Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
  • F23L1/00—Passages or apertures for delivering primary air for combustion 
  • F23L1/02—Passages or apertures for delivering primary air for combustion  by discharging the air below the fire
• • 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
  • F23G5/002—Incineration of waste; Incinerator constructions; Details, accessories or control therefor characterised by their grates
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23H—GRATES; CLEANING OR RAKING GRATES
  • F23H7/00—Inclined or stepped grates
  • F23H7/06—Inclined or stepped grates with movable bars disposed parallel to direction of fuel feeding
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/02—Regulating fuel supply conjointly with air supply
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2207/00—Control
  • F23G2207/10—Arrangement of sensing devices
  • F23G2207/102—Arrangement of sensing devices for pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2207/00—Control
  • F23G2207/10—Arrangement of sensing devices
  • F23G2207/112—Arrangement of sensing devices for waste supply flowrate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
  • F23G2207/00—Control
  • F23G2207/10—Arrangement of sensing devices
  • F23G2207/113—Arrangement of sensing devices for oxidant supply flowrate
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/04—Measuring pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2241/00—Applications
  • F23N2241/18—Incinerating apparatus

Definitions

• the present invention relates to a process for incinerating solid combustible material, in particular solid combustible refuse, as described in the preamble of the first claim.
• solid combustible material in general is referred to as well as solid refuse material in particular.
• an incineration process in which the combustion of solid combustible material can be controlled on a permanent basis is highly desirable for a number of reasons.
• a stable combustion facilitates meeting the emission standards imposed by law for exhaust gasses, flue dust and ashes.
• energy costs for maintaining the optimal combustion conditions can be minimised.
• temperature variations within the incinerator also the variations in the thermal and mechanical loads to which the incinerator is subjected can be minimised, which in turn will lead to an extended lifetime of the incinerator, in particular of the feeding and combustion grate.
• a refuse incinerator may be complicated by variations occurring in a.o. size and density of the refuse which is mostly supplied in the form of more or less dense packs, and variations in the composition of the refuse, for example its water content, which lead to variations in the calorific value of the refuse. Variations in these parameters may largely complicate the process and its control system, in particular in case the control system aims at constant steam production output, wherein a steam controller controls the refuse combustion rate.
• the steam controller controls the amount of primary combustion air supplied to the incinerator, based on the steam output.
• the primary combustion air is responsible for the maintenance of the combustion process.
• a second known system that aims at constant steam output, the latter is controlled by controlling the amount of refuse supplied to the incinerator. Thereto, the speed of the grate supplying the refuse to the oven is varied.
• Such a system often entails the problem of involving an overloaded combustion grate system, especially in case the refuse is rather dense and the primary air is hardly capable of penetrating the refuse. As a result, the refuse may be incompletely burned, even when supplying a large amount of primary air.
• the method disclosed in US-A-5.398.623 has the disadvantage that the system with which the amount of refuse on the combustion grate system is monitored and controlled is one and the same system, i.e. the hydraulic drive mechanism that drives the combustion grate system.
• the speed of the combustion grate system is controlled by adjusting the flow rate of the hydraulic liquid in the hydraulic drive mechanism.
• the hydraulic pressure as such in the drive system is varied and the hydraulic pressure measured will no longer correspond to the amount of refuse present on the combustion grate system.
• ⁇ P ro is the optimum gas pressure difference over the refuse bed on the carrier, which corresponds to an optimum incineration process and is representative for the optimum amount of refuse on the carrier.
• ⁇ P ro is representative for the optimum amount of refuse on the carrier
• the difference ⁇ P r is proportional to the resistance sensed by the gas, when flowing from the primary air inlet through the refuse towards the incineration zone and gives s an indication of the amount of refuse on the carrier
• ⁇ P ro corresponds to the pressure difference over the carrier that corresponds to an optimum combustion process.
• ⁇ P is the difference between an actual pressure difference over the carrier and the optimum pressure difference over the carrier 0 6) at least one of the speed of the charging ⁇ J the combustible material to the incineration zone or the feeding of the combustible material through the incineration zone is adjusted to minimise ⁇ P.
• the speed of the carrier for the refuse is controlled by adjusting the hydraulic pressure of the mechanism which drives the carrier.
• the amount of refuse present on the carrier is determined by measuring the gas pressure difference over the carrier in the incinerator. In that way the driving of the carrier is uncoupled from the measurement of the amount of refuse on the carrier, so that interference of both phenomena can be prevented and a reliable measurement of the amount of refuse on the carrier can be done.
• This uncoupling of both mechanisms entails the advantage that the carrier can be driven in a continuous manner and operated at varying speed, and still allow a reliable measurement of the amount of refuse on the carrier.
