CN216297501U - Molten salt circulating type in-situ thermal desorption soil remediation system - Google Patents
Molten salt circulating type in-situ thermal desorption soil remediation system Download PDFInfo
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Abstract
The utility model discloses a molten salt circulating type in-situ thermal desorption soil remediation system, and belongs to the technical field of soil remediation. The system comprises a molten salt tank, a molten salt furnace and a heater, wherein the molten salt tank is connected with the molten salt furnace through a molten salt pump, the output end of the molten salt furnace is connected with the heater embedded in the polluted soil, the output end of the heater is connected with the molten salt tank, an extraction pipe is arranged around the heater, and the extraction pipe is also embedded in the polluted soil; the extraction pipe is connected with the waste gas treatment device through a waste gas pipeline. The indirect thermal desorption heat transfer efficiency of the utility model is greatly improved, the molten salt can be recycled, the thermal desorption temperature requirement of the organic matters difficult to volatilize can be met, and the application range is wider.
Description
Technical Field
The utility model belongs to the technical field of contaminated site soil remediation, is suitable for remediation of organic contaminated site soil, and particularly relates to a molten salt circulating type in-situ thermal desorption soil remediation system.
Background
The soil is a loose surface layer which has fertility and can grow plants on the surface of the land, when harmful substances discharged into the soil exceed the self-cleaning capacity of the soil, the composition, the structure and the function of the soil are changed, the activity of microorganisms is inhibited, the harmful substances or decomposition products thereof are gradually accumulated in the soil and absorbed by the human body through the soil → the plants → the human body or through the soil → water → the human body indirectly, and the soil pollution is generated to the extent of harming the health of the human body.
The current seriously polluted sites mainly comprise chemical plants, pesticide plants, smelting plants, gas stations, chemical storage tanks and the like, the pollutants of the sites mainly comprise organic pollution, and the sites can be divided into volatile organic compounds, semi-volatile organic compounds, persistent organic compounds, pesticides and the like according to the difference of the melting boiling points of the volatile organic compounds, the semi-volatile organic compounds, the persistent organic compounds and the like. The polluted soil restoration technology comprises incineration (cement kiln cooperative treatment), phytoremediation, bioremediation, chemical remediation, thermal desorption and the like, wherein the thermal desorption technology has the advantages of high treatment efficiency, short restoration period, movable device and the like, is widely applied to restoration of volatile/semi-volatile organic polluted sites, and is one of the main site restoration technologies, wherein the thermal desorption accounts for 20-30% in European and American site restoration cases, as shown by American EPA statistics.
The thermal desorption technology is that the excavated polluted soil is heated to a boiling point of a target pollutant through direct or indirect heating, and the pollutant is gasified and volatilized selectively by controlling the system temperature and the material retention time, so that the target pollutant is separated and removed from soil particles. The thermal desorption technology is divided into direct thermal desorption and indirect thermal desorption according to a heat transfer mode, and is divided into in-situ thermal desorption and ex-situ thermal desorption according to an implementation mode, wherein the in-situ indirect thermal desorption has the advantages of wide practicability, small tail gas treatment capacity and the like, can be implemented in a place with a building, and is wide in application.
According to the 'polluted soil restoration engineering technical specification in-situ thermal desorption' HJ1165-2021 issued by the ministry of ecological environment, the existing in-situ indirect thermal desorption is divided into 4 forms of gas heat conduction heating, electric heat conduction heating, electrode heating and steam injection heating according to the heating mode. Meanwhile, because the inside and the outside of the heating well are respectively provided with the flue gas and the soil, the gas-solid heat transfer efficiency is very low, the discharged flue gas still carries a large amount of heat, the energy utilization rate is low, and the energy consumption is high; the electric heating conduction heating is to heat soil by using a resistance rod, 1-degree electric energy can only generate 1kw of heat, 1-degree fuel gas or 1 liter of fuel oil can generate 10-12 kw of heat, and the industrial electricity price and the fuel gas and fuel oil prices are combined, so that the cost of the electric heating conduction heating is relatively high and uneconomical, and one ton of soil is usually required to complete the thermal desorption reaction by about 300kw of heat, once multiple heating points are implemented in a large scale, large-scale power supply facilities are required for assistance, so the use scale is limited; the electrode heating utilizes the discharge between the electrodes, and the electricity is conducted and heated through the soil, so that the problems of high cost, uneconomic performance, limited scale and the like exist, and the safety risk of current leakage also exists; steam injection heating is preferentially selected when a steam source meeting project requirements exists around a land, a steam boiler is generally adopted for field self-production, the steam temperature is generally below 200 ℃, the thermal desorption temperature of organic pollutants such as semi-volatile organic compounds and polycyclic aromatic hydrocarbons is generally required to be 350-550 ℃, so the steam injection heating can only be suitable for the thermal desorption of volatile organic compounds and cannot meet the thermal desorption temperature requirement of the volatile organic compounds, fresh water resources are additionally consumed for producing steam, condensed water can be formed after the steam is cooled, heat needs to be absorbed again in the gradual temperature rise process of soil, and waste of water resources and energy is caused.
