Forced circulation steam generator

Abstract

Forced circulation steam generators of any design may increase effective heat absorption and steaming capacity by maintaining bulk boiler water temperature at or near the saturation temperature for the operating pressure, while the main boiler heat transfer process is substantially reserved for the evaporative function. The acceleration of gas-to-liquid energy transfer across boiler heating surfaces occurs when bulk boiler water temperature is maintained at or near saturation, and significant degrees of nucleate boiling and nucleate film boiling heat transfer exist while stable steam film boiling is limited. In one form of the invention, recirculating boiler water is discharged from a circulating pump through an exterior ejector-type contact heat exchanger to mix with recirculated heating steam before being returned to the boiler. In this adaptation bulk boiler water temperature may be closely controlled by regulating the quantity of heating steam admitted into the ejector heat exchanger. In another form of the invention, recirculated boiler water is discharged from a circulating pump through an ejector-type contact heat exchanger which is mounted internally within the boiler steam spaces, where it mixes with heating steam before being returned to the bulk boiler water body at or near the saturation temperature. In this variation the ejector heat exchanger discharge is automatically kept at or near the saturation temperature, and no valve regulating means is required to control the quantity of heating steam.

Dependencies are inferred from the claim text.