Method of supplying thermal energy to the heater of a hot-gas engine, as well as a hot-gas engine comprising a device for carrying out the method

Claim 2

In a hot gas engine including a housing, a burner for combustion of air and fuel producing combustion gases and a heater comprising a plurality of ducts for exchange of heat from said combustion gases to fluid medium flowing in said ducts, the improvement in combination therewith wherein said heater ducts are situated within said housing and define a first annular space surrounded by the ducts, a second annular space surrounding the ducts, and a third space axially adjacent said ducts, said first and third spaces comprising a primary combustion space, said second space comprising a secondary combustion space including a discharge outlet, said apparatus further comprising means for supplying to said primary combustion space fuel and a quantity of air which is stoichiometrically insufficient for complete combustion of the supplied fuel resulting in combustion at a temperature lower than the temperature of stoichiometric combustion, the apparatus further comprising secondary means for supplying air to said secondary combustion space for reaction with combustion gases that flow there from the primary combustion space, said heater ducts absorbing heat from and reducing the temperature of said combustion gas which flows past the ducts from the primary to secondary combustion spaces, said heat removal in combination with non-stoichiometric combustion ensuring that the temperature of said combustion gases remain below the corresponding stoichiometric temperature such that formation of nitrogen oxides is inhibited.

Claim 3

Apparatus according to claim 1 wherein said secondary combustion space is dimensioned to be sufficiently large relative to the quantity of combustion gas therein, such that combustion reactions in this secondary combustion space reach substantial chemical equilibrium generally adiabatically before exiting this space.

Claim 4

Apparatus according to claim 1 further comprising catalyst means situated in said primary combustion chamber in the proximity of said heater parts for stimulating ignition and combustion of said gas mixture.

Claim 5

Apparatus according to claim 1 wherein said primary combustion chamber has walls and wherein said catalyst means is situated in the proximity of certain of said walls.

Claim 6

Apparatus according to claim 1 wherein said catalyst means comprises finely divided platinum.

Claim 7

Apparatus according to claim 1 wherein said heater ducts comprise first and second parts, said first part being in the flow path of combustion gases from said primary to said secondary combustion chambers, said second part being in the flow path of combustion gases from said second combustion chamber to said outlet therefrom.

Claim 8

In a combustion engine including a housing, a burner for combustion of air and fuel producing combustion gases and a heater comprising a plurality of ducts for exchange of heat from said combustion gases to fluid medium flowing in said ducts, the improvement in combination therewith wherein said heater ducts are situated within said housing and define a first annular space surrounded by the ducts, a second annular space surrounding the ducts, and a third space axially adjacent said ducts, said first and third spaces comprising a primary combustion space, said second space comprising a secondary combustion space including a discharge outlet, said apparatus further comprising means for supplying to said primary combustion space fuel and a quantity of air which is stoichiometrically insufficient for complete combustion of the supplied fuel resulting in combustion at a temperature lower than the temperature of stoichiometric combustion, the apparatus further comprising secondary means for supplying air to said secondary combustion space for reaction with combustion gases that flow there from the primary combustion space, said heater ducts absorbing heat from and reducing the temperature of said combustion gas which flows past the ducts from the primary to secondary combustion spaces, said heat removal in combination with non-stoichiometric combustion ensuring that the temperature of said combustion gases remain below the corresponding stoichiometric temperature such that formation of nitrogen oxides is inhibited.

Claim 9

In a combustion engine including a housing, a burner for combustion of air and fuel producing combustion gases and a heater comprising a plurality of ducts for exchange of heat from said combustion gases to fluid medium flowing in said ducts, the improvement in combination therewith wherein said heater ducts are situated within said housing and define a first annular space surrounded by the ducts, a second annular space surrounding the ducts, and a third space axially adjacent said ducts, said first and third spaces comprising a primary combustion space, said second space comprising a secondary combustion space including a discharge outlet, said apparatus further comprising means for supplying to said primary combustion space fuel and a quantity of air which is stoichiometrically insufficient for complete combustion of the supplied fuel resulting in combustion at a temperature lower than the temperature of stoichiometric combustion, the apparatus further comprising secondary means for supplying air to said secondary combustion space for reaction with combustion gases that flow there from the primary combustion space, said heater ducts absorbing heat from and reducing the temperature of said combustion gas which flows past the ducts from the primary to secondary combustion spaces, said heat removal in combination with non-stoichiometric combustion ensuring that the temperature of said combustion gases remain below the corresponding stoichiometric temperature such that formation of nitrogen oxides is inhibited.

Claim 10

In a method of supplying thermal energy to the heater of a hot gas engine which engine includes a burner in a primary combustion chamber for combustion of fuel and air and heater ducts for exchanging thermal energy from combustion gas to fluid medium flowing in said ducts, the improvement in combination therewith comprising the steps: supplying to said burner a quantity of fuel, supplying to said burner a quantity of air which is stoichiometrically insufficient for complete combustion of the supplied fuel, igniting and burning said fuel and air in incomplete combustion forming combustion gases at a temperature lower than the temperature of combustion gases formed in stoichiometric combustion, flowing said combustion gases past and in contact with said ducts for transferring thermal energy from said gases to said fluid flowing within said ducts and thereby reducing the temperature of said gases, and thence flowing said gases into a secondary combustion chamber for continuing oxidation thereof, supplying to said secondary combustion chamber air in quantity sufficient for complete combustion of said gases therein, providing said second combustion chamber with volume sufficiently large to allow the expansion of said combustion gas therein to reach chemical equilibrium substantially adiabatiacally, and flowing said products of combustion in said secondary chamber past and in contact with said heater ducts for further transferring thermal energy thereto.

Claim 11

In a method of supplying thermal energy to the heater of a hot gas engine which engine includes a burner in a primary combustion chamber for combustion of fuel and air and heater ducts for exchanging thermal energy from combustion gas to fluid medium flowing in said ducts, the improvement in combination therewith comprising the steps: supplying to said burner a quantity of fuel, supplying to said burner a quantity of air which is stoichiometrically insufficient for complete combustion of the supplied fuel, igniting and burning said fuel and air in incomplete combustion forming combustion gases at a temperature lower than the temperature of combustion gases formed in stoichiometric combustion, flowing said combustion gases past and in contact with said ducts for transferring thermal energy from said gases to said fluid flowing within said ducts and thereby reducing the temperature of said gases, and thence flowing said gases into a secondary combustion chamber for continuing oxidation thereof, supplying to said secondary combustion chamber air in quantity sufficient for complete combustion of said gases therein, providing said second combustion chamber with volume sufficiently large to allow the expansion of said combustion gas therein to reach chemical equilibrium substantially adiabatiacally, and flowing said products of combustion in said secondary chamber past and in contact with said heater ducts for further transferring thermal energy thereto.

Claim 12

A method according to claim 8 comprising the further step of providing catalyst means in said primary combustion chamber and thereby stimulating ignition and combustion of said gas and air.