CN114377509A - Method and system for treating low-temperature pyrolysis tail gas - Google Patents
Method and system for treating low-temperature pyrolysis tail gas Download PDFInfo
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- CN114377509A CN114377509A CN202210051574.6A CN202210051574A CN114377509A CN 114377509 A CN114377509 A CN 114377509A CN 202210051574 A CN202210051574 A CN 202210051574A CN 114377509 A CN114377509 A CN 114377509A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/16—Treatment of water, waste water, or sewage by heating by distillation or evaporation using waste heat from other processes
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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
- F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
Abstract
The invention relates to the technical field of pyrolysis, and discloses a method and a system for treating low-temperature pyrolysis tail gas, wherein first tail gas generated by pyrolysis in a pyrolysis furnace is condensed by a first condenser and then is introduced into a secondary combustion chamber for secondary combustion; wherein, the comdenstion water that produces when condensing first tail gas lets in the evaporation pond, and the comdenstion water in the evaporation pond is evaporated to the waste heat of the second tail gas that utilizes the afterburning to produce, and the water in the comdenstion water becomes steam, separates with tar to make tar stay in the evaporation pond, realize the processing to the comdenstion water, and need not to increase extra cost, and realized the zero release. And finally, the third tail gas discharged from the second condenser is discharged after being introduced into a dust remover for dust removal, wherein the waste heat of the second tail gas is utilized to heat a pipeline between the second condenser and the dust remover, and the dust remover can be prevented from being stuck with bags.
Description
Technical Field
The invention relates to the technical field of pyrolysis, in particular to a method and a system for treating low-temperature pyrolysis tail gas.
Background
The pyrolysis technology is a process of heating at high temperature in an oxygen-free or oxygen-deficient environment, driving organic matters to carry out thermal cracking and thermochemical reaction by utilizing complex endothermic and exothermic reactions, changing the original molecular structure and converting the organic matters into different phase state hydrocarbons, wherein products comprise carbon, oil, water, micromolecular water-soluble organic matters and non-condensable gases. It is a complex reaction process, including primary cracking, secondary cracking, various complex reaction processes between carbon and various gaseous products and gases. The organic solid waste high-volatile material is suitable for anaerobic pyrolysis technology, such as dried sludge, oil sludge, kitchen waste, biomass and the like.
In the organic solid waste treatment field, especially low temperature pyrolysis subdivision field, the pyrolysis oven (gasification burner) can produce a large amount of tar and gaseous water at the pyrolysis in-process, and these tar and gaseous water can be along with the flue gas discharge pyrolysis oven, and gaseous water concentration in the flue gas is big more can influence follow-up postcombustion's going on smoothly to and can increase postcombustion's energy supply. For better energy saving, the secondary combustion flue gas is condensed to remove water, but the condensed water generated after condensation contains not only pollution-free water but also tar, inorganic compounds and the like, and the tar, the inorganic compounds and the like finally form a polluted mechanical mixture (suspension) with water, so that the water cannot be directly discharged and needs to be sent to other dangerous wastewater treatment enterprises for further treatment and then discharged, but if the condensed water is treated by other dangerous wastewater treatment enterprises, the treatment turnover flow and the treatment cost are increased, and the cost is high.
The prior art discloses a sludge treatment device integrating condensation dehydration and waste heat utilization and a process flow, the device comprises a magnetization pyrolysis machine, a dehumidification tower, a heat exchanger, a secondary combustion chamber and a tail gas treatment device which are sequentially connected, a flue gas outlet of the magnetization pyrolysis machine is connected with a flue gas inlet of the dehumidification tower, a flue gas outlet of the dehumidification tower is connected with a flue gas inlet of the heat exchanger, a flue gas outlet of the heat exchanger is communicated with the magnetization pyrolysis machine through a flue and is communicated with a flue gas inlet of the secondary combustion chamber through another flue, and a flue gas outlet of the secondary combustion chamber is connected with the tail gas treatment device after being subjected to thermal circulation through the heat exchanger; the process flow is that sludge with high water content is subjected to magnetization pyrolysis, hydration and gasification by a magnetization pyrolysis machine, slag can be discharged from a slag outlet, flue gas containing a large amount of water vapor enters a spray type dehumidification tower, part of dewatered dry flue gas enters a heat exchanger and then returns to the magnetization pyrolysis machine for further incineration, part of the dewatered dry flue gas enters a secondary combustion chamber so that combustible gas and harmful substances are completely combusted and incinerated, high-temperature flue gas output by the secondary combustion chamber passes through the heat exchanger to exchange heat with the part of flue gas entering the pyrolysis machine, and finally the flue gas passes through a water-cooled heat exchanger, a powder spraying device, a bag-type dust collector and a chimney to achieve standard emission. It can be known that, in this patent, the high moisture flue gas of high temperature that discharges from the pyrolysis machine gets into spray dehumidification tower, and the dry flue gas after the dehumidification gets into heat exchanger after, through the combustion chamber burning of two combustion chambers again, however, the water that this patent separated in spray dehumidification tower is the mechanical mixture who contains substance such as tar, inorganic compound, can not directly discharge, and the device and the system of this patent do not handle the water that separates in the spray dehumidification tower, can not directly discharge, consequently, need to be handed other danger waste water treatment enterprises and just can discharge through handling, the cost is increased.
