US 3304730 A
Description (OCR text may contain errors)
Feb. 21, 1967 R. B GORHAM DEVICE TO AID PUMPING OF VOLATILE GASES 2 Sheets-Sheet 1 Filed June 9, 1965 INVENI'OR. P08527251 602609 Feb. 21, 1967 R. B. GORHAM 3,304,730
DEVICE TO AID PUMPING 0F VOLATILE GASES Filed June 9, 1965 k w T fi b o 2 Sheets-Sheet 2 m V/iN 1 'OR. P082527 5. 602194 United States Patent Office 3,364,730 Patented Feb. 21, 1967 3,304,730 DEVICE T AID PUMPING 0F VOLATTLE GASES Robert B. Gorham, Mora, Minn. 55051 Filed June 9, 1965, Sell. No. 462,538 4 Claims. (Cl. 6253) This invention relates generally to the transfer of volatile liquids from bulk sources and more particularly to a device for utilizing a portion of the liquid to provide additional pressure to the surface of the liquid such that it may be more easily pumped from a bulk container.
Many homes and other buildings are heated through the use of low pressure gases such as propane and the like. In order to deliver such gases to their point of usage the most economical method available includes the use of bulk tank trucks which carry sufficient amounts of such fuels such that they may service users with a single truck load. The most uneconomical element in this type of delivery system is the time necessary to complete the transfer of the individual homeowners requirement from the bulk tank truck to the house storage tank. The standard method of such transfer is to provide a discharge pump receiving gas in its fluid state from the bulk tank and pumping the same through a hose to the users storage tank.
When dealing with volatile gases a problem arises in the pumping section of the transfer system in that vapor bubbles tend to accumulate within the bulk tank due to the friction head loss in the pumping system. This bubble production may be due to the head loss caused by valves, pipe restriction length or it may be due to the design of the pump itself. A most important problem these vapor bubbles present is that the pump is not pumping up to its full capacity but rather the flow to the pump is diminished and the pump likewise is pumping vapor rather than fluid. Besides causing a lower flow rate than the pump is capable of delivering, this vapor bubble or what is termed cavitation effect also produces unneeded wear on the pump and in actual practice as these vapor bubbles collapse the pumps will tend to knock and operate in otherwise noisy condition which conditions cause the pumps to wear out unduly rapidly.
Many attempts have been made to rectify this bubbling situation but, however, up to this time no satisfactory solution has been achieved.
' It is a purpose of this invention to provide a means and structure for eliminating the cavitation and bubbling problem by providing an additional pressure source acting against the surface of the liquid gas in the tank such that the gas will remain in its liquid state and the formation of these bubbles will be prevented. In order to accomplish this pressure addition to the liquid applicant provides a structure which temporarily utilizes a portion of the liquid and provides a means for vaporizing this portion and applying the additional pressure obtained by such vaporization directly to the surface of the liquid Within the tank.
In order to accomplish vaporization of the liquid and to subsequently use this vapor as pressure against the upper surface of the liquid within the tank, applicant provides a unique vaporizing device which makes use of the available heat created and maintained by the engine of the vehicle provided to haul the bulk tanks. In order to provide the necessary heat to accommodate this vaporization applicant has modified the cooling system of the vehicles engine such that the heat of the usual cooling fluid may be effectively controlled to provide the necessary heat required to vaporize the gas.
Also in order to accomplish the application of vapor pressure to the surface of the liquid, applicant provides a unique distribution system for the portion of the liquid to be vaporized which will be pumped in accordance With the rate at which the bulk liquid gas is being removed from the tank. In this manner the vapor pressure supplied to the liquid surface will be maintained in constant relation to the amount of liquid within the tank and will thus hold the liquid in the tank in equilibrium at all volumes of liquid within the tank.
It is therefore an object of applicants invention to provide a device for vaporizing a portion of the liquid conveyed and carried in a bulk tank system and to use this vaporized gas as an additional pressure head applied directly to the surface of the liquid gas within the tank.
It is a further object of applicants invention to provide means for vaporizing a portion of volatile gas by controlling a heat source readily available with vehicular drawn tank trucks. This heat source being the vehicle engine and thus applicants system eliminates the requirement of any additional heat sources for such vaporization.
