Classifications

• • 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
  • F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
  • F23G5/10—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating electric
• • 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
• • 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
  • F23G5/44—Details; Accessories
  • F23G5/46—Recuperation of heat
• • 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
  • F23G5/50—Control or safety arrangements

Definitions

• the present invention relates to a process and an incinerator for environmentally incinerating hospital waste and other solid waste containing fuel.
• Waste disposal must ensure complete incineration of the fuel at high temperature, incombustible residues and smoke must be free of germs, dangerous compounds and odors.
• Most of the hospital waste is incinerated with household waste in incineration plants. This process has the disadvantage of presenting a great risk of contamination during the transport of hazardous contaminated waste, or else of entailing high costs of disinfection before transport.
• incinerators They pollute the environment in particular during ignition and extinction, as well as when reloading waste in the oven, due to the significant formation of gas caused by ignition of the waste and combustion .
• the operation of such incinerators may be interrupted by variations in the composition and properties of the waste
• EP-A-0 251 269 describes a process and an apparatus for gasifying solid fuel and then burn gaseous gasification products.
• a gas generator for gasifying solid fuels such as wood, coal, briquette fuels, household waste, etc. is followed by burners for the combustion of gaseous products directly after gasification.
• the air supplying the gasification zone and the burner is heated with heat released during the gasification.
• the air is heated by passing the primary air and the secondary air through passages provided in a multiple wall of the gasification chamber.
• FR-A-2 649 782 describes a process intended to exclude pollution of the environment, regardless of the competence of the operator.
• the ignition, pyrolysis, combustion and cooling stages are carried out in sequence under continuous automatic piloting.
• the temperature is regulated by automatically controlling the air flow rate and operation of additional gas burners in corresponding chambers of the incinerator.
• additional gas natural gas
• the object of the present invention is to ensure the ecological incineration of hospital waste and other waste containing fuel, by minimizing the supply of external heat while ensuring stable operation for a wide range of compositions and properties of the waste, including including wet waste.
• a method for incinerating solid waste containing fuel, such as hospital waste comprising the following steps:
• a gasification step during which said waste, as the first component, is gasified with the addition of a gasifying agent constituting a second component
• a post-combustion step during which the gaseous products of the gasification step, as a third component, are burnt with the addition of a secondary oxidizing gas as a fourth component, characterized in that the heat produced by said post-combustion step is transferred to at least part of one to the less of said components before it is consumed in the corresponding one of said gasification and post-combustion stages.
• an incinerator for implementing the process, comprising a gasification chamber, for 4 contain a first component consisting of waste to be incinerated, means for introducing a gasification agent as a second component into said gasification chamber, a post-combustion chamber, means of fluid communication between the gasification chamber and the post-combustion chamber, so as to introduce into the post-combustion chamber a third component consisting of gaseous products originating from the gasification chamber, and inlet means for introducing into the post-combustion chamber a fourth component consisting into a secondary oxidizing gas, characterized by means for transferring heat from the post-combustion chamber to at least part of at least one of said components upstream of the post-combustion chamber.
• heat generated by the post-combustion step is used to preheat at least one of the components (waste and / or gasification agent) of the gasification process and / or one at less of the components (gaseous gasification products and / or secondary oxidizing gas) of the post-combustion itself.
• the gasification agent and the secondary air which feed the gasification and post-combustion chambers, respectively, or fractions thereof when treating relatively dry high calorific waste are preheated by recovering the heat of the fumes generated in the post-combustion chamber. This recovery is carried out by heat transfer through walls of gas conduits and / or chamber walls.
• the air serving as a gasification agent and / or secondary oxidizing gas can be guided through a heat exchanger mounted in the post-combustion chamber or in a chimney between the post-combustion chamber and the outside.
• the air flows can be subdivided so that only an adjustable proportion of the primary air (gasifying agent) and / or the secondary air, respectively, is preheated, while the other parts are sent directly to the rooms.
• the heat of the fumes can also be communicated to the waste which feeds the gasification zone as the preceding waste is consumed.
• Such heating can in particular be provided by arranging the gasification chamber so that the region where the gasification zone is located protrudes at least partially into the post-combustion chamber.
• the gasification and post-combustion process are controlled by regulating the consumption of the gasification agent and the secondary air and / or by redistributing the gasification agent and the secondary air between corresponding intake orifices, depending on the temperatures in the gasification zone and in the post-combustion chamber. Temperatures are kept within a range whose lower limit is defined by the need to avoid release of compounds organic, including dioxynes, in dangerous concentrations. The upper temperature limit is in particular determined by the ability of the materials constituting the incinerator to withstand heat. When the temperature in the gasification zone tends to exceed the prescribed limit, the feed rate of the preheated gasification agent is reduced so as to reduce the proportion of preheated gasification agent in the total flow rate of the gasification.
