A small supercritical once-through steam generator (OTSG) includes a radiant section with a furnace coil, and a convection section downstream of the radiant section that includes a superheater which is fluidically connected to the furnace coil. Optionally, the OTSG is devoid of a steam separator. An economizer can also be included downstream of the superheater. Supercritical steam can be generated using the OTSG, for use, among other things, in enhanced oil recovery applications.

An apparatus for using a water coil air heater with a single bank economizer. A boiler economizer arrangement includes an economizer bank which has separate hot pass bank and cold pass bank economizer portions in a parallel arrangement, each facing the same flow of hot flue gas. Feedwater enters the cold pass bank economizer where it is heated by the hot flue gas, and then flows to a water coil air heater away from the hot flue gas. The feedwater dissipates heat energy in the water coil air heater which may be used to heat air bound for combustion. The feedwater continues into the hot pass bank economizer portion of the economizer arrangement where it absorbs additional heat from the flue gas. The heated feedwater flows out of the economizer arrangement and may be subject to additional heating by a boiler or other heat exchanger.

An apparatus for using a water coil air heater with a single bank economizer. A boiler economizer arrangement includes an economizer bank which has separate hot pass bank and cold pass bank economizer portions in a parallel arrangement, each facing the same flow of hot flue gas. Feedwater enters the cold pass bank economizer where it is heated by the hot flue gas, and then flows to a water coil air heater away from the hot flue gas. The feedwater dissipates heat energy in the water coil air heater which may be used to heat air bound for combustion. The feedwater continues into the hot pass bank economizer portion of the economizer arrangement where it absorbs additional heat from the flue gas. The heated feedwater flows out of the economizer arrangement and may be subject to additional heating by a boiler or other heat exchanger.

A boiler system and methods for heating a fluid are disclosed, in particular for heating water for producing steam. The boiler comprises an economizer module integrated on the top of a furnace, and is in communication with the furnace to receive heat and/or hot combustion gases therefrom. The economizer comprises tubes receiving the fluid, such as feedwater, to be pre-heated and providing it to the furnace comprising a combustion chamber producing heat and hot combustion gases. The fluid is pre-heated by circulating first through the pre-heating tube assembly of the economizer module before entering the furnace module where the fluid is further heated by the combustion chamber. Since the economizer is located on the furnace module, the boiler does not have a large footprint compared to a regular boiler system without an economizer. Due to the total integration of the economizer with the furnace, the boiler system has improved energy efficiency.

A boiler system and methods for heating a fluid are disclosed, in particular for heating water for producing steam. The boiler comprises an economizer module integrated on the top of a furnace, and is in communication with the furnace to receive heat and/or hot combustion gases therefrom. The economizer comprises tubes receiving the fluid, such as feedwater, to be pre-heated and providing it to the furnace comprising a combustion chamber producing heat and hot combustion gases. The fluid is pre-heated by circulating first through the pre-heating tube assembly of the economizer module before entering the furnace module where the fluid is further heated by the combustion chamber. Since the economizer is located on the furnace module, the boiler does not have a large footprint compared to a regular boiler system without an economizer. Due to the total integration of the economizer with the furnace, the boiler system has improved energy efficiency.

Heat recovery steam generator comprises a casing, low-pressure evaporator coils, preheater booster coils upstream thereof and feedwater heater coils downstream thereof, a water-to-water heat exchanger having low and high temperature paths; a first conduit from the preheater to the high-temperature path, and a second conduit from the feedwater heater to the preheater. A conduit can extend from feedwater heater to low-pressure evaporator. A conduit can extend from the water-to-water heat exchanger to the feedwater heater. High-pressure economizer coils can be upstream of the preheater, with a conduit exiting the feedwater heater to the high-pressure economizer. Additional coils can be upstream of the high-pressure economizer. The feedwater heater can comprise first and second sections, or first, second and third sections; or more sections. The connections among the various components and sections can be near their upstream and downstream faces.

Heat recovery steam generator comprises a casing, low-pressure evaporator coils, preheater booster coils upstream thereof and feedwater heater coils downstream thereof, a water-to-water heat exchanger having low and high temperature paths; a first conduit from the preheater to the high-temperature path, and a second conduit from the feedwater heater to the preheater. A conduit can extend from feedwater heater to low-pressure evaporator. A conduit can extend from the water-to-water heat exchanger to the feedwater heater. High-pressure economizer coils can be upstream of the preheater, with a conduit exiting the feedwater heater to the high-pressure economizer. Additional coils can be upstream of the high-pressure economizer. The feedwater heater can comprise first and second sections, or first, second and third sections; or more sections. The connections among the various components and sections can be near their upstream and downstream faces.

A control method for operating a heat recovery steam generator having a flue gas channel in which an evaporator, having at least two evaporator heating surfaces arranged successively in the flue gas channel and at least one intermediate heating surface arranged between the evaporator heating surfaces, is provided, the method including determining a characteristic value characteristic of the heat absorption in the evaporator for the evaporator heating surfaces, additionally determining for the at least one intermediate heating surface, an additional characteristic value for the heat absorption of the intermediate heating surface, and subtracting this additional characteristic value from the characteristic value characteristic of the heat absorption in the evaporator.

A control method for operating a heat recovery steam generator having a flue gas channel in which an evaporator, having at least two evaporator heating surfaces arranged successively in the flue gas channel and at least one intermediate heating surface arranged between the evaporator heating surfaces, is provided, the method including determining a characteristic value characteristic of the heat absorption in the evaporator for the evaporator heating surfaces, additionally determining for the at least one intermediate heating surface, an additional characteristic value for the heat absorption of the intermediate heating surface, and subtracting this additional characteristic value from the characteristic value characteristic of the heat absorption in the evaporator.

An energy-saving gas supply boiler system, comprising: a steam boiler, a flue gas pipeline, a heat exchanger, a steam generator and an ejector. The steam boiler comprises a body, a combusting apparatus, a flue gas outlet, a water outlet and a high pressure steam outlet. The heat exchanger comprises a high temperature flue gas inlet, a medium temperature flue gas outlet, a cooling water inlet and a hot water outlet. Cooling water undergoes heat exchange with flue gas and flows out from the hot water outlet. The steam generator comprises a generator body, a hot water inlet and a low pressure steam outlet. The ejector comprises a high pressure steam inlet, a mixing steam outlet and a low pressure steam inlet. The high pressure steam inlet delivers high pressure steam to the ejector. The low pressure steam inlet delivers low pressure steam to the ejector.