FR2777069A1 - Natural gas or LPG air heater for preventing frost around crops - Google Patents

Abstract

The air heater is composed of a gas source (9), a gas pressure regulator (10) and a network of pipes (11,12) for distributing the gas to burners (13). The burners use oxygen from the ambient air for the combustion of the fuel and the burners are operated by a pilot light.

Description

The present invention relates to an ambient air heating device

  around freezing cultures. Oil heating devices commonly known as burners or heaters have been known for a long time to protect frost crops such as vines or fruit trees. The burners conventionally comprise a tank, a cover above the tank, a chimney surmounting the tank and a burner head capable of heating the closed space delimited by the tank and the cover and part of the internal space of the chimney. . The burners crisscross the ground and are connected to each other by O oil lines connected to a pumping station and to an oil tank. These devices protect frost crops but the incomplete combustion of fuel oil causes significant air pollution and leaks or ruptured pipes spread fuel oil on the soil. The device according to the invention overcomes this drawback. In fact, it uses either natural gas (rich in methane) or a liquefied petroleum gas called LPG (Butane, Propane, etc.). The device consists of a source of gas (natural gas or LPG); gas pressure regulation, a pipeline network for distributing the gas to the burners; gas burners; pilot light for ignition on demand. 2 Natural gas arrives either through the distributor's piping network (GDF), or by cryogenic storage located near the crops to be protected. A cryogenic tank pressure regulator and an atmospheric evaporator provide methane gas in sufficient quantity for use at a few bar of pressure. The LPG is stored in tanks in the liquid state. The specific consumption2 of LPG in the gaseous phase requires a heating vaporizer to compensate for the latent heat of vaporization at the outlet of the storage. The use of the gas burner in

  Liquid LPG does not require a vaporizer After the gas source, the network is connected to a regulator. The regulator regulates the pressure of the gas from the piping network connected to the gas burners. The higher or lower pressure setting will determine the gas flow through the burners and therefore the power of the burners.

  Gas burners are designed to burn with the oxygen contained in the ambient air. The burner consists of a cylindrical tube with a flat bottom pierced to receive the injector and to let the air sucked in pass by the speed of the gas. The device provides a start of combustion in the cylinder with a turbulent flame. The diameter of the injector passage characterizes the power of the burner. The height of the cylinder is 2.5 times its diameter. The drilling of the flat bottom and the injector is specific to the gas used. The air inlets can be drilled on the cylinder and not on the dish. The injector and the air inlets can be placed upstream of the cylinder. The gas burner flame can be positioned vertically above the ground, or horizontally or at an intermediate position. A simple burner support makes it possible to position the orientation of the flame. This support can be dissociated from the burner to allow the installation to be removed without dissociating the burners from the secondary network. The combustion energy can be transmitted to a material (steel, ...)

  so that it partially transforms it into radiation energy.

  At very low pressure, the gas burner generates a flame of very low intensity called the pilot flame. The burner is lit on a standby before the cold arrives. The pilot state consumes very little gas and instantly allows the burners to start up by increasing the pressure on the pipeline network. A second gas network can power a pilot positioned near

1 0 from the main burner.

  The accompanying drawings, given solely by way of example, illustrate the invention: FIG. 1 represents the diagram of a process comprising the gas source, the pressure regulation, the pipe network and the gas burners; Figure 2 shows in section a gas burner;

  i 5 Figure 3 shows in section a gas burner and its support for vertical flame.

  With reference to these drawings, the device for protecting gelling cultures according to the invention comprises a source of propane gas equipped with a reservoir and a heating vaporizer (9); this gas source is equipped with all the safety devices in accordance with the regulations in force; this gas source feeds a regulator (10) which regulates the pressure downstream from 0 to 2 Bar; the diameter of the regulator seat is sized according to the desired flow rates and pressures, this diameter can be 20 mm for a balanced valve with closure in low pressure; at the outlet of the regulator (10), we have the piping network which can be a 50 mm inside pipe; this piping supplies a secondary network (12) of pipe with an inside diameter of 8 min which supplies the burners (13) with gas; the gas burners (13) are characterized by an inlet pipe (3) for combustible gas, a nozzle (14) and a cylinder (1) from which the flame comes out; the support is designed in such a way that the burner can be positioned after it has been connected to the gas network; for this 2 angles (7) are opposite and adjusted to match the cylinder 3 (0) of the burner (13); a stop (6) placed opposite the gas pipe (3) positions the cylinder in height at its flat bottom (2); the burners (13) are connected to the secondary network (12) by a 40 cm brass tube (3); the injectors (14) are drilled at 10/10 and the flat bottom (2) of the burner is drilled with 4 holes of diameter 10 min (4) to allow the passage of air (15) for the primary mixture; at very low pressure, the burners (13) are lit: they operate in the pilot; it suffices to increase the pressure setpoint of the regulator (10) to increase the power of the burners (13) to combat the risk of freezing of crops such as vines or fruit trees. This device may be supplemented by a temperature measuring device which will control, depending on the

4 0 set points, gas pressure.

Claims (9)

  1- Device for heating the ambient air around frost crops such as vines or fruit trees, using a source (9) of natural gas or LPG (liquid petroleum gas), regulating the flow of gas to the using pressure regulation (10) for a given section of nozzles (14), burners (13) supplied by a primary network (11) and a secondary network (12), characterized in that the gas burners   use as oxidant the oxygen naturally present in the air.   2- Device according to claim 1, characterized in that the gas flow at the outlet of the injectors (14) of the burner (13) drives the air (15) to constitute the air primary combustion.   3- Device according to claim 1 or 2, characterized in that the height of the cylinder (1), its dianmeter, the air inlets (4) and the diameter of the injectors (14)   are determined to obtain a start of combustion in the cylinder (l).   4- Device according to one of claims 1 to 3, characterized in that the flame is turbulent.   5- Device according to one of claims 1 to 4, characterized in that the power   of the burners is defined by the diameter of the injector passage (14) and the pressure gas in the manifold (3).   6- Device according to one of claims I to 5, characterized in that the burners   can operate on standby, with low gas consumption pending the temperature drop.   7- Device according to one of claims 1 to 6, characterized in that the arrivals   air (15) in the burner can be located on the bottom (2) of the cylinder (1) or on the   generator of the cylinder (1) or both.   8- Device according to claim 1, characterized in that the support (8) can be dissociated from the burner (13) to allow the removal of the installation without dissociating the   secondary network burners (13).   9- Device according to claim 1, characterized in that the cryogenic methane or liquefied petroleum gas can be drawn off in the liquid phase and then reheated by adding external calories for use in the gas phase in the   network supplying the regulator (10).