US2075059A - Boiler drum equipment - Google Patents

Description

March 30, 1937. F. H. ROSENCRANTS ET AL 2,075,059

BOILER DRUM EQUIPMENT Filed May 7, 1934 2 Sheets-Sheet 1 ATTORNEYS F. l- RosENcRANTs ET AL 2, 75,059

March 30, 1937.

BOILER DRUM EQUIPMENT Filed May 7, 1934 2 Sheets-Sheet 2 INV NTORS Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE BOILER DRUM EQUIPMENT ware Application May '1, 1934, Serial No. 724,240

16 Claims.

This invention relates to boiler drum equipment and is especially concerned with the provision of novel steam washing, purifying and separating apparatus, and with novel feed water 5 admission means.

Among the more important objects of the invention are: the provision of equipment tending to produce a substantially unbroken sheet of water in the path of flow of steam, especially in 10 a steam and water drum, from the steam inlet to the steam outlet thereof; the employment of very simple and yet effective means, such as perforated sheets or screens, for the purpose of aiding in the formation of the water sheet and aiding 15 in maintaining this sheet substantially unbroken,

so that the steam in passing therethrough is thoroughly scrubbed or washed; the provision of means for avoiding water hammer in the introduction of boiler feed water; and the provision of 20 a novel means for delivering the feed water introduced to the perforated members already mentioned so as to produce the water sheet through which the steam is caused to pass.

Other advantages attained by the structure 25 hereinafter to be described include effective dry scrubbing of steam after passage thereof through the water sheet; and the arrangement of the various devices and elements of our invention in a manner to afford adequate capacity so as to take care of maximum operating loads and so as to fit within a boiler drum of substantially normal size and yet be readily accessible for purposes of inspection, cleaning, and the like.

Still further the invention has in view reduc- 35 ing the accumulation of deposits on screen or separating elements of the general typehere involved, and thus at least materially reduce clogging of such elements.

We also contemplate boiler operation somewhat 40 difierent than has been customary heretofore,

especially when employing the equipment to be described, in which event practically complete freedom from clogging of strainer elements is attained, and other desirable advantages secured,

45 all as will more fully appear hereinafter.

50 ing drawings, in which Figure 1 is a transverse sectional view through a drum incorporating equipment of the present invention;

Figure 2 is a similar view illustrating a modi 55 fied form of the equipment; and

Figure 3 is a somewhat diagraminaticview of vertically spaced drums of aboiler installation, the upper one of which incorporates screening means and the lower one of which is provided with a means for admitting phosphate, in accordance with this invention.

Referring first to Figure 1, the drum, indicated by the numeral 3, may be that of substantially any known type of boiler, although in this instance it will be seen that the drum is of the steam and Water type from which a number of downcomers 4 extend from a lower part thereof. Steam produced in the boiler (usually containing considerable quantities of water) is introduced into the particular drum shown by means of tubes 5. A steam outlet appears at 6 toward the top of the drum. The water level in the drum appears at W.

A feed water inlet pipe is shown at 1 as being submerged below the surface F of feed water in a trough 8 which is supported in an upper region of the drum by a partition or sealing plate 9 which has means of attachment to the inside drum wall. The trough 8 preferably extends for a substantial distance lengthwise of the drum, as does also the sealing plate 9, and the inlet pipe I is preferably equipped with a plurality of discharge openings lO spaced along the pipe 1 and positioned below the surface F of the water in the trough. At this point it is to be noted that an important feature of the feed water inlet lies in the fact that the discharge openings are disposed below the surface of the water in the feed water trough. This prevents steam from entering the feed water line and thus eliminates water hammer. Pipe arrangements other than that just described, so long as the discharge openings are submerged in the manner mentioned, will answer this purpose.

