Condensing separation system with automatic blockage cleaning function

Abstract

The utility model discloses a condensing separation system with automatic unblocking function is used to the treatment of in-situ thermal desorption extraction tail gas in soil remediation. The system comprises a gas inlet three-way valve, two parallel gas-liquid separators, two heat exchangers, three pressure sensors, a gas outlet three-way valve, a negative pressure fan, a liquid discharge pump and a cooling water three-way valve connected by pipelines. The system monitors the pressure difference between the gas-liquid separator and the intermediate pipeline in real time, automatically controls the synchronous switching of the gas inlet three-way valve, the gas outlet three-way valve and the cooling water three-way valve, thereby changing the flow path of the tail gas and the cooling water, and realizing the alternating operation of the two heat exchangers between the working state and the heating and unblocking state. The utility model can automatically remove the condensed solid pollutants in the heat exchanger without stopping the machine, effectively avoid the blockage, ensure the continuous and stable operation of the system, and significantly reduce the risk of secondary pollution.

Description

Technical Field

[0001] This utility model relates to the field of soil remediation technology, and in particular to a condensation separation system with automatic unblocking function for in-situ thermal desorption extraction of tail gas. Background Technology

[0002] Persistent organic pollutants (POPs) have attracted widespread international attention due to their characteristics of long-term persistence, bioaccumulation, semi-volatility, and high toxicity. They can migrate long distances in the atmosphere, water, and soil, ultimately entering the human body through the food chain. Studies have found that long-term chronic exposure to POPs may lead to cancer, damage to the central and peripheral nervous systems, disruption of the immune system, impaired fertility, and negative impacts on normal infant development. The effects of some POPs can persist for generations, posing a significant threat to human survival, reproduction, and sustainable development.

[0003] Thermal desorption (TDE) is a proven and widely used remediation technique for polluted sites containing pollutants (POPs). TDE removes volatile or semi-volatile organic pollutants by heating the contaminated soil. POPs remediation technologies can be categorized into in-situ remediation and ex-situ remediation based on the location of the remediation project. In-situ remediation refers to the on-site treatment of pollutants in the contaminated site; ex-situ remediation involves excavating the soil and then treating it.

[0004] The extraction tail gas of in-situ thermal desorption technology has a high temperature and contains a large amount of water vapor, making it difficult to treat the tail gas directly. Therefore, most of them use the condensation method to separate the gas and liquid, and then treat the condensed waste liquid and non-condensable tail gas separately.

[0005] Because pollutants in POPs-contaminated sites change with the products manufactured, and because various pollutants undergo unpredictable chemical reactions in the soil, as well as oxidation and reduction reactions by soil microorganisms, and because of the diverse types of pollutants and the high heterogeneity of the soil, site investigations cannot identify and eliminate all possible pollutants. Therefore, the exact composition of the exhaust gas extracted by in-situ thermal desorption technology is difficult to determine at the planning stage. Furthermore, the composition of the exhaust gas varies at different stages due to differences in soil temperature during the remediation phase of in-situ thermal desorption technology. If the exhaust gas contains components with a freezing point higher than the cooling temperature, it will inevitably clog the cooler, rendering the cooling lines unusable. Manual unclogging on-site necessitates equipment shutdown and will cause secondary pollution. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a condensation separation system with an automatic unclogging function. This system can automatically remove solid contaminants condensed inside the heat exchanger without shutting down the system, effectively preventing blockages.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: the system constructs two parallel and reversible process branches, and automatically controls the synchronous switching of three three-way valves for air inlet, air outlet and cooling water by comparing the pressure values ​​of three key points in real time, so as to realize the alternating operation of the two heat exchangers between the working state and the heating and unblocking state.

