An Improved Process for Separating the Gas from the Lubricating Liquid Used in the Compression Pump of Refrigerating Machines.
Year: 1887

page_text: COMPLETE SPECIFICATION.
An Improved Process for Separating the Gas from the Lubricating
Liquid Used in the Compression Pump of Refrigerating
Machines.
I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention which bas
been communicated to me from abroad by "The De La Vergne Refrigerating Machine
Company" (Incorporated) of No. 157 Bank Street in the City and State of New York,
United States of America, and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :—
In all of the known processes in which a lubricating liquid is employed the gas is
compressed in some kind of a pump to which liquid is supplied and this liquid after
being discharged from the pump in connection with the compressed gas is separated
mechanically from the gas or the liquefied gas and returned to the pump. In some of
these processes the oil is cooled after leaving the pump and before it is returned to it;
in others the oil is not cooled prior to its return to the pump. In some of these
processes the oil is kept under substantially the pressure at which it left the pump
until it returns to it; in others the oil is relieved to a greater or less extent from
pressure after leaving and before it is returned to the pump. In some of these
processes the oil is injected into the pump after the suction stroke thereof is completed;
in others during the suction stroke; in still others during the compression stroke and
in some instances during both the compression and the suction stroke. The oil is also
sometimes admitted or forced into the compression pump in measured quantities, and
sometimes through a simple pipe controlled by a cock. In some of these processes
the oil is cooled in the presence of gas; in others after it has been separated
mechanically from the gas.
My improvement is applicable to any of these processes and requires in order to
work it out fully first, a compressing pump; second, a condenser; third, an
expansion coil or its equivalent; fourth, a separator or separating tank or tanks for
separating oil from gas mechanically; fifth, necessary connections of these parts so
that expanded gas may be returned to the compressing pump and that oil discharged
from the pump may be returned thereto, all these parts being such as are well known
and usually employed in refrigerating apparatus. In addition to these parts or
subdivisions of a complete apparatus there is needed for carrying out my improvement
some means such as a jacketed kettle, or steam coil, or their substitutes or equivalents
for heating the oil after has been wholly or partially mechanically separated from
the gas and during its progress from the discharge valves of the compressing pump
and before it returns or is returned to the pump again and some proper connection
from the cavity in which the oil is heated to the pressure side of the apparatus.
The drawings illustrate the arrangement of the various parts of a well known

page_text: refrigerating machine or system and also a coil for heating oil after it has been wholly
or partially mechanically separated from the gas. In these drawings A represents the
compressing pump; B a tank for mechanically separating the oil from the compressed
gas, the oil settling to the bottom, and the gas rising to the top from whence it flows
through a pipe to a condenser C, and after being liquefied by condensation, it passes to
the liquid ammonia tank D, from which it is usually passed through a wire drawing-
cock to the expansion coil E, where it expands and performs its refrigerating work,
and returns to the compressing pump to be again compressed and expanded and so on
indefinitely. In the lower portion of the separating tank B, the appliance for heating
the oil and driving the gas therefrom is interposed, as for example the coil & which
may take steam from any suitable source of supply. The oil after being heated as
before stated, passes from the tank B to the oil cooling coil F, and when cooled flows
into the oil supply tank G, from whence it flows or is taken back to the compressing
pump and after performing its lubricating and sealing functions, is discharged along
with the compressed gas and again separated and returned as explained.
I use the word "oil" in this description and specification as including and defining
any of the liquids and their equivalents now employed in refrigerating processes for
the purpose of filling up clearances in compression pumps and preventing leakage of
pistons, piston rods, valves, etc., and the word "gas" as including and defining all the
various kinds of gas applicable for refrigerating purposes by compressing them and
then permitting them to expand.
"
In such processes the oil takes up in the pump more or less of the gas which is
being compressed and retains more or less of such gas after the oil has been expelled
or discharged from the pump, if the oil during its progress from the discharge-valves
of the pump until its return thereto has the pressure upon it relieved the theory is
that some gas then escapes from the oil, said gas escaping not to waste, but into the
suction or expansion side of the apparatus whence the gas is returned to the compressing
pump. If the oil be kept substantially under the pressure at which it left the com-
pressing pump and until its return thereto the theory is that the gas in the oil escapes
in the pump, when the pressure in the pump is less than that of the entering oil, and
that this gas thus escaping cools the pump, and also enables it to deliver at each stroke
more gas than it would if the oil contained no gas at all, or less gas than was due to
the pressure under which the oil was discharged from the pump. In both these ways
of working refrigerating apparatus, however, the gas which escapes from the oil,
either in the pump itself or into the suction or expansion side of the apparatus must
be recompressed, because in all known forms of refrigerating apparatus the gas
circulates throughout the whole apparatus and none of it is permitted to escape into the
outer air to waste.
Now it is a well known fact that the oil will other things being equal, hold more
gas at a high pressure than at a low one, and that it will, other things being equal,
hold more gas at a low temperature than a high one, that is, if oil containing absorbed
or mechanically mixed therein a certain quantity of gas be heated then the oil will
part with a quantity, more or less, of this gas even if the pressure be not reduced.
It is further known to those using the well known processes, that the mechanical
separation of the oil from the gas in separating tanks or their substitutes for the
purpose is by no means perfect and that the oil usually contains gas mechanically
mixed therewith. A consideration of these facts has led me to this invention, and it
consists in an addition to the usual processes whereby the oil after being wholly or
partially mechanically separated from the gas as usual, is heated so that some of the
absorbed and contained gas is to a greater or less extent expelled therefrom and
delivered into the pressure side of the apparatus. This heating takes place after the
oil has been ejected from the pump and prior to its return thereto, and after the oil
has been wholly or partially mechanically separated as usual from the compressed gas
and I prefer to separate the oil mechanically from the gas soon after they leave the
pump and before the gas is cooled in the condenser.
I also prefer to cool the oil after it has been thus exposed to heat and before it is
returned to the pump.

