A. Ahlstrom Corporation

A. Ahlstrom Osakeyhtio

Foster Wheeler Energia Oy

Pyropower Corporation

Folke Engstrom

Juhani M Isaksson

Reijo J Kuivalainen

Ragnar G Lundqvist

Seppo Kalervo Ruottu

Kaj Henricson

Erkki J Kiiskila

Jorma J Nieminen

Yam Y Lee

Karukkampalayam M Sellakumar

Mikko Hupa

Bertel K Hakulin

Charles M Davis

Pekka Tormikoski

Asfaha Tesfai

Juha P Sarkki

John T Tang

Reijo Kuivalaninen

Juha Tiensuu

Juha Sarkki

In the filtering of high temperature (e.g. greater than 400.degree. C.) and high pressure (e.g. greater than 5 bar) gas--such as produced by pressurized fluidized bed combustion or gasification of coal--there is often a buildup of particles on the supporting elements for the filters, and on surrounding structures. This buildup of particles can damage the filter elements, or greatly reduce their effectiveness. This problem is avoided by periodically automatically cleaning the supporting and/or surrounding surfaces of the filters, as by directing high pressure gas streams at the supporting and/or surrounding surfaces. The filters may also be backflushed with compressed gas, as is conventional, at the same time as, or at different times than, when the supporting and/or surrounding structures are cleaned. Conduits with nozzles may be mounted directly on the supporting and/or surrounding surfaces and connected by a pipe with an automatically controlled valve to a source of high pressure fluid.

Eliminating ash bridging in ceramic filters

Apparatus for cleaning high temperature, high pressure gases includes a pressure vessel, and a filtration unit within the pressure vessel. The filtration unit is adapted to communicate with a fluidized bed reactor gas outlet, and includes at least one dirty gas chamber housing a plurality of porous, ceramic filter tubes, and at least one clean gas chamber for receiving clean gas from the ceramic filter tubes. The dirty gas chamber includes a particle outlet for removing particles separated from the gas by the filter tubes. The porous ceramic filter tubes are horizontally oriented within the filtration unit or housing and mounted within water cooled walls of the housing. The fluidized bed reactor and associated cyclone separator may be located within the pressure vessel with the filtration unit, or located outside the pressure vessel and in communication with the filtration unit inside the pressure vessel.

Cleaning of high temperature high pressure (HTHP) gases

The amount of N.sub.2 O in flue gases discharged from a fluidized bed combustion system is minimized by adding an N.sub.2 O decomposing catalyst in a reactor stage downstream of the combustor. The catalyst preferably is a calcium based sorbent, such as CaO or or limestone, although NiO and other catalysts also may be utilized. Typically, the N.sub.2 O decomposition takes place without increasing the temperature of the flue gases above the 700.degree.-1000.degree. C. level that exists combustor. However, under some circumstances, if a second fluidized bed is provided as the reactor stage, additional fuel and oxygen can be added to increase the temperature of the flue gases to insure that it is over 800.degree. C. After N.sub.2 O decomposition, the flue gases may be passed through pressurized filter tubes, or through a superheater, economizer, air preheater, optional cyclone separator, and baghouse filter. A cyclone separator is preferably provided between the combustor and reactor stage, and the removed particles are recirculated to the combustor. Removal of particles, including unused sorbent, after the reactor stage also preferably takes place, with recycle to the reactor stage (if a fluidized bed stage) and/or to the combustor.

