US1429149A - Heat interchanger - Google Patents

Description

A; R. LAWRENCE.

HEAT INTERCHANGER. PPL ICATION FILED OCT. 18, 1920.

Patent/ed Sept. l2, 192%2.

ALMoN- n.. LAWnENcnlor QUINCY, MASSACHUSETTS, ASSIGNOR To ENGINEERING DEVELOPMENT COMPANY, ,orf BOSTON, MASSACUSETTS, A CORPORATION or MASSACHUSETTS. y

y MEAT iNTERcHANGE'n.

Application led October 18, 1920. Serial No. 417,605.

To all uzont may concern.'

Be it known that I, ALMON RLAWRENQE, a citizen offthe AUnited States, residing` at Quincy, in the 'county of Norfolk and'State, .of Massachusetts, have invented new and useful Improvements in Heat Interc'hange'rs,v

of whichvthe following is a specification;

Thepresent invention relates to heat interchangers of the tubular type wherein liquid is caused to ow through tubes which are surrounded by a fluid medium in. an enclosed space (hereinafter referred to as a "receiving chambe) for the purpose of veffecting transfer of heat between such medium and liquid when their respective temperatures .are different. Such a heat inter changer is exemplified in a surface condenser for steam plant use,'having water tubes by which cooling water is conducted through the interior space or chamber of a shell adapted to receive steam. Asthe invention is principally intended for the uses of steam condensers, and probably has its greatest value in that connection, I will in the following specification explain andv de.

' scribe its characteristics, yfunctions and utility with reference to such a condenser.

It has been observed in theoperation ofsteam condensers of the tubular type as heretofore'made. that their eiciency in condens.-y

ing steam is substantially less than4 -what should be the maximum, having `regard tol the` temperature. and quantity of cooling. f water, the area ofcoolingsurface, and other known factors; and that Serious corrosion occurs 4in the entrance ends of the tubes. I believe that I have discovered the cause 'of these diticulties; and on my discovery as a basis I have devised a means forovercoming such diiculties, by removing the cause thereof, which has been proved by practical experience tobe effective for the purpose.

As being helpful to an understanding of the characteristics and utility of the inven tion, I will first state the essentials of ,my discovery as follows.

The cooling water used ina condenserisfirst delivered to a chamber at one end of the condenser shell, into which chamber .the tubes open through a tube sheet which parow of liquids through an orifice.

titions off the chamber from the steam space of the condenser. The stream of water in passing from the chamber, where it exists After contracting to its minimum diameter, the

water jet expands and fills the,tube but where rthe contraction occurs, there is an' open space bet-ween .the jet and the surrounding part of thev tube, wherein a partialvacuum exists. Oxygen and other gases car'- ried by thew'ater are caused/*by the vacuum to occupv the space'within'the tube aroundthe contracted jet, and thecgas accumulation retards the'velocity of the jet, causes or tends to cause eddies in the water, corrodes the tube, and impedes heat conduction.

The invention which I am' about. to de- -scribe in detail and claim consists in a means for preventing the formation of avacuum" or gas pocket betweenfthe contracted jet of t water andfthe surronding walls'of the tube.

This means may be embodied in a varietyv of forms, each involving a constrictionof the interior of the tube, o n lines conforml ing to thecontraction curve ofliquid flowing 'through an orifice to less than the diameter of its entrance orifice in that part of the .tube where the contract-ion'of the jet'occurs, that is, at or near the entrance of the tube. Such constriction is best accomplished by adding or applying a separate piece having a -bore which is sodesigned as to pro duce the desired constriction; and may also be acfcomplished by suitably Shaping the tube itsel modes and forms in which the invention l The drawingsv herewith furnished- -illustrate graphically some of the possible involved in a constricted tube adapted for i In the drawings, Figure 1 is sectional viewV of a. surface condenser to illustrate the `heat interchange between fluids may be embodied. A

'application of the invention in; one,` of the 1 environments for which it is particularlydesi'gned and in which it has especial utility.

Figure 2 is a sectional view enlarged of' y,the entrance end of ay tube, such as a condenser tube, equipped withone specific form or embodiment of the invention.

Figure 3 is a similar view of'another form or embodiment of the invention.

Figure 4 is a sin'iila-r view of` a4 further form of the invention. v

Like reference characters designate. the same parts in all the figures.

A typical surface condenser is conventionally shown in vFigure 1, the intention in regard -thereto being not so much to show a specific heat interchanging apparatus as to illustrate by reference to a species the nature of the apparatus wherein the invention has its special utility. But assuming for the purposes of explanatory description that the apparatus depicted is a steam condenser, the essential parts comprise a vshell .a having heads b and c, an inlet d for steam and an foutlet e for the condensed water, connections f and g through the heads for admission -and exhaust of cooling water, interior tube sheets l1. and i, and tubes lc. 'llhe tube sheets separate the interior of the shell into a central steam space or receiving chamber wherein the external connections a? and e open, and water spaces at the ends into which respectively the connect-ions f and 'g open. rllhe tubes are mounted at or adjacent to their ends in the tube 'sheets in a water and steam tight manner, being conveniently screwed or expanded, or otherwise rigidly secured in one ofthe tube sheets and having slip joints, through stutiingboxes, with the other of the tube sheets. llt may be-assumed here that the cooling` water enters the right hand water chamber through the connection f,-

and that the tubes have slip joints in the right hand tube sheet It. Figure 2 shows in detail one of the types of slipy joint and stutling box used in apparatus of this character. The tube-receivinghole in the tube sheet is of a diameter fitting freely about the tube at the inner'side ofthe sheet,

fand is enlarged at the outer side and is tapped to receive a threaded gland Z. Packing m is confined between thegland and a shoulder in the hole, and is compressed in the usual manner to `make a fluid tight slip joint with the' exterior of the tube..

