Method for feed water control in waste heat steam generators

Abstract

In a method for feed water control in waste heat steam generators, in particular drum boilers with a circulating pump (9) and drum boilers with natural circulation employed in combination power plants, wherein, by a three-component control by means of a superordinated level regulator (13) and a flow-through regulator (14) subordinated to the level regulator (13), the set value (S.sub.in) of the flow-through regulator (14) is displaced by the level regulator (13) in such a way that the level in the drum (6) is always regulated to the set value (S), regardless of interfering effects, the flow-through regulator (14) for the feed water flow (m.sub.s) is guided by the heat amount (Q.sub.AG) in the exhaust gas flow. The output signal of the flow-through regulator (14) for the feed water flow (m.sub.s) is limited, wherein as the function of the heat amount (Q.sub.AG) in the exhaust gas flow a selection is made between a limit value (m.sub.1) for the start-up operation and a limit value (m.sub.2) for normal control operation and the switch from (m.sub.1) to (m.sub.2) takes place via a time function element (16) with an idle time (T).

Dependencies are inferred from the claim text.