SYSTEME DE GAZEIFICATION A FAIBLE CONSOMMATION D'ENERGIE

LOW ENERGY GAS TRANSFER SYSTEM

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
Liquid is collected and gasified within the same pressure sealed
chamber from which it is displaced. The liquid is gasified toward saturation
under a high pressure for a limited time by recirculation of the gas through
the chamber. Flow control valves establish a closed circuit through which
recirculation occurs while the chamber is maintained pressurized as well as
to effect displacement of gas saturated liquid from the chamber during spaced
intervals of time while the chamber is depressurized.

Revendications

The embodiments of the invention, in which an exclusive
property or privilege is claimed, are defined as follows:
1. In combination with a conduit through which a fluent material
is conducted under a first pressure, fluid transfer apparatus including
pressure sealed means enclosing a chamber within which said fluent material
is collected, flow control means connecting the pressure sealed means to
the conduit for displacing the collected fluent material from the chamber
under said first pressure during spaced intervals of time, pump means for
inducing flow of fluid under a second pressure different from the first
pressure, recirculating flow means connecting the pump means to the
pressure sealed means for directing said flow induced by the pump means
through the chamber between said spaced intervals of time, and flow
exchange means connected to the recirculating flow means for replacing
any free fluid in the chamber with fluent material before said displacement
of the collected fluent material under the first pressure.
2. The apparatus as defined in claim 1 wherein said flow
exchange means includes a surge tank within which the free fluid collects,
valve means interconnecting the surge tank and the chamber for conducting
the free fluid and the fluent material in opposite directions until the
free fluid is completely replaced within the chamber, and sensor means
connected to the pressure sealed means for detecting the absence of the
free fluid in the chamber.

3. The combination of claim 1 including a source of compressible
fluid, said fluid transfer apparatus being operative to transfer said
compressible fluid to the fluent material, said collected fluent material
in the chamber being saturated with said compressible fluid under the
second pressure, and completely filling the chamber before displacement
therefrom under said first pressure, said recirculating flow means
comprising a closed circuit connecting the pump means to the chamber,
and means for limiting recirculation flow of the fluid to periods between
said spaced intervals of time.
4. The combination of claim 3 wherein said flow exchange means
includes a surge tank interconnected between said source of fluid and the
pump means and control valve means interconnecting said chamber with
the surge tank and the pump means for transfer of excess fluid from the
chamber to and replacement thereof with the fluent material from the surge
tank.
5. The combination of claim 4 wherein said recirculation
limiting means includes sensing means connected to said chamber for
initiating operation of the pump means in response to completion of
said transfer of excess fluid from the chamber to the surge tank,and
timer means for terminating operation of the pump means prior to said
displacement of the saturated fluent material from the chamber to enable
non-forced flow exchange between the surge tank and the chamber device
during which the excess fluid is transferred.

6. The combination of claim 5 wherein the pressure sealed
means includes a second chamber connected to the flow control means
and the closed circuit for recirculation of fluid therethrough
simultaneously with said displacement of saturated fluid material
from the first mentioned chamber and displacement of saturated fluent
material therefrom simultaneously with said recirculation of fluid
through the first mentioned chamber.
7. The combination of claim 3 wherein said flow control means
includes one-way valve means for conducting the fluent material from the
conduit into the chamber device when depressurized, and selectively con-
trolled outlet means for conducting the saturated fluent material from the
chamber device causing depressurization thereof.
8. In combination with a conduit conducting liquid under a
relatively low pressure, apparatus including pressure sealed means
enclosing a chamber within which the transfer of gas relative to the
liquid is effected, flow control means connected to the pressure sealed
means for connecting the chamber to the conduit to displace the liquid
therefrom under said low pressure, pump means inducing flow of transferred
gas alone relative to said chamber under a relatively high pressure,
closed circuit means connecting the pump means to the pressure sealed
means for recirculating the gas through the chamber under said relatively
high pressure, operational control means connected to the closed circuit
means and the flow control means for alternately effecting said transfer
of the gas under the high pressure within the chamber and displacement of
the liquid under the low pressure from the chamber, and means for limiting
operation of the pump means to discontinue recirculation of the gas for a
short interval before displacement of the liquid from the chamber occurs.

