Note: Descriptions are shown in the official language in which they were submitted.
CA 02329949 2000-12-29
Attorney Docket No.: S228.103.101
HYDRAULIC OIL COOLER AND
SUPPLYING VESSEL PRESSURE STABILIZER
CROSS REFERENCE TO RELATED APPLICATION
The subject matter of this application is related to the subject matter of
U.S.
provisional patent application no. 60/174,138, filed December 31, 1999,
priority to which is claimed under 35 U.S.C. 119(e) and which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the invention relate to improvements in pumping fluids
from tanks or other supplying vessels. Specific aspects of the invention, for
example, relate to pumping propane from a vehicle, such as a bobtail or
tank truck, with improvements in e.g. thermal characteristics and pump
operation. Other examples will be described as well.
2. Description of Related Art
Liquefied compressed gases such as propane are generally transported via
truck primarily in two different ways. The first way is via a transport. A
transport is a trailer that holds approximately 7,000-10,000 gallons of liquid
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Attorney Docket No.: 5228.103.101
propane. The transport is used to fill outlying storage tanks and large
industrial tanks. The second way is via a straight truck, which the propane
industry typically calls a bobtail. The bobtail typically holds less than
3,500 gallons of liquid propane and is used to fill residential and small
business propane tanks.
When a transport unloads, the operator generally will connect two hoses
between the transport and the storage tank. The first hose connected is
called the vapor hose and the second is called the discharge hose. The
purpose for the vapor hose is to allow the vapor pressures between the
transport and the storage tank to equalize and to allow vapor pressure to be
pushed back into the transport vapor space while they are pumping. This
equalizes the pressures and allows the liquid product pump to pump at a
higher rate and lower pressures, which minimizes noise and internal
damage to the propane pump.
When a bobtail unloads, the operator typically uses only a discharge hose.
Most bobtails do not have a second vapor hose. Not having the vapor hose
causes two things to happen. First, as the propane pump on the bobtail
pumps liquid propane from the bobtail into the storage tank, the pressure in
the storage tank continues to rise and causes back pressure on the discharge
line. This back pressure causes the discharge line pressure to continue to
rise, causing the pump to work harder and thus reducing the flow rate and
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increasing the wear of the propane pump. Second, as the propane pump
pulls product out of the bobtail tank it creates a vacuum inside the bobtail
tank. This vacuum creates bubbles in the propane which are then pulled
through the propane pump. As these bubbles are pulled through the
propane pump they compress and then expand rapidly, potentially causing
damage to the internal vanes and rotor of the propane pump. These bubbles
reduce the flow rate of the pump and create a higher level of pump noise.
Liquid products that do not change state as readily, such as fuel oil and
refined fuel, are transported via truck primarily in two different ways. The
first way is via a transport, described earlier. The second way is via a
straight truck. The straight truck carries 500-5,000 gallons of product. The
straight truck typically delivers to residential customers and to small
industrial customers.
With liquid products that do not change state, both the transport and the
straight truck unload in approximately the same way. The operator
connects a single discharge hose between the transport or straight truck to
the storage tank. Once this has been accomplished, the operator then starts
the pump and pumps the liquid product into the storage tank. Since this
type of liquid is not pressurized to maintain it as a liquid, the transport,
straight truck and storage tanks can all be vented to atmosphere. This
eliminates the need for a vapor hose.
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Thus, the propane bobtail delivery market and the fuel-oil and refined-fuels
tank-truck delivery market, for example, are similar in that typically they
both use a tandem-axle-style truck with a multi-thousand gallon tank
mounted on the chassis. These vehicles are used to deliver typically small
quantities of e.g. propane, fuel oil, diesel fuel and gasoline to e.g. homes,
farms and small businesses.
Currently, there is a movement in these industries to change from driveline-
driven product pumps to hydraulic drives. This change is coming from a
number of areas, e.g. safety, maintenance and a need to either mount the
product pump in a location that cannot be easily driven by a driveshaft or a
need for two or more product pumps on a truck. The tank-truck market is
shifting towards having larger and multicompartment tanks on their trucks.
This shift allows more efficient use of their trucks and their employees.