SUMMERY OF THE UTILITY MODEL
The utility model provides a molten salt circulating type in-situ thermal desorption soil remediation system and method aiming at the defects in the prior art.
The purpose of the utility model can be realized by the following technical scheme:
a molten salt circulating type in-situ thermal desorption soil remediation system comprises a molten salt tank, a molten salt furnace and a heater, wherein the molten salt tank is connected with the molten salt furnace through a molten salt pump, the output end of the molten salt furnace is connected with the heater embedded in polluted soil, the output end of the heater is connected with the molten salt tank, a suction pipe is arranged around the heater, and the suction pipe is also embedded in the polluted soil; the extraction pipe is connected with the waste gas treatment device through a waste gas pipeline.
In the above system: the heater comprises an inner tube and an outer tube, the inner tube is sleeved in the outer tube to form a jacket, the top and the bottom of the inner tube are open, the bottom of the outer tube is closed, and the top of the outer tube is provided with an output end.
In the above system: the heaters are arranged in the polluted soil at intervals of 1.5-3.5 m in a honeycomb shape at multiple points at intervals, and are converged to a header pipe through a heating pipeline and a return pipeline, and finally correspond to the molten salt furnace.
A method for realizing fused salt circulating in-situ thermal desorption soil remediation by using the system comprises the following steps:
the first step is as follows: the method comprises the following steps that molten salt with the temperature of 400-600 ℃ in a molten salt tank is driven by a molten salt pump, and is heated by smoke generated by fuel combustion in a molten salt furnace of a circulation loop to absorb heat, the temperature is raised to 700-800 ℃, and then the polluted soil is heated by a heater to release heat;
the second step is that: the molten salt in the heater is cooled to about 400-600 ℃, and finally returns to the molten salt tank through a return pipeline, so that heat is continuously absorbed and released while the molten salt circularly flows, and the molten salt is an energy transmission medium to indirectly transfer heat generated by fuel combustion to the polluted soil; the polluted soil is heated and then undergoes thermal desorption reaction, and the generated thermal desorption waste gas is pumped out through the extraction pipe, passes through the waste gas pipeline and finally is purified and disposed in the waste gas treatment device.
The method comprises the following steps: the molten salt medium enters from the top of the inner pipe, flows into the jacket from the bottom and finally flows out from the upper part of the outer pipe.
The method comprises the following steps: when the heating salt circulation is stopped, the residual molten salt in the circulation loop is blown back to the molten salt tank by introducing compressed gas, so that the phenomenon that the pipeline is blocked by the solidified molten salt after the temperature is reduced is avoided.
The method comprises the following steps: the molten salt contains NaCl and BaCl2And CaCl2(ii) a Further preferably: NaCl, BaCl2And CaCl2The mass ratio of (A) to (B) is 10-30: 20-40: 40-60.
The utility model has the beneficial effects that:
(1) the indirect thermal desorption heat transfer efficiency is greatly improved: since the efficiency of indirect heating of conventional flue gas by stainless steel cylinders is limited by the heat transfer properties of the flue gas and the stainless steel cylinders (the heat transfer coefficient is typically only 20-30W/m2. degree. c.). And the heat transfer efficiency of the liquid molten salt and the stainless steel cylinder is high (estimated to be more than 200W/m2℃). Compared with the gas heat conduction heating heat transfer performance, the heat transfer efficiency is greatly improved.
(2) The molten salt is recycled, namely residual heat carried by the molten salt after heat release is not wasted, so that the energy utilization rate is high, energy is saved compared with gas heat conduction heating, and the energy consumption is low.
(3) The molten salt furnace can adopt various modes such as gas and fuel oil, is more flexible and convenient, does not need high-power supply equipment and boiler equipment for assistance, does not need to consume extra fresh water resources, is easier to be applied in a large scale and has lower use cost compared with electric heat conduction heating, electrode heating and steam injection heating.
