Method and apparatus for cooling soil thermal desorption gas

Abstract

The application relates to a soil thermal desorption gas cooling method and equipment. After spray liquid is discharged from a spray tower, the spray liquid is introduced into a main water tank for water treatment, the treated spray liquid is guided from the main water tank into an air cooler for cooling, and the cooled spray liquid is guided into the spray tower to realize recycling. The number of the air coolers is at least two sets, and at least two sets of the air coolers work simultaneously. The air cooler is provided with a cleaning unit. The main water tank is provided with a secondary water tank, the secondary water tank is communicated with the main water tank, the spray liquid in the main water tank is partially introduced into the secondary water tank and temporarily stored in the secondary water tank. When an air cooler is in a cleaning state, the spray liquid in the secondary water tank is transported to the spray tower to keep the flow and temperature of the spray liquid in the spray tower stable. The soil thermal desorption gas cooling method and equipment realize self-sufficiency of the cooling liquid in the process operation under the premise of guaranteeing the stability of the soil thermal desorption gas cooling process.

Description

Technical Field

[0001] The present invention belongs to the technical field of pyrolysis desorption, and in particular relates to a method and equipment for cooling soil pyrolysis desorption gas. Background Art

[0002] Thermal desorption is an emerging technology for contaminated soil treatment that has been widely used in recent years. The pyrolysis gas from soil contains not only a large amount of dust but also a large amount of condensable gases, including gaseous water, oil, and organic pollutants. To recover these substances, spray towers are often used to cool these components for recycling, but this requires a large amount of cooling liquid. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a soil pyrolysis desorption gas cooling method and equipment, which can achieve self-sufficiency of cooling liquid in the process operation while ensuring the stability of the soil pyrolysis desorption gas cooling process.

[0004] In order to achieve the above object, the technical solution of the present invention is as follows:

[0005] The method for cooling soil pyrolysis desorption gas comprises the following steps: introducing soil pyrolysis desorption gas into a spray tower, and introducing spray liquid into the spray tower to spray cool the soil pyrolysis desorption gas; the condensable gas in the soil pyrolysis desorption gas is cooled and discharged from the spray tower along with the spray liquid; after the spray liquid is discharged from the spray tower, the spray liquid is introduced into a main water tank for water treatment; the sediment is discharged from the main water tank; the treated spray liquid is discharged from the main water tank and then connected to an air cooler for cooling; the cooled spray liquid is introduced into the spray tower for recycling; the air cooling There are at least 2 sets of air coolers and at least 2 sets of air coolers work at the same time; the air cooler is equipped with a cleaning unit; the cleaning unit includes a cleaning water tank and a cleaning pipeline, and the cleaning water tank is filled with cleaning liquid; the main water tank is equipped with an auxiliary water tank, which is connected to the main water tank, and the spray liquid in the main water tank is partially introduced into the auxiliary water tank and temporarily stored in the auxiliary water tank, and the auxiliary water tank is connected to the spray tower; when an air cooler is in the cleaning state, the spray liquid in the auxiliary water tank is transported to the spray tower to keep the spray liquid flow and temperature in the spray tower stable.

[0006] As an improvement, the auxiliary water tank is connected to the main water tank through an overflow pipe. When the spray liquid in the main water tank exceeds a certain liquid level, the spray liquid in the main water tank overflows into the auxiliary water tank and is temporarily stored in the auxiliary water tank.

[0007] As a further improvement, the air cooler is connected to a cleaning pipeline, and the cleaning pipeline is provided with a waste liquid channel connected to the main water tank.

[0008] The soil pyrolysis desorption gas cooling device described in the present invention includes a spray tower and a main water tank. The condensable gas in the soil pyrolysis desorption gas is cooled in the spray tower and discharged from the spray tower along with the spray liquid and gathered in the main water tank. The main water tank is provided with a sediment discharge pipeline. A spray liquid supply pipeline is provided between the spray tower and the main water tank. At least two sets of air coolers are connected to the spray liquid supply pipeline; the air cooler is equipped with a cleaning unit; the cleaning unit includes a cleaning water tank and a cleaning pipeline; the main water tank is equipped with an auxiliary water tank, which is connected to the main water tank. The spray liquid in the main water tank can be partially introduced into the auxiliary water tank and temporarily stored in the auxiliary water tank. The auxiliary water tank is connected to the spray tower.

