U.S. patent number 3,672,182 [Application Number 05/049,859] was granted by the patent office on 1972-06-27 for water cooling method and apparatus employing liquid nitrogen.
This patent grant is currently assigned to Air Products and Chemicals, Inc.. Invention is credited to Keith A. Miller, William F. Stowasser.
United States Patent |
3,672,182 |
Stowasser , et al. |
June 27, 1972 |
WATER COOLING METHOD AND APPARATUS EMPLOYING LIQUID NITROGEN
Abstract
Water is cooled by the direct injection thereinto of liquid
nitrogen. Preferably, heat is applied in the vicinity of the
injection zone and preferably the injection of the liquid nitrogen
is intermittent with inert gas being injected when liquid nitrogen
is not injected. The application of the heat and the injection of
the gas eliminates the tendency of the injector to be plugged by
ice formation.
Inventors: |
Stowasser; William F.
(Allentown, PA), Miller; Keith A. (Allentown, PA) |
Assignee: |
Air Products and Chemicals,
Inc. (Allentown, PA)
|
Family
ID: |
21962128 |
Appl.
No.: |
05/049,859 |
Filed: |
June 25, 1970 |
Current U.S.
Class: |
62/98; 62/121;
62/201; 62/389; 62/70; 62/157; 62/306 |
Current CPC
Class: |
F25D
3/10 (20130101); F28C 3/00 (20130101); F28C
3/06 (20130101); F25B 47/006 (20130101); B28C
7/0038 (20130101) |
Current International
Class: |
F25D
3/10 (20060101); B28C 7/00 (20060101); F25B
47/00 (20060101); F28C 3/00 (20060101); F28C
3/06 (20060101); F25d 017/02 () |
Field of
Search: |
;62/48,55,66,70,98,157,121,171,201,306,314,340,386,389,396,514 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Perlin; Meyer
Claims
What is claimed is:
1. A system for cooling water by the direct injection thereinto of
liquid nitrogen, said system comprising a horizontally oriented
water reservoir having extending thereinto a plurality of liquid
nitrogen injector nozzles, each of said nozzles being equipped
adjacent its downstream end with a heating element the heat
emanating from said heating element functioning to prohibit its
nozzle from being plugged with ice.
2. A system as recited in claim 1 which additionally comprises a
temperature control and a temperature sensing probe, said
temperature sensing probe, when water in said tank is at a
temperature above the temperature desired, acting to generate a
signal which is received by the temperature control which in
response initiates and maintains flow of liquid nitrogen through
said nozzles into said tank; said temperature sensing probe, when
the water in said tank reaches the desired temperature, generating
a signal which is received by said temperature control which in
response operates to discontinue the flow of liquid nitrogen.
3. A system as recited in claim 1 wherein each of said nozzles has
an outlet only at its downstream end.
4. A system as recited in claim 1 wherein each of said liquid
nitrogen injector nozzles is vertically oriented.
5. A system for cooling water by the direct injection thereinto of
liquid nitrogen, said system comprising a horizontally oriented
water reservoir having extending thereinto a plurality of liquid
nitrogen injector nozzles, each of said nozzles having an outlet
only at its downstream end and being equipped adjacent its
downstream end with a heating element, the heat emanating from said
heating element functioning to prohibit its nozzle from being
plugged with ice; each of said heat elements being joined to
conductors which lead to a source of electric power.
6. A system as recited in claim 5 wherein the path that a heating
element follows consists essentially of three U-shaped
configurations in sequence with the first and third U-shaped
configuration being essentially parallel and with the second
U-shaped configuration being formed by the joining of the
inner-vertical legs of each of said first and third U-shaped
configurations, each of said vertical legs extending in a direction
parallel to the longitudinal axis of the nozzle associated with the
heating element, said path being adjacent the outer surface of said
nozzle except in the vicinity of said transition joints wherein
said path diverges from said nozzle to join said transition
joints.
7. A system as recited in claim 6 wherein the first and third
U-shaped configurations have the upper surface of their bases lying
in the same horizontal plane as the downstream end of said
nozzle.
