Abstract: An apparatus for introducing gas recirculation into a furnace to control steam temperature includes a hot air chamber for receiving hot air from an air preheater. The hot air chamber has at least one outlet communicating with the interior of the furnace. The apparatus includes a recirculation gas chamber for receiving recirculation gas from a recirculation fan and includes at least one outlet communicating with the interior of the furnace. Each of the chambers is disposed about at least a portion of the circumference of the furnace with one of the chambers disposed above at least a portion of the other. Ducts are provided between the hot air chamber and the air preheater and between the recirculation gas chamber and the recirculation fan to provide communication between the elements. A passageway is disposed between the hot air chamber and the recirculation gas chamber.

Abstract: An arrangement for utilizing the heat contained in the exhaust gas from a coal-fired boiler for preheating feed water for the boiler and for preheating primary air. The arrangement includes a rotating heat transfer unit and lines for conducting exhaust gas and preheated combustion air to the heat transfer unit. A heat shifting unit is connected in parallel to the heat transfer unit. A line conducts primary air to the heat shifting unit and another line conducts cooled exhaust gas from the heat transfer unit to the heat shifting unit. The exhaust gas line and the cooled exhaust gas line connecting the heat transfer unit and the heat shifting unit are connected through a bypass which bridges the heat transfer unit. The bypass includes a heat exchanger and/or steam generator, wherein the boiler feed water flows through the heat exchanger and/or steam generator.

Abstract: The vapor pump constituted by a mass and heat exchanger comprises an outer enclosure, a set of exchanger tubes disposed inside the enclosure and extending lengthwise therein, opening out at one of the ends in a first radial plane and at their other ends in a second radial plane, which radial planes include means for positioning and supporting the tubes and for closing the empty spaces in the section of the enclosure situated outside the tubes, thereby defining between said radial planes both a first gaseous fluid flow circuit inside the tubes, and a distinct counterflow second fluid flow circuit inside the enclosure but outside the tubes. One of the first and second gaseous fluids constituted by moist hot combustion products from a thermal process while the other gaseous fluid is constituted by new combustion air. Humidifier means are provided for humidifying the air inserted into the enclosure.

Abstract: A plant having a combustion chamber can employ at least one heat pipe. The heat pipe is mounted to exchange heat between flue gas in a flue gas path and combustion air in a combustion air path. A protection system has a dual passage for separately conducting the flue gas and the combustion gas. The dual passage has a wall separating the flue gas path from the combustion air path. The heat pipe is mounted through the wall. A sensor is mounted about the heat pipe for providing a temperature signal signifying the temperature at the heat pipe. A damper is coupled to the sensor and communicates with the dual passage for mixing relatively cooler air with the flue gas in the dual passage, upstream of the heat pipe, in response to the temperature signal violating a predetermined limit.

Abstract: A gas fired boiler for a domestic hot water and/or central heating system has a burner (25) (FIG. 1), a static heat exchanger (22) through which water is circulated, and a rotary heat exchanger (12) of which the body is a disc of ceramic material such as is currently used for catalytic conversion in automobile exhaust systems. The rotary heat exchanger recovers heat from the gases passing from the static heat exchanger (22) to the outlet flue 4, and uses this recovered heat for heating the fresh air entering through the air intake (3). A conduit (90) having a controllable valve (91) enables heated fresh air to be supplied for space heating purposes if required, while improving the thermal efficiency of the boiler by promoting condensation of water vapor from the combustion gases as they pass through the rotary heat exchanger.

Abstract: A compact and maintenance-free means and method of regenerating the sensible heat from flue gases of fossil fuel furnaces by heat exchange through two circular layers of rock beds rotating under two semi-circular mantles with the first mantle applying hot flue gases to the beds and the second withdrawing preheated ambient air needed for combustion by said furnaces. When used for power plant flue gas treatment, layers of acid-resistant pipes containing boiler feedwater are sandwiched between the two rock bed layers to usefully recover the heat units arising from moisture condensation. The enormous water of condensation collects flyash and sulphur dioxide thus removing these pollutants from the stack gases. The heavy rock beds rotate slowly beneath the fixed mantles in a circular, pan-shaped, steel vessel floating on and cooled by a circular pond of water. Friction of rotation is minimal and gas leakage principally prevented by liquid seals.

