US 2764873 A
Description (OCR text may contain errors)
Oct. 2, 1956 w. E. MOOYAART' 2,764,873 METHOD AND APPARATUS FOR FILLING CLOSED CONTAINERS WITH VOLATILE LIQUIDS Filed June 3, 1953 FIG. ]I
WVENTOE WlLLEM E. MD Y A Q 5y 7 7W Hi5 AT TOQNEY Patented Oct. 2, 1956 METHOD AND APPARATUS FOR FILLING CLOSED CONTAINERS WITH VOLATILE LIQUIDS Willem E. Mooyaart, The Hague,
to Shell Development Company, corporation of Delaware Application June 3, 1953, Serial No. 359,255 Claims priority, application Netherlands October 2, 1952 9 Claims. (Cl. 62-1) Netherlands, assignor Emeryville, Calii'l, a
This invention relates to the art of dispensing volatile liquids into closed containers having inlet means for liquid and outlet means for vapor. More particularly, the invention relates to an improved method and apparatus for filling such closed containers with volatile, readily evaporable liquids, such as liquefied hydrocarbons of which propane and butane are examples.
When volatile liquid is admitted into a closed container, the space available within the container for vapor originally present therein and vapor resulting from evaporation of the admitted volatile liquid within the container will decrease progressively as the quantity of liquid within the container increases; consequently, the vapor will be compressed, resulting in a temperature rise in the vapor. A part of this vapor is condensed upon coming into contact with the surface of the liquid within the container and as the heat of condensation resulting therefrom cannot be distributed rapidly enough throughout the entire liquid mass by natural causes, the temperature prevailing at the liquid surface is higher than the temperature of the liquid below such surface. This compression of the vapor and non-uniform temperature distribution have heretofore caused the pressure of the vapor within the container to exceed the vapor pressure of the liquid corresponding to the mean liquid temperature.
Various means have heretofore been proposed to obviate or ameliorate this pressure rise in the vapor space. To permit the vapor to escape to the ambient atmosphere is usually undesirable, not only because such vapors are often hazardous due to their combustibility, but also because of the attendant lossof the valuable materials. The vapor space of the container to be filled is therefore often connected to the vapor space of the reservoir from which the liquid is withdrawn during the filling operation. If, however, the distance separating the reservoir and the container is considerable, this expedient can create difficulties owing to the great length of the connecting vapor conduit; thus, long vapor conduits bring about changes in temperature and present resistance to the passage of the vapor. Moreover it is common practice to install a meter between the supply reservoir and the container to be filled for registering the quantity of liquid dispensed to the container. When vapor is vented to the atmosphere or returned to the reservoir, there results a loss to the customer, who is receiving the liquid in the closed container, of vapors that have already been metered to him, and this makes it necessary to give him an estimate allowance for such losses; such allowances are diflicult to estimate.
It has also been proposed to feed the volatile liquid into the vapor space at the top of the container to be filled instead of into the liquid space at the lower part of the container, so as to insure a better contact and heat transfer between the liquid being introduced and the vapor already present in the container, resulting in a better cooling of the latter, owing to the falling of the introduced liquid through the vapor and onto the liquid surface;
there is then also a slight improvement in the distribution of the heat of condensation to the lower, colder layers of the liquid within the container because of greater turbulence. It has been found in practice, however, that this method does not bring about a sufiicient cooling of the vapor to eliminate the above noted ditlicu-lty and to obviate the need for vapor dischargelines.
Finally, it is already known to draw the vapor out 'of I the vapor space within the container to be filled by means of a mechanically driven gas pump or blower and, after compressing and cooling this vapor, to feed it into the liquid stream flowing into the container. This expedient has a drawback that a special gas pump and power source are required.
It is a general object of this invention to provide an improved method and apparatus for filling closed containers with volatile liquids, whereby the above-m entioned drawbacks are avoided. t
More particularly, it is an object of the invention to provide a method and apparatus of the type described in which the container to be filled neither communicates by a vapor conduit with the reservoir from which the liquid is withdrawn, nor is provided with a vapor outlet or vent through which the vapors are vented to the ambient atmosphere or conducted to an extraneous point of disposal.
