[go: up one dir, main page]

EP0482161B1 - Procede de regeneration thermique - Google Patents

Procede de regeneration thermique Download PDF

Info

Publication number
EP0482161B1
EP0482161B1 EP91908839A EP91908839A EP0482161B1 EP 0482161 B1 EP0482161 B1 EP 0482161B1 EP 91908839 A EP91908839 A EP 91908839A EP 91908839 A EP91908839 A EP 91908839A EP 0482161 B1 EP0482161 B1 EP 0482161B1
Authority
EP
European Patent Office
Prior art keywords
mixture
fluidised bed
bed
fed
sand
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91908839A
Other languages
German (de)
English (en)
Other versions
EP0482161A1 (fr
Inventor
Ian Arthur Bailey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RICHARDS ENGINEERING Ltd
Original Assignee
RICHARDS ENGINEERING Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RICHARDS ENGINEERING Ltd filed Critical RICHARDS ENGINEERING Ltd
Publication of EP0482161A1 publication Critical patent/EP0482161A1/fr
Application granted granted Critical
Publication of EP0482161B1 publication Critical patent/EP0482161B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
    • B22C5/08—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by sprinkling, cooling, or drying

Definitions

  • This invention relates to a method of thermally reclaiming a material, such as foundry sand (DE-C-3 903 604).
  • Used foundry sand is normally subjected to reclamation so that it can be re-used in foundry processes.
  • Such reclamation can take the form of mechanical attrition, whereby the sand is broken down into grain-size particles.
  • used foundry sand contains a high proportion of chemical bonding agents, notably phenolic resins, and after a while these agents reach such a level that the sand becomes unusable, even with mechanical reclamation. Consequently, there is a need for a thermal reclamation technique whereby the chemical agents are incinerated, leaving relatively clean sand ready for re-use.
  • Such reclamation is typically conducted in a furnace having a fluidised bed.
  • the reaction in the fluidised bed is substantially self-sustaining. That is to say, in theory at least, once the combustion process has reached a steady state from start-up (typically at around 800°C), there is no need to supply significant amounts of fuel gas since the combustion is supported by burning of the chemical agents instead. In practice, however, this does not happen for the following reasons.
  • the sand/bonding agent mixture is bed into the fluidised bed from above, and will comprise a mixture of relatively light particles (i.e. dust) and relatively heavy particles.
  • the velocity of the air passing through tie fluidised bed (which must be above the minimum required to maintain fluidity) is such that it exceeds the settlement rate of the relatively light particles and carries these upwardly into the hood and stack of the furnace. This effect is compounded by expansion of the air as it is heated by the bed.
  • the relatively light particles tend to comprise a high proportion of the bonding agent (up to 50% in some cases), they have a high calorific value and will burn in the hood or stack, subject to there being sufficient oxygen available. This causes excessive heat generation in the upper parts of the furnace.
  • the relatively heavy particles are also highly volatile, with the result that ignition tends to occur spontaneously as the particles impinge upon the top of the fluidised bed, so the bulk of the combustion takes place in the top region of the bed. This not only acts against the supposed self-sustaining reaction of the combustion, but also adds to the heating effect on the hood and stack. These effects combined gave rise to excessive heat in the flue gases, and indeed it is sometimes the case that the flue gases end up hotter than the fluidised bed itself.
  • the silos or hoppers containing the mixture must be provided at an elevated location for gravity feed of the material into the bed. This in itself gives rise to a degree of inconvenience.
  • a method of thermally reclaiming a base material from a mixture of the material and a combustible substance, wherein said substance is incinerated in a fluidised bed comprising mechanically comminuting said mixture, mixing dust from the comminution process with said mixture, and feeding said mixture directly into a lower part of the fluidised bed.
  • said mixture is fed into the fluidised bed from beneath the latter.
  • said mixture is fed (preferably continuously) to a confined space beneath the fluidised bed by means of a mechanical conveyor.
  • said mixture can be fed to the fluidised bed by a pneumatic conveyor, and is preferably injected into the bed at substantially the same level as the fluidising air/gas mixture.
  • a plurality of feeds are preferably provided which operate in sequence. For example, where two such feeds are provided, these can operate alternatively.
  • a first embodiment of apparatus comprises a furnace 10 containing a fluidised bed 11 to which an air/fuel gas mixture is supplied by way of a manifold 12, pipes 13 and nozzles or bubble caps 14. Above the fluidised bed 11 the furnace has a hood 15 and a stack 16 through which flue gases can pass, while to one side of the bed there is an exit chute 17 through which material can be drawn off from the top of the bed.
  • material to be reclaimed such as a comminuted mixture of foundry sand and phenolic resin bonding agent
  • a mechanical conveyor 19 such as a screw conveyor
  • the continuous feed of this material causes the mixture to rise progressively through the space 20 and to enter the fluidised bed 11 from below, through the interstices between the bubble caps 14. This ensures that all of the material, i.e. both relatively light and relatively heavy particles, is passed through the full body of the fluidised bed 11 and that therefore the resin bonding agent is properly incinerated within the bed itself.
