US1605793A - Condenser - Google Patents

Description

Nov. 2, 1926. 1,605,793

F. T. SNYDER CONDENSER Fil'ed Nov. 15 1923 Patented Nov. 2, 1923.

FREDERICK T. SNYDER, OF NEW CANAAN, CONNECTICUT.

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Application filed November 15, 1923. Serial No. 674,984.

This invention relates to condensers and more particularly to the type of condensers in which a small amount of vapor is to be condensed out of a large volume of incondensable gas. When the ordinar type of surface condensers is used for suc purpose it has been found that an enormous increase of condensation surface is required for each unit of vapor. The amount of surface is several hundred times that required for condensable vapor without admixture with permanent gases. This great reduction in the efiiciency of the condensing surface in the case of the mixture of permanent gas with the condensable vapor is due to the property which the permanent gas has of at taching itself to the condensing surface and actin both mechanically as an obstruction and t ermally as a heat insulator. This insulating effect is much greater than the simple thermal resistance of the attached gas bubbles themselves, due to the great difliculty that the heat experiences in getting to the condensing surface from the attached gas bubbles and to the gas bubbles from the liquid film of condensed vapor outside of the gas bubbles. These contact. resistances to the flow of the heat from the vapor are many times larger than the heat resistance of the gas itself in the bubble.

In the condenser of my invention the cooling liquid and the mixture of vapors and gases to be cooled are both on the same side of the condensing surface and consequently the heat absorbed does not have to flowthrou h the condensing surface and it is immaterial whether gas bubbles accumulate on the cooling surface.

In many industrial ap lications of con densation, it is desirable t at the condensation be serial, different vapors of different boiling oints being condensed out progressively. t is also often desirable that these separated fractions should each be as pure as possible; as free 'as may be from the fractions with boiling points above and below those of the separatin fraction. To this end the condenser shou d have a high power of fractionation.

It is the object of the invention, there fore, to provide a condensing apparatus in which the process of separation and condensation may be carried out effectively and uickly, and in which the various units of t e apparatus will be grouped into a compact and organized whole such as will permit of the interchange of media for the "pur ose of conducting the separation and ess is shown,

The figure is a diagrammatic view showing the various units of the apparatus grouped and connected for operation.

Referring more particularly to the drawing, 1, 2 and 3 are vertical circular towers. Across each tower is a perforated partition 4, 5 and 6. On these partitions is sup orted filling material 7, 8 and 9. This filing is usually in the form of small earthenware rings. The object is to expose the maximum amount of surface for each cubic foot of tower space. Onto this filling is sprayed cooling fluid .by means of pipes 10, 11 and 12. The mixture of gas and vapors to be condensed enters'tower 1 through the gas pipe 13, passes up through the fillin and into tower 2 by pipe 14. Then up t rough the filling in tower 2 and into tower 3 by pipe 15. Passing up through the filling material 9 in tower 3, the residual gas leaves the condenser system by the exit gas pipe 16.

' The movement of the gas and vapors through the towers is brought about by means of an exhauster 17, into which exit gas ipe 16 discharges and from which the resi ual gas is carried by pipe 18 to industrial uses. The hot mixture of gas and vapors entermg tower 1 through pipe 13 is partially cooled by coming in contact with the cool liquid sprayed over the surfaces of the filling 7. a cooling causes the vapors with the highest vaporizing temperature to condense out of the gas. The hea oil resulting from the condensation of t ese vapors accumulates on the filling 7 and runs down and collects in a reservoir 19 at the base of tower 1.

It is the important feature of my invention that the amount of cooling fluid sprayed over the filling 7 in tower 1 is limited and also that this cooling fluid is more volatile than the hea oil being condensed out in this tower. e result is that the passage of the gas upwards through the filling evaporates this cooling fluid. The amount of this cooling fluid is so limited that it is entirely evaporated into the gas by the time the cooling fluid drips down to the bottom of the filling 7. The reservoir 19 at the bottom of tower 1 is fitted with a steam coil 20 with which the accumulated heavy oil can be heated so that if any of the cooling fluid of this tower should drip down into the reservoir with the heavy oil, it can be vaporized again and sent forward with the gas.

Before being sprayed onto the filling in tower 1, the cooling fluid from pipe 10 is passed through a cooler, which consists of pipe coils, 21, which are kept moistened on the outside with water, over which a current of air is passed. This cooling water is supplied by sprays 22, fed from a cold water supply pipe, 23. Only just enough cooling water is used to moisten the cooling pipes, none being allowed to' drip off. As this water on the cooler pipes evaporates into the air, the absorption from the cooling fluid of the heat of evaporation of-this moistening water, cools the cooling fluid a considerable degree below the temperature of the available cooling water.

In a similar way the heat absorbed from the as in tower 1 by the evaporation of the cooling fluid from pipe 10, is many times as much heat as would be absorbed by passage of an equal amount of cooling fluid without evaporation.

When a mixture of vapors is cooled, some of each of the vapors condense. The amount of each that condenses is proportional to the relative changes in vapor pressures of each over the temperature range of the cooling.