(4) The working temperature of the molten salt is as high as above 700 ℃, the requirement of the thermal desorption temperature of the organic matters difficult to volatilize can be met, and the application range is wider.
Drawings
FIG. 1 is a flow chart of a molten salt circulating in-situ thermal desorption soil remediation system.
Wherein: 1 is fused salt groove, 2 fused salt, 3 is the fused salt pump, 4 is the fused salt stove, 5 is the heating pipeline, 6 is the heater, 7 is the return line, 8 is the extraction pipe, 9 exhaust gas pipeline, 10 is the exhaust treatment device, 11 is the compressed gas.
Fig. 2 is a schematic diagram of a heater configuration.
Wherein: 6-1 is an inner tube, and 6-2 is an outer tube.
Detailed Description
The utility model is further illustrated by the following examples, without limiting the scope of the utility model: example 1:
referring to fig. 1-2, a molten salt circulating in-situ thermal desorption soil remediation system comprises a molten salt tank 1, a molten salt furnace 4 and a heater 6, wherein the molten salt tank 1 is connected with the molten salt furnace 4 through a molten salt pump 3, the output end of the molten salt furnace 4 is connected with the heater 6 embedded in polluted soil, the output end of the heater 6 is connected with the molten salt tank 1, 872 extraction pipes 8 are distributed around the heater 6 in a honeycomb shape and are also embedded in the polluted soil; the extraction pipe 8 is connected to an exhaust gas treatment device 10 via an exhaust gas line 9.
The heater 6 comprises an inner tube 6-1 and an outer tube 6-2, the inner tube 6-1 is sleeved in the outer tube 6-2 to form a jacket, the top and the bottom of the inner tube 6-1 are open, the bottom of the outer tube 6-2 is closed, and an output end is arranged at the top.
190 groups of heaters 6 are arranged in the polluted soil at intervals of 2.6m in a honeycomb shape at multiple points, and are collected to a header pipe through a plurality of branch pipes in a heating pipeline 5 and a return pipeline 7, and finally correspond to the same set of molten salt furnace 4.
190 groups of heaters 6 and 872 extraction pipes 8 form an in-situ thermal desorption area with the length and width of 50m and the total length of 2500 square meters.
The area only needs to be provided with 1 molten salt tank 1 and 1 molten salt furnace 4 respectively, namely 1 burner and a control valve group thereof.
By adopting the scheme, the working process and parameters are as follows:
the first step is as follows: the molten salt 2 with the temperature of 500-520 ℃ in the molten salt tank 2 is driven by a molten salt pump 3, is heated by smoke generated by fuel combustion in a molten salt furnace 4 of a circulation loop, absorbs heat, is heated to 700-720 ℃, and then is heated to pollute soil by a heater 6 to release heat;
the second step is that: the molten salt in the heater is cooled to 500-520 ℃, and finally returns to the molten salt tank 1 through the return pipeline 7, so that heat is continuously absorbed and released while the molten salt circularly flows, and the molten salt is an energy transmission medium to indirectly transfer heat generated by fuel combustion to the polluted soil; the polluted soil is heated and then undergoes thermal desorption reaction, and the generated thermal desorption waste gas is pumped out through the pumping-out pipe 8, passes through the waste gas pipeline 9 and finally is purified in the waste gas treatment device 10.
The molten salt medium enters from the top of the inner pipe 6-1, flows into the jacket from the bottom and finally flows out from the upper part of the outer pipe 6-2.
When the heating salt circulation is stopped during melting, the residual molten salt in the circulation loop is blown back to the molten salt tank 1 by introducing compressed gas, so that the phenomenon that the pipeline is blocked by the solidified molten salt after temperature reduction is avoided.
The molten salt 2 contains NaCl and BaCl as components2And CaCl2The mass ratio of (A) to (B) is 20: 30: 50.
the power consumption of the whole device is about 250 kilowatts, and the consumption of natural gas is 300 cubic meters per hour.
Comparative example 1:
a flue gas heating type in-situ thermal desorption soil remediation system comprises a fuel gas supply device, an air supply device, a heater, a flue gas fan, an extraction pipe and a waste gas treatment device. The number of the heaters and the extraction pipes is the same as that of the embodiment, the heaters and the extraction pipes are distributed into 190 groups and 872 groups, and the distribution mode is also the same. The exhaust gas treatment device is the same as the embodiment.
Each heater was fitted with 1 small burner for a total of 190 burners. Each burner needs to be provided with a gas pressure reducing valve, a filter, a flame detector and other control valve groups, and the total number is 190.
