the preparation of sulfuric acid using sulfur dioxide in the exhaust, but in order to ensure the quality of the sulfuric acid produced, the total oxygen combustion type air separation equipment is used, which occupies a large area, is expensive, and the cost of total oxygen combustion is not suitable for practical production, and theoretically cannot be converted into productivity, which is disadvantageous for industrial mass production. In addition, the flue gas is cooled to 230-250°C in order to ensure operational stability when preparing sulfuric acid. If the temperature is too high, exceeding 250°C, a load is applied to the subsequent transport pipelines and sulfuric acid purification equipment. If the temperature is lower than 230°C, sulfurous acid is 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 of the equipment and will also pose a risk to the equipment during operation.

[0057] In S3, a solution is prepared using the sodium silicate produced in step S1 and the sulfuric acid obtained in step S2, and the solution is gelled, aged, cut, washed with water, and dried to produce dried silica gel. In the process of drying the silica gel, the thermal energy of the heat and moisture is recovered and utilized using the above-mentioned manufacturing waste heat recovery and utilization system, and recycled for drying the material.

[0058] Preferably, the method further includes a flue gas heat recovery and utilization step, in which the high-temperature flue gas generated in the reverberatory furnace in step S1 and the sulfur combustion furnace in step S2 is fed into a waste heat boiler, the waste heat boiler recovers the thermal energy of the high-temperature flue gas to generate medium-temperature flue gas, and the medium-temperature flue gas is then fed into a 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 is used to heat tap water for the water washing process, and the other part is used to heat normal temperature air to medium temperature air, which is fed into the second heat exchanger for heat exchange with the medium-temperature flue gas, generating low-temperature flue gas, which is fed into the first heat pump to further cool the flue gas to low temperature, while generating high-temperature air to be used for supporting the combustion of the reverberatory furnace and the sulfur combustion furnace.

[0059] Preferably, the method further includes a step of recovering and utilizing heat from the first wastewater, and the heat energy from diluting with concentrated sulfuric acid and fusing sodium silicate is recovered in a cooler in the gelling step in step S3, and is used to heat tap water and frozen crystallized water for the water washing step.

[0060] Preferably, the method further includes a step of recovering and utilizing heat from the second wastewater, in which the sodium sulfate salt water produced in the water-washing step in step S3 is fed into a second heat pump, and the thermal energy of the wastewater discharged in the water-washing step is further recovered by the second heat pump.

[0061] Preferably, the method further includes a third wastewater heat recovery and utilization step, in which the condensed water generated in the first dryer and the second dryer in the drying step in step S3 is used for a water washing step or heating.

[0062] Preferably, the silicon source in the step S1 is any one selected from the group consisting of (a1) quartz sand, (a2) dried silica gel scraps produced in the step of producing dried silica gel, (a3) ​​wet silica gel scraps produced in the step of aging and cutting, (a4) alkaline mud precipitated by filtration during the preparation of a solution 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 obtained after desalting the sodium sulfate brine produced in the water-washing step, (b2) anhydrous sodium sulfate obtained after desalting the sodium sulfate brine produced in the water-washing step, (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 a step of producing sodium silicate. More preferably, the sodium salt in the S1 step is any one selected from (b1) sodium sulfate decahydrate obtained after desalting the sodium sulfate brine produced in the water-washing step, and (b2) anhydrous sodium sulfate obtained after desalting the sodium sulfate brine produced in the water-washing step.

[0064] Preferably, 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 obtained by condensing steam generated in the silica gel drying step, (c3) condensed water generated in a sulfur combustion furnace or a waste heat boiler, (c4) temperature-reduced water generated in the sulfur combustion furnace or a waste heat boiler in the S1 step, (c5) cooling water generated in a step of preparing a solution using sulfuric acid, and (c6) aging water generated in a step of aging and cutting.

[0065] Preferably, the sulfur-containing fuel in step S1 is high sulfur coal or high sulfur petroleum coke powder. In the prior art, high sulfur coal or high sulfur petroleum coke powder has many problems when used, as follows: Combustion produces SO2 or SO3, which is easily combined with water vapor to produce sulfuric acid vapor, resulting in serious corrosion of combustion equipment, and therefore strict requirements for equipment. When the generated SO2 or SO3 is discharged into the air, it causes serious air pollution. It is easy to spontaneously combust or deteriorate during storage, which affects the combustion effect. Therefore, high sulfur coal or high sulfur petroleum coke powder is rarely used in production due to the above problems. Meanwhile, in the present application, high sulfur coal or high sulfur petroleum coke powder is not only used as fuel, but also provides sulfur element and is applied to improve the concentration of sulfur dioxide for preparing sulfuric acid, and sulfur dioxide does not affect the corrosion of equipment due to temperature restrictions, does not cause environmental pollution due to exhaust, and increases the utilization value of waste resources. Example 1

[0066] This embodiment provides a highly efficient and energy-saving manufacturing waste heat recovery and utilization system, which includes a moisture waste heat recovery module R-4 for recovering and utilizing the thermal energy of heat and moisture generated in the process of drying silica gel.

