US2287592A - Steam purifying apparatus - Google Patents

Description

June 23,1942. v ANDREWS` 2,287,592'

- v STEAM PUIFYING APPARATUS 4Filed Feb. 15, 19407 ffffffffffffffffffffffffffffffff Y* l 'i lilill 28 35 3, Z5 'y L'I'l/.NDEWJ Flag. .3 5g

Pateted Junezs, 1942 UNITED' vSTAT STEAM PURIFYING APPARATUS L V Andrews, Worcester, Mass.,.assig"nor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Application February 15, 1940, Serial No. 319,083

s Claims.

This invention relates to steam purifying'apparatus, and more particularly to apparatus capable of removing substantially all foreign matter from the steam before it leaves the boiler.

The water in a steam boiler` is usually main' tained at -a rather high concentration of solids in order to reduce the amount of blow-down required. Consequently thev steam when first liberated is appreciably contaminated by solid matter, some of which is insoluble-and some of which is dissolved 'in the water carried in suspension in the steam.` -The suspended moisture can usually be evaporated in the boiler super# heater, but if the solid matter is not removed it will cause serious difficulties, particularly by forming deposits in the machine, such as turbines, to which the steam is delivered.

It has heretofore been proposed to wash -the steam by means of the feed water entering' the boiler, and while this brings about an appreciable purification of the steam it is not thoroughly effective, since the feed water itself 1is usually contaminated to some extent and may even contain appreciable quantities of solids which have been added to reduce scale formation or other difficulties in the operation of the boiler. It has also been proposed to pass the steam through pools of water, and to replenish these pools by means of condensate which is, obtained by bringing the washed steam into contact with the outside surfaces of horizontal metal tubes through which .the boiler feed water flows.

This apparatus requires an expensive drum,.

apart from the drums of the boiler, and`it re- -quires such a maze of baiiles, compartments and It is a 'further object of the invention to provide a hghlyefcientsteam purifying apparatus mounted within the steam-and-water drum of a boiler.A

. It is a further object of the invention to provide a dependable steam purifier which will remove substantially all foreign vmatter from the steam before it leaves the boiler, and which will be unaffected by variations in the Purity of boiler feed water.'

With these and other objects in View, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the `claims appended hereto.

Referring to the'drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

yFig. 1 is a section through a steam purifyingv apparatus, taken on the line l-l of Fig. 3;

Fig. 2 is an enlarged fragmentary section on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary section on the line 3-3 Y of Fig. 1; and

Fig. 4 is a'section similar to a portion of Fig. 1 but showing a slight modification.

The embodiment illustrated comprises ya horizontal cylindrical boiler drunr I0 which may form the steam-and-Water drum of a well-known type of steam boiler. A bank of steam generate ing tubes Il is connected to the lower front por- ,tion of the drum, and a bank of downcomer tubes l2 is connected to the lower rear portion f of the drum.` A row vof steam discharge tubes pipes within this drum as .to render access to the interior `thereof substantially impossible. Furthermore, unless the steam velocities are very low, the steam will entrain large quantities of water from the pools, and it will be difiicult to maintain the pools properly filled or to cause the water to flow-through the pools consecutively in opposition to the steam ow, as contemplated.,

to provide a comparatively simple, compact and inexpensive apparatus which will be highly effective in removing impurities from steam.

I4 is connected to the upper front portion of the drum. The tubes Il serve to deliver a mixture Y of steam and water to the drum in known manner, the steam escaping through the tubes I4,"

, `While the water for the most part separates from the steam by gravity and escapes downwardly through the tubes I2. The present invention is concerned primarily with means as purify the steam before it reaches the outletA tubes I4.

Near each end of the drum there is provided a vertical plate l5 approximately semi-circular -in shape and welded or otherwise secured to the surrounding cylindrical ,i surface ofthe drum. These plates are located inthe upper rear portion of the' drum, so that their free edges are at the front and slope downwardlytoward the rear.

