Note: Descriptions are shown in the official language in which they were submitted.
1146Q61
NITROGEN LIQUID TO GA-S-CONVERTER
-
Bac~ground of the Invention
It is old to convert liquid nitrogen to gaseous nitrogen
to treat and stimulate oil and gas wells. The converter must
pump the nitrogen to high pressures, such as 10,000 psi, and
heat the liquid nitrogen to convert it to gas. However, the
environment around oil and gas wells is frequently hazardous
and therefore the use of open flames or high temperatures to
convert the liquid to gas is dangerous.
The present invention is directed to a self-contained
flameless nitrogen liquid to gas converter which pressurizes
the nitrogen and converts it to a gaseous state for use in an
oil and gas field environment.
Summary
In broade8t term8, the pxesent lnvention is an improve-
ment in a nitrogen liquid to gas converter having a diesel
engine prime mover in which the heat rejection of the engine
water and engine exhaust are utilized to convert liguid nitrogen
to the gaseous state, hydraulio p.ump mean~..d~iv.en by the diesel
.engine, the hydraulic pump means driving hydraulic motors, one
of the motors driving a nitrogen pump and another of said motors
driving an air fan for passing air over a nitrogen-air heat
exchanger, the improv~ment of obtaining heat from hydraulic
fluid comprising at least one hydraulic pump and driven
hydraulic motor being in a hydraulic circuit which includes a
hydraulic oil-air heat'exchanger and means for increasing the
heat of the hydraulic fluid for heating the air and thus
heating the nitrogen.
In more detail, in a preferred embodiment, the present
invention is directed to a nitrogen liquid to gas converter
having a liquid nitrogen inlet and a nitrogen pump actuated by
a hydraulic motor for pressurizing the nitrogen. A nitrogen-
.~
1146~1!61
air heat exchanger is connected to the nitrogen pump and an air
fan passes air over the exchanger for adding heat to the
nitrogen and converting the liquid to gaseous nitrogen.
Hydraulic pumps actuate the motors and a diesel engine drives
the hydraulic pumps. Heat for heating the air and thus the
nitrogen is obtained from an engine exhaust-air heat exchanger
and an engine water-air heat exchanger positioned in the air
stream upstream from the nitrogen heat exchanger. Further heat
is obtained from a hydraulic oil-air heat exchanger connected
to the hydraulic pumps and motors and positioned in the air
upstream from the nitrogen heat exchanger. Additional heat
is obtained from means for increasing the pressure in a
hydraulic oil circuit for increasing the heat of the hydraulic
fluid for heating the nitrogen.
Preferably the means for increasing the heat of the
hydraulic fluid is a variable hydraulic pressure control valve
which is preferably positioned downstream from a pump.
In other terms, preferably the improvement is for
obtaining heat from hydraulic fluid in which at least one of
the hydraulic pumps and its driven hydraulic motor is in a
hydraulic circuit which includes a hydraulic oil-air heat
exchanger and variable means for increasing pressure in the
hydraulic circuit for increasing the heat of the hydraulic
fluid for heating the air and thus heating the nitrogen.
Preferably, also, the hydraulic circuit includes a hydraulic
oil reservoir downstream of the hydraulic oil-air heat ex-
changer. In addition, hydraulic fluid from other pumps and
motors may be transmitted through the hydraulic oil-air heat
exchanger.
In the pre~erred embodiment, the heat exchange equipment
is axially aligned and positioned in series in the air from the
upstream to the downstream in the following order: hydraulic
~- 2 -
1146a!61
oil-air heat exchanger, engine water-air heat exchanger, engine
exhaust-air heat exchanger, nitrogen-air heat exchanger, and the
air fan.
Other features and advantages will be apparent from the
followina description of a presently preferred embodiment of
the invention, given for the purpose of disclosure and taken in
conjunction with the accompanying drawings.