[0008] The condensation separation system with automatic unblocking function specifically includes:

[0009] Gas flow components: inlet pipe (1), inlet three-way valve (2), parallel gas-liquid separator 1 (3) and gas-liquid separator 2 (12), gas phase pipe 1 (5), heat exchanger 1 (6), intermediate connecting pipe (7), heat exchanger 2 (9), gas phase pipe 2 (10), outlet three-way valve (13), negative pressure fan (14), outlet pipe (15);

[0010] Pressure monitoring components: Pressure sensor 1 (4) for monitoring the pressure of gas-liquid separator 1 (3), intermediate pressure sensor (8) for monitoring the pressure of intermediate connecting pipe (7), and pressure sensor 2 (11) for monitoring the pressure of gas-liquid separator 2 (12).

[0011] Liquid handling components: 1# upper drain pipe (16), 2# upper drain pipe (17), 1# lower drain pipe (18), 2# lower drain pipe (19), 1# drain pump (20), 2# drain pump (21), main drain pipe (22);

[0012] Cooling system components: cooling water inlet pipe (23), cooling water outlet pipe (24), cooling water three-way valve (25);

[0013] The system controls the synchronous switching of the intake three-way valve (2), the exhaust three-way valve (13) and the cooling water three-way valve (25) through the detection signals of three pressure sensors, so as to realize the reversible operation of the exhaust gas process and the alternating unblocking of the heat exchanger.

[0014] Furthermore: The No. 1 gas-liquid separator (3) and the No. 2 gas-liquid separator (12) are filled with adsorption packing material, and the tank is equipped with a gas interface, a liquid outlet and a drain outlet.

[0015] Furthermore: the 1# pressure sensor (4), intermediate pressure sensor (8) and 2# pressure sensor (11) are used to detect the system pressure in real time; when the pressure difference between the 2# pressure sensor (11) and the intermediate pressure sensor (8) exceeds the set threshold, the control system switches the exhaust gas to flow sequentially through the 1# gas-liquid separator (3), the 1# heat exchanger (6), the 2# heat exchanger (9), and the 2# gas-liquid separator (12), while cooling water flows into the 2# heat exchanger (9); when the pressure difference between the 1# pressure sensor (4) and the intermediate pressure sensor (8) exceeds the set threshold, the control system switches the exhaust gas flow direction to the opposite direction, while cooling water flows into the 1# heat exchanger (6).

[0016] Furthermore: The No. 1 drain pump (20) and the No. 2 drain pump (21) are high-temperature slurry pumps used to discharge the condensate and melted liquid pollutants from the gas-liquid separator into the system.

[0017] Furthermore, the switching of the cooling water three-way valve (25) is linked with the switching of the exhaust gas three-way valve to ensure that the cooling water always flows to the heat exchanger that is currently in the condensation working state.

[0018] The workflow of the condensation separation system includes:

[0019] 1) The extracted exhaust gas enters the system through the inlet pipe (1);

[0020] 2) When the system starts operating or when the pressure difference between pressure sensor 2 (11) and intermediate pressure sensor (8) exceeds the set threshold, the system automatically switches the flow sequence of the extracted tail gas through the inlet three-way valve (2) and outlet three-way valve (13) as follows: gas-liquid separator 1 (3), pressure sensor 1 (4), gas phase pipe 1 (5), heat exchanger 1 (6), intermediate connecting pipe (7), intermediate pressure sensor (8), heat exchanger 2 (9), gas phase pipe 2 (10), pressure sensor 2 (11), gas-liquid separator 2 (12). Cooling water is switched to flow through heat exchanger 2 (9) through cooling water three-way valve (25).

[0021] 3) When the pressure difference between pressure sensor 1 (4) and intermediate pressure sensor (8) is greater than the set threshold, the flow sequence of the extracted tail gas is automatically switched through the inlet three-way valve (2) and outlet three-way valve (13) as follows: gas-liquid separator 2 (12), pressure sensor 2 (11), gas phase pipe 2 (10), heat exchanger 2 (9), intermediate pressure sensor (8), intermediate connecting pipe (7), heat exchanger 1 (6), gas phase pipe 1 (5), pressure sensor 1 (4), gas-liquid separator 1 (3). Cooling water is switched to flow through heat exchanger 1 (6) through cooling water three-way valve (25).