  • the fluidised bed can be arranged to achieve the theoretical self-supporting combustion reaction, so that the quantity of fuel gas used can be drastically reduced once the bed has reached its steady state from start-up. Moreover, because there is no combustion in the space above the bed, the flue gases can be kept at a much lower temperature than has previously been the case. Furthermore, because the material is fed into the bed substantially uniformly across its area, no localised cold spots are created.
  • FIG. 2 shows a second embodiment of the apparatus wherein the sand/bonding agent mixture is fed to the fluidised bed 11 by means of a pneumatic conveyor 22. More particularly, a pressure vessel 23 is periodically charged with the mixture from a silo/hopper 24 via a valve 25. The pressure vessel 23 communicates with a manifold 26, which in turn communicates with pneumatic conveyor lines 27 by way of respective valves 28. The lines 27 terminate at respective injection nozzles 29 disposed at approximately the same level as the bubble caps 14.
  • the valve 25 is closed and the vessel 23 is pressurised so that the mixture is conveyed pneumatically to the bed 11 through the lines 27 and the nozzles 29.
  • the sand/bonding agent mixture is fed directly into the lower part of the fluidised bed 11 and passes upwardly therethrough as it is processed. Consequently, the bonding agent is properly incinerated in the bed itself, and there is no combustion in the space above the bed.
  • This embodiment also has the added advantage that oxygen is fed into the bed not only in the normal manner with the fuel gas through the bubble caps 14, but also in the air employed in the pneumatic conveyor 22. Injection of the material into the bed can be made as uniform as possible (to avoid the creation of any cold spots) by providing as many injection nozzles 29 as is practicable across the whole area or the fluidised bed.
  • processed material i.e. clean sand
  • exit chute 17 as the level of the top of the fluidised bed 11 rises above a weir 21, while material for reclamation is continuously fed into the bed from beneath.
  • the material Before processing in the fluidised bed, the material is subjected to mechanical attrition to break it down into grain-sized particles. This process does however create a great deal, of dust, which tends to contain a high proportion of the bonding agent. Such dust is a so created in other processing operations carried out on the material. Care has to be taken in incinerating this dust, since noxious vapours can be given off if the incineration temperature is not high enough. If desired, the material fed into the apparatus can be mixed with such dust, which will ensure that the dust is properly incinerated in the fluidised bed.
  • FIG. 3 shows a practical version of the apparatus depicted schematically in Figure 2.
  • Used material from a casting process is fed through a hopper 30 containing a drum magnet for removing pieces or metal. From there, the material passes down a chute 31 and via a valve 32 to a pressure vessel 33.
  • a pneumatic conveyor 34 extends from the pressure vessel 33 to a fluidised bed 35, and comprises an inlet pipe 36, a manifold 37 and a plurality of pneumatic lines 38 extending from the manifold 37.
  • Each line 38 is provided with a valve 39 for regulating the flow of material to the bed 35, and terminates at an injector 40 disposed at approximately the level of bubble caps (not shown) in the bed 35.
  • To one side or the bed 35 there is provided a cooler/classifier 41 to which material flows from the bed 35 over a weir (not shown). If desired, an after-bed (not shown) can be interposed between the bed 35 and the cooler/classifier 41.
  • the pressure vessel 33 is provided with a high level probe 42 and a low level probe 43.
  • the valve 32 is automatically shut off and the vessel is pressurised so that the material is then conveyed by the conveyor 34 into the lower part of the fluidised bed.
  • the vessel 33 is depressurised and the valve 32 is opened once again. In this way, the material is fed in batches from the vessel 33 to the bed 35.
  • the provision of the low level probe 43 prevents the mixture from being completely exhausted from the pneumatic conveyor 34 after each batch feed operation, so that hot sand from the bed 35 is prevented from running through the system and into the vessel 33 under the action of gravity.
  • the apparatus can also be provided with a charging or priming system which, as the bed is about to be shut down, allows clean sand to be fed into the vessel 33 and thence into the conveyor 34. In this way, it is ensured that these parts do not contain any bonding agent during shut down, which might otherwise cause rebonding of the sand and consequent clogging of the pneumatic conveyor.
  • foundry sand for reclamation is fed in batches to the fluidised bed.
  • a substantially continuous feed can be provided by arranging a series of pressure vessels and pneumatic conveyors in parallel.
  • one pressure vessel can be charged with material from the chute 31 at the same time as material from the other vessel is conveyed to the bed.
  • Reference numeral 44 designates a detector provided in the chute 31 to regulate the flow of the material to the vessel 33.
  • material will accumulate in the chute 31 waiting for the valve 32 to be re-opened. So long as the material is fed at a rate less than the maximum capacity of the system, the level of the material in the chute 31 will never rise as far as the detector 44 before the valve 32 re-opens and causes the level to drop once again. However, if the feed rate exceeds the maximum capacity of the system, then the level of the material in the chute will rise as far as the detector 44, and the latter will activate a control to cause feeding of the material to cease.
  • a further advantage of the method according to the invention is that the hopper from which material to be reclaimed is fed is not necessarily located above the level of the furnace. This enables the apparatus to be installed in a building with a relatively low roof or ceiling.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Processing Of Solid Wastes (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Working-Up Tar And Pitch (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)

