US2278192A - Thermic process - Google Patents

Description

March 1942- e. s. CANTACUZENE 2,278,192

THERMIC PROCESS Filed May- 9, 1939 ozyes 6. CanZacu; e

Patented Mar. 31,1942 I 4 THERMIC PROCESS Georges Servan Cantacuzne, Paris, France Application May 9. 1939, Serial No. 212,735 In France May 27, 1938 2 Claims.

for preventing the loss by evaporation of volatile liquids, such as, painting the reservoirs of the volatile liquids a light color in order to reduce the absorption of solar heat, making the reser-.

voirs air-tight in order to prevent renewal of the air, floating top surfaces restricting the available surface of evaporation, recoving the vapors expelled from the reservoirs, making the reservoirs of spherical shape so as to resist a very strong pressure, compensation gasometers etc. These various methods are either too expensive or are imperfect. It is an object of the invention to avoid these disadvantages.

The phenomena taking place in a reservoir under the effects of the sun, the wind 'and'the rain are very complex and consist in evaporations and condensations, convection currents, difiusions, etc. These various phenomena do not present any direct interest The most important phenomenon to be counteracted is the inlet of exterior air during the contraction of the gases in the reservoir and the outlet of the air in the reservoir more or less saturated with gasoline vapors during the expansion of the gases. It is an object of the present invention to annul or greatly reduce the expansion and contraction of the gases during the day and night by alternately introducing or withdrawing heat from the gases.

A further object of the present invention is to maintain the pressure of the gases in the reservoir between the limits of pressure which would cause the opening of either the inlet valve or the outlet valve.

A still further object of the invention is to control the pressure of the gases in the reservoir by means of a manometer cooperating with a refrigerator for cooling said gases and in some) cases cooperating also with a heater for heating said gases.

With the above and other objects in view which will appear from the detailed description below a preferred embodiment of the invention will be described.

The figure upon the annexed drawing illustrates the invention in vertical section diagrammatically.

The present invention is based upon the following fundamental considerations. The evaporation of a liquid depends in thefirst place upon its particular vapor tension which a function of the temperature. Every volatile liquid only evaporates while absorbing heat, on one hand in the form of specific heat when the temperature rises and on the other hand inthe form of latent heat of vaporization when it evaporates.

From the above it follows that the reservoir is a boiler whose energy is furnished by the sun. Therefore if it istaken into consideration that the heat necesary for the ,vaporization of a combustible liquid, such as is involved here, is much-less than the heat that the vaporized liquid is capable of giving by its own combustion,

the conception of the present invention is arrived at logically which consists in annulling the calories of vaporization by the withdrawing of heat from the reservoir according to a predetermined method and apparatus.

For example, a kilogram of gasoline, lost by evaporation, has required in order to be heated,

- vaporized, and then expanded to the vapor state,

value is on. the average about grand calories. A kilogram of gasoline, if it were burned, would give 10,000 to 11,000 grand calories which are capable of producing about 1500 to 2000 grand cooling calories in a refrigerator of slight efliciency which will annul the loss by evaporation of a quantity of gasoline 10 or 15 times greater.

The above comparison between the combustion heat of the gasoline and the heat corresponding to the evaporation has been made in order to more fully understand the importance of the invention. Practically the energy put to work in order to produce the cooling calories will advantageously be supplied by an electric current.

In the drawing, a reservoir for a volatile liquid such as gasoline is shown at I having a top 2 and an exhaust valve 3 located in the top 2 for permitting the escape of the gases 4 when the pressure thereof reaches a predetermined point, say 20 grams per square centimeter, and serving for the inlet of air when the pressure of the gases 4 decreases to 5 grams with relation to the atmospheric pressure.

In the reservoir the level of the volatile liquid is shown at 5 and a refrigerator of any desired type, preferably operated by an electric current, is shown at, 6. Located in the gases 4, preferably in the upper portion thereof, is a heat exchanger 'I operated by the refrigerator 6 for supplying cooling calories to such gases or withdrawing the heat therefrom. A heat exchanger 8 is also operated by the refrigerator 8 for dissipating the heat calories.

The fluid, whose expansion or evaporation according to the type of refrigerator used, and

which brings about the cooling effect of the heat exchanger 1, is led by a heat insulated conduit 3 to the heat exchanger I and then after having produced the cooling effect is led back to the refrigerator 3 by a heat insulated conduit II.

A pipe ll connects the gasenclosure with a manometer l2 which operates the control element l3 for starting and stopping the operation of the refrigerator 6.