• the flow rate of the preheated secondary air is reduced, for example by correspondingly redistributing the flow rates towards respective intake orifices of the post-combustion chamber, so as to reduce the proportion of preheated secondary air in the total secondary air flow.
• the aforementioned controls can be provided automatically.
• the incinerator must then be fitted with a control device connected to probes to measure the temperature in the gasification chamber and in the post-combustion chamber, and to corresponding means, such as valves or fans controlled by speed, controlling the corresponding feed rates and the distribution of the gasification agent and the secondary air through the intake ports of the incinerator chambers as a function of these temperatures.
• this control can however be ensured by initial adjustments in the factory, by simple fitting of corresponding gas conduits, having correlated cross sections.
• the process can use air as a gasifying agent.
• steam can also be injected into the gasification agent so as to reduce the temperature in the gasification zone. The heat necessary to produce the steam can be recovered in the fumes.
• the successive displacement of the waste towards the gasification zone can be obtained by gravity of the waste and can be favored by a design and an appropriate size of the gasification chamber, for example by making the gasification chamber flared downwards, for example in a cone .
• this movement can be provided for example by a sort of agitator.
• the volume of the post-combustion chamber is chosen so that when the incinerator operates at its nominal capacity, the retention time of the fumes in the chamber is greater than the standard time required and is carried out under a temperature and a concentration of oxygen higher than the prescribed standard values, these retention times, standard temperature and concentration being determined with a view to certain decontamination of the fumes.
• the process can be started by a thermal pulse applied to the waste in the gasification zone and / or to the gasification agent flow, by means of an additional thermal source, for example an electric heater, the operation of which is interrupted once the gasification process has been established steadily.
• an additional thermal source for example an electric heater
• its power can be reduced to a reduced value, and preferably this reduced power is varied so as to increase when the temperature in the gasification zone drops below the prescribed lower limit.
• Such an order can be carried out automatically by the control device cited above, the latter then also being connected to means for adjusting the power of the additional thermal source.
• the incineration of waste containing dangerous components can also be supplemented by a purification of the smoke from the post-combustion chamber and / or the pyrolysis gases withdrawn from the gasification chamber to extracting harmful gases using known techniques, for example by passing the gaseous products through one or more layers of particles of limestone or other absorbent material and neutralizing these pollutants. If the purification step concerns the pyrolysis gases, for example these are passed through a conduit containing said materials and connecting the gasification chamber to the post-combustion chamber.
• the post-combustion chamber can be subdivided into separate volumes connected in series so that the fumes pass through them successively.
• One of these volumes is preferably arranged in a cyclone, the conduit leading to this volume being arranged to ensure a circular flow of gases therein.
• a cyclone dust the gases.
• the process can be carried out continuously.
• the incinerator can be equipped with means for continuously or intermittently loading the new waste into the gasification chamber and discharging the ash and other non-combustible during the operation of the incinerator.
• loading and unloading can be carried out by known means, for example by loading the waste by through an air lock.
• the waste can be loaded directly into disposable containers (provided that they are flammable, for example the usual polyethylene bags) these bags are also incinerated with waste.
• the supply of gasification agent is redistributed so that the surfaces internal parts of the gasification chamber are heat treated for disinfection.
• the gasification chamber can be equipped with an additional inlet port for hot gasification agent.
• the heating of this gasification agent can be provided in the same heat exchanger where the secondary air is preheated.
• the incinerator can be equipped, in addition to a chimney, with a draft assistance device, for example an extractor fan or an ejector. This guarantees a slight negative pressure in the chambers of the incinerator so as to avoid gas leaks from them.
• a draft assistance device for example an extractor fan or an ejector.
• the process described is less sensitive to variations affecting the composition and properties of the waste, and significantly increases the possibilities of treating waste with low calorific value, high ash content and very wet, with which due to small amounts of heat released, self-sustaining gasification is impossible without such preheating or additional heat output.
• FIG. 1 is a schematic view of an incinerator according to the invention
• FIG. 2 is a diagram similar to Figure 1, but on a slightly reduced scale and relating to a variant, with a detail II seen from above; and
• FIG. 3 is a schematic view of a laboratory incinerator according to the invention.
• the incinerator of Figure 1 comprises a vertically elongated gasification chamber 1 having an upper opening which is normally closed by a cover 21 or by a device allowing the continuous or discontinuous loading of waste 22 during operation.
• the cover is open, or thanks to such a loading device, the waste 22, such as hospital waste contained in disposable plastic containers, can be introduced into the gasification chamber 1.
• a lower part 24 of the chamber gasification 1 is defined by a perforated wall through which the gasification chamber 1 is in fluid communication with a post-combustion chamber 5, which is in turn in fluid communication with the outside through a chimney 23 for the fumes. Part 24 projects inside the post-combustion chamber 5.
• the wall defining the part 24 thus separating the interior of the gasification chamber 1 from the interior of the post-combustion chamber 5 is conductive of heat.