It would be desirable to take advantage of the movement to change from
driveline-driven product pumps to hydraulic drives, to further capitalize on
the attendant advantages. Additionally, a need exists to diminish the
problems of back pressure and vacuum-induced bubbles in e.g. propane,
which bubbles are then pulled through the propane pump. It would also be
desirable to diminish the disadvantages caused by using a fan for cooling,
e.g. noise, vibration/resonance, and maintenance/upkeep concerns.
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SUMMARY OF THE INVENTION
To achieve the above and other goals, one embodiment of the invention
uses the product that the customer is pumping, e.g. propane, to cool the
hydraulic oil used to run the pump. A liquid-to-liquid heat exchanger
receives the hydraulic oil line and a line containing the pumped product.
Approximately two gem of product can be pumped through the heat
exchanger, according to one embodiment. The two liquids are separated by
thin channels of e.g. stainless steel or another material. The heat exchanger
cools the hydraulic oil and warms the customer's liquid product.
Embodiments of the invention have particular advantages in e.g. the
propane industry. Propane is heated, vaporized and then pumped back into
the top of the supplying tank. This vaporized propane increases pump flow
rates, reduces cavitation and increases pump life. These advantages are
obtained, according to embodiments of the invention, with no fan motor,
better product pump performance, longer product pump life, and smaller
and lighter pump weights.
The theory behind embodiments of the invention is twofold for e.g. propane
types of application. First, by using the liquid propane as the cooling agent
inside the liquid-to-liquid heat exchanger, the hydraulic oil is kept at a
safe
operating temperature without the use of a cooling fan. Second, as the
hydraulic oil passes through the heat exchanger it heats the liquid propane.
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The heated liquid propane is boiled or vaporized and then pumped back
into the vapor space, or liquid space, in the bobtail tank. By reintroducing
this vapor back into the bobtail tank, the problems that were stated above
are minimized. Embodiments of the invention decrease the length of time
during which product can be unloaded, stabilize the vapor pressure in the
bobtail tank, reduce pump wear and noise, and cool the hydraulic system
without the need for any type of cooling fan.
Embodiments of the invention for liquid products that do not as readily
change state regulate a small amount of the liquid product being pumped
through the heat exchanger. As the liquid passes through the heat
exchanger, it cools the hydraulic oil. The heated liquid product is the
reintroduced back into e.g. either the transport or straight truck tank or
back
into the discharge line of the pump.
Embodiments of the invention provide significant advantages, in that they
can cool the hydraulic oil without the need for a cooling fan and can aid in
the pumping of liquids that become more difficult to pump in colder
climates.
Embodiments of the invention can be described as a combination of a
hydraulic oil cooler and a supplying vessel pressure stabilizer.
Embodiments of the invention can be used in applications that require
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hydraulic oil to be cooled while it is operating a product pump that is
pumping some type of liquid product. The hydraulic oil is cooled via a
"liquid-to-liquid" heat exchanger, for example. This heat exchanger can
have up to at least three channels allowing up to at least three different
liquids to pass through it at any one time.
On one side of the heat exchanger is the hydraulic oil and on the other
sides) are one or more liquid products that are being pumped by the
product pump(s). The liquid products absorb the heat of the hydraulic oil.
In effect, embodiments of the invention are cooling the hydraulic oil and
heating the amount of liquid product that is being pumped through the heat
exchanger. This device will work when the temperature of the liquid
product being pumped is less than the maximum desired hydraulic oil
temperature. Different types of liquids at different flow rates affect the
1 S cooling capacity of the heat exchanger and the amount of heat being
transferred into the liquid product being pumped. Hydraulic oil flow rates
at varying pressures affect the amount of heat (BTU's) that are produced.
At least two different types of liquid products can be used with this device.
The first is a "non-state-changing" liquid, as referenced above. This type
of liquid does not change its state when the amount of heat (BTU's) that a
hydraulic system creates is dissipated and absorbed by the liquid. For
example, embodiments of the invention simply add a fixed amount of
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BTU's to diesel fuel. These added BTU's increase the temperature of the
diesel fuel to a predetermined and controlled safe temperature. The second
type of liquid, the "state-changing" liquid, begins to boil or vaporize as its
temperature is changed. These types of liquids are typically referred to as
liquefied compressed gases. For example, propane will boil or vaporize as
heat is introduced to it.