8. A system as recited in claim 5 wherein a portion of each nozzle
which is not in contact with a heating element is covered by
insulation around which said conductors are spiralled.
9. A system for cooling water by the direct injection thereinto of
liquid nitrogen, said system comprising a horizontally oriented
water reservoir having extending thereinto a plurality of liquid
nitrogen injector nozzles, each of said nozzles being equipped
adjacent its downstream end with a heating element, the heat
emanating from said heat element functioning to prohibit its nozzle
from being plugged with ice; said system additionally comprising a
timer which acts to operate said heating element according to a
preset time schedule.
10. A system for cooling water by the direct injection thereinto of
liquid nitrogen, said system comprising a horizontally oriented
water reservoir having extending thereinto a plurality of liquid
nitrogen injector nozzles, each of said nozzles being equipped
adjacent its downstream end with a heating element, the heat
emanating from said heating element functioning to prohibit its
nozzle from being plugged with ice; said system additionally
comprising a temperature control and a temperature sensing probe,
said temperature sensing probe, when water in said tank is at a
temperature above the temperature desired, acting to generate a
signal which is received by the temperature control which in
response initiates and maintains flow of liquid nitrogen through
said nozzles into said tank, and when the water in said tank
reaches the desired temperature, generating a signal which is
received by said temperature control which in response operates to
discontinue the flow of liquid nitrogen; said system additionally
comprising a source of pressurized inert gas, said temperature
control acting to initiate inert gas flow from said source through
said nozzle when liquid nitrogen flow is discontinued, said
temperature control acting to discontinue said inert gas flow when
said liquid nitrogen flow is initiated and maintained.
11. A system for cooling water by the direct injection thereinto of
liquid nitrogen, said system comprising a horizontally oriented
water reservoir having extending thereinto a plurality of liquid
nitrogen injector nozzles, each of said nozzles having an outlet
only at its downstream end and being equipped adjacent its
downstream end with a heating element, the heat emanating from said
heating element functioning to prohibit its nozzle from being
plugged with ice; each of said heating elements spiralling around
its associated nozzle.
12. A method for cooling water to a temperature below ambient
temperature but above the freezing point of the water, said method
comprising the steps of (a) injecting into the water sufficient
liquid nitrogen to achieve said cooling as a result of said liquid
nitrogen vaporizing in said water and thereby abstracting from said
water an amount of heat substantially equal to its heat of
vaporization plus the sensible heat required to raise the
temperature of the resulting nitrogen vapor to the temperature of
the water and (b) preventing plugging of the injection route
occurring as a result of the water in the vicinity of the injection
route freezing by applying heat in the vicinity of the injection
route according to a preset time schedule.
13. In the production of concrete providing cold water by the
method of claim 12.
14. A method for cooling water to a temperature below ambient
temperature but above the freezing point of the water, said method
comprising the steps of (a) injecting into the water sufficient
liquid nitrogen to achieve said cooling as a result of said liquid
nitrogen vaporizing in said water and thereby abstracting from said
water an amount of heat substantially equal to its heat of
vaporization plus the sensible heat required to raise the
temperature of the resulting nitrogen vapor to the temperature of
the water and (b) preventing plugging of the injection route
occurring as a result of the water in the vicinity of the injection
route freezing by applying heat in the vicinity of the injection
route by the passage of electrical current through resistance.
15. A method as recited in claim 14 wherein said liquid nitrogen is
injected intermittently as it is needed for cooling, with an inert
gas being injected through the same injection route when liquid
nitrogen is not being injected.
16. A method as recited in claim 14 wherein said liquid nitrogen is
injected intermittently as it is needed for cooling, with dry air
being injected through the same injection route when liquid
nitrogen is not being injected.
17. A method for cooling water to a temperature below ambient
temperature but above the freezing point of the water, said method
comprising the steps if (a) injecting into the water sufficient
liquid nitrogen to achieve said cooling as a result of said liquid
nitrogen vaporizing in said water and thereby abstracting from said
water an amount of heat substantially equal to its heat of
vaporization plus the sensible heat required to raise the
temperature of the resulting nitrogen vapor to the temperature of
the water and (b) preventing plugging of the injection route
occurring as a result of the water in the vicinity of the injection
route freezing; said liquid nitrogen being injected intermittently
as it is needed for cooling with an inert gas being injected
through the same injection route when liquid nitrogen is not being
injected.
