US2254373A - Water tube steam boiler - Google Patents

Description

Sept; 2, 1941. LANGVAND 2,254,373

WATER TUBE STEAM BOILER Filed June 15, 1938 3 Sheets-Sheet 1 Sept. 2, 1941.

l. L. LANGVAND 2,254,373

WATER TUBE STEAM BOILER Filed June 15, 1938 3 Sheets-Sheet 2 1 v gill/III], II 1111/ 1N VENT OR.

cyzfar [anyz/and P 1941- l. L. LANGVAND 2,254,373

WATER TI JBE STEAM BOILER Filed June 15, 1938 3 Shets-Sheet 3 INVENTOR. cyl az" [,cznyi cm ATTORNEY.

Patented Sept. 2, 194 1 I 12,254.31: WATER TUBE STEAM BOILER Y Ilvar humane. Babel-ton, .omo, minor to The Babcock & Wilcox Company, Newark, N. 1,, a corporation of New Jersey Application June 15, marksman No. 213,753

4 Claims. (01. 122 480) This invention relates to improvements in fluid heat exchange apparatus, and it is more particularly concerned with the control of superheat in the operation of a high pressure and super- 7 heat water tube steam boiler.

The invention is particularly concerned with the maintenance of superheat within close limits under conditions which involve widely varying boiler loads, and the steam boiler with which the invention is concerned involves upright steam tion through-an illustrative installation. This view shows a 4-drum boiler with upright tubes Inthedrawings: J

Fig. l is a view in the nature of 'a vertical secand with bafiies arranged to provide for the flow of the furnace gases over the tubes and in a plur'ality of passes. These baiiles also provide for the flow of furnace gases through a superheater bypass in which there are disposed parts of the generating tubes arranged in one of more banks and connected to upper and lower drums. A. superheater including spaced tubes, receives steam generated in said banks of tubes and subjects it to the heat from furnace gases. It is one objector the invention to provide such improvements in apparatus of this type that the requirements of modern high pressure and" high temperature steam power plants may be effectively. met. Such installations, in the interest of high efficiencies of associated prime movers, operate at high superheats, and, as the associated steam turbines are apt tobe damaged by uncontrolled and excessively wide variations in steam temperatures, it is important that such-variations be controlled and limited. A more specific object of the invention is to provide a particular means for regulating and limiting such variations in superheat in this type of boiler.

For high superheats, and especially for steam generators in which there is a high ratio of heat of superheat to heat of steam generation, a relatively large superheater tube surface is necessary, but excessive superheater costs are avoided, and the desired high superheats are obtained by locating the superheater in gas zones in which the temperatures "are as high as practical consistent with safe metal temperatures and with thedesired conditions of non-adherence of the particles of slag crash suspended in the furnace gases. The invention also provides improvements whereby a superheater is adequately screened from the radiant heat of the furnace. in the interest of avoiding tube damagedue to overheating by such radiant heat.

The invention also provides means for bypassing furnace gases about superheater surface in order to reduce heat input and control final steam temperature. This means is especially adapted for a 4-drum Stilring type boiler.

Other objects of the invention will appear from the following description referring to the accompanying drawings showing preferred embodiments of the invention.

steam generating tubes adjacent the submerged water chamber;

Fig. 2 is a vertical section-of another embodiment'of the invention:

Fig. 3 is adiagrammatic view in the nature of a vertical section showing apparatus for controlling the damper;

Fig. 4 is a transverse section taken on the line 4-4 of Fig. 3; and

Fig; 5 is a detail view in-the nature of a transverse section through a part of the damper control mechanism. This view is taken on the line 5-5 of Fig. 3.

In the drawings, Fig. 1 illustrates a 4-drum bent tube boiler in which the submerged drum I0 is connected to the upper drums l2, It, and It by three spaced banks of tubes. The tubes of the front bank l8 directly connect the drums l0 and I2 and are exposed to the heat of the furnace IS. The tubes of the middle bank 20 di- -rectly connect the drums l0 and H and are disposed in a second gas pass in which the furnace gases pass downwardly over those tubes. A third pass, idle in so far as heat absorption is concemed, is incorporated in the installation to provide for the gas flow regulation hereinafter described. All of the tubes of the rear bank with the exception of the tubes of its foremost row are disposed in a fourth gas pass. The rearward tubes of this bank directly connect the drums l0 and it, while the remainder of the tubes of the bank directly connect the drums wand II.

A superheater 22, disposed between the tube banks It and 20, receives steam from the drum I6 through the intermediary of the saturated steam supply tubes 24 and the superheater inlet header 26. The superheater is contacted by the hot gases from the furnace I! which may be I fired by pulverized coal burners, and superheated steam passes from the superheater tubes to the superheater outlet header 28 and then'to a point of use.

Furnace gases, after, passing over the steam generating tubes l8 and the tubes of the superheater 22, turn downwardly around the upper edge of the baiiie 30 which is preferably post.-

2 i ass-1.37s

I tends downwardly to the regulator 00.

