CN210522218U - Tail gas treatment system for waste salt resourceful treatment - Google Patents
Tail gas treatment system for waste salt resourceful treatment Download PDFInfo
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- CN210522218U CN210522218U CN201920800239.5U CN201920800239U CN210522218U CN 210522218 U CN210522218 U CN 210522218U CN 201920800239 U CN201920800239 U CN 201920800239U CN 210522218 U CN210522218 U CN 210522218U
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Abstract
The utility model relates to a tail gas processing system is used in waste salt resourceful treatment, tail gas processing system includes two combustion chambers, exhaust-heat boiler, quench tower, sack cleaner, precooler, two-stage scrubbing tower, flue gas white eliminating device, chimney and circulating water groove, two combustion chambers include input and flue gas output, and this two combustion chambers's input includes natural gas input, pyrolysis gas input and aqueous ammonia input, the natural gas input is connected with the natural gas and sets up, can be to the interior input natural gas of second combustion chamber through this natural gas input, the pyrolysis gas input of two combustion chambers is connected with the pyrolysis waste gas of pyrolysis furnace and sets up, the aqueous ammonia input is connected with the aqueous ammonia and sets up, can be to the interior input aqueous ammonia of second combustion chamber through this aqueous ammonia input. The system is simple in structural connection, convenient to use, low in cost, good in effect and capable of completely achieving the emission standard of pollutants in flue gas after pyrolysis waste gas treatment of the pyrolysis furnace, and can be applied to the aspect of waste salt recycling treatment.
Description
Technical Field
The utility model belongs to the technical field of the environmental protection, a tail gas processing system is used in waste salt resourceful treatment is related to.
Background
Industrial waste salt mainly comes from industries such as coal chemical industry, pesticide, chemical fertilizer, biochemical industry and the like, the industrial waste salt cannot be reused in industrial production because a certain amount of organic matters are contained in the industrial waste salt, and the waste salt is classified as dangerous waste by national relevant legal documents. The waste salt is complex in components, high in toxicity and harm, difficult to treat in the hazardous waste industry, extremely high in treatment cost, and the treatment cost of each ton is over 3500 Yuan, so that a great burden is brought to an enterprise, and resource waste is caused.
At present, the technology for treating waste salt at home and abroad is relatively limited, and the main treatment technology comprises the following steps:
(1) direct burning method
The method is that the waste salt slag is directly added to the top of the incinerator, the materials are heated at 900 ℃ from top to bottom, the waste salt is melted and flows into the bottom of the incinerator, the waste salt is cooled and recovered, organic pollutants contained in the waste salt are gasified and decomposed at high temperature, and the tail gas of the incinerator enters a secondary combustion chamber for further combustion or is directly subjected to physical and chemical treatment and then is discharged. However, the method needs to pre-dry the waste salt slag, and requires that the particles of the waste salt slag are uniform and have the particle size as small as possible so as to minimize the temperature gradient inside the particles, but molten salt rain is easily formed at the top of the furnace along with the blast, severe phenomena such as melting, ring formation, agglomeration and the like occur in subsequent units along with the gradual decrease of the temperature, and the molten salt rain is aggregated on the inner wall of a pipeline of equipment, so that the device is easily blocked, and an industrial stabilizing device is not reported yet.
(2) Dissolving impurity removal and evaporation crystallization treatment
The method is to re-dissolve the waste salt in clear water, remove impurities (organic matters, heavy metal ions and the like) by a physical and chemical method, and recover inorganic salt by evaporation crystallization. However, the method has high treatment cost, secondary wastewater and sludge are generated, and particularly, the physical and chemical treatment effects of dissolved salts containing high organic matter concentration are difficult to guarantee.
(3) Harmless landfill disposal
The method is to mix various waste salts and solidify the waste salts by concrete and other curing agents, and then carry out special landfill disposal according to relevant regulations and technical specifications of national hazardous waste management and disposal. The disposal method not only occupies a large amount of land, but also is easy to cause secondary pollution.
(4) Pyrolysis method
The pyrolysis method is to use a pyrolysis furnace to incompletely oxidize organic matters in the waste salt into CH under the anoxic condition at the temperature of 550-600 DEG C4、H2CO and coke. And coke formed after the organic matters in the waste salt are pyrolyzed is remained on the surface of the inorganic salt, and further dissolution, filtration, evaporation and crystallization treatment are required to be carried out, so that the inorganic salt is separated from the coke, and finally, an inorganic salt product with higher purity is prepared.
Therefore, there is a need for one or several related processing devices.
Through searching, the following two patent publications related to the patent application of the invention are found:
1. a method for recycling waste salt containing phosphate (CN109607503A) comprises the steps of firstly pyrolyzing the waste salt containing phosphate at 300-500 ℃, mixing the pyrolyzed waste salt with water, fully dissolving the phosphate under the heating condition of 80-100 ℃, adding activated carbon, stirring, filtering to obtain a phosphate solution containing a small amount of sodium chloride, adjusting the pH value of the salt solution to 4-12, then cooling a hot phosphate solution at 70-90 ℃ at the cooling rate of 15-30 ℃/h, crystallizing to separate out phosphate solid, and recovering the filtrate after solid-liquid separation to obtain the phosphate. According to the invention, phosphate is recovered in the forms of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate and the like, so that resource recycling of waste salt is realized, the recovered phosphate has high purity and good grain size, the problem of poor crystallization effect caused by too fast temperature reduction in the recrystallization process is avoided, and simultaneously, the separated activated carbon and filtrate can be recycled through regeneration, so that zero discharge of wastewater is ensured.
2. A process for reclaiming the waste sodium chloride salt in dye production includes such steps as removing water from the waste salt in oxygen-free environment at different temp, gasifying the organic micromolecules, cracking the aromatic ring, carbonizing the condensed ring substances such as naphthalene and anthracene, dissolving the salt, removing particles, dissolving, and electrolyzing by bipolar membrane to obtain sodium hydroxide solution and diluted hydrochloric acid. The whole treatment process is simple, efficient, economical and feasible, and the resource recovery and utilization of the sodium chloride waste salt, the cracked micromolecular organic matter and the carbonized product are realized.
By contrast, the present patent application differs essentially from the above patent publications.
Disclosure of Invention
The utility model aims to overcome the weak point of current waste salt processing technique, provide a waste salt is tail gas processing system for resourceful treatment, this system structure connects simply, and convenient to use can make the pollutant in the flue gas reach emission standard completely after the pyrolysis exhaust-gas treatment of pyrolysis oven, and can retrieve the heat in the pyrolysis of pyrolysis oven is useless, and is with low costs, effectual, can use in the aspect of waste salt resourceful treatment.