Disclosure of Invention
The invention aims to provide a method and a system for treating low-temperature pyrolysis tail gas, which are environment-friendly and reduce the cost.
In order to achieve the purpose, the invention provides a method for treating low-temperature pyrolysis tail gas, which comprises the steps of condensing first tail gas generated by pyrolysis in a pyrolysis furnace through a first condenser, and introducing the condensed first tail gas into a secondary combustion chamber for secondary combustion; and the condensed water generated during condensation of the first tail gas is introduced into the evaporation tank, the condensed water in the evaporation tank is evaporated by using the waste heat of the second tail gas generated by secondary combustion, and the steam generated in the evaporation tank and the second tail gas are treated together.
Preferably, the steam generated by the evaporation tank and the second tail gas are rapidly cooled by a quencher primarily, cooled by a second condenser secondarily, and finally discharged after the third tail gas discharged from the second condenser is introduced into a dust remover for dust removal.
Preferably, the third tail gas is conveyed between the second condenser and the dust remover through a pipeline, and the pipeline is heated from the outside.
Preferably, a pipeline for conveying the third tail gas between the second condenser and the dust remover passes through the heating chamber, the second tail gas generated by secondary combustion is introduced into the heating chamber, the pipeline for conveying the third tail gas is heated by using the waste heat of the second tail gas, and then the second tail gas in the heating chamber is discharged to the quencher.
The invention also provides a system for treating the low-temperature pyrolysis tail gas, which comprises a pyrolysis furnace, a first condenser, a second combustion chamber and an evaporation pool, the pyrolysis furnace is provided with a smoke outlet, the first condenser is provided with a first air inlet, a first air outlet and a condensed water outlet, the second combustion chamber is provided with a second air inlet and a second air outlet, the evaporation tank is a closed tank body, the evaporation tank is provided with a water inlet and a steam outlet, the flue gas outlet is communicated with the first air inlet through a flue gas pipeline, the first air outlet is communicated with the second air inlet through a second combustion chamber inlet pipeline, the second air outlet is connected with a second combustion chamber outlet pipeline, the condensed water outlet is communicated with the water inlet through a drainage pipeline, the steam outlet is communicated with the second combustion chamber outlet pipeline through a steam pipeline, and the second combustion chamber outlet pipeline passes through the evaporation tank and exchanges heat with the evaporation tank.
As a preferred scheme, the system also comprises a quencher, a second condenser, a dust remover and a fan, wherein an outlet pipeline of the second combustion chamber, the quencher, the second condenser, the dust remover and the fan are communicated in sequence.
Preferably, a water inlet delaying device is arranged on the water discharge pipeline.
Preferably, the second condenser is communicated with the dust remover through a connecting pipeline, and a heating device is coated outside the connecting pipeline.
Preferably, the heating device comprises a heating chamber, an air inlet pipe and an air return pipe, the heating chamber is a box body, openings are arranged on two opposite sides of the heating chamber, the connecting pipeline penetrates through the heating chamber through the openings, the heating chamber is provided with an inlet and an outlet, the outlet pipeline of the secondary combustion chamber is communicated with the inlet through the air inlet pipe, and the outlet is communicated with the quencher through the air return pipe.
Preferably, the air return pipe is provided with a flow regulating valve.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the first tail gas discharged from the pyrolysis furnace is condensed by the first condenser, so that the water content of the gas entering the second combustion chamber for combustion is reduced, the smooth secondary combustion is facilitated, and the use amount of fuel is reduced. The condensed water after the condensation of the first tail gas is a mechanical mixture containing tar, inorganic compounds and the like, the condensed water is introduced into an evaporation tank, the condensed water is evaporated in the evaporation tank, wherein water is changed into steam and is separated from the tar in the condensed water, so that the tar is left in the evaporation tank, the tar can be periodically cleaned manually after being solidified, and can be put into a pyrolysis furnace again for pyrolysis, thereby realizing reutilization and reducing cost. In addition, the evaporation tank provided by the invention supplies heat by using the waste heat of the second tail gas generated by secondary combustion, so that the heat resource of the evaporation tank is fully utilized, and the additional cost is not required to be increased. Therefore, by the method and the system, the condensed water condensed from the first tail gas generated by the pyrolysis furnace can be treated without being handed to hazardous wastewater treatment enterprises for treatment, the cost is reduced, in the condensed water treatment process, the additional cost is not required to be increased, the tar in the condensed water can be recycled, and the substances discharged at the end of the whole pyrolysis process are pollution-free, environment-friendly and high in resource utilization rate.
