JPS6056966B2 - Method and apparatus for removing steam gas from a fluid storage tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for removing gasoline vapor emissions at a service station or other location where gasoline is transferred from one tank to another.

More particularly, the present invention relates to the control and removal of gasoline vapors that may be released when gasoline is transferred from gasoline distribution tank cars to underground storage tanks and then pumped by service station pumps to motor vehicle gasoline tanks. Gasoline vapor losses at service stations are primarily from underground storage tanks, which are subject to both breathing and displacement losses. This breathing loss is caused by expansion and contraction of the tank contents due to temperature differences between day and night. Such temperature differences can be minimized by using different tanks at the gasoline storage station. When refeeding a partially empty or completely empty storage tank, expulsion losses typically occur because a volume of vapor equal to the gasoline supplied is expelled to the atmosphere through the storage tank's discharge pipe. A number of systems that have been proposed so far address this problem, including vapor equilibrium transfer systems in which the liquid and vapor spaces are interconnected between two vessels in which the liquid is transferred, oil absorption methods,
These include high-pressure compression systems, absorption of hydrocarbon vapors with activated carbon, refrigeration of saturated exhaust gases, and disposal of residual hydrocarbons in exhaust gases by combustion devices.

The present invention relates to a system for burning exhaust gas while maintaining high combustion efficiency even when the characteristics of the exhaust gas vary over a wide range.

A primary object of the present invention is to control and prevent the release of significant amounts of gasoline vapor into the atmosphere at gasoline service stations.

It is an object of the present invention to provide a method and method for controlling the release of gasoline vapor under normal and varying ambient conditions of varying pressure and temperature and under varying vapor pressure and temperature of gasoline being distributed and transferred. The purpose is to disclose the device.

Another object of the present invention is to detect steam pressure generally below atmospheric in a discharge pipe extending from an underground storage tank, and to remove excess steam in the discharge pipe upon detection of rising steam pressure within a preselected range. It is an object of the present invention to disclose a method and apparatus for the control and removal of gasoline vapor emissions that are completely combusted instead of being guided to an incinerator and discharged into the atmosphere.

One of the benefits of maintaining steam pressure slightly below atmospheric pressure
The first is to prevent the flow of gasoline vapor from a closed system. The present invention is directed to a method for removing vapor gases from a storage tank during the transfer of fluids, including liquids and gases, to or from a storage tank, wherein at least one storage tank is vented to the atmosphere. an evacuation device, the method comprising: detecting the pressure of the gas at the evacuation device; directing the gas in the evacuation device along a suitable route to the incinerator at a preselected sub-atmospheric pressure; directing combustion air into the incinerator to mix with the gas to provide substantially complete combustion and igniting and combusting this mixture in the incinerator when a preselected pressure of include.

The present invention also contemplates a device for the removal of gasoline vapor emissions from a discharge pipe in a liquid gasoline storage tank, the device comprising: a device for detecting the pressure of the vapor gas in said discharge pipe; a device for placing the burner device in communication with the exhaust pipe under a preselected pressure condition of the steam in the exhaust pipe; and a device for igniting the burner device.

A particular object of the present invention is to provide a vapor discharge control system as described above which operates in response to a vapor detection device to vacuum pump said vapor to said bar device and to substantially inject a preselected amount of air into said burner device. Another object of the present invention is to provide an injector that mixes with the steam to provide complete combustion.

According to the invention, the injector device may consist of two injectors of different capacities, and the burner device may include a burner element associated with each injector. These two burner elements have coaxially arranged burner sections for selective simultaneous or separate combustion within a common coaxially arranged chimney arrangement. Furthermore, according to the invention, a chimney device may be provided with an outer and an inner chimney pipe cooperating with one or both burner elements during combustion. Further objects and advantages of the invention will become readily apparent from the following description of the accompanying drawings, which illustrate exemplary embodiments of the invention. FIG. 1 schematically depicts the facilities of a gasoline station for the storage and distribution of liquid gasoline and the control and removal of gasoline vapors.

