CN113154395A - COD removing system for waste water cracking and burning - Google Patents
COD removing system for waste water cracking and burning Download PDFInfo
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- CN113154395A CN113154395A CN202110341950.0A CN202110341950A CN113154395A CN 113154395 A CN113154395 A CN 113154395A CN 202110341950 A CN202110341950 A CN 202110341950A CN 113154395 A CN113154395 A CN 113154395A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
- F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/44—Details; Accessories
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- 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
- F23G7/04—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste liquors, e.g. sulfite liquors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
- F23J15/04—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material using washing fluids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E20/30—Technologies for a more efficient combustion or heat usage
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Abstract
The invention discloses a waste water cracking incineration COD removal system, which is characterized in that industrial waste water containing COD is conveyed to a heat exchange subsystem through a waste water conveying subsystem, the industrial waste water is preheated through the heat exchange subsystem, the preheated industrial waste water enters a high-temperature cracking reactor subsystem for secondary heating cracking, fog drops of the waste water are subjected to cracking reaction to generate carbon dioxide, water and other compounds, the COD is reduced to a required index, the treated waste water is collected and then enters the next process section, the carbon dioxide and the other compounds enter the heat exchange subsystem to realize waste heat recovery, flue gas passing through the heat exchange subsystem enters a flue gas subsystem, the flue gas is washed to reach the standard and then is discharged to the atmosphere, and washing waste water enters a common sewage treatment system. Therefore, the invention can remove the COD of the industrial wastewater by over 99 percent, can realize that the COD in the industrial wastewater is less than or equal to 50mg/L, and meets the discharge standard and the technical requirements of other links of wastewater treatment.
Description
Technical Field
The invention relates to the technical field of wastewater environment-friendly treatment, in particular to a system for removing COD (chemical oxygen demand) by cracking and burning wastewater.
Background
With the rapid development of economy in China, the industrial construction is greatly improved, but the industrial wastewater generated in the production process is increased day by day, so that the problem of environmental pollution is increasingly serious. The requirements of relevant environmental protection policies are increasingly strict, and involved industrial enterprises need to deeply treat industrial wastewater generated by the industrial enterprises, and even finally realize zero discharge of the wastewater.
For the wastewater treatment, the treatment mode mainly comprises a physical adsorption method and a membrane separation method, and if the treatment mode mainly comprises a Fenton oxidation method, a coagulation method, an ozone oxidation method and a photocatalytic oxidation method according to chemical reaction, the biological purification treatment can be further carried out.
However, at present, the COD concentration of part of industrial wastewater is very high. The conventional schemes are not suitable for treating COD, and even if the treatment is carried out by the method, the standard discharge is difficult; and the high-concentration COD has great influence on other treatment process processes of the wastewater, such as a multi-effect evaporation system, the serious scaling of equipment pipelines can be caused, and the system can not run normally.
Therefore, in order to solve the problem of the wastewater, the industry needs to find a high-efficiency COD removal process technology for the wastewater.
Disclosure of Invention
The invention aims to solve the technical problems and provides a system for removing COD (chemical oxygen demand) by cracking and burning waste water, wherein the removal rate of the COD can reach more than 99 percent, the COD in industrial waste water can be less than or equal to 50mg/L, and the technical requirements of discharge standards and other links of waste water treatment are met.
The technical scheme of the invention is as follows:
the COD removing system for waste water cracking incineration is characterized in that: comprises a wastewater conveying subsystem, a pyrolysis reactor subsystem, a flue gas subsystem and a heat exchange subsystem;
the treatment process for removing COD through each subsystem comprises the following steps: the waste water conveying subsystem conveys the industrial waste water containing high-concentration COD to the heat exchange subsystem, and the industrial waste water is preheated by the heat exchange subsystem; the preheated industrial wastewater enters a high-temperature cracking reactor subsystem, the industrial wastewater is sprayed in the high-temperature cracking reactor subsystem, sprayed wastewater fog drops are fully contacted with high-temperature flue gas generated by combustion of natural gas, the wastewater fog drops are instantly in a boiling state to start cracking reaction, and products after the wastewater fog drop cracking reaction comprise carbon dioxide, water and other compounds; wherein, the COD of the produced water is reduced to the required index, and the collected water can enter the next process section; the generated carbon dioxide and other compounds enter the heat exchange subsystem to heat the water vapor, hot water and industrial wastewater of the heat exchange subsystem, so that the waste heat is recovered; after heat exchange, the flue gas of the heat exchange subsystem enters the flue gas subsystem, after the flue gas subsystem is washed, the flue gas reaching the standard is discharged to the atmosphere, and the washing wastewater enters the sewage treatment system.