According to the invention, which does not requirea return vapor conduit, while losses of vapor are avoided, an eductor, also known. as an ejector, is inserted into the liquid supply conduit,,preferably down-stream from the meter if provided, and a suction side of 'the'eductor is connected to the vapor space of the container to be filled. The volatile liquid is supplied from a source outside of the container at a suitable pressure, for example by a liquid pumpor from an elevated or a pressurized reservoir, and is, prior to discharge into the container, flowed through the eductor as a moving liquid column of substantial velocity in lateral communica-tio-n'with the low pressure zone of the eductor, thereby generating a pressure decrease therein; vapors produced by partial vaporization of the liquid (or of similar liquid previously stored in'the container) are thereby drawn from the container and transferred into said low pressure zone from which they are drawn into the moving column of liquid and thereby intimately mixed therewith, causing complete, direct heat exchange. The resulting mixture is then introduced into the container, thereby progressively increasing the contents thereof. The eductor or ejector, which is activated by the fresh volatile liquid supplied thereto, not only draws in vapor from the vapor space of the container, but also brings about an intimate contact between the vapor and the liquid, so that vapor condenses and/ or dissolves in this liquid and the temperature is almost uniform throughout all parts of the liquid mass within the container.
The invention can be applied both for filling stationary tanks from mobile reservoirs, for example, when filling stationary storage tanks from trucks, as well as for filling tanks mounted upon vehicles, trucks, boats, or the like, or for filling smaller portable vessels, for example, the usual pressure cylinders. I v
The invention will be further described in detail with reference to the accompanying drawing forming a part of this specification, illustrating two specific embodiments by way of illustration, wherein:
Figure 1 is a diagrammatic elevation view of an installation for filling a vehicle-borne container or a truck from a stationary reservoir; and
Figure 2 is a similar View of a part of a modified installation.
Referring'to the drawings in detail, a storage reservoir 1 containing volatile liquid is connected to a liquid pump scribed above. For example,
2 by a supply line 3. A meter 4 may be connected into the pump discharge line 3a which conducts the volatile liquid under moderate pressure to an eductor 5. In the latter, the volatile liquid is discharged from a nozzle 6 which is aligned with and spaced from a convergingdiverging tube 7, and the liquid flows as a moving column in lateral communication with an annular low pressure zone or space 8. The tube 7 discharges into a flexible liquid discharge conduit 9 having a valve 10. The low pressure zone 8 is connected by a flexible suction conduit 11 to a valve 12. The parts described to this point may be parts of a stationary installation.
The container to be filled is shown as a tank 14 mounted I on a truck 15; it has a liquid inlet 16 at the bottom and a vapor outlet opening 17 at the top. These openings communicate with conduits 18 and 19, respectively, having values 20 and 21 and suitable coupling devices 22 and 23 by which they may be connected to the liquid and vapor conduits 9 and 11.
In operation, the eductor is activated by volatile liquid from the reservoir 1 which flows at a substantial velocity from the nozzle 6 into the convergent-divergent tube 7, thereby generating a low pressure in the zone 8 and drawing vapors in the vapor space V of the container 14 through the vapor conduit 19 and open valves 21 and 12. These vapors are drawn in from the low pressure zone 8 into the moving column of volatile liquid and become condensed and/or dissolved in the liquid as a result of the intensive contact therewith within the ejector and the conduits downstream therefrom. This causes direct heat exchange between vapor and liquid. As a result of this action heat of condensation is rapidly distributed throughout the moving liquid and the temperature of the resulting mixture flowing from the eductor is raised. This mixture flows through the open valves and 20 and is introduced into the container 14 through the inlet 16 whereby the liquid contents of the container undergo a gradual temperature rise with a resultant pressure rise, but this pressure rise is considerably lower than that which would occur in the vapor space V if no vapor were discharged therefrom. The entering liquid mixture is slightly warmer than the liquid already in the tank, but the temperature difierence is small. The turbulence and eddy currents naturally resulting tend to reduce the temperature difference. The liquid within the container 14 is thus brought to a more or less uniform temperature, whereby the temperature of the vapors in the space V is lower than it would be if no vapors were withdrawn and the temperature were not equalized. This reduction of the pressure rise in the tank 14. has the advantage that the pump 2 need not act against too high a pressure, while the tank 14 may, if desired, be made of a lighter construction. The pressure at which the liquid is supplied to the eductor 5 need be only slightly in excess of that of the ultimate pressure in the tank 14, although moderately greater pressures will be employed usually to attain a higher rate of de 'very to the container 14.
The quantity of volatile liquid withdrawn from the reservoir 1 is registered by the meter 4. It is evident that all of this material is ultimately delivered into the container 14 with the system described above.