18. A method for cooling water to a temperature below ambient
temperature but above the freezing point of the water, said method
comprising the steps of (a) injecting into the water sufficient
liquid nitrogen to achieve said cooling as a result of said liquid
nitrogen vaporizing in said water and thereby abstracting from said
water an amount of heat substantially equal to its heat of
vaporization plus the sensible heat required to raise the
temperature of the resulting nitrogen vapor to the temperature of
the water and (b) preventing plugging of the injection route
occurring as a result of the water in the vicinity of the injection
route freezing both by the application of heat in the vicinity of
the injection route and by the injection of inert gas along the
injection route during those periods when liquid nitrogen is not
being injected along the injection route.
19. A method as recited in claim 18 wherein said inert gas is
nitrogen.
20. In the production of concrete providing cold water by a method
comprising the steps of (a) injecting into the water sufficient
liquid nitrogen to achieve said cooling as a result of said liquid
nitrogen vaporizing in said water and thereby abstracting from said
water an amount of heat substantially equal to its heat of
vaporization plus the sensible heat required to raise the
temperature of the resulting nitrogen vapor to the temperature of
the water and (b) preventing plugging of the injection route
occurring as a result of the water in the vicinity of the injection
route freezing; spent nitrogen gas from the vaporization of the
liquid nitrogen being utilized to cool the stone ingredient of the
concrete.
Description
BACKGROUND OF THE INVENTION
This invention is directed to a method and apparatus for cooling a
liquid by injecting thereinto a liquefied gas. This method and
apparatus are especially useful for providing cooled water which
can be utilized for example in the batch mixing of concrete.
In concrete preparation cooled water is ordinarily mixed with warm
cement, crushed stone and sand in a conventional mixer. If the
temperature of the concrete mix exceeds 80.degree.-85.degree. F.
prior to pouring the strength of the poured set concrete can be
reduced below acceptable levels. Especially during the warm summer
months the crushed stone and sand ingredients can be at a
temperature such that the temperature of the mix will exceed the
aforedescribed upper limit if the water ingredient is not
cooled.
One method controlling the temperature of the mix discharged from
the concrete mixer to within acceptable limits has been to add at
least a portion of the water to the mixer in the form of crushed
ice; because of ice processing and handling problems this is not an
especially good solution.
The present invention is directed to a method for overcoming such
handling problems by providing cold water as an ingredient by the
injection of liquefied gas into the water supply whereby it is
cooled to a predetermined temperature or to a temperature within
predetermined limits, said temperature being above the freezing
point of the water.
One problem involved with this type of cooling method is the
control of the cooling in local areas. In particular, the water in
the vicinity of the liquefied gas injector tends to freeze at the
discharge point plugging the injector so that further liquefied gas
cannot emit from it.
Another problem involved with this type of cooling method is
maintaining the injector tube clear and unclogged during those
periods when liquefied gas is not being injected, that is, during
those periods when the water supply into which the liquefied gas is
being injected has reached its prescribed temperature. In other
words, when liquefied gas is not being injected into the water, the
water in the supply being cooled can back up into the injector,
freezing therein and plugging the same.
Cooling methods are known in the prior art wherein liquefied gas
has been injected into a reservoir of liquid for cooling purposes.
For example, Dodkin U.S. Pat. No. 2,428,412 discloses the injection
of liquid carbon dioxide, liquid ethane, liquid propylene, or
liquid propane into methyl alcohol, ethylene glycol, kerosene or
acetone to cool the latter liquid for use for unblocking lenses.
Seefeldt U.S. Pat. No. 2,759,336, Hessen et al. U.S. Pat. No.