Claims (8)

  1. Méthode de récupération thermique d'un matériau à partir d'un mélange de matériau et de matière combustible, dont ladite matière est incinérée en lit fluidisé, la méthode comportant la pulvérisation mécanique dudit mélange, le procédé de mélange de la poussière provenant du procédé de pulvérisation avec ledit mélange, et l'apport du mélange directement en partie inférieure du lit fluidisé.
  2. Méthode telle revendiquée à la revendication 1, selon laquelle ledit mélange est introduit dans le lit fluidisé depuis son niveau inférieur.
  3. Méthode telle revendiquée à la revendication 2, selon laquelle ledit mélange est introduit au moyen d'un convoyeur mécanique dans un espace restreint situé sous le lit fluidisé.
  4. Méthode telle revendiquée à la revendication 3, selon laquelle ledit mélange est introduit en continu dans l'espace restreint.
  5. Méthode telle revendiquée à la revendication 2, selon laquelle ledit mélange est apporté au lit fluidisé par un convoyeur pneumatique.
  6. Méthode telle revendiquée à l'une ou l'autre des revendications précédentes, selon laquelle le mélange est injecté dans le lit fluidisé essentiellement au même niveau qu'un mélange d'air fluidifiant/gaz.
  7. Méthode telle revendiquée à la revendication 5, selon laquelle ledit mélange est injecté en lots dans le lit fluidisé et une pluralité d'amenées est prévue avec un fonctionnement séquentiel.
  8. Méthode telle revendiquée à l'une ou l'autre des revendications précédentes, selon laquelle le matériau de base est le sable de fonderie.
EP91908839A 1990-05-11 1991-05-03 Procede de regeneration thermique Expired - Lifetime EP0482161B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB909010611A GB9010611D0 (en) 1990-05-11 1990-05-11 Thermal reclamation method and apparatus
GB9010611 1990-05-11
PCT/GB1991/000714 WO1991017848A1 (fr) 1990-05-11 1991-05-03 Procede et appareil de regeneration thermique

Publications (2)

Publication Number Publication Date
EP0482161A1 EP0482161A1 (fr) 1992-04-29
EP0482161B1 true EP0482161B1 (fr) 1995-04-19

Family

ID=10675837

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91908839A Expired - Lifetime EP0482161B1 (fr) 1990-05-11 1991-05-03 Procede de regeneration thermique

Country Status (6)

Country Link
EP (1) EP0482161B1 (fr)
AT (1) ATE121326T1 (fr)
DE (1) DE69109049T2 (fr)
ES (1) ES2071996T3 (fr)
GB (2) GB9010611D0 (fr)
WO (1) WO1991017848A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2680326B1 (fr) * 1991-08-14 1995-03-24 Fm Ind Procede, unite et installation de regeneration par calcination de sables de fonderie.
GB2263535B (en) * 1992-01-08 1995-07-12 Richards Eng Ltd Incineration apparatus
GB2264352A (en) * 1992-01-31 1993-08-25 Richards Eng Ltd Incineration apparatus
FR2696367B1 (fr) * 1992-10-07 1994-12-23 Fm Ind Procédé et installation de régénération de sables de fonderies hétérogènes.
GB2285119A (en) * 1993-12-21 1995-06-28 Boc Group Plc Oxygenated incinerator
GB9624340D0 (en) * 1996-11-22 1997-01-08 Foseco Int Sand reclamation

