Abstract: A method removes combustion residues from a wall of a chamber which carries combustion gases and/or from at least one component which is disposed in the chamber. The method includes making contact between the combustion residues and a first cleaning medium, and making contact between the pretreated combustion residues and a second cleaning medium. The first cleaning medium and the second cleaning medium differ at least with regard to a physical state. An apparatus for removing the combustion residues has different cleaning appliances and operating areas which at least partially overlap. The method and the apparatus allow, for example, heat exchanging surfaces in steam generators to be cleaned in a particular careful and thorough manner.

Abstract: A method removes combustion residues from a wall of a chamber which carries combustion gases and/or from at least one component which is disposed in the chamber. The method includes making contact between the combustion residues and a first cleaning medium, and making contact between the pretreated combustion residues and a second cleaning medium. The first cleaning medium and the second cleaning medium differ at least with regard to a physical state. An apparatus for removing the combustion residues has different cleaning appliances and operating areas which at least partially overlap. The method and the apparatus allow, for example, heat exchanging surfaces in steam generators to be cleaned in a particular careful and thorough manner.

Abstract: A fuel control system for delivering gaseous fuel from a source to a gas-operated engine that includes a normally open electronic control valve connected between the fuel source and the engine, and responsive to electronic valve control signals for variably closing connection between the source and the engine. An electronic control unit supplies the electronic valve control signals responsive to engine operation. The electronic control unit includes facility for responding to termination of engine operation by automatically generating a valve control signal to hold the valve fully closed for a preselected time duration. This preselected time duration preferably includes a fixed minimum time duration and a user-programmable additional valve closure time duration.