US2508119A

US2508119A - Method of operating heat exchangers

Info

Publication number: US2508119A
Application number: US593457A
Authority: US
Inventors: Lockman Carl Johan
Original assignee: Rosenblad Corp
Current assignee: Rosenblad Corp
Priority date: 1944-06-05
Filing date: 1945-05-12
Publication date: 1950-05-16
Anticipated expiration: 1967-05-16
Also published as: DE861540C

Description

May 1950 c. J. LOCKMAN 2,508,119

METHOD OF OPERATING HEAT EXCHANGERS Filed May 12, 1945 Ti /4 fie a Z0 56 /5 Patented May 16, 1950 METHOD OF OPERATING HEAT EXCHANGERS Carl Johan Lockman, Enebyberg, Sweden, as-

signor, by mesne assignments, to Rosenblad Corporation, New York, N. Y., a corporation of New York Application May 12, 1945, Serial No. 593,457 In Sweden June 5, 1944 3 Claims.

The present invention is concerned with the operation of heat exchangers with two separate channel systems and has particular reference to such cases in which one of the heat exchanging fluids may cause incrustation of the heat transmitting walls while the other fluid is capable of dissolving and removing the incrustations as, for instance, when using condensing steam or hot water which in most cases constitute the other In such case it is known to clean the heat exchanger, practically without interrupting the heat exchange process, by passing different fluids alternately through the respective channel systems so that the channel system which has conducted the crust forming fluid during one period, will during a subsequent period conduct the crust dissolving fluid, which will remove the incrustations formed during the previous period, if the alternations of fluids are suitably timed.

It has, however, been observed that the incrustation will generally grow considerably faster and thicker than elsewhere at the hottest part of the channel systems which is mostly at the top or the bottom where the heat delivering fluid is generally admitted. This is obviously a considerable drawback in as much as it requires more frequent alternations of fluids than if the encrustation were more evenly distributed. However, a short cycle is undesirable because the alternation of fluids involv some loss of time and fluids and should therefore take place as seldom as possible.

Furthermore, when the heat delivering fluid consists of condensing steam, as is most frequently the case, the cleaning efiect thereof upon the incrustations will be considerably less than the average in the neighborhood of the inlet opening for the steam, which is normally at the top or bottom part of the channel systems because it is actually the condensate which is active in dissolving the crust deposits and necessarily there will be but little condensate present near the steam inlet and accordingly the cleaning effect in that zone will be rather slow whereas it increases as the flow of condensate increases towards the discharge end of the channel system. The consequences thereof will be exactly the same as above stated to be caused by the uneven thickness of the crust deposits and thus the difficulty will be doubled.

It is an object of the present invention to overcome the imperfections mentioned so as to reduce the frequency of alternations of fluids and to perform this by turning over the heat exchanger at suitable intervals so as to cause its top and bottom portions to change places.

According to the invention the turning of the heat exchanger may take place at any suitable moment, either simultaneously with alternation 2 of fluids between the channel systems or independent thereof and between two subsequent alternations and possibly at intervals between repeated alternating periods.

Suitably the heat exchanger to be subjected to the present operating method should be made symmetrical in order to facilitate the different procedures and measures required therefor, and further it should be provided with horizontally disposed supporting pivots fitted in bearings and connected, for instance, with a suitable gearing for turning the apparatus.

The invention will be further illustrated by three embodiments of apparatus for carrying out the same which are shown in the accompanying drawing, of which Fig. 1 is a more or less diagrammatic view, partially in cross-section, of one form of heat exchanger arrangement suitable for carrying the invention into effect;

Fig. 2 is a view showing the exchanger of Fig. 1 in reversed position;

Fig. 3 is a view similar to Fig. 1 showing another embodiment of the invention; and

Fig. 4 is a view similar to Fig. 1 showing still another embodiment.

In the drawing the numeral l designates the heat exchanger being in this case a common tubular apparatus with the heat transmitting surface formed by a set of tubes 2. The apparatus is carried by the pivots 3 so that it can be rotated around an horizontalaxis through the centre of gravity by means of gearing 4.

In the position shown the apparatus is supplied with heating steam through the inlet connection 5 to the conduit l0 communicating with the channel system formed outside the tubes and therefrom the condensate is discharged through the conduit I I to the outlet connection 6, whereas a crust forming liquid to be heated is introduced from the inlet connection I to the conduit I2 communicating with the channel system formed inside the tubes and leaves the same through the conduit l3 to the outer connection 8. Under such circumstances the highest temperature of the heat transmitting surface will prevail at the upper portion and in that zone therefor the crust deposits will grow more rapidly and thicker than elsewhere while the cleaning effect will be comparatively weak in the same zone for reasons referred to above. To compensate for this in accordance with the invention the apparatus is at suitable intervals turned over after interrupting the flow of fluids and loosening the

connections

5, 6, I and 8, and this being done the

connections

5, 6, I and 8 are again attached to the conduits l2, l3, l0 and II, respectively, as shown in Fig. 2. Then each fluid will be conducted through the other of the channel systems as compared with the previous position shown in Fig. 1, so that any crust deposits formed by the liquid on the inside 01' the tubes during the former period will be dissolved and removed by steam and condensate within the tubes during a subsequent period. Such operating cycle may be repeated any desired number of times, and by suitable timing the turning of the apparatus and alternation of fluids between the channels the transmitting surfaces will be maintained substantially clean in a very practical and efllcient manner. I

