JP5533036B2 - Soil heating system - Google Patents

Description

  The present invention relates to a soil heating system for heating soil in order to purify contaminated soil and improve soil.

  Conventionally, soil is purified by heating the soil. For example, Patent Document 1 describes a purification method in which soil is heated by reaction heat between quicklime and soil water to volatilize contaminants in the soil. Patent Document 2 describes a purification method for decomposing pollutants in soil by activating microorganisms capable of decomposing pollutants. In general, it is known that microorganisms are activated in a warm environment of about 40 ° C. Therefore, it is possible to enhance the purification ability by microorganisms by warming the soil. Patent Document 3 describes a purification method in which a heater is installed in the soil and the surrounding soil is heated by heating the heater. Furthermore, Patent Document 4 describes a purification method for heating surrounding soil by injecting high-pressure steam into contaminated soil.

  In addition to soil purification, soil warming may be performed from the viewpoint of ground improvement and crop growth promotion. That is, the soil may be heated for the purpose of promoting the solidification of the solidifying material with respect to the soil mixed with the solidifying material. In winter, the soil may be heated for the purpose of keeping the soil temperature at an appropriate temperature.

JP 2002-292361 A Japanese Patent Laid-Open No. 9-10552 Japanese Patent Laid-Open No. 2002-119953 Japanese National Patent Publication No. 4-501231

  By the way, in the purification method using the reaction heat of quicklime and soil water, it is difficult to continue heating the soil for a long time. Moreover, since calcium hydroxide is produced when quick lime reacts with water, there is a problem that the soil becomes alkaline.

  Moreover, in the purification method of heating the soil using a heater, only a very narrow range of soil near the heater can be heated. For this reason, in order to heat a wide range of soil, a plurality of heaters must be used.

  Furthermore, in the purification method in which high-pressure steam is injected into the soil, the steam condenses immediately after injection and the pressure becomes low. Therefore, as in the purification method using a heater, high-pressure steam is used to heat a wide range of soil. It is necessary to use many injection pipes. In addition, this purification method has a problem that the amount of water around the injection port becomes excessively high and the soil loosens. In addition, when high-pressure steam is generated by a boiler facility and distributed to a number of locations using ground piping, high-pressure steam will leak if the piping or joints are damaged. I have to come. In addition, the piping installed on the ground has a problem that efficiency is impaired because heat loss occurs even if the heat treatment is performed.

  Although it is conceivable to heat the soil by injecting heated air into the soil, it is difficult to heat a wide range of soil because the heat capacity of the air is too small.

  The present invention has been made in view of these circumstances, and an object thereof is to efficiently heat a wide range of soil over a long period of time.

In order to achieve the above object, the present invention provides:
A soil heating system for heating the soil by injecting steam into the soil,
A pressure vessel with a heater and a liquid receptacle inside, and
A gas introduction part for introducing a pressurized gas into the pressure vessel;
A liquid supply section for supplying a liquid to the receiving container;
The heater is configured to communicate with the pressure vessel via an injection valve, and the liquid supplied to the receiving vessel is supplied to the heater in a state where the injection valve is closed and the pressurized gas is introduced into the pressure vessel. A steam injection pipe for injecting the pressurized steam generated in the pressure vessel by heating at the soil from an injection port disposed in the soil by opening the injection valve;
It is characterized by having.

  According to the present invention, when the pressurized steam in the container is ejected from the ejection port, the pressurized steam immediately after the ejection is caused by the pressure generated by the expansion during the liquid evaporation and the pressure of the pressurized gas. In the soil. Thereafter, the heat is absorbed into the soil, and the liquid is condensed to reduce the pressure. However, since the pressure of the pressurized gas still acts, the steam can further travel in the soil. Thereby, a vapor | steam can be spread | diffused far from the case where only a vapor | steam is injected, and the soil of a wide range can be heated.

  And since the liquid used as the base of vapor | steam has a larger heat capacity than air, it can heat soil efficiently compared with the case where heated air is injected. Furthermore, in this invention, soil can be heated over a long period of time by injecting pressurized steam repeatedly.