• Part 24 of the gasification chamber is provided with an inlet orifice 3 for a gasification agent, more particularly: air with the possible addition of water vapor in the example.
• a gasification agent more particularly: air with the possible addition of water vapor in the example.
• Electric heating means 12 are mounted in the vicinity of the part 24 of the gasification chamber, either in the post-combustion chamber 5 in the vicinity of a perforated part of the wall defining the part 24, or in the adductor duct d gasification agent just upstream of the inlet 3.
• the gasification gas products emerging from the gasification zone 2 flow through the perforated wall 24 into the post-combustion chamber 5.
• An inlet 6 is provided in the post-combustion chamber 5 near the perforated wall 24 for injecting into the post-combustion chamber 5 a secondary oxidizing gas, such as air, so as to burn the gaseous gasification products in the post-combustion chamber.
• the heating means 12 is used not only to initiate the gasification but also to initiate the ignition of the gasification gas products.
• Secondary air is introduced in more than stoichiometric amounts of so that the fumes 7 in the post-combustion chamber 5 contain excess oxygen in a proportion corresponding to the standards relating to the decontamination of gases.
• It is mounted in the post-combustion chamber 5 in the vicinity of the outlet thereof, a heat exchanger 8 in which air from an intake device 26 recovers heat from the flue gases which are on the point of leaving the post-combustion chamber 5.
• the air outlet of the heat exchanger 8 is connected to the gasification agent inlet port 3 and to a secondary oxidant gas inlet port 6 through a respective flow adjustment means 31, 32.
• the intake ports 3 and 6 are also connected to the air intake device 26 independently of the heat exchanger 8 through another means of respective flow rate adjustment 33, 34.
• the temperature of the gasification agent and of the secondary oxidizing gas can be adjusted by adjusting, for each of them, the proportions of preheated air and of fresh air - which compose them. .
• the gasification chamber 1 is also provided with an additional admission orifice 13 for introducing hot gasification agent at a location remote from the perforated wall 24, in the vicinity of the cover 21.
• the admission orifice 13 is supplied with hot gasification agent also in the form of hot air available at the outlet of the heat exchanger 8.
• the inlet orifice 13 is equipped with a flow control means 11.
• the flow adjustment means 11, 31 to 34 are connected to an automatic pilot device 9 which also controls the operation of the heating device 12.
• the heating device 12 is connected to temperature probes 10, one in the gasification chamber 1 and the other in the post-combustion chamber 5.
• the flow control means 11 of the additional intake port 13 is controlled to send hot gasifying agent through the intake port 13 when the gasification chamber is nearly empty as a result of near completion an incineration session, so as to heat disinfect the internal surfaces of the gasification chamber. But since the gasification chamber is not yet completely empty, gaseous products continue to be produced in the gasification zone and to burn in the post-combustion chamber, so that the heat exchanger 8 is still capable to produce hot gasification agent for the intake orifice 13.
• a draft assistance device 14, in the form of an ejector, is mounted at the outlet of the post-combustion chamber 5 to produce reliably a vacuum in the entire incinerator, so as to avoid the risk of leakage of harmful gas from the incinerator.
• a filter 37 consisting for example of one or more layers of limestone particles is also mounted at the outlet of the post-combustion chamber 5.
• the post-combustion chamber 5 is subdivided into two volumes 41, 42, which the fumes 7 pass through successively before leaving the chamber 5.
• the downstream volume 42 is arranged in a cyclone with a vertical axis so as to dust off the fumes.
• the gas conduit 43 through which the upstream volume 41 adjacent to the part 24 communicates with the downstream volume 42 has an opening of outlet directed in the circumferential direction of volume 42 to generate the cyclone effect.
• the conduit 43 opens at the top of the volume 42.
• An outlet conduit 44 allowing the fumes to exit from the volume 42 has an opening close to the base of the volume 42 and extends axially upward through the volume 42.
• the outer surface of the duct 44 serves as a rotation guide for the fumes 7 in the volume 42 around the duct 44.
• the heat exchanger 8 is placed downstream of the volume 42, between the latter and the ejector 14.
• a filter such that 37 (Figure 1) has not been shown in Figure 2 but could also be provided.
• the prototype incinerator shown in FIG. 3 was used for experimental tests and will be described at the same time as the following experimental examples.
• the temperatures in the gasification zone and in the post-combustion chamber were around 800 to 900 and respectively 1000 to 1100 ° C.
• the temperature of the flue gases leaving the post-combustion chamber behind the heat exchanger was less than 200 ° C.
• the afterburner discharges contained no visible dust and were odorless.
• Example 2 - 16% water was loaded into the laboratory incinerator described with reference to Example 1.
• the mass and density of the loaded mixture were 0.17 kg and 190 kg / m3, respectively.
• the temperature in the gasification zone and in the post-combustion chamber were about 900 to 1000 and 1100 to 1200 ° C, respectively; the temperature of the air supplying the chambers was around 500 to 600 ° C.
• the smoke temperature at the outlet of the post-combustion chamber (behind the heat exchanger) was below 250 ° C.
• the ooids of the non-combustible residue, consisting of glass 16 melt, sheet and ash was 0.02 kg; it contained no trace of residual carbon.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Gasification And Melting Of Waste (AREA)
• Processing Of Solid Wastes (AREA)
• Incineration Of Waste (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=26231359

Family Applications (1)

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Cited By (1)

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• 1995
  • 1995-06-22 AU AU29229/95A patent/AU2922995A/en not_active Abandoned
  • 1995-06-22 WO PCT/EP1995/002418 patent/WO1996000366A1/fr active IP Right Grant
  • 1995-06-22 EP EP95924900A patent/EP0834042B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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