A boiler for producing hot water or steam, comprising a containment enclosure, which forms a heating chamber that contains water to be heated, and accommodating a firebox body, which forms internally a combustion chamber with a burner associated therewith which has a combustion head, accommodated in the combustion chamber, and a device for premixing air and gas which is connected to the combustion head. According to the invention, the premixing device comprises an air supply duct, which is connected to the combustion head, and a mixing tubular body, which is extended coaxially to the supply duct in order to create, between the internal lateral wall of the supply duct and the external surface of the sidewall of the mixing tubular body, an intake region which has a transverse air passage section that is narrower than the air passage section formed by the supply duct upstream of the mixing tubular body, along the air flow direction.

A boiler for producing hot water or steam, comprising a containment enclosure, which forms a heating chamber that contains water to be heated, and accommodating a firebox body, which forms internally a combustion chamber with a burner associated therewith which has a combustion head, accommodated in the combustion chamber, and a device for premixing air and gas which is connected to the combustion head. According to the invention, the premixing device comprises an air supply duct, which is connected to the combustion head, and a mixing tubular body, which is extended coaxially to the supply duct in order to create, between the internal lateral wall of the supply duct and the external surface of the sidewall of the mixing tubular body, an intake region which has a transverse air passage section that is narrower than the air passage section formed by the supply duct upstream of the mixing tubular body, along the air flow direction.

An expander of the piston (2) and cylinder (3) type is inverted from normal orientation, with the crankshaft (4) upper most and the cylinder head (5) lower most. The cylinder head has a pair of liquid injectors (6, 7) oriented for respective liquids pentane and glycerine to be injected as mists into contact with each other at the bottom of the cylinder. The pentane is vaporised by transfer of latent heat to it from the glycerine. Respective injector valves (9,10) from high pressure rails (11,12) fed by pumps (14,15) are provided. An exhaust valve (16) is opened by a cam (17) driven at crankshaft speed by a chain drive.

An expander of the piston (2) and cylinder (3) type is inverted from normal orientation, with the crankshaft (4) upper most and the cylinder head (5) lower most. The cylinder head has a pair of liquid injectors (6, 7) oriented for respective liquids pentane and glycerine to be injected as mists into contact with each other at the bottom of the cylinder. The pentane is vaporised by transfer of latent heat to it from the glycerine. Respective injector valves (9,10) from high pressure rails (11,12) fed by pumps (14,15) are provided. An exhaust valve (16) is opened by a cam (17) driven at crankshaft speed by a chain drive.

Waste heat is extracted in two stages from the exhaust (20) of a biomass dryer (14) in a grain alcohol plant (10). A boiler circuit (56) provides high pressure steam to a balance of the plant (54). A first energy recovery circuit (36) extracts heat from the exhaust via a non-contact heat exchanger (24) and provides a first relatively lower pressure steam (78) to the balance of the plant, thereby bypassing a portion of the boiler circuit. Working fluids in the boiler and first energy recovery circuits are maintained within boiler water quality specifications and are intermixed to allow the production of the first relatively lower pressure steam without a pressure reduction device. A second energy recovery circuit (44) extracts heat from the exhaust downstream of the first energy recovery circuit using a direct contact heat exchanger (38) and provides a non-boiler quality heated fluid (52) to the balance of the plant.

Waste heat is extracted in two stages from the exhaust (20) of a biomass dryer (14) in a grain alcohol plant (10). A boiler circuit (56) provides high pressure steam to a balance of the plant (54). A first energy recovery circuit (36) extracts heat from the exhaust via a non-contact heat exchanger (24) and provides a first relatively lower pressure steam (78) to the balance of the plant, thereby bypassing a portion of the boiler circuit. Working fluids in the boiler and first energy recovery circuits are maintained within boiler water quality specifications and are intermixed to allow the production of the first relatively lower pressure steam without a pressure reduction device. A second energy recovery circuit (44) extracts heat from the exhaust downstream of the first energy recovery circuit using a direct contact heat exchanger (38) and provides a non-boiler quality heated fluid (52) to the balance of the plant.

An arrangement includes a steam saturator for producing saturated steam and a device for refeeding the liquid evaporated in the steam saturator. The steam saturator includes a steam inlet via which steam is delivered to the steam saturator, a steam outlet for the saturated steam produced, a condensate inlet via which condensate is delivered to the steam saturator, and a condensate return line. In a lower region of the steam saturator, a condensate liquid level that is fluidically connected to the condensate return line is maintained. The condensate return line is connected to the device, which is a condenser and comprises a cooling apparatus for condensing steam. In the steam saturator, the evaporated liquid is replaced only if the condensate level in the steam saturator drops, through condensation of saturated steam delivered from the steam saturator to the condenser and is then condensed in the condenser by the cooling apparatus.

An arrangement includes a steam saturator for producing saturated steam and a device for refeeding the liquid evaporated in the steam saturator. The steam saturator includes a steam inlet via which steam is delivered to the steam saturator, a steam outlet for the saturated steam produced, a condensate inlet via which condensate is delivered to the steam saturator, and a condensate return line. In a lower region of the steam saturator, a condensate liquid level that is fluidically connected to the condensate return line is maintained. The condensate return line is connected to the device, which is a condenser and comprises a cooling apparatus for condensing steam. In the steam saturator, the evaporated liquid is replaced only if the condensate level in the steam saturator drops, through condensation of saturated steam delivered from the steam saturator to the condenser and is then condensed in the condenser by the cooling apparatus.