US3469956A - Standby liquefied petroleum gas unit - Google Patents

Description

Sept. 30, 1969 v. H. BROWN STANDBY LIQUEFIED PETROLEUM GAS UNIT 2 Sheets-Shegt 2 Filed June 8, 1966 INVENTOR lr/e A E Own BY WSEcr 'eJ'Z ATTORNEY United States Patent 3,469,956 STANDBY LIQUEFIED PETROLEUM GAS UNIT Verle H. Brown, Seattle, Wash, assignor to E. Sam Dick Co., Inc., Seattle, Wash. Filed June 8, 1966, Ser. No. 556,229 Int. Cl. C10j 1/06 US. Cl. 48-102 5 Claims ABSTRACT OF THE DISCLOSURE Standby unit provides a mixture of air and liquefied petroleum gas to be fed directly into an industrial gas users supply line for use during periods when natural gas supply is cut off in favor of residential users. Th LP gas vaporizer in the unit is partially enclosed within the surge tank which stores the air-gas mixture, to provide heat transfer from the vaporizer to the stored mixture and thereby maintain it in a vaporized state without necessity for a separate heat source for the surge tank itself.

This invention is for a liquefied petroleum gas unit which is normally maintained on a standby basis and which may b placed in operation in a short time.

As is well known, an industrial user of natural gas during a shortage of natural gas must allow the residential user first use of available natural gas. If there be no available natural gas, then the industrial user cannot use natural gas and either must cease using gas or use gas in a standby unit. For example, on a cold day residential users and industrial users of natural gas may use more than what they normally use on a day having a temperature a few degrees higher. The capacity of the natural gas system is not sutficient to supply both the residential user and the industrial user. Therefore, it is necessary for the industrial user to lessen the use of natural gas or to cease using the natural gas. In order to continue to operate in such a situation an industrial user will normally have a standby liquefied petroleum gas unit. Ordinarily, the petroleum gas is not compatible with natural gas and it is necessary to mix the petroleum gas with air to form a petroleum gas and air gaseous mixture. When the industrial user is notified that natural gas will no longer be available to him, the industrial user may have approximately three hours advance notice. Prior equipment which has been used by industrial users in such situations has comprised a storage tank for storing liquefied petroleum gas and also a storage tank for storing the petroleum gas and air gaseous mixture. On cold days the petroleum gas in the petroleum gas and ai gaseous mixture has had a tendency to freeze to form liquified petroleum gas. This has left a mixture rich in air and which mixture does not burn properly. To prevent the petroleum gas in the petroleum gas and air gaseous mixture from freezing and separating there has been provided external heating means in the storage tank for the petroleum gas and air gaseous mixture. Such heating means has tended to increase the initial cost of the equipment and also has tended to increase the cost for maintaining a gaseous mixture of petroleum gas and air.

With this background and having worked with natural gas and petroleum gas, I have invented a standby liquefied petroleum gas unit having as an object the provision of such a unit which can rapidly be placed in use on short notice; to provide such a unit which can be placed in use with relatively no effort; to provide such a unit which is clean in operation and does not produce smudge in the air and does not have a strong odor; to provide such a unit which uses the same piping as natural gas; to provide such a unit which in itself has no moving parts; to provide such a unit which has positive action in cold weather and does not allow petroleum gas in the petroleum gas and air gaseous mixture to freeze and separate from the mixture; to provide such a unit which is a small compact unit for its capacity; to provide such a unit which can b inconspicuously placed in an industrial area and, in certain circumstances, can be substantially hidden from view; to provide such a unit which is attractive in appearance; to provide such a unit whose mounting and Support is simple in construction and easy to erect; to provide such a unit which is a complete package in itself; to provide such a unit which is inexpensive and which makes it possible to ship the complete assembled unit; to provide such a unit which is small in the volume it occupies and yet has the same capacity as larger standby liquefied petroleum gas units; to provide such a unit which is economical in a small installation; to provide such a unit which has no external heating means for maintaining the petroleum gas in a vapor phase in the petroleum gas and air gaseous mixture and does not require steam tracing or jacketing on the surge tank; to provide such unit which can readily produce a substantially constant ratio of air to petroleum gas in the gaseous mixture; and, to provide such unit which has a wide range of flow rate of a substantially constant ratio of air to petroleum gas in the petroleum gas and air gaseous mixture.