[0067] As shown in FIG. 1, 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, and the preheating conveyor 1 passes through the first dryer 2, the second dryer 3, and the third dryer 4 in sequence, and the preheating conveyor 1, the first dryer 2, and the second dryer 3 are each connected to the first compressor 5 through a pipe, and the second dryer 3 and the third dryer 4 are each connected to the first heat exchanger 6 through a pipe. In this embodiment, 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 water vapor recompression compressor, and the first heat exchanger 6 is a gas-gas type heat exchanger.

[0068] As shown in FIG. 2, the manufacturing process 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 includes a waste heat boiler 7, a second heat exchanger 8, and a first heat pump 9. The waste heat boiler 7 has a flue gas inlet end connected to a reverberatory furnace 10 and a sulfur combustion furnace 12 that generate high-temperature flue gas, a flue gas outlet end of the waste heat boiler 7 connected to a medium-temperature flue gas inlet end of the second heat exchanger 8, and a high-temperature air outlet end of the second heat exchanger 8 connected to the reverberatory furnace 10 and the sulfur combustion furnace 12, respectively. The medium-temperature flue gas outlet end of the second heat exchanger 8 is connected to a first heat pump 9, and the first heat pump 9 is connected to external room-temperature air and tap water, and 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 type heat exchanger.

[0069] As shown in FIG. 3, the first wastewater waste heat recovery module R-2 is further included, which recovers and utilizes the thermal energy generated in the process of preparing the raw material. The first wastewater waste heat recovery module R-2 includes a cooler, and tap water or wastewater from the salt recovery treatment device flows through the cooler to be heated and then flows into the 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 the 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 the tap water or cooling water with thermal energy. The tap water or cooling water heated in the acid cooler 15 and the alkali cooler 14 is used in the water washing process of the silica gel.

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

[0071] As shown in FIG. 5, the apparatus further includes 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. Example 2

[0072] The present invention provides a highly efficient and energy-saving manufacturing waste heat recovery and utilization process, which uses the manufacturing waste heat recovery and utilization system described in Example 1 to recover and utilize thermal energy, and includes the following hot and humid heat recovery and utilization process, 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] The heat and moisture recovery process includes a heat and moisture recovery process in which the wet silica gel is placed on a conveyor, and the wet silica gel is transported by the conveyor through a plurality of dryers in sequence, and the silica gel is dried by the plurality of dryers to obtain a dry silica gel, and the conveyor and the dryer are connected to a compressor or a heat exchanger via piping, respectively, and the heat and moisture generated in the compressor and / or the heat exchanger is recycled to dry the silica gel. Preferably, the wet silica gel is placed on a preheating conveyor 1 and transported to a first dryer 2 by the preheating conveyor 1, the first dryer 2 dries the silica gel and transports it to a second dryer 3, the second dryer 3 further dries the silica gel and transports it to a third dryer 4, and the third dryer 4 dries the silica gel to produce a dry silica gel. The first compressor 5 compresses the low and medium temperature hot and humid water generated in the preheating conveyor 1, the first dryer 2, the second dryer 3, and the third dryer 4 to produce high temperature hot and humid water. After the heat energy is replenished to the steam, part of this high temperature hot and humid water is sent to the first dryer 2 to be used for drying the silica gel, and the other part is sent to the first heat exchanger 6. The high temperature hot and humid water sent to the first heat exchanger 6 is heat exchanged with the air and then sent to the second dryer 3 to be used for drying the silica gel, and the high temperature hot and humid water generated in the third dryer 4 is sent to the preheating conveyor 1 to be used for drying the silica gel.

