JP2005287421A - Apparatus for disinfecting soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for disinfecting soil designed to be widely applied even to the soil of general agricultural land and retaining excellent fungicidal and disinfecting effects over a long period. <P>SOLUTION: A fryer 1 is composed of a vessel 3 in which an edible oil 3 is contained and a heater 4 for heating the vessel 3. The edible oil 2 which is a heating medium is heated to increase the temperature to 100-230°C. Heat pipes 12 forming a part of a looped pipeline 19 are provided in a forward pipe 8 and a return pipe 10 mounted on the fryer 1 and embedded in the soil 23. The edible oil 2 is circulated to heat the underground to ≥90°C. Thereby, the soil is sterilized and disinfected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a soil disinfecting apparatus that circulates a high-temperature heat medium through a heat pipe embedded in soil to heat and disinfect the soil at a high temperature.

  Conventionally, the soil of farmland is easily contaminated by pathogenic bacteria, viruses and pests, and therefore it is necessary to disinfect the soil periodically. In this case, chemicals such as methyl bromide are often sprayed on the soil for disinfection. Disinfecting the soil with drugs such as methyl bromide is unavoidable for environmental destruction and adverse effects on the human body, so the use of methyl bromide and the like is prohibited in 2005.

  On the other hand, there is a method using hot water as a method of performing soil disinfection without using a chemical. For example, in Patent Document 1, a pipe is embedded in the soil, and the temperature of the soil is raised by using solar heat and underground heating in combination with hot water or hot liquid (ethylene glycol) at 50 ° C. in the pipe. A method for thermal disinfection of soil is disclosed. Patent Document 2 describes a technique for sterilizing and disinfecting hot water on soil in a field.

JP 2000-184828 (2nd page-3rd page, Fig. 1-Fig. 2) Japanese Patent Laid-Open No. 2003-129 (Page 2 to Page 3, FIG. 1 to FIG. 2)

  However, in the soil thermal disinfection method described in Patent Document 1, it is necessary to set the underground temperature to 18 ° C. to 20 ° C. by passing hot water or hot liquid (liquid having a low boiling temperature) of about 50 ° C. through the pipe. Both solar heat introduction and underground heating facilities are indispensable and can only be used for soil in greenhouses such as plastic houses. Moreover, in the technique of patent document 2, since hot water is spread | dispersed and osmose | permeated in the ground from the soil surface, a lot of hot water is required, energy loss is large, and there is a difficulty in sustainability of the sterilization effect. There is a problem that a long-term sterilization effect cannot be expected.

  In order to achieve this object, the soil disinfecting apparatus according to the present invention embeds a heat pipe in which heat medium circulates in the soil, and includes heating means for heating the heat medium to 100 ° C. to 230 ° C. An edible oil is used as a medium.

  According to the present invention, the underground temperature can be heated to 90 ° C. or higher using high-temperature edible oil, and pathogenic bacteria that inhabit the soil can be almost killed. In particular, there is an excellent effect that a high disinfecting action can be obtained for a long time even in soil of general farmland. In addition, the edible oil used in circulation is inexpensive and can be heated quickly with a small amount of heat. Even if the edible oil leaks from the heat pipe, it is safe and has little damage to the soil environment or the human body. is there.

  The present invention enables soil disinfection without spraying chemicals so as not to cause environmental destruction of farmland or damage to human bodies. Killing pathogens that contaminate soil without using chemicals leads to normal growth of crops and improvement of commercial value, and continuous cultivation of crops is also possible. The present inventor has paid attention to the heat treatment method as a method for sterilizing and disinfecting soil, and has conducted extensive research. As the heating means, a heat pipe, for example, a heating pipe that generates infrared electromagnetic waves or ultrasonic waves (trade name “c-tube”, manufactured by Kajiura Co., Ltd.) can be used. As the heat medium circulating in the heat pipe, an edible oil that can be sent out and circulated at a low pressure is selected so that damage to the surroundings can be minimized even if it leaks outside the pipe. The heat pipe is buried at a depth of about 300 mm from the ground surface.

  At the time of heat disinfection, the soil contains an appropriate amount of moisture, and a heat insulating sheet is placed on the soil. The cooking oil is heated to 100 ° C. to 230 ° C. by a heating means (flyer), and sent to a metal heat pipe, for example, a heat radiating pipe having a vacuum chamber, in a low pressure state by a heat-resistant circulation pump. The cooking oil sent to the heat pipe is heated and circulated in the ground, and then returned to the heating means for reuse. Circulating edible oil through heat pipes buried in soil enables safe dry disinfection in a short time. Some pathogenic bacteria that contaminate the soil do not die at 90 ° C. or lower, so that the soil temperature is raised to 90 ° C. or higher in order to obtain a complete disinfecting action of the pathogenic bacteria and the like. When the soil temperature exceeds 90 ° C., pathogenic fungi such as gray mold fungus and broad bean leaf fungus, pests such as root-knot nematode, and viruses such as cucumber green spot mosaic virus are completely killed.

