CN113877937A - Method and system for treating waste salt through microwave thermal desorption and oxidation of rotary kiln - Google Patents
Method and system for treating waste salt through microwave thermal desorption and oxidation of rotary kiln Download PDFInfo
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- CN113877937A CN113877937A CN202111209080.8A CN202111209080A CN113877937A CN 113877937 A CN113877937 A CN 113877937A CN 202111209080 A CN202111209080 A CN 202111209080A CN 113877937 A CN113877937 A CN 113877937A
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- 238000001816 cooling Methods 0.000 claims abstract description 13
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
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- Environmental & Geological Engineering (AREA)
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- General Engineering & Computer Science (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The application discloses a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln, and belongs to the technical field of waste salt treatment. The method for treating the waste salt through microwave thermal desorption and oxidation of the rotary kiln comprises the steps of S1, mixing waste salt to be treated, powder fuel and wave-absorbing medium particles according to a preset proportion to form mixed discharge; s2, performing microwave thermal desorption and oxidation treatment on the mixed discharged material to form a mixed discharged material mixed by pure salt and wave-absorbing medium particles; and S3, screening the mixed material to form oversize products and undersize products, conveying the oversize products back to the S1 step to be used as wave-absorbing medium particles of the mixed material, and simultaneously cooling and collecting the undersize products to form pure salt. The microwave energy consumption for treating the waste salt can be greatly reduced by introducing the powder fuel and the wave-absorbing medium particles, the cost is saved, and the method is suitable for treating large-batch waste salt.
Description
Technical Field
The invention relates to the technical field of industrial waste salt treatment, in particular to a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln.
Background
The industrial waste salt is from multiple fields of soda ash, chlor-alkali, pesticide, pharmacy, fine chemical industry, printing and dyeing, coal chemical industry and the like, and is a general name of the byproduct crystalline salt. The waste salt is usually doped with toxic and harmful organic matters or heavy metals in the crystallization process, and is extremely difficult to treat industrial hazardous waste and solid waste.
The national records of hazardous wastes (2016, 3 months) clearly demarcate distillation and reaction residues (including waste salt) generated in the production process of chemical synthesis raw material medicines, waste mother liquor and reaction base wastes generated in the production process of chemical synthesis raw material medicines into hazardous wastes (including waste salt), and the hazardous wastes must be executed according to corresponding legal and regulatory requirements and must not be discharged privately.
Industrial waste salt yields of more than 1,000 million tons per year, are not properly disposed of in many places, and are considered as hazardous solid wastes that are difficult to landfill and dispose of. At present, a lot of companies temporarily store a large amount of salt slag, and the phenomenon of expansion of the warehouse is commonly occurred.
Since the toxic and harmful organic substances TOC are usually attached and enriched to the industrial waste salt, the industrial waste salt is thermally treated to remove, decompose and oxidize the toxic and harmful organic substances TOC so as to completely convert the toxic and harmful organic substances TOC into CO2And H2O, is the most efficient and one of the most common methods of waste salt treatment.
As shown in attached figure 1, the industrial high-salinity wastewater is firstly concentrated by a membrane to obtain a concentrated solution containing salt with higher concentration. The direct incineration of the concentrated solution not only has high energy consumption, but also the molten waste salt is difficult to be recycled after the incineration. And (3) carrying out Mechanical Vapor Recompression (MVR) technology or multi-effect evaporative crystallization (MEE) technology and crystallization and filter pressing on the concentrated solution to obtain the industrial salt mud containing organic TOC.
At present, three methods for thermal treatment of industrial salt mud containing toxic and harmful organic TOC are mainly used, namely high-temperature melting treatment, high-temperature grading carbonization and cracking treatment, and microwave thermal desorption and oxidation treatment. But the energy consumption of the high-temperature melting treatment of the waste salt is high, and the molten waste salt is carried to downstream condensation and deposition by flue gas, so that downstream equipment is easily blocked and corroded. And the organic carbon particles generated by the pyrolysis and carbonization treatment of the waste salt have low activity, are not easy to burn and remove reversely, and can deposit in the inner hole or the surface of the waste salt to generate secondary pollution. In addition, the pyrolysis carbonization temperature is high, the heating is uneven, the phenomenon of local waste salt fusion bonding is severe easily caused, the surface of equipment is corroded, and the equipment is damaged in severe cases.