At a position somewhat above the submerged drum I the by-pass bailie 40 extends from the lower end of the baiile 80 across the tubes of the bank 20 and then along parts of the tubes 42 to the lower edge of the regulator It, and thus forms one side of a bypass through which some of the furnace gases may be directed around the superheater when superheat would otherwise be undesirably high. The regulator to is pivoted at its lower edge so that it may be moved to the dotted-line position 44 topermit all of the'furnace gases to bypass the superheatergto the around the lower edge of the baiiie It by reason of the superheater bypass baiile I04 which can-- one of the rows of tubes I08 and H0.

tends from the lower edge of the baiile ll to the lower edge of the baflle I06. The latter extends along and is supported by the tubes of at Tlfiast ese tubes directly connect the drums 62 and and extend across the path of the furnace gases as they pass from the third gas pass I20, past the dotted-line position 6 to provide for the flow of all of the furnace gases over the superheater, or to any intermediate position which may be determined automatically by temperature or pressure responsive devices, some of which may position the regulator with reference to steam flow.

The baiile 50 is shown as extending along the tubes 62 of the rear bank 2| so as to form a rear wall of the superheater bypass. This bame also extends upwardly past the regulator 36 so as to form one wall of the third gas pass 64. v The furnace gases in this gas pass pass around the upper edge of the baiile'60 and downwardly over the tubes of the bank 2I in a fourth gas pass which is defined by the baflle 50 and the rear wall 66 of the boiler setting.

The superheater, being .a convection superheater. has the inherent characteristic that the final steam temperature has a rising temperature when boiler rating increases. In the present\,installation this inherent characteristic is overcome by bypassing some of the furnace gases. When the boiler load increases and the tendency of the superheat is tobecome too high, the regulator 30 at the outlet of the superheater bypass is moved so as to permit a sufficient share of the gases to pass directly through the bypass to prevent an undesirable rise in superheat. When the boiler load is low, the regulator may be positioned as indicated at 46 in order that a greater proportion of the furnace gases shall pass over the superheater 22.

The installation indicated in Fig. 2 of the drawings includes a similar arrangement of upper steam and water drums 60, 62, and 6t connected by banks of spaced tubes to a submerged drum 66. The tubes of the front bank 68 extend over the fumace "and directly connect the drums 64 and 66, while most of the tubes of the second bank 12 are disposed in a second gas pass between the baille II on one side, and the bailles It and 10', on the other side. These tubes directly connect the drums 62 and 66.

All except the forward rows of tubes 66 and 02 of the rear bank 84 directly conneet'the rearmost steam and water drum 60 with the submerged drum 66. The tubes of rows 60 and 02 directly connect the drums 62 and 66 with the tubes 82 supporting the baiiie 00 which extends downwardly from the regulator 92 to the submerged drum 06.

In the Fig. 2 embodiment the furnace gases pass over the tubes of the bank 60 and then over the tubes of the superheater I00. From 'the 'superheater. the gases pass around the upper end of the bafiie I4 and downwardly through a second gas pass I02 between the baiiies I6 and 16.. The gases then are caused to tum upwardly regulator 92 and around the upper end of the baiile '60. The gases then pass downwardly in the-fourth gas pass I and over the tubes of the bank 64 in that gas pass. A flue I32 receiving the gases from the gas pass I30 may be arranged adjacent the submerged drum 66 as shown in the drawings.

The regulator 02 of the Fig. 2 embodiment may be automatically controlled in the same manner as the regulator 36 of the Fig. 1 modification and may be moved toward the dotted-line position I40 when boiler load is low, and toward the dotted-line position 42 when the boiler load is high, the regulator being moved to any intermediate position as determined by operating conditions,

In each one of the above described embodiments of the invention the boiler setting includes the furnace wall I extending alongside furnace wall tubes I52 from a position at the bottom of the installation to the corresponding upper drum [2 or 64. The opposite furnace wall I54 extends along the furnace wall tubes I66 to the submerged drum and the side walls of the furnaces may. be defined by similar wall tubes connected into the boiler circulation through the intermediacy of an upper header I from which steam and water pass through the risers I62 to one of the upper drums. All ofthe furnace water walls are otherwise appropriately connected into the boiler circulation.

The boiler setting in each embodiment of the invention includes a roof I10 supported by steam circulators. In the Fig. l embodiment the circulators I12 directly connect the drums I2 and I4, whereas the rear steamcirculators I14 directly connect the drums I4 and I6. Similar circulators I16 in the Fig. 2 embodiment directly connect the drums 62 and 66, whfle other circulators I'll directly connect the drums 60 and 62. In each embodiment the rear wall of the setting is indicated at I00.

