WO1998010037A1 - Procede et ensemble utilises pour accroitre la capacite d'une installation de chaudieres - Google Patents

Procede et ensemble utilises pour accroitre la capacite d'une installation de chaudieres Download PDF

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Publication number
WO1998010037A1
WO1998010037A1 PCT/FI1997/000518 FI9700518W WO9810037A1 WO 1998010037 A1 WO1998010037 A1 WO 1998010037A1 FI 9700518 W FI9700518 W FI 9700518W WO 9810037 A1 WO9810037 A1 WO 9810037A1
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WO
WIPO (PCT)
Prior art keywords
fuel
boiler
gas
air
furnace
Prior art date
Application number
PCT/FI1997/000518
Other languages
English (en)
Inventor
Jukka Hirvenoja
Original Assignee
Imatran Voima Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imatran Voima Oy filed Critical Imatran Voima Oy
Priority to AU41203/97A priority Critical patent/AU4120397A/en
Publication of WO1998010037A1 publication Critical patent/WO1998010037A1/fr
Priority to FI990402A priority patent/FI108251B/fi
Priority to SE9900653A priority patent/SE520040C2/sv

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/482—Gasifiers with stationary fluidised bed
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/72—Other features
    • C10J3/721—Multistage gasification, e.g. plural parallel or serial gasification stages
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/02—Dust removal
    • C10K1/026—Dust removal by centrifugal forces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C10/00—Fluidised bed combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/30—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having a fluidised bed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
    • F23G7/04—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste liquors, e.g. sulfite liquors
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2200/00—Details of gasification apparatus
    • C10J2200/15—Details of feeding means
    • C10J2200/152—Nozzles or lances for introducing gas, liquids or suspensions
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
    • C10J2300/0953—Gasifying agents
    • C10J2300/0956—Air or oxygen enriched air
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/12—Heating the gasifier
    • C10J2300/1223—Heating the gasifier by burners
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1603—Integration of gasification processes with another plant or parts within the plant with gas treatment
    • C10J2300/1621—Compression of synthesis gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1671—Integration of gasification processes with another plant or parts within the plant with the production of electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2201/00—Pretreatment
    • F23G2201/40—Gasification
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2206/00—Waste heat recuperation
    • F23G2206/20—Waste heat recuperation using the heat in association with another installation
    • F23G2206/203—Waste heat recuperation using the heat in association with another installation with a power/heat generating installation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/12—Heat utilisation in combustion or incineration of waste
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/14—Combined heat and power generation [CHP]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Definitions