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB731923A (en) * 1951-09-21 1955-06-15 Dorr Co Process for the thermal treatment of finely divided solids
US3776150A (en) * 1972-03-06 1973-12-04 Awt Systems Inc Fluidized bed system for solid wastes
US4213938A (en) * 1976-03-29 1980-07-22 Robert Pyzel Fluid bed reactor
DE2814239C2 (de) * 1978-04-03 1985-11-14 Steag Ag, 4300 Essen Wirbelbettfeuerung für die Verbrennung von stückigem Brennstoff
GB2056048B (en) * 1979-07-19 1983-06-08 Richards Structural Steel Co L Handling and/or treatment of particulate materials
US4330502A (en) * 1980-06-16 1982-05-18 A. Ahlstrom Osakeyhtio Fluidized bed reactor
SE437722B (sv) * 1980-10-22 1985-03-11 Stal Laval Turbin Ab Virvelbeddsbrennkammare
DE3903604C1 (en) * 1989-02-08 1990-03-29 Siempelkamp Giesserei Gmbh & Co, 4150 Krefeld, De Process for regenerating moulding sand

Also Published As

Publication number Publication date
DE69109049T2 (de) 1995-08-31
WO1991017848A1 (fr) 1991-11-28
ES2071996T3 (es) 1995-07-01
ATE121326T1 (de) 1995-05-15
EP0482161A1 (fr) 1992-04-29
GB9010611D0 (en) 1990-07-04
GB2244939A (en) 1991-12-18
GB9109673D0 (en) 1991-06-26
DE69109049D1 (de) 1995-05-24
GB2244939B (en) 1993-12-08

Similar Documents

Publication Publication Date Title
US5271450A (en) Thermal reclamation method
EP0578641B1 (fr) Enrichissement des cendres volantes par brulage du charbon dans un lit fluidise barbotant sec
US5289920A (en) Process for thermically recovering old sands obtained in casting plants and for treating the dusts obtained during circulation of the sand
US5616296A (en) Waste management facility
US4346661A (en) Furnace for treating industrial wastes
US4821654A (en) Regeneration of bulk materials
KR20000062384A (ko) 순환식 유동층 증기 발생기의 연료 및 흡착제 공급 방법 및 장치
EP0482161B1 (fr) Procede de regeneration thermique
KR100245040B1 (ko) 합성수지류의 처리방법 및 그 장치
US5251684A (en) Method for controlling the oxidation and calcination of waste foundry sands
US6231638B1 (en) Process for producing metal from metal ores
KR930000092B1 (ko) 큐우폴라 또는 용광로에 첨가물을 공급하기 위한 방법 및 장치
US4423688A (en) Brush feeder for disposal of thermoplastic waste in a fluidized bed reactor
US6682705B1 (en) Method for conducting reactions in fluidized particle layers
US5110288A (en) Gravity flow thermal process for reclaiming foundry sand
US5165888A (en) Gravity flow thermal process for reclaiming foundry sand
WO1994020414A1 (fr) Production d'anhydride sulfureux a partir de soufre granulaire ou colloïdal
WO1996000365A1 (fr) Systeme de production de produits a base de cendre et d'energie a partir de dechets
JPH01121617A (ja) 産業廃棄物燃焼装置
JP3376229B2 (ja) タイヤ粉搬送方法
JPH0816526B2 (ja) 流動床式焼却炉における循環粒量の制御方法およびその装置
JPH11148626A (ja) 木屑焚き燃焼炉及び炉への木屑類供給方法
US3611543A (en) System for hot de-oiling and hot briquetting
WO1993015360A1 (fr) Appareil d'incineration
JPH04295507A (ja) 有害物質で負荷された廃棄物を再生する方法及び装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19920211

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

17Q First examination report despatched

Effective date: 19930929

RBV Designated contracting states (corrected)

Designated state(s): AT BE CH DE DK ES FR GR IT LI LU NL SE

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE DK ES FR GR IT LI LU NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRE;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.SCRIBED TIME-LIMIT

Effective date: 19950419

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19950419

Ref country code: AT

Effective date: 19950419

Ref country code: LI

Effective date: 19950419

Ref country code: CH

Effective date: 19950419

Ref country code: DK

Effective date: 19950419

Ref country code: BE

Effective date: 19950419

Ref country code: NL

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19950419

REF Corresponds to:

Ref document number: 121326

Country of ref document: AT

Date of ref document: 19950515

Kind code of ref document: T

REF Corresponds to:

Ref document number: 69109049

Country of ref document: DE

Date of ref document: 19950524

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19950531

REG Reference to a national code

Ref country code: ES

Ref legal event code: FG2A

Ref document number: 2071996

Country of ref document: ES

Kind code of ref document: T3

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19950719

ET Fr: translation filed
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: FR

Ref legal event code: TP

Ref country code: FR

Ref legal event code: CD

REG Reference to a national code

Ref country code: ES

Ref legal event code: PC2A

REG Reference to a national code

Ref country code: ES

Ref legal event code: PC2A

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20030508

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20030515

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: ES

Payment date: 20030529

Year of fee payment: 13

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040504

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20041201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050131

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 20040504