  In the soil warming system of the present invention, while the gas vent valve is open, the inside and outside of the pressure vessel communicate with each other, while the gas vent valve is closed to provide a gas vent portion that shuts off the inside of the pressure vessel from the outside. When the gas vent valve is changed from the closed state to the open state after the injection valve is opened, the pressure valve is opened after the injection valve is opened and pressurized steam is injected toward the soil. The inside can be at the same pressure as the outside air. Here, if there is a residual pressure in the container, the pressure in the container may act on the liquid supply unit and be ejected. And the production | generation of the pressurized steam in the next cycle can be started early by making the inside of a pressure vessel the same pressure as external air.

  In the soil heating system of the present invention, when the injection port is provided on the lower end side surface of the steam injection pipe, the pressurized steam injected from the injection port diffuses upward so as to draw a parabola, so a wide range of soil Can be heated efficiently.

  In the soil heating system of the present invention, when the liquid supplied to the receiving container is water, pressurized water vapor is jetted, so the pH of the soil to be heated changes to the acidic side, It can suppress changing to the alkaline side.

In the soil heating system of the present invention, when an airtight sheet that covers the soil surface in an airtight state and an intake pipe that is embedded in the soil covered with the airtight sheet and sucks gas in the soil are provided Can efficiently recover contaminants in the soil that rise with pressurized steam.

  According to the soil heating system of the present invention, a wide range of soil can be efficiently heated over a long period of time.

It is a figure explaining the whole structure of a soil purification system. (A), (b) is a figure explaining the relationship between the saturated water vapor pressure and the amount of saturated water vapor | steam in an airtight container, and the temperature in a container. (A)-(d) is a figure explaining operation | movement of a soil purification system.

  Hereinafter, embodiments of the present invention will be described. In the present embodiment, a soil purification system that purifies soil by heating contaminated soil by spraying steam will be described as an example. This soil purification system is configured by adding a part for performing a harmful substance adsorption step to the soil heating system.

  The soil purification system shown in FIG. 1 includes a steam production injection device 1, an intake pipe 2, a suction pump 3, a gas-liquid separator 4, an adsorption tank 5, a compressor 6, and an air storage tank 7. ing. Of these parts, the steam production injection device 1, the intake pipe 2, the suction pump 3, the gas-liquid separator 4, and the compressor 6 correspond to a soil heating system. Therefore, it can be said that the soil purification system is obtained by adding the adsorption tank 5 to the soil heating system.

  The steam production / injection apparatus 1 includes a pressure vessel 11 that generates pressurized steam therein, an air supply pipe 12 (steam injection pipe) that is communicated with the pressure vessel 11 and embedded in soil G, and the pressure vessel 11 and the air supply pipe. And an injection valve 13 disposed between the two. The steam production / injection apparatus 1 guides the pressurized steam generated in the pressure vessel 11 to the air supply pipe 12 under the control of the injection valve 13 and injects it onto the soil G. The steam production / injection apparatus 1 will be described in detail later.

  The intake pipe 2 is for sucking the vapor that has risen up to the vicinity of the ground surface inside the soil G, and is constituted by a perforated pipe or a mesh-shaped underdrain pipe. A plurality of the intake pipes 2 are arranged side by side along the ground surface at a position on the ground surface side in the soil G. In the present embodiment, the ground surface portion of the region where the intake pipe 2 is provided is covered with the airtight sheet 8. By this airtight sheet 8, the vapor containing volatile harmful substances (for example, volatile organic compounds) can be recovered without leaking outside.

  The suction pump 3 is provided in the middle of an air supply pipe 9 that connects the intake pipe 2 and the gas-liquid separator 4, and sends out gas from the intake pipe 4 side to the gas-liquid separator 4 side. Therefore, when this suction pump 3 is operated, the vapor that has risen in the soil G is sucked into the intake pipe 2. The sucked steam is sent to the gas-liquid separator 4 through the air supply pipe 9.

  The gas-liquid separator 4 is a device that separates moisture from the gas, and is configured by a knockout drum, for example. The gas after the moisture is separated is sent to the adsorption tank 5. On the other hand, the separated water (separated water) may contain a small amount of harmful substances such as organic chlorine compounds, and cannot be discharged into the sewer as it is. For this reason, the separated water is rendered harmless by passing activated carbon for water treatment or the like, and then discharged.