[0022] 4) The system repeats processes 2 and 3 above;

[0023] 5) During the above process, the tail gas separation liquid flows into the No. 1 gas-liquid separator (3) and the No. 2 gas-liquid separator (12) by gravity through the No. 1 upper drain pipe (16) and the No. 2 upper drain pipe (17), respectively.

[0024] 6) When the 1# gas-liquid separator (3) or the 2# gas-liquid separator (12) needs to drain, start the corresponding 1# drain pump (20) or 2# drain pump (21) and drain the liquid through the 1# lower drain pipe (18) or 2# lower drain pipe (19) to the main drain pipe (22).

[0025] Furthermore, when the system is in process 2 above, heat exchanger #2 (9) is in condensation mode, while heat exchanger #1 (6) is not in condensation mode, but is being heated by the high-temperature extraction tail gas. During this heating process, the crystals condensed and precipitated in heat exchanger #1 (6) in process 3 will be melted into liquid and enter gas-liquid separator #1 (3).

[0026] Furthermore, when the system is in process 3 above, heat exchanger #1 (6) is in condensation mode, while heat exchanger #2 (9) is not in condensation mode but is being heated by the high-temperature extraction tail gas. During this heating process, the solids condensed and precipitated in heat exchanger #2 (9) in process 2 will be melted into liquid and enter gas-liquid separator #2 (12).

[0027] Furthermore, the condensed solids from the liquid phase will be collected by the 1# drain pump (20) or the 2# drain pump (21) during the draining process and discharged into the main drain pipe (22) through the 1# lower drain pipe (18) or the 2# lower drain pipe (19).

[0028] Furthermore, the solids condensed from the liquid phase may re-condense in the No. 1 gas-liquid separator (3) or the No. 2 gas-liquid separator (12). Therefore, the No. 1 drain pump (20) and the No. 2 drain pump (21) need to be high-temperature resistant slurry pumps.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following significant beneficial effects:

[0030] 1. Through pressure sensor monitoring and automatic linkage control of the three-way valve, the system can automatically switch the flow direction of exhaust gas and cooling water without stopping the machine, so that the blocked heat exchanger enters the heating and descaling state, which completely solves the problem of having to stop the machine for manual cleaning due to heat exchanger blockage, and greatly improves the continuity and efficiency of soil remediation operations.

[0031] 2. The entire unblocking process is completed automatically in a closed system, avoiding the release of pollutants that may occur when the equipment is opened during manual cleaning, and significantly reducing the risk of secondary pollution and the health threat of personnel being exposed to harmful gases.

[0032] 3. This utility model does not rely on precise prediction of exhaust gas composition. It judges and performs unblocking through real-time differential pressure and can adapt well to the complex and dynamic working conditions of exhaust gas composition during in-situ thermal desorption repair, thus having high versatility.

[0033] 4. The design employs dual-path parallel operation with alternating operation, ensuring that temporary failures of a single component do not paralyze the entire system. Simultaneously, the automatic unblocking mechanism reduces the frequency of equipment disassembly and cleaning, as well as spare parts replacement costs, thereby lowering the long-term maintenance burden of the system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of this utility model, wherein: inlet pipe (1), inlet three-way valve (2), 1# gas-liquid separator (3), 1# pressure sensor (4), 1# gas phase pipe (5), 1# heat exchanger (6), intermediate connecting pipe (7), intermediate pressure sensor (8), 2# heat exchanger (9), 2# gas phase pipe (10), 2# pressure sensor (11), 2# gas-liquid separator (12), outlet three-way valve (13), negative pressure fan (14), outlet pipe (15), 1# upper drain pipe (16), 2# upper drain pipe (17), 1# lower drain pipe (18), 2# lower drain pipe (19), 1# drain pump (20), 2# drain pump (21), main drain pipe (22), cooling water inlet pipe (23), cooling water outlet pipe (24), cooling water three-way valve (25);

[0035] Figure 2 A schematic diagram showing the location of the tee for the exhaust gas to first pass through heat exchanger #1 and then through heat exchanger #2, and the flow direction of the exhaust gas and cooling water.