[0009] As an improvement, the auxiliary water tank is connected to the main water tank through an overflow pipe. When the spray liquid in the main water tank exceeds a certain liquid level, the spray liquid in the main water tank overflows into the auxiliary water tank and is temporarily stored in the auxiliary water tank.

[0010] As a further improvement, the air cooler is connected to a cleaning pipeline, and the cleaning pipeline is provided with a waste liquid channel connected to the main water tank.

[0011] The inventive concept of this invention is that before thermal desorption, the soil needs to be pre-treated to ensure effective thermal desorption, adjusting its moisture content to between 20% and 30%. This high soil moisture content, specifically the high water vapor content in the thermally desorbed soil gas, is exploited to collect and utilize this water vapor, creating a closed-loop cooling system without the need for an additional cooling water source.

[0012] The beneficial effects of the present invention are:

[0013] (1) The water treatment operation of the main water tank is mainly to add flocculants. As the spraying is carried out, the water in the soil will converge into the main water tank along with the spray liquid, resulting in a large increase in the spray liquid. Therefore, the sediment discharge pipeline needs to be open frequently to discharge part of the spray liquid and flocculated sediments such as dust in time. The setting of the auxiliary water tank can lead part of the spray liquid to the auxiliary water tank and temporarily store it in the auxiliary water tank. The technical effect brought about is: the valve on the sediment discharge pipeline can be closed, and the outflow rate of sediment from the sediment discharge pipeline can be reduced, thereby increasing the contact time between the spray liquid and the flocculant, which is conducive to improving the flocculation effect, and at the same time making the treated spray liquid water quality purer, ensuring the quality of the water used for spraying. Preferably, the spray liquid in the water tank flows into the auxiliary water tank by overflow, so the spray liquid entering the auxiliary water tank is a relatively pure liquid located in the upper layer of the main water tank. The spray liquid in the auxiliary water tank is naturally cooled and reserved.

[0014] (2) At least two air coolers are connected in parallel on the spray liquid supply pipeline. Compared with the conventional "one in use and one standby" mode, in this application, all air coolers are fully open during normal operation, which improves the cooling efficiency of the spray liquid before reuse and reduces equipment investment. From another perspective, the design of at least two air coolers in this application is not based on the consideration of "one in use and one standby". Its starting point is: when one of the air coolers is closed, how to maintain the stability of various parameters of the spray liquid in the spray tower.

[0015] (3) When cleaning an air cooler, it is only necessary to shut down this air cooler. Since this air cooler no longer supplies the relatively low-temperature spray liquid, the spray liquid temporarily stored in the auxiliary water tank needs to be replenished to prevent the flow rate and temperature of the spray liquid in the spray tower from fluctuating significantly, thereby maintaining the stability of the spray process parameters and ensuring the spray effect.

[0016] (4) The air cooler is equipped with a cleaning unit, which is an existing technology. The cleaning pipeline is provided with a channel connected to the main water tank so that the impurities cleaned can be collected in the main water tank for treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of the invention;

[0018] Figure 2 Schematic diagram of the flow direction of the spray liquid at the air cooler;

[0019] Figure 3 Schematic diagram of the flow of cleaning fluid at one of the air coolers.