In the above treatment process, the specific process of the cleavage reaction is as follows:
1) under the action of high-temperature flue gas generated by natural gas combustion, water in the wastewater fog drops with high-concentration COD is instantly atomized into water vapor, organic matter components in the wastewater fog drops with high-concentration COD are gasified, the water vapor and gasified organic matter exchange heat with the high-temperature flue gas fully, and the temperature is greatly increased;
2) under the action of high-temperature flue gas generated by burning natural gas, the wastewater fog drops are heated to a temperature below the boiling point, organic matters in the wastewater fog drops are volatilized and separated out into the high-temperature flue gas, and then the high-temperature flue gas is used for heating and raising the temperature;
3) under the action of high-temperature flue gas generated by burning natural gas, the temperature is continuously increased, the steam and the gasified organic matters are continuously heated and increased, when the temperature is increased to the cracking temperature of the organic matters, the organic matters undergo cracking reaction, and the final products are steam, carbon dioxide and other simple compounds; the cracking temperature is greater than 750 ℃.
Further, the wastewater conveying subsystem for the above-mentioned wastewater cracking incineration removal COD system at least comprises: the system comprises a wastewater buffer tank, a wastewater conveying pipeline, a NaOH solution adding device, a wastewater booster pump, a flowmeter and matched pipelines; the waste water buffer tank is connected with a waste water conveying pipeline and a NaOH solution adding device, and then waste water is pumped into the heat exchange subsystem through a waste water booster pump and a pipeline; industrial wastewater in a plant area enters a wastewater buffer tank through a wastewater conveying pipeline for storage, NaOH solution is added through a NaOH solution adding device for conditioning, the conditioned wastewater is alkalescent (namely the pH is less than or equal to 8), and the wastewater is conveyed into a heat exchange subsystem through a wastewater booster pump combined pipeline.
Further, the pyrolysis reactor subsystem for the above-mentioned waste water cracking incineration removal COD system at least comprises: the device comprises a two-stage pyrolysis reactor, a wastewater spray pump, a wastewater delivery pump and matched pipelines; wherein, the waste water sprays the pump and connects in the bottom outside of first order pyrolysis reactor, and the pump delivery line of waste water spraying pump includes two the tunnel, inserts the industrial waste water input pipeline at first order pyrolysis reactor top all the way, and another way is as the waste water input pipeline at second order pyrolysis reactor top, and the waste water delivery pump is connected in the bottom outside of second order pyrolysis reactor.
The high-temperature cracking reactor takes high-temperature flue gas generated by burning natural gas as a cracking heat source. The fine waste water droplets are fully contacted with high-temperature flue gas generated by the combustion of natural gas, so that the micro fog droplets are instantly in a boiling state, and the organic matters are quickly and effectively cracked.
The high-temperature cracking reactors are all in a counter-flow mode, the fog drops of the wastewater form a flow direction from top to bottom through spraying, and the high-temperature flue gas flows from bottom to top. Therefore, the flow direction of the waste water fog drops is opposite to that of the high-temperature flue gas, the heat exchange efficiency can be improved, the residence time of the fog drops is prolonged, and the cracking effect is ensured.
In the high-temperature cracking reactor, a part of organic matters discharged by heating and cracking contacts with high-temperature flue gas, and the organic matters are generated by combustion oxidation reaction, so that certain heat can be released, and the organic matter removal process can be further promoted.