  • the present invention relates to a method according to the preamble of claim 1 for increasing the capacity of a boiler plant in both energy production and as regards the capacity for processing fuel.
  • the invention is suited for, among other things, adding the proportion of electric power particularly in plants using fluidized-bed boilers, and for raising the capacity of soda recovery boilers.
  • the invention also relates to an assembly for carrying out the method.
  • One arrangement for combustion comprises a fluidized-bed boiler.
  • a fluidized-bed boiler typically solid fuel is fired in the furnace of the boiler in stages.
  • the conditions in the fluidized bed in the lower part of the furnace, where the fuel and inert bed material are intermixed and airborne by air jets from the bottom part of the boiler, are air-deficient, and thus, the fuel is not completely burnt in the fluidized bed, and instead, the volatile components are gasified.
  • the gasified fuel is then completely burnt by means of secondary and tertiary air fed above the fluidized bed.
  • the temperature of the fluidized bed is typically 700 to 900 degrees and the fuel is fed by dropping or by means of a pusher screw.
  • the fluidized bed is kept at fluidized state by means of a primary amount of air introduced from below the bed, this amount typically being about 40 % of the total amount fed into the boiler.
  • the remaining 60 % of air is introduced into the freeboard above the fluidized bed at a height which is typically about 4 to 8 m above the surface of the fluidized bed.
  • the fuel is gasified whereby volatile matter will rise to the freeboard where it is burnt by means of air inlet in steps.
  • Burning can in fluidized-bed boilers be divided into four zones in the following manner:
  • the fluidized bed is kept fluidized by blowing a sufficient amount of air through the bed by means of a grate.
  • the uppermost zone before the first heat exchangers penetrating the flue gas flow comprises a zone for burning up wherein the air ratio of the combustion is raised to a value above 1 and by means of the excess air, the gas and particles are burnt up.
  • the amount of fluidizing air in the furnaces of the boilers to a large extent corresponds to the amounts of air used in typical fluidized-bed carburettors, and thus, the composition of the gas above the surface of the fluidized bed and below the secondary air corresponds to gas produced in special carburettors, the caloric value of which is still relatively good when combusted. This is evident from a steep temperature rise after secondary air has been introduced.
  • the fluidizing medium circulates via the upper part of the boiler to a cyclone at the side of the furnace, in which the combustion gases and fluidizing medium are separated from each other.
  • the fluidizing medium is returned to the lower part of the boiler and the fuel used is fed into the returning inlet.
  • the gases are led into the convection part after separation of solid particles. Only the amount of gas required by the gas seal is admixed into the stream of particles returning to the furnace.
  • the mixture of fuel, fluidizing medium and circulating gas is very air-deficient, and accordingly, the fuel is strongly gasified before it ends up in the furnace.
  • the combustion air is introduced into the furnace in a similar manner as in the case of fluidized-bed boilers, that is, by blowing from the lower part of the furnace upwards and through inlets in the lower part of the furnace.
  • the phasing of the combustion air is almost exclusively the result of poor horizontal mixing in the furnace.
  • the fuel is admixed with air mainly in the vertical direction, and all mixing in the horizontal direction is slow wherefore there are strongly air-deficient areas in the vicinity of the fuel inlet points where the fuel is gasified and the burning up of the fuel is carried out while it moves upward in the furnace.
  • the phasing makes it possible to exhaust gas from the gasification zone of the furnace and use it for increasing the inlet temperature of a gas turbine by burning the exhausted gas in the combustion chamber of the gas turbine. Since the maximum temperature of the fluidized bed furnace is 900°C, the efficiency of the gas turbine would otherwise be poor because of the low temperature of the flue gases and the burning of the exhaus gases increases the efficiency notably by rising the inlet temperature.
  • This method is called "topping" and it is used chiefly in composite power stations. In this method the furnace has to be pressurized so that the flue gases and exhausted gas can be used in the gas turbine. Topping does not increase the maximum efficiency of the furnace and no extra fuel corresponding the combustion value of the exhausted gas can be fed into the furnace. Topping processes are described for example in EP 340 351 and WO 94/02711.
  • the phasing takes place in different steps in the flame of the burner by means of air currents led to the flame.
  • the fuel is usually fed from the center of a rotation symmetrical burner, and two air inlet channels are usually arranged around the fuel channel or nozzle. Close to the fuel inlet point, the flame is very air-deficient and reducing, and strong gasification occurs in the area.
  • the fuel is completely combusted by secondary and tertiary air led into the flame in stages.