In the condensers heretofore used, where there is no substantial di'erence between the diameter of the tubes at their entrance ends and at other points,l contraction of the jets flowing into the tubes from the water space occurs as explained in the introductory part of this specification, with resulting loss of efficiency. l have overcome the objectionable eects which result from such contraction of the jets by so constricting the tubes that they are entirely filled with the water which passes through, in the part where the jet is contracted, as well as elsewhere. The form of constriction embodying my inthe tube.

. 'llhe mouth or entrance end of this bore is therefore wider than the interior of the nozzle; and the length of the nozzle and the shape of `its bore approximate to the shape andl length of the contracted section of a jet of liquid flowing from an orifice of the same size as the entrance to the nozzle, under pressure of a head ,approximately the same as the pressure by which the cooling water is forced through the tubes. Consequently the water yHowing into the tube completely ills the bore of the nozzle, and in enlarging after lleaving vthe constricted area of the latter, it completely fills the uniform diameter of the tube throughout its entire length. rll`hus no opportunity exists for a vacuum to be formed, no eddies occur in the water stream,

AVgas can not collectbetween the stream and the tube, corrosion in the entrance end of the tube .is avoided, the rate of flow ofwater through the tube is increased, the power required to force the water through the tube is reduced, and the greatest possible eiciency of heat transfer occurs between the water stream and the vapor` in the steam space.

l/Vhen the 'nozzle is applied to the tube it becomes virtually a part of the tube and forms a constriction or contracted zone of gradually decreasing and then increasing diameter within the mouth 'of the tube. lln the form now bein described the constriction is `smaller in iameter than any other part of the tube, not only smaller than the entrance orifice or niouth, but also smaller than that part of the tube whichthe water traverses'after leaving the constriction.

Sleeves or nozzles equivalent to the nozzle sleeve 'n maybe manufactured in sizes and forms vappropriate to condensers of varioustypes and capacitiespperating under various conditions of water 'pressure and so forth, and may be applied to such condensers already in service as well as to condensers in course of being built. rlheir application to condensers in service involves no more difficulty than is required to remove the head and apply the nozzles to the tubes then exposed. The insertedA noz. zles may be held in place vby friction or secured in any other suitable manner to prevent their becoming dislodged from 'any cause, s uch as the violent movement irnparted to marine condensers by the pitching of the vessel in a heavy sea.

An example of a nozzle associated with a tube and having the "characteristics above lll@ defined, with the exception that the nozzle is not actually inserted in theJ tube and that v its least diameter is the same as the bore of the tube, is' shown in Figure 4 and designated n. vThis rvnozzle has the same enlarged mouth and the Acontracted bore, the walls of which change diameter gradually and have the essential relation to the contraction curve of a jet, as already described. This form of nozzle' may be secured -in the tube sheet, and as a convenient means for mounting it, it 'may be combined With the gland, whereby it is a combined gland and nozzle. Other modes of attachingv or associating the nozzle with the tube will readily occur to those skilled in the art.

The added or inserted nozzle evidently can be applied to condensers: already in service Without requiring any change in the structure or form of the tubes.

Figure 3 shows the invention embodied in an integral tube k1 without an inserted or applied lnozzle. Here the entrance end k2 of the tube is extended beyond the tube sheet into the water space, and is enlarged on such lines of curvature-that the Walls leading from the enlarged orifice to the bodyl of the 4tube are curved conformably tothe contraction curve of a jet flowing under 'head through said orifice.

It" is not to be assumed ing detailed description that the constriction provided as described must .be placed upon that end of the tubevvvhich makes av slip-joint with the tube sheet, or that the constricted entrance end of the tube must be `capable of sliding in the tube sheet. On

the contrary the tube may be rigidly fast i into which said tubes open at from the forego-i' from an orifice, and are at its constricted or entrance end tothe adjacent tube sheet, andA any necessary relative movement of the tube provided for at its other end.

lVhat I claim and desire to secure by Letters Patent is 1. A heat interchanger having a receiving chamber, ing through saidchamber, and a liquid chamber into which said tubes open at one end, those ends of the tubes which open into said liquid chamber and into 'which the liquid 1s designed to enter having bores which gradually contract in diameter from their entrance orifices and are subsequently enlarged, on longitudinallines conforming substantially to the contraction and enlarge? ment of a jet of liquid flowing under a head through an orifice into a tube.

'2. A heat interchanger having a receiving chamber, liquid conducting tubespassing through said chamber, a liquid chamber one end and nozzles fitted in those ends of the tubes which open into said liquid chamber and into which the liquid is designed to enter, said nozzles having bores lwhich diminish from the entrance 'orifice to a constricted zone smaller in diameter than the bore of.

theassociated tube, on longitudinal smooth. curves conformin of a jet of liquid issuing under pressure from the constrictedV zone to a diameter lapproximating the bore of said tube.

In testimonywhereof I have afiixed my.v

signature. Y ALMON LAWRENCE. 1

liquid conducting tubes passto the contraction .curves gradually enlarged

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