US3578753A

US3578753A - Liquefied petroleum vaporizer with automatic vaporizer bypass

Info

Publication number: US3578753A
Authority: US
Inventors: William P Freeman
Original assignee: Individual
Current assignee: John E Mitchell Co
Priority date: 1969-02-28
Filing date: 1969-02-28
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: CA936118A

Abstract

A liquid petroleum vaporizer with means to supply vapor from a storage tank under conditions of demand in excess of the capacity of the vaporizer and with an automatically operable valvecontrolled line bypassing the vaporizer when the vapor in the storage tank is adequate to supply the demand.

Description

United States Patent [54] LIQUEFIED PETROLEUM VAPORIZER WITH AUTOMATIC VAPORIZER BYPASS 6 Claims 5 Drawing Flgs' ABSTRACT: A liquid petroleum vaporizer with means to US. Cl 62/51, supply vapor from a storage tank under conditions of demand 62/52 in excess of the capacity of the vaporizer and with an auto- Int. Cl Fl7c 9/02 matically operable valve-controlled line bypassing the Field of Search 62/51, 50, vaporizer when the vapor in the storage tank is adequate to 52 supply the demand.

PRESSURE vAPoI? L NE g @EsPO/VS/ 145' VA L \/E 23 V M 22 7 k 33 38 BACK PRESSURE STORAGE 40 CHECK VAL v5 22 TANK 2 5 41 16 26 k/ stjfftgs FLOW 7 6A5 REGULATOR T 7 V ,M L/OU/D L nvs VA P OR I 2 ER Primary ExaminerAlbert W. Davis, Jr. Attorney-Kingsland, Rogers, Ezell, Eilers and Robbins 10 5 THEIEMOSTATIC.

CONTROL. VA LVE LIQUEFIED PETROLEUM VAPORIZER WITH AUTOMATIC VAPORIZER BYPASS BRIEF DESCRIPTION OF THE INVENTION In the system of this invention, a vaporizer receives liquid petroleum from a storage tank. The petroleum in the vaporizer is heated to produce vapor and the vapor from the vaporizer is delivered to a demand area. The vaporizer has a float-controlled valve. One of the inputs to the valve is connected by a pipe to the upper side of the petroleum tank. The other input to the valve comes from the vaporizer. When the demand for vapor does not exceed the capacity of the vaporizer to supply vapor, the float-controlled valve closes the auxiliary supply line leading from the upper end of the storage tank. When the demand for vapor increases above the capacity of the vaporizer to supply vapor, the reduced pressure within the vaporizer causes the liquid level therein to rise, raising the float and opening the valve to admit auxiliary vapor from the storage tank. If the demand for vapor is so high that the ability of the vaporizer to supply vapor is exhausted, the float rises still higher and completely blocks the supply of vapor from the vaporizer, leaving the valve open to the pipe supplying vapor from the storage tank. The foregoing kind of vaporizer system is generally set forth in Mitchell, et al. US. Pat. No. 2,551,501.

This invention adds a bypass pipe leading directly from the storage tank to the demand area. A pressure compensating valve operates in response to pressure within the storage tank to control the flow of vapor through the bypass line. The pressure compensating valve is set to cause vapor from the storage tank to bypass the vaporizer and flow directly to the demand area when the pressure compensating valve senses that the corresponding storage tank pressure is at or above a predetermined value because, at sufficiently high ambient temperatures and/or sufficiently low demand, the petroleum within the storage tank will boil and generate enough vapor to supply the demand. When the demand for vapor increases or the ambient temperature drops below a level at which the petroleum in the storage tank will boil at a sufficient rate to supply enough vapor, the pressure compensating valve senses the corresponding reduced pressure and blocks the flow of vapor through the line bypassing the vaporizer. With the bypass line blocked, vapor within the capacity of the vaporizer is supplied to the demand area and, if the demand for vapor exceeds the capacity of the vaporizer to supply vapor, the surplus flow valve opens to permit auxiliary vapor to be supplied from the storage tank.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of the control system.

FIG. 2 is an enlarged elevation view in vertical section through the vaporizer.

FIG. 3 is a further enlarged view in vertical section of the surplus flow valve.

FIG. 4 is a view in section taken along the line 4-4 of FIG. 3.