  • additional air can be introduced into the upper part of the furnace, if need be.
  • black liquor is combusted by injecting it into the boiler at a suitable height.
  • the aim of the present invention is to achieve a method which can be used to raise the efficiency of a boiler with phased function, and in particular, the proportion of the electric power it produces can be increased.
  • the invention is based on the concept of exhausting gas from an air-deficient zone of the furnace by suction in phased burning, the gas being then separately combusted in a separate gas turbine or a separate boiler. An amount of additional fuel approximately corresponding to the amount of heat of gas exhausted by suction is then fed into the furnace or burner in order to compensate the heat volume removed from the furnace.
  • the invention offers considerable benefits.
  • the production capacity of an existing power plant can easily be increased, as well as its electricity production efficiency, as combustable gas formed during the initial burning stage of the fuel is removed from the furnace by suction such that it can be utilized for power production.
  • Combustible gas is always first formed during combustion, said gas being completely combusted given that a sufficient amount of oxygen is provided and the temperature is sufficiently high.
  • the maximum amount of gas exhausted depends on the fuel but is in an order corresponding to the amount of gas formed by the volatile components in the fuel.
  • the changes made in the previous process are small and mainly related to automation. More benefits can also be gained in the form of cheaper district heat power where the plant has a gas or an oil vessel for the combustion of the product gas.
  • the method is well suited for evening out the consumption peaks in small power plants because it will provide cheap additonal energy from the same vessel if need be, and there is no need to use expensive fuel in gaseous or liquid form.
  • the invention can be applied to many kinds of plants as long as the combustion takes place either in a boiler or a burner in sufficiently many phases.
  • the function of the system and, in particular, the gasification part of the system is balanced by the fact that the gasification process runs as a secondary line in a big and stable process and is therefore not as sensitive to failure as are small carburettors where the gasification process also needs to produce the heat required for gasification, whereby the quality of the gas produced is easily subject to compromising.
  • the heat required by gasification is obtained by means of the combustion process because heat is emitted from the zone for complete burning downstream into the fluidized bed, keeping up the gasification of the fuel.
  • Gas suction from the vessel does not reduce the efficiency of the vessel; instead, more fuel can be fed into the inlet area for primary air in the same vessel, i.e., a greater amount of fuel can be gasified, but only an amount of gas corresponding to that previously combusted is combusted in the upper part of the furnace. Additional efficiency obtained by gasification is limited by the temperature decrease in the fluidized bed and the fact that the suspension velocity or, in a soda recovery boiler, the amount of the lowermost air (primary air) can only be increased within certain limits so as not to disturb the function of the boiler. However, from a big boiler, significant additional fuel efficiency can be obtained which can be used to replace expensive gas turbine or boiler fuel. The increase in fuel efficiency can be as high as 20 to 30 %.
  • the purification and cooling of gas under atmospheric pressure emerging from the unpressurized boiler for compression is cheap, and thus, the cost of the additional equipment needed is reasonable.
  • the gas produced by a soda recovery unit can be used as fuel for the lime sludge reburning kiln, the superheating furnace gas turbine or an auxiliary boiler.
  • Fig. 1 illustrates one embodiment of the invention.
  • Fig. 2 illustrates a second embodiment of the invention.
  • Fig. 3 illustrates a third embodiment of the invention.
  • Fig. 4 illustrates a fourth embodiment of the invention.
  • Fig. 5 illustrates a fifth embodiment of the invention.
  • Fig. 6 illustrates a sixth embodiment of the invention.
  • the invention is based on exhausting gas by suction during combustion in phases from an area where the flame is strongly air-deficient and where gas is formed, the gas being further burnt by feeding air.
  • the gas is suctioned from an area in the furnace 24 of the boiler 1 where the quality of the gas is at its best.
  • the suctioned gas is purified and compressed to be under high pressure, such that it can be used as gas turbine fuel, for example.
  • an atmospheric-pressure carburettor is formed by very simple measures, and the efficiency of electricity production and fuel efficiency can be raised effectively also in old plants.
  • the invention can be implemented, e.g., in connection with fluidized-bed boilers.
  • Air nozzles 2 are provided in the lower part of the furnace 24 in a fluidized-bed boiler 1, air being blown upward from the nozzles into the fluidized bed 1 above the nozzles.
  • the fluidizing medium is usually sand.
