Method of and Apparatus for Increasing the Efficiency of Evaporative Surface Condensers.
Year: 1894

page_text: Date of Application, 11th Aug., 1894-Accepted, 29th Sept., 1894
CUMI LEIE DI ECIP
CATION.
Method of and Apparatus for Increasing the Efficiency of Evaporative
Surface Condensers.
I, EDUARD THEISEN, of No. 4 Kronprinzen Strasse, Baden-Baden, in the
Empire of Germany, Engineer, do hereby declare the nature of this invention,
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
In surface condensers working with cooling by evaporation where the actual
cooling medium is the atmospheric air, the cooling water only serving by its
evaporation to transfer to the air the heat of the steam which is set free on
condensation, there is, in consequence of the comparatively high condensing
temperature of about 60° C. when compared with the vacuum obtained, a
considerable volume of uncondensed gases contained in the condenser.
In addition, such air as leaks in owing to want of tightness of the cylinder,
stuffing boxes, pipe connections &c. is the more detrimental, the higher the
temperature of the condenser is.
This condition is especially to be observed when for the purpose of economy. in
first outlay and in subsequent working means of cooling the water are omitted, and
the cooling water is used over and over again with an addition of fresh cooling
water to make good that lost by evaporation this quantity being nearly equal to
that of the water of condensation from the steam.
Now the volume of uncondensed gases which have to be withdrawn from the
condenser determines the size and working of the air pump, and on this ground it
is desirable that the uncondensed gases should have as low a temperature as
possible when entering the air pump, as the lower the temperature is, the smaller
will be the volume and a better vacuum will be easily gained.
On the other hand, the rapidity of evaporation of the evaporative condensing
water and consequently the intensity of the condensation will depend mainly upon
the difference between the temperature of such water and that of the atmospheric
air passing in contact therewith. The greater this difference is the more rapid will
be the evaporation, or in other words the smaller can be the amount of surface of
the condenser for performing a certain duty.
As now the temperature of the atmospheric air is practically a determined
factor, the said difference of temperature will be increased when the temperature
of the cooling water is kept as high as possible, and nearly equal to that of the
steam entering the condenser.
Now according to my present invention I prevent such detrimental cooling effect
and at the same time reduce the volume of the uncondensed gases before they enter
the air pump, by employing the aforesaid supplemental supply of cold condensing
water to cool the uncondensed gases withdrawn from the evaporative surface con-
denser and consequently reduce their volume, before they enter the air pump, the
supplemental condensing water being thereby correspondingly raised in temperature
before it is added to the main body of evaporative condensing water of the
condenser. By this means it will be seen that the double beneficial effect is
obtained of, on the one hand, considerably, reducing the size and work of the air
pump for performing a certain amount of duty, and on the other hand, of utilising
firstly the low temperature of the supplemental cooling water and secondly the
quantity of this water for cooling by evaporation.
On the accompanying drawing is shewn by way of example a diagrammatic
section of an apparatus by which the above described method of operating can be
carried out. The exhaust steam from the steam engine or other apparatus is

page_text: condensed on the inner surface of the evaporative surface condenser R in which
the steam enters at A.
The water of condensation runs down the tubes into the bottom compartment
and is drawn off at Wc. The outer surfaces of the condenser R receive a supply
of evaporative condensing water from the supply We and after flowing down the
outer surfaces of the tubes this water is drawn off at We, as indicated by the
arrows.
Atmospheric air is made to impinge upon the film of water flowing down
the tubes R a portion of which is consequently continuously evaporated and
carried off thereby. This loss is continuously replaced by an additional supply of
condensing water which enters at Wa, after having been made to pass through a
casing S in contact with the refrigerating worm S through which the uncondensed
gases are drawn off from the condenser R by the air pump (not shewn) connected
to S at L, such gases being thus cooled down to a corresponding extent before
entering the air pump, while the additional condensing water entering at Wa is
warmed to a corresponding extent before mixing with the main supply of condensing
water.
It will be evident that the apparatus for carrying out my above described
method of operating can be variously constructed without departing from the
nature of my invention; the accompanying diagram is only intended as an example
of the mode of carrying the invention into practice.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In evaporative surface condensers, the method of cooling the uncondensed
gases drawn off from the condenser before they enter the air pump, by means of a
cold water supply which is, after having its temperature raised by this means, then
added to the evaporative condensing water of the condenser for making good the
quantity thereof lost by evaporation, substantially as and for the purposes
described.
2. The combination with an evaporative surface condenser, of a supplemental
surface condenser through which the uncondensed gases from the evaporative
surface condenser are made to pass on their way to an air pump, the outer casing
of such surface condenser being made to communicate at one end with a supply of
cold water and at the other end with the chamber of the evaporative surface
condenser containing the evaporative condensing water, substantially as and for
the purposes described.
Dated this 11th day of August 1894.
ABEL & IMRAY,
Agents for the Applicant.