A Venturi-based soil thermal desorption and heat fluid and collection gas processing device and processing method

Abstract

A soil thermal desorption and addition hot fluid and collected gas processing device and processing method based on Venturi, comprising a heater, a circulation pump, a heating system, a circulation pipe, a pressure monitoring control valve, a temperature sensor, and a flow sensor, wherein the heating system comprises a Venturi tube and a heating tube, and the connection relationship of the heating system is configured as follows: the output end of the nth heating tube is connected to the input end of the n+1th Venturi tube; the advantages of the present invention are: the heating fluid flows through the Venturi collector to generate negative pressure, effectively collects desorbed gas, and reduces costs. The method collects desorbed gas, greatly simplifies the scale of repair equipment, is compact, and is economical to use; the collected organic waste gas is collected by the Venturi tube and then enters the circulation pipe, where it undergoes a physical and chemical reaction with the organic hot fluid after contacting it and enters the fluid, thereby achieving partial absorption, and the hot fluid enriched with gas is continuously circulated in the thermal desorption equipment, without generating waste gas overflow or secondary pollution.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection and soil remediation, and in particular to a Venturi-based soil thermal desiccation and heat-addition fluid and collection gas processing device and processing method. Background Art

[0002] At present, the treatment of organic contaminated soil in China mainly includes thermal desorption, leaching, air injection, chemical oxidation / reduction, two-way extraction, microorganisms and plants. Foreign countries have a more comprehensive understanding of the treatment mechanism and influencing factors of the thermal desorption process. They often simulate the thermal desorption process of organic pollutants in the soil by establishing a bed model to achieve the establishment and selection of parameters in engineering applications. The research on thermal desorption remediation of soil in my country started late, but there are a small number of cases. The on-site process is mainly to heat thermal desorption in an ex-situ rotary kiln followed by tail gas treatment. After treatment, the concentration of contaminated soil can basically reach the remediation target. In-situ thermal desorption mainly achieves the desorption of pollutants by increasing the temperature of the contaminated area. It can simultaneously treat soil and groundwater and has less impact on the surrounding environment. At present, there are more than ten pilot and remediation projects in my country. According to the heating method, in-situ thermal desorption can also be subdivided into steam heating, thermal conduction heating and resistance heating. At present, resistance heating is more commonly used.

[0003] The Chinese invention patent (CN102671932B) is an in-situ remediation system and method for deep mixing and hot air injection of contaminated soil. The lower end of the hot air injection pipe of the system is connected to the drill bit core tube in the drill bit, which effectively combines the heating device with the thermal desorption well. It can solve the "tailing effect" commonly found in the late stage of SVE remediation and improve the remediation efficiency. The patent makes technical improvements to the in-situ thermal desorption system of soil, but it cannot solve the problem of secondary pollution, and the system energy consumption is also high.

[0004] China's invention patent (CN201610065614), a circulating fluid thermal desorption soil pollution treatment method and device, is an improvement on the heat conduction desorption device in the in-situ thermal desorption of soil. The circulation pump can pump the heated high-boiling point liquid to the circulation pipeline, and the hot liquid flows through the site that needs to be heated, heating the soil contaminated site by heat conduction. However, the device only flows through the contaminated site once and then circulates. The polluted gas is still collected by the traditional gas collection well. The heating fluid is a heat-conducting medium such as clean heat carrier oil. It is a more traditional disposal method and cannot solve the problems of secondary pollution, resource recycling and system energy consumption. Summary of the invention

[0005] The object of the present invention is to provide a soil thermal desorption additional heat fluid and collection gas processing device and processing method based on Venturi.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A soil thermal degassing device based on Venturi for adding heat fluid and collecting gas, characterized in that it includes a heater and several heating systems, a temperature sensor is provided in the heater, the heating systems are connected in sequence, the outlet of the heater is connected to the front end of an outlet pipe, a circulating pump is provided at the front end of the outlet pipe, the rear end of the outlet pipe is connected to the input end of the frontmost heating system, the output end of the rearmost heating system is connected to the front end of the circulating pipe, a pressure monitoring control valve is provided at the front end of the circulating pipe, the pressure monitoring control valve is connected to a gas emergency treatment combustion device, a flow sensor is provided at the rear end of the circulating pipe, and the rear end of the circulating pipe is connected to the inlet of the heater,

[0008] Among them, each of the heating systems includes a venturi tube and a heating tube, the venturi tube and the heating tube are connected in sequence front to back, the venturi tube is connected to the gas collection pipe, the front and rear ends of the heating tube are straight tubes, the middle part of the heating tube is a U-shaped tube, and the two straight tubes are respectively connected to the front and rear ends of the U-shaped tube, and the connection relationship of the heating system is configured as follows: the output end of the nth heating tube is connected to the input end of the n+1th venturi tube.