Normally there should be substantially no excess steam released to the atmosphere at the service station. Generally, a gasoline pump 10 is attached to a distribution hose 11 with a nozzle 12 inserted into a supply opening 14 of a gasoline tank 15 of a motor vehicle.
is provided. The gasoline pump 10 is connected by a gasoline line 17 to an underground liquid gasoline storage tank 18, the storage tank shown being filled with liquid gasoline to a level indicated at 19. liquid gasoline level 1
The space above 9 contains air and gasoline vapor, and the volume of the space changes as liquid gasoline is removed from or supplied with tank 18. Similarly connecting the storage tank 18 and the pump 10 is a gas vapor line 22 which communicates with the gasoline vapor above the liquid level in the tank 18 which had an opening 23 at the top of the tank 18. are doing. A steam line 22 runs along the distribution hose 11 and enters the supply opening 14 at the distribution nozzle 12 to communicate with the gasoline tank 15 of the motor vehicle. A means of preventing excess gasoline vapor from being released into the atmosphere from a motor vehicle gasoline tank is to use an effective sealing device (Fig. (not shown). The vapor line 22 provides a sealed closed path at the supply port 14 and communicates the vapor of the gas in each space above the liquid level of the motor vehicle gasoline tank 15 and the underground storage tank 18, respectively. In this way, storage tank 18
a closed vapor-tight liquid gasoline circulation system from to the motor vehicle gasoline tank 15 and an exhaust system for communicating and passing vapor between the spaces above the gasoline level in the motor vehicle gasoline tank 15 and above the liquid level 19 in the storage tank 18; is provided. Figure 1 also shows underground storage tank 1.
A similar closed vapor-tight gasoline liquid and vapor circulation system between 8 and the gasoline distribution tank car 25 with tank 26 is also described. The gasoline level in tank 26 is generally indicated at 27. Distribution tank car 26 is connected to underground storage tank 18 by supply hose 28 . The hose 28 is suitably provided with a manifold connection 30 and the chamber 32 is defined by a partition or barrier. The ends of the supply hoses 28 are connected to appropriate valves 29 in the manifold section and tank supply pipes 31, which supply pipes 31 have their bottom ends 32 located near the bottom of the storage tank 18 and are supplied from the bottom. I try to do that.
A sealed valve connection is provided to prevent fluid loss or gasoline vapor loss from the end of hose 28. The flow of liquid gasoline from tank 26 to storage tank 18 normally falls by gravity when the valve is opened.
Distribution tank 26 is also connected to a gasoline vapor line 33 and to a supply port 34 located at the top of tank 18.

The gasoline vapor line 33 is provided with a check valve or block valve 34a as appropriate. Line 33 is also connected to a steam line 33'' of the tank car, optionally via a valve 34b. Steam line 33 is provided with a number of connections 35, each communicating with one of the chambers of distribution tank 26. Therefore, a closed, vapor-tight liquid and gas communication system is provided between the distribution tank 26 and the underground storage tank 18 for transferring liquid gasoline from the distribution tank 26 to the storage tank 18 and providing a path for gasoline vapors. Preferably, steam lines 22 and 33 are connected to tank 18.
It enters the storage tank 18 near the end. The transfer of gasoline liquid and vapor in the two cases mentioned above, i.e. from the storage tank to the motor vehicle gasoline tank and from the distributed gasoline to the storage tank, is carried out under a closed vapor-tight sealed system and the gasoline vapor Prevent losses to the atmosphere.

However, the system must be able to operate safely under many different conditions of liquid gasoline and gasoline vapor temperature, pressure, volume, etc. that affect the escape of gasoline vapor from a closed system. For this purpose, the storage tank 18 is provided with a tank steam outlet 40, the outlet 41 of which is preferably connected to the steam line 2.
At the end of the tank opposite the area 2, 33, tank 1
It is located at the top of 8. A discharge port 42 is provided at the top of the exhaust pipe 40 to vent the gasoline vapor to the atmosphere under certain extreme conditions. A pressure car vacuum and blowout safety valve 44 may be provided at the outlet 42, which safety valve 44 is -11.7(:TA(-4.6'')WC).
and +14. (+S7l) WC pressure and +30.
It operates with a blowing pressure of 5 (+12") WC. Figure 1 shows 1
Although only one underground storage tank is shown, each gasoline service station may have three or more storage tanks for different types of gasoline.

The supply and outlet ports for each tank may be arranged in the same manner as described for tank 18. The discharge pipes of each tank are combined into a discharge header pipe 46. The present invention contemplates a means for controlling and eliminating the release of vapors from gasoline service stations such as those previously described; The release of steam is achieved by directing such exhaust gases under certain pressure conditions to an incinerator to substantially completely burn the hydrocarbons in the exhaust gases.
Can be controlled and eliminated.