Depending from a point preferably just below the trough 8 are a number of apertured elements such as screens H to l inclusive. The first of these screens (ll) preferably has its upper edge located adjacent to one lower edge (the left hand in Figure 2) of the trough 8. As shown in the drawings, the screens are preferably located in slightly spaced parallel planes, transverse belts or the like I6 carrying spacing washers I! being provided for this purpose. For convenience in mounting, the screens II to [5 inclusive may be divided into two groups. In the showing of Figure 1 the first group includes four screens (11 to 14 inclusive) and the second group four additional screens IS. The devices l6 and I! may be duplicated for the second set. The several screens may conveniently be supported, by their upper edges, in association with the feed water trough 8 and, as clearly shown, the screens project below the normal water level W to receive 5 support adjacent their lower edges as by means of one or more strips I8 which may be attached to the drum wall as at 19 and 20, the latter point of attachment being at a point toward the bottom of the drum from which a supporting strap 2| 10 extends upwardly. Tubes or equivalent elongated members 22 afiixed to the straps i8 serve to position the lower edges of the screens.

It is here pointed out that the angularity or inclination of the screens referred to above, es-

pecially screens II and I2, is of importance in the operation of our improved equipment, this matter being touched on more fully in the discussion of the operation appearing hereinafter. .At thls time, however, it should be observed that the screens are interposed in the path of flow of steam from the tubes 5 to the outlet 6. Preferably, the screens are extended along the length of the drum for a distance equal to or substantially equal to the length of the bank of tubes 5 which enter the drum. In order to ensure fiow of substantially all the steam through the screens, baflle plates 23 lying in vertical planes cross-sectionally of the drum are employed there being one positioned adjacent each end of the screens. These plates may be attached to the drum wall as by means of the angles 24. The bailies 23, furthermore, preferably fit the inside of the drum from a point above the feed water trough 8 adjacent the partition or sealing plate 9,

downwardly to a point well below the level of water in the drum, a lower edge being indicated at 25. The lower edge of each of plates 23 may conveniently be attached as by means of the bolts a- 26 to a flange 21 depending from strap 18. Longitudinally extending flange or baffle elements 28,

below straps l8, may be employed to aid in preventing short-circuiting of steam from the inlet to the outlet side of the screens below the water level in the drum.

As indicated by the arrows, the feed water in trough 8, preferably overflows at the left side thereof, a multiplicity of fairly closely spaced small weirs or notches 29 being provided to ensure substantially uniform overflow from end to end of the trough. The overflowing water is directed downwardly and thence inwardly by the guide plate 30 which may be attached at spaced intervals to the trough wall as at 31 and also to the drum wall as at 32. This lends additional 5 support to the trough. The lower edge of guide plate 30 is bent inwardly as shown at 33, in order to direct the water onto the first and second screens II and 12. An additional guide plate 34 positioned just beyond the second screen l2 aids 60 in directing the water downwardly between and over the surfaces of the first two screens.

Toward the upper right-hand portion of Figure 1 an additional group of screens 35 is preferably positioned, this group being extended angu- 5 larly from a point adjacent the trough 8 where support maybe had as by means of the angle 36 to a point adjacent the drum wall where an additional support device 31 is provided. Partition or baflie plates 38, supported by angles 39,-are

70 again positioned toward the ends of screens 35 so as to ensure flow of all steam from the central region of the drum through screens 35 in passing to the outlet 6.

Since numerous operating characteristics of 75 both forms of he invention il ustrated in the drawings are the same or similar, reference is made to the structural features of Figure 2 before discussing the operation.

The drum 4!! of Figure 2 is also of the steam and water type, although the tube connections 5 are of a different arrangement. Downcomers 4| appear toward the bottom, but two groups or banks of inlet tubes 42 and 43 are here shown, one located toward one side of ,the drum and the other toward the other side. A pair of outlets 1o 44 and 45 are also shown spaced alittle from each other adjacent the top. While the feed water inlet connection may be extended into the drum at any convenient point, in Figure 2 it is shown as entering through the top wall as at 46, from 15 which it extends downwardly to connect with horizontally extending branches 41 and 48. In this instance a pair of feed water troughs are employed, each of which is essentially similar to the one described in connection with Figure 1. 20 Note, by way of example, that each includes a pipe 1 submerged therein, which pipes, of course, are fed from the branches 41 and 48.

The screens 49 toward the left of Figure 2 are arranged at an inclination similar to that of Fig- 25 ure 1, although in this instance the entire set of screens is mounted in one group as by means of bolts or spacing collars l8 and IT. Positioning members 22 carried by one or more transverse straps 18a serve to support the lower ends of the 30 screens 49 below the water level W. In the showing of Figure 2 the straps 18a extend all the way across the lower part of the drum so as to support the lower ends of additional screens 50 and 5i which are divided into two groups some- 35 what after the manner of Figure 1. End plates 23 and 23a similar to those described above, are positioned at the ends of the several sets of screens with a view to ensuring flow of all incoming steam through the screens when passing to 40 the outlets.