Chinese patents CN104344407A, CN106801874A, CN110404943A, CN107098363A, CN107892928A, etc. disclose methods for treating industrial waste salt by microwave desorption, cracking or oxidation, wherein CN104344407A discloses a process flow for treating waste salt by microwave, which comprises the steps of mixing waste salt, drying and dehydrating by microwave, and cracking, wherein the cracking temperature is 450-500 ℃, and the cracking time is over 100 min. The microwave treatment of industrial waste salt has the advantages that the microwave can penetrate the waste salt indiscriminately, heat the waste salt quickly and uniformly without causing the surface of the waste salt to be overheated and form rings or slag. But the electric energy is a high-grade energy source, and the cost of the heating energy consumption with the same power is far higher than that of the common fuel. This is the most limited factor for the spread of microwave heating equipment. In addition, the microwave attenuation performance is limited, and the single set of equipment for treating the waste salt by microwave has compact structure and is difficult to amplify, so that the waste salt cannot be treated in large batch.
In conclusion, no method for continuously treating industrial waste salt containing toxic and harmful organic TOC in large scale exists at present. The invention aims to solve the problem and provides a technical scheme for treating large-batch industrial waste salt by microwave thermal desorption and oxidation, which is efficient, energy-saving and free of coking and carbon deposition.
Disclosure of Invention
The invention mainly aims to provide a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln, which can effectively and greatly reduce the microwave energy consumption for treating the waste salt and save the cost by introducing powder fuel and wave-absorbing medium particles.
The invention mainly aims to provide a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln, effectively solves the problem that the microwave heating power is difficult to amplify by introducing powder fuel, and is suitable for treating large-scale industrial waste salt.
The invention mainly aims to provide a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln, wherein the thermal desorption or oxidation reaction rate can be well adjusted by introducing aerobic gas, and the quality of clean salt is improved.
The invention mainly aims to provide a method and a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln.
In order to achieve at least one of the above objects, the present invention provides a method for treating waste salt by microwave thermal desorption and oxidation of a rotary kiln, for treating industrial waste salt, comprising the steps of:
s1, mixing the waste salt to be treated, the powder fuel and the wave-absorbing medium particles according to a preset proportion to form a mixed discharge;
s2, performing microwave thermal desorption and oxidation treatment on the mixed discharged material to form a mixed discharged material mixed by pure salt and wave-absorbing medium particles; and
and S3, screening the mixed material to form oversize products and undersize products, conveying the oversize products to return to the step S1, using the oversize products as wave-absorbing medium particles of the mixed material, and cooling and collecting the undersize products to form pure salt.
Preferably, the predetermined ratio among the waste salt to be treated, the powdered fuel and the wave-absorbing medium particles is 1-20: 1: 0.1 to 0.5.
Preferably, the powder fuel is any one or a mixture of sawdust, straw powder and coal powder, so that heat is released and provided when the powder fuel is combusted, and energy consumption required by microwave thermal desorption and oxidation treatment is effectively reduced.
Preferably, the temperature of the microwave thermal desorption and oxidation treatment is 200-700 ℃, so that the temperature of the microwave thermal desorption and oxidation treatment is controlled to be above the volatilization temperature of the organic TOC attached to the waste salt, and is below the melting temperature of the waste salt, thereby ensuring the volatilization of the organic TOC on the surface of the waste salt without melting the waste salt.
Preferably, the method for treating waste salt through microwave thermal desorption and oxidation of the rotary kiln further comprises a step S2-1 of feeding oxygen gas into the rotary kiln to blow waste salt accumulated at the bottom of the rotary kiln in the microwave thermal desorption and oxidation treatment process, so as to stir the waste salt, fully mix the waste salt to be treated, the powder fuel and the wave-absorbing medium particles, avoid possible local overheating and fusion ring formation, and simultaneously desorb organic matters on the surface of the waste salt.
Further, the oxygen-containing gas fed into the rotary kiln is a mixture of any one or more of air, oxygen and steam.