Brief Description of the Drawings
Figure 1 is a front elevational view of the preferred
apparatus of the present invention omitting certain flow lines
for convenience,
Figure 2 is a back elevational view of the apparatus of
Figure 1,
)o
~1 - 2a -
~6g~61
1 Figure 3 is a cross-sectional view taken along the
line 3-3 of Figure 1,
Figure 4 is a cross-sectional view taken along the
line 4-4 of Figure 1, and
Figure 5 is a hydraulic schematic of the present
apparatus.
Description of the Preferred Embodiment
Referring now to the drawings, and particularly to
Figures 1-4, the reference numeral 10 generally indicates the
nitrogen liquid to gas converter which is mounted on a suitable
self-contained support 12 whereby the converter may be suitably
transported for treatment of various oil and/or gas wells.
suitable prime mover 14, such as a Detroit diesel engine Model
6V92T is mounted on the support 12 for providing all of the
power necessary for the converter 10. A plurality of hydraulic
pumps 16, 18 and 20 are mechanically connected to and actuated
by the engine 14 which in turn provide the motive force for
driving various hydraulic motors for actuating one or more
liquid nitrogen pumps and an air fan. Pump 16 may be model 24
sold by Sunstrand, pump 18 may be model 26 sold by Sunstrand,
; and pump 20 may be model P25X-342 Bert 15-2 sold by Commercial
Shearing.
Pump 16 in turn drives a hydraulic motor 22 (Figure
5), such as Volvo, which in turn drives an air suction fan 24
(Figures 2 and 3) which draws air over a nitrogen-air heat
exchanger 26 for adding heat to the liquid nitrogen for con-
verting the liquid nitrogen to a gaseous state. Pump 18 drives
a hydraulic motor 28, such as model 27 manufactured by Sun-
strand, which in turn drives a conventional nitrogen pump 30.
30 The pump 20 drives a hydraulic motor 32, such as model MF 15-
3021 manufactured by Sunstrand which in turn drives a conven-
tional liquid nitrogen booster pump 34.
--3--
~i46~P6~
1 Referring now to Figures 2 and 3, an engine exhaust-
air heat exchanger 34 is positioned in the air stream up-
stream from the nitrogen heat exchanger 26 for heating the
air for assisting in converting the liquid nitrogen to gaseous
nitrogen. The engine exhaust 35 (Figure l) is covered with
insulation (not shown) and is in the heat exchange relationship
with the exchanger 34 and the exhaust is then passed through
weathercap 37. The heat exchanger 34 thus functions to utilize
the waste heat from the exhaust of the diesel engine 14 for
heating the nitrogen and additionally reduces the temperature
of the exhaust to approximately 75~ F. above ambient temperature
for preventing the exposure of a high temperature exhaust to
the surrounding environment of an oil and/or gas well.
In addition, an engine jacket water exhaust-air heat
exchanger 36 is positioned in the air upstream from the nitrogen
heat exchanger 26 for providing additional heat for heating the
air and converting the liquid nitrogen to gas. The exchanger
36 is connected to the ensine cooling water through line 41
(Figure l).
In addition, a hydraulic oil-air heat exchanger 38 is
connected to various hydraulic pumps and motors, as will be
more fully described hereinafter, and is positioned in the air
upstream from the nitrogen heat exchanger for still providing
additional heat for heating the air and thus the nitrogen. It
is to be noted that the air fan 24 and heat exchangers 26, 34,
36 and 38 are coaxially aligned to provide an efficient flow of
air by providing a straight flow of the air and maintain
uniform air velocity across the surfaces of the heat exchangers
26, 34, 36 and 38. Furthermore, the fan and heat exchangers
are positioned in series in the air from upstream to downstream
in the following order: hydraulic oil-air heat exchanger 38,
engine water-air heat exchanger 36, engine exhaust-air heat
--4--
~146~61
1 exchanger 34, whereby the incoming air stream is heated pro-
gressively to higher temperatures for greatest efficiency.