In the first-stage high-temperature cracking reactor, after most of organic matters and COD of the heated and cracked waste water are removed, the waste water is collected in a bottom water tank, and then is sent to the second-stage cracking reactor by a waste water spraying pump to further deepen the cracking of the organic matters, so that the COD in the waste water is reduced to within a design value.
At the starting stage of the pyrolysis reactor or under the working condition that the COD value in the wastewater is abnormally high, the wastewater spray pump can circularly convey the wastewater in the bottom water tank of the first-stage pyrolysis reactor back to the top of the first-stage pyrolysis reactor, and the wastewater is sprayed again to carry out the pyrolysis process until the COD concentration value of the wastewater in the bottom water tank of the first-stage pyrolysis reactor is within the design range, and then the wastewater is conveyed to the second-stage pyrolysis reactor.
The industrial waste water is heated and cracked in the high-temperature cracking reactor and is evaporated and concentrated at the same time. Design allowances such as a burner in the high-temperature cracking reactor can be increased according to project requirements, the water in the wastewater is completely evaporated, zero discharge of the wastewater is directly realized, and industrial salt is recovered.
Further, a flue gas subsystem for the above-mentioned waste water schizolysis burns desorption COD system includes at least: the device comprises a flue, a water washing tower, an exhaust fan, a spraying circulating pump, a flowmeter, a chimney and matched pipelines; high-temperature flue gas from the first-stage high-temperature cracking reactor is introduced into the second-stage high-temperature cracking reactor through a flue, and is converged with high-temperature flue gas generated by combustion of natural gas in the second-stage high-temperature cracking reactor to be jointly used for heating cracking wastewater droplets, so that organic combustible flue gas in the high-temperature flue gas of the first-stage high-temperature cracking reactor is fully combusted, pollutant discharge is reduced, certain heat is obtained, and cracking reaction is promoted; the high-temperature flue gas from the second-stage high-temperature cracking reactor is cooled by the heat exchange subsystem, so that waste heat is recovered and then is introduced to the water washing tower; in order to prevent the pollutants possibly remained in the flue gas from polluting the environment, the flue gas is purified by the water washing tower, and the cleaned flue gas after washing is discharged from the top of the water washing tower and is exhausted to the atmosphere through an exhaust fan and a chimney.
The water washing tower can adopt a counter-flow type spray tower, flue gas enters from a connector at the middle lower part of the water washing tower, the flue gas flows from bottom to top, spray fog drops which drop from top to bottom are arranged in the middle-upper area in the water washing tower, the flue gas can be sufficiently washed, and a small amount of residual pollutants in the flue gas can be removed.
And the top of the water washing tower is provided with a high-efficiency demister for removing spray mist drops in the flue gas.
The washing tower is provided with a water replenishing valve and a water discharging valve, and water in the bottom pool of the washing tower is in a normal water level range through mutual matching and adjustment.
Further, a heat exchange subsystem for above-mentioned waste water schizolysis burns desorption COD system includes at least: the system comprises a steam generator, a hot water heater, a waste water preheater, a hot water header, a hot water booster pump, a flowmeter and a matched pipeline; flue gas exhausted by the high-temperature cracking reactor subsystem enters a heat exchange subsystem, passes through a steam generator, a hot water heater and a waste water preheater in sequence and heats steam, hot water and industrial waste water of the heat exchange subsystem; the waste water input of the waste water preheater is pumped into industrial waste water by a waste water booster pump of a waste water conveying subsystem, and the waste water output of the waste water preheater is connected with an industrial waste water input pipeline at the top of the first-stage cracking reactor; the hot water booster pump pumps hot return water into the hot water heater from the hot water header tank, the hot return water is heated to more than 90 ℃ by the hot water heater by using a low-grade flue gas heat source, the heated hot return water is divided into two paths, one path is used by a hot water user, and the other path enters the steam generator; and a part of hot water is further heated and evaporated by a steam generator and a high-grade flue gas heat source to prepare superheated steam, and the superheated steam is supplied to steam users for use through pipelines.
