US2576843A

US2576843A - Heat exchange apparatus

Info

Publication number: US2576843A
Application number: US22215A
Authority: US
Inventors: Lockman Carl John
Original assignee: Rosenblads Patenter AB
Current assignee: Rosenblads Patenter AB
Priority date: 1944-12-30
Filing date: 1948-04-20
Publication date: 1951-11-27
Anticipated expiration: 1968-11-27

Description

Nov. 27 1951 c. LOCKMAN HEAT EXCHANGE APPARATUS Filed April 20, 1948 4 Sheets-Sheet 1 Nov. 27, 1951 c. LOCKMAN 2,576,843

HEAT EXCHANGE APPARATUS Filed April 20, 1948 4 Sheets-Sheet 2 Fig la Nov. 27, 1951 c. LOCKMAN 2,576,843

HEAT EXCHANGE APPARATUS Filed April 20, 1948 4 Sheets-Sheet 5 Nov. 27, 1951 Filed April 20, 1948 C. J. LOCKMAN HEAT EXCHANGE APPARATUS 4 Sheets-Sheet 4 Patented Nov. 27, 1951 HEAT EXCHANGE APPARATUS Carl Johan Lockman, Stockholm, Sweden, as-

signor to Aktiebolaget Rosenblads Patenter,

Stockholm, Sweden Application April 20, 1948, Serial No. 22,215

In Sweden December 30, 1944 The present invention relates to heat exchange apparatus of the surface type for heating, evap orating and like purposes and to a method of operating the same.

More particularly the invention is concerned with such apparatus as serving for transmitting heat from vapours to a scale forming liquid, and in which the paths of the different fluids may be interchanged at intervals during operation in order that any scale formed by the liquid on the walls of either fluid passage during one period should be substantially removed by the dissolving action of the vapours and their condensate when passed through the same passage during a followin period.

The indicated method of removing scale by passing each of the fluids alternately through another one of the fluid passages is obviously a very desirable one since it may be performed practically without stopping operation and the change may be made at shorter or longer intervals as may be desired in any given case without unfavorably influencing either the continuance of operation or the costs, so that the cleaning may be timed to commence when the scale deposits are still very moderate and relatively easy to dissolve.

However, the cleaning capacity of the vapours more or less depends upon and is limited by certain factors of which one of great importance is that they produce a suflicient volume of condensate relative to the surfaces of the walls of the passage to provide continuous and ample wetting of all of the surface of the latter by an evenly distributed flow of liquid condensate, since it is a liquid condensate that provides the most active dissolving agent.

In practice the ideal conditions cannot be secured without special arrangements for the obvious reason, for instance, that the deposition of condensate will be only very slight adjacent to the place where the vapours enter and still less of the condensate will immediately be distributed upon the wall surfaces in that region and possibly only over parts thereof, whereas the flow of condensate will increase more and more towards the opposite end of the vapour passage. Consequently, in case of relatively resistant scale deposits the cleaning action may be quite inadequate near the entrance end while more or less adequate in the central region and rather satisfactory at the opposite end. With such operation, however, the practical value of the method is doubtful or to a great extent reduced because then the incompletely removed portions of scal 4 Claims. (01. 257-1) deposits will increase continually and sooner or later make it necessary to take the apparatus out of operation for a more thorough cleaning by chemical or mechanical means and this will involve excessive costs.

It is an object of the invention to provide means for circulatin condensate through the passages which are used intermittently as vapour passages to secure a satisfactory and more even flow of condensate over the passage walls in order to increase the cleaning capacity and eliminate the drawbacks mentioned.

Another object of the invention is to provide means for distributing circulated condensate in a sub-divided state as by spraying nozzles, for instance, in order to further facilitate wetting of the passage walls and increase the cleaning efficiency.

A further object of the invention is to use the heating vapours in a jet condensor for circulating and distributing condensate as desired.

A still further object of the invention is to cause circulation of condensate as indicated in quantities which exceed the quantity formed by condensation and preferably amount to a plurality of times the amount of the condensate.

Still further objects will be apparent from the following.

Suitable embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a plant with a heat exchanger having a pump for circulating condensate,

Figure 1a shows another arrangement employing an injector instead of a pump.

