Hera, LLC

Wahlco Environmental Systems, Inc.

Other

Wahlco, Inc.

Siirtec Nigi, S.p.a.

Wahlco Power Products, Inc.

Felix E Spokoyny

Henry V Krigmont

Vincenzo Lagana

Wayne R Kozacka

Everett L Coe, Jr

Vincent F Middleton

Po L Chien

Barry A Whyte

Michael K Hall

A safe, economical and predictable process for producing ammonia from a urea solution, preferably where only a small amount of ammonia is required, (i.e. for SCR denitrification for small boilers, flue gas conditioning to enhance precipitator efficiency and/or alleviate plume problems, SNCR and the like), using an ultrasonic processor to cause 'cold boiling' of portions of such solution and produce gaseous ammonia.

Method and apparatus for the production of gaseous ammonia from a urea solution

A method and apparatus for reducing the amount of unused ammonia (&ldquo;ammonia slip&rdquo;) in instances where ammonia is provided to SNCR and/or SCR processes for reducing NOx pollution in flue gas produced by a fossil fuel burning facility. Such a facility incorporates a rotary regenerative heat exchanger (i.e. an air preheater and/or a gas to gas preheater) for absorbing heat from the gas flow on one side of the heat exchanger, and releasing such absorbed heat to heat the gas flow on the other side of the heat exchanger. The invention herein includes absorbent/desorbent media carried by at least some of the elements of the heat exchanger. The media is active to adsorb at least a portion of the ammonia slip after NOx is treated, and before the gas flow is exhausted to the environment, and to desorb essentially an equilibrium portion of such adsorbed ammonia into gas flow upstream from the providing of ammonia for the SNCR/SCR process.

Method and apparatus for reducing &ldquo;ammonia slip&rdquo; in SCR and/or SNCR NOx removal applications

This invention relates to pollution control requirements for fossil fuel burning facilities such as power plants, and, more particularly, to an apparatus for providing a safe and economical supply of ammonia, from a urea feedstock, when ammonia is desired or necessary to initiate, cause and/or supplement the removal of one or more pollutants from an exhaust gas stream.

Apparatus for pollution control in exhaust gas streams from fossil fuel burning facilities

A method and apparatus for cleaning the catalytically active surfaces of selective catalytic reduction (SCR) substrate, and more particularly such a method and apparatus which: simultaneously generates two differing frequency sound waves which are effective in cleaning such surfaces, more effectively than if only single waves of such frequency were generated; utilizing spaced arrays of sound emitters at the entry and exit sides of selected SCR layers, with the emitters on opposite sides of the layers being in counter phase, or opposed synchronization; teaches design and placement of sound sources which optimize a variety of output cleanability predictions, for example pulsating pressure distribution, pulsating velocity distribution (U, V, W), time-averaged parameters and measure of cleanability.

Method for the in-situ cleaning of the catalytically active surfaces of SCR substrate

In many situations where the maximum NOx reduction capabilities of conventional SCR systems are not necessary, and alternative SNCR systems may not economically provide desired NOx reduction, a staged SCR/SNCR system is believed to be the most appropriate solution available. By means of the present invention, a system has been developed for delivering NOx reduction agents from a common urea feedstock, when it is appropriate to use combined NOx treatment stages (i.e. SNCR within the boiler followed by in-duct SCR and/or catalyzed air preheater elements). For the SNCR stage, the urea from the common feedstock is diluted prior to injection into the boiler and, for the SCR stage, the urea from the common feedstock is used to produce ammonia using hydrolysis. Urea solution which is not converted to ammonia in the hydrolyzer, is used for dilution of the solution being delivered to the SNCR system. Broadly, the invention herein is applicable to many instances in air pollution control wherein the facility in question requires both gaseous ammonia and urea solution to assist in the control of contaminants at discrete locations in one or more flue gas streams. In such instances the urea solution and gaseous ammonia will both use a common feedstock provided from a common urea source.

Pollution control systems using urea and ammonia for the control of emissions from the flue gas of fossil fuel burning facilities

A method and apparatus for reducing the amount of unused ammonia (&ldquo;ammonia slip&rdquo;) in instances where ammonia is provided to SNCR and/or SCR processes for reducing NOx pollution in flue gas produced by a fossil fuel burning facility. Such a facility incorporates a regenerative heat exchanger (i.e. an air preheater) for absorbing heat on the flue gas side, and releasing such absorbed heat to heat the incoming combustion air. The invention herein includes absorbent/desorbent media carried by at least some of the heat transfer elements of the heat exchanger. The media is active to adsorb at least a portion of the ammonia slip before the flue gas stream is exhausted to the environment, and to desorb essentially an equilibrium portion of such adsorbed ammonia into the incoming combustion air.