[0074] Specifically, the preheating conveyor 1 carries wet silica gel with a temperature of 40-60°C and a moisture content of 78%, and the preheating conveyor 1 has a heating function and performs a certain drying function on the silica gel, generating medium-low temperature heat and moisture with a temperature of 50-70°C and a relative humidity of over 90%, which flows into the first compressor 5 where it is compressed and heated, and the moisture content of the wet silica gel is reduced from 78% to 76%, and then flows into the first dryer 2. The first dryer 2 is a vertical dryer, and the silica gel moves vertically downward in the first dryer 2 due to its own weight, so that the silica gel is heated by the heating surface it passes through as it falls, and its moisture is also vaporized, thereby achieving the purpose of drying the silica gel in the first segment. In addition, low- to medium-temperature hot and humid air with a temperature of 60-80°C and a water vapor content of 0%-100% is generated, flows into the first compressor 5, where it is compressed and heated. The silica gel with a temperature of 80-100°C and a moisture content of 60% that is dried in the first dryer 2 flows into the second dryer 3, which is a drying equipment that continuously dries the silica gel while conveying it using a steel mesh as a conveying 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 is composed of multiple units, and hot gas passes through the silica gel laid on the mesh belt from bottom to top or from top to bottom, heating and drying it while removing moisture, and the mesh belt moves slowly, and the operating speed may be adjusted according to the temperature of the silica gel. The dried silica gel falls continuously into a collector, and thus the purpose of drying the silica gel in the second segment is achieved. In this process, low- to medium-temperature hot and humid air with a temperature of 80-100°C and a relative humidity of over 90% is generated, which flows into the first compressor 5 where it is compressed and heated. The silica gel with a temperature of 120-140°C and a moisture content of 5% dried in the second dryer 3 flows into the third dryer 4, which uses air at room temperature to lower the temperature of the silica gel, recovering thermal energy while lowering the temperature of the silica gel. This configuration is useful for packaging the dried silica gel product afterwards, and thus the purpose of drying the silica gel in the third segment is achieved.In addition, air with a temperature of 20°C and a relative humidity of 70% is supplied to the third dryer 4, which is an air-cooled dryer, and the hot air with a temperature of 100°C and a relative humidity of 1.6% generated in the third dryer 4 is recycled to the drying of silica gel performed on the preheating conveyor 1. The above-mentioned medium-low temperature hot and humid air with a temperature of 50-70°C and a relative humidity of more than 90% generated in the preheating conveyor 1, the above-mentioned medium-low temperature hot and humid air with a temperature of 60-80°C and a water vapor content of 0%-100% generated in the first dryer 2, and the medium-low temperature hot and humid air with a temperature of 80-100°C and a relative humidity of more than 90% generated in the second dryer 2 flow into the first compressor 5, where they are compressed and heated, and the generated high temperature hot and humid air with a temperature of more than 100°C and a water vapor content of 0%-100% exchanges heat with the replenished steam with a temperature of 160°C. In the present invention, the steam with a temperature of 160°C may be supplied from the residual heat boiler 7. Thereafter, high-temperature hot and humid air with a temperature exceeding 120°C is generated, and part of this high-temperature hot and humid air is recycled to dry the 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 that flows into the first heat exchanger 6 exchanges heat with the replenished air at room temperature of 20°C and relative humidity of 70%, generating high-temperature hot and humid air with a temperature exceeding 100°C and a relative humidity of less than 2%, which is recycled to dry the silica gel in the second dryer 3.

[0075] In the flue gas heat recovery and utilization process, high-temperature flue gas at a temperature of approximately 1000°C is generated in the reverberatory furnace 10 and the sulfur combustion furnace 12 and flows into the waste heat boiler 7. The waste heat boiler 7 recovers the thermal energy of the high-temperature flue gas to generate medium-temperature flue gas at a temperature of 250°C. The medium-temperature flue gas then flows into the second heat exchanger 8 where heat exchange takes place. The first heat pump 9 recovers the thermal energy of the flue gas discharged from the second heat exchanger 8. Part of this thermal energy of the flue gas is used to heat tap water for the water washing process, and the other part is used to heat the room temperature air of 20°C to medium temperature air of 80°C. The medium temperature air of 80°C flows into the second heat exchanger 8 and exchanges heat with the medium temperature flue gas of 250°C. Some of the air is cooled to 60°C as flue gas, and flows into the first heat pump 9 where it is further cooled to low temperature flue gas of 15°C. The other part is used to generate high temperature air of 230°C, which is used to support combustion in the reverberatory furnace 10 and the sulfur combustion furnace 12.

[0076] In the first wastewater heat recovery and utilization process, the coolers include an acid cooler 15 for diluting concentrated sulfuric acid with a concentration of over 92.5% to dilute sulfuric acid with a concentration of 20% to 35%, and an alkali cooler 15 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 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 crystallized water at a temperature of 0 to 2% with thermal energy to water at a temperature of 35°C, and then heats it to a process temperature required for the water-washing process for use in the water-washing process. The alkali cooler 14 cools high-temperature liquid sodium silicate to a low temperature, and heats tap water at a temperature of 20°C or frozen crystallized water at a temperature of 0 to 2% with thermal energy to water at a temperature of 35°C, and then heats it to a process temperature required for the water-washing process for use in the water-washing process.