[0036] Figure 3 This diagram shows the location of the tee where the exhaust gas first passes through heat exchanger #2 and then through heat exchanger #1, along with the flow direction of the exhaust gas and cooling water. Detailed Implementation

[0037] The following detailed description of the embodiments of this utility model is provided in conjunction with the accompanying drawings. Through the interpretation of the three drawings, the structure of the system and the two automatically switching working modes are clearly demonstrated.

[0038] I. Basic System Components

[0039] As attached Figure 1As shown, the system of this utility model constitutes a reversible, dual-branch closed loop. Its basic connection relationship is as follows: the extracted exhaust gas enters from the inlet pipe 1 and is distributed to two parallel branches by the inlet three-way valve 2. The first branch connects sequentially to gas-liquid separator 3 (1#), pressure sensor 4 (1#), gas phase pipe 5 (1#), and heat exchanger 6 (1#); the second branch connects sequentially to gas-liquid separator 12 (2#), pressure sensor 11 (2#), gas phase pipe 10 (2#), and heat exchanger 9 (2#). The two branches merge through the intermediate connecting pipe 7, connect to the intermediate pressure sensor 8, and then pass through the outlet three-way valve 13 and the negative pressure fan 14, finally exiting the system through the outlet pipe 15.

[0040] The liquid handling section includes: Upper drain pipe 16 (No. 1) and Upper drain pipe 17 (No. 2) are respectively connected to the upper parts of the two gas-liquid separators; Lower drain pipe 18 (No. 1) and Lower drain pipe 19 (No. 2) are respectively connected to the bottom of the two gas-liquid separators and are driven by drain pump 20 (No. 1) and drain pump 21 (No. 2) to collect waste liquid and discharge it through the main drain pipe 22. The cooling water system consists of a cooling water inlet pipe 23, a cooling water three-way valve 25, and a cooling water outlet pipe 24, used to provide a cooling source to the heat exchanger. The gas-liquid separators can be filled with adsorption packing to enhance the separation effect.

[0041] II. Automatic Unblocking Process

[0042] The system automatically switches between two working modes by comparing the pressure difference between pressure sensor 4 (1#), intermediate pressure sensor 8, and pressure sensor 11 (2#), thereby achieving uninterrupted blockage removal.

[0043] 1. Process 1: Unblocking heat exchanger #1, starting operation of heat exchanger #2.

[0044] As attached Figure 2 As shown, when the system starts up, or when the pressure difference between pressure sensor 11 (2#) and intermediate pressure sensor 8 exceeds a set threshold, the system determines that the resistance on the 9-side of heat exchanger 2# has increased, potentially indicating blockage. At this time, the control system automatically performs a switching operation.

[0045] Exhaust gas flow direction: The intake three-way valve 2 and the exhaust three-way valve 13 are switched to make the exhaust gas flow sequentially through: 1# gas-liquid separator 3 → 1# gas phase pipe 5 → 1# heat exchanger 6 → intermediate connecting pipe 7 → 2# heat exchanger 9 → 2# gas phase pipe 10 → 2# gas-liquid separator 12.

[0046] Cooling water flow direction: The cooling water three-way valve 25 switches synchronously so that cooling water only flows into heat exchanger 9.

[0047] Operating status: In this mode, cooling water is introduced into heat exchanger 9, which is in condensation operation; while no cooling water is introduced into heat exchanger 6, which is heated by the high-temperature exhaust gas flowing through it and is in scale dissolution and blockage removal operation. The solid blockages that condensed in this heat exchanger in the previous cycle are melted and discharged after entering the gas-liquid separator 3 with the condensate.

[0048] 2. Process Two: Unblocking heat exchanger #2, starting heat exchanger #1.