2,988,898 and Williamson U.S. Pat. No. 2,966,039 each discloses the
injection of liquefied carbon dioxide into an organic liquid to
cool the organic liquid. Each of these references discloses that
the carbon dioxide tends to solidify in the injection device
thereby blocking further injection. Each of these references offers
a solution to this problem. In Seefeldt blocking is eliminated by
the use of a nozzle including rotating vanes which extend
longitudinally through the nozzle. In Hessen et al. blocking is
eliminated by including within the nozzle a restricted opening
whereby solidified carbon dioxide is suspended in a vapor stream
during the course of injection. The Williamson patent is addressed
particularly to the problem of blockage by solidified carbon
dioxide due to intermittent injection of the liquid carbon dioxide.
The blockage is prohibited by expelling residual liquid carbon
dioxide from the injector on shut down by releasing a charge of
vaporized carbon dioxide which has been maintained under pressure
into the injector. No reference has been found, however, which
discloses the problem of blockage of the injector by the freezing
of the liquid which is being cooled, which is the problem in the
present case. Moreover, no reference has been found which discloses
the use of local heating to solve blockage due to liquefied gas
injection while said local heating is an important feature of one
of the embodiments herein. Moreover, no reference has been found
wherein vapor is continuously introduced through the injector
during periods when the liquefied gas is not being injected while
such continuous introduction is an important feature of the one of
the embodiments herein.
The present invention is directed to the use of a particular
liquefied gas for the purpose of cooling a liquid. This particular
liquefied gas is liquid nitrogen. Only one reference is known
wherein liquid nitrogen has been injected into another liquid to
cool the latter. That reference is Morrison U.S. Pat. No.
2,909,433. In Morrison, liquid nitrogen is injected during ice
cream preparation to expand and freeze the ingredients. Since
freezing of the treated liquid is an object in Morrison, no steps
are taken therein to negate freezing.
BRIEF DESCRIPTION OF THE DRAWINGS
In describing preferred embodiments of the invention reference is
made hereinafter to the accompanying drawings in which:
FIG. 1 is a schematic diagram in elevation of a preferred cooling
method and apparatus within the scope of the present invention;
FIG. 2 is an elevational view of a preferred injector nozzle
assembly for use within the scope of the present invention. The
injector nozzle assembly is shown bolted in place in a tank
wall;
FIG. 2A is a fragmentary view in elevation showing a slight
modification of the heating element of FIG. 2;
FIG. 3 is a cross-sectional view taken along lines 3--3 of FIG.
2;
FIGS. 4 and 5 are elevational views of other injector nozzle
assemblies useful within the scope of the present invention;
FIG. 6 is a plan view of the assembly depicted in FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
Referring to FIG. 1 there is shown a system and method for cooling
water by liquid nitrogen injection into the water wherein heat is
applied in the vicinity of the injection zone to maintain said zone
free from ice blockage. The system comprises a cylindrical tank 10
having a side wall 12 and end walls 14. The end walls 14 have outer
surfaces which are slightly convex. The longitudinal axis of
cylindrical tank 10 is horizontally oriented.
Communicating with cylindrical tank 10 is a water inlet line 16.
The upstream end of line 16 leads from a source of water, for
example, a well. Line 16 communicates with tank 12 in the lower
portion of one of its end walls 14. Also communicating with tank 10
is water outlet line 18. The downstream end of line 18 is at the
location where the cold water product is to be utilized. The line
18 communicates with tank 10 at the lower portion of the wall 14
opposite to that end wall 14 with which line 16 communicates. Line
18 is equipped with a pump 20 which is operated to withdraw cooled
water from tank 10 and pump it to the location where it is to be
utilized. Line 16 is equipped with a pump 22 which is driven by a
motor 24 which operates in response to a signal generated by water
level control 26 and received by motor 24 via electricity conductor
28. Control 26 operates in response to signals from indicating
points 30 and 32, respectively, via conductors 34 and 36. Point 32
is the lower indicating point and point 30 is the upper indicating
point. If as a result of water withdrawal via line 18 the level in
tank 10 falls below point 32, water level control 26 activates
motor 24 via conductor 28 to operate pump 22 so that water is fed
into tank 10 via line 16. When the water level reaches point 30,
water level control 26 deactivates motor 24 via conductor 28 to
shut off pump 22 whereby the water flow through line 16 into tank
10 is discontinued.