9. A method of gasifying a liquid flowing under a relatively
low pressure with a gas under a relatively high pressure, including the
steps of: collecting a predetermined quantity of said liquid within a
pressure sealed zone; injecting said gas into the same zone for absorption
by the liquid; recirculating said gas through said zone under said high
pressure for a limited period of time; maintaining said zone pressurized
for a short interval of time upon termination of said recirculation of the
gas; replacing any free gas in said zone with liquid during said short
interval of time; depressurizing the zone; and displacing the gasified
liquid from said depressurized zone under the low pressure of the liquid.
10. The method of claim 9 wherein the step of replacing the
free gas includes: conducting liquid displaced by the gas under the high
pressure from said zone into a surge chamber; and draining the liquid from
said surge chamber back into the zone during said short interval of
time.
11

Description

1~351~
This invention relates to the transfer of compressible fluid or
gas such as oxygen or hydrogen to a relatively incompressible fluent material
or liquid such as water or a cool slurry and is an improvement over the gas
transfer systems disclosed in my prior U.S. Pat. Nos. 3,926,588 and 4,087,262.
According to my prior U.S. Pat. ~o. 3,926,588, gas is injected
into a liquid within a gas transfer device and the gasified liquid is col-
lected within a separate plug-flow chamber by recirculation between the
chamber and the gas transfer device until the liquid is saturated. Recir-
culation occurs under a relatively high pressure for a limited period of time
through a closed loop. The saturated liquid collected within the plug-flow
chamber is then displaced therefrom by the inflow of the liquid under a low
pressure. Two chambers are utilized so that the high circulating pressure
may be maintained continuous even though it is only applied intermittently
to each individual chamber. In order to avoid effervescence, a diluent is
introduced into each chamber when depressurized according to my prior U.S.
Pat. No. 4,087,262.
In view of the use of a separate gas transfer device in association
with the plug-flow chambers as disclosed in my prior U.S. patents aforemen-
tioned, flow losses occur because of the necessary connecting conduits. Also,
considerable equipment cost is involved. It is therefore an important object
of the present invention to provide an improved gas transfer system which will
reduce the cost of equipment and fluid losses inherent in the systems dis-
closed in my aforementioned prior U.S. patents.
In accordance with the present invention, the same pressure
sealed chamber is utilized for injecting the gas, gasifying the liquid
toward saturation, and diluting if necessary the gasified liquid to
prevent effervescence. A separate and costly gasifier is thereby avoided
and energy requirements reduced. A more efficient system is also realized
because of the reduction in the length of piping and the accompanying
decrease in fluid losses.

~13S~8~
As in the case of the systems disclosed in my prior U.S. patents
aforementioned, the present invention may be practiced by use of two pres-
sure sealed chambers connected to a conduit through which a liquid flows
under a relatively low pressure, whereby a predetermined quantity of liquid
may be collected within each chamber and alternately displaced from each
chamber under the low pressure. Saturation of the liquid with gas is
effected in each chamber by recirculation of the gas during a limited
period of time under a high pressure. Since the transfer of the gas
occurs within the same chamber in accordance with the present invention, a
separate gasifier is avoided. Dilution of the æaturated liquid within the
same chamber in order to avoid effervescence is also effected. Toward
that end, each pressure sealed chamber is depressured by opening of a
selectively controlled outlet valve operative to effect displacement of
liquid from the chamber under the inflow of low pressure liquid. Upon
closing of the outlet valve, the chamber is pressurized and then connected
through other valving to a closed fluid circuit for flow recirculation
under the high pressure.
In order to effectively inject the gas into the liquid, a surge
tank is interconnected in the closed fluid circuit between the high pressure
circulating pump and the chamber. During the recirculation phase of each
cycle, some liquid is displaced by the pressurized gas into the surge tank.
The surge tank permits separation of free gas from the liquid for recirculation
of the free gas with additional gas from the source replenishing the gas
absorbed by the liquid in the chamber. The recirculation phase of the cycle is
terminated before the chamber is depressured in order to permit a non-forced
fluid exchange between the surge tank and the chamber whereby liquid in the
surge tank drains back into the chamber. As soon as all of the excess gas in
the chamber is withdrawn and replaced by exchange with
liquid, this condition is detected by a sensor and the chamber is
depressuriæed by opening of the outlet valve causing displacement of the