FIG. 5 is a schematic diagram of a modification of the control system.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the control system includes a large petroleum tank 11 and a vaporizer 12. A pipe 13 is connected from the lower side of the storage tank 11 through the wall 14 of the vaporizer 12 to deliver liquid petroleum into the lower end of the vaporizer 12. There is a shutoff valve 15 in the pipe 13. Although not shown, the vaporizer 12 also has the conventional burner and pilot that use vapor from the storage tank 11 as fuel, with the burner being controlled by a thermostat, all as conventional in the art.

As described in the aforesaid Mitchell, et al. patent, a surplus flow valve 16 is mounted at the upper end of the vaporizer 12. The surplus flow valve 16 has a valve housing 17. As shown in FIG. 3, one inlet passage 18 in the valve housing 17 leads from the vaporizer 12 to a valve seat 19. Another inlet passage 20 leads to another valve seat 21 spaced from the valve seat 19. A suitable pipe 22 connects the inlet passage 20 to the upper end of the storage tank 11. There is a manually controlled shutoff valve 23 in the pipe 22. An outlet passage 24 is located between the

valve seats

19 and 21. A pipe 25 leads from the outlet passage 24 through a gas pressure regulator 26 to the demand area which comprises appliances and the like.

A float 28 is positioned within the housing 14 of the vaporizer 12. The float 28 is guided for vertical movement by a vertical pin 29 that can reciprocate within an opening 30 in a guide 31 welded to the bottom inner surface of the housing 14. A rod 32 extends upwardly from the top of the float. A valve member 33 is mounted on the rod 32 for movement toward and away from the valve seat 19. Another valve member 34 is mounted on the upper end of a thin rod 35 that extends upwardly from the center of the valve member 33. As the rod 32 moves up and down, the valve member 34 moves away from and toward the valve seat 21 and the valve member 33 moves toward and away from the valve seat 19. There are grooves 36 in the sidewall of the inlet passage 20 to assure the free flow of vapor past the valve member 34 when the valve member 34 is above the valve seat 21.

For the control system of this invention, a pipe 38 is connected between the pipe 22 that leads from the upper end of the storage tank 11 and the pipe 25 that leads from the outlet chamber 24 of the surplus flow valve 16. A pressure responsive control valve 39 is mounted in the pipe 38. The pressure responsive control valve 39 is of a conventional design and is connected to operate in response to vapor pressure in the upper end of the storage tank 11. The valve 39 is set to remain closed so long as the vapor within the storage tank 11 is below a predetermined value and to open when the vapor pressure within the storage tank 11 reaches or exceeds the predetermined value. For example, when the petroleum in the storage tank 11 is propane, the pressure responsive control valve 39 may be set to open when it senses a pressure within the storage tank of 20 p.s.i.g. or higher. A manual shutoff valve 40 is mounted in the pipe 38 downstream of the pressure responsive control valve 39.

A back pressure check valve 41 is mounted in the pipe 25 between the surplus flow valve 16 and the juncture between the pipe 25 and the pipe 38. The back pressure check valve 4-1 is of a conventional design of the type that produces a pressure drop, preferably of about 3 p.s.i., in vapor flowing through the valve 41. When the vapor from the storage tank 11 has this free path through the bypass pipe 38 to the demand area, the pressure within the vaporizer 12 can build up to such an extent that all the liquid is forced from the vaporizer 12 back to the storage tank 11, deactivating the vaporizer 12 in the usual manner, such as by a thermostatic control value 50 that temporarily turns off the burner 51. The back pressure check valve 41 in the pipe 25 downstream of the surplus flow valve 16 assures that, as long as vapor can flow through the pipe 38, a back pressure will be maintained to impede the flow of vapor from the vaporizer and permit the pressure in the vaporizer to build up and produce a shutting off of the vaporizer.

A modified control system 45 is shown in FIG. 5. In this modified control system 45, most of the components and connections are the same as described for the control system 10 shown in FIG. 1, and for these identical components and connections, identical reference characters have been used. In this modified control system, a pressure responsive control valve 46 is connected in the pipe 25 between the surplus flow valve 16 and the juncture between the pipe 25 and the pipe 38. The pressure responsive control valve 46 is also connected to respond to vapor pressure within the storage tank 11. However, as distinguished from the pressure responsive control valve 39 of the system shown in FIG. I, the pressure responsive control valve 46 is designed to close when the pressure of vapor within the storage tank 11 reaches or exceeds a predetermined value and to open when the pressure of vapor within the storage tank 11 drops below the predetermined value. Again, if the petroleum within the storage tank is vapor, the pressure responsive control valve 46 may be set to close at a sensed pressure of 20 p.s.i.g.