[0009] Furthermore, the heater contains fuel oil.

[0010] Furthermore, the temperature of the fuel oil is 200-400°C.

[0011] Furthermore, the gas collecting pipe is provided with a first safety valve, and a second safety valve is provided between the pressure monitoring control valve and the gas emergency treatment combustion device.

[0012] Furthermore, a connection port is provided on the top of the heater.

[0013] A method for treating soil thermal desorption with added hot fluid and collected gas based on Venturi, characterized in that it comprises the following steps:

[0014] Step 1: Place the gas collection well and circulation pipeline at the appropriate location of the contaminated soil. Based on the specific pollutants, select and inject the heating fluid, such as fuel oil, check that the connections at each interface are tight, set the pressure monitoring control value, open the pressure monitoring control valve, close the second safety valve, and start the heater;

[0015] Step 2: When the temperature monitor shows that the heating fluid in the heater reaches the preset temperature, which is selected based on the specific pollutant and is generally 200-400°C, start the circulation pump;

[0016] Step 3: The hot fluid generates negative pressure through the Venturi tube. After the organic matter in the soil is heat-treated by the heating tube, the desorbed gas enters the circulation tube through the gas collection well and the Venturi tube under the action of negative pressure suction. In the process of flowing with the hot fluid, part of the gas dissolves in the hot fluid;

[0017] Step 4: As the system runs, the pressure monitoring control valve reaches a predetermined pressure, at which time the second safety valve is opened and the excess gas is led to the gas emergency treatment combustion device;

[0018] Step 5: After the repair is completed, turn off the heater, close the first safety valve, open the connection port on the top of the heater and the pressure monitoring control valve, collect the fuel in the heater and the remaining gas in the pipeline, and after the materials in the pipeline are collected, turn off the circulation pump.

[0019] The advantages of the present invention are: using the heated fluid to flow through the Venturi collector to generate negative pressure, the desorbed gas can be effectively collected, and the cost can be reduced. The desorbed gas collected by this method can replace the traditional in-situ thermal desorption extraction system to a certain extent, greatly simplify the scale of repair equipment, reduce the investment in gas transmission pipeline construction, and have a small size and economical use;

[0020] The collected organic waste gas is collected by the Venturi tube and then enters the circulation pipe. After contacting with the organic thermal fluid, a physical and chemical reaction occurs and the gas enters the fluid, which can achieve partial absorption. The thermal fluid enriched with gas continuously circulates in the thermal desorption equipment without generating waste gas overflow or secondary pollution. At the same time, some heat carrier oil enriched with non-explosive gases with higher calorific value can be appropriately introduced into the heater as auxiliary heating fuel, which effectively utilizes the calorific value of the waste gas and realizes the harmlessness of organic pollutants through combustion. For gases that cannot be directly absorbed, the thermal fluid can be decompressed and extracted after the repair project to collect the remaining waste gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure when the present invention is implemented specifically.

[0023] Reference numerals:

[0024] 1 heater 2 outlet pipe 3 heating system 4 venturi tube 5 heating pipe 6 circulation pipe

[0025] 7 Pressure monitoring control valve 8 Gas emergency treatment combustion device 9 Temperature sensor 10 Flow sensor

[0026] 11 Gas collection pipe 12 First safety valve 13 Second safety valve 14 Circulation pump 15 Connection port

[0027] 16 Exhaust gas emergency transportation and absorption device 17 Heating fluid emergency disposal device 18 Accident collection pool. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention discloses a soil thermal desorption device based on Venturi with added heat fluid and collected gas processing, such as Figure 1 As shown, it is characterized in that it includes a heater 1 and several heating systems 3, the heater 1 is provided with a temperature sensor 9, the heating systems 3 are connected in sequence, the outlet of the heater 1 is connected to the front end of the outlet pipe 2, the front part of the outlet pipe 2 is provided with a circulation pump 14, the rear end of the outlet pipe 2 is connected to the input end of the frontmost heating system 3, the output end of the rearmost heating system 3 is connected to the front end of the circulation pipe 6, the front end of the circulation pipe 6 is provided with a pressure monitoring control valve 7, the pressure monitoring control valve 7 is connected to the gas emergency treatment combustion device 8, the rear part of the circulation pipe 6 is provided with a flow sensor 10, the rear end of the circulation pipe 6 is connected to the inlet of the heater 1,

[0030] Among them, each of the heating systems 3 includes a venturi tube 4 and a heating tube 5, the venturi tube 4 and the heating tube 5 are connected in sequence front to back, the venturi tube 4 is connected to the gas collection pipe 11, the front and rear ends of the heating tube 5 are straight tubes, the middle part of the heating tube 5 is a U-shaped tube, and the two straight tubes are respectively connected to the front and rear ends of the U-shaped tube, and the connection relationship of the heating system 3 is configured as follows: the output end of the nth heating tube 5 is connected to the input end of the n+1th venturi tube 4.