The utility model provides a its technical problem take following technical scheme to realize:
a tail gas treatment system for waste salt recycling treatment comprises a secondary combustion chamber, a waste heat boiler, a quench tower, a bag-type dust remover, a precooler, a two-stage washing tower, a smoke whitening device, a chimney and a circulating water tank, wherein the secondary combustion chamber comprises an input end and a smoke output end, the input end of the secondary combustion chamber comprises a natural gas input end, a pyrolysis gas input end and an ammonia water input end, the natural gas input end is connected with natural gas, natural gas can be input into a secondary combustion chamber through the natural gas input end, the pyrolysis gas input end of the secondary combustion chamber is connected with pyrolysis waste gas of a pyrolysis furnace, the ammonia water input end is connected with ammonia water, and ammonia water can be input into the secondary combustion chamber through the ammonia water input end;
the input end of the waste heat boiler comprises a soft water input end and a smoke input end, the output end of the waste heat boiler comprises a steam output end and a smoke output end, the smoke input end of the waste heat boiler is connected with the smoke output end of the secondary combustion chamber, the soft water input end of the waste heat boiler is connected with soft water, soft water can be input into the waste heat boiler through the soft water input end, and the steam output end of the waste heat boiler is connected with the smoke whitening device;
the input end of the quenching tower comprises a flue gas input end and a quenching agent input end, the flue gas input end of the quenching tower is connected with the flue gas output end of the waste heat boiler, the quenching agent input end is connected with the quenching agent, the quenching agent can be input into the quenching tower through the quenching agent input end, the output end of the quenching tower is connected with the input end of the bag-type dust remover, an active carbon input end is arranged on a pipeline between the output end of the quenching tower and the bag-type dust remover, active carbon can be input into the pipeline between the output end of the quenching tower and the bag-type dust remover through the active carbon input end, the output end of the bag-type dust remover is connected with the input end of a precooler, and the output end of the precooler is connected;
the output end of the two-stage washing tower comprises a waste water output end and a flue gas output end, the waste water output end of the two-stage washing tower is respectively connected with the input end of the circulating water tank, the flue gas output end of the two-stage washing tower is connected with the input end of the flue gas whitening device, the output end of the flue gas whitening device is connected with the input end of the chimney, and the output end of the chimney can output flue gas which reaches the standard and is discharged;
the output end of the circulating water tank is connected with the input end of the two-stage washing tower, the circulating water tank can input alkali liquor into the two-stage washing tower, and the two-stage washing tower can remove pollutants in the flue gas to reach the emission standard.
Furthermore, the scrubber tower is a wet scrubber tower capable of removing acid gases.
The heating temperature in the secondary chamber is more than 1100 ℃, and the pyrolysis waste gas of the pyrolysis furnace stays in the secondary chamber for more than 2 seconds.
And the quenching tower is a spray quenching tower, the quenching agent adopts lime water, and the retention time of the flue gas in the quenching tower is less than 1 s.
Moreover, the bag-type dust collector selects a high-temperature-resistant material, and the temperature of tail gas entering the bag is controlled to be 220 +/-5 ℃;
or the quenching tower is a semi-dry quenching tower.
And a catalyst and a chelating agent are mixed in the washing liquid of the two-stage washing tower.
The tail gas treatment system for the waste salt recycling treatment is applied to the waste salt recycling treatment.
The utility model discloses the advantage that gains is with positive effect:
1. this system structural connection is simple, and convenient to use can make the pollutant in the flue gas reach emission standard completely after the pyrolysis exhaust-gas treatment of pyrolysis oven, and can retrieve the heat in the pyrolysis of pyrolysis oven is useless, and is with low costs, effectual, can use in the aspect of the waste salt resourceful treatment.
The pyrolysis waste gas generated in the pyrolysis process of the waste salt in the pyrolysis furnace can contain part of toxic gasThe pyrolysis flue gas generated by the pyrolysis furnace is introduced into a secondary combustion chamber to be heated to over 1100 ℃ and stays in the secondary combustion chamber for over 2 seconds, so that the waste gas is fully combusted and is completely oxidized into CO2And H2O; the method comprises the steps of carrying out heat recovery on high-temperature flue gas generated by a secondary combustion chamber, introducing the high-temperature flue gas exhausted by the secondary combustion chamber into a waste heat boiler for heat recovery, after the heat is recovered by the waste heat boiler, reducing the temperature of the flue gas from original 1100 ℃ to about 550 ℃ and then entering a quench tower, and taking a measure of quenching to reduce the residence time of the flue gas at 200-500 ℃ for reducing the chance of dioxin synthesis. The quench tower has the effect of cooling and deacidifying concurrently, adopts the spraying quench tower to cool down for tail gas, and the quenching agent adopts lime wash, can react with the acid gas in the tail gas, can effectively get rid of HCl, SOx, NOx etc. in the tail gas. The retention time of the flue gas in the quenching tower is less than 1s, and the temperature of the flue gas discharged from the quenching tower is reduced to 220 ℃ from about 550 ℃. The flue gas after temperature reduction and deacidification enters a bag-type dust remover, the flue gas after dust removal enters a wet deacidification system, and SO in the flue gas2HCl and NaOH solution further neutralize, and the pollutant in the flue gas reaches emission standard completely this moment, but the temperature is on the low side, still need disappear white device heating through the flue gas, avoids dew point corrosion and white cigarette to produce, and the flue gas through the heating is sent to the chimney through the draught fan and is up to standard discharged outward.
2. The waste heat boiler and the smoke whitening device of the system are connected, the smoke whitening device can utilize low-pressure steam generated by the waste heat boiler to carry out heat-recovery whitening treatment on smoke and then discharge the smoke, steam resources of the waste heat boiler are fully utilized, energy consumption is reduced, the effect of smoke whitening is achieved, and meanwhile equipment investment of smoke whitening is also reduced.
3. The treatment system utilizing the tail gas treatment system comprises a carbonization pyrolysis system of waste salt, a dissolution and filtration system of carbon-containing salt slag and an evaporation salt separation system which are sequentially connected, the system can be used for refining industrial waste salt, removing organic pollutants from the waste salt and mixing inorganic salt to treat the waste salt, and finally producing industrial secondary salt products, such as finished salt, such as anhydrous sodium sulfate, sodium chloride, sodium bicarbonate and the like, so that the waste salt is recycled, the treatment system has good economic benefit and good social benefit, and can be applied to the aspect of recycling treatment of the waste salt;
in addition, the system does not occupy a large amount of land, does not cause secondary pollution, has low treatment cost, does not generate secondary wastewater and sludge, can ensure the effect of physical and chemical treatment after dissolution of salts containing high organic matter concentration, is stable to use, can be applied to industrialization, and can prepare inorganic salt products with higher purity.
4. The treatment system utilizing the tail gas treatment system is suitable for recycling treatment of waste salt slag generated in the industrial production process, and the waste salt is subjected to the processes of medium-temperature pyrolysis carbonization, dissolution filtration and evaporation salt separation to finally obtain product salt with higher purity, and the generation amount of mixed salt is very small. The system has advanced technology, easy operation and controllable product quality, and can ensure the whole process resource utilization of the waste salt.