In the heat exchange subsystem, the initial industrial wastewater is raised from normal temperature to more than 70 ℃ through a wastewater preheater and then is sprayed into the first-stage pyrolysis reactor, and meanwhile, the temperature of the flue gas is reduced to about 60 ℃, so that the final waste heat of the flue gas is fully utilized.
The invention has the following technical effects:
1. the reasonable waste water conveying subsystem is designed, industrial waste water in a plant area is pumped into the heat exchange subsystem, different tastes of regenerative heat are generated according to the heat source conditions of the flue gas, the heat exchange subsystem can effectively utilize high-grade flue gas and low-grade flue gas, the waste heat of the flue gas is fully recycled, and the use requirements of different heat users can be met.
2. The invention carries out the heating cracking treatment on the industrial wastewater, carries out organic matter removal on the industrial wastewater through the secondary heating cracking, reduces the concentration of COD, and can effectively treat the high-concentration COD wastewater into steam, carbon dioxide and other simple compounds, thereby realizing the purpose of wastewater treatment.
3. The process structure of the invention has reasonable design, good technology and high economical efficiency.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The technical scheme of the invention is designed by combining the drawings in the specification and further implemented as follows.
The system for removing COD by cracking and incinerating wastewater as shown in figure 1 comprises a wastewater conveying subsystem, a high-temperature cracking reactor subsystem, a flue gas subsystem and a heat exchange subsystem.
The treatment process for removing COD through each subsystem comprises the following steps: the waste water conveying subsystem conveys the industrial waste water containing high-concentration COD to the heat exchange subsystem, and the industrial waste water is preheated by the heat exchange subsystem; the preheated industrial wastewater enters a high-temperature cracking reactor subsystem, the industrial wastewater is sprayed in the high-temperature cracking reactor subsystem, sprayed wastewater fog drops are fully contacted with high-temperature flue gas generated by combustion of natural gas, the wastewater fog drops are instantly in a boiling state to start cracking reaction, and products after the wastewater fog drop cracking reaction comprise carbon dioxide, water and other compounds.
In the production of the product: the COD of the water is reduced to the required index, and the water can enter the next process section after being collected; the generated carbon dioxide and other compounds enter the heat exchange subsystem to heat the water vapor, hot water and industrial wastewater of the heat exchange subsystem, so that the waste heat is recovered; after heat exchange, the flue gas of the heat exchange subsystem enters the flue gas subsystem, after the flue gas subsystem is washed, the flue gas reaching the standard is discharged to the atmosphere, and the washing wastewater enters the sewage treatment system.
In the above treatment process, the specific process of the cleavage reaction is as follows:
1) under the action of high-temperature flue gas generated by natural gas combustion, water in the wastewater fog drops with high-concentration COD is instantly atomized into water vapor, organic matter components in the wastewater fog drops with high-concentration COD are gasified, the water vapor and gasified organic matter exchange heat with the high-temperature flue gas fully, and the temperature is greatly increased;
2) under the action of high-temperature flue gas generated by burning natural gas, the wastewater fog drops are heated to a temperature below the boiling point, organic matters in the wastewater fog drops are volatilized and separated out into the high-temperature flue gas, and then the high-temperature flue gas is used for heating and raising the temperature;
3) under the action of high-temperature flue gas generated by burning natural gas, the temperature is continuously increased, the steam and the gasified organic matters are continuously heated and increased, when the temperature is increased to the cracking temperature of the organic matters, the organic matters undergo cracking reaction, and the final products are steam, carbon dioxide and other simple compounds; the cracking temperature is greater than 750 ℃.
In the cracking reaction process, the heat released by the organic matters can be used for heating flue gas.
In the cracking reaction process, after the fog drops of the wastewater are heated and cracked, organic matters are removed to reduce COD, and after the COD is reduced to a required index, the COD is collected and enters the next process section.
After the cracking reaction process, the flue gas is discharged from the high-temperature cracking reactor subsystem, enters the heat exchange subsystem, is used for fully recovering waste heat of water vapor, hot water and industrial wastewater of the heat exchange subsystem, and is discharged to the atmosphere through a washing tower chimney.