• the speed of the grate can be controlled in a continuous manner.
• the movement of the carrier can namely be described as a repeated alternating, slow, back and forth sliding in an approximately continuous manner, to advance the refuse over the carrier. Because the carrier can be driven in an approximately continuous manner, there is no necessity to provide dead times between the back and forth sliding of the carrier and the speed with which the carrier is displaced can be kept rather low.
• ⁇ P is divided by the square of the volumetric primary air flow rate v 2 pa (m 3 /s) 5 through the carrier, as a pressure difference over a duct, i.e. a combustion grate element, is always proportional to the square of the flow through that duct.
• An example of pressure variations that are not important to the incineration process as o such, is in case the carrier comprises a plurality of subsequent grate elements, the dropping of an amount of refuse from one element on the next element.
• the incineration zone is divided into a plurality of individual combustion zones, primary combustion air being supplied to each individual zone, the primary combustion air supply flow rate being adjusted for each individual air supply or incineration zone.
• the actual gas pressure P 9 Z at each o primary combustion air inlet device and the actual pressure P' z above the carrier in each individual incineration zone z is measured and ⁇ P r z is calculated for each zone.
• the values of P' z can be approximated to reasonable accuracy by a single measurement of P 1 in the incinerator.
• the flow rate v pa is measurable and adjustable for each zone.
• Primary combustion air is supplied to the incinerator through a primary combustion air supply device.
• the primary combustion air supply device comprises an inlet through which primary combustion air is supplied to the primary combustion air supply device and an outlet through which primary combustion air is supplied from the primary combustion air supply device to an incineration zone of the incinerator.
• the flow rate of the primary combustion air in each individual zone is measured by determining
• each air supply device has a characteristic curve from which the flow rate corresponding to the pressure difference between the inlet and outlet of the primary combustion air supply device can be determined.
• an air supply device use can be made of devices that are generally known in the art, for example an air fan or an air supply valve.
• the calculation may be corrected for variations in the rotation speed of the fan. Determination of the flow rate of the primary combustion air per combustion zone is also possible when primary air is supplied through the existing technique of one single fan, from which the primary combustion air is distributed towards the individual incineration zones through gas control valves, for example butterfly or register valves. In that case the pressure difference over the control valve is measured, and a calculation is done based on the characteristic curve of the control valve instead of the characteristic curve of the fan.
• the present invention also relates to a device for incinerating solid combustible material, the device comprising an incineration reactor with at least one incineration zone for combusting the combustible material, a carrier for carrying the combustible material and feeding the combustible material through the at least one incineration zone, a device for supplying combustion air below the carrier and means for adjusting the amount of combustible material in the incineration zone.
• the carrier for the combustible material preferably comprises a plurality of individual grate elements for advancing the combustible material through the incineration zone, a primary combustion air supply device being provided below each grate element, to allow an improved control of the incineration process.
• the most used technique for supplying primary combustion air to the incinerator at this moment makes use of one single air fan. From the air fan primary combustion air distribution over and along the different combustion grate elements is controlled by means of butterfly or register valves.
• the combustible material is preferably advanced through the incineration zone by means of a carrier comprising a plurality of subsequent carrier elements, some of which are slideably mounted in forward and backward direction for transporting the refuse from a former combustion zone to a next combustion zone.
• carrier elements preferably use is made of individual combustion grate elements.
• Each carrier element preferably comprises a first combustion grate element that is slideably mounted in forward and backward direction for transporting the refuse from a former combustion zone to a next combustion zone.
• Between subsequent first combustion grate elements preferably at least one second combustion grate element is mounted, the second combustion grate elements being mounted in such a way that they can be tumbled, preferably over a preset angle to improve thejntensity of the combustion.
• a third stationary combustion grate element is provided.
• the first and second combustion elements are individually and separately controllable.
• the device further preferably comprises a burn out control device to ensure that the solid combustible material has been completely burned before it is removed from the incinerator.
• Figure 1 shows a cross section through a reactor for the incineration of refuse.
• Figure 2 shows a detail of a combustion grate system for use in the method of this invention.
• the incinerator shown in figure 1 comprises overhead cranes for transferring solid combustible material, for example refuse 1 to a reactor feed hopper and a loading chute 3.