11351~
gasified liquid under the low liquid pressure. At the same time, the
closed, recirculation circuit is switched from the depressurized chamber
to the other chamber of the system which simultaneously undergoes a gasi-
fication phase under the high recirculating pressure. In response to
depressurization of each chamber to begin a low pressure displacement
phase of operation, a diluent is introduced into the chamber in order to
prevent effervescence.
Figure 1 is schematic fluid circuit diagram depicting the system of
the present invention.
Figure 2 is simplified electrical circuit diagram illustrating the
controls associated with the system illustrated in Figure 1.
Figure 3 is a graphical illustration of valve and pump operating
characteristics of the system.
Ref~rring now to the drawings in detail, Figure 1 illustrates
a gas transfer system generally denoted by reference numeral 10, which
is based upon the use of two vertically elongated chambers 12 and 14 en-
closing pressure sealed zones within which all operational phases of the
system occur including injection of gas from a source 16 into a collected
body of liquid 18, gasification of the liquid, and dilution of the gasified
liquid from a source of diluent 20. Liquid such as water may be gasified
with oxygen fronl source 16, for example, by the system of the present inven-
tion to which the liquid is introduced through an inlet conduit section 22
under a relatively low pressure. The gasified liquid is delivered by the
sy~tem to an outlet conduit section 24.
Liquid is conducted to each of the pressure sealed zones within
charnbers 12 and 14 and displaced therefrom by means of a flow control arrange-
ment including a pair of one-way check valves 26 and 28 respectively connect-
ing inlet conduit section 22 to the lower ends of each of the chambers 12 and
14. The upper ends of the chambers are respectively connected through lines
30 and 32 to the outlet conduit section 24 by rneans of a selectively

11351~3~
controlled outlet valve 34. In the position of the outlet valve 34 shown in
Figure 1, chamber 14 is connected to the outlet conduit section 24 and is
therefore depressurized so that the liquid 18 therein may be displaced by
an inflow of liquid through one-way check valve 28. Since outflow from
chamber 12 is then blocked by the outlet valve 34, chamber 12 will be pres-
surized and inflow through one-way check valve 26 will be blocked.
The source of pressurized gas 16 is connected to the system through
a closed fluid circuit generally referred to by reference numeral 36 which
includes a surge tank 38 and a high pressure recirculating pump 40. Also
associated with the closed circuit 36, is a fluid exchange valve 42 inter-
connecting the surge tank 38 with the pressure sealed chambers 12 and 14 and
a gas injection valve 44 innerconnecting the outlet of the pump 40 with the
pressure sealed chamber 12 and 14 adjacent their lower ends. Diluent from
source 20 is conducted to each of the chambers 12 and 14 through one-way
check valves 46 and 48 and is injected into the chambers through distributed
inlet ports 50 as disclosed in my prior U.S. Pat. No. 4,087,262.
In the position of the gas injection valve 44 shown in Figure 1,
gas under pressure is supplied by pump 40 from the surge tank 38 to chamber
12 through pump outlet line 52 in order to effect gasification of the liquid
in chamber 12. The other outlet line 54 from the gas injection valve 44 to
chamber 14, is blocked so that recirculation flow is confined to chamber 12,
which is then pressurized because of the blockage of outlet line 30 by the
outlet valve 34. Fluid exchange between chamber 12 or 14 and the surge tank
38 is controlled by valve 42. In the position of valve 42 shown in Figure 1,
fluid exchange occurs between the chamber 12 and the surge tank while fluid
exchange between the chamber 14 and the surge a tank is blocked. Accordingly,
liquid displaced from chamber 12 by the pressure of the gas being injected
may enter the surge tank within which free gas separates from the liquid bub-
bling into the gas space 56. Gas is withdrawn from the gas space of the surge
tank by the pump 40 through line 58 while gas to replenish the gas absorbed

