US2024324A - Fluid heat exchange apparatus - Google Patents

Description

Dec. 17, 1935. P. R. YOPP FLUID HEAT EXCHANGE APPARATUS Filed May 4, 1933 2 Sheets-Sheet l o o o o o o o o a o 00 0o 00 0o INVENTOR Paul I? yo Jp A ORNEY OOOOOOOOO 000000000 0 0o 0o 00 0o 0 0o 00 0;)

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Dec. 17, 1935. p. R. YOPP 2,024,324

FLUID HEAT EXCHANGE APPARATUS Filed May 4, 1935 2 Sheets-Sheet 2 O O0 00 OO O0 COO 0000 OO O GO Q0 00 OO o o o o o o o o o 000 000009 OOOOOOOOO o o o o o o o o o 5's G2 ATTORNEY Patented Dec. 17, 1935 UNITED STATES FLUID HEAT EXCHANGE APPABATU Paul R. Yopp, Atlanta, Ga., assignor to The Babcock & Wilcox Company, Newark, N. 1., a cor- 4 poration of New Jersey Application May 4, 1933, Serial No.669399 8 Claims. (01. 122-402) This invention relates to water tube steam boilers.

It .is an object of the invention to provide a uniform and eflicient distribution of gas flow through a bank of boiler tubes for maintaining the effectiveness of the heat transfer surfaces.

It has been proposed to distribute gas flow through banks of boiler tubes by the use of spaced bafile elements secured to the tubes and complete- 1y closing the gas space between tubes where located, but such proposals have been found to have certain undesirable features which it is an object of the invention to eliminate.

It is also an object of the invention to reduce draft losses in steam boilers by eliminating reversals of the whole stream of heating gases in bulk, flowing over the water tubes which is typical of baflied constructions. It is also an object of the invention to accomplish good distribution of gas from end to end of all tubes and side to side across the bank without the provision of costly baiiie constructions and with the least draft loss consistent with such gas distribution.

A more specific object of the invention is to provide a single pass water tube steam boiler in which the tubes themselves are arranged so as to accomplish proper gas distribution within banks of boiler tubes.

Other objects will appear as the accompanying description proceeds.

The invention will be described with reference to the embodiments shown in the accompanying drawings, in which:

Fig. 1 is a vertical section through aboiler constructed in accordance with the teachings of this invention.

Fig. 2 is a transverse section through the tube I I bank section taken on the line 2-2 of Fig. 1.

Fig. 3 isa transverse section through a boiler illustrating another embodiment of the invention. Fig. 4 is a transverse section on the line 4-4 of Fig. 3. Y

Fig. 5 is a view in the nature of an elevatio looking in the direction of the arrows 5-5 in Fig. 4. The single pass boiler shown in Fig. 1 includes a bank of tubes Ill positioned between a front bank l2 and a rear tube bank l4. These banks of tubes connect upper drums l6; l8 and 20 with a lower drum 22. They extend transversely of a gas pass extending from the furnace 24 toaflue connection 26 which is the outlet for furnace gases. In the operation of the boiler, the gases are not deflected in bulk in their flow. They flow in a single pass and'in a direction substantially normal to the directions at which the tube banks extend. I

. The lower part of Fig. 2 indicates the arrangement of tubes in the front bank l2. As shown. a1-

ternate tubes 2| in the front row are bent at their ends so that-their main portions are p i tioned between two adjacent tubes of pairs of tubes III in the second row. when the remaining tubes 32 in the front row are not so bent, the tubes in the second row are thus fo'rmedinto groups of three I with the spacing between the three tubes of each group much less than it is between the successive groups. I Immediately rearwardly of the openings 34' between the groups of tubes in the second row 34, 1 v

are other groups of closely spaced tubes. The latter groups are so situated as to cause the fur' nace gases passing through each of the-main openings between the groups of the second row. to be divided'and to be distributed over the re- 15 maining tubes of the bank. At the same time some of the gases may flow between adjacent tubes of each group. 'As shown the latter groups of tubes are formed by bending alternatetubes 38 of the rear row of tubes in the front bank 29 so that their main portions lie closely adjacent and parallel to tubes 40 of the row thus restricting but not preventing gas flow between tubes of each group and leaving an unobstructed path between groups. v v 25 As a result of the displacement or bending of tubes 28 in the front row of the tube bank II, the remaining tubes 12 in the front row of tubes in that bank form a widely spaced tube screen adjacent the furnace. This screen absorbs heat from the gases and radiantly. fromthe furnace without-materially reducing heat absorption of the other tubes, and particularly the radiant heat absorption of the tubes in the first row of groups transversely of the boiler behind the screen. 35

It is not necessary that the gas distributors formed by the'groups of closely spaced tubes be located in a shallow bank of tubes as shown. They may well be arranged in eitherthe front; rear or central portion of a shallow or deep bank o'ftubes. Y a

After passing the tubes in the front bank 12 the gases pass through the superheater space A between banks in which may be located a super-v heater l9. i

The tubes of the second bank III are preferably arranged for gas distribution as indicated in the 1 middle part of Fig. 2 of the drawings. As here shown, the first four rows extending transversely of the gas pass have the usual spacing in which 0 g each tube in one of those rows is located at unequal distances from adjoining tubesin the same row, to permit of tube removal between alternate rows. For example, the tube 42 is closer to the tube 44 than is the next successive tube. 48 in'the same transverse row. This normal spacing:is usually such .as to leave to large a gas areafor' equal gas distribution. I I

Towards the rear. of the middle bank ll all of the tubes 48 of the rear row are preferably bent so that they are positioned between and more or less closely adjacent to the tubes 80 of the next forward row. This arrangement of elements produces a gas flow restricting wall preferably extending entirely across the gas pass. By this restriction of gas fiow area between tubes distribution of the gas over all of the tubes from end to end and side to side is promoted.