  The adsorption tank 5 is an apparatus for removing harmful substances contained in the gas, and for example, an activated carbon adsorption tank is used. This activated carbon adsorption tank has an adsorption chamber filled with activated carbon, and brings the gas introduced from the inlet into contact with the activated carbon. By contact with activated carbon, volatile harmful substances contained in the gas are adsorbed on the activated carbon. And the gas after passing activated carbon is discharged | emitted from a discharge port.

  The compressor 6 is a device that compresses the gas discharged from the adsorption tank 5. Here, the gas discharged from the adsorption tank 5 is harmless low-humidity air because moisture is removed by the gas-liquid separator 4 and harmful substances are adsorbed by the adsorption tank 5. The air compressed by the compressor 6 is stored in the air storage tank 7 as pressurized air.

  The air storage tank 7 stores the pressurized air sent from the compressor 6. The pressurized air is stored at a specified pressure that is higher than the internal pressure of the pressure vessel 11 of the steam production / injection apparatus 1. And it sends to the pressure vessel 11 at the time of the production | generation of pressurized steam.

  Next, the steam production / injection apparatus 1 will be described in detail.

  The steam production / injection apparatus 1 includes a pressure vessel 11, an air supply pipe 12, an injection valve 13, an air introduction part 14 (gas introduction part), a water tank 15, a water supply valve 16, and an air vent part 17 (gas release part). Part) and a safety valve 18.

  The pressure vessel 11 is a part that generates pressurized steam as described above. In the present embodiment, the one having a volume of about 10 L and a withstand pressure of about 7 atm is used. Since the pressure vessel 11 has a high temperature of 100 ° C. or higher as will be described later, rock wool, glass wool, ceramic fibers, etc. are formed in, for example, a blanket shape on the outer surface or inner surface or inner / outer surface of the container for the purpose of minimizing heat loss. Wear warm insulation material. In the internal space of the pressure vessel 11, a water receiving vessel 11a and an electric heater 11b are provided. The water receiving container 11a is a portion that receives water supplied from the water tank 15, and corresponds to a liquid receiving portion. The water receiving container 11a is constituted by, for example, a metal tray-like member having an upper surface opened.

  The electric heater 11b generates heat when energized and heats it to a temperature higher than the boiling point of water. The electric heater 11b is disposed inside the water receiving container 11a. For this reason, when the electric heater 11b is heated after water is supplied, the water in the water receiving container 11a evaporates and the inside of the pressure container 11 is filled with steam. As will be described later, in the steam production / injection apparatus 1, the pressurized air is supplied to the pressure vessel 11 and then the electric heater 11 b is heated. For this reason, the output of the electric heater 11b is determined to such an extent that the water supplied to the water receiving container 11b can be heated to a temperature at which the water evaporates even under pressure by pressurized air.

  The air supply pipe 12 is a member corresponding to a steam injection pipe, and is configured as a cylindrical member that communicates with the pressure vessel 11 via an injection valve 13. When the steam production / injection apparatus 1 is used, most of the air supply pipe 12 except the upper end is embedded in the soil G. Further, the lower end of the air supply pipe 12 is closed by a lid member, and an injection port 12a for injecting steam is provided on the lower end side surface. The length and thickness of the air supply pipe 12 and the size and number of the injection ports 12a are determined according to the pressure of the pressurized steam, the state of the soil G, and the like.

  The injection valve 13 is disposed between the pressure vessel 11 and the air supply tube 12 as described above, and communicates the pressure vessel 11 and the air supply tube 12 in the open state, and the pressure vessel 11 and the air supply tube 12 in the closed state. And shut off. The injection valve 13 can electrically control the open / close state from the outside.

