US2911671A - Apparatus for and method of handling molten furnace ash - Google Patents

Description

E. B. TOLMAN Nov. 10, 1959 APPARATUS FOR AND METHOD OF HANDLING MOLTEN FURNACE ASH I Filed Sept. 17, 1956 2 Sheets-Sheet 1 m m m m Nov. 10, 1959 E. B. TOLMAN $911,671

APPARATUS FOR AND METHOD OF HANDLING MOLTEN FURNACE ASH Filed Sept. 17, 1956 2 Sheets-Sheet 2 IN VEN TOR.

gglgarfi J5 Zmcm;

United States Patent APPARATUS FOR AND METHOD OF HANDLING MOLTEN FURNACE ASH Edgar B. Tolman, Winnetka, Ill., assignor to United Conveyor Corporation, a corporation of Illinois Application September 17, 1956, Serial No. 610,104 6 Claims. (Cl. 18-2.4)

This invention relates to a method of and apparatus for handling molten furnace ash.

In burning coal, it is now common practice to grind the coal to a powder and blow it into the furnace of the modern boiler with the necessary air for combustion. It is also common practice to maintain the temperature ber 10 is supported on legs 18, and has a top wall 19 in the firing section of the furnace above the melting temperature of the ash in the coal. The ash then drains out of the furnace bottom in a molten state.

In accordance with the present invention, the molten is permitted to drop into a quenching water bath which solidifies the ash into slag. Under normal conditions, the slag automatically forms a coarse, granular material which may be readily moved in a water sluice conveyor. However, under certain conditions and, particularly, with certain types of coal, various problems arise in the handling of the molten ash, as follows:

(1) The molten ash will vary in its consistency over a large range. It also will vary in the melting rate and, therefore, in the rate of discharge to the quenching tank. When there is a rapid rate of discharge of very heavy molten ash it will pass through the water to the bottom of the tank before it solidifies. When this occurs the removal of this material can only be accomplished with a great amount of manual labor.

(2) Under some conditions a considerable percentage of the molten ash upon striking the water forms into a porous slag which floats on the surface. If this floating slag is allowed to accumulate the subsequent flow of ash will build up on it and choke off the discharge neck from the furnace. There seems to be no way of telling when this material will form, or the rate of formation. Therefore, it is desirable to remove it at a continuous rate.

In accordance with the present invention, the water in the quenching bath is violently agitated so as to break up the molten ash and prevent it from forming into unmanageable masses. This may best be accomplished by the use of high pressure water jets which discharge into the bath immediately adjacent the surface.

Further to improve the handling of the slag which forms in the quenching bath, the quenching bath chamber is provided with an overflow valve near the top and a drain valve near the bottom; and the high pressure nozzles are arranged in three banks with provision to admit water to the nozzles in the various banks sequentially so that only the nozzles in a bank close adjacent the surface of the water in the bath are in operation at any given time. Then, by proper coordination of the overflow gate and the drain gate, the water level in the quenching bath may be caused to rise and fall cyclically, with surface water containing floating slag being removed through the overflow gate at the top of a cycle and water from the bottom of the bath containing heavy slag being removed through the drain gate during a cycle of falling water after the overflow gate is closed.

To assure that the slag is of suitable size for easy handling in a water sluice conveyor, both the floating slag R. 2,911,671 Ice Patented Nov. 10, 1959 and the heavy slag is passedthrough a grinder, after leaving the quenching chamber, which pulverizes it to a maximum size.

The apparatus of the invention is illustrated in a preferred embodiment in the accompanying drawings in which:

Fig. l is a side elevational view of a device constructed in accordance with the invention, partially in section; and

Fig. 2 is a section taken as indicated along the line 2-2 of Fig. 1.

Referring to the drawings in greater detail, a quenching bath chamber, indicated generally at 10, is provided with upright end walls 11, side walls 12, and inclined bottom walls 13, 14, 15, and 16, which converge upon a relatively small base 17. The quenching bath chamwhich is provided with a pair of molten ash inlets 20. Each inlet 20 is just beneath a discharge opening 21 of a furnace, and a suitable water seal trough 22 surrounds each ash entrance 20 and furnace opening 21 to permit relative expansion and contraction of the furnace with respect to the chamber and to seal the furnace pressure from the atmospheric pressure.

In the end walls 11 of the chamber 10 is a plurality of high pressure water nozzles arranged in three vertically-spaced banks, the nozzles in the uppermost bank being indicated by the reference numeral 23, those in the intermediate bank as 24, and those in the lowermost bank as 25. The nozzles of each bank are connected with a high pressure water source.