[0020] In the figure: 1. Spray tower; 2. Main water tank; 3. Auxiliary water tank; 4. Sediment discharge pipeline; 5. Spray liquid supply pipeline; 6. Air cooler; 7. Cleaning unit; 71. Cleaning water tank; 72. Cleaning pipeline; 73. Waste liquid channel. DETAILED DESCRIPTION

[0021] Example 1

[0022] The soil pyrolysis desorption gas cooling method described in the present invention is to introduce the soil pyrolysis desorption gas into the spray tower while introducing the spray liquid into the spray tower to spray cool the soil pyrolysis desorption gas, and the spray liquid is water. The temperature of the soil pyrolysis desorption gas is generally around 250°C. The condensable gas in the soil pyrolysis desorption gas is discharged from the spray tower along with the spray liquid after being cooled. After the spray liquid is discharged from the spray tower, the spray liquid is introduced into the main water tank for water treatment, and the sediment is discharged from the main water tank. The treated spray liquid is discharged from the main water tank and then connected to the air cooler for cooling. The cooled spray liquid is introduced into the spray tower for recycling; the number of the air coolers is at least 2 sets and at least 2 sets of air coolers work at the same time, and the air coolers are connected in parallel with each other. The flow direction of the spray liquid at the air cooler is shown in FIG. Figure 2 shown.

[0023] The air cooler is equipped with a cleaning unit; the cleaning unit includes a cleaning water tank and a cleaning pipeline. The cleaning water tank is filled with cleaning fluid. The air cooler is connected to the cleaning pipeline, and the cleaning pipeline is provided with a waste liquid channel connected to the main water tank. The flow direction of the cleaning fluid at one of the air coolers is shown in Figure 3 shown.

[0024] The main water tank is equipped with an auxiliary water tank, which is connected to the main water tank. The spray liquid in the main water tank is partially introduced into the auxiliary water tank and temporarily stored in the auxiliary water tank. The auxiliary water tank is connected to the spray tower; preferably, the auxiliary water tank is connected to the main water tank through an overflow pipe. When the spray liquid in the main water tank exceeds a certain liquid level, the spray liquid in the main water tank overflows into the auxiliary water tank and is temporarily stored in the auxiliary water tank.

[0025] When an air cooler is being cleaned, the spray liquid in the auxiliary water tank is transferred to the spray tower to maintain a stable flow and temperature within the tower. After heat exchange in the air cooler, the spray liquid typically cools to 30°C to 40°C. However, the temperature of the naturally cooled spray liquid in the auxiliary water tank is close to room temperature. Therefore, using the spray liquid in the auxiliary water tank instead of the air cooler provides a more effective cooling effect during the spraying process. Depending on operating conditions, each air cooler requires cleaning every 12 to 24 hours. After cooling the soil pyrolysis desorbed gases in the spray tower, the non-condensable gases typically reach a temperature of around 80°C. These non-condensable gases are then directed to the secondary combustion chamber for combustion.

[0026] like Figure 1As shown, the soil pyrolysis desorption gas cooling device of the present invention includes a spray tower 1 and a main water tank 2. The condensable gas in the soil pyrolysis desorption gas is cooled in the spray tower 1 and discharged from the spray tower 1 along with the spray liquid and gathered in the main water tank 2. The main water tank 2 is provided with a sediment discharge pipeline 4. A spray liquid supply pipeline 5 is provided between the spray tower 1 and the main water tank 2. The spray liquid supply pipeline 5 is connected to at least two sets of air coolers 6; the air coolers 6 are connected in parallel, and the spray liquid supply pipeline 5 branches out into several branches, each branch corresponding to a set of air coolers 6. The spray liquid coming out of the air coolers 6 is gathered and enters the spray tower 1. In this embodiment, the number of air coolers 6 is two sets. Figure 1 The two sets of air coolers 6 are drawn with lines of different thicknesses so that they can be clearly distinguished. The flow direction of the spray liquid at the air cooler is shown in FIG. Figure 2 shown.

[0027] The air cooler 6 is equipped with a cleaning unit 7; the cleaning unit 7 includes a cleaning water tank 71 and a cleaning pipeline 72. The cleaning water tank 71 is filled with cleaning liquid. The air cooler 6 is connected to the cleaning pipeline 72. The cleaning pipeline 72 is provided with a waste liquid channel 73 connected to the main water tank 2. The waste liquid channel 73 is used to introduce the cleaning waste liquid into the main water tank 2 for water treatment so as to achieve reuse. How to operate the cleaning operation of the air cooler 6 is common sense for those skilled in the art and will not be described in detail. The flow direction of the cleaning liquid at one of the air coolers is shown in FIG. Figure 3 shown.