These and other important objects and advantages of the invention will be brought forth upon reference to the accompanying drawings, the detailed disclosure of the invention and the appended claims.

In the drawings:

FIGURE 1 is a side elevational view of the standby liquefied petroleum gas unit and illustrates the structure of such unit; and

FIG. 2, on an enlarged scale, is a fragmentary vertical cross-sectional view illustrating the internal structure of the vaporizer of the standby liquefied petroleum gas unit, without the insulation jackets shown in FIG. 1.

In FIG. 1 there is illustrated a standby liquefied petroleum gas unit 10. Such a unit 10 may be considered to comprise three separate units, namely the vaporizer 12, a mixer 14, and a surge tank 16.

The surge tank 16 is illustrated in FIG. 1. The central portion of this surge tank may b considered to comprise a circular band while the upper or top portion and the lower or bottom portion may be considered to be in the configuration of an ellipsoid. The surge tank 16 may be of these three separate portions and which portions are welded to form the tank proper. In the bottom it is seen that there is an adapter 18 and a tank drain 20 having a valve.

Near one side of the surge tank 16, see FIG. 2, there is an opening 22 in the lower eliptical portion and an opening 24 in the upper eliptical portion. In the openings 22 and 24 there is positioned the vaporizer 12.

The vaporizer 12 is an upright housing in the configuration of an upright circular cylinder and has a lower portion 26 and an upper portion 28. The lower portion 26 connects with a foot 29. Near the bottom of the lower portion 26 there is a plate 30 which seals off the lower portion 26. Above the plate 30 there is an opening 32 in the wall 26. An adapter or fitting 34 is welded to the outside wall 26 so as to connect with the opening 32. As is seen in FIG. 2 the lower end or plate 30 is welded to the inside of the housing of 26. Above the plate 30 there is welded a plate 36. In the plate 36 there are numerous openings 38. The plates 30 and 36, in conjunction with the walls of the lower portion 26, define a chamber 40. The chamber 40 may he referred to as a steam chamber.

In the wall 26 directly above the plate 36 there is an an opening 42. A pipe 44 is welded to the outside of the wall 26 and connects with this opening 42. Further, above the plate 36 and in the wall 26 is an opening 46. A pipe 48 is welded to the outside of the wall 26 and connects with the opening 46. On the outside of the lower portion 26 there is welded circular flange 50. This circular flange 50 has a number of passageways 52. Positioned on top of the circular flange 50 is a plate or divider 54 having a number of passageways or opening 56 therein.

On the lower part or lower end of the upper section 28 there is welded a flange 58 having a number of passageways 60 therein. Tie rods 62 and nuts 64 connect together the flanges 50 and 58 so as to squeeze the plate 54 between the upper part of the lower section 26 and the lower part of the upper section 28. The volume defined by the plate 36, the plate 54, and the walls of the lower section 26 may be considered to be a condensation chamber 66. Onto the pipe 48 there is attached a pressure gauge 49. Steam is introduced into the steam chamber 40 through pipe 34 and opening 32. The opening 42 and pipe 44 are where some of the condensate in the condensation chamber 66 is removed.

