Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B47/00—Destructive distillation of solid carbonaceous materials with indirect heating, e.g. by external combustion
  • C10B47/18—Destructive distillation of solid carbonaceous materials with indirect heating, e.g. by external combustion with moving charge
  • C10B47/22—Destructive distillation of solid carbonaceous materials with indirect heating, e.g. by external combustion with moving charge in dispersed form
  • C10B47/24—Destructive distillation of solid carbonaceous materials with indirect heating, e.g. by external combustion with moving charge in dispersed form according to the "fluidised bed" technique
• • 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
  • F23C10/005—Fluidised bed combustion apparatus comprising two or more beds

Definitions

• the invention relates to a method and a system for the degassing or partial degassing of solid fuel in a reactor, the heat energy required for degassing or partial degassing being generated in a furnace.
• a so-called reduction zone downstream of the main combustion zone into which a reducing agent, preferably a reducing gas, is introduced to reduce the nitrogen oxides formed in the main combustion zone.
• the required reducing gas can also be obtained by removing or gasifying a corresponding amount of fuel diverted from the primary fuel (DE-OS 34 13 564). This means that - when using additional energies and substances, e.g. Natural gas relatively high - supply costs for the reducing agent can be reduced.
• a further reduction in nitrogen oxide emissions is achieved if the entire solid fuel is degassed or partially degassed before it is burned (DE-OS 36 14 497), parts of the released volatile constituents in turn being able to be used directly as reducing agents.
• the solid fuel has a favorable influence on the combustion chamber temperature and thus reduces the nitrogen oxide concentration in the main firing zone, with only the residual nitrogen remaining in the degassed or partially degassed solid fuel reaching the main firing zone and leading to a lesser extent to nitrogen oxide formation.
• the lower nitrogen oxide formation in the main firing zone has a particularly advantageous effect on the total nitrogen oxide emission, since, according to the current state of knowledge, a relative proportion of the nitrogen oxide formed in the main firing zone is reduced in the reduction zone.
• DE-OS 36 14 497 it is further proposed that the degassing device for the solid fuel directly in the flue gas stream of a large combustion plant, e.g. of a power plant boiler, to be arranged and thus to decouple the thermal energy required for degassing the solid fuel from the flue gas of the large combustion plant.
• a large combustion plant e.g. of a power plant boiler
• the present invention is therefore based on the object of specifying a simple and economical method for degassing a solid fuel and a system which is suitable for carrying out the method and which in particular also operates largely independently of the respective operating state, for example of a combustion system, under optimal conditions for degassing the solid fuel can be.
• This object is achieved according to the invention in a process of the type mentioned at the outset in that the required thermal energy is transferred into the degassing reactor by indirect heat exchange via at least one common separating surface between the degassing reactor and the hot gas heat exchanger, and in that the reactor and hot gas heat exchanger are operated as separate fluidized beds become.
• the feature of the invention is accordingly the combination of a fluidized bed degassing with a hot gas fluidized bed heat exchanger and material separation of the two fluidized bed spaces by at least one, preferably a plurality of parallel heat-transferring partition walls with the advantage of heat transfer of fluidized beds acting on both sides of the partition wall, both fluidized beds being largely independent of the respective operating conditions of other systems, e.g. a furnace can be operated.
• the fluidized bed of the degassing reactor is expediently operated at a lower fluidizing speed than the fluidized bed of the hot gas heat exchanger. This results overall in a lower fluid flow and a lower fluidized bed requirement.
• recirculated gas obtained therein, after solids separation, cooling and pressure increase, is used as the fluidizing agent for the fluidized bed of the degassing reactor.
• any hot gas that is available can be supplied to the hot gas fluidized bed heat exchanger, regardless of the operation of a combustion system, as a heat carrier.
• part of its hot flue gas is expediently the Wir Sheet of the hot gas heat exchanger as a heat transfer medium and fluidizing agent.
• Suitable bed material for the fluidized bed of the hot gas heat exchanger is fine-grained, good heat-conducting material, preferably sand and / or fly ash.