~13518J.
by the liquid is supplied from the source 16 through line 60. During the
gasification phase of operation, gas bubbles will accumulate in chamber 12.
This excess gas is exchanged with the liquid stored in the surge tank at
the end of the gasification phase. Termination of the gasification cycle is
thereby detected by gas sensor 64 or 66 connected to the upper ends of the
chambers 12 and 14. The sensors may thereby control operation of the system
in order to obtain the desired degree of liquid gasification or gas saturation.
As shown by way of example in Figure 2, a simplified control
arrangement including the sensors 64 and 66 is operative in effecting simul-
taneous actuation of the valves 34, 42 and 44 by means of solenoid actuators
68. The valves are accordingly actuated by closing of a sensor switch 70
when sensor 64 detects the end of a gasification phase with respect to
chamber 12. At the same time, operation of pump 40 is initiated through a
timer control circuit 72 energizing pump motor 74. Through the timer con-
trol circuit 72, the pump 40 is operated for a limited period of time
sufficient to effect gas saturation of the liquid in the chamber to which
it i~ connected by valve 44. Operation of the pump is terminated by
de-enerization of the pump motor 74 before the end of a gasification phase
in order to permit non-forced fluid exchange between the surge tank and
the chamber through valve 42 for a short interval of time. During this
short interval, liquid drains back into the chamber from the surge tank to
displace and replace the excess gas.
The relationship between pump operation and valve actuation is
graphically depicted in Figure 3 which shows energization of the valve
actuator~ 68 during one-half of each cycle as depicted by curve 76.
During each half cycle, the pump motor is also energized as depicted by
curve 78 in Figure 3. The pump motor is, however, energized for less
than the duration of each half cycle so as to establish a short exchange
interval 80 as depicted in Figure 3 during which the non-forced fluid
exchange occurs between the surge tank and the chamber to which it is

i~351~
connected. Each half cycle is begun by the simultaneously shifting of
all of the valves 34, 42 and 44 so as to switch the connections between
the chambers 12 and 14 and the surge tank 38 and pump 40.
Summarizing operation of the system, in the position of the
valves shown in Figure 1, liquid is conducted through check valve 28 to
displace previously gasified liquid from chamber 14, through valve 34
to outlet conduit 24. During this phase of operation, liquid is simultane-
ously being gasified within chamber 12 by the supply of gas from pump 40
under a relatively high pressure through line 52. Chamber 12 is then in
fluid communication with the surge tank through valve 42 so that some of
the liquid wiil be displaced by gas pressure into the surge tank. Before
the end of the half cycle, determined by the timer con~rol 72, operation
of the pump 40 i8 discontinued so that liquid in the surge tank 38 may
drain back into the chamber 12 and excess gas in chamber 12 may rise and
bubble through any liquid remaining in the surge tank. As soon as the
excess gas has been withdrawn from the chamber 12, this condition is de-
tected by the sensor 64 to begin a new half cycle. Sensor 64 thus closes
sensor switch 70, as shown by way of example in Figure 2, in order to
energize the valve actuators causing simultaneous shift of the valves 34
42 and 44 to their other operative positions. Chamber 12 will then be
depressurized by connection through line 30 and valve 34 to the outlet
conduit section 24 resulting in displacement of the gasified liquid
therefrom by the inflow of liquid through one-way check valve 26. At the
same time, the pump motor 74 is energized through timer control circuit 72
80 that operation of the pump 40 is resumed in order to begin a new gasifi-
cation phase with respect to the chamber 14. Gasification occurs within
chamber 14 in the same manner as hereinbefore described with respect to
chamber 12. Operation of the pump 40 is discontinued under control of the
timer circuit 72 as aforementioned to permit fluid exchange between chamber
14 and surge tank 38 until the end of the half cycle is detected by sensor

113518~
66. Sensor 66 will then deenergize the valve actuators by opening sensor
switch 76 in order to initiate a new operational cycle by return of all of
the valves to the positions shown in Figure 1. The check valves 46 and 48
respond to depressurization of associated chambers 12 and 14 in order to
conduct an inflow of diluent from source 20 for preventing effervescence
if necessary.