The gas flow distributors formed by the closely spaced tubes in the second bank need not necessarily be located at the rear of that bank. They may be positioned centrally of the bank or still further forwardly. The particular arrangement of gas distributors shown is preferable where a superheater is employed in combination with the banks of boiler tubes.

Although the rear tubes of the bank I! are closely spaced for the purpose of gas fiow distribution they are not so closely spaced as to prevent fiow between them or to become clogged with dust or solids deposited from the hot gases. There is sufiicient fiow of gas between these tubes to remove any particles of dust or similar solids which may tend to deposit on those tubes and the gas may flow around the whole tube circumference. This spacing of the rear tubes may be varied in accordance withthe characteristics of different fuels and also in accordance with diameters of the tubes which are used in the construction of the boiler with due regard for the quantity ofgases discharged from the furnace. larger quantities requiring less restriction of flow area in the tube bank than smaller quantities, to give proper distribution with a minimum The tubes of the rear bank ll are shown in Fig. 2 as having an arrangement similar to that of the tubes in the middle bank ll with the tubes of the last two rows 52 and 54 being in close] spaced relationship as shown.

The boiler indicated in Fig. 3 of the drawings has the tubes of its middle and rear banks 58 and 58 arranged in substantially the same manner as that in which the tubes of the banks I and ll of the boiler of Fig. 1 are arranged. The tubes of the front bank 80 are provided with gas distributionfiow restricting elements which are preferably tiles 62 held in place by their engagement with the tubes of the row in which they are located,- as shown here the second and last rows 64 and 66 respectively. These tile are preferably shaped as c-tile with their curved portions fitting closely against the tubes. As shown they form a closure for the alternate spaces between successive tubes in each of the rows" and 68. They are so constructed that they may be put into position without additional securing means, and after the tubes and the drums of the boiler are in their operative positions, and are replaceable at any time.

As indicated in the lower part of Fig. 4 of the drawings the c-tile 62 form spaced fiow obstructions constituting a general restriction in the row 64 alternating with unobstructed openings between tubes which are staggered with respect to the position of the obstructions and openings in the row 88. This arrangement causes the gases passing between tubes in the row 64 to be divided and to pass between tubes in different longitudinal rows in the row 68.

When c-tile are used to distribute gas flow in the forward bank of tubes as indicated in Figs. 3, 4, and 5, the tubes of a superheater may be easily removed by passing them betwe n the tubes of the front bank.

Fig. 5 indicates three superposed pairs of the c-tile 82 between adjacent tubes. The tiles of the fourth pair in each intertube obstruction are indicated at Cl as being slightly wider than the other tile. They thus extend further sidewise 5 over the contacted tubes and act as supports for spacer tile II in the otherwise unobstructed spaces between tubes. These spacer tile may be somewhat of the form of c-tile, but they are wide enough transversely of the tube bank to act as tube spacers to maintain the tubes in their desired relationship. In other words, the spacers maintain the tubes and the fiow spaces between them in uniform relation.

As indicated in Fig. 3 of the drawings, there are three rows of spacer tile or blocks Ill transversely of the tube row 84. The same figure shows four rows of spacers across the tube row 60.

The end obstruction tile 81 shown at the position B in Fig. 3 may be provided for controlling the amount of gas passing between the main body of the closely spaced tubes where they are parallel as compared to the amount of gas which is passing near the ends where the tubes are bent and not parallel and otherwise of unrestricted fiow areas. These end obstruction tile will limit the amounts of gases by-passing the gas fiow distributors formed by the closely spaced tubes. The extent to which the intertube spaces at B are closed with baille tile will depend upon gas conditions and the loads or ratings at which it is d sired to operate the boiler.

In all of the modifications shown in the drawings the boilers are regarded as being free of gas boundary baiiles situated in the tube banks. The closures M and it merely act to prevent the movement of gases into the spaces between the drums ii, i! and 20. In these single pass boilers the areas of the tubes to be contacted by the gases are so extensive that there would be a 40 marked inequality in the gas flow over the various tubes if gas distributors were not provided. The arrangement of closely spaced tubes described may be considered as embodying gas flow restriction gas distributors in the various banks. As here indicated these distributors are formed in the banks themselves by elements which are parts of those banks.

While the invention has been described with reference to certain definite modifications, it is to be appreciated that it is not limited thereto, but is of a scope commensurate with the scope of the subjoined claims.