Figure 2 is a section of the same exchanger shown in Figures 1 and 1a with inlets and outlets for the two heat exchanging fluids, taken along the line IIII in Figure 1,

Figure 3 is a section of the heat exchanger taken along the line. III-III in Figure l, and

Figure 41s a section of the heat exchanger taken along the line IV--IV in Figure 1.

In all figures the same reference characters refer to the same parts.

The heat exchanger I comprises a plurality of parallel heat transmittin walls 2 of sheet metal spaced at equal distances between two side plates 3. Together with the plates 3 and strips 4 the walls 2 form a system of equally shaped parallel and vertical channels I2 and [20. Above and beneath the ends of the strips 4 the walls 2 are extended in a V-shaped configuration so that at the top and the bottom the walls terminate in

oblique edges

5, 5a, 5b and respectively. Each channel is closed along one of its oblique bottom edges, for instance the left one 5a, by means of a strip 6a, and in the same manner, the same channel is closed along one of its top edges, for instance likewise the left one, 50 by means of a strip 6b, although, instead, the right top edge 5b may be closed if desired. The adjacent channels |2a are closed along the remaining bottom and top edges 5, 5b respectively. In this manner alternate channels will be open to alternate sides, and there are thus formed two groups of channels, one group being open to one side, for instance the left one, and the other group being open to the other side, for instance the right one. Covers 1, at both sides closed by the extended side plates 3, enclose

chambers

8, 8a, 8b, 80, at the bottom and the top of the channels 12, Ha. The left-hand chambers 8a, 80 connect the channels l2a of the group open to the left while the right-hand chambers 8, 8b connect the channels I2 of the group open to the right. It is also clearly seen that the right-hand bottom chamber 8 communicates with the righthand top chamber 8b through the channels l2 and that the left-hand bottom chamber 8a communicates with the left-hand top chamber 80 through the channels I211.

The scale forming liquid to be heated may be introduced into the exchanger through a conduit 9, a valve In and an intake II and then passes through the channels l2 whereupon it is withdrawn through the outlet l3, a valve Hi and a conduit l5. In the embodiment shown in Figure 1, a vaporous heating medium may be introduced through a valve 16, conduit l8, a valve |9a (Fig. 2) and an intake l3a into the channels I2a. From the channels l2a' condensate may be withdrawn through the outlet Ha, a valve 23a, and conduit 20, a float chamber or vessel 2|, a conduit 22, a pump 24 (Fig. 1),

conduits

25, 26 and a discharge conduit 26a controlled by a throttle valve 21. The valve 21 is operated from the float 28 by means of a link system 29 so that the valve 21 will close when the level of the condensate in the vessel 2| sinks while the valve will open when the said condensate level rises.

Alternately, the paths of flow of the heated and heating media passing through the heat exchanger may be interchanged so that the liquid will be introduced to the channels l2a through the valve Illa and withdrawn from said channels through the intake |3a and valve Ila. while the vaporous heating medium will be introduced into the channels l2 through the valve I 9 and inlet l3, the condensate formed being withdrawn through the valve 23. Interchanging of the passages may be effected periodically so that channels which are conveying liquid during a given period will be conveying vapour during the next period.

Condensate withdrawn from the heat exchanger, is passed in circulation through the pump 24;\conduits 2|, 32 and valve 33 or through conduit 32a and valve 33a into a condensate distributing pipe 34 or 34a, respectively. During this cycle of operation the valve 39 in the conduit above the conduits 32, 32a is closed. The

valves

33, 33a are set so as to supply the condensate to that one of the pipes 34, 34a which is arranged in the top chamber to or Go conveying the heating medium. The condensate distributing pipes are closed at their ends 85 and 35d, respectively, and provided with a number of nozzles 38 adapted to spread the condensate over the whole top of the heating surfaces of the channels. Thus, during a given period condensate will be flooded over said surfaces of the channels I2 conveying the heating medium, so as to remove scale therefrom precipitated from the liquid during the preceding period when said channels were conveying liquid. Owing to the fact that the channels are directed vertically and their heating surfaces likewise are vertical and since the heating surfaces have a substantially uniform width from the top to the bottom, the condensate distributed over the top part of the surfaces will continue to flood all remaining parts of the heating surfaces while flowing downward, so that the whole surfaces will be cleaned completely and very effectively.