Abstract: A compact and maintenance-free means and method of regenerating the sensible heat from flue gases of fossil fuel furnaces by heat exchange through two circular layers of rock beds rotating under two semi-circular mantles with the first mantle applying hot flue gases to the beds and the second withdrawing preheated ambient air needed for combustion by said furnaces. When used for power plant flue gas treatment, layers of acid-resistant pipes containing boiler feedwater are sandwiched between the two rock bed layers to usefully recover the heat units arising from moisture condensation. The enormous water of condensation collects flyash and sulphur dioxide thus removing these pollutants from the stack gases. The heavy rock beds rotate slowly beneath the fixed mantles in a circular, pan-shaped, steel vessel floating on and cooled by a circular pond of water. Friction of rotation is minimal and gas leakage principally prevented by liquid seals. When flue gas temperature rises, as above 600 degrees F.

Abstract: In the recovery of waste heat from flue gas containing particulate solids, CO.sub.2, SO.sub.2, SO.sub.3 and H.sub.2 O, several improvements are provided, e.g., passing hot flue gas, e.g., from a power plant, over heat exchange surface attackable by sulfuric acid, e.g., in a combustion air preheater, so as to release heat to said heat exchange surface and to partially cool said flue gas to a temperature within the range of about 350.degree. F.

Abstract: In a method in the operation of a firing plant of the type comprising a combustion furnace and heat exchanger means to transfer thermal energy from the flue gas of the furnace to its combustion air, wherein a vaporizable liquid, such as water, is added to the combustion air of the furnace, the combustion air pressure is reduced in the portion of the heat exchanger means where the said liquid is caused to evaporate, the necessary evaporation heat being taken from the flue gas of the furnace before the flue gas is discharged to the atmosphere. A plant for performing the method is characterized by containing a pump (11) which has a relatively small inlet opening (10) so that the pump (11) creates a negative pressure in the portion (12) of the heat exchanger (9) where the liquid, fed by means of a nozzle (13), evaporates. This allows large amounts of water to evaporate, and flue gas, which flows through the heat exchanger portion (14), is cooled to a low temperature.

Abstract: In an air heater, mixers of hot and cold air are built into circulating air ducts between the passes of that portion of the air heater which is exposed to the danger of corrosion. Said mixers are provided in the form of tubes perforated lengthwise and located frontally in the respective pass. Headers serving the mixers are connected to cold air feeding ducts.Perforations the tubes of each mixer are provided with serve to direct jets of cold air at right angles to the flow of hot air.The tubes of the mixer are blanked off at the opposite ends of the adjacent tubes while the open ends of these tubes are connected to different cold air headers. Used as the tubes of a mixer can be a bunch of frontal tubes in the respective passes of the air heater.The air heater disclosed offers protection against corrosion by heating a mixture of cold and hot air to a minimum temperature, and said protection is achieved in a compact light-weight apparatus requiring minimum labor for its fabrication.

Abstract: A recuperator for recovering heat from hot exhaust gases flowing through a flue comprises inner and outer cylindrical walls coaxially surrounding a portion of the flue to which a plurality of fins are fixed, the fins extending longitudinally of the flue and being grouped such that fins spaced circumferentially around one section of the flue are angularly staggered with respect to fins spaced circumferentially around an adjacent section of the flue, the recuperator being arranged such that cold gas can be passed into, and is preheated as it flows along, an outer annular space between the said walls, the gas passing into an inner annular space containing the fins which cause turbulence and increase the heat-transfer by convection and radiation to the gas, and the heated gas being emitted through an outlet.