Further, the wastewater conveying subsystem for the above-mentioned wastewater cracking incineration removal COD system at least comprises: the system comprises a wastewater buffer tank, a wastewater conveying pipeline, a NaOH solution adding device, a wastewater booster pump, a flowmeter and matched pipelines; the waste water buffer tank is connected with a waste water conveying pipeline and a NaOH solution adding device, and then waste water is pumped into the heat exchange subsystem through a waste water booster pump and a pipeline; industrial wastewater in a plant area enters a wastewater buffer tank through a wastewater conveying pipeline for storage, NaOH solution is added through a NaOH solution adding device for conditioning, the conditioned wastewater is alkalescent (namely the pH is less than or equal to 8), and the wastewater is conveyed into a heat exchange subsystem through a wastewater booster pump combined pipeline.
The wastewater booster pump controls the pressure of a wastewater output pipeline and the amount of wastewater sent to the high-temperature cracking reactor subsystem through frequency conversion; the waste water booster pump can be provided with two pumps, one pump is operated, and the other pump is standby.
Further, the pyrolysis reactor subsystem for the above-mentioned waste water cracking incineration removal COD system at least comprises: the device comprises a two-stage pyrolysis reactor, a wastewater spray pump, a wastewater delivery pump and matched pipelines; wherein, the waste water sprays the pump and connects in the bottom outside of first order pyrolysis reactor, and the pump delivery line of waste water spraying pump includes two the tunnel, inserts the industrial waste water input pipeline at first order pyrolysis reactor top all the way, and another way is as the waste water input pipeline at second order pyrolysis reactor top, and the waste water delivery pump is connected in the bottom outside of second order pyrolysis reactor.
The high-temperature cracking reactor takes high-temperature flue gas generated by burning natural gas as a cracking heat source. The fine waste water droplets are fully contacted with high-temperature flue gas generated by the combustion of natural gas, so that the micro fog droplets are instantly in a boiling state, and the organic matters are quickly and effectively cracked.
The high-temperature cracking reactors are all in a counter-flow mode, the fog drops of the wastewater form a flow direction from top to bottom through spraying, and the high-temperature flue gas flows from bottom to top. Therefore, the flow direction of the waste water fog drops is opposite to that of the high-temperature flue gas, the heat exchange efficiency can be improved, the residence time of the fog drops is prolonged, and the cracking effect is ensured.
In the high-temperature cracking reactor, a part of organic matters discharged by heating and cracking contacts with high-temperature flue gas, and the organic matters are generated by combustion oxidation reaction, so that certain heat can be released, and the organic matter removal process can be further promoted.
In the first-stage high-temperature cracking reactor, after most of organic matters and COD of the heated and cracked waste water are removed, the waste water is collected in a bottom water tank, and then is sent to the second-stage cracking reactor by a waste water spraying pump to further deepen the cracking of the organic matters, so that the COD in the waste water is reduced to within a design value.
At the starting stage of the pyrolysis reactor or under the working condition that the COD value in the wastewater is abnormally high, the wastewater spray pump can circularly convey the wastewater in the bottom water tank of the first-stage pyrolysis reactor back to the top of the first-stage pyrolysis reactor, and the wastewater is sprayed again to carry out the pyrolysis process until the COD concentration value of the wastewater in the bottom water tank of the first-stage pyrolysis reactor is within the design range, and then the wastewater is conveyed to the second-stage pyrolysis reactor.
The industrial waste water is heated and cracked in the high-temperature cracking reactor and is evaporated and concentrated at the same time. Design allowances such as a burner in the high-temperature cracking reactor can be increased according to project requirements, the water in the wastewater is completely evaporated, zero discharge of the wastewater is directly realized, and industrial salt is recovered.
The waste water spray pump can be provided with two pumps, one pump runs and the other pump is standby.