The controlled removal device in this example is configured to operate in a two-stage exhaust gas pressure relief mode, as typically found in service stations. This means that the release pressure from distribution tank car tanks to underground storage tanks is relatively low (0" to 0.5" WC).
), and when the release pressure is relatively high (−
1.3c! n (-0.5'') WC). Two such relief pressure stages involve the handling of liquid gasoline at different pressures, temperatures and volumes. The gasoline vapor discharged at each stage is A predetermined amount of air is required to ensure complete combustion and minimize undesirable hydrocarbon-type air pollutants.In this example, the two-stage control-removal means of the present invention A combustion or steam incinerator is provided with a pressure car vacuum and blow relief valve 44 and a storage tank 18, generally indicated at 45.
It is equipped with a means to send exhaust gas from the

A discharge header line 46 is connected to the discharge pipe 40 between the tank 18 and the valve 44 at a point 47 . Pressure switches 73, 95, 51 and 81 (see Figure 2)
Depending on the pressure selected to drive the exhaust gases, the exhaust gases are routed through an exhaust header line 46 to a gasoline vapor-air mixer (see FIG. 1), generally indicated at 48. The piping and electrical connections are shown in detail in FIGS. 2 and 3, respectively. The steam-air mixer 48 and the incinerator 45 are configured to mix a suitable steam-air mixture so that the incinerator 45 incinerates at least 90%, generally about 99.9%, of the hydrocarbons supplied from the exhaust gas steam. It is designed and constructed to be able to feed a mixture to this incinerator 45 . In the example shown in Figures 1 to 3, the control removal means is operatively connected to each of several underground storage tanks and also controls the number of pumps used at one time and the number of pumps used at one time. Depending on the number of tanks supplied,
It can be operated to control and remove the vapors released thereby. For the sake of simplicity and clarity, the configuration of the control and removal means according to the invention will be described in detail only with one tank. The car vacuum safety valve 44 is normally closed to prevent gasoline vapors from the underground storage tank 18 from escaping through the exhaust pipe 42.

This valve 44 can be regulated to a pressure of +14.5C71 (+5.7'') WC, when the vapor pressure in the underground storage tank becomes too large while supplying liquid gasoline to the underground storage tank. Similarly, when liquid gasoline is removed from underground storage tank 18, pressure vacuum valve 44 opens to relieve such pressure.
The vacuum side of valve 44, adjusted to rfi (-4.6") WC, opens to allow air at atmospheric pressure into the exhaust pipe to prevent cavitation or destruction of the walls of storage tank 18. In this way, the pressure and vacuum It will be appreciated that the safety valve 44 provides safe control of the supply of liquid gasoline to and removal from underground storage tanks, and normally prevents the escape of gasoline vapors into the atmosphere. One of the two stages involved in such controlled removal means is when gasoline is supplied from an underground storage tank to a motor vehicle gasoline tank, and the aforementioned discharge line is connected to the motor vehicle gas tank as well as to the underground storage tank. It is assumed that the product is sealed to prevent leakage.

In the first stage, ie, supplying liquid gasoline to a motor vehicle gasoline tank, the gasoline liquid level in the underground storage tank 18 is slightly lower when the liquid is pumped to the motor vehicle gas tank. In a motor vehicle gasoline tank, as gasoline liquid is supplied into the tank, the gasoline vapor within the tank is purged and directed through the exhaust line 22 into the vapor space within the underground storage tank 18. If the temperature and hydrocarbon saturation of the liquid gasoline in the storage tank and the gasoline vapor in the motor vehicle gasoline tank are equal, there is no need to vent the vapor to the atmosphere. However, if the vapor from a motor vehicle gasoline tank becomes colder or less saturated than the gasoline and vapor in the storage tank, the cold vapor expands and requires pressure relief, otherwise the underground storage tank Pressure builds up. On the other hand, if the vapor from the automobile gasoline tank were to have a higher temperature than the gasoline in the storage tank, the vapor delivered to the storage tank would immediately contract, creating a negative pressure in the storage tank unless air was added. It turns out. When supplying gasoline from a tank car to an underground storage tank, the vapors of the underground storage tank are forced out through line 33 and returned to the space above the gasoline level 27 of the tank car.