According to embodiments of the invention, the liquid product being
pumped through the heat exchanger is reintroduced back into the supplying
vessel once it has circulated through the heat exchanger. Depending upon
the product, it will enter back into the supplying vessel as a warmed-up
liquid or as a boiling liquid or vapor. This vapor can be extremely
beneficial to certain types of supplying vessels to aid in the pumping
process. This benefit will be described in detail, further into this
description.
Embodiments of the invention contain a "liquid-to-liquid" heat exchanger,
a hydraulic reservoir, and a hydraulic oil filter. These parts are
manufactured and assembled into a package that is compact, light-weight
and easy to install for the customer. Embodiments of the invention also
diminish many of the problems referenced above, e.g. back pressure,
vacuum-induced bubbles, cavitation, noise, vibration/resonance,
maintenance/upkeep concerns, and the like.
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Additional features and advantages according to embodiments of the
invention will become apparent from the remainder of this patent
application.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will be described with respect to the figures,
in which like reference numerals denote like elements, and in which:
Figure 1 is a schematic view of a cooler/stabilizer according to an
embodiment of the invention;
Figure 2 is a schematic view of a cooler/stabilizer having a
temperature-sensing, heat-generating control block according to an
embodiment of the invention;
Figure 3 is a detailed view of the temperature-sensing, heat-
generating control block of Figure 2;
Figure 4 is a schematic view of a cooler/stabilizer having a
pressure-sensing, heat-generating control block according to an
embodiment of the invention;
Figure 5 is a detailed view of the pressure-sensing, heat-generating
control block of Figure 4;
Figure 6 is a schematic view of a cooler/stabilizer having a
pressure-sensing, shut-off valve control block according to an embodiment
of the invention;
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Attorney Docket No.: 5228.103.101
Figure 7 is a detailed view of the pressure-sensing, shut-off valve
control block of Figure 6; and
Figure 8 is a schematic view showing a cooler/stabilizer according
to an embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Turning first to Figure 1, fluid handling system 10 according to an
embodiment of the invention includes supplying vessel or tank 15 for
holding first fluid 20, e.g. propane, fuel oil, diesel fuel, gasoline, or
other
liquid. Both liquefied compressed gases and liquid products that do not
change state as readily are contemplated for use as first fluid 20. Supplying
vessel 1 S also defines vapor space 25 disposed above first fluid 20.
Discharge flow path 30 is in fluid communication with supplying vessel 15.
Discharge flow path 30 is disposed to receive first fluid 20 from supplying
vessel 15 for discharge from supplying vessel 1 S and, according to
embodiments of the invention, from fluid handling system 10 to e.g.
receiving tanks or the like at homes, farms, small business, etc. According
to embodiments of the invention, discharge flow path 30 is defined, at least
in part, by suction inlet port or pump inlet port 35, product pump 40 and
pump outlet discharge line 45. Product pump 40 is a pumping mechanism
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Attorney Docket No.: 5228.103.101
that is constructed and disposed to move first fluid 20 along discharge flow
path 30.
Return flow path 50 is in fluid communication with discharge flow path 30
and, ultimately, with supplying vessel 15. Return flow path 50 is disposed
to receive first fluid 20 from discharge flow path 30 for return to supplying
vessel 15. According to the illustrated embodiment, return flow path 50 is
defined, at least in part, by product/coolant line 55, which intersects pump
discharge line 45 at intersection point 60, heat exchanger 65, and
liquid/vapor return line 70. Product/coolant line 55 is connected to heat
exchanger 65 via flow control 63.
Fluid handling system 10 also comprises heat-exchange flow path 75,
which is disposed to contain second fluid 78, which is e.g. hydraulic fluid
or oil for actuating pump 40. Second fluid 78 is free of fluid
communication with first fluid 20, according to embodiments of the
mvenhon.
According to the illustrated embodiment, heat-exchange flow path 75 is
defined, at least in part, by hydraulic return line 80, which is connected via
hydraulic filter 85 to hydraulic tank assembly 90. Hydraulic tank assembly
90 includes hydraulic breather 95 and site/level oil gauge 100, according to
the illustrated embodiment. Hydraulic suction line 105 connects hydraulic
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tank assembly 90 to hydraulic pump 110, which is connected to power
take-off (PTO) 115. Hydraulic pressure lines 120 and hydraulic flow and
PSI block 125 connect hydraulic pump 110 to deliver second fluid 78 for
actuating product pump 40 via hydraulic motor 130, which is mounted by
hydraulic motor mounting assembly 135. Thus, pump 40 is in fluid
communication with heat-exchange flow path 75.