Abstract: Heat is recovered from the flue gas stream discharged from a power plant combustion zone by heat exchange of the flue gas stream against the air stream which enters the combustion zone. Each gas stream flows through two rotating air preheaters, with a first preheater rotating at a constant rate and a second preheater rotating at a variable rate. The rate of rotation of the second preheater is varied to adjust the temperature of either the heated air stream or the temperature of the flue gas stream after passage through the preheaters.

Abstract: In a pulverized fuel-fired steam generator, a steam air heater is disposed in the air inlet duct to the main air heater. Steam from an auxiliary in-plant source or from the boiler itself is passed through the steam air heater thereby increasing the temperature of the air entering the main air heater. The flow rate of steam passed through the steam air heater is regulated to maintain the flue gas temperature entering dust collection equipment located in the flue gas stream downstream of the main air heater above the dew point of water vapor and the condensation point of sulfuric acid during start-up and low load operations.

Abstract: A system for recovering the waste heat normally exhausted into the atmosphere by chemical or other processing plants. The invented system comprises a heat exchange apparatus located in the exhaust stack or flue passage, heat transfer means for carrying the waste heat absorbed from the exhaust gases to a location remote therefrom, and a second heat exchange apparatus for releasing the transferred waste heat for beneficial use at said remote location. The present invention also includes temperature and pressure control means which enhance the safety and efficiency of the system's operation. The heat transfer means disclosed in this invention is a high temperature liquid (and associated pumping and piping means) capable of withstanding temperature up to 900 F. without flashing, changing state, or corroding the heat exchange apparatuses.

Abstract: A heat recovery system is provided for recovering heat from flue gases and the like and heating combustion air or the like in the form of a flue gas conduit receiving hot flue gas from a furnace or the like, a metallic recuperator receiving hot flue gas from said flue gas conduit, a ceramic regenerator selectively receiving at least a part of the hot flue gas leaving the metallic recuperator, by-pass means in parallel with the ceramic regenerator receiving any of the flue gas leaving the metallic recuperator which does not go through the ceramic regenerator, stack means receiving the flue gas from the by-pass means and the ceramic regenerator means for discharge to the atmosphere, means delivering air to be heated in parallel to the ceramic regenerator and the metallic recuperator, and conduit means receiving and combining heated air from the ceramic regenerator and the metallic recuperator for delivery to a point of use.

Abstract: A corrugated plate heat exchanger for effecting temperature transfer between two isolated fluids. The heat exchange elements comprise a plurality of elongated corrugated plates arranged to provide dual isolated flow channels therethrough. The arrangement of the corrugated plates also provides the capability of introducing the first fluid through one end of the exchanger and out the other end while introducing the second fluid at the sides of the exchanger to readily adapt said changer to both counter-flow and cross-flow operations.

Abstract: The disclosure describes wall for a direct fired heater which burns high sulfur fuels. The wall includes an inner casing lined internally with refractory and an outer casing spaced from the inner casing to provide, air space therebetween and means for controlling the rate of air flow thru the space. Proper selection of the refractory and proper control of the rate of air flow assure that the temperature of the inner casing is maintained above the dew points of sulfur oxides for any ambient condition. The casings are joined at their upper ends and an air opening is provided at the lower end of the outer casing whereby air is admitted to the air space. An adjustable air vent is provided at the upper end of the outer casing for control of casing temperature, when necessary. A plurality of horizontal baffles extend from the inner casing outward into the air space to inhibit re-circulation of air in the air space.

Abstract: A gas handling and cleaning system for the combustion gases of a coal-fired steam generator comprises an electrostatic precipitator which receives the combustion gases from the steam generator, a preheater downstream of the electrostatic precipitator and a wet scrubber intermediately positioned between the preheater and the stack. The temperature and humidity of the gases entering the stack are controlled by conveying regulated quantities of the gases from the exit of both the precipitator and the preheater to a location intermediate the scrubber and the stack.