• hot gas heat exchanger is operated as an independent fluidized bed furnace, it is expedient to use degassed fuel from the degassing reactor as fuel for the fluidized bed furnace.
• the degassed fuel required in the fluidized bed furnace can be used immediately, e.g. mechanically, are conveyed from the degassing reactor into the fluidized bed furnace. According to a further feature of the invention, however, the fuel input from the degassing reactor into the fluidized bed furnace is expediently carried out pneumatically, a mixture of an inert gas and an oxygen carrier being used as the fluid gas.
• degassed solid fuel including fluidized bed combustion
• nitrogen oxide emissions can largely reduce nitrogen oxide emissions here as well.
• the proportion of inert gas to the oxygen carrier or its oxygen content can be used to adapt the proportion of oxygen contained in the inert gas-oxygen mixture to the oxygen requirement of the fluidized bed furnace, thereby regulating both its heat output and the required fluid flow.
• Recycled flue gas from the fluidized bed furnace is expediently used as the inert gas.
• the fluidized bed combustion is expediently operated with an inert bed material, the grain size of which is larger than the grain size of the degassed solid material.
• the traveling speed of the burning solid particles in the fluidized bed furnace is delayed and, overall, a better temperature distribution over the length of the fluidized bed furnace and a better heat transfer are achieved.
• a plant for performing the method is characterized in that the hot gas heat exchanger or the fluidized bed furnace is arranged within the degassing reactor, its or its walls being made of a material which is a good heat conductor. Both fluidized beds of the hot gas heat exchanger or the fluidized bed combustion and the degassing reactor have their own supply and removal systems.
• the fluidized bed space of the ice gas heat exchanger or the fluidized bed furnace is expediently divided into a plurality of swirl chambers which can be jointly supplied and disposed of, each with its own partition walls for material delimitation within the degassing reactor.
• a plant with a fluidized bed arranged inside the degassing reactor and consisting of one or more vertical chambers arranged parallel to one another Firing is characterized in that the chambers are immersed in the fluidized bed of the degassing reactor up to the top of the nozzle and that injector nozzles for introducing an inert gas-oxygen mixture together with degassed fuel from the degassing reactor are arranged below the chambers in the fluidized bed combustion chambers, the The degassing reactor is charged with fresh fuel to be degassed in the area of the fluidized bed surface.
• the degassing reactor is charged from below, and the degassed fuel is drawn off in the region of the bed surface, and part of the degassed fuel is fed into the chamber or the chambers of the fluidized bed combustion via one or more return channels promoted.
• Injector nozzles for the pneumatic metering and delivery of the degassed fuel into the chamber or chambers of the fluidized bed furnace are provided before the return channel or ducts open into the chamber or chambers of the fluidized bed furnace.
• the method and the system according to the invention are preferably used to degas the solid fuel required for a combustion system, for example a dust generator for a steam generator, while at the same time a part of the gas obtained in the degassing reactor is fed to the reduction zone downstream of the main combustion zone as the reduction gas.
• Degassed solid fuel and reducing gas are fed into the combustion system with the least possible cooling.
• the fluidized beds of both the hot gas heat exchanger or the fluidized bed furnace and the degassing reactor can be operated at a slight excess pressure, for example 100 mbar, above the combustion chamber pressure.
• the excess gas obtained in the degassing reactor can be withdrawn from the plant and used for other purposes.
• the process according to the invention and the installation according to the invention can in principle be integrated into a combined process, the gas obtained in the degassing reactor or the excess gas being fed to a gas turbine combustion chamber.
• the fluidized beds must be run with a higher overpressure which is adapted to the operating conditions of the gas turbine.
• FIGS. 5, 6 schematically show possible embodiments of a plant according to the invention with a fluidized bed furnace arranged in the degassing reactor.
• a particularly uniform temperature distribution over the cross section of the degassing reactor 1 is achieved if, according to the example shown in FIG. 1, the hot gas heat exchanger or the fluidized bed furnace 2 is designed as a tube system, the individual tubes 2a being arranged at uniform intervals from one another.
