US2365305A - Waste heat boiler - Google Patents

Description

Dec. 19, 1944. C, E sTROMQUlST 2,365,305

WASTE HEAT BOILER 'Filed Jan. 24, 1941 4 Sheets-Sheet l 2; K au Dec. 19, 1944 c. E. sTRoMQUlsT 2,365,305 WASTE HEAT BOILER Filed Jan. 24, 1941 4 sheets-sheet 2 11E. E. 67 i @5 70 @y ./Umdm C T Teo/MWST, y,

c. E. s TRoMQuls-r WASTE HEAT BOILER Filed Jan. 24; 1941 4 Sheets-Sheet 5 1j; f/ FIEJl C. E. STROMQUIST Dec. 19, 1944.

WASTE HEAT BILER 4 sheets-sheet 4Y Filed Jan. 24, 1941 liwenfo C f. 57790 tained in ,thewaste gases;

Patented Dec. 19, 1944 l f UNITED STATE s PATENT onf-Ici?.

i WASTE HEAT BoILER v Carl E. Stromquist, Grimth, v Application January 24, 1941,l Serial No.v3r75,862'

.s Claims. A(01,5.122-7') 'l .My invention aims to yprovide'fa waste heat steam boiler specially designed for use 'in conrnection with cement kilns, with accessoryA appa- .products of combustion of the fuel used in calcining the. raw materials, composed of limestone,

clay, slag, etc., contain'a considerable amount of dust evolved from the raw materials. This hot dust is tenacious or abrasive, or both, depending on the composition of the raw materials used, and therefore tends to adhere to the boiler surfaces and also to wear away the metal at zones of. high velocity. Conventional types4 of boilers and apparatus-used for generating steam by burning of fueldirectly under the boilers have been heretofore slightly altered in attempts to adapt them for use as waste heat boilers. lThis resulted in considerable difficulty caused by the ldust accumulation on the boiler surfaces, thus obstructing'l the iiow of gases,`interfering with the draft, and by dust 'eventually wearing holes in the boiler tubes, thus requiring costly premature replacements and repairs. I

Boilers of the prior art that have previously been designed for waste heat service either lack certain essential features or contain certain objectionable vfeatures and have therefore not `proven entirely satisfactory in actual service.

. pended claims, to provide a workable installation which overcomes the above mentioned deficiencies which are inherent in prior art installations.` The essential features of a successful waste vention will be readily understood from a Aconsideration of the appended claims when read in connection with the following specification and the accompanying drawings, in which:

' Figure 1 is a longitudinal vertical view of the boiler (just inside of the brick sidewall) Figure 2 is a transverse vertical section taken along the plane of the line II'-II of Figure 1;

" v FLC-iure 44'is an'enlarged lfmgitudnal View of the v lower portion of the boiler;

Figure 5 is a transverse section of Figure taken along line V-V;

` lFigure 5a is a detailof a `portionoffthe soot blowing apparatus;

45 heat boiler apparatus embodying the present iny Figure 6 is an isometric view takenfrom the right end of Figure 1 showinga `portion of the economzer andillustrating the course of the water circulation. n

To obtain practical and workable results in the operation of a waste .heat boiler tobe used in vconnection with a cement kiln, .the principal Ves sential features embodied in my invention are as follows;

Firstthe vutilization of straight vertical boiler u. tubes, economizer tubes, and superheater tubes.

f ...Second-the provision of a sectional s tube header. This is to facilitate the dislodgement of 4dustl from the lower headers and to permit access to the entire area of all tubes by means of lancing apparatus entered between the upper headers.

`.Third--the provision of means to induce a rapid water circulation. Water circulation is ac.. celerated by means of downcomer. tubes,y located outside o f the direct gas passage. Thisl provides a rapid equalization of temperature of all surfaces of the boiler correspondingv with the developed pressure when quickly subjected to the heat of the incoming gas discharged from the kiln, thus eliminating excessive strain from unequal expansion.)v This also eliminates local circulation apparatus. The usual type of mechanical sootl blowers are inadequate for properlydislodging'the l dust in waste heat boilers used in connection with ycement kilns.

tus are provided to facilitate control of and dis. posal of dust. y

Referring now tothe drawings, in Figure 1 the Figure 3 is a plan of front portion of the boiler; 55 numeral I0 represents a rotary cement kiln sup- K hich the rising steam bubbles restrict 'l Inmy invention. special appara.'

