A boiler includes an upper steam drum, an optional intermediate drum, and a lower drum. Each drum is divided by an internal divider into a clean section and a concentrated section. Downcomers connect the upper steam drum to the lower drum, and tubes are connected to convey a heated steam-water mixture from the lower drum into the upper steam drum (through the optional intermediate drum, if provided). An optional superheater has an input terminal connected to receive steam from the clean section of the upper steam drum. An attemperator may be provided to attemperate superheated steam output from an output terminal of the superheater, and the attemperation fluid may optionally be provided from the concentrated side of the upper steam drum.

A process for in situ thermal recovery of hydrocarbons from a reservoir is provided. The process includes: providing an oxygen-enriched mixture, fuel, feedwater and an additive including at least one of ammonia, urea and a volatile amine to a Direct-Contact Steam Generator (DCSG); operating the DCSG, including contacting the feedwater and the additive with hot combustion gas to obtain a steam-based mixture including steam, CO.sub.2 and the additive; injecting the steam-based mixture or a stream derived from the steam-based mixture into the reservoir to mobilize the hydrocarbons therein; and producing a produced fluid including the hydrocarbons.

A process for in situ thermal recovery of hydrocarbons from a reservoir is provided. The process includes: providing an oxygen-enriched mixture, fuel, feedwater and an additive including at least one of ammonia, urea and a volatile amine to a Direct-Contact Steam Generator (DCSG); operating the DCSG, including contacting the feedwater and the additive with hot combustion gas to obtain a steam-based mixture including steam, CO.sub.2 and the additive; injecting the steam-based mixture or a stream derived from the steam-based mixture into the reservoir to mobilize the hydrocarbons therein; and producing a produced fluid including the hydrocarbons.

A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

A system for deriving 100% quality steam for steam assisted gravity drainage (SAGD) injection or other applications features a once through steam generator (OTSG), a steam-water separator connected downstream of the OTSG's radiant tubes to separate steam and water from a two-phase flow received therefrom, superheater tubes installed in the convection section and connected to a steam outlet of the steam-water separator in downstream relation thereto to receive and heat dried steam therefrom to a superheated state, and a desuperheater connected downstream of the superheater tubes to receive the superheated steam therefrom and use same to vaporize blowdown water from the steam-water separator, whereby the vaporized blowdown water and the superheated steam collectively form a superheated steam output for the intended application, typically after additional separation of solid particles therefrom for optimal steam quality.

A system for deriving 100% quality steam for steam assisted gravity drainage (SAGD) injection or other applications features a once through steam generator (OTSG), a steam-water separator connected downstream of the OTSG's radiant tubes to separate steam and water from a two-phase flow received therefrom, superheater tubes installed in the convection section and connected to a steam outlet of the steam-water separator in downstream relation thereto to receive and heat dried steam therefrom to a superheated state, and a desuperheater connected downstream of the superheater tubes to receive the superheated steam therefrom and use same to vaporize blowdown water from the steam-water separator, whereby the vaporized blowdown water and the superheated steam collectively form a superheated steam output for the intended application, typically after additional separation of solid particles therefrom for optimal steam quality.

A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

A boiler facility includes a boiler having a combustion chamber in which a burner is installed, a fuel pipe for supplying fuel to the burner, an air duct for supplying air sucked by a blower to the boiler, an oxygen supplier having an oxygen pipe connected to the air duct and a flow rate controller provided in the oxygen pipe, and a control unit. The control unit sets an air amount that is smaller than the reference air amount for burning the fuel, and controls the blower so that the set air amount is supplied to the boiler. Further, the control unit sets an oxygen amount for fuel combustion, and controls the flow rate controller so that the set oxygen amount is supplied to the air duct.