If the gasoline in the tank car is cooler and has less hydrocarbon saturation than the gasoline in the storage tank, then the hot gasoline vapor from the storage tank that is delivered to the tank car will contract. Therefore, it is necessary to add air to the space above the liquid level 27 in the tank car, otherwise a pressure drop in the tank car will occur. If the outside air temperature and the temperature inside the tank car are higher than the temperature of the gasoline vapor coming from the underground storage tank, the pressure in the tank car will increase as the cooler storage tank vapor is heated by the warmer tank car walls. ●Increases as it is expanded. Therefore, the effect of gasoline vapor transfer between storage tanks and distribution tank car tanks and motor vehicle gasoline tanks is that regardless of whether the temperature of the stored gasoline is high or low, the transfer of gasoline vapor between storage tanks and distribution tank car tanks or motor vehicle gasoline tanks is As long as it is connected to the system, it has the opposite effect on the expansion-contraction relationship of steam that occurs in this closed steam system.
The conditions are the same whether gasoline is pumped into a motor vehicle gasoline tank and, at the same time, gasoline is supplied from a distribution tanker to a storage tank. The pumping rate that supplies gasoline to a motor vehicle gasoline tank at a service station will probably not exceed 113.5e per minute. The feed rate by gravity from a distribution tank car is, for example, 15140e1 per minute, or 151 per minute.
4e, which is currently considered the average supply rate for underground storage tanks. At one condition stage of the system according to the invention, namely, when the waste pressure is relatively low and the vapor volume is small, the gasoline exhaust vapor in line 46 is responsive to the vapor pressure and is capable of collecting gasoline vapor. the pressure as low as possible, depending on the pressure required for
For example, about -0.5C! It is controlled by a pressure switch 51 which can adjust the pressure from fl (-0.2"") WC to -1.3d (-0.51) WC.

The means for vacuum pumping gasoline vapor to the incinerator 45 is 2.
．． It consists of a suitably pressurized air source (not shown) capable of supplying air at a suitable pressure of about 1-7k9/CTi (gauge). Such pressurized air enters the system through a manual cock valve 66 at a position indicated by the reference numeral 65 (see Figure 2).
, enters the air pressure regulator 6 through an air line 67. A selected pressure is detected by the pressure switch 51 and the solenoid air valve 69 is driven. Solenoid air valve 69 directs air at a selected pressure through continuous line 67 to mixer 62 and injector 62a at atmospheric pressure. Mixer 62
For example, HauckMfg. It may also be a high-pressure air gas booster BIGlO7A (a combination of a mixer and an injector) manufactured by Komatsu. An air pressure gauge 70 is connected to line 67 and an air pressure switch 71 is coupled to the air pressure gauge to provide a selected pressure of, for example, 1.4k9/Cfi. When the pressure switch 51 is closed,
Gasoline vapor that has accumulated in the system and in tank 18 is released by solenoid valve 55 driven by pressure switch 71. Steam passing through solenoid valve 55 increases steam velocity in the reduced diameter section of the vibe 57 and then passes through check valve 58, flame arrester 59, and pressure tap device 6.
0 to an injector 62a and mixer 62 with a capacity of approximately 22,700 Kcal per hour in this example. The mixer 62 is connected to a flame sustaining burner nozzle 63. When the pressure switch 71 is closed, the solenoid valve 55 opens,
An appropriate flow rate of gasoline vapor is applied to complete combustion of the two gasoline vapors. Burner 63 is -1.65c!
The fire is extinguished when the steam pressure drops to the level of the adjustment pressure of the pressure switch 73 of about n(-0.65'') WC.

This pressure level is determined by the pressure drop of the selected system to prevent appreciable leakage of gasoline vapor to the outside. If gasoline is to be supplied to an underground storage tank at a high rate, a greater rate of combustion than that provided by burner 63 is required.