As to the group of screens 50, it will be observed that the feed water in overflowing from the righthand trough is guided by means of plate 52 downwardly and inwardly against and through 45 the first screen. A cooperating guide 53 directs the flow between and over the first two screens. Complementary devices 54 and 55 are associated with the first two screens 49 at the left side of the drum. An additional baffle plate 56 also 00- 50 operateswith the guide plate 54. The member 56 is preferably co-extensive in length with member 54 and may be parallel thereto so as to provide a small surge chamber 51, tending to smooth out small variations of water flow from the 55 trough. This feature, of course, may be incorporated in the feed water delivery devices elsewhere shown in the drawings.

In the arrangement of Figure 2, additional screens are shown toward the topof the view, these being positioned and divided into groups in such a way as to increase the steam flow capacity, without, however, necessitating enlargement of the drum. More specifically, these screens are divided into two groups 58 and 59, which two groups are arranged to form an inverted V, the apex of which is located adjacent the top of the drum at a point intermediate the two outlets 44 and 45. The lower edge of group 58 may be supported as by means of the bracket or shelf 60 and the lower edge of group 59 on a similar shelf 8|. Partition plates 82 and 63 are arranged at the ends of these two groups so as to ensure steam flow from the central region of I the drum through the screens in passing to the outlets.

As to Figure 2, it is noted that a greater number of inlet tubes enter at the left side than at the right side, and that the screen and steam outlet devices are arranged in a novel manner in accordance with which the right-hand group of screens 59 at the top are of large capacity and extend a considerable distance downwardly since,

at this side, where a smaller amount of steam is introduced, the screens 5| need not be of such large size. On the other hand, at the left of the drum, where a larger quantity of steam is introduced, the screens 49 are of relatively large size and we therefore employ somewhat smaller screens 58 thereabove. The inverted V-formation of screens at the top is, itself, a factor in providing relatively large screening area so as to avoid material resistance to flow. Accordingly,

relatively. large quantities of steam may be handled by means of equipment of minimum over-all dimensions.

At this time it is pointed out that an important consideration in boiler operation (especially where purifying, separating or screening devices are employed in a drum) arises by virtue of solids which are carried in suspension or solution in the steam or in the moisture carried by the steam. A high concentration of solids is undesirable for a number of reasons, particularly because of the tendency to produce foaming with its concomitant difiiculti'es. Furthermore, other difiiculties, especially clogging of screens or equivalent devices, have been encountered heretofore where the steam is mingled with pretreated feed water just prior to passing through the screens or equivalent separating devices. It has been customary heretofore to give the feed water, prior to admission into a boiler, a phosphate treatment. The prosphate reacts with calcium compounds present in the water to produce calcium phosphate, which is more soluble in cold water than in hot water. With the above in mind, it will be seen that mixture of such pretreated feed water 45 with steam at very high temperature, has a tendency (because of lower solubility at high temperatures) to produce deposits in the screening or other equivalent equipment.

According to this invention, phosphate is preferably admitted to the boiler at some point remote from the steam purifying and separating equipment in the drum, and the feed water which forms the water sheet in the path of the steam entering the drum is free of phosphate. The admission of phosphate may be accomplished as illustrated in Figure 3 which shows an upper drum 64, and lower drum 65 with tubes 66 therebetween. The upper drum is equipped with screening elements shown at 61 to which water is delivered from the feed water admission means 68. The phosphate may be introduced into the lower drum 65 by means of the pump shown at 69.

The result of this arrangement is that the solids content in the water carried by the steam is materially reduced by mixture thereof with the pure feed water and, in consequence, the deposits which heretofore have caused the difiiculty referred to are very substantially reduced, if not eliminated. An important feature of the equipment of this invention, therefore, is the reduction of the solids content of the steam almost immediately upon entrance of the steam into the drum, this deconcentration being effected by virtue of the passage of the steam through the sheet of water provided on and between the first two screens I and I2 in the arrangement of Figure 1, and .in the corresponding screens in the arrangement of Figure 2. The fact that the feed water is free of phosphate and relatively pure, prevents deposits of compounds on these first screens and during the flow of steam through the remaining screens there is no appreciable tendency for clogging to take place because of the very low solids concentration.