As best seen in Fig. 2, in one of the side walls 12 of the chamber 10 is an overflow opening 26 provided with a normally closed overflow control gate 27 which is connected by a suitable linkage 28 to a hydraulic actuating mechanism 29 by means of which the overflow gate may be automatically opened and closed. The overflow opening 26 communicates with a duct 30, the lower end of which opens into a discharge enclosure 31 which is mounted on the inclined lower wall 16 immediately adjacent the bottom of the chamber.

The inclined bottom wall 16 of the chamber 10 is provided near the lowerend with a drain opening 32 having a normally closed drain gate 33 which is connected by a suitable linkage 34 with a hydraulic unit 35 by means of which the drain gate may be selectively opened or closed. When the drain gate is open, water and heavy slag from the bottom of the chamber may pass through the opening 32 into the discharge enclosure 31. From enclosure 31, water and floating slag from overflow opening 26, or water and heavy slag from drain opening 32, passes through a pulverizing grinder 36 to a Water sluice conveyor 37. As seen in Fig. 1, an electric motor 38 is provided to operate the grinder 36 through a suitable driving connection 39.

As shown in broken lines in Fig. 2, to assure that there will be no breakdown of the ash handling unit, the entire device may be provided with duplicate slag discharge and control elements. Thus, shown at the lefthand side of Fig. 2 in broken lines is an alternative discharge duct 30a to receive floating slag and water from an overflow opening (not shown) and an additional discharge enclosure 31a, with an alternative drain gate 33a which controls passage of water to the discharge enclosure 31a from a drain opening 32a.

The water level, and the operation of the Water jets in the banks 23, 24 and 25 is controlled by a' suitable commercially available water level control device 40. Basically, all such control devices utilize a buoyant object to actuate a valve, either directly or through an electric switch or pressure mechanism; so as to accomplish a desired result at a predetermined level of liquid in a vessel. Since the specific means for producing the desired valve operation is no part of the present invention, and many mechanisms for accomplishing the necessary operations are familiar to engineers and commercially available, no detail of themechanism is given.

The drawings are providedwitli'four broken, horizon.- taLlines, of which the line A indicates the top level of water in the chamber, the line D" indicates the bottom' level, while the lines B and C indicate two intermediate levels at which certain changes 'in operation take place.

Assuming that the water is rising between the level B and the level A, the nozzles in the bank 23 are operating to agitate the water, ar'1d both the, overflow gate 27 and the drain gate 33 are closed. Whenjth'e water level reaches thelin'e A suitable [automatic controls actuate the hydraulicunit Z9 1to open the overflow gate 27 and permit surface waterj 'fioating s'lagand suspendedislag in the uppermost portion of the water, to pass out the overflow opening 26; into thelduct 30, through the discharge enclosure 31, through: the pulverizing grinder 36 and info the water" sluice conveyor37. Discharge of water through "the" overflow opening 26 is much more rapid than admission of water through. the bank 'ofuozzles '23, so the water levelfc'ommences to fall. At the intermediate level B; which is flush with the lower margin of the overflow opening 26 the con: trols automatically produce three'changes in' the functioning of the device; Thehydraulie meehanism 29 is operated to close theoverflow gat e.27, the hydraulic mechanism 35 is operated to open the drain gate 33,"and the flow of water is transferred from the topibank of nozzles 23 to the intermediate bankof nozzles 24. The size of the drain opening 32 is such that the level of Water continues to drop in spite of the admission" of water to the chamber through the bank'of nozzle's 24; and the water in the bottom of the chamber which passes out through the drain opening 32, carries heavy slag into the discharge enclosure 31 and through the pulverizing grinder 36 into thewater sluice conveyor 37, Thus, all the water and slag is directed into a common discharge path after it leaves the chamber, and the slag is pulverized as it moves through "said p'ath.

The water level continues to fall until, .at the intermediate level C the flow of water throughj the bank of nozzles '24, stops and flow ofwaterj through the lowermost bank of nozzlee'ZS starts. The water level'driops to the lowermost: line D at'which point an autc ma'tic control operates the hydraulic mechanism 35 to close the drain gate 33, so that the waterle'vel again beginsto rise'in the chamber. As the level moves upfrom D to A, the inflow throughthe nozzles changes at the level C from the nozzles 25 to the nozzles 24fand at the level B from the 'nozzles 24 to' the nozzles 23. The device continues to operate through successive cycles of rising and falling Wateras just described as long as it is in operation. During the entire dischargeQfrom the overflow opening 26 and from the' drain opening 32, the pulverizing grinder 36 is in operation so asjto grind both the floating slag and the heavy slag and assure that it is of suitable fineness to be handled readily' in the water sluice conveyor 37.