,"'theupper header 59,"throug`h theu upper connecting "nipples (R andL) 6| "into the first compart ment of the upperwater boxes (Rand L) 55.1 'Ifhe b'aliles (R andL) '56 deflect the water through "the downcomer tubes (Rand L) and'5IA, into the rst and second compartments, respectively, ofthe lower connecting" boxes 52. The portion of the water descending through the downcomer tubes (R and L)` 5I re-enters the lower header 58 through the connecting nipples (R and L) 54 and recirculates upward through the heating tubes 50. The portion. of the water descending through the downcomer tubes (R and L) 5 IA into the second compartment of the lower water boxes (R and L) 52 passes through connecting nipples (R and L) 54A and 54B into headers I58A and 58B, then upward through heating tubes 50A and 50B, into the upper headers 59A and 59B. The Water in the header 59A passes through connecting nipples (R and L) BIA into the first compartment of the water boxes (R and L) 55, through downcomer tubes (R and L) 5|A and recirculates. The water in header '59B passes through connecting nipples (Rand L) GIB into the second .compartment of the water boxes (R and L) 55 and into downcomer tubes (R and L) 5|B and`5IC. The water in downcomer tube EIB recirculates through the lower headers 58B and heating tubes 50B. The water in downcomer tube 5|C enters the third compartment of the lower water boxes (R and L)- 52 and through connecting nipples (R and L) 54 into headers 58C,I then up through heating tubes '59C into header 59C. The water circulation thus continues successively through the remaining sections of the economizer until it leaves through the economizer outlet pipe v62.

The above described means for recirculation of water in an economizer is a novel arrangement which greatly increases the rate of heat transfer over the conventional type of economizer.

The baffles 5B, 55A, 56B, etc., are provided with respective bypass openings `51, 51A, etc. which may be termed leak holes which are effective to prevent vapor binding in the upper economizer water boxes 55. The water leaves the economizer through the outlet pipe 62 as shown in Figure 1. The required amount of water to maintain the proper level in the boiler is fed through the pipes S2 and 53 (Figure 1) and the feed water` regulator 64 into the boiler drum 38. With the boiler in normal operation, since the incoming water is of a lower temperature than that in the boiler, it will immediately flow down through the downcomer tubes 29 into the lower water boxes'22 (which are embedded in the boiler wall as shown in Figure 2), thence through the lower connecting nipples 25, headers I 4, into the steam generating tubes I3, upper headers 3| and upper waterboxes 30, where the steam bubbles are drawn towards the drum 38 and liberated into the steam space. The circulation is continuous through the individual sectional headers and corresponding downcomer tubes, thereby always Y entire boiler.

The steam leaving the drum 38 passes through a separator 85, thence through the separator outlet pipe 66, superheater inlet header 40. tubes 39 and the usual stop and check valve 61 to the steam main. The economizer, boiler, and superjand 2.

-heateri arc i, withf'conventional `'safety ,'69,` and 'I0 'inFigures 1 i valves as indicated'at' 6 8 The gas` travelisi'in a' single pass, impinging A' on th.front bankof thefsteam generating tubes I3, vthe superheater tubes 39, the rear bank of the boilerv tubes I3, and the economizer' tubes 50, thence discharged through the induced draft fan 1|.

In installations where the dust conditions permit, baiiies are inserted between certain rows of tubes in the rear zone of .the boiler and in the economizer to increase gas velocity. Also, where y dust conditions permit, the tubes are staggered skilled in the art without departure from the invention as defined in the appended claims.

I claim:

1. 'A boiler adapted for direct connection with a kiln or furnace, for utilizing waste heat gases and products of combustion, including upper and lower water boxes connected-by downcomer tubes, lower headers communicating therewith, upright tubes communicating with the lower headers, a supporting structure, and a lubricating plate on which the water boxes and the lower headers bear, said plate having passages therein withy openings extending to the surfaces on which the water boxes and headers bear, and a, tting to facilitate the introduction o-f a lubricant through said passages whereby the water boxes and headers are supportedwith freedom to permit the same to move relatively to one another under the inuence of expansion and contraction due to temperature variations.

2. A boiler adapted for direct connection with a kiln or furnace, for utilizing waste heat gases and products of combustion, said boiler comprisin-g a steam drum, a pair of spaced upper water boxes communicating with the drum at its opposite ends, a pair of lower water boxes connected with the upper water boxes by respective downcomer tubes shielded by being enclosed in respective walls, a series of upper headers connecting said upper water boxes, a plurality of sets of vvertically spaced lower headers spanning theA space between said lower water boxes and communicating therewith at different elevations, and respective sets of straight vertical boiler tubes connecting the said several lower headers with the said several upper headers, the vertical spaclower horizontal water boxes connected with said upper boxes by respective straight vertical downcomer tubes shielded by being enclosed in re-

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