[0031] Furthermore, the heater 1 contains fuel oil.

[0032] Furthermore, the temperature of the fuel oil is 200-400°C.

[0033] Furthermore, the gas collecting pipe 11 is provided with a first safety valve 12 , and a second safety valve 13 is provided between the pressure monitoring control valve 7 and the gas emergency treatment combustion device 8 .

[0034] Furthermore, a connection port 15 is provided on the top of the heater 1 .

[0035] A method for treating soil thermal desorption with added hot fluid and collected gas based on Venturi, characterized in that it comprises the following steps:

[0036] Step 1: Place the gas collection well and circulation pipe 6 at the appropriate location of the contaminated soil, select and inject heating fluid, such as fuel oil, based on the specific pollutants, check that the connections at each interface are tight, set the pressure monitoring control value, open the pressure monitoring control valve 7, close the second safety valve 13, and start the heater 1;

[0037] Step 2: When the temperature monitor shows that the heating fluid in the heater 1 reaches a preset temperature, which is selected based on the specific pollutant and is generally 200-400° C., the circulation pump 14 is started;

[0038] Step 3: The hot fluid generates negative pressure through the venturi tube 4. After the organic matter in the soil is heat-treated by the heating tube 5, the desorbed gas enters the circulation tube 6 through the gas collection well and the venturi tube 4 under the action of negative pressure suction. In the process of flowing with the hot fluid, part of the gas is dissolved in the hot fluid;

[0039] Step 4: As the system runs, the pressure monitoring control valve 7 reaches a predetermined pressure, at which time the second safety valve 13 is opened, and the excess gas is led to the gas emergency treatment combustion device 8;

[0040] Step 5: After the repair is completed, turn off the heater 1, close the first safety valve 12, open the connection port 15 on the top of the heater 1 and the pressure monitoring control valve 7, collect the fuel in the heater 1 and the remaining gas in the pipeline, and turn off the circulation pump 14 after the materials in the pipeline are collected. Example

[0041] like Figure 2 As shown, the Venturi-based soil thermal desorption additional heat fluid and collection gas processing system includes a heater 1, a circulation pump 14, a heating system 3, a circulation pipe 6, a pressure monitoring control valve 7, a temperature sensor 9, and a flow sensor 10, wherein the heating system 3 includes a Venturi tube 4 and a heating pipe 5.

[0042] The circulation pipe 6 is a U-shaped pipe, the lower part of which is inserted into the soil. The circulation pipe 6 in the soil is made of stainless steel metal material, and the part exposed outside the soil is covered with insulation cotton. The venturi tube 4 is made of stainless steel metal material, and the interface is an internal flange joint. The circulation pump 14 is a LQRY-hot oil pump (one is used and one is spare), the gas collection pipe 11 is a homemade porous stainless steel casing, and a threaded port is provided on the upper part to connect with the venturi tube 4, and the pressure monitoring control valve 7 is an A21W stainless steel valve.

[0043] In this embodiment, an exhaust gas emergency transportation and absorption device 16 is provided, and the absorbent is methanol. The exhaust gas emergency transportation and absorption device 16 is connected to the circulation pipe 6 through a pressure monitoring control valve 7 .

[0044] In this embodiment, a heating fluid emergency disposal device 17 is provided, one end of the heating fluid emergency disposal device 17 is connected to the heater 1, and the other end is connected to the accident collection tank 18. During the normal repair process, the safety valve from the heating fluid emergency disposal device 17 to the accident collection tank 18 is in a closed state.

[0045] The remediation object of this embodiment is benzene-contaminated soil. After treatment, a part of the soil with uniform contamination is selected for the embodiment test. The average contamination concentration is 220 mg / kg, the contaminated area is 20m*30m, and the depth is 2m. Ten effective soil heating sections are evenly placed in the contaminated area, eight gas collection pipes 11, the heating fluid is heat carrier oil, and the exposed part of the soil surface is sealed.

