System for applying anhydrous ammonia

A system for applying pressurized anhydrous ammonia to soil. The system includes a tank for containing the pressurized anhydrous ammonia. An anhydrous ammonia meter is in fluid communication with the tank for dispersing controlled amounts of the anhydrous ammonia. A pressurization unit is also in fluid communication with the tank. The pressurization unit defines a pressurization chamber through which anhydrous ammonia from the tank is circulated. A heating system cooperates with the pressurization unit to heat the anhydrous ammonia within the pressurization chamber. The heated anhydrous ammonia is returned from the pressurization chamber to the tank. By adding the heated anhydrous ammonia to the tank, the pressure within the tank is stabilized or even slightly increased.

FIELD OF THE INVENTION 
The present invention relates generally to agricultural devices. More 
particularly, the present invention relates to agricultural devices for 
fertilizing soil through the use of anhydrous ammonia. 
BACKGROUND OF THE INVENTION 
Anhydrous ammonia is a widely used nitrogen based fertilizer. To be used 
effectively for agricultural purposes, it is important for anhydrous 
ammonia to be applied uniformly. It is also important for the anhydrous 
ammonia to be applied as rapidly as possible in order to minimize time and 
labor costs. 
A typical anhydrous ammonia application system includes a tool bar that is 
pulled behind a tractor. A tank of pressurized anhydrous ammonia is 
usually mounted on a wagon coupled to the tool bar. An anhydrous ammonia 
application meter is mounted on the tool bar. The application meter is 
fluidly connected to the tank by a hose. Source pressure within the tank 
forces anhydrous ammonia to flow through the hose from the tank to the 
application meter. The application meter distributes controlled amounts of 
anhydrous ammonia to knives or probes that are mounted on the tool bar. 
The knives project downward from the tool bar and extend into the soil to 
provide a means for injecting the anhydrous ammonia directly into the 
soil. 
Anhydrous ammonia application meters depend on source tank pressure to 
accurately dispense controlled amounts of nitrogen. Cold outside 
temperatures can cause source tank pressures to drop dramatically. 
Consequently, in cold weather situations, operators are at best forced to 
substantially slow down their application of nitrogen. At worst, operators 
are forced to stop fertilizing altogether until their anhydrous ammonia 
supply tanks can be warmed up to increase the tank pressure. 
Preferred fertilization seasons are typically in the spring and fall. 
During these seasons, cold weather is a common occurrence that often 
prevents farmers from efficiently fertilizing their fields. What is needed 
is an anhydrous ammonia application system that is operable in cold 
weather situations. 
SUMMARY OF THE INVENTION 
The present invention relates to a device for dispensing/applying 
pressurized anhydrous ammonia. The device includes a tank containing 
pressurized anhydrous ammonia and an application meter for dispensing 
controlled amounts of anhydrous ammonia from the tank. A pressurization 
unit defines a pressurization chamber that is in fluid communication with 
the tank. A first fluid line directs at least some of the anhydrous 
ammonia from the tank to the pressurization chamber. A heating system 
heats the pressurization unit such that anhydrous ammonia within the 
pressurization chamber is heated and the anhydrous ammonia pressure within 
the pressurization chamber is increased. A second flow line recirculates 
the heated anhydrous ammonia from the pressurization chamber back into the 
tank. 
In use, the above-described device provides a method for maintaining 
anhydrous ammonia pressure within a tank. The method includes the step of 
circulating some of the anhydrous ammonia from the tank through the 
pressurization chamber. The anhydrous ammonia is heated as it circulates 
through the pressurization chamber. Next, the heated anhydrous ammonia is 
returned from the pressurization chamber to the tank where it functions to 
maintain fluid pressure within the tank. 
By constantly supplying the tank with heated anhydrous ammonia, the fluid 
pressure in the tank is maintained despite cold outside temperatures. By 
maintaining pressure in the tank, the anhydrous ammonia meter is able to 
continue applying the proper amounts of anhydrous ammonia. Consequently, 
an operator of the device can continue applying anhydrous ammonia at 
normal rates even in cold temperatures. 