5. The rotary pyrolysis furnace of the disposal system of the tail gas treatment system is used for carrying out medium-temperature pyrolysis on organic matters under the anaerobic or anoxic condition, and because the process is carried out in the reducing atmosphere, the generation of dioxin can be avoided, and the rotary pyrolysis furnace has the characteristics of high pyrolysis efficiency, simple equipment and low carbon residue yield; in addition, the rotary pyrolysis furnace can adjust the residence time of material pyrolysis according to the physical and chemical properties of the material, the rotary pyrolysis furnace is designed to operate at the optimal rotating speed, the pyrolysis efficiency is fully ensured, a variable frequency and variable speed motor can be arranged, variable frequency and variable speed are adopted, and the rotary pyrolysis furnace is flexible to use.
6. The primary ultrafiltration device and the secondary ultrafiltration device of the disposal system utilizing the tail gas treatment system are immersed ultrafiltration equipment, and the immersed ultrafiltration process is the most economic and energy-consuming process in the current separation and purification process, and has wide application and mature technology. The submerged ultrafiltration has the following advantages:
a) the immersed ultrafiltration membrane has good and stable effluent quality, and the effluent turbidity is usually lower than 1 NTU.
b) Wide application range and easy cleaning. The membrane material is PVDF (polyvinylidene fluoride) material, and has strong chemical resistance and wide application range. The components can be cleaned online or offline in time during filtration.
c) Low energy consumption and high efficiency. At about 0.02m3The space includes 10m2A hollow fiber membrane. The membrane module is immersed in water, and can keep high flux at low pressure of 0.05MPa, so the energy consumption is very low.
d) High filtering precision and continuous yarn. The hollow fiber used has uniform pores of less than 0.05 μm, and can remove microorganisms, colloids, algae, and other turbidity-causing substances. And due to TiO2Due to hybridization, the tensile property of the membrane yarn is far stronger than that of a common PVDF membrane.
e) The occupied area is small. Solid-liquid separation equipment such as precipitation and filtration is not needed, so that the whole system has simple flow and easy integration, and the occupied area of the system is greatly reduced.
f) The management is simple and convenient, the automation degree is high, and the operation cost is low. No disinfection equipment is needed, and no medicine is needed. The whole machine can realize automatic intermittent operation.
7. The evaporative crystallization system of the disposal system utilizing the tail gas treatment system comprises an MVR (mechanical vapor recompression) evaporator, the evaporative crystallization system can adopt an MVR evaporation process technology, and simultaneously, vapor condensate generated in the MVR evaporation system is pumped back to a salt dissolving tank to dissolve inorganic salt after pyrolysis, so that the vapor condensate is recycled, the consumption of industrial water in the dissolution system is reduced, and the consumption of public works is reduced.
Drawings
FIG. 1 is a schematic diagram of the structural connection of the system of the present invention;
figure 2 is a schematic view of the structural connection of the waste salt recycling treatment system utilizing the system of the utility model.
Detailed Description
The present invention will be described in further detail with reference to specific examples, which are provided for illustrative purposes only and are not intended to be limiting, and the scope of the present invention should not be limited thereby.
The structures not described in detail in the present invention can be understood as the conventional structures in the art.
A tail gas treatment system for waste salt recycling treatment is shown in figure 1 and comprises a secondary combustion chamber, a waste heat boiler, a quench tower, a bag-type dust collector, a precooler, a two-stage washing tower, a flue gas whitening device, a chimney and a circulating water tank, wherein the secondary combustion chamber comprises an input end and a flue gas output end, the input end of the secondary combustion chamber comprises a natural gas input end, a pyrolysis gas input end and an ammonia water input end, the natural gas input end is connected with natural gas, natural gas can be input into the secondary combustion chamber through the natural gas input end, the pyrolysis gas input end of the secondary combustion chamber is connected with pyrolysis waste gas of a pyrolysis furnace, the ammonia water input end is connected with ammonia water, and the ammonia water input end can input ammonia water into the secondary combustion chamber;
the input end of the waste heat boiler comprises a soft water input end and a smoke input end, the output end of the waste heat boiler comprises a steam output end and a smoke output end, the smoke input end of the waste heat boiler is connected with the smoke output end of the secondary combustion chamber, the soft water input end of the waste heat boiler is connected with soft water, soft water can be input into the waste heat boiler through the soft water input end, and the steam output end of the waste heat boiler is connected with a smoke whitening device;
the input end of the quenching tower comprises a flue gas input end and a quenching agent input end, the flue gas input end of the quenching tower is connected with the flue gas output end of the waste heat boiler, the quenching agent input end is connected with the quenching agent, the quenching agent can be input into the quenching tower through the quenching agent input end, the output end of the quenching tower is connected with the input end of the bag-type dust remover, an active carbon input end is arranged on a pipeline between the output end of the quenching tower and the bag-type dust remover, active carbon can be input into the pipeline between the output end of the quenching tower and the bag-type dust remover through the active carbon input end, the output end of the bag-type dust remover is connected with the input end of a precooler, and the output end of the precooler is connected;
the output end of the two-stage washing tower comprises a waste water output end and a flue gas output end, the waste water output end of the two-stage washing tower is respectively connected with the input end of the circulating water tank, the flue gas output end of the two-stage washing tower is connected with the input end of the flue gas whitening device, the output end of the flue gas whitening device is connected with the input end of the chimney, and the output end of the chimney can output flue gas which reaches the standard and is discharged;
the output end of the circulating water tank is connected with the input end of the two-stage washing tower, the circulating water tank can input alkali liquor into the two-stage washing tower, and the two-stage washing tower can remove pollutants in the flue gas to reach the emission standard.
The waste salt recycling treatment system of the tail gas treatment system for waste salt recycling treatment comprises a carbonization pyrolysis system of waste salt, a dissolution and filtration system of carbon-containing salt slag and an evaporation salt separation system which are sequentially connected as shown in fig. 2, wherein the carbonization pyrolysis system of the waste salt can be used for performing carbonization pyrolysis treatment on waste salt I consisting of sodium chloride, sodium sulfate monomer salt or mixed waste salt, and can be used for treating tail gas; the dissolving and filtering system for the carbon-containing salt slag can dissolve and filter the carbon-containing salt slag treated by the carbonization and pyrolysis system for waste salt; the evaporation salt separation system can perform evaporation concentration, fractional crystallization and drying treatment on the strong brine treated by the dissolution and filtration system of the carbon-containing salt slag to obtain the product salt.