[0046] After 336 hours of treatment, the remaining soil and the cooled heat carrier oil were tested, and the average concentration of benzene in the soil was 27 mg / kg and the concentration of benzene in the oil was 1.23 g / L.

[0047] The above-mentioned Venturi-based soil thermal desorption method with added hot fluid and collected gas is used to implement in-situ soil thermal remediation treatment, including the following steps:

[0048] Step 1: Check that all interfaces are tightly connected, close the valve of the pressure monitoring control valve 7, and start the heater 1; when the temperature monitor shows that the heating fluid in the heater 1 reaches 300°C, start the circulation pump 14; the hot fluid generates negative pressure through the venturi tube 4, and the volatile organic matter on site is heat-treated by the heating tube 5. The desorbed gas enters the circulation tube 6 through the gas collection well and the venturi tube 4 under the action of negative pressure suction, and part of the gas dissolves in the hot fluid in the process of flowing with the hot fluid;

[0049] Step 2: After 336 hours, turn off the heater 1, open the valve between the heater 1 and the external liquid treatment device, open the pressure monitoring control valve 7, collect the heating fluid and the remaining gas in the pipeline, and turn off the circulation pump 14 after the materials in the pipeline are collected.

[0050] Step 3: The remaining soil and the cooled heat carrier oil were tested. The average concentration of benzene in the soil was 27 mg / kg, and the concentration of benzene in the oil was 1.23 g / L.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Venturi-based soil thermal desorption device for adding hot fluid and collecting gas, characterized in that: It includes a heater and several heating systems, wherein a temperature sensor is arranged in the heater, and the heating systems are connected in sequence, wherein the outlet of the heater is connected to the front end of an outlet pipe, a circulation pump is arranged at the front part of the outlet pipe, the rear end of the outlet pipe is connected to the input end of the frontmost heating system, and the output end of the rearmost heating system is connected to the front end of the circulation pipe, a pressure monitoring control valve is arranged at the front end of the circulation pipe, and the pressure monitoring control valve is connected to a gas emergency treatment combustion device, a flow sensor is arranged at the rear part of the circulation pipe, and the rear end of the circulation pipe is connected to the inlet of the heater, wherein each of the heating systems includes a venturi tube and a heating tube, wherein the venturi tube and the heating tube are connected in sequence front to back, wherein the venturi tube is connected to a gas collecting tube, the front and rear ends of the heating tube are straight tubes, the middle part of the heating tube is a U-shaped tube, and the two straight tubes are respectively connected to the front and rear ends of the U-shaped tube, and the connection relationship of the heating system is configured as follows: the output end of the nth heating tube is connected to the input end of the n+1th venturi tube, the heater is built with fuel oil, and a connection port is arranged on the top of the heater.

2. A Venturi-based soil thermal desorption and heat addition fluid and collection gas processing device according to claim 1, characterized in that: The temperature of the fuel oil is 200-400°C.

3. The Venturi-based soil thermal desorption and heat addition fluid and collection gas processing device according to claim 1, characterized in that: The gas collecting pipe is provided with a first safety valve, and a second safety valve is provided between the pressure monitoring control valve and the gas emergency treatment combustion device.

4. A Venturi-based soil thermal desorption method with added hot fluid and collected gas, characterized in that: The method comprises the following steps: Step 1: placing the gas collection pipe and the circulation pipe at a suitable position of the contaminated soil, selecting and injecting the heating fluid based on the specific pollutants, checking that the connections at each interface are tight, setting the pressure monitoring control value, opening the pressure monitoring control valve, closing the second safety valve, and starting the heater; Step 2: When the temperature monitor shows that the heating fluid in the heater reaches the preset temperature, which is selected based on the specific pollutant and is generally 200 ~ 400 ° C, start the circulation pump; Step 3: The hot fluid generates negative pressure through the Venturi tube. After the organic matter in the soil is heat-treated by the heating tube, the desorbed gas enters the circulation tube through the gas collection tube and the Venturi tube under the action of negative pressure suction. In the process of flowing with the hot fluid, part of the gas dissolves in the hot fluid; Step 4: As the system runs, the pressure monitoring control valve reaches a predetermined pressure, at which time the second safety valve is opened and the excess gas is directed to the gas emergency treatment combustion device; Step 5: After the repair is completed, turn off the heater, close the first safety valve, open the connection port on the top of the heater and the pressure monitoring control valve, collect the fuel in the heater and the remaining gas in the pipeline, and after the materials in the pipeline are collected, turn off the circulation pump.

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