It is a further object of applicants invention to provide a safety device which will prevent the accumulation of pressure within a bulk tank system which pressure is created through vaporizing a portion of the liquid gas within the tank which safety system will not permit such vaporization unless a volume of liquid gas is being withdrawn from the tank.
A further object of this invention is to provide a safety device which Will permit the flow of liquid gas only when the pump provided with the bulk tank is in operation thus eliminating the hazard of gas flowing due to a line rupture or the like.
These and other objects and advantages of my invention will more fully appear from the following description made in connection with the accompanying drawings, wherein like reference characters refere to the same or similar parts throughout the several views, and in which:
FIG. 1 is a schematic illustration of the device of applicants invention as applied to a standard bulk gas hauling vehicle;
FIG. 2 is a vertical section taken substantially through the safety device portion included in applicants device;
FIG. 3 is a vertical section taken substantially through the upper core of a vehicle radiator and taken particularly along line 33 of FIG. 1;
FIG. 4 is a vertical section taken substantially through a modified vaporizing chamber provided by applicant.
In accordance with the accompanying drawings, the device of this invention is shown in operating position on a vehicle bulk tank truck as illustrated in FIG. 1 which truck is generally designated T with the ordinarily supplied bulk gas tank designated B. As is common truck T is provided with a radiator R which is included to illustrate the vaporizing operation necessary to accomplish the objects of this invention. The other standard portions of the available systems would of necessity include a pump P having a receiving connection to the bulk tank B which connection is designated 10. Pump P delivers fluid through a discharge conduit 11 which discharge conduit exits through a metering device 12. A shut-off valve 13 is commonly supplied on the discharge conduit 11 such that flow may be controlled therefrom. For delivery to a users tank, a hose is ordidinarily provided on the discharge conduit 11 such that it is not necessary to drive the truck adjacent the users receiving tank but rather it will only be necessary to carry the hose to the receiving tank.
As stated, the difiiculty in using the system as described which includes the bulk tank B, the communicating conduit 10 delivering liquid gas to pump P and communicating conduit 11 for delivery of liquid gas to the users storage tank is the formation of bubbles within the liquid gas such that the pump will operate under conditions of what is known as cavitation and will thus not operate to its highest efliciency. Likewise as stated this cavitation problem causes the pump to operate noisily and this noise is definitely a sign of additional wear on the pump which wear causes the pump to fail much before its expected life span is over.
The inclusions of this standard pumping unit which form the basis of applicants invention and which result in a vapor pressure exerted downwardly upon the liquid surface of the gas within the bulk tank B to eliminate the formation of vapor bubbles within the liquid gas including a conduit 14 connected to and communicating with the discharge conduit 11 exiting from pump P. This conduit 14 is of substantially smaller size than the conduit 11 such that only a portion of the pumped liquid gas will be forced therethrough by the pump. Conduit 14 is shown in connected relation and communicating with a safety sensing device designated S and which will be described hereinafter which safety device is not absolutely essential for the proper installation and operation of applicants device but which is included herein as a safety feature which would be recommended for ordinary useage. It is only necessary to provide conduit 14 to feed into a vaporizing system and for this purpose it would be possible to eliminate the safety device S and to merely extend conduit 14 as shown which extension is designated 14a to a vaporizing unit.
In the form shown this vaporizing unit or coil generally designated 15 is inserted into the top tank of the vehicle engines radiator R and in the form shown the conduit 14a is illustrated entering the top tank of radiator R below the normal surface of the water or coolant therein. Conduit 14a when within the radiator core R includes a plurality of substantially cylindrical convolutes designated 15a which extend laterally across the width of the radiator R and which conduit is then expanded in its cross sectional dimension to approximately double the diameter thereof which increase in size is necessary to permit the vaporization of the liquid gas flowing into the heat area through conduit 14a and this larger size conduit is designated 16. The necessity of larger sized conduit is that the gas in its vapor state will occupy much greater volume than the gas while in its liquid state.
As illustrated in FIG. 3, the larger sized conduit 16 passes several times laterally through the width of the radiator R such that the vapor is actually reheated through its additional exposure to the heat in the radiator R. This larger conduit 16 exits from the radiator core R and is directed into the uppermost portion of the bulk tank B above the normal level of the liquid gas as illustrated in FIG. 1. In its passage as a vapor through conduit 16, the gas passes through a check valve 17 which prevents backward flow of the vapor and the vapor is directed into the tank B where it acts against the upper liquid surface of the liquid gas within the tank.