  The air introduction part 14 is a part for introducing pressurized air into the pressure vessel 11, and has an air introduction pipe 14a and an air introduction valve 14b. One end of the air introduction pipe 14 a is connected to the side surface of the pressure vessel 11, and the other end is connected to the air supply pipe 9 from the air storage tank 7. The air introduction valve 14b is provided in the middle of the air introduction pipe 14a, and allows the flow of pressurized air to the pressure vessel 11 side in the open state, and to the pressure vessel 11 side of the pressurized air in the closed state. To block the flow. The air introduction valve 14b can also be electrically controlled from the outside by the control unit.

  The water tank 15 is a part that stores water that is a base of steam, and serves as a water supply unit (liquid supply unit) together with the water supply valve 16 and the water supply pipe 19. In the present embodiment, the water tank 15 is disposed above the ceiling of the pressure vessel 11. The bottom of the water tank 15 and the ceiling of the pressure vessel 11 are connected by a water supply pipe 19. The water supply pipe 19 is a member for supplying the water stored in the water tank 15 into the pressure vessel 11. And the water supplied to the pressure vessel 11 from the water supply pipe 19 falls inside the pressure vessel 11 and is stored in the water receiving vessel 11a.

  The water supply valve 16 is provided in the middle of the water supply pipe 19 and controls the supply of water from the water tank 15 to the pressure vessel 11. The water discharged from the water supply pipe 19 fills a water volume (not shown). When the water volume is filled with a specified amount of water, the specified amount of water falls into the water receiving container 11a. The water supply valve 16 is configured by, for example, an electromagnetic valve, and the opening / closing operation is electrically controlled from the outside by a control unit. Therefore, by controlling the water supply valve 16, the start of water supply, the end of water supply, and the amount of water supply can be controlled.

  The air vent part 17 is a part for communicating the inside of the pressure vessel 11 to the outside or blocking the inside of the pressure vessel 11 from the outside, and has an air vent pipe 17a and an air vent valve 17b. The air vent pipe 17a has one end connected to the side surface of the pressure vessel 11 and the other end open to the atmosphere. Further, the air vent valve 17b is provided in the middle of the air vent pipe 17a, and communicates the inside of the pressure vessel 11 to the outside in the open state and blocks the inside of the pressure vessel 11 from the outside in the closed state. The air vent valve 17b is also electrically controlled from the outside by the controller.

  The safety valve 18 is for preventing a problem that the internal pressure of the pressure vessel 11 becomes excessively large. The safety valve 18 is attached to the pressure vessel 11 via a valve attachment pipe 20. And when the internal pressure of the pressure vessel 11 is below a threshold value, it will be in a closed state, and if this threshold value is exceeded, it will switch to an open state. By this operation, the internal pressure of the pressure vessel 11 is maintained below the threshold value. In the present embodiment, since the pressure vessel 11 having a pressure resistance of 7 atm is used, the threshold value is set to a value lower than 7 atm. Thereby, the internal pressure of the pressure vessel 11 is adjusted so as not to exceed 7 atmospheres. The safety valve 18 is a mechanism that automatically opens and releases the internal pressure when the internal pressure exceeds a specified internal pressure (here, 7 atm).

  In this steam production / injection apparatus 1, as described above, after introducing pressurized air into the pressure vessel 11, the water receiving vessel 11 a is heated by the electric heater 11 b to generate pressurized steam. Here, the amount of heat that the pressurized steam has will be described.

  When examining the amount of heat of the pressurized steam, as an illustrative example, processing conditions are defined as follows. That is, the volume of the pressure vessel 11 is 10 L, and the amount of water supplied to the water receiving vessel 11a is 10 g. Then, by introducing the pressurized air, the pressure of the pressure vessel 11 before heating (20 ° C.) is set to 2 atm (0.2 MPa). The internal temperature of the pressure vessel 11 before heating is 20 ° C., and the temperature is increased to 150 ° C. with the pressure vessel 11 sealed.

