A shell-and-tube heat exchanger comprises a shell enclosing a plurality of U-shaped tubes. Each tube is provided with a first portion and with a second portion. The open ends of each tube are connected to a tube-sheet. A pressure chamber is connected to the tube-sheet. The pressure chamber contains a guiding jacket that, at a first end thereof, is sealingly joined to the tube-sheet or the first tube portions and, at a second end thereof that is opposite to the first end, is open. The guiding jacket splits the pressure chamber into a first section and a second section. The first section and the second section are in communication with each other by means of the open end of the guiding jacket. The first section is provided with a liquid level, located below the open end, and therefore with a vapour chamber, located above the liquid level.

A novel two-chamber design for thermal boilers is presented in this document. The boiler uses spiral-shaped tubes with conical and flat portions which form a combustion chamber. The use of a direct flame burner causes exhaust gas turbulence and increases the gas pressure in the main chamber. The high-pressure gases, which have lost their kinetic energy due to collision with spirals, leave the main chamber and enter into the secondary chamber, where their energy is used to preheat inlet water. The control of distance between spirals, the reverse flow of exhaust gases in the chambers, and the specific geometry of the spirals maximize boiler efficiency,

A vaporizer apparatus for vaporizing liquefied natural gas (LNG) into vapor-phase natural gas for injection into an oil or gas well, comprises a blower assembly, a burner section, a heat exchanger section, and at least one flammable gas concentration sensor. The blower assembly comprises a primary blower configured to move air along an air flow path through the vaporizer apparatus and a flame arrestor configured to allow passage of the air into the vaporizer apparatus and impede passage of a flame out of the vaporizer apparatus. The burner section comprises an enclosure having an upstream end coupled to the blower assembly and a downstream end, and a burner inside the enclosure and in the air flow path for heating the air. The heat exchanger section comprises an enclosure having an upstream end coupled to the downstream end of the burner section enclosure and a downstream end, and at least one LNG heat exchange tube inside the enclosure and in the air flow path, and thermally communicable with the air heated by the burner. The at least one flammable gas concentration sensor is in the air flow path upstream of the burner and is configured to detect whether a concentration of a flammable gas in the air is above a flammable gas concentration set point.

A novel two-chamber design for thermal boilers is presented in this document. The boiler uses spiral-shaped tubes with conical and flat portions which form a combustion chamber. The use of a direct flame burner causes exhaust gas turbulence and increases the gas pressure in the main chamber. The high-pressure gases, which have lost their kinetic energy due to collision with spirals, leave the main chamber and enter into the secondary chamber, where their energy is used to preheat inlet water. The control of distance between spirals, the reverse flow of exhaust gases in the chambers, and the specific geometry of the spirals maximize boiler efficiency,

A waste heat boiler has heat exchange tubes for indirect heat exchange of a relatively hot process gas and a cooling media, and a by-pass tube for by-passing a part of the process gas; a swirl mixer ensures mixing of the cooled process gas and the relative hot process gas exiting the heat exchange tubes and the by-pass tube.

A method for improving the efficiency of a fired heater without an air preheat system is described. The method involves the use of an additional outboard convection section which is separate from the regular convection section of the fired heater. The outboard convection section uses the boiler feed water or an alternate cold sink to reduce the temperature of the flue gas, thereby improving the efficiency.

A method for improving the efficiency of a fired heater without an air preheat system is described. The method involves the use of an additional outboard convection section which is separate from the regular convection section of the fired heater. The outboard convection section uses the boiler feed water or an alternate cold sink to reduce the temperature of the flue gas, thereby improving the efficiency.

A shell-and-tube apparatus (1), suitable for use as a waste heat boiler, comprising a vessel with an exchanging section (2) and a separating section (3), wherein: said exchanging section (2) contains a bundle of U-tubes (4) fed with an evaporable liquid medium such as water (W) and exposed to a hot gas (G) flowing in a hot chamber around said tubes, so that said medium is partially evaporated in the tubes while recovering heat from hot gas flowing in the hot chamber (7); said separating section (3) comprises a collection chamber (16) in communication with outlet of the tubes (4) to receive the partially evaporated medium leaving the tubes; said separating section (3) is arranged to provide separation of vapour fraction and liquid fraction from the partially evaporated medium at least partially by gravity; the apparatus also comprises means for controlling the liquid level in the collection chamber and for a partial recycle of the non-evaporated liquid.

A shell-and-tube heat exchanger comprises a shell enclosing a plurality of U-shaped tubes. Each tube is provided with a first portion and with a second portion. The open ends of each tube are connected to a tube-sheet. A pressure chamber is connected to the tube-sheet. The pressure chamber contains a guiding jacket that, at a first end thereof, is sealingly joined to the tube-sheet or the first tube portions and, at a second end thereof that is opposite to the first end, is open. The guiding jacket splits the pressure chamber into a first section and a second section. The first section and the second section are in communication with each other by means of the open end of the guiding jacket. The first section is provided with a liquid level, located below the open end, and therefore with a vapour chamber, located above the liquid level.

A vaporizer apparatus for vaporizing liquefied natural gas (LNG) into vapor-phase natural gas for injection into an oil or gas well, comprises a blower assembly, a burner section, a heat exchanger section, and at least one flammable gas concentration sensor. The blower assembly comprises a primary blower configured to move air along an air flow path through the vaporizer apparatus and a flame arrestor configured to allow passage of the air into the vaporizer apparatus and impede passage of a flame out of the vaporizer apparatus. The burner section comprises an enclosure having an upstream end coupled to the blower assembly and a downstream end, and a burner inside the enclosure and in the air flow path for heating the air. The heat exchanger section comprises an enclosure having an upstream end coupled to the downstream end of the burner section enclosure and a downstream end, and at least one LNG heat exchange tube inside the enclosure and in the air flow path, and thermally communicable with the air heated by the burner. The at least one flammable gas concentration sensor is in the air flow path upstream of the burner and is configured to detect whether a concentration of a flammable gas in the air is above a flammable gas concentration set point.