In FIG. 2 it is seen that in the openings 38 in the plate 36 there are positioned the lower end of pipes 70. The pipes 70 project through the openings 56 in the plate 54 and well up into the upper section 28 of the vaporizer 12. In the openings 56 in the plate 54 there are pipes or tubes 72. The tubes 72 are of a larger internal diameter than the external diameter of the pipes 70. In fact, the tubes 72 may be considered to be circular housings for the upper part of the pipes 70. In FIG. 2 it is seen that the upper part of the tubes or housing 72 are sealed or closed. Also, in FIG. 2 it is seen that the ends of the pipes 70 are open so that with the lower ends of the pipes 70 in the steam chamber 40 it is possible for the steam chamber 40 to connect with condensation chamber 66 by means of the pipes 70 and the housing 72. The purpose is readily seen as steam may enter into the steam chamber 40 and flow through the pipes 70 and into the housing 72. The condensation may flow down the interior of the housings 72 and into the condensation chamber 66.

In the lower part of the upper section 28 and in the wall of the upper section 28 there is an opening 74. Pipe 76 is welded to the outer surface of the wall of a section 28 and in alignment with the opening 74. Further, in part of the upper section 28 there is an opening 78 in the wall and a pipe 80 is welded to the outer surface of the wall so that the pipe 80 is in alignment with the opening 78. Slightly above the opening 78 there is an opening 82. A pipe 84 is welded to the outer surface of the wall of the section 28 and in alignment with the opening 82. Above the opening 82 there is an opening 86 in the wall of section 28 and a pipe 88 is welded to the outer surface of the wall with the pipe in alignment with opening 86. Finally, on top of the housing or the upper section 28 there is an opening 90.

In an installation in which there are two mixers 14 there are two openings 86 and two pipes 88, at approximately 180 angle with each other.

In FIG. 1 it is seen that strainer 94 connects with a four-way cross 96. One end of the strainer 94 connects with a source of liquefied petroleum gas (not shown). The four-way cross 96 connects with a valve 98 which in turn connects with piping 100. The piping 100 connects with a normally closed solenoid valve 102. The valve 102 connects with piping 104. The piping 104 connects with a T 106. The T 106 connects with suitable piping 108. The piping 108 connects with pipe 76 so as to introduce liquefied petroleum gas into the upper section 28 of the vaporizer 12. The T 106 also connects with piping 110. The piping 110 connects with a T 112. The T 112 by means of piping 114 connects with a one-way back-flow check valve 116. The check valve 116 connects with piping 118 and relieves excess pressure from the vaporizer back to the supply tank when the solenoid valve 102 is 4 closed. The T 112 also connects with the valve 120. The valve 120 by means of piping 122 connects with the fourway cross 96 and provides a path for supply of gas to the vaporizer if the solenoid valve is not working or is being replaced. The normally closed solenoid valve 102 is electrically connected by a wire 126 enclosed in a conduit 124 to a suitable transducer contained within adapter 128 and pipe 80. After the system has been turned on by an electrical signal at input switch 129, opening solenoid valve 102, the transducer provides a signal for safety purposes to close the solenoid valve when the liquid level in the vaporizer 12 exceeds a predetermined amount.

The liquefied petroleum gas is introduced through the strainer 94 to the four-way cross 96 and into the upper section 28 of the vaporizer 12 through solenoid valve 102 and piping 104. As the vapor pressure in the vaporizer builds up, some of the liquid gas may be forced back into the supply line through the open solenoid valve 102 to equalize the pressure. When more gas is required by the system upon withdrawal of air-gas mixture from the surge tank, then more gas will enter the vaporizer as the pressure therein drops below the supply line pressure.

In the pipe 84 there is placed a gauge 130 and which gauge is a presure gauge for the liquefied petroleum gas and may read from 0 to 300 pounds pressure. In FIG. 1 it is seen that on the side of the vaporizer that there is a gauge 132. This is the steam temperature gauge which may read temperature from approximately 50-400 P. On the pipe 92 there is a relief valve stack 134 which constitutes a second safety device in addition to the shutoff control by the transducer in adapter 128, operative in case the pressure becomes too great in the vaporizer.

