Fishing – trapping – and vermin destroying – Vermin destroying – Fumigators
Reexamination Certificate
1999-05-25
2001-08-28
Ark, Darren W. (Department: 3643)
Fishing, trapping, and vermin destroying
Vermin destroying
Fumigators
C422S032000, C422S037000
Reexamination Certificate
active
06279261
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to the control of pests mainly in the protection of stored products or in food-processing plants by means of heat.
BACKGROUND OF THE INVENTION
Oil- or gas-heated burners have been used in Denmark for a rather long time for controlling
Hylotrupes bajulus
in roofs. Oil or gas is burned and the heat released in the process heats air, which is introduced with the combustion gases into the infested roof truss. After a correspondingly long exposure time, the pests in the rafters are dead. Similar processes are also used to control termites and cockroaches in the U.S.A. The buildings are wrapped in foils or tarpaulins at the same time in this process in order to keep the heat loss as low as possible. The wrapping of the buildings in tent foils is not possible or too expensive in the case of large objects, such as mills or large food-processing plants.
WO 92/00173 describes a process from the Netherlands, in which the heated air in the room being treated is additionally maintained at a minimum humidity level. The combustion gases are disadvantageously introduced into the room being treated; this process cannot be used in food-processing plants.
EP 0 416 255 A1 describes a process in which a mill, which is infested with pests, is freed from pests such that the inner walls are heated to a minimum temperature of about 27° C. before carbon dioxide is admitted. For heating, heating devices are set up in the room to be treated itself, and the carbon dioxide is heated as well.
A thermal disinfestation process, in which explosion-proof electric heaters set up in the room to be treated are used, is described in the article by H. Hofmeier, Pest Control with Heat in Mills, Bakeries and Restaurants,
Die Mühle+Mischfuttertechnik,
Vol. 133, Nos. 51/52, Dec. 19, 1996, pp. 842 ff. The energy consumption is very high due to the relatively low efficiency of the electric heater, and mills with large room space can be heated up for pest control only if a block-type thermal power station is additionally available.
Electric heaters for pest control in mills, etc., are also described in the utility model DE 29618646 U1.
The article by J. A. Teich, Thermal Pest Control in Mills,
Die Mühle+Mischfuttertechnik,
Vol. 133, No. 11, Mar. 14, 1996, pp. 172 ff., describes a process in which hot steam is used for disinfection in mills. However, the hot steam may precipitate on cooler parts and damage due to moisture may thus occur in the mill. In addition, molds will increasingly grow after the heat treatment because of the increased moisture content present in the mill after the treatment.
Combinations of heat with carbon dioxide, phosphine and dichlorvos have become known from the U.S.A. U.S. Pat. No. 5,403,597 describes a combined process comprising heat from steam, natural gas and electricity, carbon dioxide and phosphine. Electric heaters are used predominantly. The electric heaters consume a very large amount of energy, and they are therefore sometimes replaced with gas-heated furnaces. These are operated until shortly before the admission of carbon dioxide and phosphine and are then switched off, because phosphine would decompose in the gas-heated burner. The consequence would be even more intense corrosion phenomena than those induced by phosphine itself. In addition, this process has the drawback that the room to be treated cools more or less rapidly during the gas exposure time after the gas-heated burners have been switched off (Fumigation and Pheromones Workshop, West Lafayette, Ind., U.S.A., 1996, with practical demonstration of the process by D. and J. Mueller). This leads to a loss of effectiveness during the process, because the pests breath in the phosphine substantially more rapidly at higher temperatures.
Problems also occur in the case of the use of carbon dioxide as a fumigant with the simultaneous heating of the atmosphere in the room being treated by means of oil- or gas-heated burners. Flue gases, which may contaminate the food remnants or foods proper in the room being treated, are generated by the combustion process. In particular, fuel oil contains sulfur compounds, which can be found in the form of sulfate or sulfite in food remnants in the mill. An overpressure is also generated in the room being treated due to the combustion process, because additional gases are introduced into the room being treated, so that the sealing needed for the fumigation may be damaged and greater losses of gas or heat may occur.
SUMMARY AND OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a process in which thermal pest control can be carried out in mills or other food-processing plants or food warehouses economically and effectively, and these processes may optionally also be employed combined with fumigation processes without, e.g., increased losses of gas or temperature drops occurring during the treatment.
According to the invention, a process is provided for the disinfestation of mills, food-processing plants or other pest-infested rooms with hot air by introducing hot air into the room to be treated by means of a fuel-heated heater. The heater has a separate flue gas routing, as a result of which no flue gases will enter the room being treated. The heater has a combustion chamber, which is separated by a heat exchanger from a heat exchanger chamber. The air to be heated is removed from the room being treated through the heat exchanger chamber continuously or intermittently, heated and returned into the room being treated. The combustion chamber is separated from the heat exchanger chamber in a gas-tight manner. Sulfuryl fluoride is introduced as a fumigant into the room being treated before, during or after the heating of the air of the room being treated.
As in the state of the art, e.g., oil- or gas-heated burners or combustion chambers heated with other fuels are used in the process according to the present invention. The air in the room to be treated is heated via heat exchanger surfaces. The atmosphere of the room being treated is separated from the burner space of the heater in a gas-tight manner in the process according to the present invention, and the heater is preferably located outside the room to be treated. This offers the advantage that the air of the room to be treated is not contaminated with flue gases, because these are removed from the combustion chamber, e.g., into the environment.
Since the air of the room to be treated, which air is to be heated, does not come into contact with open flames or red hot parts or particles, the process is also suitable for heating mills without flour dust explosions occurring.
In the preferred embodiment of the present invention, part of the atmosphere of the treated room, which atmosphere is to be heated, is passed continuously or intermittently or in a controllable manner through the heat exchanger chamber of the heater, heated in the process, and returned into the room to be treated. A circulation is generated as a result, and the heat is thus distributed uniformly in the room being treated. The distribution of the heat in the room being treated may be brought about additionally by means of pipe distributions in the room being treated, so that high temperatures desirable for killing the insects can be reached even in areas in which the temperatures are sometimes low. Due to the gas-tight separation of the heat exchanger chamber from the combustion chamber and the gas-tight routing of the pipes, gases can be additionally introduced into the heat circulation. The fumigants additionally introduced into the room to be treated, which are then distributed uniformly in the room being treated due to the circulation by means of the heater or heaters, ensure an even more rapid killing of the insects. The fumigants are particularly effective due to the increase in temperature, because the insects breath more or less rapidly depending on the ambient temperature and thus they rapidly incorporate the fumigants and are killed more rapidly. The fumigants are prefer
Binker Gerhard
Binker Joachim
Ark Darren W.
Binker Materialschutz GmbH
McGlew & Tutle, P.C.
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