Classifications

• • 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
  • F23C10/002—Fluidised bed combustion apparatus for pulverulent solid fuel
• • 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
  • F23C10/18—Details; Accessories
  • F23C10/28—Control devices specially adapted for fluidised bed, combustion apparatus
  • F23C10/30—Control devices specially adapted for fluidised bed, combustion apparatus for controlling the level of the bed or the amount of material in the 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
  • C10J3/46—Gasification of granular or pulverulent flues in suspension
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L10/00—Use of additives to fuels or fires for particular purposes
  • C10L10/04—Use of additives to fuels or fires for particular purposes for minimising corrosion or incrustation
• • 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
  • F23G7/10—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses
• • 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
  • F23G7/10—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses
  • F23G7/105—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of field or garden waste or biomasses of wood waste
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2203/00—Furnace arrangements
  • F23G2203/50—Fluidised bed furnace
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2207/00—Control
  • F23G2207/10—Arrangement of sensing devices
  • F23G2207/107—Arrangement of sensing devices for halogen concentration
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2209/00—Specific waste
  • F23G2209/26—Biowaste
  • F23G2209/261—Woodwaste
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
  • F23J2215/00—Preventing emissions
  • F23J2215/30—Halogen; Compounds thereof

Definitions

• the invention relates to the utilization of undried logging residues and energy wood from thinning as well as green biomass in the production of energy and product gas, as well as the application of a fluidized bed process in this context.
• Combustion or gasification of fresh cut green biomass is more advantageous than before because energy production plants are now commonly equipped, in many cases in connection with investments in flue gas scrubbers, with apparatus for recovering the latent heat of water vapour contained in the flue gas (the energy needed for vaporization) by condensation, and for transferring a major part of it to, for example, a district heating network.
• This solution increases the degree of efficiency of the plant to a great extent, because the content of water bound in the fuel and being vaporized is high, in many cases higher than 50%.
• Halogens particularly in combination with alkali metals and in the presence of water vapour, tend to cause corrosion in boiler structures, for example on the surfaces of superheater pipes but also elsewhere, in metal structures as well as fire-resistant structures. They also cause soiling of the boiler by forming chemically and structurally complex deposits on the surfaces of metal structures, for example in heat exchangers. Thus, the heat transfer phenomena are substantially reduced, whereby the efficiency of the plant decreases.
• Halogens, sulphur, fine particulate matter and many other harmful substances can be efficiently removed by a flue gas scrubber, if one is in use.
• sulphur and halogen compounds have already done damage in the boiler materials, so that the flue gas scrubber is a solution merely for removing these substances from the flue gases to be released into the open air.
• various types of plants are used, such as grate, drum, fluidized bed, and stoker boilers.
• Fluidized bed reactors are used, for example, for combustion and gasification of solid or semi-solid organic material for producing energy or product gas.
• the application of fluidized bed technology has become more common as o a result of technological and economic benefits provided by it, and the development of the technology involved.
• several solid or semi-solid fuels such as peat, wood chips, cultivated plants, as well as various waste fractions, such as waste wood or sewage sludge, may be burnt or gasified simultaneously in a fluidized bed.
• the fuels may also have very different moisture and ash contents, as well as chemical compositions.
• the treatment in the fluidized bed may be combustion, for example, in a so-called circulating fluidized bed (CFB) or a bubbling fluidized bed (BFB), which are techniques requiring different apparatuses.
• CFB circulating fluidized bed
• BFB bubbling fluidized bed
• the fuels may have very different properties, the degree of combustion is good and the process is relatively smooth, because each solid particle to be burnt will be surrounded by combustion gas in the bed and be simultaneously heated to a temperature corresponding to pyrolysis.
• the fluidizing gas is low-oxygen or oxygen-free and contains, among other things, carbon dioxide, water vapour and nitrogen.
• the bed material to be fluidized is, in many cases, common sand rich in quartz, but it may also be different inorganic material with suitable particle size and other properties.
• the bed typically consists mostly of ash, while the rest of the bed material is also finer, having a particle size in the range of 0.1 to 0.3 mm.