The pressure inside the pressure vessel 11 under this condition will be examined. First, consider the partial pressure of steam. As shown in FIGS. 2A and 2B, the saturated water vapor pressure at a temperature of 150 ° C. is 5000 hPa, and the saturated water vapor amount is 2500 g / m ³ . From this figure, it can be seen that if the pressure vessel 11 is 1 m ³ , 2.5 kg of water can be made into steam, and the pressure in the vessel at that time becomes 0.5 MPa (= 5000 hPa). In this embodiment, since the 10 L pressure vessel 11 is used, if 25 g of water is vaporized at a temperature of 150 ° C., the pressure inside the vessel becomes 0.5 MPa. Since the amount of water to be evaporated is 10 g under the above-described processing conditions, the vapor partial pressure when this amount of water is evaporated is 0.2 MPa from the following equation (1).
Steam partial pressure = 0.5MPa x (10g / 25g) = 0.2MPa (1)

Next, the air partial pressure is examined. Under the processing conditions described above, the air pressure before heating is 0.2 MPa. And since the air in a container expand | swells by heating, the pressure is raised. The air partial pressure after expansion is about 0.3 MPa from the following equation (2).
Air partial pressure = 0.2MPa x (273K + 150K) / (273K + 20K) ≒ 0.3MPa (2)

  The container internal pressure is 0.5 MPa because it is a value obtained by adding the vapor partial pressure and the air partial pressure. Here, if the amount of water is increased, the partial pressure of the steam is increased, so that the pressure in the container is increased. If the amount of water is decreased, the partial pressure of the steam is decreased, so that the pressure in the container is decreased. That is, the pressure in the container can be adjusted by adjusting the amount of water to be evaporated. Moreover, the pressure in a container can be adjusted by adjusting the setting value of heating temperature.

  Next, the amount of heat required for heating will be examined. Here, the amount of heat related to the heating of water and the amount of heat related to the heating of dry air are considered separately.

The amount of heat related to the heating of water is the sum of the evaporation heat of water and the specific heat of water. For this reason, as shown to following Formula (3), calorie | heat amount will be 6690cal. The latent heat of vaporization of water at 100 ° C. was set to 539 cal / g.
Calorie (water) = 10g x 539cal / g + 10g x (150 ° C-20 ° C) x 1cal / g / ° C = 6690cal… (3)

The amount of heat related to the heating of dry air is about 578 cal as shown in the following equation (4). The specific gravity of air was 1.3 g / L / atm, and the constant volume specific heat of dry air was 0.171 cal / g / ° C.
Amount of heat (dry air) = 10 L x 1.3 g / L / atm x 2 atm x (150 ° C-20 ° C) x 0.171 cal / g / ° C ≒ 578 cal (4)

  Accordingly, the total amount of heat is 7268 cal (= 30526 J), which corresponds to the amount of heat when heated by a 1000 W heater for about 30 seconds. For this reason, if a heater with an output larger than 1000 W is used, water can be evaporated in a time shorter than 30 seconds. Here, when the amount of heat related to the heating of water and the amount of heat related to the heating of dry air are compared, the amount of heat of water is 10 times or more larger than the amount of heat of dry air. From this, it can be seen that water also functions as an element for increasing the amount of heat in the pressurized steam.

Assuming that all the steam in the pressure vessel 11 is injected from the injection port 12a and used for warming the soil having a temperature of 15 ° C. It can be said that the soil can be heated up to 40 ° C. The specific heat of the soil was 0.53 cal / g / ° C.
Amount of soil to be heated = 7268 cal ÷ 0.53 [cal / g / ° C] ÷ (40 ° C-15 ° C) ≒ 550 g ... (5)

For example, consider a case where soil having a diameter of 2 m, a depth of 5 m, a volume of 15.7 m ³ and a mass of 23.6 tons is heated from 15 ° C. to 40 ° C. In this case, as shown in the following equation (6), the soil having a mass of 23.6 tons can be heated by repeating about 42900 injections. If injection is repeated once every 30 seconds, the required number of days is about 15 days. Further, the amount of water required is 429 L as shown in the following equation (7). Furthermore, the ratio of the volume of the sprayed steam and the volume of the soil to be heated is 429 m ³ as shown in the following equations (8) and (9), and the ratio is about 27 times.