[0077] In the second wastewater heat recovery and utilization process, the sodium sulfate salt water generated in the water washing process flows through the second heat pump 16, which further recovers the thermal energy of the wastewater with a temperature of 35 to 45°C discharged in the water washing process. The wastewater with a temperature of 10 to 20°C from which the thermal energy has been recovered is subjected to membrane concentration desalination treatment, and a desalination treatment method is selected according to the season. In spring, summer, and autumn, the MVR method is adopted, in which the high-concentration salt treatment solution after membrane concentration is evaporated to concentrate, and the water is evaporated to obtain sodium sulfate. In winter, the freeze crystallization method is adopted, in which the sodium sulfate in the high-concentration salt treatment solution after membrane concentration is precipitated as crystals. The mixer heater mixes low-temperature tap water, pure water, condensed water, 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, steam at a temperature of 160°C is supplied from the waste heat boiler 7, and 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 moist water.

[0078] In the third wastewater heat recovery and utilization process, 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. These condensed waters are collected, some of which is recycled to the water washing process of the water washing device 13, and the other part is used for heating.

[0079] When converted into 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 embodiment also provides a method for mass producing silica gel, as shown in FIG. 6, specifically including the following steps:

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

[0082] In step S2, the flue gas rich in sulfur dioxide from step S1 is introduced into the residual heat boiler 7, and a liquid sulfur spray gun is used to spray molten sulfur into the sulfur combustion furnace 12 so as to add 45 kg of sulfur per 1000 cubic meters of flue gas. An appropriate amount of air is then replenished and the flue gas is continued to be burned at about 1000°C. The generated sulfur dioxide flue gas is also introduced into the residual heat boiler 7, and the thermal energy of the high-temperature flue gas at about 1000°C at the outlet of the sulfur combustion furnace 12 and the reverberatory furnace 10 is recovered by the residual heat boiler 7, and the flue gas is cooled to 230-250°C. Preferably, the high-temperature flue gas of about 1000°C is cooled to a medium-temperature flue gas of 250°C, and the sulfur dioxide concentration in the flue gas becomes 5.6% by volume. Then, the flue gas enters the acid washing section to remove dust in the flue gas by purification, and the temperature is reduced to below 35°C by a gas-gas heat exchanger, and the flue gas is cooled to a low temperature of preferably 15°C. The flue gas is dried and dehydrated with concentrated sulfuric acid, and then flows into a converter to be converted to sulfur trioxide by vanadium catalyst. Finally, the flue gas is absorbed in an absorption tower at a temperature of 60°C using concentrated sulfuric acid with a mass percentage of 98%, and industrial sulfuric acid with a concentration of more than 92.5% is obtained, which meets the qualifications 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, and the solution is gelled, aged, cut, washed with water, and dried to produce dried silica gel. Specifically, in the water washing step in the S3 step, the water used in the water washing step is treated wastewater generated in the water washing step.

[0084] The method for mass-producing silica gel according to this embodiment further includes using the highly efficient and energy-saving manufacturing waste heat recovery and utilization process described in embodiment 2, specifically includes: a hot and humid heat recovery and utilization process, a flue gas heat recovery and utilization process, a first wastewater heat recovery and utilization process, a second wastewater heat recovery and utilization process, and a third wastewater heat recovery and utilization process.

[0085] This embodiment produces silica gel that meets the index requirements in the silica gel industry standard HG / T2765.1-2765.6-2005.

[0086] The method for mass-producing silica gel according to the present embodiment forms an environmentally friendly circulation in the process of producing silica gel, does not discharge wastewater, waste gas and solid waste, realizes the circulation of sulfur elements, sodium elements and silicon elements, and also realizes the circulation of water resources and heat resources, achieves efficiency and high-efficiency energy saving, and is suitable for industrial mass production.

[0087] It should be noted that the above is merely a preferred embodiment of the present invention, and that those skilled in the art may make some improvements or modifications without departing from the principles of the present invention. These improvements or modifications should also be considered as part of the scope of protection of the present invention. [Explanation of symbols]

[0088] 1 Preheating conveyor 2 1st dryer 3 Second dryer 4 Third dryer 5. First Compressor 6 1st heat exchanger 7. Waste heat boiler 8 Second heat exchanger 9. First heat pump 10 Reverberatory furnace 11 Water quenching tank 12 Sulfur burning furnace 13 Water washing equipment 14 Alkaline 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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