  • the fuel is fed through inlets 4 and forms an airborne bed together with the fluidizing medium, the fuel and air being efficiently intermixed in the bed.
  • the velocity of the fluidizing air should be sufficiently low sow as to allow the fluidized bed to remain sufficiently shallow.
  • the fluidizing air is also primary air of the boiler 1, the proportion of primary air being about 40 % of the total amount of air in the boiler, and thus, the amount of air is insufficient for completely combusting the fuel. Due to efficient mixing, however, the fuel reacts well with the amount of air available and is effectively gasified. Gasification efficiency is increased by heat emitted from the top part of the boiler.
  • a splash area 9 is provided upstream of the fluidized bed 3, injections of fluidizing medium and ungasified fuel particles rising into the splash area. No additional area is introduced into this area, and therefore, only the fuel will react with the rest of the free oxygen.
  • the actual combustion of gasified fuel takes place further up in the boiler.
  • additional air is fed into the boiler through secondary air inlets 5, whereb the gasified fuel is ignited and the temperature in this bed reaches the range from 800 to 1400 °C.
  • Secondary air i fed in an amount causing the total air ratio to rise to a value close to 1, and accordingly, air is almost completel combusted in this bed.
  • the rest of the air is fed into a zone 11 for complete combustion through tertiary air inlet 6, whereby combustion of all of the remaining gases and particles is aimed at in said zone.
  • combustion gases rise into the top part of boiler 1 provided with the first heat exchangers usually comprising steam circuit superheaters 7. From the superheaters 7 the combustion gases are brought to heat exchangers 8 in the convection channel and from there, further to purification and a chimney.
  • Gas used as fuel in a gas turbine or a separate boiler is exhausted from the boiler 1 via outlets 12 arranged above the fluidized bed.
  • the outlets can be positioned in various ways but the gas must be exhausted evenly from the boiler so as not to disturb the streams in the furnace 24 too much.
  • the suction nozzles are preferably positioned evenly around the walls of the boiler similarly to the positioning of the air infeed nozzles.
  • the suction nozzles 12 for gas In order to obtain the desired gas from the furnace 24 and in order not to suction the completely combusted gas from further up in the furnace, the combustion of which is no longer possible, the suction nozzles 12 for gas must be positioned below the secondary air infeed nozzles 5.
  • the suctioned gas contains impurities and fluidizing medium which cannot be allowed to enter, e.g., a gas turbine.
  • the gas is purified in a manner known per se whereby the first purification step in at least a fluidized-bed boiler preferably comprises a cyclone 14 or other apparatus capable of separating rough particles.
  • the impurities in particle form separated from the cyclone 13 as well as the fluidizing medium are led back to the fluidized bed 3 through an inlet 14.
  • the purification result is finished off by means of a washer 16 to which the gas is led along the line 15 or else, it is led to heat-proof filters.
  • the advantage with a washer 16 lies therein that in it gas can be cooled at the same time.
  • the gas is led into a compressor along line 17, wherein the gas is compressed to service pressure, and the product gas is led to combustion along line 20 or is utilized is another manner. If the gas is combusted in the auxiliary combustion boiler, cyclone separation may alone suffice as purification and compression is not necessarily needed.
  • the compressor 18 is rotated by means of a separate motor 19 or the compressor may be the compressor of the gas turbine, if the product gas is led directly into the turbine suction air.
  • the cyclone 21 is located in the fluidized bed 3 inside the furnace 24. Gas is suctioned into the cyclone 21 through duct 22 and the airborne material and solid particles are removed and conducted back to the bed via duct 23.
  • the equipment corresponds to the above description.
  • Fig. 3 illustrates a circulating fluidized-bed boiler 25.
  • combustion air is blown from the bottom of the boiler 25 upwards by means of inlets 27 at the bottom and by secondary air inlets 26 in the lower part of the furnace 24.
  • the air flow rate in the furnace is kept so high that the fluidizing medium will rise to the upper part of the furnace where it is transferred into the cyclone 32 together with the combustion gases.
  • the fluidizing medium is separated from the combustion gases which are taken to the convection part 35 which is equipped with heat exchangers 8 in the conventional manner.
  • the fluidizing medium falls into the lower part of the cyclone 32 from where it is fed back to the lower part of the furnace 24 and into the zone of the air inlets 26.
  • Fuel is fed into the boiler via a separate fuel feeder 29 directly into the zone of the air inlets 26 or into the reflux channel 34 for fluidizing medium.
  • the gases emerging from the cyclone together with the fluidizing medium comprise completely burned combustion gases and air needed for the aeration of the gasification, the amount of which is so small that the small fuel particles having entered with the fluidizing medium consum a large part of the oxygen derived therefrom, a very small amount of oxygen is admixed with the fuel fed into the reflux channel 34 before it is led into the furnace 24.
