"CLOSED CIRCUIT CYCLE FOR COMBUSTION PRODUCTS" *=*=+=* The present invention relates to a closed-circuit cycle for combustion products, 4 useful for fuels in any physical state (solid, liquid or gas). It is applicable to all apparatus where combustion of solid, liquid or gaseous fuels is employed and in which the-combustion product is discharged by means of a flue, chimney or exhaust pipe and then released into the atmosphere.

This method, which is universally and widely used, creates major pollution problems.

In. particular, ~significant problems have recently been encountered in built-up areas, where the exhaust gases tend to accumulate, creating zones which, during certain hours, have a level of pollution notably higher than average.

The combustion process normally uses the oxygen contained in the mass of atmospheric air, but in so doing it is required to heat up the whole air mass, 4/5ths of which consist of so-called inert gases; said air mass is heated increasing the amount of used fuel and is discharged in its entirety into the atmosphere, resulting in pollution due to nitrogenous substances, oxidising substances, acid water, thermal heating, etc.

The object of the present invention is to eliminate from the combustion process the inert substances which are contained mainly in the atmosphere, recycling only a part thereof sufficient and necessary for absorbing the thermal and kinetic energy, and then releasing it for use.

This object is achieved by means of a closed-circuit cycle for combustion products, to be used in internal- combustion engines or plants, characterised in that the gas produced is not discharged directly into the atmosphere, but is recycled for combustion purposes. The oxygen needed to meet the combustion requirement will preferably be

supplied, preferably in the pure state, from a special tank which will be replenished in each case depending on the consumption required.

The potential advantages of the present invention are many: elimination of the nitrogenous substances from the exhaust gases, reduction in thermal heating of the atmosphere, reduction in the oxidising substances, etc. etc. , but the characteristic features will emerge more clearly from the description and from the schematic drawings which, by way of a non-limiting example, illustrate how all the abovementioned objects may be achieved and in which: Fig. 1 is a basic diagram which illustrates operation of the cycle according to the present invention; Fig. 2 is a diagram which illustrates application thereof to an internal-combustion engine; Fig. 3 is a diagram which illustrates application thereof to a steam boiler or to a furnace; and Fig. 4 is a diagram which illustrates application thereof to a gas turbine.

Fig. 1 shows in schematic form all the stages in the closed-circuit cycle. 1 denotes the fuel combustion stage inside the combustion chamber; 2 denotes the stage where the energy produced by combustion is used; 3 denotes the stage involving recovery and conveying of the return gases of the combustion product to the combustion chamber indicated by 1, so as to boost combustion further; 4 denotes discharging of the accumulated excess quantity of combustion product; 5 denotes introduction of the oxygen, which is substantially equal to the quantity present in the air mass of the atmosphere; 6 denotes introduction of the fuel inside the combustion chamber 1 in order to recreate the inflammable mixture. In this way the closed-circuit is repeatedly continuously.

Fig. 2 illustrates schematically an internal- combustion engine in which: 2 denotes the combustion or explosion chamber; 8 denotes the use of the energy produced by combustion; 9 denotes the exhaust manifold which returns to the intake manifold; 10 denotes discharging of the excess gas; 11 denotes the introduction of oxygen in order to recreate the inflammable mixture with the introduction of the fuel indicated by 12. All of this returns into the combustion chamber, perpetuating the cycle.

Fig. 3 schematically shows a steam boiler or a furnace of a generic plant. 13 denotes the combustion chamber; 14 the energy supplied to the user; 15 discharging of the combustion product conveyed by suitably designed mechanical means, with return recovery inside the combustion chamber and introduction of the oxygen at 16, so as to recreate the mixture with the comburent agent; 17 denotes discharging of the excess gas of the combustion product; 18 denotes the fresh fuel which is introduced into the combustion chamber.

Fig. 4 relates to a gas turbine; 19 denotes the combustion or reaction chamber; 20 denotes the turbine using the energy produced by combustion; 21 denotes discharging of the combustion product conveyed into a compression mechanism; 22 denotes discharging of the excess gas; 23 denotes introduction of the oxygen in order to recreate the mixture with the comburent agent; 24 denotes a mechanism for compression of the gas to be compressed inside the combustion chamber; 25 denotes the introduction of the fuel so as to form the combustion mixture. Thus the cycle is closed, continuing ad infinitum.

The present invention is particularly useful for internal-combustion vehicles since it avoids the discharging of uncombusted fuel into the atmosphere. For example, it is particularly useful when applied to buses operating on an urban route. It is even more useful if the

excess exhaust gas, instead of being discharged directly into the atmosphere, is conveyed to a storage device- which could be, for example, a gas cylinder-if necessary with the aid of a compressor. In this case, by providing the system with suitable filters, the accumulated COs may be used for industrial purposes or also alimentary purposes, avoiding the need to produce it especially, thereby limiting the increase in the greenhouse effect.

Alternatively, this gas may then be discharged into the atmosphere in a zone where there is less pollution, such as a zone which is not built-up.