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
  • C10B1/00—Retorts
  • C10B1/10—Rotary retorts
• • 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
  • C10B47/28—Other processes
  • C10B47/30—Other processes in rotary ovens or retorts
• • 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
  • F23G5/02—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment
  • F23G5/027—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage
  • F23G5/0273—Incineration of waste; Incinerator constructions; Details, accessories or control therefor with pretreatment pyrolising or gasifying stage using indirect heating
• • 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
  • F23G5/20—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having rotating or oscillating drums
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2201/00—Pretreatment
  • F23G2201/30—Pyrolysing
  • F23G2201/303—Burning pyrogases

Definitions

• the present invention relates to a method and an apparatus for heating a rotary kiln for gasification and pyrolysis of organic material.
• a heating of the material is usually performed by means of a heating medium being caused to transfer heat to the material without direct contact, whereby the organic material is decomposed into pyrolytic gas and coke, subsequently usable for different purposes.
• a heating medium being caused to transfer heat to the material without direct contact, whereby the organic material is decomposed into pyrolytic gas and coke, subsequently usable for different purposes.
• the cold organic material is supplied at one end and is heated during its flow through the rotary kiln, ultimately leaving the rotary kiln at the opposite end in the form of hot pyrolytic gas and coke.
• the heating of the rotary kiln is usually performed by supplying a heating medium like e.g. hot flue gas to a jacket surrounding the rotary kiln or to a bundle of tubes, positioned longitudinally in the rotary kiln, through which the heating medium is circulated.
• a heating medium like e.g. hot flue gas
• the heating medium possessing a high temperature when introduced into the system is gradually cooled, the heat being transferred through the wall of the rotary kiln or tubes, whereby the organic material is heated.
• the heating medium is supplied with energy by burning a secondary fuel, or in certain circumstances by burning the pyrolytic gas, in an external combustion process.
• the pyrolytic gas generated by pyrolysis contains major amounts of condensable material which means that parts of the gas will condensate, if the temperature decreases during the removal of the gas from the plant. Often it is not sufficient to lead the gas away in isolated tubes and accordingly, it has been suggested to heat these tubes by means of a heating jacket, which however has appeared to lead to carbonization of parts of the pyrolytic gas, whereby the tubes are clogged by such carbonized material.
• a rotary kiln for gasifying waste material in which oxidizing agent for combustion of the gases developed by the process is supplied via a lance positioned longitudinally and openly in the rotary kiln and in which the supply of oxidizing agent can be controlled over the length of the rotary kiln in order to control the temperature distribution.
• This construction has a number of disadvantages.
• the oxidizing agent can inadvertently come into direct contact with the waste material in such places, where sufficient gas production and temperature to maintain a flame are not present, e.g. at the infeed end for waste material. This means that oxidizing conditions will be present around the waste material with consequent risk of formation of toxic components and risk of gas explosions.
• the flames radiate directly onto the waste material and may hit the waste material resulting in the risk of local overheating and consequently unwanted reactions.
• the liberation of gas from the waste material will be unevenly distributed over the length of the rotary kiln and with varying calorific value and composition in such a way that it will hardly be possible to control the combustion and thereby the heat production via the separate nozzles.
• a controlled temperature distribution in the rotary kiln which can be adapted to optimum operation conditions for the desired gasification and pyrolysis, can be achieved.
• the energy supply to the radiation heat exchanger is preferably provided by combustion of a combustible gas inside the radiation heat exchanger, .
• this combustible gas preferably being the pyrolytic gas provided by gasification and pyrolysis of the organic material, preferably being led through the inside of the radiation heat exchanger in opposite flow direction of the flow direction of the organic material inside the rotary kiln
• the pyrolytic gas preferably being supplied with a controlled amount of combustion air, preferably being controlled with respect to both amount and position for the supply of the combustion air, in such a way that the energy supply can be controlled over the length of the radiation heat exchanger.