The invention also provides a system for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln, which is used for treating industrial waste salt and comprises:
the mixing unit comprises a powder mixer, and is used for mixing waste salt to be treated, powder fuel and wave-absorbing medium particles in a preset ratio to form mixed discharge;
the conveying unit is used for metering and conveying the mixed discharging material;
the microwave thermal desorption and oxidation treatment unit comprises a rotary kiln, the rotary kiln comprises a rotary kiln body, a spiral conveying shaft and a plurality of microwave hood heads, the spiral conveying shaft is rotatably arranged in the rotary kiln body along the length direction of the rotary kiln body so as to rotatably convey the mixed material conveyed by the conveying unit to the kiln tail of the rotary kiln body, and the plurality of microwave hood heads are arranged in the rotary kiln body along the length direction of the rotary kiln body so as to heat and ignite the powder fuel in the rotary kiln body; and
the device comprises a pure salt processing unit, wherein the pure salt processing unit comprises a screening mechanism, a particle recycling and conveying mechanism and a cooling and collecting mechanism, the screening mechanism is connected to the bottom of the kiln tail to receive and screen mixed discharge formed after being processed by the microwave thermal desorption and oxidation processing unit, the particle recycling and conveying mechanism is connected between the screening mechanism and the powder mixer to convey oversize materials screened by the screening mechanism to the powder mixer to serve as wave-absorbing medium particles of the mixed discharge, and the cooling and collecting mechanism is connected with the screening mechanism to cool and collect undersize materials screened by the screening mechanism to obtain the pure salt.
Preferably, the spiral conveying shaft is provided with a shaft cavity along the axial direction, and a plurality of air outlets communicated with the shaft cavity are distributed on the wall of the spiral conveying shaft along the axial direction;
the system also comprises an air inlet unit, wherein the air inlet unit comprises a blowing element and an air inlet pipeline, one end of the air inlet pipeline is communicated with the shaft cavity of the spiral conveying shaft, the other end of the air inlet pipeline is communicated with the blowing element, and aerobic gas is fed into the shaft cavity and the air outlet of the spiral conveying shaft through the air inlet pipeline.
Preferably, this system still includes the flue gas processing unit, wherein the flue gas processing unit includes draught fan and exhaust pipe, wherein one of them one end opening intercommunication of exhaust pipe the top of kiln head, another end opening intercommunication chimney, the draught fan set up in exhaust pipe, in order to absorb this internal flue gas of rotary kiln extremely the chimney is discharged.
Preferably, the cooling and collecting mechanism comprises a roller slag cooler and a clean salt collecting tank, wherein a slag inlet of the roller slag cooler is positioned below an outlet of the screening mechanism, and the clean salt collecting tank is positioned below a slag outlet of the roller slag cooler.
These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description.
Drawings
Fig. 1 shows a schematic diagram of a conventional treatment process of salt-containing wastewater.
Fig. 2 shows a schematic diagram of a system for treating waste salt by microwave thermal desorption and oxidation of a rotary kiln according to a preferred embodiment of the present application.
Detailed Description
The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.
It will be understood by those skilled in the art that in the disclosure of the specification, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, which are merely for convenience in describing the invention and to simplify the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus the terms are not to be construed as limiting the invention.
In the following description, referring to fig. 2, a method for treating waste salt by rotary kiln microwave thermal desorption and oxidation according to a preferred embodiment of the present invention is used for treating industrial waste salt, and the method comprises the following steps of S1 mixing, S2 waste salt treatment and S3 pure salt treatment.
In step S1, mixing the waste salt to be treated, the powdered fuel, and the wave-absorbing medium particles in a predetermined ratio by a powder mixer to form a mixed discharge, wherein the predetermined ratio among the waste salt to be treated, the powdered fuel, and the wave-absorbing medium particles is 1-20: 1: 0.1-0.5, wherein the preferable preset proportion among the waste salt to be treated, the powdery fuel and the wave-absorbing medium particles is 1-10: 1: 0.2 to 0.5.
It is worth mentioning that the powder fuel is any one or mixture of sawdust, straw powder and coal powder, so as to release heat and provide heat during combustion, thereby effectively reducing energy consumption required by microwave thermal desorption and oxidation treatment. The particle size of the waste salt and the powder fuel to be treated is controlled below 1mm, and the particle size of the wave-absorbing medium particles is controlled between 2mm and 3 mm. In addition, the bulk density of the pulverized fuel is preferably close to that of the waste salt to be treated.
Specifically, the method aims at the treatment of NaCl waste salt from a certain pesticide factory, wherein the dry-basis waste salt and attached TOC components are as follows:
the particle size of the waste salt is 0.5 mm-1.0 mm, and the water content of the waste salt is 0.5%.