A variety of additional advantages of the invention will be set forth in 
part in the description which follows. Many advantages of the invention 
will be realized and attained by means of the elements and combinations 
particularly pointed out in the claims. In this regard, it is to be 
understood that both the foregoing general description and the following 
detailed description are exemplary and explanatory only and are not 
restrictive of the invention as claimed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Reference will now be made in detail to exemplary embodiments of the 
present invention which are illustrated in the accompanying drawings. 
Wherever possible, the same reference numbers will be used throughout the 
drawings to refer to the same or like parts. 
FIG. 1 shows a diagrammatic view of an exemplary device 20 for 
dispersing/applying pressurized anhydrous ammonia. The device includes a 
tool bar 22 that is coupled to a motive power source such as a tractor 24. 
A tank 26 of pressurized anhydrous ammonia is mounted on a wagon 28 that 
is coupled to the tool bar 22. A first flow line 30 fluidly connects the 
tank 26 to a conventional anhydrous ammonia meter 32. A plurality of 
second flow lines 34 fluidly connect the meter 32 to a plurality of probes 
or knives 36 that are mounted on the tool bar 22. The knives 36 extend 
downward from the tool bar 22 and are oriented to cut into the soil and 
inject anhydrous ammonia therein. 
In operation, a mixture of liquid and vapor anhydrous ammonia flows through 
the first flow line 30 from the tank 26 to the anhydrous ammonia meter 32. 
Tank pressure forces the anhydrous ammonia through the meter 32 and out 
the plurality of second flow lines 34 to the knives 36 which inject the 
anhydrous ammonia into the soil. The application meter 32 relies upon an 
active supply of source tank pressure to insure that the correct amount of 
anhydrous ammonia is being forced through the meter 32 and incorporated 
into the soil by the knives 36. 
The device 20 also includes a system for maintaining anhydrous ammonia 
pressure within the tank 26. As shown in FIG. 1, the system includes a 
pressurization unit 35 defining a pressurization chamber 38. The 
pressurization unit 35 is preferably mounted on a center section of the 
tool bar 22. A third flow line 40 fluidly connects the first flow line 30 
to an inlet side of the pressurization chamber 38. A fourth flow line 42 
fluidly connects an outlet side of the pressurization chamber 38 to the 
tank 26. To maximize the volume of the pressurization chamber 38, the 
pressurization chamber 38 preferably has a cross-sectional area 
substantially larger than the cross-sectional area of the third flow line 
40. 
Anhydrous ammonia is heated within the pressurization chamber 38 by an 
exterior heat source. As shown in FIG. 1, the tractor 24 includes a 
conventional hydraulic system 25, and the heat source comprises warm 
hydraulic fluid from the hydraulic system 25. A fifth flow line 44 carries 
the warm hydraulic fluid from the tractor's hydraulic system 25 to a 
heating chamber 37 (shown in phantom line in FIG. 1) that surrounds the 
pressurization chamber 38. The warm hydraulic fluid circulates through the 
heating chamber 37 thereby transferring heat from the heating chamber 37 
to anhydrous ammonia within the pressurization chamber 38. A sixth flow 
line 46 carries the hydraulic fluid from the heating chamber 37 back to 
the tractor's hydraulic system 25. 
It will be appreciated that hydraulic fluid from the tractor 24 is commonly 
used as a power source for folding the various sections of the tool bar 22 
and for adjusting the wheel heights of the tool bar 22. Consequently, it 
is convenient to use the tractor's hydraulic fluid, which is warmed as it 
performs work, as a source for heating the pressurization chamber 38. 
However, it will be appreciated that in alternative embodiments of the 
present invention, other heating techniques and heat sources can be used 
to heat the pressurization chamber 38. 
In operation, the pressure maintenance system of the device 20 provides a 
method for maintaining anhydrous ammonia pressure within the tank 26 even 
in cold temperatures. In practice, a mixture of liquid and vapor anhydrous 
ammonia is siphoned off the first flow line 30 by the third flow line 40. 