In this embodiment, the waste salt carbonization and pyrolysis system comprises a material conveying system, a rotary pyrolysis furnace, a combustion system and a tail gas treatment system, wherein an input end of the material conveying system can input waste salt I to be treated, an output end of the material conveying system is connected with an input end of the rotary pyrolysis furnace, an output end of the rotary pyrolysis furnace comprises a carbon-containing salt slag output end and a pyrolysis gas output end, the carbon-containing salt slag output end is connected with a carbon-containing salt slag dissolving and filtering system, and the pyrolysis gas output end is connected with the tail gas treatment system; the input end of the combustion system is connected with natural gas, and the output end of the combustion system is also connected with the input end of the rotary pyrolysis furnace;
the tail gas treatment system comprises a secondary combustion chamber, a waste heat boiler, a quench tower, a bag-type dust collector, a precooler, a two-stage washing tower, a flue gas whitening device, a chimney and a circulating water tank, wherein the secondary combustion chamber comprises an input end and a flue gas output end, the input end of the secondary combustion chamber comprises a natural gas input end, a pyrolysis gas input end and an ammonia water input end, the natural gas input end is connected with natural gas, natural gas can be input into a secondary combustion chamber through the natural gas input end, the pyrolysis gas input end of the secondary combustion chamber is connected with the pyrolysis gas output end of the rotary pyrolysis furnace, the ammonia water input end is connected with ammonia water, and ammonia water can be input into the secondary combustion chamber through;
the input end of the waste heat boiler comprises a soft water input end and a smoke input end, the output end of the waste heat boiler comprises a steam output end and a smoke output end, the smoke input end of the waste heat boiler is connected with the smoke output end of the secondary combustion chamber, the soft water input end of the waste heat boiler is connected with soft water, soft water can be input into the waste heat boiler through the soft water input end, and the steam output end of the waste heat boiler is connected with the evaporation salt separation system and the smoke whitening device;
the input end of the quenching tower comprises a flue gas input end and a quenching agent input end, the flue gas input end of the quenching tower is connected with the flue gas output end of the waste heat boiler, the quenching agent input end is connected with the quenching agent, the quenching agent can be input into the quenching tower through the quenching agent input end, the output end of the quenching tower is connected with the input end of the bag-type dust remover, an active carbon input end is arranged on a pipeline between the output end of the quenching tower and the bag-type dust remover, active carbon can be input into the pipeline between the output end of the quenching tower and the bag-type dust remover through the active carbon input end, the output end of the bag-type dust remover is connected with the input end of a precooler, and the output end of the precooler is connected;
the output end of the two-stage washing tower comprises a waste water output end and a flue gas output end, the waste water output end of the two-stage washing tower is respectively connected with the evaporation salt separation system and the input end of the circulating water tank, the flue gas output end of the two-stage washing tower is connected with the input end of the flue gas whitening device, the output end of the flue gas whitening device is connected with the input end of the chimney, and the output end of the chimney can output flue gas which is discharged up to the standard;
the output end of the circulating water tank is connected with the input end of the two-stage washing tower, the circulating water tank can input alkali liquor into the two-stage washing tower, and the two-stage washing tower can remove pollutants in the flue gas to reach the emission standard.
In this embodiment, the material conveying system adopts a spiral feeding structure, a variable frequency speed regulating motor is arranged in a matching manner, and the material discharging system also adopts a spiral feeding structure; preferably, the contact part of the spiral feeding structure and the material adopts stainless steel 316L material;
or the combustion system is a combustor and is used for providing heat for the pyrolysis furnace, the fuel is natural gas, preferably, the interior of a combustion chamber of the combustor is built by adopting refractory materials, the middle of the combustion chamber is made of section steel and is provided with a heat insulation layer, and the exterior of the combustion chamber is sealed by adopting a color steel plate;
alternatively, the scrubber tower is a wet scrubber tower capable of removing acid gases.
In this embodiment, the pyrolysis process of the waste salt in the rotary pyrolysis furnace is to incompletely oxidize the organic matters in the waste salt to decompose into CH under the anoxic condition at 550-600 ℃4/CO/H2And coke. Because the reaction temperature is low, dioxin substances are not easy to generate. Preferably, the rotary pyrolysis furnace adopts an upper-lower two-section pyrolysis furnace for pyrolysis, the pyrolysis temperature of the upper section pyrolysis furnace is 400-500 ℃, the low-temperature drying process is adopted, and the pyrolysis temperature of the lower section is 550-600 ℃ high-temperature pyrolysis process.
In this embodiment, the pyrolysis gas generated in the pyrolysis process of the waste salt in the rotary pyrolysis furnace contains part of toxic gas, and must be burned, the pyrolysis flue gas generated by the pyrolysis furnace is introduced into the second combustion chamber to be heated to over 1100 ℃, and stays in the second combustion chamber for over 2 seconds, so that the waste gas is sufficiently combusted and completely oxidized into CO2And H2O; the high-temperature flue gas generated by the secondary combustion chamber is subjected to heat recovery, the high-temperature flue gas discharged by the secondary combustion chamber is introduced into a waste heat boiler for heat recovery, and after the heat is recovered by the waste heat boiler, the temperature of the flue gas is reduced from original 1100 ℃ to about 550 DEG CAnd (3) entering a quenching tower on the right, and taking a measure of quenching to reduce the residence time of the flue gas at 200-500 ℃ in order to reduce the chance of synthesizing dioxin. The quench tower has the effect of cooling and deacidifying concurrently, adopts the spraying quench tower to cool down for tail gas, and the quenching agent adopts lime wash, can react with the acid gas in the tail gas, can effectively get rid of HCl, SOx, NOx etc. in the tail gas. The retention time of the flue gas in the quenching tower is less than 1s, and the temperature of the flue gas discharged from the quenching tower is reduced to 220 ℃ from about 550 ℃. The flue gas after temperature reduction and deacidification enters a bag-type dust remover, the flue gas after dust removal enters a wet deacidification system, and SO in the flue gas2HCl and NaOH solution further neutralize, and the pollutant in the flue gas reaches emission standard completely this moment, but the temperature is on the low side, still need disappear white device heating through the flue gas, avoids dew point corrosion and white cigarette to produce, and the flue gas through the heating is sent to the chimney through the draught fan and is up to standard discharged outward.
In the embodiment, the bag-type dust collector is made of a high-temperature-resistant material, and the temperature of tail gas entering the bag is controlled to be 220 +/-5 ℃ so as to avoid the blockage of the filter bag caused by acid mist condensation or water vapor condensation;
or the quenching tower is a semi-dry quenching tower (semi-dry scrubbing gas); or a catalyst (CuCl) is mixed in the washing liquid of the two-stage washing tower2) And chelating agents to promote more water soluble HgCl2And fixing the circulating liquid absorbing the mercury by using a chelating agent.
One up-to-standard feasibility analysis of flue gas emission is as follows:
acid gas control technique
The method is characterized in that acid gas in the tail gas is deacidified and cooled by adopting a semidry method, lime water is sprayed into a spray quench tower to react with the acid gas to remove acid, and the sprayed lime water has the cooling effect.