Drawings
Fig. 1 is a flow chart of a method for treating low-temperature pyrolysis tail gas according to a first embodiment of the invention.
Fig. 2 is a flowchart of a method for treating low-temperature pyrolysis tail gas according to a second embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a third embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a fourth embodiment of the present invention.
Fig. 5 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a fifth embodiment of the present invention.
Fig. 6 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a sixth embodiment of the present invention.
Fig. 7 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a seventh embodiment of the present invention.
Fig. 8 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to an eighth embodiment of the present invention.
Fig. 9 is a schematic structural diagram of a system for processing low-temperature pyrolysis tail gas according to a ninth embodiment of the present invention.
Fig. 10 is a schematic structural diagram of a system for processing a low-temperature pyrolysis tail gas according to a tenth embodiment of the present invention.
In the figure, 1-pyrolysis furnace; 2-a first condenser; 3-a second combustion chamber; 4-an evaporation tank; 5-flue gas pipeline; 6-inlet pipeline of second combustion chamber; 7-second combustion chamber outlet pipeline; 8-a drainage pipeline; 9-a control valve; 10-a vapor line; 11-a quencher; 12-a second condenser; 13-a dust remover; 14-a fan; 15-sinking a water elbow; 16-a water feeding pipe; 17-a switching valve; 18-connecting a pipe; 19-a heating chamber; 20-entering the trachea; 21-muffler; 22-a regulating valve; 23-a gas distributor; 24-an inlet elbow; 25-return-air elbow.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
Example one
As shown in fig. 1, in the method for treating tail gas from low-temperature pyrolysis according to the preferred embodiment of the present invention, a first tail gas generated by pyrolysis in a pyrolysis furnace is condensed by a first condenser, and then introduced into a second combustion chamber for secondary combustion; and the condensed water generated during condensation of the first tail gas is introduced into the evaporation tank, the condensed water in the evaporation tank is evaporated by using the waste heat of the second tail gas generated by secondary combustion, and the steam generated in the evaporation tank and the second tail gas are treated together.
This embodiment is through first condenser to the first tail gas of pyrolysis oven exhaust condensation, reduces the water content of the gas that gets into the combustion of second combustion chamber, helps going on smoothly and reducing the use amount of fuel of postcombustion. The comdenstion water after first tail gas condensation contains tar, the mechanical mixture of inorganic compound etc, this embodiment lets in an evaporation pond with this comdenstion water, the comdenstion water evaporates in the evaporation pond, wherein, water becomes steam, separate with the tar in the comdenstion water, thereby make tar stay in the evaporation pond, treat the tar solidification, but regular manual cleaning, and can drop into the pyrolysis oven again and carry out the pyrolysis, tar gets back to the pyrolysis oven, it itself continues to carry out pyrolytic reaction, become the micromolecule material from macromolecular substance, can realize the zero release, and the conjugation of pyrolysis gas and organic solid useless has been increased, the fracture of C-C bond has been promoted, be favorable to improving pyrolysis efficiency, realize reuse, and the cost is reduced.
And the steam separated from the condensed water and the second tail gas generated by secondary combustion are treated together, so that the pollution caused by the steam separated from the condensed water is prevented, the efficiency can be improved, and the additional cost is not increased. In addition, the evaporation tank of the embodiment supplies heat by using the waste heat of the second tail gas generated by secondary combustion, so that the heat resource of the evaporation tank is fully utilized, and the additional cost is not required to be increased. Therefore, through the method of this embodiment, can handle the comdenstion water that condenses out in the first tail gas that the pyrolysis oven produced, need not to hand over by danger waste water treatment enterprise and handle, reduce cost, and at the in-process that the comdenstion water was handled, need not to increase extra cost to make tar reuse in the comdenstion water, whole pyrolysis process exhaust matter at last is pollution-free, the environmental protection, and resource utilization is high.
Further, the treatment method of the embodiment further includes the steps of performing primary rapid cooling on the steam generated by the evaporation tank and the second tail gas through a chiller, performing secondary cooling through a second condenser, and finally introducing the third tail gas discharged from the second condenser into a dust remover for dust removal and then discharging the third tail gas. After secondary combustion, the combustible substances are ensured to be fully combusted, particularly, the dioxin monomer is fully decomposed and is not synthesized any more after quenching, so that the final emission reaches the standard. The dust remover can remove the particle dust and fly ash impurity in the tail gas discharged finally, and prevent the environmental pollution. However, during secondary combustion, a large amount of gaseous water is generated by burning tar, alkane and alkene (containing hydrogen atoms) substances in a secondary combustion chamber, and after quenching, much water is still contained in the gas, and liquid water is separated out when the gas enters a dust remover to damage the dust remover, particularly, a pulse bag dust remover is often adopted in pyrolysis dust removal. At present, the working temperature of the bag-type dust remover is usually not more than 200 ℃ and not less than 130 ℃, because tail gas is easy to synthesize dioxin again at the temperature of 300-350 ℃, and the higher the working temperature is, the higher the requirement on the bag-type dust remover is; the reason why the working temperature is not lower than 130 ℃ is that under normal pressure, 100 ℃ is dew point temperature, and condensation is easily formed below 100 ℃ to cause 'bag pasting', and finally, a cloth bag is blocked.
