Abstract: A thermal power plant has an exhaust gas system, a feed-water system, a high-pressure feed-water heater provided to the feed-water system, a main economizer, a catalytic NOx removal equipment, and a sub economizer. The main economizer is provided to the secondary side of the high-pressure feed-water heater of the feed-water system and increases the temperature of the feed-water by using the residual heat of the combustion gas from the boiler. The catalytic NOx removal equipment is provided to the secondary side of the main economizer of the exhaust gas system. The exhaust gas is supplied to the catalytic NOx removal equipment at a required temperature or higher. The sub economizer is provided between the high-pressure feed-water heater and the main economizer and increases the temperature of water by using the exhaust gas on the secondary side of the NOx removal equipment.

Abstract: The present invention relates to a method and a boiler for decreasing the amount of nitrogen oxides in flue gases of a boiler, which flue gases are generated in the combustion of fuels and air. The boiler has a water circulation system comprising superheaters (8) and a furnace (1) for combustion of fuel and for generating flue gases that contain nitrogen oxides, which flue gases mainly flow upwards in the furnace and further to the superheater zone and via other heat recovery surfaces of the boiler out of the boiler, and a nitrogen oxides reducing agent is introduced into the flue gases. It is essential that the nitrogen oxides reducing agent is introduced into the flue gases prior to the superheater zone, before which the temperature of the flue gases is decreased by means of at least one heat exchanger (15) that is located in the flue gas flow upstream of the introduction of the reducing agent, for obtaining a suitable temperature window in the flue gas flow in order to reduce nitrogen oxides.

Abstract: A small supercritical once-through steam generator (OTSG) includes a radiant section with a furnace coil, and a convection section downstream of the radiant section that includes a superheater which is fluidically connected to the furnace coil. Optionally, the OTSG is devoid of a steam separator. An economizer can also be included downstream of the superheater. Supercritical steam can be generated using the OTSG, for use, among other things, in enhanced oil recovery applications.

Abstract: A process and a reactor for the of a carbonaceous feed. The reactor has a reactor chamber; steam generating heat exchange units; at least one steam drum; and recirculation lines for circulating water and steam between one or more of the heat exchange units and the steam drum. The steam drum further includes a steam feed line for transporting steam via a heat exchange unit and a superheated steam line to a superheated steam header. The superheated steam line is split into a return line leading to a heat exchange line through the steam drum, and a header feed line.

Abstract: A once-through steam generator comprises a duct having an inlet end in communication with a source of a hot gas; and a tube bundle installed in the duct and comprising multiple heat transfer tubes. The tube bundle has an economizer section, an evaporator section, and a superheater section. A steam separating device may be positioned between the evaporator section and the superheater section, wherein, as part of a wet start-up, hot water collected by the steam separating device is delivered from the steam separating device to mix with cold feedwater before it is introduced into the economizer section. A start-up module may be positioned in the duct near the inlet end, wherein, as part of a dry start-up, cold feedwater is delivered into the start-up module to generate hot water that is then mixed into the feedwater stream before it is introduced into the economizer section.

Abstract: The disclosure provides an M-type pulverized coal boiler suitable for ultrahigh steam temperature. The pulverized coal boiler comprises a hearth of which the bottom is provided with a slag hole and a tail downward flue of which the lower part is provided with a flue gas outlet. The pulverized coal boiler further comprises a middle flue communicated between the hearth and the tail downward flue, wherein the middle flue comprises an upward flue and a hearth outlet downward flue of which the bottoms are mutually communicated and the upper ends are respectively communicated with the upper end of the hearth and the upper end of the tail downward flue to form a U-shaped circulation channel.

Abstract: A method for positioning superheaters (2, 3, 4, 5) in biomass burning steam generators, and a steam generator. The steam generator comprises a combustion chamber (1), a flue gas duct (6), a steam circuit (7), and the superheaters (2, 3, 4, 5) positioned for minimizing corrosion at a high temperature. The steam generator is fitted with at least two superheaters (2, 3, 4, 5), whose positioning in the flue gas duct (6) and serial arrangement in the steam circuit (7) are effected in such a way that the superheater's or superheaters' heat transfer surface has its surface temperature remaining below the melting point of KOH, 406° C. (corresponds to a steam temperature of about 350-380° C.) down to the point in the flue gas duct (6), at which the flue gases' temperature has fallen to 750° C. While the flue gases are within the range of less than 750° C.