A vapor pressure regulator 136 connects with the pipe 88. This vapor pressure regulator regulates the pressure of the vaporized petroleum gas supplied through flexible tube or pipe 138 to the normally closed solenoid valve 140. The normally closed solenoid valve 140 by means of piping 142 connects with a T 144. On the T 144 is a orifice pressure gauge 146 which may read approximately 0-60 pounds per square inch in orifice pressure. The T 144 connects with a T 148. The T 148 connects with an air inlet adapter 150 and a venturi tube 152 which together comprise the mixer 14. The vaporized petroleum gas in passing through the venturi tube 152 creates a vacuum or a decreased pressure so that air enters the venturi tube through the air adapter 150 and mixes with the vaporized petroleum gas to form the petroleum gas and air gaseous mixture.

In the upper portion of the surge tank 16 there is an adapter 154 which leads into the interior of the surge tank 16. The venturi tube 152 by means of a pipe 156 connects with a valve 158. The valve 158 by means of pipe 160 connects with the adapter 154. In this manner, with the opening of the valve 158, the petroleum gas and air gaseous mixture flow into the interior of the surge tank 16. Again, it is seen that on top of the surge tank 16 that there is an adapter 162. This adapter 162 connects with the manual shut-off valve 164. The valve 164 by means of piping 166 connects with a valve 168, which is part of a regulator 170. The regulator 170 is an optional regulator for the petroleum gas and air gaseous mixture so as to regulate the pressure within a range of approximately 0-10 pounds per square inch pressure when required by low customer supply line pressure. A suitable connecting means (not shown) is coupled with the outlet of valve 168 in the installation to convey the petroleum gas and air gaseous mixture to the place of usage.

A pressure control sensor unit 171 positioned centrally in the top of the surge tank senses the pressure therein and operates the solenoid valve 140 through suitable electrical connections 173 and 175. The gas vapor provided through regulator 136 is thus supplied to the mixer 14 by operation of solenoid valve 140 when the surge tank pressure drops below a predetermined value and is shut off when the mixture supplied to the tank causes the pressure to reach a second, higher value. The demand for the air-gas mixture from the surge tank is determined by the pressure in the customer supply line coupled to regulator valve 168.

On top of the surge tank 16 it is seen that a relief stack 172 may be positioned.

In operation the following procedure is followed. When the operator has been notified that natural gas is no longer available, then steam is introduced through the pipe 34 and the opening 32 into the steam chamber 40. Also, the normally closed solenoid valve 102 is opened automatically when the system is switched on and liquified petroleum gas is introduced into the upper section 28 of the vaporizer 12. The steam flows upwardly through the pipes 70 and into the housings 72. The liquefied petroleum gas contacts the outside of the housings 72 and heat energy is transferred from the steam inside the housings 72 to the liquefied petroleum gas on the outside of the housings 72. The liquefied petroleum gas is vaporized and most of the steam is condensed and flows downwardly around the pipes 70 into the condensation chamber 66. The vaporized petroleum gas flows out through the pipes 88, through the flexible pipe 138, through the open solenoid valve 140 and to the T 148 and the venturi tube 152. Air flows into the venturi tube 152 and is mixed with the vaporized petroleum gas to form the petroleum gas and air gaseous mixture which flows through the adapter 154 into the surge tank 16. Inside the surge tank 16 petroleum gas and air gaseous mixture is in contact with the upper section 28 of the vaporizer 12. The temperature of the upper section 28 and the temperature inside the surge tank 16 may be the same or the temperature of the upper section 28 may be somewhat higher than the temperature inside the surge tank 16. By having the upper section 28 inside the surge tank 16, the upper section 28 functions as a heat exchanger for transferring heat energy from the upper section 28 to the contents inside the surge tank 16. In this manner, the petroleum gas in the petroleum gas and air gaseous mixture will not condense to form liquefied petroleum gas and air above the liquefied petroleum gas in the bottom of the urge tank 16. In other words, it is not necessary to have external heating means for maintaining the petroleum gas in a vapor form inside the surge tank 16 as the upper section 28 performs this function. It is seen that the surge tank 16 is supported by a leg 174 (actually, there is another leg on the other side so that there are two legs 174 supporting surge tank 16). In addition to the two legs 174 the vaporizer 12 functions as a leg to support the surge tank 16. There may be an insulation jacket 176 (not shown in FIG. 2) around the lower section 26 of the vaporizer 12. Further, there may be insulation 178 around the lower part of the upper section 28 before the vaporizer 12 goes into the interior of the surge tank 16. Further, there may be an insulation jacket 180 around the upper part of the upper section 28 of the vaporizer 12.