  In order to raise soil temperature to 90 degreeC or more, it is necessary to make the temperature of the heat medium sent to a heat pipe into 100 to 230 degreeC. For this reason, the heating medium is not possible with warm water or steam, and edible oil having a boiling point higher than that of water is used. A so-called oil-liquid circulation system is adopted. The main reasons for adopting the oil-liquid circulation method are that the material cost of edible oil is low, that no serious damage occurs even if edible oil leaks from the pipe, and that the specific heat of edible oil is small, resulting in high energy saving effect during heat treatment It can be obtained.

  Heat pipes are usually installed in parallel on the target farmland, and are formed into a closed type piping system with a recirculating forward path and a return path. For the connection part of the heat pipe, a connector with a check valve is used in consideration of workability and safety at the time of removal, thereby preventing oil leakage and oil deterioration. Here, the cause of oil deterioration is mainly an oxidation reaction and a heating action. In particular, oxygen in the air, high temperature, light, and the like hit the oil, which causes deterioration of the oil due to thermal oxidation or the like. Such a change occurs suddenly at 230 ° C. or higher. Therefore, in the present invention, the heating temperature of the edible oil is kept in the range of 100 ° C. to 230 ° C., preferably 200 ° C. to 220 ° C., in order to prevent deterioration of the oil due to thermal oxidation or the like.

  By the above heating method, the soil temperature from the ground surface to a depth of 500 mm can be raised to 90 ° C. or higher. In farmland cultivation, the soil is usually dug only up to 300 mm, so the soil in the cultivation area can be safely dried and disinfected. By putting microorganisms and fertilizers necessary for the plant to be planted in the farmland after disinfection, it is possible to grow crops in the best soil condition. In addition, when the soil is dug beyond the depth of 500 mm, many anaerobic pests inhabit the area of 500 mm depth, but even if anaerobic pests inhabit, it is within 500 mm from the surface. If you dig a shallow part of the burial and embed a heat pipe, there will be no negative impact on planting and growth.

  As the oil circulating in the heat pipe, it is preferable to use edible oils, especially vegetable edible oils such as soybean oil and rapeseed oil. Vegetable edible oil is difficult to be thermally oxidized and is inexpensive, and at the same time, it does not ignite unless it reaches a high temperature of 320 ° C. or higher, so it is safe to heat to 100 ° C. to 230 ° C. In this case, as a safety measure, the oil heating means is controlled to automatically stop by a limiter at around 280 ° C. Even if edible oil leaks to the outside, it circulates in a low-pressure state rather than a high-pressure state like high-temperature steam, so it does not lead to soil contamination or serious accidents due to leakage. As mentioned above, soybean oil and rapeseed oil, which are inexpensive and difficult to be thermally oxidized, are suitable as the type of edible oil used in the present invention, but in addition to this, edible oil that is odorless and has a high ignition point and boiling point is used. preferable. Examples include sesame oil, salad oil, corn oil, cottonseed oil, safflower oil, peanut oil, and olive oil.

  The present invention heats and disinfects soil at a high temperature of 90 ° C. or higher using a heat pipe through which cooking oil at 100 ° C. to 230 ° C. passes. As a result, pathogenic bacteria, viruses and pests in the soil are almost killed, and soil disinfection can be performed safely in a short time. When the soil reaches 90 ° C or higher, the temperature of the oil is maintained at room temperature or higher even if the oil circulation is stopped after 1 hour or more, so that the oil can be immediately heated to 100 ° C to 230 ° C. Again, it can be easily circulated and used.

  In the apparatus of the present invention, operations such as oil temperature setting and circulation switching are all performed by automatic control. For this reason, no license or qualification is required for handling in driving operation without requiring human resources, and any farmer can easily introduce the apparatus of the present invention. For farmers, there is no need to install a large greenhouse in the soil or to apply high-pressure hot water, preventing soil contamination for a long period of time, and taking time from planting to harvesting. Significantly less. The heat pipe according to the present invention embeds approximately 300 pipes in parallel in a certain area unit of farmland, generally per one piece (300 tsubo) to form a sealed piping system.

  Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings. FIG. 1 is a block diagram conceptually illustrating a soil disinfecting apparatus according to the present invention, and FIG. 2 is a cross-sectional view showing a state where a heat pipe of the soil disinfecting apparatus is buried.