Tank 10 is equipped with a plurality of injector nozzles or lances
38 for the injection of liquid nitrogen into cylindrical tank 10.
Each of the nozzles is vertically oriented. Each of the nozzles is
mounted in side wall 12 along a line defined by the intersection of
side wall 12 with a vertically oriented plane which passes through
the longitudinal axis of tank 10. The nozzles 38 are more or less
uniformly spaced along said line to provide distribution of liquid
nitrogen injection throughout the water. Each of the nozzles has a
single outlet which is in its downstream end. Each of the nozzles
is equipped with a heating element 40 in its lower portion. The
heating elements 40 are connected via leads 42 and conductors 44
and main conductor line 46 to timer 48 which functions to activate
heating elements 40 in accordance with a preset time schedule. The
upper portion of nozzles 38 is covered by insulation denoted 41.
The particular design of the heating elements and the description
of the function of the elements and of the nozzles will be
described in more detail hereinafter.
Communicating with the upstream ends of each of the nozzles 38 are
branch liquid nitrogen supply lines 50, each of which is equipped
with a valve 52. The upstream end of each of these branch lines 50
communicates with a main nitrogen supply line 54 which in turn
communicates via lines 56 and 58 to reservoir 60 for the storage of
liquid nitrogen which can simply be a tank under pressure. Liquid
nitrogen can be supplied to reservoir 60, for example, by tank
trucks. Line 58 is equipped with valves 62 and 64.
Also communicating with liquid nitrogen reservoir 60 is a line 66
which leads into a vaporizer 68 which can simply be an expansion
chamber or heat exchanger. Vaporizer 68 has an outlet line 70 which
contains a valve 72 and communicates at its downstream end with a
line 74 which in turn communicates with line 56. Line 74 is
provided with a valve 76. Also communicating with the upstream end
of line 74 is a line 78 which contains a valve 80. Line 78
communicates at its upstream end with a source of pressurized
air.
Valve 76 is connected via a conductor 82 to a temperature control
84. Valve 64 is connected via a conductor 86 to temperature control
84. Temperature control 84 also communicates via conductors 88 and
90 to a temperature sensing probe 92. Temperature sensing probe 92
can be, for example, a thermocouple and is preferably located close
to the water exit end of tank 10.
Tank 10 is provided with nitrogen gas vent lines 94 which
communicate with its side wall at the top of the tank.
The water in tank 10 is cooled to a predetermined temperature level
for example, 33.degree. to 40.degree. F. by the injection into tank
10 below the water level of liquid nitrogen via nozzles 38.
The nitrogen injection is controlled by temperature control 84
which is activated by signals generaged by temperature sensing
probe 92. When the temperature of the water in tank 10 as sensed by
probe 92 is above the predetermined temperature desired, a signal
is sent via conductors 88 and 90 to temperature control 84 which
operates via connection 86 to open valve 64. During operation
valves 62 and 52 are maintained in open position. As a result of
the opening of valve 64, the liquid nitrogen under pressure in
reservoir 60 flows via lines 58, 56, 54 and 50 into and through
nozzles 38 and into the water in tank 10 to cool said water. When
the temperature of the water in tank 10 reaches the predetermined
desired level as sensed at the temperature sensing point of probe
92 a signal is sent via conductors 88 and 90 to temperature control
84 which operates to close valve 64.
During operation valve 72 is ordinarily maintained open and valve
80 is ordinarily maintained closed. Liquid nitrogen from reservoir
60 which has been introduced via line 66 into vaporizer 68 is
vaporized therein to provide dry nitrogen gas.
Temperature control 84 operates to open valve 76 at the same time
when it operates to close valve 64. As a result of the opening of
valve 76 the nitrogen gas from vaporizer 68 flows via lines 70, 74,
56, 54 and 50 into and through nozzles 38 and emits from the
downstream openings in nozzles 38 below the water level in tank 10.
As a result of nitrogen gas being fed through nozzles 38 during
those periods when liquid nitrogen is not fed through those
nozzles, the water in tank 10 is not allowed to back up into
nozzles 38 whereby freezing of the water in nozzles 38 and plugging
of the same is prevented.