Method for reducing emissions when burning nitrogen containing fuels

The amount of N.sub.2 O in flue gases discharged from a fluidized bed combustion system is minimized by effecting vigorous and intimate mixing of the flue gases (with entrained particles) from a fluidized bed by increasing the velocity of the flue gases and then decreasing the velocity from the increased level, introducing a N.sub.2 O decomposing catalyst into the flue gases and particles immediately after increasing and decreasing of the velocity, and mixing the N.sub.2 O catalyst with the flue gases and particles, to effect decomposition of the N.sub.2 O. The catalyst is a calcium based sorbent, such as CaO or limestone, although and other catalysts also may be utilized. Normally the decomposition takes place without increasing the temperature of the flue gases. The increase in velocity is achieved by providing a constriction in the combustor vessel. The interior of the combustor vessel is lined with erosion resistant and thermal insulating material. Where the catalyst is calcium based sorbent, it is calcined, and the calcined particles are removed from the flue gases and recirculated to the fluidized bed, providing at least about 10 to 30% of the calcium based sulfur absorbing sorbent necessary to remove sulfur from the flue gases.

Reducing Z.sub.20 emissions

A filter assembly for high temperature gases, such as from a circulating fluidized bed reactor, mounts monolithic ceramic filter elements within an upright vessel so that as the hot gas flows from the top toward the bottom of the vessel the gas passes through the elements with the clean gas discharged through a side wall of the vessel. The particle discharge is provided at the bottom of the vessel. Filter supporting elements within the vessel are cooled by cooling fluid, and pulse cleaning elements are associated with each of the filter elements. Flow directing elements within the vessel typically define a generally conical or pyramidal shaped flow directing surface. The flow directing elements may be refractory material bodies, or funnel shaped thin elements (e.g. of metal capable of withstanding high temperature), and may be mounted so that small amounts of movement are possible to accommodate thermal contraction or expansion.

Cylindrical filters in a tube sheet for cleaning high temperature gases

A fluidized bed reactor uses fluid conduits for supplying fluids (such as liquid, gaseous, or fine solid material in suspension fuels), into a reactor chamber. The fluid conduits extend horizontally from, and substantially perpendicularly to, a side wall into the reactor chamber. The fluid conduits are disposed at a level (e.g. about 100-1000 mm) above the fluidizing gas nozzles in the bottom of the reactor chamber. An upright partition, preferably of refractory material, covers the fluid conduits.

Fluidized bed reactor with protected fluid distributor

A pressurized boiler assembly (e.g. with a circulating fluidized bed combustion chamber), including a pressure vessel pressurized to about 7-30 bar, has a minimum height, minimum number of through extending openings in the pressure vessel, and maximum accessibility to the controls and adjustments for the boiler. A steam drum is mounted by a flange joint above the boiler so that it extends horizontally, with the main body of the steam drum with the pressure vessel, but with a first end of the steam drum exteriorly of the vessel. The control and adjustment elements for the boiler, such as safety valves, pressure indicators, and water gauges, are mounted to the first end of the steam drum, exteriorly of the pressure vessel. A superheater having a discharge conduit is also mounted within the vessel below the steam drum, and the first end of the steam drum and the superheater discharge conduit are essentially the only elements associated with the boiler water and steam system passing through the pressure vessel.

Pressurized boiler plant

Fluidized bed reactor method and apparatus for removal of coarse material from the reactor. The apparatus comprises a discharge device including a substantially vertical pipe portion connected at one end with an outlet opening in the reactor grid, and at another end to an aeration chamber containing a discharge opening located below the level of the grid outlet opening; and a device for supplying pressurized air in short blasts of 30 to 100 milliseconds, preferably at pressures of from 2.5 to 7.0 bar, into the aeration chamber in the direction of the discharge opening to remove the coarse material from the reactor. Low pressure fluidizing air may be supplied to the vertical pipe portion as well as the aeration chamber to return small particles in the discharge device to the fluidization zone of the reactor.

Fluidized bed reactor method and apparatus

A circulating fluidized bed reactor comprises a separator including a vortex chamber adjacent the top of the reactor for separating solid material from the flue gases of the reactor. A channel directs flue gases discharged from the reactor and adjacent the top of the reactor in a downward direction. A main portion of the solid material is separated from the gases by a change of flow direction after which the solid material is returned to the lower part of the reactor. The main portion of the gases is directed, after the change of direction, to the vortex chamber where further separation of solid material is effected and the separated solid material is returned to the reactor.