A back pressure check valve 47 is connected in the pipe 38. The back pressure check valve 47 is of a conventional design that imparts a pressure drop of about 3 psi. to vapor flowing through it.

OPERATION The control system can be made operable by opening the manually controlled

shutoff valves

15, 23 and 40. Assuming the vapor pressure within the tank 11 is below 20 p.s.i.g. and the pressure responsive control valve 39 of FIG. 1 is therefore closed, the thermostat will cause the vaporizer burner (not shown) to burn to boil liquid within the vaporizer 12. With low pressure in the vaporizer l2, liquid petroleum can flow from v from rising above a normal level. Hence, the float 28 will remain in a normal suspended position that holds the valve member 33 below the valve seat 19 and holds the valve member 34 in contact with the valve seat 21. Since the valve member 34 is in contact with the valve seat 21, no vapor can flow from the pipe 22 past the valve seat 21. Vapor is supplied from the vaporizer 12 by flowing through the inlet passage 18 in the surplus flow valve 16, past the valve seat 19, through the outlet passage 24, the pipe 25,, the back pressure check valve 41, and the gas pressure regulator 26, on to the demand area.

If the demand for vapor is reduced, so that vapor is produced in the vaporizer 12 at a greater rate than is being drawn off by the demand area, the vapor pressure within the vaporizer housing 14 will rise. This rise in vapor pressure will force the liquid level within the vaporizer 12 down, returning some liquid petroleum to the storage tank 11. This reduces the amount of liquid in the hot areas of the vaporizer housing 14 and reduces the rate of boiling of the petroleum and therefore the rate of production of the vapor. In this manner, the vaporizer 12 tends to produce vapor at a rate corresponding with the rate of demand for vapor.

If the rate of vapor delivered to the demand area increases because of increasing demand for vapor, a greater rate of vapor will be withdrawn from the vaporizer housing 14, reducing the pressure of vapor within the vaporizer housing 14. This permits more liquid petroleum to flow from the storage tank 11 into the vaporizer 12, resulting in raising the level of liquid within the vaporizer 12 and increasing the amount of liquid in the hot area of the vaporizer housing 14. The result is an increase in the rate of boiling of the petroleum to respond to the greater demand rate for vapor.

During the normal variations in liquid level within the vaporizer 12, the float 28 simply hangs from the stem 32 as the valve member 34 is seated against the valve seat 21. Therefore, for normal variations in vapor demand within the capacity of the vaporizer 12 to supply vapor to meet that demand, no flow of vapor can take place past the valve seat 21. However, if the demand for vapor exceeds the capacity of the vaporizer to generate vapor, the pressure of the vapor within the vaporizer housing 14 will continue to fall until the level of liquid within the vaporizer rises to raise the float 28 and lift the valve member 34 from the valve seat 21. This permits auxiliary vapor to flow from the upper end of the storage tank 11 past the valve seat 21 to the outlet passage 24 for mixture with vapor being supplied from the vaporizer 12. If the demand for vapor becomes very high, the liquid level within the vaporizer housing 14 will rise still further until the valve member 33 seats against the valve seat 19, completely blocking the flow of vapor from the vaporizer 12. Then, all the vapor is supplied from the storage tank 11. Of course, as soon as the valve member 33 seats against the valve seat 19, the vaporizer 12 can rapidly build up vapor within the vaporizer housing 14, reestablishing the ability of the vaporizer 12 to supply vapor. Hence, the increased pressure within the vaporizer 12 will again force liquid from the vaporizer, lowering the float 28, and dropping the valve member 33 from the valve seat 19.

The foregoing operation can take place so long as the pressure responsive control valve 39 is closed. However, on warm days when the petroleum within the storage tank 11 boils more readily and creates more vapor, thereby increasingthe pressure within the storage tank 11, or during times of relatively low demand for vapor by the demand area so that the rate of withdrawal of vapor is quite low and the storage tank 11 can maintain a relatively high pressure, the valve 39 may open. The valve 39 is set to respond to the pressure variations within the storage tank 11 and to open whenever the pressure within the tank 11 reaches or exceeds the set pressure for the valve 39. If the valve 39 is set to open upon sensing a pressure of 20 p.s.i.g., for example, and if the pressure within the storage tank 11 reaches or exceeds 20 p.s.i.g., the valve 39 will permit vapor to flow directly from the storage tank 11 through the pipe 22, to the pipe 38, and through the now open pressure responsive control valve 39 to the pipe 25, through the gas pressure regulator 26, and on to the demand area.