A greater proportion of the vapors with highboiling temperatures condense and a less proportion of the vapors with low boiling temperatures. The resulting liquid is richer in the high boiling oint fractions than the original vapor. I this enriched liquid is again evaporated and condensed, the resulting liquid is further enriched in the high boiling point fraction. By repetition of such condensation and re-evaporation, the high boilin point fraction can be made as pure as is industrially desired.

The condenser of my invention operates in this fractionating way. The heavy oils which condense at the to of the filling 7 in tower 1, carry down wit them a considerable proportion of lighter oils. As this mixture of oils flows down over the filling it comes in contact with hotter and hotter gas, which eventually re-evaporates a part of the mixture of oil. This re-evaporated part is richer in the lighter oilsand poorer 1n the heavy oils, than the initial oil mixture at the top of thefilling. The remainder 'which is not re-evaporated is richer in the heavy oils. As thecondensed oil goes down through the filling this action is repeated untiltheheavy oil leaves ,the bottom of the filling in as pure :1 state as is desired. If through poor adjustment of the flow of gas and cooling fluid, some of the lighter oil is carried down into the reservoir 19 at the bottom of tower 1, the oil accumulated in this reservoir 19can be heated by the steam coil 20, and this lighter oil vaporized out. From the top of the filling 7 in tower 1 the mixture of gas and vapors, stripped of its heavy oil, goes forward to tower 2 where a similar action takes out pure medium oil, which accumulates in the reservoir 24. This medium oil in place of being heated by steam is heated by a coil 25 throu h which is passed the hot freshly condensed heavy oil from reservoir 19 of tower 1. From thiscoil 25 the heavy oil passes by the pipe 25 to the heavy oil storage tank 26.

From the top of the filling 8 in tower 2, the mixture of gas and .remaining vapor,

stripped of its heavy and medium oils, goes medium oil storage tank 29. From reser-" voir 27, the light oil goes to storage tank 30.

It is medium oil from storage tank 29, which is cooled in cooler coils 21, and through pipe '10 is sprayed over filling 7 in tower 1, to give the initial cooling to the incoming mixture of as and vapors. This medium coolin oil is aken from storage tank 29 througi pipe 31 by means of pump 32 and pipe 33.

In the same way, the light oil from storage tank 30 is carried by pipe 34 to pump 35 and by pipe 36 to a cooler coil 37, in which it is cooled by sprays 38 of cooling water and goes through pipe 11 to moisten the filling 8 in tower 2.

In towers 2 and 3, as well as in tower l,

the amount of cooling fluid is limitedto'the amount which the permanent gascan evaporate and carry forward. Itshould benoted that the carrying ability of a volume of gas for each of these cooling fluids is determined for each fluid by the temperature of the gas and is substantially independent of what other fluids orvapors the gas: is carrying at the same time.

dium oils of the original gas mixture.

The action of this evaporative condenser of my invention, may be considered from a thermal point of view as one of substitution. In tower 1, medium oil is substituted for the heavy oil as a carrier of the part of the heat of the original gas and vapor mixture represented by the sensible and latent heat of the heavy oil. In tower 2, light oil is substituted for the medium oil, both that contained in the gas originally and that added by evaporation in tower 1, as a carrier of the part of the heat of the original gas and vapor mixture, represented by the sensible and latent heat of both the heavy and mIen tower 3 in a similar way water is substituted as a carrier of all the heat representedby the sensible and latent heat of the heavy, medium and light oils of the gas mixture and by the heat equivalent of the lowering of temperature of the incondensable gas.

In the normal operation of this evaporative condenser, no heat is added to the system, all the functioning heat being carried in by the arriving mixture of permanent gas and vapors. The action throughout is one of the progressive removal of heat in such manher, that the fractions condensed shall be sharply free from the other fractions of higher and lower boiling points. To this end, the towers and all connecting pipings are thoroughly insulated against heat losses, so that the available heat can be removed at such points and in such a way as to most effectively fractionate the products.

It is common in fractionating stills and columns to return part or all of the condensate contained in the original vapor from a subsequent condenser. The arrangement of the apparatus of my invention is such that it is possible to return many times this amount of condensate. The amount that can be returned for cooling and fractionatl'ng is only limited by the ability of the gas, accompanying the vapor, to carry forward the added vapor, under the partial pressure conditions of the existing temperature.

I desire it to be understood that I am not restricted to the particular construction, combination and arrangement of parts as herein described and illustrated, but I reserve the right to make all such changes as fall within the scope of the following claim.

What is claimed is:

An apparatus for condensing vapor from a mixture of permanent gas and hydrocarbon vapor comprising a series of towers having filling therein and reservoirs in the bases thereof for the liquid condensate, means to heat the condensate in the initial tower, means for circulating the hot condensate from the initial tower through the condensate in the second tower in the series, and similar means for circulating the condensate from all of the subsequent towers through the condensate of the next following towers, the condensates of previous towers being circulated out of contact with the condensates in the subsequent towers,-

spray pipes in the towers above the fillings, means for circulating the condensate of a subsequent tower to the spray pipe of the tower immediately prior, and means for cooling the condensate on its way to the spray pipe, and means for supplying water to the spray pipe of the last tower in the serles.

FREDERICK T. SNYDER.

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