  In FIG. 1, 1 is a fryer as a heating means. The fryer 1 heats the cooking oil 2 which is a heat medium to 100 to 230 ° C. The operation of the fryer 1 is automatically controlled according to a predetermined program. As the edible oil 2, vegetable edible oils such as soybean oil and rapeseed oil which are difficult to be thermally oxidized and are inexpensive are used. The fryer 1 includes a sealed container 3 in which edible oil 2 is placed, and a combustion heater 4 that heats the container 3. The operation of the heater 4 is automatically stopped at about 280 ° C. by the operation of the limiter. One end of the heat medium outflow pipe 5 is attached to the side wall of the container 3, and one end of the heat medium inflow pipe 6 is attached to the center of the bottom of the container 3. One end of the forward pipe 7 is connected to the other end of the heat medium outlet pipe 5 by a connector 8 with a check valve, and a heat-resistant circulation pump 9 is provided in the middle of the forward pipe 7. On the other hand, one end of the return pipe 10 is connected to the other end of the heat medium inflow pipe 6 by a connector 11 with a check valve.

  Between the forward pipe 7 and the backward pipe 10, a heat medium pipe 19 having a loop shape is provided, and the pipe 19 is embedded in the soil of farmland to be sterilized. The configuration of the piping path 19 includes an outward path straight pipe section 14, a return path straight pipe section 15, and a pipe curve section 16 therebetween. The forward pipe 7 and the forward pipe straight portion 14 are connected to each other by a connector 17 with a check valve, and the return pipe 10 and the backward pipe straight portion 15 are connected to each other by a connector 18 with a check valve. Further, both ends of the pipe curve portion 16 are connected to the outward pipe straight portion 14 and the return pipe straight portion 15 by connectors 21 and 22 with check valves, respectively. The number of the outgoing path side pipe straight portions 14 and the number of the return path side pipe straight portions 15 can be provided in parallel according to the size of the farmland. Normally, about 300 pipes per farmland are buried in parallel and a set of piping units is installed.

  Reference numeral 12 denotes a metal heat pipe as a heat dissipating pipe for sterilization and sterilization, which is disposed at a predetermined position of the pipe line 19. The heat medium flow path in the heat pipe 12 is configured by the forward-side pipe straight portion 14 and the return-side pipe straight portion 15. As the heat medium, vegetable edible oil 2 such as soybean oil having a high boiling point is used. Even if the cooking oil 2 leaks into the soil, there is little damage and the specific heat is small, and it can be warmed quickly with little heat energy. As the heat pipe 12, a trade name “c-tube” (manufactured by Kajiura Co., Ltd.) that generates infrared electromagnetic waves and ultrasonic waves is used here.

  This pipe structure includes a mother pipe 12A whose inside is in a vacuum state, and a small edible oil distribution pipe, that is, an outward pipe straight portion 14 and a return pipe straight portion 15 are connected to the mother pipe 12A. Then, a working liquid (liquid having a low boiling point such as alcohol) 13 is enclosed in a state in which the pipe straight portions 14 and 15 are immersed while the inside of the mother pipe 12A is kept in a vacuum, and the heated cooking oil 2 is added to the pipe straight line. By circulating the parts 14 and 15, the hydraulic fluid 13 boils and becomes a jet (steam flow), and a large amount of heat is transferred to the surface of the mother pipe 12A at high speed. At the same time, it collides with the pipe wall at a speed close to the speed of sound of the jet in the pipe, whereby infrared electromagnetic waves and ultrasonic waves are radiated from the pipe surface together with direct heat. These rays give kinetic energy due to resonance absorption to water molecules having electrical polarity. This activates moisture in the plant body, enhances nutrient absorption, promotes detoxification and excretion, activates cell division, and promotes plant growth.

  Explaining the heat release mechanism in the soil of the heat pipe 12, the boiling point of the hydraulic fluid 13 further decreases in the vacuum of the mother pipe 12 </ b> A, the hydraulic fluid 13 boils from a low temperature region, and a vapor flow is generated from the liquid level boundary. To do. This steam flow accumulates latent heat from the heat source, travels toward the inner wall of the mother pipe 12A, and transports heat at a speed close to the speed of sound. The latent heat including the vapor flow is heat-exchanged with moisture in the soil on the inner wall of the mother pipe 12A, discharged outside the pipe, and condensed again into the liquid working liquid 13 to return. This evaporation-condensation cycle is continuously performed while heat is supplied, that is, while the heated edible oil 2 flows. The movement of the steam flow generates vibration with energy colliding with the inner wall of the mother pipe 12A. This vibration releases infrared electromagnetic waves and ultrasonic waves along with heat.