Number of repetitions = 23.6 tons x 1000 [kg / ton] ÷ 0.55 [kg / time] ≒ 42900 times (6)
Required amount of water = 42900 times × 0.01 [L / time] ≒ 429L ... (7)
Steam volume = 42900 times × 0.01 [m ³ / time] ≒ 429 m ³ (8)
Ratio = 429m ³ ÷ 15.7m ³ ≒ 27 times ... (9)

  Accordingly, by using the steam production / injection apparatus 1 of the present embodiment, a large amount of soil having a mass of 23.6 tons can theoretically be heated in a period of about 15 days, and water required for heating is required. It can be understood that the total amount of is reduced to about 430L.

  Next, with reference to FIG. 3, the heating of the soil G by a soil purification system is demonstrated.

  In this soil purification system, first, as shown in FIG. For this reason, the air vent valve 17b is opened. Further, the water supply valve 16 is opened, and a specified amount (10 g) of water is supplied to the water receiving container 11a. At this time, the injection valve 13, the air introduction valve 14b, and the safety valve 18 are closed.

  When water is supplied to the water receiving container 11 a, pressurized air is introduced into the pressure container 11. In this case, as shown in FIG. 3B, after the water supply valve 16 and the air vent valve 17b are closed, the air introduction valve 14b is opened. Here, in this embodiment, since the inside of the pressure vessel 11 is atmospheric pressure and the pressurized air stored in the air storage tank 7 is a specified pressure, the pressure vessel is determined depending on the opening time of the air introduction valve 14b. The inside of 11 can be made into a desired pressure. In the present embodiment, the air introduction valve 14b is opened over a period in which the inside of the pressure vessel 11 is 2 atm.

  If pressurized air is introduced into the pressure vessel 11, the water in the water receiving vessel 11a is evaporated. In this case, as shown in FIG. 3C, the air heater 11b is energized after the air introduction valve 14b is closed. Thereby, the water receiving container 11a is heated, the water in the container evaporates, and the inside of the pressure container 11 is filled with the pressurized steam V.

  If the inside of the pressure vessel 11 is filled with the pressurized steam V, the pressurized steam V is injected. That is, the injection valve 13 is opened, and the pressurized steam V is injected toward the soil G from the injection port 12a.

  Here, in this embodiment, when the pressurized steam V is generated, the pressurized air is introduced into the pressure vessel 11 before the water is heated. For this reason, even if the temperature of the pressurized steam V injected from the injection port 12a falls and aggregation occurs, the pressure accompanying the pressurized air remains, and the pressurized steam V further advances in the soil G. Therefore, it is possible to diffuse the steam farther than in the case where the steam is simply injected, and it is possible to heat the soil G in a wide range. Moreover, the malfunction that much water aggregates in the vicinity of the injection nozzle 12a and the ground becomes loose can also be suppressed.

  And since the air containing steam has a larger heat capacity than the dry air, the soil G can be heated more efficiently than in the case of injecting heated dry air. Further, since the pressurized steam V is instantaneously injected, even if an air passage can be made in the soil G due to the progress of the steam, the soil returns by reaction and the air passage is blocked. As a result, there is a problem that the air passage is formed in a certain portion, that is, only the periphery of the fixed air passage is heated compared to the other portions, and the temperature of the soil G is uneven. Can be suppressed. As a result, the soil G can be evenly heated.

  The pressurized steam V injected into the soil G rises inside the soil G. Here, since the injection port 12a is provided in the lower end side surface of the steam injection pipe, as shown by the arrow in FIG. 3D, the pressurized steam V injected from the injection port 12a is upward so as to draw a parabola. To spread. For this reason, a wide range of soil G can be efficiently heated. And in this embodiment, since water is evaporated, it can suppress that pH changes about the soil G of warming object to the acidic side, or it changes to the alkaline side.

  When the pressurized steam V rises, volatile harmful substances contained in the soil G also rise in the soil G together with the pressurized steam V. These pressurized steam V and harmful substances are sucked into the intake pipe 2 near the ground surface. Thereafter, water is separated by the gas-liquid separator 4 and harmful substances are adsorbed by the adsorption tank 5. The air from which moisture and harmful substances have been removed is compressed by the compressor 6 and stored in the pressure vessel 11 as pressurized air. Pressurized air stored in the pressure vessel 11 is supplied to the pressure vessel 11 and used to generate pressurized steam for the next cycle.