At any time when the temperature level as sensed by temperature
sensing element 92 exceeds the desired level a signal from probe 92
activates temperature control 84 to close valve 76 and open valve
64 whereby liquid nitrogen is again fed into the water in tank 10
and nitrogen gas feed is discontinued.
Pressurized air is maintained available so as to be used in place
of vaporized nitrogen in case the nitrogen supply is low or the
nitrogen vaporizer is not working properly. In other words, the
pressurized air is a back up for the vaporized nitrogen. In the
event that vaporized nitrogen is not utilized, valve 72 is
maintained closed and valve 80 is maintained open whereby
pressurized air is fed through nozzles 38 during those periods when
liquid nitrogen is not supplied through nozzles 38. Preferably the
pressurized air is dry.
Cooling of the water is achieved as a result of the liquid nitrogen
fed into tank 10 vaporizing in the water in tank 10 abstracting
from the water an amount of heat substantially equal to the heat of
vaporization of the liquid nitrogen plus the sensible heat required
to raise the temperature of the resulting nitrogen vapor to the
temperature of the water. The gaseous nitrogen resulting from the
vaporization of liquid nitrogen which has been fed into the tank
and also the nitrogen vapor or pressurized air which has been fed
through nozzles 38 during those periods when liquid nitrogen is not
fed into tank 10, are vented from tank 10 via vent lines 94. The
gas vented via lines 94 is at approximately the temperature of the
water in tank 10 and is saturated with water.
During the operation of the aforedescribed system the water level
is maintained within prescribed limits as aforedescribed.
During the operation of the aforedescribed system heating element
40 is utilized in accordance with a preset time schedule as
previously described to supply heat in the vicinity of the injector
outlet to prevent ice formation at the end of the injector and to
prevent ice from bridging from the side wall of the injector pipe
around the end of the injector. Thus, heating element 40 supplies
heat both at the end of its nozzle and along the side wall of the
nozzle near the end of the nozzle. As previously mentioned the heat
is supplied in accordance with a preset time schedule. In other
words, the heating elements 40 are operated in response to a signal
from timer 48 so that heat is supplied at regularly scheduled
intermittent periods. For example, timer 48 activates switches
whereby electrical current is supplied to heating elements 40, for
example, during a 30 second period out of each minute. When this
period is at an end, timer 48 activates said switches to close
whereby electric current is no longer supplied to heating elements
40. The electric current passes via lead wires described in more
detail hereinafter into heating elements 40 and produces heat as a
result of passing through the resistance offered by elements
40.
Turning now to FIGS. 2 and 3, there is depicted a preferred
injector nozzle and heating element combination. With continuing
reference to FIGS. 2 and 3 the nozzle 38 is shown mounted in the
side wall 12 of a cylindrical tank 10. Nozzle 38 is mounted in side
wall 12 by the use of mounting plate 96 which is welded or
otherwise suitably connected to nozzle 38. Mounting plate 96 is
bolted to side wall 12 by bolts 98. A watertight connection is made
between side wall 12 and plate 96 by the use of gasketing material
100. The nozzle 38 has at its upper end insulating material 41.
Water is prevented from passing between insulating material and
nozzle 38 and freezing on nozzle 38 by radiator hose clamps 102
around and near both ends of insulating material 41. The nozzle 38
has adjacent its downstream portion a heating element 40 which is
described in detail hereinafter. Heating element 40 is connected at
transition joints 104 to leads 42 which are spiralled around
insulation 41 and eventually pass through plate 96 in watertight
fashion to a source of electricity 106. The leads 42 are spiralled
around the outside of insulation 41 so that the leads can yield as
the nozzle expands or contracts due to the temperature of the
material passing through it. If this expansion room is not provided
by the spiralling of the leads, for example, if the leads are
directly run along insulation 41 parallel to the longitudinal axis
of nozzle 38, said leads can crack or break due to said expansion
and contraction.
The heating element depicted in FIGS. 2 and 3 is a preferred
heating element for use within the scope of the present invention.
