IL43490A

IL43490A - Furnace for burning liquid waste

Info

Publication number: IL43490A
Application number: IL43490A
Authority: IL
Original assignee: Lucas Furnace Dev Ltd
Priority date: 1972-10-26
Filing date: 1973-10-26
Publication date: 1977-01-31
Also published as: ATA904773A; FR2204781B1; FR2204781A1; NO134717C; TR17639A; US3799074A; BR7308398D0; AR198009A1; NO134717B; BE806282A; AU6132073A; ZA738285B

Description

furnace This invention relates to furnaces for burning liquid waste such as sewage and like British Patent discloses a furnace burning liquid waste in which the liquid is fed into a furnace having hearth so that the liquid a pool on the the diameter of the pool being the same as the In the furnace is used to burn liquids of both high and low calorific values and to control the rate of the rate of supply of liquid to the furnace has to be carefully especially in the case of liquids of high calorific The object of the present invention is to provide a furnace for burning liquid waste in which the hearth is specially designed to facilitate control of the rate of combustion of the liquid In accordance with the invention there is provided a furnace for burning liquid waste comprising a combustion having a hearth which comprises a conical an inlet for liquid to be said inlet being arranged to deliver liquid to said a plurality of fuel burners arranged around the and all directed generally tangentially and downwardly to direct flame and combustion products towards liquid on said hearth and to set up cyclonic of combustion and an exhaust outlet disposed above said burners so that evaporated liquid waste and products of combustion pass through a high temperature zone in travel to the outlet when the burners are said chamber including a conical cyclone area located between said burners and outlet for creating a final combustion In there are two different possibilities provided by the The liquid may be confined as a pool on the so that the surface area of the pool is available for evaporation and for combustion of the liquid and where this is the the liquid may be supplied through the hearth from via a central pipe communicating with the lowest point of the or the inner and steeper of the where two different angle cones are In this the surface area available will depend upon the depth of the liquid in the and this may be regulatcn according to the value of the liquid as a the liquid may be burnt as a thin film trickling down the slope of the and may be fed in a plurality of streams from the outer periphery of the hearth for this In such the flow rate may arranged that the liquid is wholly combusted before it reaches the central area of the hearth and the latter may serve as an ash pit for incombustible feed around the periphery of the hearth may also be used to maintain a pool on the hearth for combustion and evaporation from the surface of the pool as in the first mentioned Where it is the intention to maintain a pool on the and where feed is through a central point from below the the level may be controlled by supply from a tank having a weir plate to control the height of liquid in the tank and with of from the weir and hence the height of the top of the weir plate and the surface of tho pool may be maintained equal by gravity and in either that is whether it a thin film trickling clown which is being burnt or the surface of the pool which is being the flow may be under the control of pumps which may be adjusted either manually or the latter under the control of sensors reading the temperature of the exhaust gases from the furnace or the percentage of carbon dioxide Two embodiments of the present invention are now more particularly described with reference to the accompanying drawings wherein FIGURE 1 is a elevation of a typical furnace installation according to a first FIGURE 2 is a diagrammatic sectional elevation showing the feed and with other parts omitted for of the first FIGURE a view similar to Figure but showing the feed arrangements according to a second and FIGURE 4 is a plan view of the arrangement of Figure 3 Referring now to the and particularly Fi ures 1 and 2 the furnace comprises a combustion chamber 10 which is generally cylindrical and has a hearth 12 at the lower end of the the axis of the cylinder being vertically The hearth includes a shallow area 14 opening to a steeper central portion or well 16 in the of Figures 1 and communicatee to a delivery pipe The upper end of the furnace combustion chamber is provided with a cyclone area 20 with exhaust passage 22 connected to a flue and possibly or wot extractor t e c with before being connected to the final outlet flue or chimney The whole of the interior of the combustion chamber area of the furnace is lined with refractory such as silicon and a plurality of oil or gas burners 32 open into combustion being downwardly directed and tangentially inclined to the periphery of the so as to induce action of combustion A plurality of combustion air inlets are also which may be combined with the burners or separate which in the latter case will be similarly The burners may be adjustable in to enable flame to be directed at the Considering now particularly Figure 2 of the drawings waste liquid is stored in tank 40 and fed via pump 42 to final tank 44 which includes a weir plate 46 which is adjustable in height so that surplus liquid in tank 44 spills over into portion from whence it is recirculated by pump 50 to return to the tank The height in the tank 44 is therefore predetermined and and the liquid is fed by gravity along pipe 52 to inlet 18 and hence into the The height of the surface of the pool confined in the furnace is fore substantially the same as the height of the top of the weir plate In if industrial wastes of substantial calorific value are being a pool of relatively small surface area will be obtained by lowering the weir plate possibly until the pool is confined within the steeper The rate of burnii is then likely to be limited only in order to prevent overheating of the furnace and such the burners may be operated at rate only in order to maintain the combustion and ensure that the combustion products pass the burne on to the particularly If the liquid waste being burnt is of a lower calorific in general it will be preferred to provide a pool of larger surface and the weir plate will be rained In such and particularly with very low value materials the burners will operate at a higher rating in order to maintain combustion at desired It is possible to vary the angles of the from one design of furnace to and in order to suit particular but it has been found experimental y that the use of the two cones of different angles substantially avoids the need for for the narrower angle portion is suitable for high fuel value wastes and the wider angle cone for low and more critical and efficient control is possible by these means would be the case for a single cone were In all and even where the calorific value is sufficient to enable the burners to be shut combustion air continues to be supplied into the furnace in the tangential and wardly directed manner which ensures high efficiency vortex and hence completion of combustion within the cylindrical area of the the final also serving to maintain the vortex and complete the In the cases of the low calorific value for example watery the heat generated maintains and particles entrained in the evaporating vapours are thoroughly mixed with flame in the vortex and essentially pass through the burner flames before reaching the final again for the purposes of ensuring thorough and complete combustion of the of n stand pipe 18 which forms an ash for incombustible residues which are not carried off in the combustion products for subsequent In this a ring main or manifold 60 extends around the periphery of the but externally above the furnace and a plurality of separate inlets 62 extend through th cylindrical wall to deliver liquid to substantial the periphery of the hearth so that the liquid trickles down towards the central The inlets 62 may bo provided with divergent nozzles or tures so as to spread the liquid over substantially the whole of the surface area of the In the arrangement of Figures 3 and there is trated a tank to pump 72 which delivers to the with valve controlled enabling the pump to be run at constant but for the delivery rate to be controlled in dance with The arrangement of Figures 3 and may be operated so that the liquid waste material through the inlets 62 and trickling over the hearth is all evaporated and burnt by the burnere and combustion air via the inlets therefore not shown before it reaches the central and steeper portion 16 so that there is no true pool of liquid on the the same arrangement may be usod to feed a pool of with possibility of some fraction of the liquid waste material evaporating or burning off before it reaches the is to say providing a pool which is of smaller diameter than the Ash or other incombustible residue may be removed from the outlet 18 as and when In any of the arrangements or systems the temperature of the gases leaving tho furnace may be sensed and used rising temperature above a predetermined maximum will be effective to cause reduction of the feed an the carbon dioxide content of the exhaust gases may be and used control feed and the particular method selected assuming that manual operation is not required may depend upon the nature of the waste material to be according to the invention may also be suitable for the combustion of liquids containing sodium or other materials which would normally attack the refractory lining of the and for such purposes the hearth may be composed of a especially a high temperature alloy In such event it is preferred to maintain the hearth surface wot with the liquid over its entire surface or substantially and hence it preferred to feed liquid to the periphery of the the Figures version is preferred to the Figures 1 and 2 The waste liquid then has the mentary purpose of maintaining the hearth Preferably for such an annular weir is provided as a vortical extension of the liearth periphery and the weir forms one wall of a channel or trough fed from an external reservoir by gravity from a system such as in Figure so that the liquid spills over at a plurality of points to feed the pool on the hearth or burn on the surface of the The annular weir may be of formation or like to ensure that feeding occurs around the whole of the periphery the insufficientOCRQuality