[0028] The main water tank 2 is equipped with a secondary water tank 3, which is connected to the main water tank 2. The spray liquid in the main water tank 2 can be partially introduced into the secondary water tank 3 and temporarily stored therein. The secondary water tank 3 is also connected to the spray tower 1. The secondary water tank 3 is connected to the main water tank 2 via an overflow pipe. When the spray liquid in the main water tank 2 exceeds a certain level, the spray liquid in the main water tank 2 overflows into the secondary water tank 3 and is temporarily stored therein. The overflow structure of the secondary water tank 3 and the main water tank 2 is common knowledge to those skilled in the art. It is only necessary to open a hole at the upper edge of the main water tank 2 and connect it to the secondary water tank 3 with a pipe. It will not be described in detail here.

Claims

1. A method for cooling soil pyrolysis degassing, wherein the soil pyrolysis degassing is introduced into a spray tower, and a spray liquid is introduced into the spray tower to spray-cool the soil pyrolysis degassing. The condensable gas in the soil pyrolysis degassing is discharged from the spray tower along with the spray liquid after being cooled. The method is characterized in that: After the spray liquid is discharged from the spray tower, the spray liquid is introduced into the main water tank for water treatment, and the sediment is discharged from the main water tank. The treated spray liquid is discharged from the main water tank and then connected to the air cooler for cooling. The cooled spray liquid is introduced into the spray tower for recycling; there are at least 2 sets of air coolers and at least 2 sets of air coolers work at the same time; the air cooler is equipped with a cleaning unit; the cleaning unit includes a cleaning water tank and a cleaning pipeline, and the cleaning water tank is filled with cleaning liquid; the main water tank is equipped with an auxiliary water tank, which is connected to the main water tank, and the spray liquid in the main water tank is partially introduced into the auxiliary water tank and temporarily stored in the auxiliary water tank, and the auxiliary water tank is connected to the spray tower; when an air cooler is in the cleaning state, the spray liquid in the auxiliary water tank is transported to the spray tower to keep the spray liquid flow and temperature in the spray tower stable.

2. The soil pyrolysis desorption gas cooling method according to claim 1, characterized in that: The auxiliary water tank is connected to the main water tank through an overflow pipe. When the spray liquid in the main water tank exceeds a certain liquid level, the spray liquid in the main water tank overflows into the auxiliary water tank and is temporarily stored in the auxiliary water tank.

3. The soil pyrolysis desorption gas cooling method according to claim 1, characterized in that: The air cooler is connected to a cleaning pipeline, and the cleaning pipeline is provided with a waste liquid channel communicated with a main water tank.

4. Soil pyrolysis desorption gas cooling equipment, including a spray tower and a main water tank. The condensable gas in the soil pyrolysis desorption gas is cooled in the spray tower and then discharged from the spray tower along with the spray liquid and collected in the main water tank. The main water tank is equipped with a sediment discharge pipeline, which is characterized by: A spray liquid supply pipeline is provided between the spray tower and the main water tank, and at least two sets of air coolers are connected to the spray liquid supply pipeline; the air cooler is equipped with a cleaning unit; the cleaning unit includes a cleaning water tank and a cleaning pipeline; the main water tank is equipped with an auxiliary water tank, which is connected to the main water tank. The spray liquid in the main water tank can be partially introduced into the auxiliary water tank and temporarily stored in the auxiliary water tank, and the auxiliary water tank is connected to the spray tower; the auxiliary water tank is connected to the main water tank through an overflow pipe. When the spray liquid in the main water tank exceeds a certain liquid level, the spray liquid in the main water tank overflows into the auxiliary water tank and is temporarily stored in the auxiliary water tank; the air cooler is connected to the cleaning pipeline, and the cleaning pipeline is provided with a waste liquid channel connected to the main water tank.

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