A partition wall I6 extends between the two' plates l5 and is connected to the wall of the drum both in front of the tubes Il and in the rear thereof, thus providing in the upper-portion of the drum a chamber I8 with which the the l steam outlet tubes I4 communicate.r Before entering this chamber, the steam ls forced to pass through a moisture separator I9 which extends through the rear portion of the partition I6. A drain pipe 20 serves to return the separated moisture to the pool of boilerwater in the bottom of the drum. This separator I9 may be of any desired type, one suitable construction being disclosed in the patent application of Max H. Kuhner, Serial No. 225,590, filed August 18, 1938. Most of the foreign matter, whether soluble or insoluble, is removedfrom the steam before it reaches the separator I9. For this purpose there is provided a trough 22 which extends lengthwise of the drum in front of the separator I9 and directly beneath the partition I6. The rear wall of this trough is joined to the partition, whereas the front wall is preferably spaced from the partition, so that the boiler steam pressure is effective inside the trough. A horizontal pipe 24 is mounted Within the trough 22 and extends longitudinally thereof, one end of this pipe passing through the adjacent plate I and connecting with the feed water supply pipe 25 of the boiler. The pipe 24 is provided with a roW of holes 26 in its upper portion, so that the feed water will be distributed along the trough with substantial uniformity. Beneath the trough there is provided a row of steam purifying units 23, each of which 'is so proportioned that it can be introduced through the drum manhole. The boiler feed water is delivered to these units through openings 2@ in the bottom of the trough 22.

Each purifying unit 28 comprises a distributing box 3| from which a group of' conduits 32 extends downwardly. The lower ends of these conduits extend through openings in a bottom plate 33 which is connected to the box 3| by means of two side plates 35, the front edges of adjacent side plates being joined at assembly by splice plates 36 (Fig. 2). The conduits 32 are shaped as hollow rectangular tubes in cross-section, with an open slot 31 in the rear wall of each tube, the front walls of the tubes presenting substantially flat surfaces toward the on-coming steam. The conduits are arranged in rows which, extend longitudinally of the drum, with the conduits in adjacent rows staggered, and they preferably slope downwardly toward the rear of the drum.

The distributing boxes 3| are located directly beneath the trough 22 in position to receive feed water from the openings 28 and to deliver this water to the conduits 32. Preferably the conduits in the front rows receive a greater proportion of the water than those in the rear rows, this result being obtained by tipping the boxes '3i downwardly toward the front and thus increasing the depth of the water above the front row of conduits. Instead of discharging the water from the boxes 3i directly into the conduits 32, as shown in Fig. l, tubes 38 (Fig. 4) may extend upwardly from the conduits into the boxes, these tubes having perforations 39 therein. By varying the number and size of these perforations, any desired proportioning of the water among the conduits may be obtained.

In front of the purifying units 28 there is lpref-- erably mounted a baile 4I (Fig. 1) which slopes upwardly and forwardly. The ends of this baille are connected to the plates I5, and its lower edge is submerged in the water within the drum. The upper edge of the baffle is spaced from the partition wall I6 thereabove to provide apassage for the rearward flow of the steam.

The operation of the invention will now be apparent from the above disclosure. The boiler feed water will be supplied to the pipe at a temperature considerably lower than that of the water in the boiler. From the pipe 25 the feed water will enter the pipe 24 whence it will escape through the holes 28 into the trough 22, and thence through the openings 29 into the boxes 3|. From these boxes the feed wate-r will enter the upper ends of the conduits 32, either directly as ln Fig. l, or through the perforations 39 and the tubes 38 as in Fig. 4, and flow downwardly through these conduits until it is discharged into the water within the drum. The tubes I I will deliver a mixture of water and steam into the front portion of the drum, where most of the water will separate by gravity and eventually flow downwardly through the tubes I2. The steam, with considerable boiler water in suspension, will flow upwardly, and as it passes rearwardly over the top of the baille 4I much of the suspended moisture will be thrown out centrifugally because of the abrupt change in the direction of flow. The steam and the remaining suspended moisture will then ow rearwardly into contact with the first row of conduits 32, and the resulting impingement will bring about a deposit of particles of moisture and suspended foreign matter, and a combining of such particles into larger particles. At the same time some of the steam will be continuously condensing on the outside of the conduits, which are maintained at a temperature below that of the steam by the transfer of heat to the feed water inside the conduits. The resultant condensate will mix with the deposited moisture and dilute the same, and a considerable part of the mixture will descend the front faces of the conduits to the boiler water line, aided by gravity and by the effect of the steam flow on the sloping surfaces of the conduits. Such of the mixture as does not thus escape from the steam will be swept along therewith into contact with the second row of' conduits. The velocity of the steam past each conduit will tend to create a region of reduced pressure within the same, and much of the suspended moisture will leave the steam and be drawn inwardly through the slots 31 into the conduits, where it will mix with the feed water and be carried downwardly and out of the purifier. Condensate will form continuously on the outside of all the conduits 32, and since this condensate is pure water, free from either soluble or insoluble foreign matter, the moisture in the steam will not only be to a large extent removed at each row of conduits, but it will also be diluted more and more at each stage. Thus when the steam finally leaves the purifying units 28, such moisture as it carries in suspension will be substantially pure condensate, with a negligible amount of impurities. Most of this moisture will be removed from the steam as it passes through the separator I9 into the chamber I8. The clean dry steam will escape from the chamber It through the tubes I4.

