Classifications

• • 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
  • F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
  • F23G7/061—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating
  • F23G7/065—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel
  • F23G7/066—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel preheating the waste gas by the heat of the combustion, e.g. recuperation type incinerator
  • F23G7/068—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases with supplementary heating using gaseous or liquid fuel preheating the waste gas by the heat of the combustion, e.g. recuperation type incinerator using regenerative heat recovery means

Definitions

• the dimensions of the electric heating system in an electrically heated combustion exchanger generally are chosen to ensure that the installation can be operated at full air flow and maintain the operational temperature, also when the air temporarily contains no pollutants that generate energy. In other words, the installation should be able to function also with clean air.
• One consequence of this is that the electric connections must be dimensioned for considerable power requirements.
• it is costly to have to provide for considerable power for the electric heaters with consequential large connected power which means considerable costs, although the equipment perhaps is in use only very unfrequently.
• the use of equipment designed to supply extra fuel to the strem of air to be cleaned may, under these circumstances, result in cost savings, since it becomes possible to reduce the electric power connections. This is prior-art technology and is used in many cases in conjunction with conventional combustion exchangers.
• the electric heaters are positioned in the hottest zone of the bed.
• the tem ⁇ perature is high in this zone (about 1000°C), with con- sequential high demands on the corrosive resistance of the materials of which the heaters are made. This is true whether the heat is supplied by electricity, by the pollutants or by the fuel added to the flow.
• the problem is identical when using other types of heaters than electric heaters.
• a combustion exchanger may be arranged in such a manner that any heaters incorporated therein are spared long-term presence in high temperatures.
• Fig. 1 One embodiment of the invention is illustrated in Fig. 1.
• the incoming air to be cleaned enters through a conduit 1 and is supplied to an air-direction changing apparatus 2 in which the air is alternatingly directed upwards to an air distribution space 3 and downwards to an air distribution space 4. From there, the air passes through a combustion bed 5 in which the chemical reaction takes place. Via the air distribution space 4, alter ⁇ natingly the air distribution space 3, the air then returns to the air-direction changing apparatus 2 and finally the cleaned air exits thorugh a conduit 6.
• the direction of the air is changed at regular intervals, in accordance with the principle described in the US Patent Specification referred to in the afore ⁇ going.
• heat losses are compensated for by the heat developed in the reaction process with the pollutants and/or with the fuels mixed with the air for this very purpose.
• a higher temperature is, however, required initially in order to initiate the chemical reactions.
• the necessary starting temperature in the bed is achieved by means of one or several heaters 7 which are positioned vertically out of center, i.e. displaced from the central part of the bed, and which preferably are located at the upper part of the bed.
• the heaters 7 are activated. They are used to heat a layer in the bed up to a starting temperature which need not be as high as the normal operational temperature. It is sufficient if the temperature level is such as to ensure that the mixture of pollutants/fuel and air starts to react during its passage through the layer and that the reaction progresses to a point where more heat is devel ⁇ oped inside the layer than is removed therefrom. The temperature inside the layer will therefore rise while the installation is in operation. When the correct start-up temperature level has been achieved by means of the heaters, the latter thus are stopped and by starting the supply of the air flow and the supply of pollutants/fuel, the temperature of the hottest layer will soon increase up to the normal operational temperature.
• the layer will lose more heat upwards than downwards. Consequently, the heat has a tendency to move downwards and eventually it will be centered in the bed.
• the air-directing mechanism By controlling the air-directing mechanism in such a manner that a larger volume of air passes downwards through the bed than upwards, this process may be accel ⁇ erated and become so rapid that the heaters, having starducy positions inside the bed, will never be exposed to the normal working temperature.
• the simplest way to achieve this is to allow the flow to pass upwards and downwards at intervals of mutually different lengths, but it is likewise possible to keep the interval times of equal length but instead vary the flow volumes per time unit.
• heaters in combustion exchangers are electric heaters.
• the principle of asymmetrically positioned heaters as defined in the subject invention is applicable also to other types of heaters, such as oil or gas fuelled heaters.

Landscapes

• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Air Supply (AREA)
• Incineration Of Waste (AREA)
• Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
• Gas Burners (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20384676

Family Applications (1)

Country Status (8)

Citations (2)

• 1991
  • 1991-12-19 SE SE9103786A patent/SE9103786L/sv not_active IP Right Cessation
• 1992
  • 1992-08-24 DE DE69217503T patent/DE69217503T2/de not_active Expired - Lifetime
  • 1992-08-24 JP JP51082393A patent/JP3217364B2/ja not_active Expired - Fee Related
  • 1992-08-24 AU AU26973/92A patent/AU2697392A/en not_active Abandoned
  • 1992-08-24 WO PCT/SE1992/000574 patent/WO1993012381A1/en active IP Right Grant
  • 1992-08-24 CA CA 2123884 patent/CA2123884A1/en not_active Abandoned
  • 1992-08-24 EP EP93911644A patent/EP0616673B1/en not_active Expired - Lifetime
  • 1992-08-24 ES ES93911644T patent/ES2097510T3/es not_active Expired - Lifetime

Patent Citations (2)

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