In this embodiment, low-temperature pyrolysis is adopted, the temperature of pyrolysis gas in the pyrolysis furnace is about 80-180 ℃, therefore, the temperature of the first tail gas discharged by the pyrolysis furnace is about 80-180 ℃, after the first condenser is used for condensation, the gas temperature is reduced to below 80 ℃, and the temperature of the gas entering the secondary combustion chamber is about 60 ℃ due to the temperature loss of the gas in the pipeline circulation process. The temperature during secondary combustion is extremely high, the temperature of the gas in the secondary combustion chamber can reach 800-1100 ℃, the temperature of the second tail gas discharged from the secondary combustion chamber can reach 550-700 ℃, and the temperature is higher, so that the high temperature is utilized for evaporating the evaporation tank. After the second tail gas is quenched, the temperature can be reduced to about 120 ℃, although the temperature does not reach the dew point, because the combustion substance of the second combustion chamber contains a large amount of hydrogen elements, a large amount of water vapor is generated in the combustion, and supersaturated water vapor is easily formed to form mist water. The temperature of the gas exiting the second condenser was about 70 c.
Further, the pyrolysis furnace, the first condenser, the second combustion chamber, the quencher, the second condenser, the dust remover and the fan of the embodiment are sequentially connected through pipelines, and the tail gas is enabled to circulate in the device under the action of the fan. The evaporation pool is communicated with the first condenser through a pipeline, so that condensed water of the first condenser flows into the evaporation pool; the evaporation pool is connected with a pipeline for discharging second tail gas from the second combustion chamber through a pipeline, so that steam generated by the evaporation pool is converged with the second tail gas for treatment. Because the pipelines are communicated, under the action of the fan, power can be provided for the pipelines through which the condensed water flows into the evaporation pool and the steam flows to the second combustion chamber to discharge the second tail gas, and no additional power equipment is needed.
Example two
The difference between the present embodiment and the first embodiment is that, on the basis of the first embodiment, the present embodiment further describes the post-treatment of the tail gas.
As shown in fig. 2, in this embodiment, after condensing the first tail gas generated by pyrolysis in the pyrolysis furnace through the first condenser, the first tail gas is introduced into the second combustion chamber for secondary combustion, the second tail gas generated by secondary combustion is quenched and condensed for the second time to form a third tail gas, and finally, the third tail gas is introduced into the dust remover for dust removal and then discharged. In this embodiment, the third off-gas is transported between the second condenser and the dust remover through a pipeline, and the pipeline is heated from the outside.
In the first embodiment, after quenching and before dedusting, the gas is condensed for the second time, so that about 70% of moisture in the tail gas can be removed, but the moisture cannot be completely removed, because the tail gas flows in the second condenser, gaseous water which is not subjected to condensation and mist water which is not subjected to condensation are discharged from the second condenser along with the gas, and a small part of the gaseous water and the mist water still enter the deduster. This embodiment heats the connecting tube between second condenser and the dust remover, lets the gas temperature who flows to in the pipeline rise, can make the evaporation of fog form water in the tail gas of second condenser exhaust for gaseous water, avoids appearing in getting into the dust remover, can prevent "stick with paste the bag".
Specifically, in this embodiment, a pipeline for conveying the third tail gas between the second condenser and the dust remover passes through the heating chamber, the second tail gas generated by the secondary combustion is introduced into the heating chamber, the pipeline for conveying the third tail gas is heated by using the residual heat of the second tail gas, and then the second tail gas in the heating chamber is discharged to the quencher. The temperature of the second tail gas is high, the second tail gas is input into the heating chamber, the gas entering the dust remover can be heated by utilizing the heat exchange principle, so that the pipeline between the second condenser and the dust remover is heated without adding an extra heat source, resources are fully utilized, and the cost is reduced. And after the second tail gas exchanges heat with the gas to be introduced into the dust remover, the temperature of the second tail gas is reduced and then the second tail gas is introduced into the quencher, so that the load of the quencher can be reduced, and the quenching effect is more favorably realized.
This embodiment does not have newly-increased tail gas at whole in-process, also does not reduce tail gas, and the tail gas waste heat heating of the second combustion chamber of profit contains the tail gas of atomized water, when reaching resource rational utilization, has solved the "bag stick with paste" problem of rear end sack dust removal again.