Claims

1. Λ furnace for burning liquid waste comprising having a hearth which comprises a frusto-conical area, to be bujjnt, said inlet being arranged -to deliver liquid to said hearth, a plurality of fuel burners arranged around the chamber and all directed generally tangentially and downwardly to direct flame and combustion products towards liquid on said hearth and to set up cyclonic action of combustion products, and an exhaust outlet disposed above said burners so that evaporated liquid waste and products of combustion pass t?n ^ h a high temperature zone in travel to the outlet when the burners are operating, said chamber including a conical cyclone area located between said burners and outlet for creating a final combustion vortex.

2. A furnace as claimed in Claim 1 wherein said hearth comprises a shallow outer frusto-conical area surrounding a central steeper-angle frusto-conica portion.

3. · A furnace as claimed in- Claim -1·; or Claim 2, in which' the inlet is located centrally of the hearth.

4. A furnace as claimed in Claim 1, or Claim 2, in which there are a plural ity of said inlets each located adjacent the outer periphery of the hearth and' arranged to direct liquid over the hearth and towards the centre thereo

5. A method of burning liquid waste in a furnace constructed in accordance with any one of Claims.1-3 comprising confining a pool of the liquid on the hearth.

6. A method of burning liquid waste in a furnace constructed in accordance with either one of Claims 1 and 2 comprising feeding the liquid to the oute as periphery of the hearth to trickle down the hearth and bum a film on the hearth surface.

7. · A furnace as claimed in Claim 3 and arranged to operate in. accordance with Claim 5? wherein liquid waste is delivered to the hearth via said cent rally located inlet and the depth of the pool of liquid is controlled in order to maintain the. required surface area of the pool in accordance with the calorific value of the liquid.

8. A furnace as claimed in Claim 7 wherein the liquid is fed by gravit from a tank in which the height of liquid is controlled by an adjustable weir plate.

9. A furnace as claimed in Claim 8 wherein the height of the weir plat is controlled by one or more sensors which are affected by furnace interior conditions.

10. A furnace as claimed in any one of Claims 1-4 and arranged to oper ate in accordance with Claim 5 or 6, wherein liquid waste is delivered to the furnace via said inlet or inlets by a pump and the delivery rat is adjusted in accordance with furnace interior conditions as detected by one or more sensors.

11. A furnace as- claimed in any one of Claims 1, 2, 4 or 10 and arrang to operate in accordance"with.Claim -5 or 6; wherein a ring 'main. surrou the hearth and a plurality of said inlets open to the periphery of the hearth from the main. For the Applicants DR. HOLD CQH AND PARTNERS