In each embodiment of the invention there are a plurality of banks of upright tubes associated with a furnace and a superheater in such a way that the furnace gases are free to flow from the furnace toward the superheater and the steam generating tubes at a position near the upper part of the setting. This combination of elements is associated with a superheater bypass in which a part of the furnace gases may flow across parts of the tubes of the upright banks which are adjacent the submerged water chamber. Thus, there is an elongated gas flow path for the purpose of promoting heat absorptionby cooling merged drum, and the outlet of the bypass is adjacent the regulator.

Another advantage of the invention arises from the passage of the bypassing gases over the lower parts of the water tubes rather than their upper parts. This advantage resides in the elimination of tendencies for the hot gases to overheat the upper parts of the tubes in which there is a maximum of steam. Such local intense heating by the hot gases in the event of bypassing gases at' a lower drum, spaced banks of tubes connecting the tops of the steam generating tubes might cause these portions of the tubes to become dry and be thereby damaged.

In either of the embodiments shown the damp er constitutes a single means simultaneously controlling gas flow through the bypass and controlting the main gas flow, restricting one flow while permitting a corresponding increase in the other flow.

The damper 38 is formed by a plurality of sections as indicated in Fig. 4 of the drawings. It might be said that the illustrative arrangement of elements includes a plurality of small dampers. This arrangement advantageously prevents cumulative expansion or contraction stresses which would otherwise exist. As shown in Fig. 3 of the drawings, each damper section 38 is pivotally connected to a link 200 which passes through a housing 202 extending across the fourth gas pass and betweenv the tubes 2| in that pass. This housing also extends through the wall I80 which, at positions adjacent the housing, are provided with elements which form guideways 204 and 206 for a sliding plate 205. This plate is provided with an opening through which the link. 200 passes.

Each link 200 has its end opposite the damper section 38 pivoted to a crank-arm 2H! fixed to a shaft 2|2. Movement of this shaft is effected by the crank-arm 2M which has one end fixed to the shaft-2i! and its opposite end pivotally connected to a link 216 which, in turn, is connected to a pneumatic control device 220 by the lever 2l8. Fluid iiow to or from the dvice 220 may be controlled by devices which are responsive to steam temperature or steam flow in order that the superheat may be automatically controlled.

What is claimed is:

1. In a water tube steam boiler, upper drums, a lower drum, spaced banks of tubes connecting the lower drum to the upper drums, a furnace, a superheater, baiiles forming two separate gas paths for the travel of the furnace gases in parallel from a position forwardly of the superheater to a position beyond the first bank of tubes. one or said gas paths constituting a superheater bypass leading from the gas space beneath the superheater and across said banks of tubes at a position adjacent the lower drum, and a gas flow regulator located rearwardly oi the superheater and selectively movable to a flow restricting position for the outlet of said bypass or to a flow restricting position for the outlet 01' the other gas path to control the amount oi! bypassing gases, the superheater bypass confining the bypassing gases to contact the lower parts of the tubes of said banks adjacent the lower drum.

2. In ad-drum bent tube boiler, upper drums,

a. superheater, means connecting the inlet of the superheater to one of said upper drums, baflles providing for the movement of furnace gases over said tubes ina plurality of gas passes, said baffle means including a baflie disposed transversely of one oi. said banks and spaced vertically from the lower drum so as to provide a bypass through which some of the furnace gases may pass across the lower ends of some of the tubes and to an outlet flue while bypassing the superheater, said transversely disposed baflie extending laterally of and past the superheater and a single regulator disposed rearwardly of and across the bypass and the superheater for simultaneous. ly increasing the proportion of the total gas flow which bypasses 'the superheater and decreasing the proportion of the total gas flow which flows over the superheater.

3. In a water tube steam boiler, upper and lower drums, a furnace, spaced banks of upright steam generating tubes extending across the path of the furnace gases with each bank connecting an upper drum to a lower drum, a superheater, baiiie means so associated with said banks of tubes as to form two gas passes leading from the furnace to a common outlet position rearwardly or two of said banks of tubes, the superheater being disposed in one of said passes and the other of said passes constituting a superheater bypass, a gas flow regulator damper poupwardly extending banks of water tubes connecting said drums, a furnace, 'a superheater positioned between a front tube bank and a second tube bank and contacted by furnace gases passing from the furnace over said front tube bank, upwardly extending front and rear baifies associated with the second bank to define a downflow gas pass connected to the superheater space at its upper end, said downflow pass extending for a portion only of the height 01' said second bank, means forming an upflow gas pass disposed between the rear tubes of said second bank and a row of rearwardly spaced tubes connecting the lower drum and an upper drum, said upflow pass communicating with the outlet 01' said downfiow pass, means forming a gas flow passage across the lower portion of said second tube bank communicating with the lower end of said upfiow pass, and a damper extending transversely of the boiler and transversely of gas flow beyond the superheater and pivotally supported on tubes marginal to said upflow pass to control the gas fiow over said superheater and through said downfiow pass.

- IVAR L. LANGVAND.

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