The present invention provides a device which comprises: a heat exchanger (1) for transferring heat of a heat-supplying medium to a working medium which differs from said heat-supplying medium, a first supply device designed to provide a flow of the heat-supplying medium at a first temperature from a heat source to the heat exchanger, and a second supply device which is designed to deliver the heat-supplying medium after it has passed through the heat exchanger, and/or a further medium at a second temperature lower than the first temperature, to the flow of the heat-supplying medium at the first temperature.

The current invention discloses a method and apparatus for production of hot water or steam in a 4-pass firetube boiler. A waste heat stream is passed through the first and second passes of the boiler, and then routed into a furnace tube (which is the third pass of the boiler) to help suppress the flame temperature and NOx emissions from the burner. The flue gas from the third pass is then passed through the fourth pass of the boiler to transfer the heat energy to the water in the boiler.

Method and system for adjusting a measured reheat outlet steam temperature (R.sub.PV) to approximate a reheat outlet steam temperature setpoint (R.sub.SP) in a boiler. An R.sub.PV is compared to an R.sub.SP. If the R.sub.PV is less than the R.sub.SP and a position of a fuel nozzle tilt (TILT.sub.PV) is below a high limit of the fuel nozzle tilt (TILT.sub.HIGH), the TILT.sub.PV is increased while a flow rate of a secondary flue gas recirculation (SFGR.sub.PV) is kept constant. If the R.sub.PV is less than the R.sub.SP and the TILT.sub.PV is at the TILT.sub.HIGH, the SFGR.sub.PV is increased. If the R.sub.PV is greater than the R.sub.SP and the SFGR.sub.PV is greater than a low limit of flow rate of the SFGR (SFGR.sub.LOW), the SFGR.sub.PV is decreased, while the TILT.sub.PV is kept constant. If the R.sub.PV is greater than the R.sub.SP and the SFGR.sub.PV is at the SFGR.sub.LOW, the TILT.sub.PV is decreased.

A system for providing wind-assisted air supply to coal-fired power plants through the use of a wind funnel communicating with an air handler system of a coal-fired boiler is disclosed. The shape, size and orientation of the wind funnel may be controlled in order to optimize the collection of wind and generation of increased air pressure for delivery to the coal-fired boiler system. Increased operating efficiency of coal-fired power plants may be achieved with the wind funnel system.

The current invention discloses a method and apparatus for production of hot water or steam in a 4-pass firetube boiler. A waste heat stream is passed through the first and second passes of the boiler, and then routed into a furnace tube (which is the third pass of the boiler) to help suppress the flame temperature and NOx emissions from the burner. The flue gas from the third pass is then passed through the fourth pass of the boiler to transfer the heat energy to the water in the boiler.

A supercritical steam generator includes a downdraft furnace enclosure, a hopper tunnel, and a convection pass enclosure, with the hopper tunnel joining the downdraft furnace enclosure and convection pass enclosure together. Flue gas passes down through the downdraft furnace enclosure through the hopper tunnel and up through the convection pass enclosure. This structure permits the outlet steam terminals, which provide access to the resultant supercritical steam and/or reheat steam, to be located at a base of the steam generator rather than at the top of the steam generator as with conventional boilers. This reduces the length of the steam leads from the steam generator to a steam turbine that produces electricity using the supercritical steam.

A process for combusting a high-moisture fuel to generate steam, the process comprising heating a high-moisture solid fuel while contacting the high-moisture solid fuel with an oxygen-depleted gas stream to produce a dried solid fuel and a moist oxygen-depleted gas stream; combusting the dried solid fuel with a combustion air stream to produce a combustion products stream; transferring heat to generate steam by indirect heat exchange with the combustion products stream; dividing the combustion products stream into a first portion and a second portion; transferring heat to the recirculating thermal fluid by indirect heat exchange with the first portion of the combustion products stream; and transferring heat to preheat the combustion air stream by indirect heat exchange with the second portion of the combustion products stream; and recombining the first portion of combustion products stream and the second portion of the combustion products stream.