In addition, the heating chamber of this embodiment passes through the pipeline and is connected with second combustion chamber and quencher, because the gas is the circulation, under the effect of fan, the second tail gas lets in the heating chamber after the second combustion chamber is discharged, discharges to the quencher again, need not to be equipped with other power equipment, reduce cost.
Other steps in this embodiment are the same as those in the first embodiment, and are not described herein again.
EXAMPLE III
As shown in fig. 3, a system for processing low-temperature pyrolysis tail gas according to a preferred embodiment of the present embodiment includes a pyrolysis furnace 1, a first condenser 2, two combustion chambers 3 and evaporation pond 4, pyrolysis oven 1 has the exhanst gas outlet, first condenser 2 has first air inlet, first gas outlet and comdenstion water export, two combustion chambers 3 have second air inlet and second gas outlet, evaporation pond 4 is confined cell body, evaporation pond 4 has water inlet and vapor outlet, the exhanst gas outlet passes through flue gas pipeline 5 and first air inlet intercommunication, first gas outlet passes through two combustion chambers inlet pipe 6 and second air inlet intercommunication, the second gas outlet is connected with two combustion chambers outlet pipe 7, the comdenstion water export passes through drainage pipe 8 and water inlet intercommunication, vapor outlet passes through vapor pipe 10 and two combustion chambers outlet pipe 7 intercommunication, two combustion chambers outlet pipe 7 is through evaporation pond 4 and carry out the heat transfer with evaporation pond 5. The first tail gas of pyrolysis oven 1 through flue gas pipeline 5 discharge is condensed in to first condenser 2, and gaseous second combustion chamber 3 that carries out is arranged into through second combustion chamber inlet pipe 6, reduces the water content that gets into the gaseous of second combustion chamber burning, helps going on smoothly and reducing the use amount of fuel of second combustion chamber burning. Condensed water obtained after condensation of the first tail gas is a mechanical mixture containing tar, inorganic compounds and the like, and then the condensed water is introduced into the evaporation tank 4 through the drainage pipeline 8 and is evaporated in the evaporation tank 4, wherein water is changed into steam and is separated from the tar in the condensed water, so that the tar is left in the evaporation tank 4, and the steam is converged into the outlet pipeline 7 of the secondary combustion chamber through the steam pipeline 10 and is treated together with the second tail gas discharged from the secondary combustion chamber 2. And, second combustion chamber outlet pipe 7 passes through evaporation pond 4, and what flows in second combustion chamber outlet pipe 7 is the second tail gas that second combustion chamber 3 post combustion discharged, and the temperature of second tail gas is higher, when passing through evaporation pond 4, because the heat transfer, can supply heat to the comdenstion water in the evaporation pond 4, realizes the make full use of resource.
Further, the system of the embodiment further comprises a quencher 11, a second condenser 12, a dust remover 13 and a fan 14, wherein the outlet pipeline 7 of the second combustion chamber, the quencher 11, the second condenser 12, the dust remover 13 and the fan 14 are communicated in sequence. Under the action of the fan 14, the tail gas can flow among the pyrolysis furnace 1, the first condenser 2, the second combustion chamber 3, the quencher 11, the second condenser 12 and the dust remover 13 in sequence, the evaporation pool 4 is communicated with the first condenser 2 through the water drainage pipeline 8 and is communicated with the second combustion chamber outlet pipeline 7 through the steam pipeline 10, and under the action of the fan 14, the air pressure at the steam pipeline 10 is low, so that condensed water can flow into the evaporation pool 4 from the water drainage pipeline 8, and steam in the evaporation pool 4 can flow into the second combustion chamber outlet pipeline 7 without being additionally provided with power equipment.
Example four
The difference between the present embodiment and the third embodiment is that, on the basis of the third embodiment, the present embodiment is provided with a delayed water inlet device on the water discharge pipeline 8.
Since the flow of the condensed water is powered by the fan 14, when the system is in operation, the fan 14 is turned on and the gas starts to circulate. However, it takes a period of time for the first tail gas to condense in the first condenser 2, if the drainage pipeline 8 is immediately conducted, when the condensed water is not formed, the first tail gas which is not condensed in the first condenser 2 is led to the evaporation tank 4, and then passes through the quencher 11, the second condenser 12, the dust remover 13 and the fan 14 without passing through the second combustion chamber 3, and the first tail gas contains pollutants such as dioxin, and if the first tail gas does not pass through the second combustion, the first tail gas is discharged to the atmosphere to cause pollution. Therefore, in this embodiment, a water inlet delay device is disposed on the water discharge pipeline 8, so that the water discharge pipeline 8 is communicated with the condensed water after the first condenser 2 is opened for a period of time.