If the demand for vapor increases, or if the temperature drops so that less boiling of petroleum in the storage tank 11 occurs, or if any other factor occurs which reduces the vapor pressure within the storage tank 11 to a value below 20 p.s.i.g., the pressure responsive control valve 39 closes. This blocks further flow of vapor from the storage tank 11 through the bypass pipe 38 and reestablishes the functions and operations of the vaporizer 12 to supply vapor, perhaps with auxiliary vapor to be supplied from the upper end of the storage tank 11, all as already described. Thus, the provision of the bypass pipe 38, the pressure responsive control valve 39 and the back pressure check valve 41, permit the supplying of vapor directly from the storage tank 11 when conditions so permit, resulting in a saving of such loss of petroleum as is required for operation of the vaporizer 12. Under conditions when the storage tank 11 cannot supply the demands of the demand area, such as when the ambient temperature will not boil the petroleum within the storage tank 11 rapidly enough, or when the demand for vapor increases, the pressure responsive valve 39 automatically closes and the vaporizer 12 is automatically activated to produce vapor.

In the modification of FIG. 5, the operation of the vaporizer 12 in conjunction with the storage tank 11 is as described in connection with the control system 10 of FIG. 1. The operation of the remainder of the system 45 is similar to that of the system 10 except that, since the pressure responsive control valve 46 is in the pipe 25 on the outlet side of the surplus flow valve 16, the valve 46 closes rather than opens when the pres sure within the storage tank 11 reaches this set value for the valve 46, such as 20 p.s.i.g. When the valve 46 closes, no vapor can flow from the vaporizer 12. Hence, vapor can flow from the storage tank 11 through the pipe 22, the pipe 38, the back pressure check valve 47, and the gas pressure regulator 26, to the demand area. When the pressure within the storage tank 11 drops to a value below 20 p.s.i.g., the pressure responsive control valve 46 senses the drop in pressure and opens, opening the pipe 25 leading from the surplus flow valve 16. Now, vapor can flow from the vaporizer 12 through the pipe 25 and the valve 46 to the demand area. When vapor can flow through the valve 46, all the vapor demanded by the demand area will be supplied from the surplus flow valve 16 because the back pressure check valve 47 creates a pressure drop of about 3 psi. and impedes tlow through the pipe 38. This vapor will be supplied either from the vaporizer 12, the vaporizer 12 with auxiliary vapor from the storage tank 11, or

from the storage tank 11 alone, depending upon the demand for vapor and the consequent setting of the surplus flow valve 16.

Various changes and modifications may be made within the scope of this invention as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention is defined by the claims appended hereto.

lclaim:

l. A system for supplying vapor to a demand'area comprising a storage tank for containing liquid petroleum, a vaporizer,

means to deliver liquid from the storage tank to the vaporizer, means to boil liquid in the vaporizer to produce vapor, means to supply vapor from the vaporizer to the demand area, means bypassing the vaporizer for supplying vapor from the storage tank to the demand area, pressure responsive valve means in the bypass vapor supply means, the pressure responsive valve means being normally closed and being adapted to open in response to increases in pressure within the storage tank to or above a predetermined valve for alternately blocking and unblocking the flow of vapor through the bypass supply means, and a back pressure check valve on the outlet side of the vaporizer for creating a pressure drop between the inlet and the outlet of the back pressure check valve to assure deactivation of the vaporizer when the pressure responsive control valve means is open, and means responsive to a condition within the vaporizer to cut off the flow of heat to and to deactivate the vaporizer.

2. The vaporizer system of claim 1 including a surplus flow valve, a first inlet passage to the surplus flow valve, means connecting the first inlet passage to the vaporizer for delivering vapor from the vaporizer to the first inlet passage, a second inlet passage to the surplus flow valve, means connecting the upper end of the storage tank to the second inlet passage for delivering vapor from the storage tank to the second inlet passage, an outlet passage from the surplus flow valve, means connecting the outlet passage for delivering vapor to the demand area, a normally closed valve for blocking the second inlet passage and a normally open valve movable to block the first inlet passage, and means to unblock the second inlet passage when the demand for vapor increases above the capacity of the vaporizer to supply vapor.