• the combustion air is preferably supplied to the pyrolytic gas via an air lance comprising suitable air nozzles over the length of the lance in such a way that a suitable distribution of the energy supply over the length of the radiation heat exchanger is achieved.
• the air lance can be mounted axially movable inside the radiation heat exchanger in order to control the position for supply of energy to the radiation heat exchanger.
• the plant is provided with a preheating arrangement for starting up the plant.
• FIG. 1 shows a plant in accordance with the invention which is suitable to carry out the method in accordance with the invention.
• the plant shown in Fig. 1 comprises a rotary kiln 1 which is isolated and lined, in order to maintain constant temperatures in the rotary kiln during the operation thereof.
• the rotary kiln 1 is connected to an isolated and lined reversing chamber 5.
• the organic material to be gasified and pyrolised inside the rotary kiln 1 is supplied at the inlet end of the rotary kiln 1 by means of a feeding system 4, the further advancement of the organic material being provided by means of the rotation of the rotary kiln 1.
• a radiation heat exchanger 2 is positioned directly connected to the gas discharge tube 9.
• An air lance 3 is mounted axially movable inside the radiation heat exchanger 2.
• Air 10 is supplied via one end of the air lance 3 and is blown out through air nozzles 7 which are positioned in the outer wall of the air lance and distributed over the length of the air lance.
• the air lance 3 may be constructed with separate channels connected to separate air nozzles 7, debouching into different zones inside the radiation heat exchanger 2.
• the control of the position of supply of combustion air inside the radiation heat exchanger 2 may be performed by the axial displacement of the air lance 3 and by controlling the amount of supplied air 10, the distribution of the air nozzles 7 over the air lance may in advance be adapted to the optimal distribution of the energy supplied to the radiation heat exchanger 2.
• the embodiment of the plant in accordance with the invention shown in Fig. 1 comprises an oil or gas burner 6 positioned in the reversing chamber in order to start up the gasification and pyrolysis process.
• this preheating system 6 When starting up the plant, this preheating system 6 is started and the heat therefrom is sucked into the radiation heat exchanger 2, thereby being heated and liberating its heat to the rotary kiln 1.
• organic material When the desired operation temperature has been reached, organic material is supplied to the rotary kiln 1. The organic material is then heated, partly by direct radiation from the radiation heat exchanger 2, partly by contacting the hot lining of the rotary kiln 1 which is continuously heated by the radiation heat exchanger 2. When the organic material is heated, the volatile constituents are liberated as pyrolytic gas 8.
• the pyrolitic gas 8 is sucked out of the rotary kiln 1 and in through the radiation heat exchanger 2 and onwards to the outlet 9 for pyrolytic gas.
• air 10 By adding air 10 through the air nozzles 7 of an air lance 3, a partial combustion of the pyrolytic gas 8 will be induced.
• the pyrolytic gas may ignite spontaneously by adding air and depending on the amount and position of the air supply the radiation heat exchanger 2 will be heated to a certain extent.
• the preheating system 6 may be turned off and the control of the temperature of the rotary kiln 1 can then be provided alone by partial combustion of a greater or lesser part of the produced pyrolytic gas 8.
• the radiation heat exchanger 2 may be supplied with energy in another way than by combustion of part of the pyrolytic gas, although this is preferred, and as mentioned above gives the further advantages that the pyrolytic gas is heated to avoid condensation and the more condensable parts of the pyrolytic gas being burned first, whereby the tendency of condensation of parts of the pyrolytic gas is further reduced.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• General Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Combustion & Propulsion (AREA)
• Gasification And Melting Of Waste (AREA)
• Processing Of Solid Wastes (AREA)
• Muffle Furnaces And Rotary Kilns (AREA)
• Treatment Of Sludge (AREA)
• Incineration Of Waste (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (7)

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• 1998
  • 1998-05-26 AU AU76391/98A patent/AU7639198A/en not_active Abandoned
  • 1998-05-26 WO PCT/DK1998/000213 patent/WO1998054273A1/en active IP Right Grant
  • 1998-05-26 DK DK98924060T patent/DK0985009T3/da active
  • 1998-05-26 ES ES98924060T patent/ES2196561T3/es not_active Expired - Lifetime
  • 1998-05-26 AT AT98924060T patent/ATE236232T1/de not_active IP Right Cessation
  • 1998-05-26 EP EP98924060A patent/EP0985009B1/de not_active Expired - Lifetime
  • 1998-05-26 DE DE69812932T patent/DE69812932T2/de not_active Expired - Fee Related

Non-Patent Citations (1)

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