The third flow line 40 carries the anhydrous ammonia mixture to the 
pressurization chamber 38. While in the pressurization chamber 38, the 
anhydrous ammonia is heated by the source of external heat such that the 
liquid anhydrous ammonia is vaporized and the anhydrous ammonia pressure 
within the chamber 38 increases. The heated anhydrous ammonia then exits 
the pressurization chamber 38 through the fourth flow line 42 and is 
carried back to the tank 26. By adding the warm anhydrous ammonia vapor 
back to the supply tank 26, pressure within the tank 26 is stabilized or 
even slightly increased. The stabilized pressure within the tank 26 allows 
an operator of the device 20 to maintain constant ground speed even in 
cold weather. 
It will be appreciated that the flow lines described above typically 
comprise high pressure hose, tubing, piping, or other conventionally know 
conduit for conveying pressurized fluids. 
FIGS. 2 and 3 show an exemplary pressurization unit 50 that is suitable for 
practicing the present invention. The pressurization unit 50 includes an 
inner structure 52 defining a pressurization chamber 54. As shown in FIGS. 
2 and 3, the inner structure 52 preferably comprises a steel pipe having a 
threaded inlet end 53 located opposite from a threaded outlet end 55. 
The pressurization unit 50 also includes a sleeve 56 surrounding the inner 
structure 52. The inner structure 52 and the sleeve 56 together define a 
heating chamber 58 thereinbetween. As shown in FIGS. 2 and 3, the sleeve 
56 preferably comprises an elongated rectangular steel box mounted around 
the inner structure 52. Square steel end plates 60 enclose the ends of the 
sleeve 56. The end plates are welded between the ends of the sleeve 56 and 
the exterior of the inner structure 52. 
The pressurization unit 50 further preferably includes an outer housing 62 
that encloses the pressurization unit 50. As shown in FIGS. 2 and 3, the 
outer housing 62 is an elongated generally rectangular steel box that 
surrounds the sleeve 56. A void 64 is defined between the sleeve 56 and 
the outer housing 62. To maximize the heating efficiency of the 
pressurization unit 50, it is preferred for the void 64 to be filled with 
an insulating material such as foam. Square end plates 66 are welded to 
the ends of the outer housing 62 and to the outer surface of the inner 
structure 52 to enclose the ends of the housing 62. 
The pressurization unit 50 also includes an inlet pipe 68 in fluid 
communication with one end of the heating chamber 58 and an outlet pipe 70 
in fluid communication with the other end of the heating chamber 58. The 
inlet and outlet pipes 68 and 70 extend transversely through the outer 
housing 62 and the sleeve 56 and are preferably welded in place. It is 
preferred for the inlet and outlet pipes 68 and 70 to be located at 
opposite ends of the heating chamber 58 and to extend transversely outward 
from opposite sides of the sleeve 56. 
FIG. 4 is a diagrammatic illustration showing an anhydrous ammonia 
application system 120 incorporating the pressurization unit 50. The 
system 120 includes an anhydrous ammonia tank 122. The tank 122 has a fill 
valve 124 and a withdrawal valve 126. A first flow line 128 fluidly 
connects the withdrawal valve 126 to a relief adapter 130. The relief 
adapter 130 is preferably configured to release excess pressure within the 
first flow line 128. A conventional quick coupler 132 preferably connects 
the first flow line 128 to the relief adapter 130. 
The quick coupler 132 is a safety feature that allows the first flow line 
128 to disconnect from the relief adapter 130 if stress is applied to the 
line 128. The quick coupler 132 automatically closes upon disconnection to 
prevent any anhydrous ammonia from escaping from the system. 
The quick coupler 132 is important because a typical anhydrous ammonia tank 
is mounted on a wagon pulled behind a tool bar. If the wagon accidentally 
uncouples from the tool bar, the quick coupler 132 disconnects from the 
relief adapter and closes the flow line 128. 
A second flow line 134 fluidly connects the relief adapter 130 to an 
anhydrous ammonia application meter 136 for controlling anhydrous ammonia 
distribution to the soil. A third flow line 138 fluidly connects the 
relief adapter 130 to a valve 140 for opening and closing the flow line 
138. The valve 140 is connected to a back check valve 142 by a close 
nipple 144 and a bushing 146. A reducer coupling 148 connects the back 
check valve 142 to the inlet end 53 of the inner structure 52 such that 
the pressurization chamber 54 is in fluid communication with the third 
flow line 138. The back check valve 142 is a one way valve that allows 
anhydrous ammonia to flow through the third flow line 138 into the 
pressurization chamber 54 and prevents anhydrous ammonia from exiting the 
pressurization chamber 54 through the third flow line 138. 