• the chute in fact functions as an air seal for the top of the incinerator, but is also provided for distributing the refuse 1 to a refuse supply device 4 with which the refuse is supplied to a carrier 5 for transporting the combustible material through the incinceration zone where it is combusted.
• the carrier 5 can be any carrier known to those skilled in the art, but preferably comprises a combustion grate system 5.
• the combustion grate system is further provided for drying the combustible material, igniting and burning it in the gasification and combustion zone.
• primary combustion air is supplied to the incinerator through a primary combustion air supply device 9, which is preferably located below the combustion grate system.
• the primary combustion air supply device 9 may for example comprise an air supply fan or valve or any other primary combustion air supply device known in the art.
• the device further preferably comprises a burn out control device to ensure that the solid combustible material is completely burnt out before it leaves the incinerator.
• the combustion grate system 5 used in the incinerator of this invention preferably comprises a plurality of combustion grate elements (11-16), the degree of combustion of the combustible material increasing from a former to a subsequent combustion grate element.
• the combustion grate elements 11-16 further function as a means for transporting the combustible material 1 from the feed hopper 3 to a former to a next combustion grate element, and finally to an ash discharge 6.
• an air supply device is provided below each grate element 11-16 to provide an improved control of the combustion process.
• an air supply device preferably use is made of a valve or a fan, but other air supply devices known in the art may also be used.
• Each air supply device comprises an inlet through which primary combustion air is supplied and an outlet through which the primary 5 combustion air leaves the air supply device towards the incinerator.
• Means are provided for determining the air flow rate at the outlet of the primary air supply device. This can be done by actually measuring the pressure at the inlet and outlet of the primary combustion air supply device and determining the corresponding flow from the characteristic curve of the air o supply device.
• the combustion grate system 5 preferably comprises a plurality individual grate elements, preferably a plurality of subsequent sliding tiles, 11-16, with which the layer of the combustible material is displaced over the combustion grate.
• the sliding movement of the tiles is s preferably a slow, continuous movement, so as to avoid dust generation in the incinerator and increase the life time of the incinerator. Besides this, when continuously moving the tiles 11-16, a virtually continuous steam production and consequently a virtually continuous electricity production can be ensured.
• the sliding tiles 11-16 determine the thickness of the o layer of the combustible material, the residence time of the combustible material in each combustion zone and the combustion quality.
• the combustion grate system 5 further preferably comprises a plurality of tumbling tiles (17-20), which disentangle and aerate the refuse. This is important for drying and ignition of the refuse, to 5 activate the combustion where and if necessary and to obtain a complete burn-out of the ashes.
• This combination of horizontal throughput action and vertical aeration action (tumbling) allows the incinerator to adapt to short and long term fluctuations in the composition of the refuse.
• the throughput (sliding) and aeration (tumbling) can be o controlled for each individual zone (combustion grate element).
• an independent control of the two motions i.e. the sliding and tumbling is highly desirable.
• the tumbling action is stopped automatically because of the increased risk of dust production when disentangling and more intense aeration of the refuse is not necessary.
• the speed of the 5 charging of the combustible material to the incineration zone or the feeding of the combustible material through the incineration zone is adjusted to minimise ⁇ P.
• the speed of the feeding of the combustible material is adjusted to ⁇ P/v 2 pa , wherein v pa is the flow rate of the primary combustion air.
• ⁇ P/v 2 pa is measured at predetermined time intervals and o averaged as a function of time or ⁇ P/v 2 pa is filtered.
• the primary air flow rate in each individual combustion zone is measured by determining a pressure of the primary air pressure at the inlet and outlet of the air supply device, determining the pressure difference between the inlet and outlet, calculating the flow rate corresponding to the measured pressure difference.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Incineration Of Waste (AREA)
• Processing Of Solid Wastes (AREA)
• Gasification And Melting Of Waste (AREA)
• Crucibles And Fluidized-Bed Furnaces (AREA)
• Solid-Fuel Combustion (AREA)
• Treatment Of Sludge (AREA)

Applications Claiming Priority (1)

Publications (2)

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ID=3862545

Family Applications (1)

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Cited By (2)

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• 2000
  • 2000-04-21 ES ES00918617T patent/ES2265927T3/es not_active Expired - Lifetime
  • 2000-04-21 WO PCT/BE2000/000037 patent/WO2001081827A1/en not_active Ceased
  • 2000-04-21 EP EP00918617A patent/EP1274961B1/de not_active Expired - Lifetime
  • 2000-04-21 CN CN008195846A patent/CN1217128C/zh not_active Expired - Lifetime
  • 2000-04-21 AU AU2000239507A patent/AU2000239507A1/en not_active Abandoned
  • 2000-04-21 PT PT00918617T patent/PT1274961E/pt unknown
  • 2000-04-21 AT AT00918617T patent/ATE330177T1/de not_active IP Right Cessation
  • 2000-04-21 DE DE60028833T patent/DE60028833T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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