It should be understood that certain changes can be made in the arrangement and disposition of the parts dethe eductor 5 need not be installed as a part of the dispensing system; it could, for example, be carried on a part of the vehicle and a coupling 24 may be provided, by which the delivery line 3a can be connected thereto. Furthermore, the reservoir 1 may be located at an elevation or be maintained under pressure, so that the pump 2 can be omitted.
Moreover, the eductor 5 may be mounted entirely within the container 14, as shown in Figure 2, at any desired level, e. g., at the bottom. The eductor is connected to a vapor pipe 19a, situated entirely within the tank 14 and having vapor intake openings 17a near the top for communication with the vapor space at the top of the tank space into communication with the annular low pressure zone 8 of the eductor. The volatile liquid is delivered from the delivery line 3a which is connected by the coupling 24 to the supply pipe 25 leading to the inlet nozzle of the eductor. The discharge tube 7 of the eductor discharges directly into the tank 14. The operation of this device corresponds in all respects to that previously described, except that the vapor pipe 19a and eductor are entirely within the container 14.
As already stated, the application of the invention is not restricted to the filling of railroad or vehicular tank cars, but can also be used to fill other vessels, both stationary and portable. The invention can also be used to fill vessels of containers with liquids other than the prescribed light hydrocarbons, for example ammonia, carbon dioxide, sulfur dioxide, and the like.
The invention is not restricted to the application of the type of ejector as described before, but any type of gaswithdrawi'ng eductor or ejector may be used.
I claim as my invention:
1. Method of filling a closed container with volatile liquid comprising the steps of: flowing volatile liquid from a source outside said container and prior to discharge into the container at substantial velocity through an eductor and generating a low pressure therein; withdrawing vapors from said container solely by the action of said generated low pressure and transferring said vapors to the eductor, said vapors having substantially the composition of vapor resulting from partial vaporization of said volatile liquid; intimately mixing the transferred vapors with said liquid supplied to the eductor and etfectng direct heat exchange between the vapors and liquid; and progressively increasing the contents of said container by introducing the resulting mixture of liquid and vapor into the container.
2. Method according to claim 1 including in combination therewith the added steps of flowing said volatile liquid prior to flow into the eductor through a metering device for measuring the quantity of said liquid and measuring said quantity of liquid by said device, whereby all of said measured quantity of liquid is delivered to the container.
3. Method of filling a closed container with volatile liquid comprising the steps of: flowing volatile liquid from a source outside said container and prior to discharge into the container as a moving column of substantial velocity in lateral communication with a low pressure zone to generate the low pressure in said zone; drawing from said container vapors resulting from partial vaporization of said liquid and transferring said vapors into said low pressure zone by the action of said generated low pressure; drawing said transferred vapors from said low pressure zone into the moving column, thereby mixing the vapors with the liquid and eifecting direct heat exchange between the liquid and vapor; and progressively increasing the contents of said container by introducing the resulting mixture of liquid and vapors into the container.
4. Apparatus for filling a closed container with volatile liquid comprising, in combination: an eductor having a liquid pressure inlet, a liquid outlet communicating with said container for discharging liquid from the eductor to said container, a low pressure zone, and a suction inlet communicating with said low pressure zone; means for supplying said volatile liquid under pressure from a source outside of the container directly to said liquid pressure inlet; and vapor conduit means interconnecting an upper part of said container and said suction inlet for withdrawing vapors from the container to the low pressure zone by the action of said eductor and mixing said vapors with the liquid flowing through the eductor while progressively increasing the contents of the container.
5. Apparatus according to claim 4 wherein said means for supplying said volatile liquid is provided with a meter for measuring and registering the quantity of volatile liquid supplied to said pressure inlet of the eductor.
6. Apparatus according to claim 4 wherein the eductor is situated externally with respect to said container and the said liquid outlet and the said vapor conduit means are connected to the bottom and top of said container, respectively.
7. Apparatus according to claim 6 wherein said eductor is a part of a dispensing system including a supply reservoir as a part of said means for supplying liquid, said liquid outlet communicates to said container through a liquid conduit having a detachable coupling, and said vapor conduit means includes a conduit having a detachable coupling.
8. Apparatus according to claim 4 wherein the eductor and vapor conduit means are mounted on the container to be filled and the liquid pressure inlet has a detachable coupling connecting said inlet to the means for supplying liquid under pressure.
9. Apparatus according to claim 8 wherein the eductor is situated within the container.
References Cited in the file of this patent UNITED STATES PATENTS Wade Nov. 17, 1936 Melke Jan. 11, 1944 Garretson Nov. 15, 1949 Hansen Nov. 21, 1950 FOREIGN PATENTS Great Britain Oct. 10, 1898