  • the mixture of fuel, fluidizing medium and circulating gas is highly air-deficient, and accordingly, before ending up in the furnace 24, the fuel is strongly gasified due to the heat of the fluidizing medium and the hot combustion gases.
  • the phasing of fuel fed directly into the furnace 24 takes place close to the feed point for fuel.
  • gasified fuel can be removed by suction from the immediate vicinity of the feed nozzles 29 in a similar manner as from the fluidizing medium reflux channel 34.
  • Gas formed by the fuel can be removed from the reducing area 41 of the flame by suction in a similar manner as from fluidized-bed boilers.
  • a suction pipe 40 is placed near the burner tip such that it reaches the gasification area 41.
  • Suction pipes can be placed in all burners in a boiler, or in just some burners.
  • a soda recovery boiler is shown.
  • the upper part of the boiler with heat exchangers corresponds approximately to the upper part of a fluidized-bed boiler or a pulverized fuel boiler with their superheaters 7 and convection parts 35.
  • the black liquor used as fuel in the soda recovery boiler is injected into the furnace 24 via inlet nozzles 45 positioned around the furnace.
  • the fuel drops are dried and burnt while falling and all unburnt matter is gathered on the boiler bottom and forms a hill 48. Green liquor is removed from the edges of the hill 48 via outlets 49 and is the returned to the pulping process.
  • Air is fed into the furnace in three phases through inlets 44, 46 and 47.
  • the mixture of black liquor and air is extremely air-deficient, wherefore black liquor is merely gasified in this area.
  • combustible gas can be suctioned from the furnace below the lowermost air inlets 47 or approximately at said inlets. Gas is suctioned through duct 50 which is cleaned for use by means of a cleaner 51.
  • the liquor processing capacity of an expensive boiler investment can be increased in a most economical manner. Soda recovery boilers being extremely expensive, they are dimensioned as small as possible, and there is clear need for additional capacity.
  • the heat value of the gas obtained by above described methods is relatively low since it contains plenty of inert components such as nitrogen and water.
  • the heat value of the gas can be increased by decreasing the amount of nitrogen and/or water in the gas.
  • the gas is enriched by decreasing its nitrogen content. This is accomplished by dividing the furnace partially by a wall 52 in two spaces and feeding extra fuel into one of the spaces. The space wherein the extra fuel is fed is smaller than the rest of the furnace space, whereby less air comes from the bed into this space. Since the amount of air in relation to the fuel is smaller in the space wherin the extra fuel is fed, the heat value of the gas in this space is greater than that of the gas in the neighbouring space.
  • the amount of air that comes from the bed in the separated spaces of the furnace can be determined by the areas (x, y) occupied by the spaces over the bed 3.
  • the gasified excess fuel is removed from the furnace as high as possible because the flames in the main combustion zone above radiates energy downwards and also some clusters of bed material travel high in the furnace.
  • the energy from the main combustion zone increases the energy of the top part of the smaller gasification space and facilitates the decomposition of tars of the fuel.
  • the present invention has other embodiments, too.
  • the suctioned product gas can be burnt in an auxiliary boiler, a lime sludge reburning kiln or other boiler where the additional energy obtained by burning gas is needed.
  • One way of utilizing the gas could be cementation performed within the mechanical engineering industry and the steel industry.
  • steel is subjected, at an elevated temperature, to a reducing gas containing a lot of carbon monoxide, whereby coal is diffused on the surface of the steel, the coal considerably increasing the hardness of the steel during quick cooling of the steel by a martensite reaction.
  • the cementation furnace would be placed right next to the cyclone in the line, whereby the cyclone may first be followed by normal combustion or purification and compression into a high pressure.
  • the method could be implemented to reduce fuel costs within the mechanical engineering industry.
  • the method according to the invention is particularly well suited for old boilers but can also be advantageously exploited in new boilers whereby greater than usual efficiency is achieved with a boiler of a certain size.
  • the parts relating to the use of gas and to the combustion of solid material can naturally be selected more freely in new boilers than in already existing boilers because the assembly can be designed to function in a certain manner from the outset.
  • the method can be implemented in connection with an additional or an initiation burner and for damp fuel, if the fuel is dried before combustion so as to improve gas quality.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Fluidized-Bed Combustion And Resonant Combustion (AREA)