The powder fuel is single sawdust with ignition point of 210-230 deg.c and grain size of 0.5-1.0 mm;
the wave-absorbing medium particles are zirconia ceramic balls with the particle size of 2-3 mm.
The mass ratio of the ingredients of the three is as follows: saw dust: 5: 1: 0.5, the feeding amount of the waste salt is 10kg/hr, and the corresponding dosage amounts of the sawdust and the wave-absorbing medium are 2kg/hr and 1kg/hr respectively.
In the step S2 waste salt treatment, specifically, the mixed discharge material mixed in the powder mixer falls to a hopper, the mixed discharge material is conveyed to a rotary kiln through a single-end fixed cantilever screw feeder, and microwave thermal desorption and oxidation treatment are performed in the rotary kiln to form a mixed discharge material in which pure salt and wave-absorbing medium particles are mixed.
It is worth mentioning that the temperature for microwave thermal desorption and oxidation treatment in the rotary kiln is 200-700 ℃, preferably 300-600 ℃, so that the temperature for microwave thermal desorption and oxidation treatment is controlled above the volatilization temperature of the organic TOC attached to the waste salt and below the melting temperature of the waste salt to ensure the volatilization of the organic TOC on the surface of the waste salt without melting the waste salt.
It is worth mentioning that in the microwave thermal desorption and oxidation treatment process of the conventional rotary kiln, as mentioned in the background of the present application, the microwave is generally used to perform indiscriminate waste salt penetration for rapid and uniform heating, which is limited by the microwave attenuation performance, a plurality of microwave hood heads are required to be densely arranged for centralized heating treatment, so that firstly, the structure is compact, the effective amplification is difficult, the waste salt is difficult to be intensively treated in large batch, secondly, the heating power consumption cost is increased in proportion, and the general enterprises cannot bear the treatment cost. In the application, powder fuel and wave-absorbing medium particles are introduced as ingredients of waste salt to be treated, when microwave thermal desorption and oxidation treatment are carried out in the rotary kiln, because the heat release of the pulverized fuel is enough for the temperature rise of the waste salt and the volatilization of organic TOC on the surface of the waste salt, meanwhile, the microwave absorbing medium particles can effectively enhance the microwave absorbing capacity of the waste salt, so that the conventional microwave hood heads which need to be densely configured are only used for heating and igniting the powdery fuel, assisting in heating the waste salt and controlling the temperature in the reaction, the number of the microwave hood heads can be effectively reduced, the installation positions of the microwave hood heads can be reasonably distributed, thereby not only greatly reducing the required number of the microwave cover heads and the equipment cost, meanwhile, the electric energy resource can be effectively saved, the national call for energy conservation and consumption reduction is responded, and thirdly, the application is not limited by the structure and can treat the waste salt in large batch.
Therefore, the method for treating the waste salt through microwave thermal desorption and oxidation of the rotary kiln has very wide applicability, is suitable for treating the waste salt by any large, medium and small enterprises, and can effectively save resources and improve the global environment.
In step S3, the mixed output is received and screened by a vibrating screen to form an oversize and an undersize. The sieve size was 1 mm. As the particle size (2 mm-3 mm) of the wave-absorbing medium particles is far larger than that of the pure salt (less than 1mm), the oversize product formed by screening is the wave-absorbing medium particles, and the undersize product formed is the pure salt. The oversize materials are conveyed pneumatically and returned to the S1 material mixing step to be used as wave-absorbing medium particles for mixed discharging, so that the wave-absorbing medium particles are recycled in the method, raw materials are saved, and the cost is saved; and cooling and collecting the undersize through a roller slag cooler to form pure salt. The detection shows that the TOC content of the organic matters remained on the purified salt is less than 100ppm, and the requirement of resource utilization of the waste salt is completely met.
In addition, the flue gas generated by the microwave thermal desorption and oxidation treatment is purified and then discharged through a draught fan and a chimney.
Therefore, after the waste salt to be treated is subjected to ingredient mixing, microwave thermal desorption and oxidation treatment, organic TOC on the surface of the waste salt is volatilized to form flue gas, the flue gas is discharged after being purified, and the rest of the waste salt is purified salt, cooled and collected.