[0049] As attached Figure 3 As shown, when the pressure difference between pressure sensor 4 (1#) and intermediate pressure sensor 8 exceeds the set threshold, the system determines that the resistance on the 6 side of heat exchanger 1# has increased. At this time, the system automatically switches to the reverse flow:

[0050] Tail gas flow direction: All three-way valves change state to completely reverse the tail gas flow direction, in the following order: 2# gas-liquid separator 12 → 2# gas phase pipe 10 → 2# heat exchanger 9 → intermediate connecting pipe 7 → 1# heat exchanger 6 → 1# gas phase pipe 5 → 1# gas-liquid separator 3.

[0051] Cooling water flow direction: The cooling water three-way valve 25 is switched so that cooling water flows only into heat exchanger 6#1.

[0052] Operating status: In this mode, cooling water is introduced into heat exchanger 6#1, which is in condensation operation; while no cooling water is introduced into heat exchanger 9#2, which is heated by high-temperature exhaust gas and is in scale dissolution and blockage removal operation, melting the solid blockages accumulated in process two.

[0053] By repeating the above "Process 1" and "Process 2", the system achieves automatic and alternating switching between the two heat exchangers in condensation and unblocking states, thereby ensuring that the system can operate continuously and stably for a long time and effectively deal with the complex and easily condensable extraction tail gas.

Claims

1. A condensation separation system with automatic unblocking function, characterized in that, include: Gas flow components: inlet pipe (1), inlet three-way valve (2), parallel gas-liquid separator 1 (3) and gas-liquid separator 2 (12), gas phase pipe 1 (5), heat exchanger 1 (6), intermediate connecting pipe (7), heat exchanger 2 (9), gas phase pipe 2 (10), outlet three-way valve (13), negative pressure fan (14), outlet pipe (15); Pressure monitoring components: Pressure sensor 1 (4) for monitoring the pressure of gas-liquid separator 1 (3), intermediate pressure sensor (8) for monitoring the pressure of intermediate connecting pipe (7), and pressure sensor 2 (11) for monitoring the pressure of gas-liquid separator 2 (12). Liquid handling components: 1# upper drain pipe (16), 2# upper drain pipe (17), 1# lower drain pipe (18), 2# lower drain pipe (19), 1# drain pump (20), 2# drain pump (21), main drain pipe (22); Cooling system components: cooling water inlet pipe (23), cooling water outlet pipe (24), cooling water three-way valve (25); The system controls the synchronous switching of the intake three-way valve (2), the exhaust three-way valve (13) and the cooling water three-way valve (25) through the detection signals of three pressure sensors, so as to realize the reversible operation of the exhaust gas process and the alternating unblocking of the heat exchanger.

2. The condensation separation system according to claim 1, characterized in that: The No. 1 gas-liquid separator (3) and the No. 2 gas-liquid separator (12) are filled with adsorption packing material, and the tank is equipped with a gas interface, a liquid outlet and a drain outlet.

3. The condensation separation system according to claim 1, characterized in that: The pressure sensor 1 (4), intermediate pressure sensor (8) and pressure sensor 2 (11) are used to detect the system pressure in real time. When the pressure difference between pressure sensor 2 (11) and intermediate pressure sensor (8) exceeds the set threshold, the control system switches the exhaust gas to flow sequentially through gas-liquid separator 1 (3), heat exchanger 1 (6), heat exchanger 2 (9), and gas-liquid separator 2 (12), while cooling water flows into heat exchanger 2 (9). When the pressure difference between pressure sensor 1 (4) and intermediate pressure sensor (8) exceeds the set threshold, the control system switches the exhaust gas flow direction to the opposite direction, while cooling water flows into heat exchanger 1 (6).

4. The condensation separation system according to claim 1, characterized in that: The No. 1 drain pump (20) and No. 2 drain pump (21) are high-temperature slurry pumps used to discharge the condensate and melted liquid pollutants from the gas-liquid separator into the system.

5. The condensation separation system according to claim 1, characterized in that: The switching of the cooling water three-way valve (25) is linked with the switching of the exhaust gas three-way valve to ensure that the cooling water always flows to the heat exchanger that is currently in the condensation working state.

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