Under such conditions, for example -0.25c1n(-0
．． 12) Pressure switch 81 regulated to WC drives air solenoid valve 92 in air line 87. Air line 87 communicates with main air supply line 93. The air line 87 is appropriately provided with an air pressure regulator 94.
Pressure switch 81 drives a solenoid valve 92 in line 87, which directs pressurized air to pressure switch 71a.
The pressure switch 71a, in turn, drives a solenoid valve 82 to release gasoline vapor in line 54.
Line 54 has a larger diameter than line 53, providing a passage for a larger volume of gasoline vapor. Solenoid valve 82
sends gasoline vapor to line 83 in a smaller diameter vibrator than the vibrator in line 54 to increase vapor velocity. Gasoline vapor from line 83 is transferred to check valve 8
It passes through a flame arrester 85, a pressure tap-gauge 86, joins an air line 87 at the injector 88, and is sent to a mixer 89. The capacity of this injector is approximately 6.33kg/
Approximately 252,000 Kca1 per hour at C7lf air pressure
For example, a combination of a Hauck BIG23OA mixer and an injector may be used. Mixer 89 supplies an air-steam mixture to burner 90 . When the pressure of the exhaust gas decreases to the level adjusted by the pressure switch 95, for example about -0.760 (-0.3'') WC, the burner is extinguished. The pilot device that ignites the burners 90 and 63 is Natural gas or propagate gas from cylinders 100 may be utilized as appropriate, and these gases may be
The gas is sent to the pilot burner 101 via a thermo-pilot relay provided with an on-off valve 102, a pressure regulator 103, and a pilot gas valve 104.

This pilot burner 101 ignites the air-steam mixture during either or both of the two combustion stages of the system according to the invention. If pilot burner 10
1 disappears for some reason, such as a strong draft or propane supply cut off,
The system is inoperable, and at such time the pilot shuts down the entire system as described below in connection with FIG. Burners 63 and 90 send the products of combustion to the chimney tube system.

This chimney tube arrangement consists of a vertically arranged outer tube 106 (approximately 2.44 m high and 15.2 cm 71 cm in diameter), of sufficient height and diameter to ensure that sufficient air is available to burn all of the steam. It is said. This chimney device may be located within a service station and has a minimum distance of at least 70 cm from the open discharge pipe 42 of the gasoline pump or tank.
．． 67TL. Preferably, the chimney pipe is 2.5 mm above ground level.
44Tr1, installed at the height. These safety considerations prevent gasoline vapor from flowing near the building or near the incinerator pilot flame when the safety valve 44 is opened. The central axis of the burner 63 coincides with the central axis of the chimney pipe 106, passes through the burner 90, and intersects with the arcuate central axis of the burner 90.

The tip 63a of the burner 63 is located at the center of the burner 90, and is below the tip 90a of the burner 90. The upwardly facing portions of burners 63 and 90 have a common central axis. The small diameter pipe 107 located in the chimney pipe 106 and coaxially has a height of approximately 1.83 m and an outer diameter of 6.03 C7.
1 and the lower part of this tube is spaced above the tip 90a of the burner 90 to provide a smaller combustion chamber for the burner 63. By retracting and arranging the tip 63a of the burner 63 and the small-diameter inner tube 107, it is possible to effectively perform combustion with a smaller burner inside the structure required for a burner with a large capacity. . Inner tube 107 serves to contain the air-gas mixture of burner 63 and prevents premature cooling of the mixture before combustion L is complete. This chimney device introduces air through the bottom of the outer tube 106 and the opening 108,
A sufficient amount of air is provided to the air-gas mixture produced in the mixer and burner sections to cause substantially complete combustion of the hydrocarbons in the mixture.

From the schematic diagram shown in FIG. 3, the operation of the two-stage burner system briefly described above will be easily understood.

As shown in FIG. 3, the power supply is generally 115V, 160 cycles, single phase, as indicated by reference numeral 11-0, and is provided with a ground 111, a fuse 112, and an on/off switch 113. Connected between the leads of circuit 114 is a suitable lamp 115 to indicate whether power is present in the system. Thermopilot relay system 104 may be connected to terminals 104a and 104b through a junction box. An appropriate lie 'Fll6 is provided to indicate that the pilot burner is burning normally. The operation of the burner system shown in FIG. 2 may be better understood with reference to FIG. 3, which is a schematic electrical arrangement for actuating several pressure switches and solenoid valves.