As a preferred embodiment of the present application, the method for treating waste salt by microwave thermal desorption and oxidation of a rotary kiln further comprises step S2-1, feeding an aerobic gas into the rotary kiln by air distribution, so that the aerobic gas blows the waste salt accumulated at the bottom of the rotary kiln during the microwave thermal desorption and oxidation treatment, thereby stirring the waste salt, and the waste salt to be treated, the powdered fuel and the wave-absorbing medium particles are fully mixed, thereby avoiding the occurrence of possible local overheating and ring formation; meanwhile, the reaction rate of microwave thermal desorption and oxidation treatment can be effectively adjusted, and the quality of the purified salt is improved.
It is worth mentioning that the oxygen gas fed into the rotary kiln is any one or a mixture of air, oxygen and steam.
The embodiment only introduces 300Nm of air through the blower for saving cost and facilitating operation3And/hr. Obviously, as can be understood by those skilled in the art, in order to accelerate the speed of the microwave thermal desorption and oxidation treatment, oxygen or a mixture of air and oxygen may be introduced to accelerate the combustion speed of the pulverized fuel.
In addition, considering that organic TOC may have a certain carbon precipitation reaction in a high-temperature environment, which increases the difficulty of microwave thermal desorption and oxidation treatment of waste salt, and simultaneously, the carbon precipitation causes the pure salt to be blackened, which affects the quality of the pure salt, and the aerobic gas fed into the rotary kiln may also be set as steam or a mixed gas of air, oxygen and steam. The carbon precipitation reaction of organic TOC can be effectively reduced through the moisture in the steam.
Of course, the temperature at which the microwave thermal desorption and oxidation treatment is carried out in the rotary kiln is controlled regardless of the composition of the gas to be fed and regardless of the amount of gas to be fed. As mentioned above, the controlled temperature is preferably between 300 ℃ and 600 ℃.
The invention also provides a system for treating the waste salt through microwave thermal desorption and oxidation of the rotary kiln, which is used for treating the industrial waste salt.
The mixing unit comprises a powder mixer. Mixing the waste salt to be treated, the powdered fuel and the wave-absorbing medium particles according to a predetermined ratio by the powder mixer to form a mixed material, wherein the predetermined ratio is the waste salt to be treated: powder fuel: 1-20% of wave-absorbing medium particles: 1: 0.1-0.5, preferably selecting waste salt to be treated: powder fuel: 1-10% of wave-absorbing medium particles: 1: 0.2 to 0.5.
The conveying unit is used for metering and conveying the mixed discharge. Specifically, the conveying unit comprises a single-end fixed cantilever screw feeder. After the powder mixer is mixed to form mixed discharge, the mixed discharge falls through the hopper and is conveyed to the screw feeder, and then is conveyed to the microwave thermal desorption and oxidation treatment unit in a screw mode.
The microwave thermal desorption and oxidation treatment unit comprises a rotary kiln. The rotary kiln comprises a rotary kiln body, a spiral conveying shaft and a preset number of microwave hood heads. The conveying unit is close to the kiln head of the rotary kiln body, and is partially inserted into the rotary kiln body. The spiral conveying shaft is rotatably arranged in the rotary kiln body along the length direction of the rotary kiln body so as to convey the mixed material conveyed by the conveying unit to the kiln tail of the rotary kiln body in a rotating manner. The microwave hood heads are arranged on the rotary kiln body in a preset number along the length direction of the rotary kiln body so as to heat and ignite the pulverized fuel in the rotary kiln body.
It is worth mentioning that the heat release of the powder fuel in the powder mixer is enough for the temperature rise of the waste salt and the volatilization of organic TOC on the surface of the waste salt, and meanwhile, the wave-absorbing medium particles can effectively enhance the microwave absorption capacity of the waste salt. Therefore, compared with the prior art, the number of the microwave hood heads can be greatly reduced, electric energy resources can be effectively saved, equipment cost is saved, batch treatment of waste salt through the rotary kiln and the microwave hood heads is possible, and the microwave hood heads have wide applicability. For the reasons, the number of the microwave hood heads is set to be 2-5, preferably 3 according to the content of the organic waste salt, the heating power of a single microwave hood head and the temperature control requirement, so that the temperature and the temperature control which completely meet the waste salt treatment can be provided.