Turning now to the angularity of the several screening elements employed in the settings of Figures 1 and 2, especially the inclination of the first two screens, it is mentioned that while this inclination is not a matter of very fine adjustment, it should be noticeably off the vertical and may be as much as or even a little farther from the ver ical. I have found the angularity of the screens l and I2 of Figure 1 to be efi'ective for most purposes. the action of gravity on the water on the screens aids in keeping the water sheet intact, and we might further state that the angularity should be sufiiciently off the vertical so that the combined action of gravity and of surface tension will produce a substantially unbroken sheet of water flowing downwardly between and over the first two screens even with relatively high ve locity steam flow. Furthermore, we have found that the proper angularity will produce the desired results even if the customary bafiles im- 'mediately in front of the delivery ends of the tubes entering the drum are eliminated. It has also been found that sprays and other devices employed previously in attempts to secure a substantially continuous water sheet, were frequently broken through by the steam flow, especially at high rates of operation, with consequent ineffective and incomplete washing and deconcentration.

The direction of inclination is preferably as indicated in the drawings, i. e., toward the side from which the steam approaches and passes through the screens. The screens I3, I 4 and I 5, in Figure 1, of course, are eifective to remove moisture as are also the dry scrubber screens 35.

By virtue of the angularity,

Similarly, in Figure 2, the first two screens 49 at the first two screens 50 provide the water sheet and the third screen 50, as well as the three screens 5 i, remove moisture. In addition, the upper screens 58 and 59 serve a similar purpose.

An additional advantage which is mentioned at this time resides'in the fact that, when inclined noticeably from the vertical as shown, for example, at the left of Figure l, the first one or two screens serve to provide a sheet of water through which the steam first passes, which sheet will be maintained under quite widely varying operating conditions, including velocity of steam flow.

As hereinbefore mentioned, the feed water admission pipes, in the arrangements shown, are

inlet and a steam outlet, a screen positioned in the path of steam flow from the inlet to the outlet, said screen being inclined from the vertical toward the inlet side, means cooperating with the screen for causing substantially all of the steam entering the drum' through the inlet to flow through the screen, and a boiler feed water inlet from the vertical in a direction toward the inlet side of the screen, and means for feeding water ,to the screen in an upper portion thereof to flow downwardly over the screen surface.

3. A steam washer for a steam chamber of a boiler having an inlet and an outlet, the washer including a screen interposed in the path of flow of steam from the inlet to the outlet and inclined from the vertical in a direction toward the inlet side of the screen,-means for feeding water to the screen in an upper portion thereof to flow downwardly over the screen surface, and a steam scrubber screen interposed in the path of steam flow between the screen and the outlet.

4. A steam washer for a steam chamber of a boiler having an inlet and an outlet, the washer including a screen interposed in the path of flow of steam from the inlet to the outlet and inclined from the vertical in a direction toward the inlet side of the screen, and means for feeding water to the screen in an upper portion thereof to flow downwardly over the screen surface, the inclination of the screen being sufficient to provide for flow of the water downwardly on the screen in the form of a substantially continuous sheet.

5. In a steam and water drum having a steam inlet and a steam outlet, a screen positioned in the path of steam flow from the inlet to the outlet, said screen being inclined from the vertical toward the inlet side and having its lower edge projecting below the water level in the drum, and a boiler feed water inlet extended into the drum and delivering feed water to the screen in an upper portion thereof to flow downwardly over the screen to the surface of the water in the drum.

6. In a boiler drum having a steam inlet and a steam outlet, a generally upright screen interposed in the path of flow of steam from the inlet to the outlet, a trough positioned in an upper part of the drum, conduit means for delivering feed water to said trough projecting below the surface of the water in the trough and having a feed water discharge opening below said sur.-

face, means providing for overflow of water from the trough along an extended length thereof, and guide means directing the water overflow onto said screen.