Applicant has found that it is only necessary to provide a slight additional pressure against the liquid surface of the gas of approximately one to ten pounds and the ideal point of operation in this one to ten pound range is preferably at the three to five pound per square inch level. Application of this pressure serves to hold the volatile gas in equilibrium and therefore this invention is not limited to any particular gas other than gases which may be described as volatile gases that may be held in equilibrium by vapor pressure acting against their surfaces.
In order to necessarily heat the gas and change its state from a liquid to a vapor, applicant has found that it is necessary to remove the normally available thermostat from the vehicles engine and rather to control the engine heat through a standard readily available shutter arrangement designated 18. Such a shutter 18 is commercially available and is operable over the front of the radiator R to limit the passage of air therethrough whereby the temperature of the fluid within the radiator is controlled. Elimination of the thermostat and the inclusion of the shutter 18 device enables the full flow of the cooling agent through the radiator and applicant has found that it is necessary to provide this full flow elevated temperature in order to properly vaporize the liquid gas passed through the coil 15 structure within the radiator core.
With the device supplied as described thus far applicant has found that an application of three to five pounds per square inch of vapor pressure to the surface of the liquid gas within the tank B will permit the pump P to operate near or at its ordinary capacity. Through experimentation with one particular system operating without such vaporizing pressure applicant found that the pump would deliver an average of thirty-two gallons per minute. However, with the vaporizer system as provided by applicant, the pump delivered approximately eighty gallons per minute. This increase, it has been felt, is due to elimination of the cavitation problem in that vapor bubbles are not allowed to form within the bulk tank B when the additional vapor pressure is supplied. Also with the vaporizer system as thus far disclosed, the pump operates at proper load conditions and within a low noise level which tends to satisfy the requirement of eliminating the wear on the pump due to the cavitation problem.
Safety device S previously mentioned consists essentially of a pressure differential valve member. This valve is particularly illustrated in the cross section of FIG. 2 and as shown includes a pair of substantially hemispherical housing members 20-21 with a diaphragm 22 clamped in proper position therebetween to divide the housing compartment into a pair of chambers 23-24. An internal conduit 25 is arranged within compartment 24 and extends inwardly from the outer casing 21 therein to provide a sealing surface 25a normally arranged in closing relation with respect to the diaphragm 22. Conduit 14 is attached to the housing 21 and communicates with the internal chamber 24 therein to supply gas under pressure from pump P. Conduit 14a which as previously stated receives fluid from conduit 14 is connected to the internal conduit 25 and does not ordinarily communicate with the conduit 14 to permit fluid to flow therethrough unless the diaphragm 22 is unseated from the sealing surface 25a.
Within the chamber 23 a balancing spring device designated 26 is arranged in closing relation to diaphragm 22 and is in the form shown a compression spring that will compress under a predetermined load acting thereagainst upward from chamber 24. The position and operation of this spring 26 is to urge the diaphragm 22 into sealing relation with respect to the sealing surface 25a of the conduit 25. A pressure conduit 27 is arranged to communicate with the chamber 23 and the other end of conduit 27 is arranged to pass into the bulk tank B such that the pressure which exists within tank B will likewise be communicated to the housing 23 and cooperate with spring 26 to close the diaphragm 22 against the seating surfaces 25a of the conduit 25. The object of this safety device is to prevent the pumping of liquid through the conduits 14 and 14a and then to the vaporizer coil 15 unless fluid is likewise being pumped under sufiicient pressure through the discharge conduit 11. This structure of course eliminates the possibility of vapor pressure build up within tank B unless liquid gas is likewise being drawn and pumped from the tank B and further eliminates the possibility of liquid gas flowing from the tank B due to a line rupture or the like.
It is necessary with this device to provide continuous vaporization to provide the continuous pressure head on the liquid gas within the tank B as gas is being continually withdrawn from the tank and likewise the vapor supplied to the tank is continually condensing back to its liquid state.