What is claimed is:

1. In a water tube steam boiler, a furnace. a furnace gas flue, and front and rear banks of water tubes extending transversely of gas fiow" from the furnace to the flue, the tubes of the front bank being bent and arranged to form groups which are positioned in a plurality of rows extending transversely of the gas fiow, the groups forming gas fiow restricting gas distributors which are positioned in staggered relationship in the successive rows, the tubes of the rearmost rows of the rear bank being bent into aoagsaa and the groups constituting the bafiing for the front bank of tubes, a rearward bank of tubes connecting the mud drum with one of the upper drums, a plurality of rows of tubes in the rear bank being bent so that they have a spacing transversely of the gas pass which is less than the spacing of the remainder of the tubes in the rear bank, the closely spaced tubes of the rear bank constituting a gas flow restrictor causing the heating gases to be distributed throughout the length of that bank, a furnace delivering heating gases forwardly of the front bank of tubes whence the gases travel transversely of the tubes of both banks to a position behind the rear bank, and a flue for heating gases behind the rear bank.

3. In a single pass water tube steam boiler, a plurality of spaced steam and water drums, a mud drum, banks of steam generating tubes each connecting the mud drum and one of. the steam and water drums, a furnace discharging heating gases forwardly of the front bank of tubes, and a heating gas flue behind the rear bank of tubes, some of the tubes of the front bank being bent so as to form with adjoining tubes spaced groups of tubes staggered in successive rows transversely of the gas pass with the gas passages between adjoining groups being greater than the passages between adjacent tubes of a group, some of the tubes of another bank in at least one of the rows having a spacing which is less than the spacing of the remainder of the tubes of that bank whereby a gas flow restrictor extends entirely across the gas pass in said bank.

4. In a single pass water tube steam boiler, a plurality of upper drums including front and rear drums, a mud drum, 2. front bank of tubes connecting the mud drum to the front drum and arranged in groups staggered in successive rows transversely of the gas pass with the heating gas openings between adjacent groups greater than the passages between the tubes of a group and the groups constituting the baiiiing for the front bank of tubes, a rearward bank of tubes connecting the mud drum with one of the upper drums and spaced from the front bank, a plurality of rearmost rows of tubes inthe rear bank being bent so that they have a spacing transversely of the gas pass which is less than the spacing of the remainder of the tubes in the rear bank, the closely spaced tubes of the rear bank causing the heating gases to be distributed throughout the length of that bank, a furnace delivering heating gases forwardly of the front bank of tubes whence the gases travel transversely of the tubes of both banks to a posirows, a furnace discharging heating gases forwardly of the front bank, and a heating gas flue rearwardly of the rear bank, the grouping of tubes in the front bank, and the close spacing of the rearmost tubes of the rear bank distributing the heating gases as they pass transversely of the tubes without well defined movements longitudinally of the tubes.

6. In fluid heat exchange apparatus, spaced fluid chambers, a single pass non-named boiler including a plurality of banks of spaced and inclined fluid heating tubes connecting the chambers and disposed transversely of a gas pass, and

means including a furnace and a flue on opposite sides of the banks providing for a flow of heating gases'transversely of the banks, said tubes being disposed in a plurality of rows across the gas pass and the tubes in the rearward two rows of a rearward bank relative to gas flow being arranged with a spacing much smaller than that of the tubes of the majority of the rows of the bank so as to form a gas flow restrictor consisting of non-contiguous tubes distributing the flow of gases over the bank, the rows of tubes in front of the flow of restrictor being greater than the number of rows of tubes constituting the restrictor.

7. In fluid heat exchange apparatus, spaced fluid chambers, a single pass non-bafiied boiler rows of the bank so as to form a gas flow restrictor consisting of non-contiguous tubes distributing the flow of gases over the bank, the rows of tubes in front of the. flow restrictor being greater than the number of rows of tubes constituting the restrictor so that'the flow restrictor and gas distributor provides a relatively small portion of the total fluid heating surface of the entire bank, all of the intertube heating fluid passages of the restrictor being smaller than the intertube passages in the major portion of said rearward bank.

8. A single pass non-baflled boiler of the Stirling type including a plurality of banks of spaced and inclined fluid heating tubes disposed transversely of a gas pass, upper and lower drums connected by said tubes, and means including a furnace and a flue on opposite sides of the banks providing for a flow of heating fluid transversely of the banks, said tubes being disposed in a plurality of rows across the heating pass and the tubes in a plurality of rows of each of a plurality of banks being arranged with a spacing much smaller than that of the tubes of the majority of the rows of the respective banks so as to form gas flow restrictors consisting of non-contiguous tubes distributing the flow of gases over the banks, the remainder of the rows of tubes in each of the respective banks being greater than the number of rows of tubes constituting the restrictor of each bank so that each flow restrictor and gas distributor provides a relatively small portion of the total fluid heating surface of the entire bank, all of the intertube heating fluid passages of the restrictor of each bank being smaller than the intertube passages in the major portion of each of said banks, said tubular restrictors operating to uniformly distribute the gases over the heat exchange surfaces of said banks of tubes so that the boiler will operate effectively without reversal of gas flow.

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