The heating element 40 is essentially a conductor having a
resistance such that when current is passed through it, heat is
provided. It is essentially a conducting wire with each of its ends
being connected to one of the transition joints 104. In its path
between the transition joints heating element 40 first proceeds in
essentially U-shaped configuration with each of the vertical sides
of the U being positioned parallel to the longitudinal axis of
nozzle 38 and adjacent the outer surface of nozzle 38. The edge of
the side wall of nozzle 38 which defines the outer boundary of the
end of nozzle 38 and the lowermost point at the bottom of the U are
in the same horizontal plane. The vertical portion of the U
farthest from transition joint 104 extends approximately from the
end of the nozzle to a point approximately opposite the transition
joints 104. Starting at this point the heating element 40 is
positioned in a direction transverse to the longitudinal axis of
nozzle 38 but is still maintained adjacent nozzle 38 whereupon it
doubles back still positioned adjacent nozzle 38 but this time in a
direction parallel to the longitudinal axis of nozzle 38 until once
more it reaches the downstream end of nozzle 38 thus forming a
second U-shaped configuration, this one having its base
approximately opposite the transition joints 104. The heating
element then proceeds transversely adjacent the edge of the side
wall at the downstream end of the nozzle 38 whereupon it doubles
back still adjacent nozzle 38 but in a direction parallel to the
longitudinal axis of nozzle 38 whereupon it joins a transition
joint 104. This doubling back provides a third U-shaped
configuration as part of the path of the heating element. The
transverse dimension of each of the U-shapes is approximately equal
in length to and opposite an inner radius of nozzle 38. Just
previous to joining transition joints 104 the heating element turns
outwardly from the outer surface of nozzle 38 so that transition
joints 104 are not adjacent nozzle 38. Thus the heating element 40
depicted in FIGS. 2 and 3 follows the path consisting essentially
of three U-shaped configurations in sequence with the first and
third U-shaped configurations being essentially parallel and the
second U-shaped configuration being formed by the joining of the
inner vertical legs of each of said first and third configurations,
each of said vertical legs extending in a direction parallel to the
longitudinal axis of the nozzle, with the lower end of the base of
each of the first and third U-shaped configurations being
essentially in a plane parallel to the end of the nozzle, the path
being adjacent the outer surface of the nozzle, except just
previous to where the path ends at transition joints 104 at which
point the path at each end turns slightly outwardly from said
nozzle. A heating element of this configuration and positioning is
suitable to prevent ice formation at the end of nozzle 38 and to
prevent ice from forming along the side surfaces of nozzle 38 which
might bridge from said side surface around the end of nozzle
38.
A suitable variation of the heating element depicted in FIG. 2 is
shown in FIG. 2A. In FIG. 2A the U-shaped portions of the heating
element adjacent the end of nozzle 38 have the upper surface of
their bases substantially lying in a plane containing the end of
nozzle 38 as distinguished from FIG. 2 wherein the lower surface of
said U-shaped portions substantially lies in said plane.
Nozzles having other suitable heating elements are depicted in
FIGS. 4 and 5.
In FIG. 4 there is shown a nozzle 38 mounted in a mounting plate
96, the nozzle having surrounding its upstream portion insulation
41 with a watertight seal being provided between nozzle 38 and
insulation 41 by radiator hose clamps 102. Leads 42 spiral around
insulation 41 and pass through mounting plate 96 to source of
electricity 106. The leads 42 are connected to heating element 40
via transition joints 104. In the embodiment of FIG. 4 the heating
element 40 spirals around nozzle 38 until it reaches a point
adjacent the end of nozzle 38 whereupon it doubles back spiralling
around nozzle 38 so that the doubled back spiral portion is
essentially parallel to the first described spiral portion. A plan
view of FIG. 4 is shown in FIG. 6. In FIG. 6 the mounting plate 96
is shown containing four openings 108 through which bolts can be
passed to fasten the plate to a water supply tank wall.