Case drain line 138 connects hydraulic tank assembly 90 to hydraulic motor
130.
In operation, pump 40 is activated to move first fluid 20 along discharge
flow path 30 for discharge from supplying vessel 15 and/or fluid handling
system 10. First fluid 20 in discharge flow path 30 is in the form of a liquid
at intersection point 60 according to embodiments of the invention, as is
first fluid 20 in return flow path 50 at point 60.
The temperature of first fluid 20 in return flow path 50 is cooler upon
entering heat exchanger 65 than second fluid 78 in heat-exchange flow path
75. In heat exchanger 65, thermal transfer occurs between first fluid 20 and
second fluid 78. According to one embodiment, second fluid 78, e.g.
hydraulic oil, is cooled by first fluid 20, e.g. propane, and first fluid 20
is
heated by second fluid 78. Thus, heat exchanger 65 is constructed and
disposed to cause a temperature change in both first fluid 20 and second
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fluid 78, and the temperature of first fluid 20 is generally less than the
maximum desired temperature of second fluid 78.
In summary, fluid handling system 10, which can be disposed on a vehicle,
such as a truck, comprises tank 15 for holding fluid product 20, pump 40
for pumping fluid product 20 from tank 15, pump 40 being driven by
hydraulic fluid 78, and heat exchanger 65 for using fluid product 20 to cool
hydraulic fluid 78. Fluid product 20 can be propane. Further, heat
exchanger 65 heats propane or other first fluid 20 and causes it to vaporize.
The vaporized propane in liquid/vapor return line 70 than is pumped and
returned either to vapor space 25 or the liquid space of tank 1 S. In other
words, heat exchanger 65 heats fluid product 20 and returns it to tank 15.
Three control blocks can be offered as options to the Figure 1 embodiment,
as will now be described with respect to Figures 2-7.
The first of the three control blocks is temperature-sensing, heat-generating
block 140, shown generally in Figure 2 and in detail in Figure 3. Block 140
is disposed in heat-exchange flow path 75, just before heat exchanger 65, in
the illustrated embodiment. Block 140 includes valve body 145,
temperature sensing cartridge 150, heat-generating cartridge 155, hydraulic
oil inlet and outlet ports 160, 165, hydraulic oil pressure port 168, and
hydraulic oil pressure gauge 170. Block 140 senses the temperature of the
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hydraulic oil or other second fluid 78 by temperature sensing cartridge
valve 150. It then will internally either route the e.g. hydraulic oil over
hydraulic heat generating cartridge valve 155 and then into heat exchanger
65, or it will route the hydraulic oil directly to heat exchanger 65,
bypassing
hydraulic heat-generating cartridge valve 155. The temperature at which
block 140 switches the routing from one to the other can be changed to
meet the requirements for a particular environment or application.
Thus, temperature sensor 150 is in communication with heat-exchange flow
path 75 for sensing the temperature of second fluid 78. Heat generator 155
is also in communication with heat-exchange flow path 75, and is
constructed and disposed for heating second fluid 78 in response to an
indication from temperature sensor 150.
Block 140 presents significant advantages. A cold outside air temperature
or other ambient environment produces a colder tank and therefore less
vapor pressure within the tank. In other words, the fluid product within the
tank is more condensed. This cooler temperature causes pump 40 to draw a
vacuum within tank 15 more quickly, potentially starting cavitation in
pump 40 at an earlier time. Heating second fluid 78 causes increased
thermal transfer to first fluid 20, increasing the reduced vapor pressure in
tank 15 and tending to diminish the cavitation problem. Additionally,
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heated fluid 78 provides e.g. start-up advantages in fluid handling system
10.