Further, a flue gas subsystem for the above-mentioned waste water schizolysis burns desorption COD system includes at least: the device comprises a flue, a water washing tower, an exhaust fan, a spraying circulating pump, a flowmeter, a chimney and matched pipelines; high-temperature flue gas from the first-stage high-temperature cracking reactor is introduced into the second-stage high-temperature cracking reactor through a flue, and is converged with high-temperature flue gas generated by combustion of natural gas in the second-stage high-temperature cracking reactor to be jointly used for heating cracking wastewater droplets, so that organic combustible flue gas in the high-temperature flue gas of the first-stage high-temperature cracking reactor is fully combusted, pollutant discharge is reduced, certain heat is obtained, and cracking reaction is promoted; the high-temperature flue gas from the second-stage high-temperature cracking reactor is cooled by the heat exchange subsystem, so that waste heat is recovered and then is introduced to the water washing tower; in order to prevent the pollutants possibly remained in the flue gas from polluting the environment, the flue gas is purified by the water washing tower, and the cleaned flue gas after washing is discharged from the top of the water washing tower and is exhausted to the atmosphere through an exhaust fan and a chimney.
The water washing tower can adopt a counter-flow type spray tower, flue gas enters from a connector at the middle lower part of the water washing tower, the flue gas flows from bottom to top, spray fog drops which drop from top to bottom are arranged in the middle-upper area in the water washing tower, the flue gas can be sufficiently washed, and a small amount of residual pollutants in the flue gas can be removed.
And the top of the water washing tower is provided with a high-efficiency demister for removing spray mist drops in the flue gas.
The washing tower can be provided with two spraying circulating pumps and corresponding spraying layers, and each spraying layer is correspondingly and independently supplied with slurry by one spraying circulating pump.
The water replenishing in the bottom pool of the washing tower is introduced into raw water provided by a plant pipe network through a pipeline, such as common industrial water, and the raw water is filtered and then injected into the washing tower.
The water in the bottom pool of the washing tower contains a small amount of pollutants, belongs to common sewage and is discharged to a factory sewage treatment system.
The water replenishing pipeline of the washing tower is provided with a water replenishing valve, the sewage discharge pipeline of the bottom tank is provided with a water discharge valve, and the water in the bottom tank of the washing tower is in a normal water level range through mutual matching adjustment.
The inlet flue of the washing tower is provided with an accident temperature-reducing water spraying system, and the washing tower can be put into operation immediately under the accident working condition, so that high-temperature smoke is prevented from damaging the washing tower and downstream equipment facilities.
The resistance of the flue gas subsystem is overcome by an exhaust fan behind the water washing tower, and the exhaust fan is made of PP or glass fiber reinforced plastic materials.
Further, a heat exchange subsystem for above-mentioned waste water schizolysis burns desorption COD system includes at least: the system comprises a steam generator, a hot water heater, a waste water preheater, a hot water header, a hot water booster pump, a flowmeter and a matched pipeline; flue gas exhausted by the high-temperature cracking reactor subsystem enters a heat exchange subsystem, passes through a steam generator, a hot water heater and a waste water preheater in sequence and heats steam, hot water and industrial waste water of the heat exchange subsystem; the waste water input of the waste water preheater is pumped into industrial waste water by a waste water booster pump of a waste water conveying subsystem, and the waste water output of the waste water preheater is connected with an industrial waste water input pipeline at the top of the first-stage cracking reactor; the hot water booster pump pumps hot return water into the hot water heater from the hot water header tank, the hot return water is heated to more than 90 ℃ by the hot water heater by using a low-grade flue gas heat source, the heated hot return water is divided into two paths, one path is used by a hot water user, and the other path enters the steam generator; by using a steam generator and a high-grade flue gas heat source, part of hot water is further heated and evaporated to prepare superheated steam (the parameters of the steam are undetermined and can be consistent with the existing heat supply steam in a plant area), and the superheated steam is supplied to steam users for use through a pipeline.
In the heat exchange subsystem, the initial industrial wastewater is raised from normal temperature to more than 70 ℃ through a wastewater preheater and then is sprayed into the first-stage pyrolysis reactor, and meanwhile, the temperature of the flue gas is reduced to about 60 ℃, so that the final waste heat of the flue gas is fully utilized.