In order to ensure that the flue gas can meet the emission requirement, a two-stage washing tower is adopted for further desulfurization after cloth bag dust removal. The flue gas from the precooler enters a wet scrubber A, the flue gas is introduced from the bottom of the scrubber and meets sprayed alkaline solution in the rising process of the flue gas, and the acidic gas in the flue gas and the alkaline solution are subjected to neutralization reaction:
2NaOH+SO2→Na2SO3+H2O
the wet sodium-alkali absorption method actually utilizes NaXH2-XSO3(X1-2) absorbing SO in flue gas in a continuous circulating process2Acid salt NaHSO formed during absorption3To SO2Has no absorption capacity, and the NaHSO in the absorption liquid is absorbed along with the progress of the absorption process3The absorption capacity of the absorption liquid is reduced due to the increase of the amount, so that alkali liquor needs to be supplemented into the absorption liquid to ensure that part of NaHSO3Conversion to Na2SO3To maintain Na in the absorption liquid2SO3Is relatively stable to maintain the absorption capacity of the absorption liquid.
At the same time, SO contained in the flue gas3Acidic gases such as HCl are also absorbed by the absorbent, and the following reactions occur:
therefore, the absorption section of the absorption tower in the sodium-alkali desulfurization process absorbs SO in the flue gas2Absorbing to obtain sodium sulfite or sodium bisulfite intermediate and small amount of sodium sulfate and sodium chloride. The pollutants in the flue gas are removed by the flue gas through a two-stage washing tower to reach the emission standard.
The removal efficiency of the acid gas of the system on the acid gas is about more than 90 percent through the semi-dry deacidification of the quench tower, and the secondary reaction of the reaction agent on the surface of the bag-type dust remover can improve the removal rate of the acid gas of the whole system (HCl98 percent, SO 98 percent)xMore than 90 percent), in addition, the subsequent two stages of wet scrubber towers carry out acid-base neutralization reaction in the scrubber towers in a mode of spraying alkali liquor so as to remove the hydrogen chloride in the flue gas from the flue gas, the removal efficiency of the wet scrubber towers can reach more than 95 percent, and the vulcanization can be removed simultaneouslyHydrogen, sulfur dioxide, and other acidic gases. The formed acid washing waste water (the mixed liquid of the acid salts containing sodium bisulfite and sodium sulfite) is discharged to the front end of an evaporation crystallization system after being subjected to pH adjustment, is mixed with condensed water to be used as dissolved salt water, and enters an evaporation unit after being subjected to precipitation and filtration. Realizing zero discharge of production wastewater.
·NOXPollution control technology
The nitrogen oxides generated in the combustion process are mainly divided into 3 types, namely Fuel nitrogen oxides (Fuel NOx), the sources of which are generated by burning nitrogen components in Fuel, transient nitrogen oxides (PromptNOx), which are generated by the action of CO and nitrogen-containing organic gas ions in flame and Thermal nitrogen oxides (Thermal NOx), which are generated by the action of nitrogen and oxygen in air under the high-temperature environment exceeding 1500 ℃, in the system, because a clean pyrolysis mode of drying in a first-stage rotary pyrolysis furnace and pyrolysis in a second-stage rotary pyrolysis furnace is adopted, the generation of the nitrogen oxides is little, and the temperature of a second combustion chamber is only 1100 ℃, which is far less than 1500 ℃, so that the generation amount of the Thermal nitrogen oxides is basically not generated.
In the system, the SNCR method can be adopted, ammonia water is injected into the secondary combustion chamber, and NO is generated in the region of 850-1050 DEG CXIs reduced to N by reaction with ammonia2. NH3 which is not completely reacted reacts with HCl in the flue gas to generate NH4Cl, residual NH in flue gas3Typically less than 10 x 10-6. At present, SNCR is most widely applied in a flue gas purification system, and the American environmental protection agency and the European Union recommend that SNCR is adopted as a denitration process for solid waste incineration flue gas.
Control technique of soot (Dust)
The system for preventing and controlling the smoke dust utilizes a bag dust removal and wet type washing tower double dust removal design, a proper bag is selected, 99.9% of dust pollutants can be effectively removed basically, the bag dust removal is the only equipment which is proved to be capable of effectively removing PM2.5 at present, and the wet type washing tower after the bag dust removal can also collect small particles into large particles by utilizing the absorption force of water on the smoke dust, and the large particles are washed into circulating water to be discharged.
The bag-type dust collector is made of high-temperature-resistant materials, and the temperature of tail gas entering the bag is controlled to be about 220 ℃ so as to avoid the blockage of the filter bag caused by acid mist condensation or water vapor condensation.
Volatile Organic Compounds (VOCs)
The possible generation link of VOCs in the system is in the drying stage of the waste salt, and organic matters in the waste salt can be volatilized out and enter a secondary combustion chamber along with hot air flow. When the flue gas enters a second combustion chamber with high temperature, volatile substances and pyrolysis gas are fully combusted and converted into stable and harmless carbon dioxide and water under the action of sufficient air, and heat energy of the carbon dioxide and the water is released.
Heavy metal control technique
When the bag-type dust remover is used together with a quenching tower (semi-dry scrubbing gas), the removal effect of heavy metals except mercury is very good. The mercury metal is not easy to condense due to its high saturated vapor pressure, and in order to reduce the emission concentration of mercury, active carbon is sprayed in front of the bag-type dust remover to enhance the adsorption effect on mercury metal, and in the wet treatment process, a catalyst (CuCl) can be added into the washing liquid of the washing tower2) Promoting more water-soluble HgCl2And fixing the circulating liquid absorbing the mercury by using a chelating agent.
Dioxin control technique
The system is provided with a secondary combustion chamber at the rear end of the pyrolysis furnace, smoke after pyrolysis enters the secondary combustion chamber immediately after being discharged from the pyrolysis furnace, sufficient air and auxiliary fuel are introduced into the secondary combustion chamber to heat the smoke to 1100 ℃, so that the smoke is mixed and combusted in the secondary combustion chamber and stays for more than 2 seconds, and organic matters are completely converted into harmless CO2And H2O and substantially destroys any dioxins and dioxin precursors that may be generated. Because the heat value of volatile substances and pyrolysis gas from the pyrolysis furnace is low and is not enough to maintain the temperature of the secondary furnace at 1100 ℃, the secondary combustion chamber is required to provide additional auxiliary fuel and combustion air to provide enough heat energy. The high-temperature flue gas at the outlet of the secondary combustion chamber immediately enters a waste heat boiler to recover heat. The flue gas is cooled and deacidified in a quenching tower after being heat recovered in a waste heat boiler, and then enters a bag-type dust remover, an active carbon powder injection device is additionally arranged in a flue before entering a bag-type dust remover, and powdered active carbon is periodically injected into the flue gasThe activated carbon forms a carbon powder layer on the surface of the cloth bag, the carbon powder layer can effectively adsorb dioxin, theoretically, the smoke stays in a high-temperature state of 1100 ℃ in a combustion chamber for more than 2 seconds, the dioxin is destroyed, and the activated carbon powder is matched with the cloth bag for dust removal, so that no dioxin is discharged. Activated carbon at a ratio of 200mg/Nm3The amount of flue gas is added.