It should be noted that the rotary kiln body is arranged obliquely, wherein one end close to the kiln head of the rotary kiln is slightly higher than one end close to the kiln tail. Therefore, the waste salt can gradually move towards the kiln tail under the action of gravity, and the conveying of the spiral conveying shaft is facilitated.
The pure salt processing unit comprises a screening mechanism, a particle recycling and conveying mechanism and a cooling and collecting mechanism, wherein the screening mechanism is preferably a vibrating screen and is connected to the bottom of the kiln tail to receive and screen mixed discharge materials formed after the mixed discharge materials are processed by the microwave thermal desorption and oxidation processing unit, the screening particle size of the vibrating screen is 1mm, oversize materials are wave-absorbing medium particles (the particle size is 2 mm-3 mm) with the particle size larger than 1mm, and undersize materials are pure salt (the particle size is 0.5 mm-1 mm). The particle recovery and conveying mechanism is connected between the screening mechanism and the powder mixer so as to convey oversize materials screened by the screening mechanism to the powder mixer, the oversize materials are used as wave-absorbing medium particles for mixed discharging, and the conveying mode is preferably pneumatic conveying. The wave-absorbing medium particles are pneumatically conveyed for the mixed discharge to be proportioned for recycling, so that the using amount of the wave-absorbing medium particles can be effectively saved in the waste salt treatment process, and the cost is reduced. The cooling and collecting mechanism is connected with the screening mechanism to cool and collect undersize materials screened by the screening mechanism so as to obtain pure salt.
As a preferred embodiment of the present application, the spiral conveying shaft has a shaft cavity along the axial direction, and a plurality of air outlets communicated with the shaft cavity are distributed along the axial direction on the cavity wall of the spiral conveying shaft.
The system for treating waste salt through microwave thermal desorption and oxidation of the rotary kiln further comprises an air inlet unit, and the air inlet unit comprises a blowing element and an air inlet pipeline. The blowing element is preferably a blower. One end of the air inlet pipeline is communicated with the shaft cavity of the spiral conveying shaft, and the other end of the air inlet pipeline is communicated with the blowing element. When the blowing element runs, aerobic gas is fed in through the air inlet pipeline and the shaft cavity and the air outlet of the spiral conveying shaft. The oxygen-containing gas may be any one or a combination of air, oxygen and steam.
As a preferred embodiment of this application, this system still includes flue gas processing unit, wherein flue gas processing unit includes draught fan and exhaust pipe, wherein one of them one end opening intercommunication of exhaust pipe the top of kiln head, another end opening intercommunication chimney. The induced draft fan is set up in smoke exhaust pipe to absorb this internal flue gas of rotary kiln extremely the chimney is discharged.
As a preferred embodiment of the present application, the cooling and collecting mechanism includes a roller slag cooler and a salt purification collecting tank, wherein a slag inlet of the roller slag cooler is located below an outlet of the screening mechanism. The purified salt collecting tank is positioned below a slag outlet of the roller slag cooler. And the undersize materials screened by the screening mechanism directly drop at a slag inlet of the roller slag cooler through an outlet of the screening mechanism. And after the drum slag cooler is cooled, the undersize, namely the purified salt, directly falls into the purified salt collecting tank, and the collection of the purified salt is finished.
In addition, in order to further improve the quality of the pure salt, the pure salt collected by the pure salt collecting tank can be further subjected to air separation treatment so as to remove lighter unburned powdery fuel, and obtain secondary pure salt with better quality.
The aim of air separation is to remove light impurities and dust and also to remove some of the heavier impurities such as stones and clods. The method is commonly used for cleaning oil materials such as cottonseed and sunflower seeds and removing dust and foreign matters in industries such as grain and tobacco. The method is suitable for sorting solid waste with similar particle shape and size. Sometimes, the raw materials can be crushed and screened first and then subjected to wind power sorting.
It will be appreciated by persons skilled in the art that the embodiments of the invention shown in the foregoing description are by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.
Claims (10)
1. The method for treating the waste salt through microwave thermal desorption and oxidation of the rotary kiln is used for treating industrial waste salt and is characterized by comprising the following steps of:
s1, mixing the waste salt to be treated, the powder fuel and the wave-absorbing medium particles according to a preset proportion to form a mixed discharge;
s2, performing microwave thermal desorption and oxidation treatment on the mixed discharged material to form a mixed discharged material mixed by pure salt and wave-absorbing medium particles; and
and S3, screening the mixed material to form oversize products and undersize products, conveying the oversize products to return to the step S1, using the oversize products as wave-absorbing medium particles of the mixed material, and cooling and collecting the undersize products to form pure salt.