• the typical particle size range is 1 to 3 mm.
• the solution according to the invention readily refinable material that is rich in calcium and/or magnesium is added, in a content of 30 to 100% of the amount of ash from fuel, to the bed material of the fluidized bed process, in order to bind the halogen and alkali components contained in the fuel directly or indirectly to the ash fraction being formed.
• the solution enables combustion of fresh undried wood material, particularly rich in chlorine and alkali, in a boiler having a high efficiency and simultaneously a reduced susceptibility to corrosion of the materials used, thereby improving the degree of utilization, the reliability, as well as the costs for repair and maintenance of the boiler to a substantial extent.
• conventional bed sand rich in quartz, is a hard and relatively inert material, but at temperatures typical for the bed, it reacts with fuel-based alkali metals, calcium and other substances, forming a partial smelt which is capable of sintering bed sand particles together so that after a sufficiently long exposure time they are no longer capable of fluidizing.
• the resulting alkaline earth halogenide and sulphate compounds are collected as solid ash particles on filters, from which they are removed together with other ash particles.
• the ash obtained is, at its best, an excellent fertilizer which can be utilized in separate processes. Linked to this is our previous patent application FI 20150289 .
• alkaline earth oxides are very good catalysts which are capable of catalysing pyrolysis and thereby make it possible to run the bed in a larger range of temperatures, which may bring various benefits, including benefits relating to environmental technology.
• alkaline earth oxides are capable of catalysing splitting of long-chain tar compounds to shorter chains, which may significantly boost the gasification process.
• the bed material used is a suitable material that is readily refined under bed conditions, forming a large reactive specific surface, and is capable of reacting efficiently with corrosive fuel-based components.
• Essential factors in the disintegration of the bed material particles are grinding, refining, chemical decomposition, and fragmentation as the temperature or volume are changed.
• the bed material has a high content of calcium and/or magnesium but a low content of alkali metals, silicon and aluminium.
• the bed material according to the invention does not, when supplied, differ significantly from conventional bed sand, rich in quartz.
• the readily refinable component of the bed material preferably comprises calcium carbonate (calcite) CaCO 3 , calcium magnesium carbonate (dolomite) CaMg(CO 3 ) 2 , or magnesium carbonate (magnesite) (Mg,Fe)CO 3 .
• the readily refinable component may also comprise waste material or a side product rich in CaO or MgO, such as incompletely calcined dolomite or calcite from lime burning kilns, fire-resistant dolomite or magnesite brick waste, steelmill ladle rich in calcium, converter or electric furnace slag, or sand from talcum production, rich in magnesite. Any of these materials may be combined to form readily refinable components which are capable of reacting efficiently with harmful substances, such as halogens and sulphur, contained in fuel.
• the bed material according to the invention is chemically decomposed in the bed according to the following reactions (oxidizing conditions): CaCO 3 ⁇ CaO + CO 2 CaMg(CO 3 ) 2 ⁇ CaO + MgO + 2CO 2 MgCO 3 ⁇ MgO + CO 2
• decomposition takes place in the surface part of the particle, but it preferably proceeds so that the whole particle is entirely decomposed thanks to simultaneous comminuting, whereby a fresh chemically undecomposed surface is exposed to chemical decomposition by the effect of heat, whereafter the surface may react with said corrosive harmful substances, for example as follows: MgO + Cl 2 ⁇ MgCl 2 + 1 ⁇ 2O 2 CaO + SO 3 ⁇ CaSO 4 CaO + F 2 ⁇ CaF 2 + 1 ⁇ 2O 2
• a particle which has not undergone complete degradation comprises an original inner part of e.g. a carbonate, and a surface part of the corresponding oxide which is reactive and capable of reacting with, inter alia, halogens, typically chlorine.
• the channels for feeding inorganic bed materials may include not only the actual system for feeding bed sand but also the system for feeding fuel. Furthermore, an extra channel may be used for supplying additives, particularly in some larger plants.
• Hard particles may be introduced in the bed so that their content in the bed does not exceed 50 wt-%. These may consist of quartz, conventional bed sand, olivine, corundum, granulated blast furnace slag, or any particles having a hardness value exceeding 4 on the Mohs scale.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Life Sciences & Earth Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Wood Science & Technology (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

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Cited By (4)

Citations (4)

• 2017
  • 2017-04-19 FI FI20177048A patent/FI20177048A/fi unknown
• 2018
  • 2018-04-19 EP EP18168199.0A patent/EP3392563A1/fr not_active Withdrawn

Patent Citations (4)

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