The present invention relates to equipment for utilizing biofuel as fuel. It is obvious that an ordinary boiler for a private home can be fired by oil, coke, wood or electricity. It is thus also fairly obvious to use biofuel instead of coke or wood, thereby obtaining energy for heating a boiler supplying water-borne heat and hot water in a property. The most convenient method of arranging heating of a property is to use oil, the oil being combusted intermittently which means that the heating costs can be kept to a minimum. The use of oil firing is extremely convenient. The same is true of heating by means of electricity. It would be extremely convenient also to be able to use biofuel in a manner enabling the same degree of convenience as with the use of oil. However, heating with biofuel requires more manual assistance and biofuel is therefore more laborious. The object of the present invention is to provide equipment for biofuel which functions in substantially the same way as equipment using oil. From a purely practical point of view this is achieved by shaping the biofuel into units of the same type. A suitable shape for such units is pellet-shape. Said units are supplied to a combustion unit where the units are gasified and the gas produced is supplied intermittently to a combustion chamber. The gas supplied is ignited, whereupon the energy produced at combustion of the gas can be used for other purposes, such as for heating the water in a boiler or other suitable purposes, e.g. generating electricity. The actual gasification occurs at an operating temperature in the order of magnitude of 1000°C and also under a certain positive pressure. This means that the fuel units must pass a number of sluices which must be heat-resistant and sealed so that the gas produced does not leak out. A sluice may consist of a transversely movable gate and a rotatable body which can assume two different positions and which is provided with a passage to be brought into and out of alignment with the feed-down passage to t he gasification unit.

The gasification unit is also provided with a feed-out unit which, taking into consideration operating temperature and positive pressure,

is provided with one or more sluices of the same type as the fuel feed- in unit.

A sluice connects the gasification unit to a combustion chamber, preferably closed, but suitably with valves for pressure equalization.

A control unit is used for the gasification unit and for any sluices, so that combustion in the equipment is controlled in a predetermined manner, preferably intermittently.

The gasification unit suitably runs on electricity.

The gasification chamber may suitably be placed in the fuel space in a conventional boiler, thereby effecting intermittent heating of the boiler in the same way as if the fuel had been oil.

Additional characteristics of the present invention are revealed in the appended claims.

The present invention will be described in more detail with reference to the accompany nine drawings in which

Figures 1 and 2 together show a complete equipment for biofuel and where Figures 3-9 show the equipment at different stages of operation.

Figure 1 shows a fuel container for spherical pellets of uniform size. These pellets have been designated 2. Such pellets are most suitably produced by baling together various types of organic substances. The substances may be residue from felling trees, straw, hay, waste from building sites, shavings from sawmills, etc. When said fuel is ground it can easily be formed into cylindrical pellets. During the grinding organic matter is also added so that the spherical bodies formed are stable and relatively hard, thereby remaining in tact during transport. The intention is that such spherical pellets shall be transferred by tanker from their place of manufacture to where they are to be used, such as a fuel depot 1. Said tanker is imagined provided with a hose

through which the pellets are supplied to the fuel depot. It should be obvious that during transport of the pellets from the transport vehicle to the fuel depot, air can be used so that, substantially, a fluidized bed is produced. A fuel feed-in unit 3 is arranged connected to the fuel depot, this fuel unit containing means for transporting one pellet at a time to a gasification unit 4. The gasification unit 4 is designed to run on electricity and in such a manner that a pellet 2 supplied is gasified. The gas produced can be supplied to a combustion chamber 6 in a boiler filled with water. Said boiler may be considered as a heat-recovery unit and is designated 7. Cold water is supplied to the heat- recovery unit via a pipe 8. Said water leaves the heat-recovery unit via a pipe 9 in the form of hot water. The gasification unit 4 is connected to a feed-out unit 5, so designed that ash formed is supplied to a container 22 for collecting ash.

The fuel feed-in unit 3 is provided with three gates 1, sliding transversely and intended to allow one pellet through at a time. Said pellet is then carried further by a sluice 12 having a movable part in the form of a cylinder or sphere with a passage which can be brought into alignment with the passage from the fuel container 10. Said passage can thus assume two different positions. Following said sluice is a second sluice 14, identical to the sluice 12. Finally, the fuel feed-in unit has a second gate 15 of the same type as the gate 11. The gasification unit 4 includes a gas-generating furnace 17, preferably of electric type and capable of emitting a temperature in the order of magnitude of 1000°C and thus also creating a certain positive pressure. The furnace 17 is in communication with a gas valve 16 communicating with the combustion chamber 6.

The feed-out unit 5 includes means for transporting any ash produced in the gas-generating furnace 17 to a container 22 for collecting ash. Between the furnace and the ash container 22 is a transverse gate 18 and two sluices 19 and 21. All these three units are of the same type as the units in the fuel feed-in unit 3.

The units 11, 12, 14, 18, 19 and 21 must be of a type that will withstand high temperatures and also prevent gas leakage from the furnace 17.

The combustion chamber 6 which is closed, is provided at each end with two valves 13 and 20, respectively, for pressure equalization. These two valves may be of the same type as the sluices 12, 14, 19 and 21.

All adjustable units in the equipment and the gas-generating furnace are controlled by a control unit 3 and this control may be chosen in a manner known per se depending on how the equipment is to function.

As to the choice of temperatures in the equipment, it is important that the ash supplied to the ash container 22 shall be in powder form.

The described equipment functions are described in the following. It is advisable to consider Figure 3 which clearly shows that a pellet 2 has left the fuel container 10 and that the gate prevents a second pellet from following the first one. When this has occurred the sluice 12 is set so that its passage coincides with the passage through the equipment so that the pellet 2 arrives at the sluice 14. This is aligned as shown in Figure 5 so that the pellet 2 arrives at the gate 15. When the gate 15 has opened the pellet arrives in the furnace 17 and is fully gasified so that a positive pressure occurs at the same time as the gas obtains high temperature. The gas produced may not disappear either upwards or downwards and the various units must therefore be tight, both above and below, and must also withstand the temperature prevailing in the furnace. When, for instance the heat-recovery unit 7 requires more heat, the valve 16 will be opened and gas is obtained which is spontaneously combusted and which provides the desired energy. When this has occurred, the valve 16 is again in closed position.

Another pellet 2 is fed down into the equipment when more gas is needed in the gas-generating furnace 17.

It should be clear that, if desired, the pellets can be made smaller so that the gate 11 allows through a predetermined number of pellets.

It is evident from the above that equipment has been created that utilizes pellets in such a way that the equipment functions intermittently with a boiler just as any other known oil-fired equipment. Equipment has thus been produced which is just as efficient as oil-fired equipment but which is extremely environment- friendly.