Alternatively, as shown in Figure 1a, the vaporous heating medium may be introduced into the system through the valve "Send an injector 38 communicating with the conduit I8 so as to effect the circulation of the condensate by means of the suction action of the vapour. In this manner the condensate will be supplied to the heat exchanger through the conduit 25, valve 39 and conduit l8 intimately mixed with the vapour. In this case the injector will serve both as circulating pump and as condensate distributing means so that the pump and distributing device may be omitted if desired.

In some cases it may be of advantage to circulate a quantity of condensate exceeding the quantity formed by new condensation in the heat exchanger. Thus, in starting the operation of the heat exchanger the condensate will be circulated and withdrawal of condensate will occur automatically as soon as the total quantity of the condensate is sufllcient for causing the float 28 to open the valve 21.

Within the scope of the invention there can naturally be made further changes and modifications in its application in addition to those illustrated or described above. For instance, different pairs of branch valves for changing the flow paths of the fluids may be replaced by threeway valves or the main return pipe for condensate may terminate in the main supply pipe for heating steam. Of course the heat exchanger may be of any suitable construction but obviously it is preferred to use a laminated type or such a one in which the different fluid passages may be made substantially uniform in shape with fairly equal proportions.

Thus, it is understood that the invention is not limited otherwise than by the appended claims.

What I claim and desire to secure by Letters Patent is:

1. In a heat exchange apparatus having passages for conducting a heating medium and a scale forming liguid in heat exchange relation, said passages being formed between substantially equally spaced and parallel plate parti-' tion walls and each of the passages being open at the top and bottom, a valved inlet connection for conducting said heating medium to alternate passages, a valved outlet connection for discharging condensate from said heating medium from said passages, a valved inlet connection for conducting said scale forming liquid to the remaining passages, a valved outlet connection for conducting said liquid from said passages, valve means for interchanging the paths of flow of said heating medium and said liquid, a collecting device for receiving condensate discharged from said passages, a valved outlet connection from said collecting device, valved connections from said outlet connection to the open top ends of said passages, and means for selectively circulating condensate through said last named connections and discharging the circulated condensate in subdivided and distributed form on the topmost parts of the walls of said passages to remove scale deposits therefrom.

2. In a heat exchange apparatus as described in claim 1, a valved drainage connection disposed in the outlet connection of the collecting device, means responsive to the level of condensate in said collecting device for automatically controlling the operation of said valved connection for withdrawing new amounts of condensate formed in the apparatus, and a circulating pump for circulating condensate from the collecting device into the topmost part of said passages.

3. In a heat exchange apparatus havin passages for conducting a heating medium and a scale forming liquid in heat exchange relation, said passages being formed between substantially equally spaced and parallel vertical partitions and each passage being open at the top and the bottom, a valved inlet connection for conducting said heating medium to the open top ends of alternate passages, a valved outlet connection for discharging condensate from said heating medium from said passages, a valved inlet connection for conducting said scale forming liquid to the inlets of the remaining passages. a valved outlet connection for conducting said liquid from said passages, valve means for interchanging the paths of flow of said medium and said liquid, a collecting device for receiving condensate discharged from said passages, a

valved outlet connection from said collecting de- Patent No. 2,57 6,843

vice, valved connections from said outlet connection to the open top ends of said passages, an injector associated with said last named valved connections, and means for conducting vaporous beating medium through said injector for selectlvely circulatin condensate from said draining device to the heating medium supplied to said passages whereby condensate is distributed on the walls of said passages in a subdivided state to remove scale deposits therefrom.

4. A heat exchange apparatus as described in claim 3 in which the injector is positioned substantially adjacent the inlet connections to the passages in the heat exchanger whereby a mixture of condensate and heating medium will be sprayed directly upon the walls of said passages.

CARL JOHAN LOCKMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,006,197 Frasch Oct. 17, 1911 1,970,296 Fleisher Aug. 14, 1934 2,376,505 Rathbun et al May 22, 1945 2,488,598 Lockman Nov. 22. 1949 2,490,750 Grewin et al Dec. 6, 1949 2,490,759 Tyden Dec. 6, 1949 FOREIGN PATENTS Number Country Date 64,286 Denmark Jan. 28, 1946 November 27 1951 CARL J OHAN LOCKMAN It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 63, for conduits 21 read conduits 25 column 4, line 48,

before type insert plate;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 18th day of March, A. D. 1952.

I scan] THOMAS F. MURPHY,

Assistant Gammieezloner of Patents.