3. The vaporizer system of claim 2 including means to close the first passage when the demand for vapor reaches such a high level that the vaporizer becomes exhausted of vapor.

4, A system for supplying vapor to a demand area comprising a storage tank for containing liquid petroleum, a vaporizer, a pipe for delivering liquid petroleum from the storage tank to the vaporizer and, under the influence of liquid pressure in the storage tank and vapor pressure in the vaporizer, for maintaining liquid in the vaporizer in proper quantity to supply the rate of vaporization in the vaporizer under normal operating conditions, a surplus flow valve. having an outlet communicating with the demand area and having a first inlet communicating with the vapor area within the vaporizer and a second inlet communicating with the vapor area within the storage tank, normally closed valve means for normally blocking the second inlet and normally open valve means for normally opening the first inlet under the said normal operating conditions, the normally closed valve means being operable in response to increases in demand for vapor above the capacity of the vaporizer to supply vapor, the normally open valve means being closeable in response to substantial filling of the vaporizer with liquid, a pipe bypassing the vaporizer and connected directly between the vapor area of the storage tank and the demand area, a normally closed pressure responsive valve in the bypassing pipe openable in response to increase in pressure within the storage tank to or above a predetermined value, and a back pressure check valve for creating a pressure drop between the vaporizer and the demand area thereby providing a greater impedance to the flow of vapor from the vaporizer than through the bypassing pipe and means responsive to a condition within the vaporizer to cut off the flow of heat to and to deactivate the vaporizer.

5. The system of claim 4 wherein the bypassing check valve produces a pressure drop of about 3 p.s.i.

6. The system of claim 4 wherein the pressure responsive valve is set to open upon sensing a pressure of about 20 p.s.i. within the storage tank.

Claims

2. The vaporizer system of claim 1 including a surplus flow valve, a first inlet passage to the surplus flow valve, means connecting the first inlet passage to the vaporizer for delivering vapor from the vaporizer to the first inlet passage, a second inlet passage to the surplus flow valve, means connecting the upper end of the storage tank to the second inlet passage for delivering vapor from the storage tank to the second inlet passage, an outlet passage from the surplus flow valve, means connecting the outlet passage for delivering vapor to the demand area, a normally closed valve for blocking the second inlet passage and a normally open valve movable to block the first inlet passage, and means to unblock the second inlet passage when the demand for vapor increases above the capacity of the vaporizer to supply vapor.
3. The vaporizeR system of claim 2 including means to close the first passage when the demand for vapor reaches such a high level that the vaporizer becomes exhausted of vapor.
4. A system for supplying vapor to a demand area comprising a storage tank for containing liquid petroleum, a vaporizer, a pipe for delivering liquid petroleum from the storage tank to the vaporizer and, under the influence of liquid pressure in the storage tank and vapor pressure in the vaporizer, for maintaining liquid in the vaporizer in proper quantity to supply the rate of vaporization in the vaporizer under normal operating conditions, a surplus flow valve having an outlet communicating with the demand area and having a first inlet communicating with the vapor area within the vaporizer and a second inlet communicating with the vapor area within the storage tank, normally closed valve means for normally blocking the second inlet and normally open valve means for normally opening the first inlet under the said normal operating conditions, the normally closed valve means being operable in response to increases in demand for vapor above the capacity of the vaporizer to supply vapor, the normally open valve means being closeable in response to substantial filling of the vaporizer with liquid, a pipe bypassing the vaporizer and connected directly between the vapor area of the storage tank and the demand area, a normally closed pressure responsive valve in the bypassing pipe openable in response to increase in pressure within the storage tank to or above a predetermined value, and a back pressure check valve for creating a pressure drop between the vaporizer and the demand area thereby providing a greater impedance to the flow of vapor from the vaporizer than through the bypassing pipe and means responsive to a condition within the vaporizer to cut off the flow of heat to and to deactivate the vaporizer.
5. The system of claim 4 wherein the bypassing check valve produces a pressure drop of about 3 p.s.i.
6. The system of claim 4 wherein the pressure responsive valve is set to open upon sensing a pressure of about 20 p.s.i. within the storage tank.