Alternatively, as shown in fig. 4, the water inlet delay device may be a control valve 9, and the control valve 9 is installed on the water discharge pipeline 8 to control the opening and closing of the water discharge pipeline 8. After the first condenser 2 works for a period of time, a certain amount of condensed water is formed in the first condenser 2, and the control valve 9 is opened to allow the condensed water to flow into the evaporation tank 4, so that the tail gas which is not subjected to secondary combustion can be prevented from being discharged.
Other structures of this embodiment are the same as those of this embodiment, and are not described herein again.
EXAMPLE five
The difference between the present embodiment and the fourth embodiment is that the water inlet delay device of the present embodiment is different from the fourth embodiment.
As shown in fig. 5, the water inlet delay device of this embodiment includes a sinking elbow 15 and a water feeding pipe 16, the water discharging pipe 8 is divided into a first water discharging pipe section and a second water discharging pipe section, the first water discharging pipe section is connected to the condensed water outlet of the first condenser 2 and one end of the sinking elbow 15, and the second water discharging pipe section is connected to the other end of the sinking elbow 15 and the water inlet of the evaporation tank 4. The water feeding pipe 16 is connected with the first water discharging pipe section, and the water feeding pipe 16 is provided with a switch valve 17.
When the system is started for the first time, because no condensate exists in the sinking elbow 15 or the sinking elbow 15 is not filled with the condensate, under the negative pressure condition of the fan 14, the pressure condition in the system is as follows: the second combustion chamber outlet pipeline 7 > Tg, the steam pipeline 10 > Tg, the evaporation pool 4 > Tg, the water drainage pipeline 8 > Tg, the first condenser 2, and the first tail gas are directly pumped into the second combustion chamber outlet pipeline 7. Therefore, when the water-sealed type submerged elbow is used for the first time, the switch valve 17 is opened, the submerged elbow 15 is filled with water manually, the switch valve 17 is closed, water sealing is formed, the negative pressure of the fan 14 is not enough to completely extract the water from the submerged elbow 15, and therefore the water sealing state can play an isolation role for a long time in the starting and continuous working processes. When a certain amount of condensed water is formed in the first condenser 2, the condensed water flows into the first drainage pipe section and is gathered in the sinking elbow 15, and when the condensed water reaches the bottom height inside the second drainage pipe section, the condensed water enters the evaporation tank 4.
The submerged elbow 15 of this embodiment is a U-shaped structure, the height of the submerged elbow 15 is H, and the size of H has an associated relationship with the negative pressure of the fan 14. And if the working negative pressure value of the fan 14 is a meters of water column, H is a f, wherein f is a safety factor, and the value of f is 1.1-2. In this example, f is 1.2.
Other structures of this embodiment are the same as those of this embodiment, and are not described herein again.
EXAMPLE six
The present embodiment is different from the fifth embodiment in that, on the basis of the fifth embodiment, the second condenser 12 and the dust remover 13 of the present embodiment are communicated through a connecting pipe 18, and a heating device is covered outside the connecting pipe 18, as shown in fig. 6.
When the gas is combusted secondarily in the secondary combustion chamber 3, a large amount of gaseous water is generated by the combustion of tar, alkane and alkene (containing hydrogen atoms) in the secondary combustion chamber, after the gas is quenched by the quencher 11, the water in the gas is still more, when the gas enters the dust remover 13, liquid water is separated out, the dust remover 13 is damaged, and particularly, a pulse bag dust remover is usually adopted in the pyrolysis dust removal. The dust remover 13 of this embodiment adopts the pulse bag dust remover, and gaseous state water and fog water can lead to "sticking with paste the bag" in entering into dust remover 13, cause dust remover 13 to block up. Although the second condenser 12 is provided for condensation, the present embodiment cannot completely remove moisture in the gas, and still has the risk of "sticking to the bag". Therefore, in this embodiment, the connecting pipe 18 between the second condenser 12 and the dust remover 13 is heated to raise the temperature of the gas entering the dust remover 13, so that the mist water in the tail gas discharged from the second condenser 12 is evaporated into gaseous water, thereby avoiding the separation of the gaseous water in the dust remover 13 and preventing the "bag sticking".
Other structures of this embodiment are the same as those of the fifth embodiment, and are not described herein again.
EXAMPLE seven
The present embodiment is different from the sixth embodiment in that the present embodiment further describes a heating apparatus on the basis of the sixth embodiment.
