Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D19/00—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium
  • F28D19/04—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier
  • F28D19/041—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier with axial flow through the intermediate heat-transfer medium
  • F28D19/042—Rotors; Assemblies of heat absorbing masses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
  • F28F21/02—Constructions of heat-exchange apparatus characterised by the selection of particular materials of carbon, e.g. graphite
• • 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
  • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Definitions

• the invention relates to a rotary heat exchanger for the recovery of heat from the exhaust air according to the preamble of the main claim.
• Such rotary heat exchangers transfer the heat from a warm raw gas stream to a colder clean gas stream using a suitable storage mass.
• a plurality of heating elements form the storage mass of a regenerative heat exchanger.
• the heat exchanger plates or heat exchanger tubes representing the storage mass are arranged in such a way that they form a rotor (1). The heat is removed from the warm gas stream and released to the colder one.
• the heat exchanger plates or heat exchanger tubes may consist of metallic materials, mostly of carbonaceous steels.
• metallic materials mostly of carbonaceous steels.
• it is customary to provide them with an enamel layer.
• the aging of enamel panels is based on the material combination of steel and enamel, which are unsuitable for frequent load changes due to the different thermal expansion coefficients. Due to this unavoidable aging and concomitant porosity of the enamel layer, the underlying steel sheet is subject to severe corrosion.
• the protection of existing metallic material heat exchanger plates or heat exchanger tubes is given only conditionally and therefore their regular renewal required.
• Such heat exchanger plates or heat exchanger tubes have experience to be completely replaced after an operating time of about four years.
• the storage mass required for regenerative heat transfer is subjected to further operational stresses when used in dusty gas streams.
• This applies for example, to the storage mass of air preheaters on boiler systems or gas preheaters on flue gas cleaning systems, where the temperatures of the storage mass at least locally and / or temporarily below the Rauchgastauliens and in conjunction with flue dust and / or other smoke ingredients (additives, means for flue gas cleaning) Make deposits on the storage mass or the heating surfaces of the heating elements. The latter increase the pressure loss for the flow through the storage mass and lead in the worst case to complete obstruction / blockage of the regenerative heat exchanger.
• Regenerative heat exchangers consist of a multiplicity of heating elements or heat accumulators which are heated by a hot gas, for example flue gas, and which subsequently release the stored heat to a colder fluid, for example air or gas.
• a hot gas for example flue gas
• a colder fluid for example air or gas.
• Such regenerative heat exchangers can be used, for example, as air preheaters or gas preheaters in boiler systems and flue gas purification systems.
• Air preheaters are designed according to the prior art so that the cold end temperature is above the so-called pollution temperature.
• the soiling temperature is the temperature at which deposits can no longer be controlled with economically justifiable expense as a consequence of dew point discrimination and the inclusion of flue dust (ash) in the smoke condensate (sulfuric acid and / or sulfurous acid and / or other acids).
• DE 4 337 895 discloses the use of heat exchanger plates made of carbon fibers reinforced polyarylketone or polybenzimidazole.
• Plastic storage masses are expensive and disadvantageous because they have a low heat capacity and heat conduction.
• WO 2001/045825 again discloses a method and an associated heat exchange device for treating a gas, wherein the application is designed especially for the energy production and for the removal of CO2 from exhaust gas or combustion gas.
• US 2001/0047862 A1 discloses special plate heat exchangers for use as gas / gas or gas / liquid heat exchangers whose fins and plates are generally made of carbon.
• the lowest possible flue gas outlet temperature (temperature of the flue gas after flowing through the regenerative heat exchanger) and thus also the lowest possible cold end temperature of the regenerative heat exchanger is aimed at with air preheaters.
• limits have hitherto been set for the depth of the cold end temperature because of too rapid formation of deposits and poor cleanability.
• the exhaust gas temperature in the air preheater should be lowered as far as possible, which is only possible with the help of corrosion-resistant and dirt-repellent heating surfaces.
• this task is not limited to corrosive flue gases from coal combustion plants, but extends mutatis mutandis to other corrosive gases regenerative heat exchanger, as they occur for example in steel mills.
• a rotary heat exchanger with a storage mass consisting of in a rotor (1) arranged heat exchanger plates or heat exchanger tubes, which absorb the heat from a warm gas stream and deliver to a colder gas stream, which is characterized in that the heat exchanger plates or the heat exchanger tubes consist of carbon composite materials and / or of graphite and / or of hard carbon.