The outlet end 55 of the inner structure 52 is coupled to a T-fitting 154 
by a reducer coupling 156 and a close nipple 158. The T-fitting 154 is 
coupled to a relief adapter 160 for releasing excess pressure from the 
system. The relief adapter 160 is coupled to hydrostat 162 by a bushing 
164. The T-fitting 154 is also coupled to a second back check valve 166 by 
a bushing 168. A fourth flow line 170 fluidly connects the second back 
check valve 166 to an open/close valve 172, preferably equipped with a 
bleeding mechanism, that is coupled to the tank 122. The second back check 
valve 166 is a one-way valve that allows anhydrous ammonia to exit the 
pressurization chamber 54 through the fourth flow line 170 and prevent 
anhydrous ammonia from entering the pressurization chamber 54 through the 
fourth flow line 170. A quick coupler 174 is positioned in line with the 
fourth flow line 170 to provide a safety disconnect if stress is placed on 
the line 170. 
The system 120 also includes a source of heated fluid 176. The source of 
heated fluid 176 circulates heated fluid through the heating chamber 58 
that surrounds the pressurization chamber 54. The heated fluid enters the 
heating chamber 58 through an input line 180 connected to inlet pipe 68 
and exits the heating chamber 58 through an output line 182 connected to 
outlet pipe 70. 
In operation, tank pressure forces a mixture of liquid and vapor anhydrous 
ammonia through the first flow line 128 to the relief adapter 130. At the 
relief adapter 130, some liquid along with some vaporized anhydrous 
ammonia is siphoned into the third flow line 138. The remainder of the 
anhydrous ammonia is directed to the application meter 136 by the second 
flow line 134. 
The anhydrous ammonia in the third flow line 138 flows through the first 
back check valve 142 into the pressurization chamber 54. The first back 
check valve 142 only allows flow in one direction. Consequently, once the 
anhydrous ammonia has entered the pressurization chamber 54, it cannot 
exit the pressurization chamber 54 through the third flow line 138. 
Instead, the anhydrous ammonia is forced to move in one direction from the 
input end of the pressurization chamber 54 toward the output end of the 
pressurization chamber 54. 
While the anhydrous ammonia is within the pressurization chamber 54, it 
draws heat from the heated fluid that is being circulated through the 
heating chamber 58 by the source of heated fluid 176. As the anhydrous 
ammonia is heated, the liquid portion of the anhydrous ammonia is 
vaporized thereby creating higher pressure within the pressurization 
chamber 54. As the pressure within the pressurization chamber 54 
increases, the first back check valve 142 is forced closed and the second 
back check valve 166 is forced open. It will be appreciated that the back 
check valves 142 and 166 are preferably configured to open and close 
concurrently. 
When the second back check valve 166 is forced open, the heated/vaporized 
anhydrous ammonia rushes out of the outlet side of the pressurization 
chamber 54 into the fourth flow line 170. The heated anhydrous ammonia 
travels through the fourth flow line 170 into the source tank 122. It will 
be appreciated that the vaporized/heated anhydrous ammonia continues to 
flow through the further flow line 170 to the tank 122 until the pressure 
in the tank 122 exceeds the pressure in the pressurization chamber 54. 
When the pressure in the tank 122 exceeds the pressure in the chamber 54, 
the second back check valve 166 is forced closed and the first check valve 
142 is forced open causing additional anhydrous ammonia to flow into the 
pressurization chamber 54. By continuously cycling quantities of anhydrous 
ammonia between the pressurization chamber 54 and the source tank 122, 
source tank pressure is maintained or increased. The maintenance of tank 
pressure, even in cold weather improves the operation of the anhydrous 
ammonia application meter 136. 
With regard to the foregoing description, it is to be understood that 
changes may be made in detail, especially in matters of the construction 
materials employed and the shape, size, and arrangement of the parts 
without departing from the scope of the present invention. It is intended 
that the specification and depicted embodiment be considered exemplary 
only, with a true scope and spirit of the invention being indicated by the 
broad meaning of the following claims.