The waste water cracking and burning COD removing system is also particularly suitable for industrial waste water with COD more than 50 mg/L.
Claims (10)
1. The COD removing system for waste water cracking incineration is characterized in that: comprises a wastewater conveying subsystem, a pyrolysis reactor subsystem, a flue gas subsystem and a heat exchange subsystem; the treatment process for removing COD through each subsystem comprises the following steps:
(1) the waste water conveying subsystem conveys the industrial waste water containing COD to the heat exchange subsystem, and the industrial waste water is preheated by the heat exchange subsystem;
(2) the preheated industrial wastewater enters a high-temperature cracking reactor subsystem, the industrial wastewater is sprayed into wastewater fog drops in the high-temperature cracking reactor subsystem, the wastewater fog drops are fully contacted with flue gas generated by combustion of natural gas, the wastewater fog drops are instantly in a boiling state to start cracking reaction, and products after the wastewater fog drop cracking reaction comprise carbon dioxide, water and other compounds;
the COD of the generated water is reduced to the required index, and the water enters the next process section after being collected;
the generated carbon dioxide and other compounds enter the heat exchange subsystem and are used for heating water vapor, hot water and industrial wastewater of the heat exchange subsystem to realize waste heat recovery;
the flue gas passing through the heat exchange subsystem enters a flue gas subsystem, the flue gas reaching the standard is discharged to the atmosphere after being washed by the flue gas subsystem, and the washing wastewater enters a sewage treatment system.
2. The system for removing COD by cracking and incinerating wastewater according to claim 1, wherein the specific process of the cracking reaction is as follows:
1) under the action of flue gas generated by natural gas combustion, water in the waste water fog drops is instantly atomized into steam, organic matter components in the waste water fog drops are gasified, the steam and the gasified organic matter exchange heat with the flue gas fully, and the temperature is increased;
2) under the action of flue gas generated by natural gas combustion, the wastewater fog drops are heated to a temperature below the boiling point, and organic matters in the wastewater fog drops are volatilized and separated out to the flue gas and are heated to raise the temperature;
3) under the action of high-temperature flue gas, the temperature is continuously increased, the steam and the gasified organic matters are continuously heated and increased, when the temperature is increased to the cracking temperature of the organic matters, the organic matters undergo cracking reaction, and the final products are steam, carbon dioxide and other compounds; the cracking temperature is more than 750 ℃;
in the cracking reaction process, the organic matters release heat to heat flue gas.
3. The system for removing COD by cracking and incinerating wastewater as claimed in claim 1 or 2, wherein the wastewater conveying subsystem at least comprises a wastewater buffer tank, a wastewater conveying pipeline, a NaOH solution adding device, a wastewater booster pump and a matched pipeline; the waste water buffer tank is connected with a waste water conveying pipeline and a NaOH solution adding device, and then waste water is pumped into the heat exchange subsystem through a waste water booster pump and a pipeline; industrial wastewater enters a wastewater buffer tank through a wastewater conveying pipeline for storage, NaOH solution is added through a NaOH solution adding device for tempering, the modulated wastewater is alkalescent, and the wastewater is conveyed to a heat exchange subsystem through a wastewater booster pump combined pipeline.
4. The system for removing COD by cracking and incinerating wastewater according to claim 3, is characterized in that: and the wastewater booster pump controls the pressure of a wastewater output pipeline and the amount of wastewater sent into the high-temperature cracking reactor subsystem through frequency conversion.