As shown in fig. 7, the heating apparatus of the present embodiment includes a heating chamber 19, an air inlet pipe 20 and an air return pipe 21, the heating chamber 19 is a box body, openings are provided on two opposite sides of the heating chamber 19, the connecting pipe 18 passes through the heating chamber 19 through the openings, the heating chamber 19 has an inlet and an outlet, the outlet pipe 7 of the second combustion chamber is communicated with the inlet through the air inlet pipe 20, and the outlet is communicated with the quencher 11 through the air return pipe 21. The temperature of the second tail gas discharged to the outlet pipeline 7 of the second combustion chamber after the gas is combusted in the second combustion chamber 2 is higher, the second tail gas is introduced into the heating chamber 19 through the gas inlet pipe 20 and can exchange heat with the connecting pipeline 18 penetrating through the heating chamber 19, so that the temperature of the gas in the connecting pipeline 18 is increased, and the phenomenon that the gas in the connecting pipeline 18 is too low and dew condensation is caused after the gas enters the dust remover 13 to cause bag pasting is avoided. The second tail gas is fully utilized, a heat source is not required to be additionally increased, and the cost is reduced.
Other structures of this embodiment are the same as those of the sixth embodiment, and are not described herein again.
Example eight
The difference between the present embodiment and the seventh embodiment is that, on the basis of the seventh embodiment, the present embodiment is provided with the adjusting valve 22 for adjusting the flow rate of the return air pipe 21, so as to adjust the flow rate of the return air pipe 21 and indirectly control the final temperature of the gas in the connecting pipeline 18, as shown in fig. 8.
The other structures of this embodiment are the same as those of the seventh embodiment, and are not described herein again.
Example nine
The difference between this embodiment and the eighth embodiment is that, as shown in fig. 9, the second combustion chamber outlet pipeline 7 of this embodiment is connected to the quencher 11, the gas inlet pipe 10 and the gas return pipe 21 are both connected to the second combustion chamber outlet pipeline 7, the connection between the gas inlet pipe 10 and the second combustion chamber outlet pipeline 7 is closer to the second combustion chamber 3, and the connection between the gas return pipe 21 and the second combustion chamber outlet pipeline 7 is closer to the quencher 11. Since the quencher 11 is closer to the fan 14 than the second chamber 3, the pressure in the region closer to the quencher 11 is lower, and therefore, the pressure in the gas return pipe 21 is lower than that in the gas inlet pipe 10, a part of the second exhaust gas enters the heating chamber 19 through the gas inlet pipe 10 and then flows back through the gas return pipe 21, and another part of the second exhaust gas enters the quencher 11 directly for quenching. It is avoided that all the second tail gas enters the heating chamber 19, which results in the gas temperature at the connecting pipe 18 being too high, and the pyrolysis gas in the pyrolysis furnace 1 is discharged too slowly, which results in the gas pressure being high.
Further, the outlet pipeline 1 of the second combustion chamber of the present embodiment is connected with the quencher 11 and the gas inlet pipe 10 through a three-way pipe, the outlet pipeline 1 of the second combustion chamber, the quencher 11 and the gas inlet pipe 10 are respectively connected to three ways of the three-way pipe, and the gas return pipe 21 is connected to one way of the three-way pipe connected with the quencher 11.
Other structures of this embodiment are the same as those of the eighth embodiment, and are not described herein again.
Example ten
The difference between this embodiment and the ninth embodiment is that the second combustion chamber outlet pipeline 7, the gas inlet pipe 10, the gas return pipe 21 and the quencher 11 are connected differently as shown in fig. 10.
In this embodiment, the system further includes a gas distributor 23, a gas inlet elbow 24 and a gas return elbow 25, the gas distributor 23 is a box, two opposite sides of the gas distributor 21 are respectively provided with a first connection port and a second connection port, the second combustion chamber outlet pipeline 7 is connected with the first connection port, and the quencher 11 is connected with the second connection port through a pipeline. The top side of gas distributor 21 is equipped with third connector and fourth connector, and the third connector is close to first connector setting, the fourth connector is close to the second connector setting, go into gas elbow 24 and return-air elbow 25 and locate in gas distributor 23, go into a port and the third connector connection of gas elbow 24, another port of going into gas elbow 24 is towards first connector, a port and the fourth connector connection of return-air elbow 25, another port of return-air elbow 25 is towards the second connector, go into trachea 20 and third connector connection, return-air pipe 21 and fourth connector connection. When the second tail gas in the outlet pipeline 7 of the second combustion chamber enters the gas distributor 23 through the first connecting port, one part of the second tail gas enters the gas inlet pipe 20 through the gas inlet elbow 24, and the other part of the second tail gas directly enters the gas distributor 23 through the gas distributor 23.
Other structures of this embodiment are the same as those of the eighth embodiment, and are not described herein again.