In this embodiment, the system for dissolving and filtering the carbon-containing salt slag comprises a salt dissolving tank, a primary ultrafiltration device, a carbon slag collector, a secondary ultrafiltration device and a trace solid residue collector, wherein the output end of the rotary pyrolysis furnace is connected with the input end of the salt dissolving tank, the output end of the salt dissolving tank is connected with the input end of the primary ultrafiltration device, the pipeline between the salt dissolving tank and the primary ultrafiltration device is connected with the input end of a precipitator, the precipitator can be input into the pipeline between the salt dissolving tank and the primary ultrafiltration device through the precipitator input end, the output end of the primary ultrafiltration device comprises a carbon residue output end and a strong brine output end, the carbon residue output end of the primary ultrafiltration device is connected with the input end of the carbon residue collector, the output end of the carbon slag collector is connected with the second combustion chamber, and the filtered carbon slag is conveyed to the second combustion chamber to be further combusted; the strong brine output end of the primary ultrafiltration device is connected with the input end of the secondary ultrafiltration device, the pipeline between the primary ultrafiltration device and the secondary ultrafiltration device is connected with the precipitant input end, and the precipitant can be input into the pipeline between the primary ultrafiltration device and the secondary ultrafiltration device through the precipitant input end;
the output end of the second-stage ultrafiltration device comprises a residue output end and a strong brine output end, the residue output end of the second-stage ultrafiltration device is connected with a trace solid residue collector, and trace solid residues in the trace solid residue collector can be transported to a cement kiln for comprehensive utilization or processed by a unit with related quality.
In this embodiment, the system for dissolving and filtering the slag containing carbon salts further includes a chemical dosing system (not shown in the figure), which is configured with the salt dissolving tank to remove heavy metal ions or other impurity ions (such as calcium, magnesium, etc.) that may exist in the waste salts;
or the primary ultrafiltration device and the secondary ultrafiltration device are immersed ultrafiltration equipment.
In this embodiment, the evaporation salt separation system comprises a carbonation tower, a magma thickener and an evaporation crystallization system, wherein the input end of the carbonation tower comprises a strong brine input end and CO2An input end, wherein the strong brine input end of the carbonating tower is connected with the strong brine output end of the second-stage ultrafiltration device, and the CO of the carbonating tower2Input terminal and CO2Is connected to the CO via2The input end can input CO into the carbonating tower2The output end of the carbonating tower is connected with the input end of the crystal slurry thickener, and the output end of the crystal slurry thickener comprises NaHCO3An output terminal and a crystal slurry output terminal, the NaHCO3Output end can output NaHCO3Crude product of NaHCO3The crude product can be centrifuged, dried and packaged to obtain NaHCO3Producing a product; the crystal mush output end is connected with the input end of the evaporative crystallization system, the output end of the evaporative crystallization system comprises a condensate water output end and a salt output end, the condensate water output end can output condensate water after treatment, the condensate water output end is respectively connected with the salt dissolving tank and the water storage tank, and the salt output end can output finished salt, such as NaCl, anhydrous sodium sulphate, KCl and Ca (NO)3)2Etc.;
the concentrated brine output end of the second-stage ultrafiltration device is also directly connected with the input end of the evaporative crystallization system, the pipeline between the second-stage ultrafiltration device and the evaporative crystallization system is provided with an acid input end, and acid can be input into the pipeline between the second-stage ultrafiltration device and the evaporative crystallization system through the acid input end.
In this embodiment, the evaporative crystallization system includes an mvr (mechanical Vapor recompression) evaporator, or the evaporative crystallization system includes an mvr (mechanical Vapor recompression) evaporator and a single-effect evaporator connected to each other.
The evaporative crystallization system of the system comprises an MVR (mechanical Vapor recompression) evaporator, steam condensate generated in the MVR evaporation system is pumped back to a salt dissolving tank, and inorganic salt after pyrolysis is dissolved, so that the steam condensate is recycled, the consumption of industrial water in the dissolving system is reduced, and the consumption of public works is reduced; in addition, the mixed inorganic salt can be separated and crystallized step by adopting a process combining MVR evaporation technology and single-effect evaporation. Firstly, in an MVR evaporation system, Na2SO4 is crystallized and separated under the high-temperature working condition, then the mother liquor is decompressed and cooled, and NaCl is crystallized and separated under the low-temperature working condition of the single-effect evaporation system, SO that the salt and nitrate separation is realized.
In this embodiment, the disposal system further includes a waste salt II disposal system (configured according to the actual situation of the waste salt collected at the later stage), and the main components of the waste salt II are mirabilite and a small amount of chromium salt, and no organic pollutant is contained, so that the waste salt II does not need to be pyrolyzed. Waste salt II handles system includes acid-soluble system and edulcoration device, waste salt II can be input to acid-soluble system's input, the input of edulcoration device includes acid-soluble treatment fluid input and reductant/precipitant input, acid-soluble system's output is connected the setting with the acid-soluble treatment fluid input of edulcoration device, and the reductant/precipitant input of this edulcoration device is connected the setting with reductant/precipitant, can be to inputing reductant/precipitant in the edulcoration device through this reductant/precipitant input, and the output of this edulcoration device includes impurity filter residue output and filtrating output, impurity filter residue can be exported to impurity filter residue output, the filtrating output of edulcoration device is connected the setting with evaporative crystallization system's input.
The utility model discloses a theory of operation and flow of waste salt resourceful treatment processing system are as follows:
the system is suitable for recycling treatment of sodium chloride, sodium sulfate monomer waste salt and mixed waste salt thereof generated in the industrial production process. In the production process, the waste salt is roughly classified into waste salt I and waste salt II according to the type of the waste salt. Waste salt I: mainly comprises sodium chloride, sodium sulfate monomer salt or mixed waste salt. The partial waste salt is subjected to medium-temperature pyrolysis carbonization, dissolution and filtration according to different component types, and enters different evaporation salt separation processes respectively, and finally the product salt with higher purity is obtained. The waste salt II comprises main components of mirabilite and a small amount of chromium salt, and does not contain organic pollutants, so that the waste salt II does not need to be subjected to pyrolysis treatment. The system has advanced technology, easy operation and controllable product quality, and can ensure the whole process resource utilization of the waste salt.
1. In-plant waste salt transport
The waste salt of depositing temporarily in the warehouse transports to the pyrolysis workshop through fork truck, promotes to the feed inlet by hoisting device again, and waste salt falls into in the feed inlet and mixes the salt pond, through compatible back, by screw conveyor to pyrolysis oven feed chute, screw conveyor is connected to the feed chute lower extreme, delivers waste salt to the pyrolysis oven in order to set for the input speed. The utility model discloses adopt spiral pay-off structure, join in marriage the variable frequency speed-regulating motor better, discharge system adopts spiral pay-off structure equally. The contact part of the screw conveyer and the material is made of stainless steel 316L.