5. The system for removing COD by cracking and incinerating wastewater according to claim 1 or 2, which is characterized in that: the pyrolysis reactor sub-system comprising at least: the device comprises a two-stage pyrolysis reactor, a wastewater spray pump, a wastewater delivery pump and matched pipelines; the system comprises a first-stage cracking reactor, a waste water spraying pump, a pump-out pipeline, a waste water conveying pump and a waste water storage tank, wherein the waste water spraying pump is connected to the outer side of the bottom of the first-stage cracking reactor;
in the first-stage high-temperature cracking reactor, after organic matters and COD (chemical oxygen demand) of heated and cracked wastewater fog drops are removed, the wastewater fog drops are collected in a bottom water tank and then are sent to a second-stage cracking reactor by a wastewater spray pump to further crack the organic matters, so that the COD in the wastewater is reduced to be within a design value; at the starting stage of the pyrolysis reactor or under the working condition that the COD value in the wastewater is abnormally high, the wastewater in the water tank at the bottom of the first-stage pyrolysis reactor is circularly conveyed back to the top of the first-stage pyrolysis reactor by the wastewater spray pump, sprayed again, subjected to the pyrolysis process until the COD concentration value of the wastewater in the water tank at the bottom of the first-stage pyrolysis reactor is within the design range, and conveyed to the second-stage pyrolysis reactor.
6. The system for removing COD by cracking and incinerating wastewater according to claim 5, is characterized in that: the high-temperature cracking reactors are all in a counter-flow mode, the fog drops of the wastewater form a flow direction from top to bottom through spraying, and the high-temperature flue gas flows from bottom to top.
7. The system for removing COD by cracking and incinerating wastewater according to claim 1 or 2, which is characterized in that: the flue gas subsystem at least comprises a flue, a water washing tower, an exhaust fan, a spraying circulating pump, a flowmeter, a chimney and a matched pipeline; the flue gas from the first-stage high-temperature cracking reactor is introduced into a second-stage high-temperature cracking reactor through a flue, and is converged with the flue gas generated by burning of second-stage natural gas to be jointly used for heating the fog drops of cracking wastewater, so that organic combustible flue gas in the first-stage high-temperature cracking reactor is fully burnt, and heat is obtained to promote cracking reaction; the flue gas from the second-stage high-temperature cracking reactor is cooled by the heat exchange subsystem, and is introduced to the water washing tower after waste heat recovery is realized; the flue gas is purified by the water washing tower, and the cleaned flue gas is discharged from the top of the water washing tower and is exhausted to the atmosphere through an exhaust fan and a chimney.
8. The system for removing COD by cracking and incinerating wastewater according to claim 7, is characterized in that: the water washing tower adopts a counter-flow type spray tower, flue gas enters from a connector at the middle lower part of the water washing tower, the flue gas flows from bottom to top, spray fog drops which drop from top to bottom are arranged in the middle-upper area inside the water washing tower, and the spray fog drops fully wash the flue gas to remove residual pollutants in the flue gas; the top of the water washing tower is provided with a demister for removing spray mist drops in the flue gas; the water replenishing pipeline of the washing tower is provided with a water replenishing valve, the sewage discharge pipeline of the bottom tank is provided with a water discharge valve, and the water in the bottom tank of the washing tower is in a normal water level range through mutual matching adjustment.
9. The system for removing COD by cracking and incinerating wastewater according to claim 1 or 2, which is characterized in that: the heat exchange subsystem comprises a steam generator, a hot water heater, a waste water preheater, a hot water header tank, a hot water booster pump, a flowmeter and a matched pipeline; flue gas exhausted by the high-temperature cracking reactor subsystem enters a heat exchange subsystem, passes through a steam generator, a hot water heater and a waste water preheater in sequence and heats steam, hot water and industrial waste water of the heat exchange subsystem; the waste water input of the waste water preheater is pumped into industrial waste water by a waste water booster pump of a waste water conveying subsystem, and the waste water output of the waste water preheater is connected with an industrial waste water input pipeline at the top of the first-stage cracking reactor; the hot water booster pump pumps hot return water into the hot water heater from the hot water header tank, the hot return water is heated to more than 90 ℃ by the hot water heater by using a low-grade flue gas heat source, the heated hot return water is divided into two paths, one path is used by a hot water user, and the other path enters the steam generator; and a part of hot water is further heated and evaporated by a steam generator and a high-grade flue gas heat source to prepare superheated steam, and the superheated steam is supplied to steam users for use through pipelines.
10. The system for removing COD by cracking and incinerating wastewater according to claim 1 or 2, which is characterized in that: the waste water cracking, burning and COD removing system is at least suitable for industrial waste water with COD more than 50 mg/L.
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