  As shown in FIG. 2, the heat pipe 12 is embedded in the eaves 23 and the side portions 24 thereof, and the depth of the embedding is set to about 300 mm from the ground surface. The soil to be sterilized by heating with the heat pipe 12 should appropriately contain at least 50% or more of moisture, and the higher the moisture content of the soil, the better the heating efficiency. This is thought to be because once the water in the evaporated soil reaches the heat retaining sheet 25 that covers the ground surface, it is liquefied again and returned to the soil, and is heated again to repeat evaporation. That is, the moisture in the soil is heated and circulated to improve the thermal efficiency. Therefore, it is desirable to cover the surface of the soil with a heat insulating sheet 25 having high heat insulation.

Next, the operation of this embodiment will be described.
In said structure, the cooking oil 2 in the container 3 of the fryer 1 is heated by the heater 4 at 100 to 230 degreeC. The heated edible oil 2 is sent from the heat medium outflow pipe 5 of the container 3 to the forward pipe straight portion 14 of the heat pipe 12 in a low pressure state by the circulation pump 9. Thereafter, the edible oil 2 sequentially flows through the pipe curve portion 16 and the return pipe straight portion 15 of the heat pipe 12, and returns to the container 3 of the fryer 1 again with the temperature lowered. The edible oil 2 returned to the container 3 is heated to 100 ° C. to 230 ° C. by the heater 4 and circulated and used again in the same manner as described above.

  The edible oil 2 at 100 ° C. to 230 ° C. passes through the heat pipe 12 in the soil (23, 24), so that the heat from the heat pipe 12 heats the soil from the ground surface to a depth of 500 mm to 90 ° C. or more. And safe soil disinfection becomes possible in a short time. That is, pathogenic bacteria and viruses that contaminate the soil are killed by heating at 90 ° C. or higher. After disinfection, it is possible to cultivate crops smoothly by supplying necessary microorganisms and fertilizers to the plant to be planted. This soil disinfection does not use any chemicals, increasing the commercial value of crops. In addition, continuous cultivation on farmland is possible, and environmental damage to the farmland and damage to the human body can be prevented.

  The edible oil 2 is heated to a temperature range of 100 ° C. to 230 ° C., and connectors 21 and 22 with check valves are used for connecting portions of the piping. Therefore, even when the heat pipe 12 is removed from the piping 19, there is no possibility that the edible oil 2 leaks, and deterioration of the oil due to oxidation reaction or overheating can be prevented. In addition, since the edible oil 2 does not ignite unless heated to at least 320 ° C. or higher, it is safe to heat the edible oil 2 to about 230 ° C. In the unlikely event that the temperature of the edible oil 2 abnormally rises to around 280 ° C., the operation of the fryer 1 is automatically stopped by the limiter, so that the edible oil 2 is not heated to 280 ° C. or higher. Even if the edible oil 2 leaks out of the heat pipe 12, the edible oil 2 is delivered at a low pressure, so that it does not spread over a wide area and may cause serious soil contamination and accidents. There is no. Furthermore, stop and activation of the fryer 1 and the circulation pump 9, and the temperature setting and circulation operation of the edible oil 2 are all automated. For this reason, no manual work is required, and the soil can be completely disinfected over a long period of time.

  In addition, this invention is not limited to the said Example, A various application deformation | transformation is possible. For example, in the above embodiment, when installing in a cold district or when the piping 19 is long, a plurality of fryer 1 may be provided in the middle of the piping 19.

  The soil disinfecting apparatus of the present invention can be widely applied to soils of general agricultural land other than greenhouse soils, and can obtain a high sterilizing and disinfecting action over a long period of time.

It is a block diagram which illustrates notionally the soil disinfection apparatus which concerns on this invention. It is sectional drawing which shows the embedding state of the heat pipe of a soil disinfection apparatus.

Explanation of symbols

1 Flyer (heating means)
2 Vegetable cooking oil (heat medium)
3 Sealed container 4 Heater (heating source)
5 Heat medium outflow pipe 6 Heat medium inflow pipe 7 Outward pipe 8 Connector with check valve 9 Heat-resistant circulation pump 10 Return pipe 11 Connector with check valve 12 Heat pipe (radiation pipe for soil high temperature disinfection)
12A Mother pipe 13 Hydraulic fluid 14 Outward pipe straight section 15 Return pipe straight section 16 Pipe curved section 17 Connector with check valve 18 Connector with check valve 19 Heat medium piping path 21 Connector with check valve 22 Check valve With connector 23 畝 24 Side 25 Thermal insulation sheet

Claims (1)

A soil disinfecting apparatus characterized in that a heat pipe in which a heat medium circulates is embedded in soil, a heating means for heating the heat medium to 100 ° C to 230 ° C is provided, and edible oil is used as the heat medium.

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