Circulating fluidized bed reactor and a method of separating solid

A circulating fluidized bed reactor having a reactor chamber for containing fluidizing gas having entrained therein particulate material; a horizontal cyclone having a circumferential wall defining a separator chamber operatively connected at the reactor chamber for separating the material from the gas; a return pipe connected at the separator chamber of the cyclone at the circumference thereof for returning the separated material from the separator chamber to the reactor; and means for discharging the purified gas located in at least one end of the separator chamber of the cyclone. Preferably the separator chamber is located above the reactor chamber and the return pipe is connected at the lowermost point of the circumference of the separator chamber. The reactor is useful as combustor, gasifier and for the carrying out of chemical process.

Fluidized bed reactor

A circulating fluidized bed reactor includes a filter apparatus for separation and recycling of fine particles which are entrained by the flue gas. The housing of the filter apparatus has a plurality of vertically disposed ceramic filtration tubes. The reactor chamber and filter housing are arranged back-to-back and have a common wall therebetween. A pre-separator for separation of coarse particles is provided which connects the reactor chamber with the filter apparatus. The reactor, the separator and the filter apparatus are encased in a pressure-proof cylindrical vessel. The walls of the reactor chamber and the filter housing can be water-cooled. In another form, the filter is comprised of a plurality of porous plates having ribs abutting adjacent plates to define passageways through the filter.

Circulating fluidized bed reactor

A fluidized bed reactor (1) comprising a reactor chamber (4) having a gas distributor plate (5) for feeding primary air, and space above said distributor plate (5) is divided into compartments (6) by means of partition walls (7) having discharge openings (9) for feeding secondary air to the circulating bed.

In a fluidized bed reactor, nozzles are provided for distributing fluidizing gas from a windbox into the reactor while preventing the backflow of solid particles through the nozzle into the windbox. The nozzle defines an upper part of high heat and wear resistant material adapted to contact the mass of particles. At least one opening is defined in each nozzle through which fluidizing gas passes between the upper part and the windbox, and a solid, though porous, material abuts or defines the opening for allowing the passage of gas while preventing passage of solid particles. The nozzle may comprise a stand pipe having a sintered metal portion disposed below the upper part. Other constructions provide the solid mass as a metal wire mesh acid proof filter, or as a porous ceramic material, or as a high temperature ceramic material. The solid mass may have pores with a pore size of between about 50-1,000 micormeters. The solid mass may be defined by a pair of concentric adjacent porous ceramic tubes with different effective gas permeabilities. A horizontal solid metal ring may have openings in it, with the ring supported above the windbox so that gas can flow through the openings, the porous solid material sandwiched between the upper part and the ring.

Distributor plate for fluidized bed reactor

The system includes a circulating fluidized bed combustor coupled at its outlet to a separator. A vertical return channel is provided for conveying separated solid particles from the separator back to the combustion chamber. A gas turbine cycle is provided, including a gas compressor, a heat transfer means directed to a first duct to the compressor for heating the compressed oxidizing gas, a gas turbine connected through a second duct to the heat transfer means for power generation and a third duct for conveying expanded oxidizing gas from the turbine to the combustion chamber. The heat transfer means includes tubes disposed inside the vertical return channel for indirect heat transfer between the compressed gas and the dense suspension of separated particles flowing downwardly in the vertical channel.

Integrated gas turbine power generation system and process

Solids are separated from the flue gases of a fluidized bed reactor with a circulating bed and provided with cooling surfaces and are recycled to the reactor through return ducts disposed at different heights in the reactor. To control the operation of the reactor the heat removed from the reactor chamber is regulated by changing the suspension density in the reactor chamber. A required suspension density is obtained by regulating the flow of the solids through each return duct.

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San Diego, CA, United States of America

Folke Engstrom