Abstract: This invention provides a superheated steam apparatus that is capable of efficiently heating water to generate superheated steam, and to perform a process such as sterilization utilizing this superheated steam while keeping the loss of heating energy to a minimum.

Abstract: A steam generator has a combustion chamber which is configured for an approximately horizontal main direction of flow of the fuel gas and which is followed on the fuel-gas side, via a horizontal gas flue, by a vertical gas flue. The containment walls of the combustion chamber are formed from evaporator tubes. Temperature differences between adjacent evaporator tubes of the combustion chamber are to be kept particularly low in all the load states of the steam generator. For this purpose, a first group and a second group of evaporator tubes can be acted upon in each case in parallel by a flow medium. The first group of evaporator tubes is connected in series with the second group.

Abstract: For achieving a high plant efficiency, a waste-heat steam generator, in particular for a combined-cycle power plant, has a number of heating surfaces heatable by a flue gas and carrying a medium to be heated. The steam generator can be operated at critical or supercritical pressures and has a once-through evaporator connected in countercurrent to the flue gas provided on a medium side. The evaporator is followed by a preheater and preceded by a superheater on a flue-gas side.

Abstract: In a steam generator having a convective part arranged downstream of the furnace chamber and essentially consisting of final superheater (1), pre-superheater, evaporator and economizer connected in series on the flue-gas side, a further contact heat exchanger (5) having a plurality of tube banks (10) is arranged upstream of the final superheater (1). This contact heat exchanger (5) is connected to the steam drum (6) in such a way that it can be operated as both an evaporator and a superheater. The working medium to be heated flows in parallel from the bottom to the top through the tube banks (10), as a rule arranged vertically or inclined, of the contact heat exchanger in the evaporator circuit and flows in series through said tube banks (10) of the heat exchanger in the superheater circuit.

Abstract: An increased efficiency boiler is provided, which, instead of trying to eliminate steaming in the economizer, designs the economizer to permit steaming, and a control is provided for the boiler which takes into account the heat input to the boiler as well as the water level in the steam drum and the reliability of the economizer.

Abstract: A single-drum recovery boiler comprising a superheater (2), boiler bank elements (3a) forming a boiler bank, and elements (3b) forming an economizer. In the recovery boiler, a plurality of boiler bank elements (3a) and economizer elements (3b) are disposed alternately so that a boiler bank--economizer unit (3) is achieved where the ratio between the boiler bank elements and the economizer elements is optimized in relation to the operating conditions of the boiler.

Abstract: A reheat steam temperature control system that utilizes the separate components of a reheater and a reheat heat exchanger to generate hot reheat steam. The reheater uses the fluidized bed as its source of heat while the reheat heat exchanger uses main steam as its source of heat. A bypass control valve is operated to divert the required amount of main steam to the reheat heat exchanger depending on operating conditions. Should the temperature of the hot reheat steam be too low, additional main steam is delivered to the reheat heat exchanger. Conversely, should the temperature of the hot reheat steam be too high, the amount of main steam delivered to the reheat heat exchanger is reduced. Attemperators are used within both the reheating circuit and the main steam circuit to temper the fluctuations of their respective steam.

Abstract: A recirculation apparatus is employed to recirculate a portion of the feedwater in a vertical-tube economizer to reduce the likelihood of reverse flow and steaming at startup and/or low load. A recirculation valve, opened at low load, directs part of the water from the economizer outlet back to the inlet of the boiler feed pump via a deaerator. The recirculated water not only increases the pumping head across the economizer tube planes, but also reduces the temperature rise of the increased water flow rate passing through the economizer tubes which now enters the economizer tube bank at an elevated temperature. The reduced temperature rise in a given single pass through a tube plane consequently reduces the buoyant force which opposes the pumping head in downflowing tube planes. Additionally, the amount of water being recirculated at these light load conditions results in a total boiler feed pump flow which is well within the capacity of a given pump size without consideration of the present invention.