In summary, the embodiment of the present invention provides a method for treating low-temperature pyrolysis tail gas, in which a first tail gas generated by pyrolysis in a pyrolysis furnace is condensed by a first condenser, and then introduced into a second combustion chamber for secondary combustion; the condensed water generated during condensation of the first tail gas is introduced into the evaporation tank, the condensed water in the evaporation tank is evaporated by using the waste heat of the second tail gas generated by secondary combustion, the steam generated in the evaporation tank and the second tail gas are treated together, water and tar in the condensed water can be separated, and the tar left in the evaporation tank can be put into the pyrolysis furnace for decomposition and utilization again after being solidified, so that zero emission is achieved, other treatments of other hazardous waste water are not required, the cost is reduced, and the evaporation tank supplies heat by the high-temperature second tail gas discharged by the secondary combustion, and a heat source is not required to be additionally provided; and then, the steam generated by the evaporation tank and the second tail gas are rapidly cooled primarily by a quencher, are cooled secondarily by a second condenser, and finally the third tail gas discharged from the second condenser is discharged after being introduced into a dust remover for dust removal. The pipeline for conveying the third tail gas between the second condenser and the dust remover is heated by utilizing the waste heat of the second tail gas, so that the temperature of the gas discharged by the second condenser can be increased, the mist water in the gas is evaporated into gaseous water, and the gas is prevented from dewing after entering the dust remover to cause bag pasting.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for treating tail gas generated by low-temperature pyrolysis is characterized in that first tail gas generated by pyrolysis in a pyrolysis furnace is condensed by a first condenser and then is introduced into a secondary combustion chamber for secondary combustion; and the condensed water generated during condensation of the first tail gas is introduced into the evaporation tank, the condensed water in the evaporation tank is evaporated by using the waste heat of the second tail gas generated by secondary combustion, and the steam generated in the evaporation tank and the second tail gas are treated together.
2. The method for treating the low-temperature pyrolysis tail gas according to claim 1, wherein the steam generated by the evaporation tank and the second tail gas are subjected to primary rapid cooling through a chiller, then subjected to secondary cooling through a second condenser, and finally discharged after the third tail gas discharged from the second condenser is introduced into a dust remover for dust removal.
3. The method for treating the low-temperature pyrolysis tail gas according to claim 2, wherein the third tail gas is conveyed between the second condenser and the dust remover through a pipeline, and the pipeline is heated from the outside.
4. The method for treating the low-temperature pyrolysis tail gas according to claim 3, wherein a pipeline for conveying the third tail gas between the second condenser and the dust remover passes through the heating chamber, the second tail gas generated by the secondary combustion is introduced into the heating chamber, the pipeline for conveying the third tail gas is heated by using the waste heat of the second tail gas, and then the second tail gas in the heating chamber is discharged to the quencher.
5. The system for treating the low-temperature pyrolysis tail gas is characterized by comprising a pyrolysis furnace (1), a first condenser (2), a second combustion chamber (3) and an evaporation tank (4), wherein the pyrolysis furnace (1) is provided with a flue gas outlet, the first condenser (2) is provided with a first air inlet, a first air outlet and a condensate outlet, the second combustion chamber (3) is provided with a second air inlet and a second air outlet, the evaporation tank (4) is a closed tank body, the evaporation tank (4) is provided with a water inlet and a steam outlet, the flue gas outlet is communicated with the first air inlet through a flue gas pipeline (5), the first air outlet is communicated with the second air inlet through a second combustion chamber inlet pipeline (6), the second air outlet is connected with a second combustion chamber outlet pipeline (7), and the condensate outlet is communicated with the water inlet through a drainage pipeline (8), the steam outlet is communicated with the second combustion chamber outlet pipeline (7) through a steam pipeline (10), and the second combustion chamber outlet pipeline (7) passes through the evaporation pool (4) and exchanges heat with the evaporation pool (4).
6. The system for treating the low-temperature pyrolysis tail gas according to claim 5, further comprising a quencher (11), a second condenser (12), a dust remover (13) and a fan (14), wherein the second combustion chamber outlet pipeline (7), the quencher (11), the second condenser (12), the dust remover (13) and the fan (14) are communicated in sequence.
7. The system for treating the low-temperature pyrolysis tail gas as recited in claim 6, wherein a water inlet delaying device is arranged on the water discharge pipeline (8).
8. The system for treating the low-temperature pyrolysis tail gas according to claim 6, wherein the second condenser (12) is communicated with the dust remover (13) through a connecting pipeline (18), and a heating device is coated outside the connecting pipeline (18).
9. The system for processing the tail gas of the low-temperature pyrolysis according to claim 8, wherein the heating device comprises a heating chamber (19), an air inlet pipe (20) and an air return pipe (21), the heating chamber (19) is a box body, two opposite sides of the heating chamber (19) are provided with openings, the connecting pipeline (18) penetrates through the heating chamber (19) through the openings, the heating chamber (19) is provided with an inlet and an outlet, the outlet pipeline (7) of the secondary combustion chamber is communicated with the inlet through the air inlet pipe (20), and the outlet is communicated with the quencher (11) through the air return pipe (21).
10. The system for treating the tail gas generated by the low-temperature pyrolysis according to claim 1, wherein the air return pipe (21) is provided with a regulating valve (22) for regulating the flow rate of the air return pipe.
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