Abstract

L'invention se rapporte à un procédé servant à accroître la capacité d'une installation de chaudières, en ce qui concerne aussi bien la production d'énergie que le volume de traitement combustible. L'invention sert notamment à augmenter la part d'énergie électrique, particulièrement dans des installations utilisant des chaudières à lit fluidisé et à accroître la capacité de chaudières de récupération de soude. L'invention consiste à évacuer le gaz par succion à partir d'une zone pauvre en air en combustion graduelle, par exemple à partir du lit fluidisé d'une chaudière à lit fluidisé. Le gaz est ensuite soumis séparément à une combustion dans une turbine à gaz ou dans une chaudière distincte. Une certaine quantité de combustible additionnel correspondant approximativement à la quantité de gaz évacué peut alors être amenée dans la chaudière ou le brûleur.
PCT/FI1997/000518 1996-09-04 1997-09-04 Procede et ensemble utilises pour accroitre la capacite d'une installation de chaudieres WO1998010037A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU41203/97A AU4120397A (en) 1996-09-04 1997-09-04 Method and assembly for increasing the capacity of a boiler plant
FI990402A FI108251B (fi) 1996-09-04 1999-02-24 Menetelmä ja sovitelma kattilalaitoksen kapasiteetin nostamiseksi
SE9900653A SE520040C2 (sv) 1996-09-04 1999-02-24 Förfarande och anordning för att öka kapaciteten hos en pannanläggning

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI963459 1996-09-04
FI963459A FI963459A0 (fi) 1996-09-04 1996-09-04 Foerfarande och anordning foer oekning av kapasiteten hos en pannanlaeggning

Publications (1)

Publication Number Publication Date
WO1998010037A1 true WO1998010037A1 (fr) 1998-03-12

Family

ID=8546600

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1997/000518 WO1998010037A1 (fr) 1996-09-04 1997-09-04 Procede et ensemble utilises pour accroitre la capacite d'une installation de chaudieres

Country Status (4)

Country Link
AU (1) AU4120397A (fr)
FI (1) FI963459A0 (fr)
SE (1) SE520040C2 (fr)
WO (1) WO1998010037A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010057717A1 (fr) * 2008-11-20 2010-05-27 Biomass Heating Solutions Limited Système anti-dépôt de cendres

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4682985A (en) * 1983-04-21 1987-07-28 Rockwell International Corporation Gasification of black liquor
EP0340351A1 (fr) * 1988-05-03 1989-11-08 Foster Wheeler Energy Corporation Procédé de production de gaz actionnant une turbine à gaz
WO1994002711A1 (fr) * 1992-07-24 1994-02-03 Veag Vereinigte Energiewerke Ag Procede et dispositif d'exploitation d'une centrale electrique hybride
US5486269A (en) * 1991-11-04 1996-01-23 Chemrec Aktiebolag Gasification of carbonaceous material in a reactor having a gasification zone and a combustion zone

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4682985A (en) * 1983-04-21 1987-07-28 Rockwell International Corporation Gasification of black liquor
EP0340351A1 (fr) * 1988-05-03 1989-11-08 Foster Wheeler Energy Corporation Procédé de production de gaz actionnant une turbine à gaz
US5486269A (en) * 1991-11-04 1996-01-23 Chemrec Aktiebolag Gasification of carbonaceous material in a reactor having a gasification zone and a combustion zone
WO1994002711A1 (fr) * 1992-07-24 1994-02-03 Veag Vereinigte Energiewerke Ag Procede et dispositif d'exploitation d'une centrale electrique hybride

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010057717A1 (fr) * 2008-11-20 2010-05-27 Biomass Heating Solutions Limited Système anti-dépôt de cendres
US8819987B2 (en) 2008-11-20 2014-09-02 Biomass Heating Solutions Limited Mushroom production process
US8919289B2 (en) 2008-11-20 2014-12-30 Biomass Heating Solutions Limited Poultry rearing process

Also Published As

Publication number Publication date
SE9900653D0 (sv) 1999-02-24
FI963459A0 (fi) 1996-09-04
AU4120397A (en) 1998-03-26
SE520040C2 (sv) 2003-05-13
SE9900653L (sv) 1999-04-30

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