2. Charring pyrolysis of waste salt
The pyrolysis process of waste salt is a complex chemical reaction process, and comprises chemical reactions such as breaking of bonds of macromolecules, isomerization and the like. During pyrolysis, the intermediate products have two trends, namely a cracking process for changing macromolecules into small molecules or even gas, and a polymerization process for polymerizing the small molecules into larger molecules. The pyrolysis process comprises a cracking reaction, a dehydrogenation reaction, a hydrogenation reaction, a condensation reaction, a bridge bond decomposition reaction and the like.
The carbonization pyrolysis system of waste salt comprises a material conveying system, a pyrolysis furnace, a combustion system and a tail gas treatment system. The useless salt that produces is collected to the warehouse by the useless haulage vehicle of special danger and is kept in the back, and useless salt passes through spiral feeding structure, sends to the pyrolysis oven and carries out the carbonization pyrolysis, and the pyrolysis oven is joined in marriage variable frequency speed regulation motor. The pyrolysis process of the waste salt is to cause the organic matters in the waste salt to be incompletely oxidized and decomposed into CH4/CO/H2 and coke under the condition of 550-600 ℃ and oxygen deficiency. Because the reaction temperature is low, dioxin-like substances are not easy to generate. The system can be designed with 2 sets of parallel pyrolysis systems, and the pyrolysis process of each set of pyrolysis system is carried out in two stages.
The amount of combustible gas generated in the waste salt pyrolysis process is large,especially, at higher temperatures, more than 50% of the organic components in the waste salts are converted into gaseous products. These products are described in H2、CO、CH4Mainly, the calorific value is as high as 6.37 multiplied by 103～1.021×104kJ/kg. Most of the gas becomes a combustible gas product, except for a small portion of the heat required for the pyrolysis process. Because the waste salt belongs to dangerous waste, the pyrolysis gas can not be directly utilized and must be combusted, so that the toxic gas in the pyrolysis gas can be fully combusted into carbon dioxide and water.
3. Dissolving and filtering of carbon-containing salt residue
After the waste salt is pyrolyzed and carbonized by a rotary pyrolyzing furnace, organic matters in the waste salt are removed, and inorganic salt containing a small amount of coke (carbon slag) is obtained. Dissolving carbon-containing inorganic salt obtained by a pyrolysis system in hot distilled water, and filtering carbon residue by an immersion type ultrafiltration process to obtain strong brine. The dissolving and filtering unit is provided with two stages of filtering devices, and the impurity ions are removed by adding a precipitator (such as alkali liquor). After two-stage filtration and purification, the concentrated salt water is selected to enter a corresponding evaporation system according to the components of inorganic salts contained in the concentrated salt water. And sending the filtered carbon residue to a second combustion chamber for further combustion. In order to avoid accumulation of incombustibles in the system, the solid waste slag (mainly inorganic salt precipitate) discharged from the dissolving and filtering unit is collected at regular intervals and is delivered to a unit with relevant qualification for treatment.
In addition, for waste salt II which is difficult to dissolve in water, the main components of the waste salt are mirabilite and a small amount of chromium salt, organic pollutants are not contained, the waste salt is subjected to acidification, reduction and precipitation treatment, impurity ions are separated out, after passing through an impurity removal device, the obtained sodium sulfate solution and the salt solution which is subjected to pyrolysis carbonization and dissolution filtration treatment are mixed and enter an evaporation system, and salt is crystallized. The salt dissolving tank can be provided with a chemical dosing system in a matching way to remove heavy metal ions or other miscellaneous ions (such as calcium, magnesium and the like) possibly existing in the waste salt.
4. Evaporative salt separation process
The waste salt is pyrolyzed and carbonized to remove organic matters, and then dissolved and filtered to remove carbon residue, and the formed strong brine enters an evaporation system, and is evaporated, concentrated, crystallized and dried to form product salt. Different salt separation routes are adopted according to the expected waste salt types.
(1) For waste salt with a single inorganic salt component as raw material: the strong salt after pyrolysis carbonization, dissolution and filtration is evaporated by adopting an MVR evaporation concentration process (the crystallization temperature of sodium chloride is 90-95 ℃, and the crystallization temperature of sodium sulfate is 85-90 ℃) to crystallize the single-component inorganic salt.
(2) For waste salt containing sodium chloride and sodium sulfate bi-component inorganic salt: and (3) putting the concentrated brine obtained after pyrolysis, carbonization, dissolution and filtration into a salt and nitrate separation system, crystallizing NaCl and Na2SO4 & 10H2O respectively in different working procedures through a fractional crystallization process, drying NaCl through a fluidized bed, and packaging to obtain the product NaCl salt. Na2SO4 & 10H2O was sent to a one-component evaporation system to remove the crystal water to prepare anhydrous sodium sulfate.
(3) For waste salts containing three inorganic salt components of NaCl-Na2SO4-Na2CO 3: under the condition that the content of Na2CO3 is low (lower than 0.5%), sulfuric acid is added into the dissolving and filtering unit to convert Na2CO3 into Na2SO4, and then sodium chloride products, namely salt and anhydrous sodium sulphate, are obtained through a salt-nitrate separation and refining route. For waste salt containing three inorganic salt components of NaCl-Na2SO4-Na2CO3, under the condition of high Na2CO3 content, the evaporation unit is provided with a carbonator salt separation system to separate NaHCO3。
The main function of the carbonating tower is to convert Na2CO3 contained in the wastewater into NaHCO3, thereby realizing the separation of carbonate from sulfate/sodium chloride salt. By blowing CO2 into the wastewater, Na2CO3 in the system is completely converted into NaHCO3, NaHCO3 is firstly separated out from the system, so that the carbonate is separated, and the salt solution (crystal slurry) with NaHCO3 crystals after the reaction is discharged from the bottom of the carbonization tower and enters a crystal slurry thickener to carry out primary separation on the crystals and the salt solution. Supernatant (filtrate) at the upper part of the magma thickener overflows into a filtrate storage tank for collection, sodium bicarbonate is heated and dried to generate sodium carbonate, and mother liquor returns to the front evaporation section after carbonization and separation; then enters a corresponding NaCl-Na2SO4 evaporative crystallization system for further desalting treatment. The thickened magma is further dewatered by flowing into a centrifugal separator. And conveying the dehydrated crystals to an airflow dryer for drying, and finally packaging the dried product in a product packaging line to obtain the product sodium carbonate pure salt, the product sodium chloride pure salt and anhydrous sodium sulphate.
5. Tail gas treatment
The tail gas generated by the pyrolysis system is treated by burning in a secondary combustion chamber, recovering heat of a waste heat boiler, quenching and cooling, removing dust by a cloth bag, two-stage spray washing and removing white by flue gas heat exchange.