The present system has several advantages in addition to those previously enumerated, For one'thing, all the water which enters thequenching bath chamber 10. passes out through the water sluice conveyor 37. to the point of disposal, so thatthere is no 'overflowof water requiringthe use 'of a' sump'purnp. This is a considerable practical advantage, because thebverflo'w water jordinari 1y contains some fine, but'abrasive, sla'gflwhich causes very rapid deterioration of a"sump pump. Naturally, it also eliminates the need for apsump pump and. the power required to operate'it. i

The present systemalso may be coupled with a means for removing the flyash; orpowderyjash; which goes out of the furnace with the stack gases', The vpow der yl ash must be collected in dust collectors; and where the present apparatus is installed, the ash from the dust collectors may be conveyed to a central point where it is mixed with Water and discharged into the quenching bath chamber 10 through the high pressure nozzles. This permits the same water to be used both for fly ash removal and for slag removal.

The foregoing detailed description is givenfor clearness of understanding only and nd unnecessary limitations are to be understood therefrom, as some modifications will be obvious to those. skilledrin theart.

I claim:

1. Apparatus for. handling molten furnace ash which dischargescontinuously" from a furnace, comprising: a chamber containing aiquerichingwat er bath; means for dropping molten furnace ash into said bath; high pressure water jet means for continuously admitting water to the bathto violently agitate thewater adjacent the surface ofthe bath and thusibreak the .molten ash into relatively small pieces as it solidifies in the bath to form slag; an overflow outlet for water containing floating material; a normally closed overflow gate controlling said overflow outlet; a bottom drain outlet for. water containing heavy material; a normally closed drain gate controlling said drain outlet, each of said outlets having a discharge rate substantially in excess of the. rate of admission of waterato the bath through. said .jet means; automaticcontrol means for said gates to cyclically open the overflow gate when the water level in the bath reaches a toplevel above the bottom of said gate, then close said overflow gate and open the drain gatewhen the water level reaches the bottom of the. overflowoutlet to produce a continuous, discharge. in which" the water level drops substantially below said overflow outlet, and to thereafter close the draingat e when: the water reaches a bottom lvel'above theQdrain gate to again raise the level of water to the maximum level, whereby floating slag and heavy slag may beaIternateIy removed from the bath'through the overflow outlet and the drain outlet, respectively; and water sluice: conveyor means through which water and slag are carried away from said outlets.

2. The apparatus of claim 11 in which the water jet means comprisesa plurality'of vertically spaced banks of nozzlejs,','the iippermostbank immediately adjacent the top water level and the lowefi-ndstbank beingdimniediately adjacentlthe bottomiwaterlevel, and which includes automatic 'control' means. for fad mittir ig water tothe chamber only through'thefnozzlesfin a bank which is immediately adjacent thefsurface .of the bath at any given time. i

3. The apparatus of claim 1 which includes, a discharge enclosure communicating with both outlets, and a pulverizing grinder communicating with the discharge enclosure and'with the water sluice conveyor means.

4. The apparatus of claim 3 in which the discharge enclosure 'is immediately adjacent the drain outlet and a duct communicates with the overflow outlet and said enclosure. l

5. The method of handling molten furnace ash which discharges continuously from a furnace, said method in cluding the steps of quenching the ash in a water bath to form slag whilecontinuously agitating thewater in the. bath by means of high pressurewater jet streams which discharge adjacent the surface of water in the bath .to prevent slag agglomeration; cyclically draining water fromthe bottom of. the bath to remove heavy slag,'a nd then raisingthe level of water in the bath to produce a lateral overflow of water which carries off floating'fslag; directing all the water and slag removed from the bath into a common discharge path; and grinding all said slag to eliminate oversize pieces as it moves through said vpath.

6. The method of handling, molten furnace ash which discharges continuously from a furnace, said method:

including the steps of quenching the ash in a water bath to form slag while continuously agitating the water in the bath by means of high pressure water jet streams which discharge adjacent the surface of water in the bath to prevent slag agglomeration; cyclically draining water from the bottom of the bath to remove heavy slag, and then raising the level of water in the bath to produce a lateral overflow of water which carries oif floating slag; and directing all the Water and slag removed from the bath into a common discharge path.

References Cited in the file of this patent UNITED STATES PATENTS 512,761 Stalmann Jan. 16, 1894 6 Clark June 26, Duncan Oct. 13, Elmore Mar. 19, Gorsuch June 28, Schott Mar. 7, Cross June 25, Newton May 5, Dolezal May 31,

FOREIGN PATENTS Great Britain May 15,

Images