The various elements above mentioned are individually known and may be of any appropriate type. For example, the refrigerator 6 may be an ammonia refrigerator operated by an electric motor, the heat exchanger 1 may be a flanged radiator, the exchanger 3 may be a runningwater type of exchanger, the manometer I! may be a manometer of appropriate type which will operate for example a mercury switch l3 for opening or closing the current of the electric motor of the refrigerator 6. The manometer I! which controls the switch I3 may be set was to start and stop the refrigerator at predetermined pressure limits relative to the setting of the valve 3 which in turn is ordinarily set in accordance with the resistance of the reservoir l, the climate and the volatility of the particular liquid in storage.

The operation of the invention is as follows: The reservoir I is filled with gasoline for example and the gases 4 may be under a pressure which is slightly lower than the pressure which would cause an opening of the valve 3 which is closed. The pressure which would open the valve 3 is assumed to be 20 grams per square centimeter.

If the filling of the reservoir has been finished before nightfall then during the night the gases 4 will ordinarily be cooled and the pressure thereof will be lowered proportionately and ordinarily the inlet valve will permit a certain quantity of outside air to, enter. Then on the following morning the sun will reheat the gases and consequently their pressure will increase proportionately, but beforesuch pressure exceeds the value of 20 grams for which the valve 3 has been set to open, the manometer I2 operates the control element or switch l3 which has been set for 19 grams and the refrigerator 6 is set in operation. Thereupon the exchanger 1 will withdraw heat from the gases 4 and may even condense such gases which consequently causes a fall in the pressure of the gases. When the manometer l2 indicates a pressure lower than 15 grams, if the manometer has been set at such value, the

withdrawal of heat by the exchanger 1 will cease.'

Such operation will be repeated during the course of the day and upon following days in the same manner. Accordingly, there will be no further'losses by evaporation.

If desired, in addition to the combination of elements set forth above, there may be a heater or radiator [4, preferably electric, which is also located in the gases 4 and preferably slightly above the highest level of the liquid in the reservoir. The radiator i4 is supplied by the conductor l5 which is controlled also by the manometer l2 so as to close the electrical circuit whenever the .pressure descends to a given value and break the electrical circuit whenever the pressure ascends to a certain given value which is lower than that at which the refrigerator 3 comes into operation. However, as a practical matter and in temperate climates the addition of the radia-' tor I 4 is not of particular interest. The utility of the present invention resides'in the fact indicated above that the energy spent for producing the heat withdrawal, for example the electrical current, is far less than that which represents the liquid lost by evaporation. Naturally the power and consumption of energy of the refrigerator will be, for a given reservoir, somewhat less as the reservoir is better protected against the absorption of the sun's heat and against thermic changes of the surrounding medium.

Furthermore it is optional whether the refrigerator is installed at the side of the reservoir or upon the top surface thereof. Also a separate installation may be made for each reservoir or a central refrigerator may be provided for a group of several reservoirs. Also, if the gases from several reservoirs are placed in communication with a single reservoir, a partial distillation of the volatile product separate condensation.

I claim:

1. The method of avoiding evaporation losses from a volatile liquid in a storage tank or the like, which comprises an external refrigeration apparatus connected with inner refrigerating means in heat transfer relation with the gas space of the tank, so arranged as to permit the condensate to trickle back to the liquid level, in combination with pressure controlling means maintaining automatically the pressure in the as space between predetermined limits by operating the refrigeration apparatus whenever the vapor pressure attains the upper limit and stopping said refrigeration apparatus when the vapor pressure attains the lower limit; heating means in heat transfer relation with the gas space of the tank, located slightly above the highest level of the liquid in the tank, controlled by said pressure controlling means and so arranged as to heat the vapor when the pressure drops below a predeterminated limit.

2. The method of avoiding evaporation losses from a volatile liquid in a storage tank or the like, which comprises an external refrigeration apparatus connected with inner refrigerating means in heat transfer relation with the gas space of the tank, so arranged as to permit the condensate to trickle back to the liquid level, in combination with pressure controlling means maintaining I gas space between predeterminated limits by operating th refrigeration apparatus whenever the vapor pressure attains the upper limit and stopping said refrigeration apparatus when the vapor pressure attains the lower limit; in combination with usual breather Walves on the tank top regulated ,to permit flow of gases from the tank to the atmosphere when the tank is filled and flow of air into the tank when the tank is emptied.

GEORGES SERVAN CANTACUZENE.

may be secured by a automatically the pressure in the

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