The steam being introduced into the steam chamber 40 may be at a temperature of approximately 270 F. The liquefied petroleum gas is a mxiture of propane and butane. Normally, the petroleum gas and air gaseous mixture comprises approximately 45% air and 55% petroleum gas by volume and has a heating value of about 1,450 B.t.u. per cubic foot and a specific gravity of about 1.3. The temperature of the gaseous mixture inside the surge tank 16 may vary in the range of approximately 150-250 F., largely dependent upon the temperature outside the surge tank 16. The heat is transferred from the upper section 28 of the vaporizer 12 to the contents of the surge tank 16 by radiant energy; by conduction from the petroleum gas and air gaseous mixture contacting the walls of the upper section 28; and, also by convection. Of utmost importance is that fact that heat is transferred to the total gas and air gaseous mixture inside the surge tank 16 so as to maintain the petroleum gas in a vaporized state. Unit such as the unit which has been described can be designed having production capacities of from 6,000,000 to 64,000,000 B.t.u.s per hour and more.

From the foregoing it is seen that I have provided a compact standby liquefied petroleum gas unit which can be assembled and packaged in a plant and shipped as an assembled and packaged unit to the user. Further, the design is such that it may be placed. close to the users plant and out in the open. Or, it may be placed behind shrubbery and the like because of its small size and therefore can readily be hidden from view.

Having presented my invention, what I claim is:

1. A standby liquified petroleum gas unit comprising:

(a) a surge tank;

(b) a vaporizer for vaporizing liquefied petroleum gas for storage in said tank; and,

(c) said vaporizer being partially in said tank.

2. A standby liquefied petroleum gas unit according to claim 1 and comprising said vaporizer being a support for said surge tank.

3. A standby liquefied petroleum gas unit according to claim 1 and comprising:

(a) a mixer for mixing the petroleum gas and air to form a petroleum gas and air mixture;

(b) said mixer connecting with said vaporizer; and,

(c) said mixer connecting with said surge tank.

4. A standby liquefied petroleum gas unit, said unit comprising:

(a) a surge tank;

(b) a vaporizer for vaporizing liquefied petroleum gas;

(c) said vaporizer being an upright vaporizer;

.(d) said vaporizer being partially in said surge tank so as to be able to transmit heat energy to the contents inside surge tank;

(e) said vaporizer comprising heat transfer means;

(f) said vaporizer comprising a chamber housing said heat transfer means;

(g) an inlet to said chamber for introducing liquefied petroleum gas into said chamber;

(h) an outlet for said chamber to allow vaporized petroleum gas to leave said chamber; and,

(i) said outlet connecting with said surge tank.

5. A standby liquefied petroleum gas unit according to claim 4 and comprising:

(a) said heat transfer means comprising upright pipes for heated vapor;

(b) a mixer for mixing vaporized petroleum gas and air to form a gas and air mixture;

(c) said mixer connecting with said vaporizer;

((1) said mixer connecting with said surge tank; and,

(c) said mixer comprising an orifice for mixing the petroleum gas and air.

References Cited UNITED STATES PATENTS 2,351,131 11/1940 Kerr 62-52 XR 3,285,719 ll/1966 Bodle et a1. 6251 XR 2,609,282 9/1952 Haug et a1 48196 XR 1,889,162 11/1932 Thomas et a1 62-52 XR MORRIS O. WOLK, Primary Examiner J. D. OLSEN, Assistant Examiner U.S. C1. X.R.

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