In FIG. 5 there is depicted a nozzle 38 with insulation 41 held in
place by radiator clamps 102 having a heating element 40 which is
connected at transition joints 104 to leads 42. The heating element
proceeds in a path adjacent the outer surface of the lower portion
of the outer surface of nozzle 38 in spiral fashion around said
outer surface of nozzle 38 with one of the transition joints 104
being adjacent the downstream end of nozzle 38.
It is emphasized that the vertical positioning of the nozzles with
respect to the water supply tank 10 is an important aspect of one
of the embodiments of the present invention. If the nozzles are
positioned horizontally instead of vertically the turbulence caused
by the emanating liquid nitrogen can cause said water supply
reservoir to be unstable.
The following example further illustrates a preferred water cooling
method and apparatus within the scope of the present invention.
EXAMPLE
The system and method depicted in FIG. 1 is utilized in this
example. The heating element on each nozzle has a configuration ad
depicted in FIG. 2A.
With reference to FIG. 1, the tank 10 is 50 feet long and has a 10
foot diameter. It holds 20,000 gallons. Each of the nozzles extends
radially into the tank a distance of 7 feet 3 inches. Ten nozzles
are employed. Each of these nozzles is made of three-four inch
nominal brass pipe. Each heating element is bonded to the outer
surface of its nozzle with silver solder. Each heating element
extends in a direction parallel to the longitudinal axis of its
nozzle a distance of 8 inches. The leads to each heating element
spiral around the insulation 41 three times. Vent lines 94 each
have 18 inch inside diameters. The leads 42 are M-I cable.
Water enters the tank 10 at 65.degree. F. The system and method of
FIG. 1 is utilized to cool this water to 35.degree. F. The cooled
water is utilized to prepare concrete. The concrete is prepared in
9 cubic yard batches. Two hundred and sixty-five gallons of water
are utilized to prepare a 9 cubic yard batch of concrete.
35.degree. water is sufficient to cool the concrete mix to a
temperature less than 80.degree. F. even though the sand and stone
ingredients of the concrete are at 92.degree. F.
The system is operated continuously. For each 9 yard batch, 37.8
pounds of liquid nitrogen is injected through each of the 10
nozzles into the mass of water in tank 10. The heating elements are
activated 50 percent of the time with heat being supplied during 30
continuous seconds of each minute and then no heat being supplied
for 30 continuous seconds. Each heating element is on for one half
of each hour and during that period consumes 1 kilowatt-hour of
electric energy.
As a result of the heating element functioning the water is cooled
to 35.degree. F. by the liquid nitrogen injection without water
freezing in or around any of the nozzles to plug said nozzles. As a
result of the leads being spiralled around the insulation, said
leads do not crack or break due to contraction or expansion of the
nozzles during operation.
If 33.degree. F. water is desired, and sufficient liquid nitrogen
is added to achieve this temperature, 1.8 kilowatt-hours of
electric energy should be consumed by the heating element of each
nozzle during each one half hour period the heating element is on
to keep the nozzle free from plugging.
More cooling can be provided by the utilization of the spent
nitrogen emanating from vent lines 94 to cool the stone ingredient
by introducing the spent nitrogen into the bin containing the stone
ingredient and then exhausting the same.
The invention may be embodied in other specific forms without
departing from the spirit or essential characteristics thereof. For
example, the nozzles can be adjustable. In the production of
concrete additional cooling may be supplied, for example, by adding
some of the water as ice in the mixer or by spraying liquid
nitrogen on the stone and/or sand ingredients or by collecting
spent nitrogen which emanates from vent lines 94 and conducting
this spent nitrogen to the stone ingredient to provide some cooling
to said ingredient. Beside variations in the nozzle and variations
in the method of providing cooling for concrete making, many other
variations come within the spirit and scope of the invention. For
example, the heating element can be of other specific
configurations than those described as long as the operation of
said elements keeps the end of its nozzle free from ice. Moreover,
inert gas other than nitrogen or air can be used to keep nozzles 38
clear when liquid nitrogen is not being injected; for example, dry
helium or argon can be utilized. Thus the present embodiments are
to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the
appended claims rather than by the foregoing description and all
changes that come within the meaning and range of equivalency of
the claims are therefore intended to be embraced therein.
* * * * *