• the hot gas heat exchanger or the fluidized bed furnace 2 is designed as a tube system, the individual tubes 2a being arranged at uniform intervals from one another.
• FIG. 2 divides the hot gas heat exchanger or the fluidized bed stratified combustion 2 into a plurality of swirl chambers 2a with parallel chamber walls 3, which are arranged next to one another at intervals.
• FIGS. 3 and 4 show further possibilities for arranging the hot gas heat exchanger or the fluidized bed furnace 2 and the degassing reactor 1, which are separated by a partition 3 made of heat-conducting material, which in the example of FIG. 4 additionally has heat-conducting sheets 5.
• the solid fuel to be degassed is introduced into the fluidized bed 12 of the degassing reactor 1 via a fuel feed 11.
• Degassed fuel is drawn off via a line 13 and burned, for example, in a large combustion plant.
• the thermal energy required for degassing the solid fuel is generated in the fluidized bed furnace 2 arranged within the degassing reactor 1 by firing solid fuel degassed in the degassing reactor 1 and transferred to the degassing reactor 1 via partition walls 21 made of thermally conductive material.
• the fluidized bed furnace 2 is divided into a plurality of vertical chambers arranged parallel to one another. In the examples of FIGS. 5 and 6, however, only one chamber of the fluidized bed furnace 2 is shown in each case to simplify the pictorial representation.
• the gas contained in the degassing reactor 1 is drawn off in a filter system 5 via line 14 after solids separation.
• a filter system 5 For example, be used directly as a reducing agent for further nitrogen oxide reduction in the large combustion plant fired with the degassed solid fuel.
• Part of the gas is branched off via line 15 and, if necessary via a further gas cleaning 7, a blower 4 and a nozzle system 16 are returned to the degassing reactor 1 as fluidizing gas.
• the degassed fuel is fed into the fluidized bed furnace 2 pneumatically by means of injector nozzles 26, which are only indicated schematically in the figures, at the entry into the individual chambers of the fluidized bed furnace 2, inert gas and / or combustion air also supplied via line 25 as the conveying gas and fluidizing gas .
• the inert gas is expediently turned into flue gas from the smoke gas discharge line 23 of the fluidized bed furnace 2 is used.
• the ratio of flue gas to combustion air can be set in accordance with the oxygen requirement of the fluidized bed furnace 2.
• the chambers of the fluidized bed furnace 2 end within the fluidized bed 12, the degassed fuel being introduced into the fluidized bed 22 of the fluidized bed furnace 2 due to the suction effect of the injector nozzles 26 directly from the area above the nozzle base 17 of the fluidized bed 12 of the degassing reactor 1 .
• the degassing reactor 1 is charged with fresh solid fuel to be degassed in the surface area of its fluidized bed 12.
• the degassing reactor 1 is charged with fresh solid fuel to be degassed via the fuel feed 11 from below through the nozzle bottom 17.
• degassed solid fuel is returned to the fluidized bed furnace 2 via return channels 18 and 6 from the surface area of the fluidized bed 12 of the degassing reactor 1 from below into the fluidized bed furnace 2.
• degassed solid fuel can also be introduced into the fluidized bed furnace 2 from above through an overhead return duct.
• additional conveying gas is conducted into the return channels 18, 6 via nozzles 19, an inert gas advantageously being used as the additional conveying gas.
• the direct entry of the fuel into the fluidized bed combustion 2 takes place together with the inert gas / oxygen carrier mixture introduced via nozzles 26. It may be expedient to cover the oxygen requirement, for example to reduce the vertebrae Velocity in fluidized bed combustion 2- to be used as an oxygen carrier with oxygen-enriched combustion air or to operate the fluidized bed combustion under pressure and to introduce compressed combustion air.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Dispersion Chemistry (AREA)
• Materials Engineering (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)
• Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)

Applications Claiming Priority (4)

Publications (1)

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• 1989
  • 1989-10-14 DE DE19893934447 patent/DE3934447C2/de not_active Expired - Lifetime
• 1990
  • 1990-02-15 EP EP19900902760 patent/EP0458816A1/de not_active Withdrawn
  • 1990-02-15 AU AU50386/90A patent/AU5038690A/en not_active Abandoned
  • 1990-02-15 WO PCT/DE1990/000099 patent/WO1990009548A1/de not_active Application Discontinuation
  • 1990-02-15 JP JP50293690A patent/JPH04503400A/ja active Pending

Non-Patent Citations (1)

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