The gas supply device and the air supply device need to distribute 190 groups of branch pipes to each burner, and each group of branch pipes need to be provided with an air regulating valve group, and the total number is 190 groups.
The flue gas generated by 190 burners is all led to a flue gas fan through a collecting pipe, and each branch pipe needs to be provided with a flue gas flow regulating valve, and the total number is 190 groups.
190 groups of heaters 6 and 872 extraction pipes 8 form an in-situ thermal desorption area with the length and width of 50m and the total length of 2500 square meters.
The power consumption of the whole device is about 500 kilowatts, and the consumption of natural gas per hour is 400 cubic meters.
By adopting the scheme, the working process and parameters are as follows:
the burner of each heater burns to generate high-temperature smoke at 700 ℃, part of heat is transferred to surrounding soil after passing through the heater, and meanwhile, the smoke is cooled to 400 ℃ and carries the heat to be discharged to the atmosphere.
Comparative example 2:
an electric heating type in-situ thermal desorption soil remediation system comprises a gas power supply device, an electric leakage protection device, a heater, an extraction pipe and a waste gas treatment device. The number of the heaters and the extraction pipes is the same as that of the embodiment, the heaters and the extraction pipes are distributed into 190 groups and 872 groups, and the distribution mode is also the same. The exhaust gas treatment device is the same as the embodiment.
190 groups of heaters (6) and 872 extraction pipes (8) form an in-situ thermal desorption area with the length and width of 50m and the total length of 2500 square meters.
The electric power of each group of heaters is 12 kilowatts, and the total amount is 2280 kilowatts.
190 groups of heaters share 1 power supply device.
Each group of heaters needs to be provided with 1 leakage protection device, and the total number of the heaters is 190.
By adopting the scheme, the working process and parameters are as follows:
each heater consumes 15 kilowatt hours of electric energy per hour to form a heating rod at 350 ℃ to heat surrounding soil.
Comparative example 3:
the utility model provides a steam injection formula normal position thermal desorption soil repair system, this system includes gas steam generating device, heater, extraction pipe, exhaust treatment device. The number of the heaters and the extraction pipes is the same as that of the embodiment, the heaters and the extraction pipes are distributed into 190 groups and 872 groups, and the distribution mode is also the same. The exhaust gas treatment device is the same as the embodiment.
190 groups of heaters (6) and 872 extraction pipes (8) form an in-situ thermal desorption area with the length and width of 50m and the total length of 2500 square meters.
The steam generating device comprises 1 steam boiler, 1 hot blast stove and 1 set of soft water supply device.
The power consumption of the whole device is about 250 kilowatts, and the consumption of natural gas per hour is 400 cubic meters.
By adopting the scheme, the working process and parameters are as follows:
the steam boiler generates 180 ℃ steam, and the surrounding soil is heated by the heater.
Claims (3)
1. The utility model provides a circulating normal position thermal desorption soil repair system of fused salt which characterized in that: the system comprises a molten salt tank (1), a molten salt furnace (4) and a heater (6), wherein the molten salt tank (1) is connected with the molten salt furnace (4) through a molten salt pump (3), the output end of the molten salt furnace (4) is connected with the heater (6) embedded in the polluted soil, the output end of the heater (6) is connected with the molten salt tank (1), an extraction pipe (8) is arranged around the heater (6), and the extraction pipe (8) is also embedded in the polluted soil; the extraction pipe (8) is connected with an exhaust gas treatment device (10) through an exhaust gas pipeline (9).
2. The system of claim 1, wherein: the heater (6) comprises an inner tube (6-1) and an outer tube (6-2), the inner tube (6-1) is sleeved in the outer tube (6-2) to form a jacket, the top and the bottom of the inner tube (6-1) are open, the bottom of the outer tube (6-2) is closed, and an output end is arranged at the top.
3. The system of claim 1, wherein: the heaters (6) are arranged in the polluted soil at intervals of 1.5-3.5 m in a honeycomb-shaped multi-point mode at intervals, are collected to a header pipe through the heating pipelines (5) and the return pipelines (7), and finally correspond to the molten salt furnace (4).
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| CN114101307A (en) * | 2021-11-10 | 2022-03-01 | 南京中船绿洲环保有限公司 | Fused salt circulating in-situ thermal desorption soil remediation system and method |
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| CN114101307A (en) * | 2021-11-10 | 2022-03-01 | 南京中船绿洲环保有限公司 | Fused salt circulating in-situ thermal desorption soil remediation system and method |
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