Referring to Figure 4, a liquid nitrogen inlet 42 is
provided in communication with the booster pump 34 whereby the
liquid nitrogen is pressurized and passed to a supply header 44
for the pump 30 wherein the liquid is further pressurized and
passed to a discharge header 46. From the header 46 the
pressurized liquid nitrogen is passed to the nitrogen-air heat
exchanger 26 where the nitrogen is converted to a gaseous state
by the heat exchanged from the flowing air. From the exchanger
26, the gaseous nitrogen is then discharged as required.
Referring now to Figure 5, a schematic of the hydraulic
circuit is best seen. A reservoir 50 of hydraulic fluid is
provided for supplying and receiving hydraulic fluid from the
circuits. One of the circuits 52 includes the hydraulic pump
20 which supplies fluid to actuate the hydraulic motor 32 which
drives the nitrogen booster pump 34. A second hydraulic
circuit 54 includes the hydraulic pump 18 which provides
hydraulic fluid for actuating the hydraulic motor 28 which
drives the nitrogen pump 30. Another hydraulic circuit 56
includes the hydraulic pump 16 which provides fluid for actuating
the hydraulic motor 22 which drives the air suction fan.
It is desirable to obtain as much heat from the
converter 10 as possible for converting the liquid nitrogen to
gas. In addition to obtaining heat from the exhaust and water
of the diesel engine 14, heat is extracted from the hydraulic
oil of the various hydraulic pumps and motors by virtue of the
hydraulic oil-air heat exchanger 38. Thus, the hydraulic fluid
in circuit 52 flowing through the pump 20 and motor 32 is
transmitted directly through the heat exchanger 38 prior to
entering the reservoir 50. On the other hand, circuits 54 and
56 may operate at higher pressures in a closed circuit between
--5--
--- 1146~
1 the pumps and motors. Makeup fluid for case drain is obtained
through makeup lines 55 and 57, respectively. The case drain
from motor 28 is transmitted through line 60 and combined with
the case drain from pump 18 in line 61 which is then trans-
mitted to the heat exchanger 38. Similarly, the case drain in
motor 22 is transmitted by line 62 and combined with the case
drain in pump 16 through a line 63 to the heat exchanger 38.
In addition, the present invention includes means for
obtaining increased heat from the hydraulic fluid for heating
the nitrogen. Preferably, means are provided connected in at
least one of the hydraulic circuits for increasing the pressure
in the hydraulic circuit thereby increasing the heat of the
hydraulic fluid which is transmitted to the hydraulic oil-air
heat exchanger for heating the nitrogen. Thus, referring to
circuit 52, a variable meanC for increasing the pressure in the
hydraulic circuit such as a relief valve 70, such model P8819-
06 from Rivett Company, is provided which can provide a varia-
ble restriction in the circuit 52 causing the pump 20 to work
at greater pressures and thereby creating extra heat in the
hydraulic fluid if the pressure is increased sufficiently by
the valve 70. Valve 70 is controlled through control line 73
by manually actuated pressure control valve 72. Therefore, by
merely adjusting the pressure control valve 72, valve 72 is
controlled so that additional heat may be supplied for heating
the nitrogen without providing any dangerous spark igniting
means in the hazardous environment surrounding the oil and/or
gas well.
Therefore, the present invention provides a liquid
to gas nitrogen converter which is self-contained, has a
single prime mover and utilizes the waste heat of the diesel
engine including both its cooling water and exhaust, and
--6--
1146~61
1 further utilizes the heat from the hydraulic oil system of
the various pumps and motors and is able to create additional
heat from the hydraulic circuits for converting the liquid
to gas, all without danger to the hazardous surroundings of
an oil and gas well.
The present invention, therefore, is well adapted
to carry out the objects and attain the ends and advantages
mentioned as well as others inherent therein. While a pre-
sently preferred embodiment of the invention is given for
the purpose of disclosure, numerous changes in the details
of construction and arrangement of parts may be made which
readily suggest themselves to those skilled in the art and
which are encompassed within the spirit of the invention and
the scope of the appended claims.