'7. In a boiler drum having a. steam inlet and a steam outlet, a pair of screens arranged in close and parallel relation and positioned in the path of flow of steam from the inlet to the outlet, the screens being generally upright, and means for delivering water to said screens including a water inlet adapted to deliver water along the upper edge of the screens, guide plates disposed one at each side of the upper edge of the screens to direct the water over the surfaces of and between said screens in a direction generally parallelingthe planes of the screens.

8. In a boiler drum having a steam inlet and a steam outlet, a feed water inlet trough extended generally axially of the drum in an upper portion thereof and having a feed water overflow along a side, a pair of screens depending from the trough and interposed in the path of flow of steam from the inlet to the outlet, and a guide plate for the water overflow for directing the same laterally into said screens to flow downwardly over the surfaces thereof, and an additional guide positioned at the opposite side of said screens and having a portion generally paralleling the screens to aid in directing the water in a path paralleling the screens.

10. In a boiler drum having steam inlets toward opposite sides thereof and a steam outlet in an upper region between said inlets, a screen interposed in the path of flow of steam from one of said inlets to the outlet, a second screen interposed in the path of flow of the steam from the other of said inlets to the outlet, means for flowing water over said screens, a third screen positioned in advance of said outlet in the path of flow of steam from the first and second screens to the outlet, and baille or wall plates cooperating with the edges of the screens and with the drum wall to prevent short-circuiting of steam around the screens and ensure flow therethrough.

11. In a boiler drum having a steam inlet toward one side thereof and a steam outlet adjacent the top of the drum, boiler feed water admission means positioned in the drum in an upper region thereof generally between the inlet and the outlet, means restricting flow of steam from the inlet to the outlet over the top of the feed water admission means, a generally upright screen depending from said admission means and to which the feed water is delivered to flow downwardly over the surfaces thereof, and a steam scrubber positioned in the path of flow of steam from said screen to the outlet and extended from a point adjacent the feed water admission means toward the side of the drum opposite the steam inlet.

12. In a boiler drum having steam inlets toward opposite sides thereof and a steam outlet in an upper region between said inlets, a screen interposed in the path of flow of steam from one of said inlets to the outlet, a second screen interposed in the path of flow of the steam from the other of said inlets to the outlet, a boiler feed water inlet adjacent the upper edge of the first screen and adapted to deliver water to the surfaces thereof, and a second boiler feed water inlet adjacent the upper edge of the second screen and adapted to deliver water to the surfaces thereof, the said screens each being inclined somewhat with respect to the vertical in a direction toward the side from which the steam enters each screen.

13. A drum structure having steam inlets toward opposite sides thereof and a pair of outlets circumferentially spaced from each other in the path of steam flow from the inlet at the other side of the drum to said outlets, partition or baflie plates cooperating with the screens and the drum wall to direct flow oi substantially all the steam admitted through said-screens ,to a central region of the drum, and additional screen means extended across said central region from the upper edge of the first screen to the upper edge of the second screen and interposed in the pathof flow of steam from said central region to said outlets.

14. A drum structure having steam inlets toward opposite sides thereof and a pair of outlets circumferentially spaced from each other toward-the top thereof, a generally upright screen interposed in the path of flow of the steam from the inlet at one side of the drum to the outlets, a second generally upright screen interposed in the path or steam flow from the inlet at the other side of the drum to said outlets, partition or batfle plates cooperating with the screens and the drum wall to direct flow of substantially all the steam admitted through said screens to a central region of the drum, and additional screen means above said central region and interposed in the path of flow of steam therefrom to said outlets, there being a screen interposed between said region and one of said outlets and another screen interposed between said region and the other of said outlets.

15. Steam washing equipment including a generally upright screen, means for delivering water to the screen in an-upper portion thereof to flow downwardly over the surfaces of the screen, and a surge chamber associated with said means adjacent to the point of feed of water to the screens, whereby to enhance regularity and evenness of flow of the water.

16. In a boiler drum having a steam inlet and a steam outlet, a generally upright screen interposed in the path of flow of steam from the inlet to the outlet, a trough positioned adjacent the upperedge of the screen, means for delivering feed water to said trough, means providing for overflow of water from the trough along an extended length thereof, and guide means directing the water'overflow onto said screen.

FAY HARRY ROSENCRANTS. ALBERT CHARLES WEIGEL.

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