In the embodiment shown in Figs. 1 and 2, reversal of the position of the exchanger will operate to simultaneously change or alternate the flow of the fluids through the different channel systems, but as previously mentioned this may not be essential or even desired and in Fig. 3 an arrangement is shown in which reversal of position of the exchanger may be efiected independently of change of the fluids through the different channel systems. In this embodiment the construction of the exchanger is as previously described, but in this instance the inlet conduit l and the outlet II for one fluid are on the same side of the exchanger, whil both the inlet conduit i2 and outlet conduit lit for the other fluid are on the opposite side of the exchanger. As will be evident from the drawing, reversal of the position of the exchanger will not change the channel systems through which the respective fluids pass but will change the end of the exchanger at which the scale formation s most rapid and the end where its removal is most effective. For changing the fluids from one channel system to another, suitable connections (not shown) are provided for supplying, as desired, either one or the other of the fluids to the inlet conduits I0 and I2 respectively.

In Fig. 4 another arrangement is shown whereby the exchanger may be turned with or without simultaneous change in the flow paths of the fluids. In this arrangement the steam inlet conduit I0 may be connected either to the tube system through the conduit Illa or to the system outside the tubes through conduit lob, these conduits being controlled, respectively, by valves I4 and I5. Likewise the condensate conduit H may be connected to either system through conduit Ha or I lb, these conduits being controlled respectively by valves I6 and i1. Similarly, the flow 0f the other fluid from the inlet conduit II to the outlet conduit [3 may be directed through one or the other of the channel systems via the conduits I 2a and I 2b, controlled respectively by valves [8 and I9, and conduits Ila and lib controlled respectively by valves 20 and 2|. If, for example, with valves I5, I], I 8 and 20 open and valves I4, l6, l9 and 2| closed, reversal of the exchanger without changing the valves will not change the channel systems through which the respectiv fluids flow. On the other hand, opening the closed set of valves and closing the open set will operate to change the flow of the fluids to the alternate channel systems. Obviously reversal 0f the exchanger and changing of the setting of the valves may be made independentl of each other or concurrently to secur any desired cycle of operation. While in all the embodiments shown by way of illustration rigid pip connec- I ters Patent is:

tions have been shown, it will be evident that flexible connections may be employed in case it is desired to, reverse the exchanger without interruption of fluid flow.

Naturally the invention is not confined to the 1. A method of operating heat exchangers with two separate channel systems in heat exchange relation, comprising the steps of passing an encrustation depositing fluid through one channel system, passing a vaporous fluid which forms a scale removing condensate through the other channel system from the top to the bottom end thereof, alternating the channel systems through which each fluid flows, and turning over the heat exchanger at suitable intervals so as to cause its top and bottom portions to change places, said vaporous fluid being after such a turning over operation entered into either channel system at its top end which constituted its bottom end before said turning operation.

2. A method of operating heat exchangers with two separate channel systems in heat exchange relation, comprising the steps of passing an encrustation depositing fluid through one channel system, passing a vaporous fluid which forms a scale removing condensate through the other channel system from the top to the bottom end thereof, directing the flow of each fluid during subsequent periods first through one and then through the other channel system, turning over the heat exchanger at any desired moment of such a flow period so as to cause its top and bottom portions to change places, and maintaining the same flow through the same channel systems with unchanged flow directions immediately before and after the turning over operation, whereby said vaporous fluid will on entering from the top into the respective channel system be received alternately at opposite ends thereof.

3. A method of operating heat exchangers with two separate channel systems in heat exchange relation, comprising the steps of passing an encrustation depositing fluid through one channel system, passing a vaporous fluid which forms a scale removing condensate through the other channel system from the top to the bottom end thereof during a selected period of time, alternating the channel systems through which each fluid flows during subsequent periods between any consecutive such flow periods, interrupting the flow while turning over the heat exchanger so as to cause its top and bottom portions to change places, and then re-admitting the flow but changing the paths of each fluid from one to the other channel system, said vaporous fluid being thereafter received into the respective channel system at the end thereof which has been moved from bottom to top position.

CARL JOHAN LOCKMAN.

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

UNITED STATES PATENTS Number Name Date 1,006,197 Frasch Oct. 17, 1911 1,464,705 Goosmann Aug. 14, 1923 2,188,245 Middleton Jan. 23, 1940 2,380,604 Melton July 31, 1945