2. The method for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln as claimed in claim 1, wherein the predetermined ratio of the waste salt to be treated, the powdered fuel and the wave-absorbing medium particles is 1-20: 1: 0.1 to 0.5.
3. The method for treating waste salt through microwave thermal desorption and oxidation of a rotary kiln as claimed in claim 1, wherein the pulverized fuel is any one or more of sawdust, straw powder and pulverized coal.
4. The method for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in claim 1, wherein the temperature of the microwave thermal desorption and oxidation treatment is 200 ℃ to 700 ℃.
5. The method for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in any one of claims 1 to 4, further comprising a step S2-1 of feeding an oxygen-containing gas into the rotary kiln to blow the waste salt accumulated at the bottom of the rotary kiln during the microwave thermal desorption and oxidation treatment and desorb organic matter on the surface of the waste salt.
6. The method for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in claim 5, wherein the oxygen-containing gas fed into the rotary kiln is a mixture of any one or more of air, oxygen and steam.
7. Through the system of rotary kiln microwave thermal desorption and oxidation treatment waste salt for handle industry waste salt, its characterized in that, this system includes:
the mixing unit comprises a powder mixer, and is used for mixing waste salt to be treated, powder fuel and wave-absorbing medium particles in a preset ratio to form mixed discharge;
the conveying unit is used for metering and conveying the mixed discharging material;
the microwave thermal desorption and oxidation treatment unit comprises a rotary kiln, the rotary kiln comprises a rotary kiln body, a spiral conveying shaft and a plurality of microwave hood heads, the spiral conveying shaft is rotatably arranged in the rotary kiln body along the length direction of the rotary kiln body so as to rotatably convey the mixed material conveyed by the conveying unit to the kiln tail of the rotary kiln body, and the microwave hood heads are arranged in the rotary kiln body along the length direction of the rotary kiln body so as to heat and ignite the powder fuel in the rotary kiln body; and
the device comprises a pure salt processing unit, wherein the pure salt processing unit comprises a screening mechanism, a particle recycling and conveying mechanism and a cooling and collecting mechanism, the screening mechanism is connected to the bottom of the kiln tail to receive and screen mixed discharge formed after being processed by the microwave thermal desorption and oxidation processing unit, the particle recycling and conveying mechanism is connected between the screening mechanism and the powder mixer to convey oversize materials screened by the screening mechanism to the powder mixer to serve as wave-absorbing medium particles of the mixed discharge, and the cooling and collecting mechanism is connected with the screening mechanism to cool and collect undersize materials screened by the screening mechanism to obtain the pure salt.
8. The system for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in claim 7, wherein the spiral conveying shaft is provided with a shaft cavity along the axial direction, and a plurality of air outlets communicated with the shaft cavity are distributed on the wall of the spiral conveying shaft along the axial direction;
the system also comprises an air inlet unit, wherein the air inlet unit comprises a blowing element and an air inlet pipeline, one end of the air inlet pipeline is communicated with the shaft cavity of the spiral conveying shaft, the other end of the air inlet pipeline is communicated with the blowing element, and aerobic gas is fed into the shaft cavity and the air outlet of the spiral conveying shaft through the air inlet pipeline.
9. The system for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in claim 7, further comprising a flue gas treatment unit, wherein the flue gas treatment unit comprises an induced draft fan and a smoke exhaust pipeline, wherein an opening at one end of the smoke exhaust pipeline is communicated with the top of the kiln head, an opening at the other end of the smoke exhaust pipeline is communicated with a chimney, and the induced draft fan is arranged in the smoke exhaust pipeline to suck flue gas in the rotary kiln body to the chimney for discharge.
10. The system for microwave thermal desorption and oxidation treatment of waste salt through a rotary kiln as claimed in claim 7, wherein the cooling collection mechanism comprises a roller slag cooler and a net salt collection tank, wherein the slag inlet of the roller slag cooler is positioned below the outlet of the screening mechanism, and the net salt collection tank is positioned below the slag outlet of the roller slag cooler.
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