The second unique, optional control block for fluid handling system 10 is
pressure-sensing, heat-generating control block 175, shown in Figure 4 in
heat-exchange flow path 75 and shown in more detail in Figure 5. Block
175 senses vapor pressure in supplying vessel 15 via sensing line 180
routed between vessel 15 and control block 175. Via product sensing port
185 and end cap 187, which includes a filter, the vapor pressure in
supplying vessel 15 pushes on piston 190. Piston 190, in turn, moves
against bias spring 195 disposed within piston chamber 200. This
movement determines a pass-through orifice size, by moving orifice spool
205, anchored in spool block 210. Hydraulic oil or other second fluid 78
enters block 175 at inlet port 215, passes through the orifice whose size is
determined in the manner described above, and then out through outlet port
220 enroute to heat exchanger 65. The size of the orifice determines the
amount of hydraulic heat transferred in heat exchanger 65. The lower the
product vapor pressure, the smaller the orifice size, which in turn equals a
higher hydraulic oil temperature. The maximum pressure limitations of
supplying vessel 15 will determine the maximum amount of hydraulic heat
that can be generated through control block 175. Thus, control block 175
includes a pressure sensor constructed and disposed to indicate vapor
pressure in supplying vessel 15, and a temperature regulator in
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communication with heat-exchange flow path 75, the heat generator being
constructed and disposed for heating second fluid 78 in response to an
indication from the pressure sensor. According to one embodiment, the
pressure sensor and temperature regulator are disposed as an integral unit
175 in fluid communication with both return flow path 50 (via sensing line
180) and heat-exchange flow path 75.
The third unique, optional control block is pressure-sensing, shut-off
control block 260, illustrated in Figure 6 in return flow path 50 and
illustrated in more detail in Figure 7. Block 260 is designed to
mechanically shut off the flow of cooling liquid (e.g. first fluid) 20 if and
when the pressure in supplying vessel 15 reaches a predetermined pressure.
This shut-off protects supplying vessel 15 form over-pressurization.
Block 260 senses vapor pressure in supplying vessel 15 via sensing line
265, which is in fluid communication with return flow path 50 and thus is
in fluid communication with supplying vessel 15. The vapor pressure in
supplying vessel 15 pushes against piston 290, via product sensing port 285
and end cap 287 (which includes a filter). Piston 290 in turn moves against
bias spring 295 disposed within piston chamber 300. This movement
determines whether or not spool 305 moves within spool block 310 to a
position that does or does not allow first fluid 20 (product/coolant) to flow
from inlet port 315 to outlet port 320 and on to heat exchanger 65. Thus,
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according to this embodiment, fluid handling system 10 includes a pressure
sensor constructed and disposed to indicate vapor pressure in supplying
vessel 15, and a flow regulator in fluid communication with return flow
path 50, the flow regulator being constructed and arranged to decrease flow
of first fluid 20 in return flow path 50 in response to a high-pressure
indication from the pressure sensor. The pressure sensor and flow regulator
are disposed as an integral unit 260 in fluid communication with return
flow path 50.
Returning to Figure 6, according to this embodiment heat exchanger 65 is
in fluid communication with engine 330 via engine coolant return lines
335, 340. Engine coolant bypass valve 345, preferably a ball valve, allows
bypass of heat exchanger 65 via engine coolant bypass line 348 if desired.
Power take-off 350 draws power off engine 330 for activating pump 40 via
driveline 355. Thus, fluid handling system 10 according to this
embodiment uses engine coolant as an equivalent to the previously
described second fluid 78. Alternatively, hydraulic oil or other fluids can
also be used in this embodiment in the manner described previously.
Figure 8 shows additional aspects of fluid handling system 10, including
system casing 360, fittings 365 for connection with pump 110, and fittings
370 for connection with hydraulic motor 135 and pump 40. Pump 110,
according to this embodiment, can have a pump speed of 1,500 rpm,
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producing 16 gpm at 1,500 PSI. PTO 115 can accommodate 1,300 engine
rpm, according to one embodiment. Hydraulic motor 135 optionally can be
attached to pump 40 by hydraulic adapter 375, and pump 40, according to
one embodiment, is a 10 HP pump at 640 rpm. Of course, other sizes,
speeds and related parameters are contemplated according to embodiments
of the invention.
While embodiments of the invention have been described with reference to
particular preferred embodiments, the invention is not limited to the
specific examples given. Use with a wide variety of tractors, trailers, and
other vehicles and devices and with a wide variety of liquids is
contemplated. Various materials can be used according to the invention,
e.g. stainless-steel componentry, or any material having strength and
durability sufficient to withstand severe operational conditions. Various
modifications and changes will occur to those of ordinary skill upon
reading this disclosure, and other embodiments and modifications can be
made by those skilled in the art without departing from the spirit and scope
of the invention.
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