Pyrolysis flue gas generated by pyrolysis of waste salt in the production process is introduced into a secondary combustion chamber and heated to over 1100 ℃, so that the waste gas is fully combusted and is completely oxidized into CO2 and H2O; sufficient air and auxiliary fuel are introduced into the secondary combustion chamber to heat the flue gas to 1100 ℃ so that the pyrolysis gas is mixed and combusted in the secondary combustion chamber and stays for more than 2 seconds, and the harmful gas is thoroughly decomposed and combusted and is completely converted into harmless CO2And H2O and substantially destroys any dioxins and dioxin precursors that may be generated. Theoretically, dioxin is destroyed when the smoke gas in the secondary combustion chamber stays for more than 2 seconds at the high temperature of 1100-1200 ℃. The high-temperature flue gas at the outlet of the secondary combustion chamber (for example, the main components of the secondary combustion chamber can comprise a refractory brick which is made of a steel plate and is internally lined with a corrosion-resistant and high-temperature-resistant lining, a temperature measuring point, a pressure measuring point, an oxygen content measuring point, a secondary air port, a burner port, an observation port, an explosion-proof door arranged at the top of the secondary combustion chamber and an emergency discharge chimney) has heat recovery value, and a waste heat boiler is generally adopted to recover the waste heat of the flue gas and produce process steam required by the regeneration process.
After heat exchange is carried out on high-temperature flue gas exhausted from the secondary combustion chamber through a waste heat boiler, the temperature is reduced from original 1100 ℃ to about 550 ℃ and then the high-temperature flue gas enters a quenching tower, so that the residence time of the flue gas at 200-500 ℃ is reduced for reducing the chance of synthesis of dioxin, and the measure adopted is 'quenching'. The quench tower has the effect of cooling and deacidifying concurrently, adopts the spraying quench tower to cool down for tail gas, and the quenching agent adopts lime wash, can react with the acid gas in the tail gas, can effectively get rid of HCl, SOx, NOx etc. in the tail gas. The retention time of the flue gas in the quenching tower is less than 1s, and the temperature of the flue gas discharged from the quenching tower is reduced to 220 ℃ from about 550 ℃. The flue gas after temperature reduction and deacidification enters the bag-type dust remover, and the temperature of the flue gas entering the bag-type dust remover is more than 200 ℃, so that bag-type dust removal can be avoidedThe dew phenomenon of the device, the flue gas after dust removal enters a wet deacidification system through a precooler, and SO in the flue gas2HCl and NaOH solution are further neutralized and removed.
The double dust removal design of the bag dust removal and the wet scrubber tower is adopted, a proper bag is selected, 99.9% of dust pollutants can be removed basically, the bag dust removal is the only equipment which is proved to be capable of effectively removing PM2.5 at present, and the wet scrubber tower after the bag dust removal can also collect small particles into large particles by utilizing the absorption force of water on the smoke dust, and the large particles are washed into circulating water to be discharged. Acid gas in the flue gas is subjected to acid-base neutralization reaction in the washing tower in an alkali liquor spraying mode by utilizing the wet washing tower, so that hydrogen chloride in the flue gas is removed from the flue gas, the removal efficiency of the wet washing tower can reach more than 95%, and various acid gases such as hydrogen chloride, sulfur dioxide and the like can be removed.
After the processes of quenching, dedusting, washing and purifying, the pollutants in the flue gas completely reach the emission standard, but the temperature is low, a flue gas white elimination device is needed to avoid dew point corrosion and white smoke generation, and the heated flue gas is sent to a chimney through a draught fan to be discharged after reaching the standard.
Although the embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore, the scope of the invention is not limited to the embodiments disclosed.
Claims (5)
1. The utility model provides a waste salt is tail gas processing system for resourceful treatment which characterized in that: the tail gas treatment system comprises a secondary combustion chamber, a waste heat boiler, a quench tower, a bag-type dust collector, a precooler, a two-stage washing tower, a flue gas whitening device, a chimney and a circulating water tank, wherein the secondary combustion chamber comprises an input end and a flue gas output end, the input end of the secondary combustion chamber comprises a natural gas input end, a pyrolysis gas input end and an ammonia water input end, the natural gas input end is connected with natural gas, natural gas can be input into a secondary combustion chamber through the natural gas input end, the pyrolysis gas input end of the secondary combustion chamber is connected with pyrolysis waste gas of a pyrolysis furnace, the ammonia water input end is connected with ammonia water, and ammonia water can be input into the secondary combustion chamber through the;
the input end of the waste heat boiler comprises a soft water input end and a smoke input end, the output end of the waste heat boiler comprises a steam output end and a smoke output end, the smoke input end of the waste heat boiler is connected with the smoke output end of the secondary combustion chamber, the soft water input end of the waste heat boiler is connected with soft water, soft water can be input into the waste heat boiler through the soft water input end, and the steam output end of the waste heat boiler is connected with the smoke whitening device;
the input end of the quenching tower comprises a flue gas input end and a quenching agent input end, the flue gas input end of the quenching tower is connected with the flue gas output end of the waste heat boiler, the quenching agent input end is connected with the quenching agent, the quenching agent can be input into the quenching tower through the quenching agent input end, the output end of the quenching tower is connected with the input end of the bag-type dust remover, an active carbon input end is arranged on a pipeline between the output end of the quenching tower and the bag-type dust remover, active carbon can be input into the pipeline between the output end of the quenching tower and the bag-type dust remover through the active carbon input end, the output end of the bag-type dust remover is connected with the input end of a precooler, and the output end of the precooler is connected;
the output end of the two-stage washing tower comprises a waste water output end and a flue gas output end, the waste water output end of the two-stage washing tower is respectively connected with the input end of the circulating water tank, the flue gas output end of the two-stage washing tower is connected with the input end of the flue gas whitening device, the output end of the flue gas whitening device is connected with the input end of the chimney, and the output end of the chimney can output flue gas which reaches the standard and is discharged;
the output end of the circulating water tank is connected with the input end of the two-stage washing tower, the circulating water tank can input alkali liquor into the two-stage washing tower, and the two-stage washing tower can remove pollutants in the flue gas to reach the emission standard.
2. The tail gas treatment system for the resource treatment of waste salt according to claim 1, characterized in that: the scrubber tower is a wet scrubber tower capable of removing acid gases.
3. The tail gas treatment system for the resource treatment of waste salt according to claim 1, characterized in that: the heating temperature in the secondary chamber is more than 1100 ℃, and the pyrolysis waste gas of the pyrolysis furnace stays in the secondary chamber for more than 2 seconds.
4. The tail gas treatment system for the resource treatment of waste salt according to claim 1, characterized in that: the quenching tower is a spray quenching tower, the quenching agent adopts lime water, and the retention time of the flue gas in the quenching tower is less than 1 s.
5. The tail gas treatment system for the resource treatment of waste salt according to claim 1, characterized in that: the bag-type dust collector selects a high-temperature-resistant material, and the temperature of tail gas entering the bag is controlled to be 220 +/-5 ℃;
or the quenching tower is a semi-dry quenching tower.
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