Process for removing dissolved gas from an evaporator feed stream

A method of treating a feedwater stream with an evaporator comprising:

• directing the feedwater stream to and through a deaerator;
• after directing the feedwater stream to and through the deaerator, directing the feedwater stream to the evaporator;
• evaporating the feedwater stream in the evaporator and producing a concentrate and steam;
• directing at least a portion of the steam produced by the evaporator through a steam line to and through the deaerator and stripping dissolved gas from the feedwater stream passing through the deaerator;
• maintaining the vapor pressure in the deaerator at less than atmospheric pressure;
• maintaining the temperature of the vapor in the deaerator at less than 100° C.;
• and
• prior to the feedwater stream entering the deaerator, heating the feedwater stream to a temperature greater than the saturated vapor temperature in the deaerator.

A method of recovering oil from an oil well, comprising:

• recovering an oil-water mixture from the well;
• separating the oil-water mixture to produce an oil product and produced water;
• directing the produced water to and through a deaerator;
• after the produced water has been directed through the deaerator, directing the produced water to an evaporator and producing a concentrated brine and steam;
• condensing the steam to form a distillate;
• directing the distillate to a steam generator and producing steam;
• injecting at least a portion of the steam into an injection well;
• venting steam from the evaporator to form vent steam and directing the vent steam through a vent steam line to the deaerator;
• directing the vent steam through the deaerator and stripping dissolved gases from the produced water passing through the deaerator;
• maintaining the vapor pressure in the deaerator below atmospheric pressure;
• maintaining a vapor temperature in the deaerator below 100° C.;
• maintaining the vapor pressure in the deaerator below atmospheric pressure and maintaining the vapor temperature in the deaerator below 100° C. is accomplished, in part at least, by subjecting the vent steam in the vent steam line to a pressure drop at a point between the evaporator and the deaerator;
• and
• heating the produced water to a temperature greater than the saturated vapor temperature in the deaerator and greater than 100° C. before the produced water enters the deaerator.