  In the next cycle, the operation described with reference to FIGS. 3A to 3D is performed. Here, after the pressurized steam V is injected from the injection port 12a, the air vent valve 17b is opened prior to the introduction of the pressurized air, and the inside of the pressure vessel 11 is returned to the atmospheric pressure. Can be introduced quickly. That is, by keeping the pressure in the pressure vessel 11 substantially equal to the atmospheric pressure, the steam in the pressure vessel 11 is prevented from flowing into the water tank 15 when the water supply valve 16 is opened, and free from above. Water can be reliably supplied by dropping. As a result, the generation of the pressurized steam V can be started early.

  Thereafter, the generation and injection of the pressurized steam V are repeated and the soil G is heated. For this reason, the soil G can be heated over a long period of time. The amount of water used in one injection is as small as about 10 g (10 cc). For this reason, the replenishment frequency of the water to the water tank 15 can also be decreased, and the burden on the operator is small.

=== Other Embodiments ===
The above description of each embodiment is for facilitating the understanding of the present invention, and does not limit the present invention. The present invention can be changed and improved without departing from the spirit and purpose of the present invention, and the present invention naturally includes equivalents thereof.

  First, regarding the liquid for generating steam, water is used in the above-described embodiment, but the present invention is not limited to this. For example, ethanol may be used. Further, when the soil G is heated for the purpose of activating the microorganisms for purification, nutrients for microorganisms may be mixed in the liquid for generating steam.

  Further, when supplying compressed air, a compressor may be connected instead of the air storage tank 7, or pressurized nitrogen gas may be used instead of compressed air.

  Furthermore, the volume of the pressure vessel 11 and the length and thickness of the air supply pipe 12 are not limited to those of the above-described embodiment, and can be appropriately set according to the state of the soil G.

  In the above-described embodiment, the soil purification system has been described as an example. However, the present invention is not limited to this. For example, a system that warms the soil G for ground improvement may be used, or a system that warms the soil G for promoting the growth of crops. When the soil G is heated to promote the growth of the crop, the nutrients of the crop may be mixed into the steam generating liquid.

DESCRIPTION OF SYMBOLS 1 Steam production injection apparatus 2 Intake pipe 3 Suction pump 4 Gas-liquid separator 5 Adsorption tank 6 Compressor 7 Air storage tank 8 Airtight sheet 9 Air supply piping 11 Pressure vessel (11a Water receiving vessel, 11b Electric heater)
12 Air supply pipe (12a injection port)
13 Valve for injection 14 Air introduction part (14a Air introduction pipe, 14b Air introduction valve)
15 Water tank 16 Water supply valve 17 Air vent part (17a Air vent pipe, 17b Air vent valve)
18 Safety valve 19 Water supply pipe 20 Valve mounting pipe G Soil V Pressurized steam

Claims (5)

A soil heating system for heating the soil by injecting steam into the soil,
A pressure vessel with a heater and a liquid receptacle inside, and
A gas introduction part for introducing a pressurized gas into the pressure vessel;
A liquid supply section for supplying a liquid to the receiving container;
The heater is configured to communicate with the pressure vessel via an injection valve, and the liquid supplied to the receiving vessel is supplied to the heater in a state where the injection valve is closed and the pressurized gas is introduced into the pressure vessel. A steam injection pipe for injecting the pressurized steam generated in the pressure vessel by heating at the soil from an injection port disposed in the soil by opening the injection valve;
A soil heating system characterized by comprising: A degassing part that allows the inside and outside of the pressure vessel to communicate with each other when the degassing valve is open, and shuts off the inside of the pressure vessel from the outside when the degassing valve is closed;
The soil heating system according to claim 1, wherein the degassing valve is converted from a closed state to an open state after the injection valve is opened.   The soil heating system according to claim 1 or 2, wherein the injection port is provided on a lower side surface of the steam injection pipe.   The soil heating system according to any one of claims 1 to 3, wherein the liquid is water. An airtight sheet covering the soil surface in an airtight state;
The soil heating system according to any one of claims 1 to 4, further comprising: an intake pipe embedded in the soil covered with the airtight sheet and configured to suck in the gas in the soil. .

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