Method and apparatus for reducing &ldquo;ammonia slip&rdquo; in SCR and/or SNCR NOX removal applications

In many situations where the maximum NOx reduction capabilities of conventional SCR systems are not necessary, and alternative SNCR systems may not economically provide desired NOx reduction, a staged SCR/SNCR system is believed to be the most appropriate solution available. By means of the present invention, a system has been developed for delivering NOx reduction agents from a common urea feedstock, when it appropriate to use combined NOx treatment stages (i.e. SNCR within the boiler followed by in-duct SCR and/or catalyzed air preheater elements). For the SNCR stage, the urea from the common feedstock is diluted prior to injection into the boiler and, for the SCR stage, the urea from the common feedstock is used to produce ammonia using hydrolysis. Urea solution which is not converted to ammonia in the SCR phase, is used for dilution of the solution being delivered to the SNCR system.

Combined SCR/SNCR process

This invention relates to pollution control requirements for fossil-fuel burning facilities, such as power plants, and, more particularly, to a method for providing a safe and economical supply of ammonia, from a urea feedstock, when ammonia is desired or necessary to initiate, cause and/or supplement the removal of one or more pollutants from an exhaust gas stream.

Method and apparatus for pollution control in exhaust gas streams from

A method and apparatus for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes supporting a catalyst in the path of the flue gas, positioning temperature modifying means in communication with the catalyst, passing the flue gas by the catalyst and selectively varying the temperature of the catalyst, with the temperature modifying means, to vary the amount of catalytic conversion of SO.sub.2 in the flue gas to SO.sub.3.

Catalytic sulfur trioxide flue gas conditioning

An apparatus for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes: catalytically converting a portion of the sulfur dioxide contained within the flue gas to sulfur trioxide, by passing a portion of such flue gas through at least one catalyst containing converter module which is positioned within such a flue gas stream; and selectively varying the quantity of flue gas passing through such module by providing an aspirating force to cause flue gas to be drawn through such a converter module.

A method and apparatus for the selective control of the sulfur trioxide concentration in flue gases, to enhance the ash removal efficiency of electrostatic precipitators, which includes supporting a catalyst in the path of the flue gas, catalytically converting a portion of the sulfur dioxide contained within such flue gas to sulfur trioxide, by passing at portion of such flue gases over a catalyst which is positioned within the path; selectively varying the amount of sulfur trioxide produced by the catalytically converting, by selectively changing the quantity of flue gas flowing through such catalyst; and simultaneously maintaining the ratio of the pressure loss coefficient of the flue gas flowing through the other portion of such duct, in the vicinity of such catalyst, within a predetermined range.

A heat exchange module comprises a rotating-wheel type regenerative heat exchanger unit having a plurality of heat exchange elements mounted in baskets through the volume of the heat exchanger wheel. The heat exchanger wheel rotates about its axis so that the heat exchange elements are heated by a hot gas flow over a portion of the rotation, and transfer the heat to an air flow over another portion of the rotation. At least some of the heat exchange elements include phase change materials, such as salts, that absorb heat while maintaining a constant temperature. The phase change materials narrow the range of temperatures reached by the heat exchange elements located at various positions of the heat exchanger wheel. The phase change materials prevent excessively low temperatures that can result in condensation of corrosive acids on the surfaces of the heat exchange elements. They can also stabilize the heat exchange elements in particularly desirable temperature ranges for the operation of catalysts coated onto the heat exchange elements.

Temperature-stabilized heat exchanger

A sulfur trioxide conditioning system includes a catalytic converter that converts a portion of the sulfur dioxide in a flow of flue gas to sulfur trioxide. The catalytic converter includes a catalyst support, which is disposed across at least a portion of the cross section of a main duct from a burner to a heat recovery apparatus, and a catalyst on the catalyst support. The amount of the catalyzed surface exposed to the flow of flue gas is selectively varied to control the conversion of sulfur dioxide to sulfur trioxide.

A pack of heat transfer plates for regenerative heat exchangers is operationally adapted to absorb heat from a flue gas flowing in one axial direction along the main flow axis and release such heat to a combustion air flowing in another axial direction. The pack includes first and second mutually identical profiled plates which are arranged in mutually contiguous, contacting relationship with double ridges of the first plate intersecting double ridges of the second plate. The double ridges of the first and second plates extending symmetrically and obliquely in mutually opposite directions relative to the main flow axis of the heat exchange media flowing through the pack. The pack includes a third plate having provided thereon continuous extending parallel channel formers. One side of the third plate is in contiguous relationship with the second plate. The channel formers of the third plate define a second channel between the adjacent surfaces of the second and third plates in a manner that a substantially unobstructed flow of media, in both axial directions, may be established in the second channel. A plurality of the plate packs are arranged in baskets, and these baskets are located in various portions of the heat exchanger to achieve an optimum heat transfer and flow performance.

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Costa Mesa, CA, United States of America

Felix E Spokoyny