page_text: If there be in the apparatus as a whole, as is usual, a separating tank or its
equivalent into which the whole charge of gas and oil from the pump is discharged
and to the bottom of which the oil drops I place in the bottom of such tank a coil
heated by steam, the heat from this coil will expel some of the gas from the oil, and
this gas will go off with the gas discharged from the pump, into the pressure side of
the apparatus and be cooled in the condenser, adding to the whole quantity of
compressed gas that additional quantity which is driven off from the oil by heating
the oil. The oil after this heating and before it returns to the pump is by preference
cooled by water in the usual apparatus or in other suitable known manner or I may
heat the oil in a coil, pipe or kettle, after it leaves the separating tank provided the
cavity in which it is heated is not open to the air and is in some way connected to the
pressure side of the apparatus so that the gas separated by heat will be introduced
into the pressure side of the apparatus, the gas thus driven from the oil being subse-
quently cooled either in the usual or in a separate condenser. It will be apparent that
this process economizes all the gas which is separated by heat, sending it to the
pressure side of the apparatus so that it may be used while expanding for refrigerating
purposes; it is true that when this oil returns to the pump it must again be charged
with gas requiring some power to produce this charging, but as this gas so charged is
again wholly or partially driven off by the subsequent heating of the oil my process
appears to me to work so far as effect is concerned much to the same advantage that
would follow from the use of an oil which would absorb no gas. Such an oil is not
yet known but my process is designed for securing advantages similar to those which
would result from the use of such oil if it were known.
The oil may be heated to drive off the gas after the oil has been cooled in the
presence of gas and separated mechanically therefrom, provided the gas thus driven off
is conducted to the pressure side of the apparatus, but this is an inferior way of
working my process.
I have throughout this description used the word heating without specifying any
certain temperature because different degrees of heat will be required for different
oils, because the degree of heat will be in some measure dependent upon the
temperature at which the oil leaves the compressing pump; and also upon the
boiling point of the particular oil used, but I can define generally the degree
of heat to be applied to the oil by stating that it must be greater than that at
which the oil leaves the compressing pump and less than that at which the oil
boils.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
First The improvement in the refrigerating process herein described which
consists in heating the oil after it has been expelled from the pump and conducting the
gas driven off by such heating into the pressure side of the apparatus ; said heating
being performed after the oil has been partially or wholly separated mechanically from
the gas and before the oil is returned to the pump.
Second I claim the improvement in refrigerating process herein described which
consists in heating the oil after its expulsion from the pump and subsequent to
mechanical separation from the gas, and the cooling of such oil after it has been heated,
the gas driven off by the heating and prior to the cooling of the oil being conducted
to the pressure side of the apparatus.
tabo 1007