It will berecognized that the invention pro-v claim as new and desire to secure b'y Letters Patent is:

1. Steam purifying apparatus comprising, in combination with a steam-.and-water drum havinga steam outlet, a series of parallel metal conduits located within the drum and arranged in a means to supply boiler feed water to the interior plurality of rows, the conduitsextending downi wardly across the path 'of the steam as it flows toward the outlet, and means to supply boiler feed water tothe conduits for flow therethrough in amounts progressively decreasing in the direction of steam ow past the conduits.

l2. Steam purifying apparatus comprising a drum having a steam outlet,-a series of metal conduits located within the drum and spaced y apart for the passage of steam between them as it travels toward the outlet, and means to supply boiler feed water to the interior of thev conduits so that there will be a, deposit on the outer surlet passage, a series of metal conduits located l within the drum, the conduits extending downwardly across the said rearward path of the steam and being spaced apart longitudinally ofthe drum to allow the steam to pass between them, and means to supply boiler feed water to the interior of the conduits so that there will be a deposit on the outer surfaces of the `conduits not only of moisture carried in suspension by the steam but also moisture resulting from partial condensation of the steam, the depositedv moisture traveling downwardly along the 'conduits by gravity.

4. Steaml purifying apparatus comprising a drum having a steam outlet, a series of vmetal conduits located within the drum and spaced apart for the passage of steam between them as it travels toward the outlet, and meansto supply boiler feed water to the interior of the conduits,

the conduits being shaped to present substantial-` of the conduits, the conduits being shaped to present substantially flat outer surfaces-toward the on-coming steam so that the steam will impinge thereon and cause agdepositthereon of moisture carried in suspens/ion by the steam as well as moisture resulting from partial condensation of the steam, the conduits being arranged at a sufficiently steep angle to cause the deposited moisture to travel downwardly along the conduits by gravity. l

6. Steam purifying apparatus comprising a drum having a steam outlet, a series of metal conduits located within the drum and arranged in. a plurality of rows acrossV the path of the steam, with the conduits in adjacent rows staggered, and means to supply boiler feed water to the interior of the conduits, the conduits being positioned at afsufciently steep angle to cause gravity flow of the feed water therethrough, the conduits being open at the side away from the on-coming steam so that moisture carried in suspension by the steam may be drawn into the conduits by the eifectof the reduced pressure resulting from the velocity of the steam past the conduits.

'7. Steam purifying apparatus comprising a drum having a steam outlet, a series of parallel metal conduits of approximately rectangular cross-section located within the drum and arranged in a plurality of rows across the path of the steam, with the conduits in adjacent rows staggered, and means to supplyboiler feed water vto the interior ofthe conduits, the conduits being positioned at avsuciently steep angle to cause gravity flow of the feed water :there-l through, the conduits having an open longitudi- 1y flat outer surfaces toward the on-coming steam so that the steam will impinge thereon and cause a depositvthereon of moisture carried inl suspennal slot at the side away from theon-coming steam so that moisture carried in suspension by thev steam may be drawn into the conduits by the effect of the reduced pressure resulting from the velocity of the steam past the conduits.

8. Steam purifying apparatus comprising, in combination with a drum having a steam outlet, a series of parallel metal conduits located within the drum and arranged in a plurality of rows, the conduits extending across the path of the steam as it flows toward the outlet, and means 1 to supply boiler feed water to the conduits for conduits.

iiow therethrough in amounts progressively decreasing in the direction of steam flow past the L V ANDREWS.

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