As -a modified vaporization coil applicant provides a device illustrated in FIG. 4 and which is designated in its entirety 30. This coil 30 is provided as a modified insertion feature such that a vaporization coil may be inserted directly into the water hoses of the vehicles engine cooling system and which will eliminate the necessity of removing the top portion of the radiator core to facilitate the insertion of such a vaporizer coil. In this form the coil 30 includes a substantially cylindrical housing 31 having a pair of ends 31a-31b to provide a hollow container and having a pair of connection elements 32-33 provided on the ends 31a-31b to facilitate its insertion thereof into a radiator hose H indicated as being connected on the extending ends 32-33.
The vaporizer coil contained within the chamber 31 is substantially the same as the vaporizer coil described as being inserted into the radiator and consists essentially of the smaller conduit 15a and its convolution connected to and delivering the vaporized gas to the larger conduit 16 which larger conduit passes through the chamber 31 several times to permit the reheating of the vapor before delivering the same to the bulk tank B.
Use of such a coil chamber 30 as stated permits the vaporizer to be inserted directly into a radiator hose of the engine and thus facilitates installing the system into engines and trucks which are presently being used Without requiring their complete revamping.
Although applicant illustrates the liquid gas being fed to the vaporizer as being pumped through the normal discharge pump P, it would of course be possible to provide a completely separate vaporizer unit which could include a separate pump for pumping a portion of gas to be vaporized and which could likewise include an individual heat source other than the vehicles engine for vaporizing this amount of gas.
It should be obvious that applicant has provided a new and unique pressure head device for bulk gas trucks and the like to aid in transferring the gas from the bulk tank.
It will, of course, be understood that various changes may be made in the form, details, arrangements and proportion of parts without departing from the scope of the invention, which generally st-ated consists in the matter set forth in the appended claims.
What is claimed is:
1. Apparatus to provide a pressure head to aid in pumping liquid gas from bulk tanks including:
(a) pump means arranged to receive liquid gas from said tank and deliver the same;
(b) liquid gas vaporizer means for converting liquid gas to vapor;
(c) conduit means extending from said tank discharge to said vaporizer means delivering liquid thereto;
(d) pressure responsive valve means controlling the flow of liquid fluid to said vaporizer;
(e) a vapor conduit receiving vapor from said vaporizer and discharging the same into the bulk tank to create a pressure head above the liquid level therein; and
(f) conduit means communicating with the vapor in the bulk tank and said pressure responsive valve means to permit liquid to flow through said valve means only upon reaching a predetermined discharge pressure from said bulk tank.
2. The structure set forth in claim 1 wherein said pressure responsive valve means includes:
(a) a housing;
(b) means for dividing said housing into a fluid section .and being shiftable within said housing;
(c) a fluid inlet permitting fluid to flow into the fluid portion of said housing;
(d) a fluid outlet communicating with said fluid por tion of said housing;
(e) said housing dividing means controlling communication between said inlet and outlet in response to vapor pressure acting thereagainst whereby the vapor pressure in the bulk tank is controlled by controlling the amount of fluid delivered to said vaporizer.
3. The structure set forth in claim 2 and spring means arranged in said vapor portion of said housing acting against said housing dividing means for normally urging the same into sealing relation between said inlet and outlet but permitting opening thereof when the fluid discharge from said tank reaches a predetermined pressure.
4. The structure set forth in claim 1 and a heat source communicating with the vaporizing means for delivering heat thereto and vaporizing the liquid gas thereto, said vaporizer including a liquid inlet conduit having a predetermined cross sectional area and a discharge conduit having cross sectional area substantially larger than said inlet conduit to facilitate expansion of a ga from a liquid to vapor state.
References Cited by the Examiner UNITED STATES PATENTS 2,308,122 1/1943 St. Clair 62-53 X 2,467,413 4/1949 Wildhack 62-53 X 2,580,710 1/1952 Wildhack 62-53 2,682,154 6/1954 Wilkinson 62-53 X 2,922,289 1/1960 Freeman 62-53 3,048,021 8/1962 Coles et al 62-514 3,127,752 4/1964 Smith 62-52 3,161,234 12/1964 Rannenberg -147 X 3,215,315 11/1965 Graeber et al 62-53 X LLOYD L. KING, Primary Examiner.