• the rotary heat exchanger according to the invention consists of graphite or hard coal or graphite and hard coal.
• the heat exchanger plates or the heat exchanger tubes of the rotary heat exchanger according to the invention can also be coated.
• a particularly preferred coating on the otherwise rather rough surfaces of the heating elements extremely liable is to raise.
• Very thin layers are sufficient, preferably 20 to 200 ⁇ m.
• a preferred coating matehal is the class of PFA (perfluoroalkoxy polymers).
• PTFE polytetrafluoroethylene
• FEP polytetrafluoroethylene-perfluoroethylene copolymer
• ETFE ethylene-tetrafluoroethylene copolymer
• the new material combination now fulfills the required properties according to the invention: anti-adhesion properties and maximum corrosion resistance, that is to say the permeability known for plastics no longer plays a role because of the use of the carbon substrate, since carbon is inherently stable.
• a deposit formation is either prevented even at extreme dew point undershoot or at least it is much better controllable, which ultimately allows a lowering of the flue gas temperature below the usual level.
• a lower flue gas temperature means a higher boiler efficiency and thus a lower specific CO2 emission (emitted amount of CO2 per unit produced electrical energy) and the downstream of the air preheater plants (electrostatic precipitator, flue gas cleaning system) can be built smaller (lower investment, lower operating costs).
• Another advantage is that the dew point below (sulfuric acid expansions) is accompanied by a reduction of SO3 / H 2 SO 4 concentration in the flue gas and thus the risk of corrosion in downstream systems and the risk of aerosol formation is reduced.
• the carbon materials used according to the invention and / or carbon composite materials eg carbon thermoplastics or carbon resin compounds
• / or the materials graphite and / or hard carbon have a high temperature resistance and a resistance to aggressive media. Due to the low surface energy of these materials, no or only very few dust particles settle on the surface of such heat exchanger plates or heat exchanger tubes, so that the rinsing processes with hot water necessary for generic heat exchangers have to be carried out much less frequently to remove the added residues.
• the rinsing process can also be carried out much more frequently, since the materials according to the invention or plates or tubes, which are used here as storage nests, also withstand frequent temperature changes in practice without damage, since, for example, spalling of enamel layers or others Protective layers is not to be feared.
• the material according to the invention is much lighter than the generic rotary heat exchanger, whereby smaller drives are required for the heat exchanger and from which a lower energy consumption results.
• the conductivity of the materials used according to the invention is higher than the thermal conductivity of the conventional materials for the same area.
• Such rotary heat exchangers are thus more resilient, i. It is possible a higher throughput of the respective exchange medium.
• Another aspect of the present invention relates to the use of the rotary heat exchanger according to the invention.
• the rotary heat exchanger according to the invention is used because of its material for the recovery of heat from the exhaust air of power plants, in particular of flue gas desulphurisation plants
• the rotary heat exchanger according to the invention is therefore not limited solely to the gas / gas heat exchange due to its material nature in its use.
• the rotary heat exchanger according to the invention is advantageously produced in the plug-in method and connected in a form-fitting or frictionally engaged manner, it also being possible to use, for example, clamping methods.
• the individual heat exchanger plates or heat exchanger tubes are combined with each other to plate packs (2) or tube packages, from which the rotor (1) is constructed.
• the profiling of the plates which is necessary for some fields of application, can be carried out by customary shaping processes which are suitable for carbon products, for example near net shape by extrusion.
• the adaptation of the panel profile to the given heat exchanger can be done "on site".
• the life of a memory element according to the invention is up to 10 years due to the described properties of the materials used.
• the heat exchanger plates are subjected to a rinsing process every 0.5 to 8 hours.
• the materials according to the invention can preferably be produced in a per se known extrusion process. Very economical press-to-size processes with binder / carbon mixtures or polymer / carbon compounds or graphite compounds are also preferred.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Air Supply (AREA)

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Citations (11)

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• 2012
  • 2012-03-01 DE DE102012203278A patent/DE102012203278A1/de not_active Withdrawn
• 2013
  • 2013-01-31 WO PCT/EP2013/051974 patent/WO2013127594A1/fr not_active Ceased
  • 2013-01-31 CN CN201380012114.1A patent/CN104204712A/zh active Pending
  • 2013-01-31 EP EP13702995.5A patent/EP2820367A1/fr not_active Withdrawn

Patent Citations (11)

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