It should be noted that in FIG. 3, the square boxes represent the terminals on the remote panel board, and the hexagonal boxes represent the terminals on the junction box near the combustion device. The square and hexagonal symbols represent terminals only in electrical systems; when power is applied and the pilot is turned on as described above, the lead wire 120 from terminal 121 is routed through panel terminal 122. The pressure switch 73 is connected in series with the pressure switch 51. Pressure switch 73
is -1. The pressure switch 51 may be adjusted to -1.3 cm (-0.5") WC, while the pressure switch 51 may be adjusted to -1.3 cm (-0.5") WC. Underground storage tank 18 during gasoline supply
As the expulsion pressure increases, it is clear that the pressure switch 73 is normally closed for pressures above -1.65d (-0.65") WC and for pressures above -1.65" WC. Pressure switch 51 closes when selective waste pressure is seen on the panel. The circuit is completed between the terminal 123 and the connecting terminals 124 and 125 of the solenoid valve 69, and the length is approximately 3.5 to 7 k.
9/d is supplied to the mixer 62a and the burner 63. In some devices, larger orifices may be used if there is insufficient air pressure within the system to draw such vapors. When the pressure switch 51 is closed in this way, the lamp 126 lights up to indicate that the discharge pressure has been reached.
Control relay contact 1 between panel terminals 122 and 123
A control relay 128 provided with 29 bypasses the pressure switch 51.

The contacts of control relay 128 are normally open and close when pressure switches 73 and 51 are closed. control relay 1
28 has a pressure of -1.6 cm. When the solenoid valve 6 is between 65" WC and -1.
It is used to prevent the start and stop (on-off) of the operation of 9. This control relay serves to keep the solenoid valve pulled until pressure switch 73 is open, covering the difference in pressure range between the two switches. This may also be done using a single switch with a large pressure differential. When the waste air pressure is as described above, the air supplied to the burner closes the pressure switch 71.

The lead wire 130 has one end connected to the panel terminal 123 and the other end connected to the panel terminal 131 via the pressure switch 71. When this pressure switch 71 is closed, it opens a solenoid valve 55 connected between connecting terminals 132 and 133. At the same time, the lamp 134 is turned on and the system is regulated.
3. When the thermopilot relay is in the "closed" state, the presence of the steam gas and air mixture in burner 63 causes ignition of the mixed air and steam to effect substantially complete combustion of the gas vapor.

Under certain gasoline supply conditions where the waste pressure increases rapidly, a small burner and injector are not sufficient to reduce the pressure and a larger capacity burner system is required. When the thermo-pilot relay is in the "closed" state, lead wire 140 is connected to panel terminal 121 and one side of pressure switch 95, which is connected to panel terminal 141 and pressure switch 81. -1.3C7 when reaching the chosen disposal pressure
The pressure switch 95 adjusted to R (-0.5'') WC and the pressure switch 81 adjusted to -0.250 (-0.1I) WC are both closed, and the circuit from the panel terminal 142 to the solenoid valve 92 is closed. and pressurized air to injector 8
Supply to 8. As seen in the foregoing discussion, the control relay 143 is provided with a pair of normally open control relay contacts 194 that connect to the panel terminals 141.
-1.3c7n (-0.5'') WC and -
Starting and stopping operations of the solenoid valve are prevented in a pressure range between 0.2''(-0.1'') WC.

A lead wire 147 is connected from the panel plate terminal 142 to a pressure switch 71a, and when the pressure switch 71a is closed, it is connected to connection terminals 149 and 150 via a panel terminal 148, and when the solenoid valve 82 is opened. Steam gas flows to burner 89. Under such conditions, light 152 will be on to indicate that burner 90 is operating. It should be understood here that the burner device 63 in the burner device 90 also continues to burn at the same time as the burner device 90 burns in the chimney pipe 106, and the steam pressure exceeds the value adjusted for the pressure switches 51 and 81. This means that combustion will continue as long as there is. As can be seen, when the steam pressure in the exhaust system falls below the pressure level regulated at pressure switches 73 and 95, the opening of switches 73 and/or 95 will cause the respective solenoid valves 69 and 92 to release the steam gas. solenoid valve 5
5 and 82 open, burners 63 and 90
stops. Obviously, the pressure switch and solenoid valve will not operate unless the thermopilot switch 104 is closed and the pilot burner is activated.

Opening thermopilot switch 104 shuts down the entire electrical system. Furthermore, when operating the above system, the control relay is used to prevent start/stop operation and maintain the "start" condition unless the pressure switches 73, 95 reach their regulated pressures, and the discharge This prevents gas from escaping to the atmosphere and makes the system immediately responsive to changes in gas vapor pressure in the exhaust line from changes in vapor conditions in the underground storage tank 18.

In this example, the burner devices 63 and 90 each have a power consumption of approximately
It has been said that combustion of 000 Kcal is possible.

These selected b...capacity of the burner equipment and the negative pressure adjustment value of the pressure switch depend on the geographical location of the service station, in particular the latitude, the type of gasoline stored (ethyl carrier addition, or regular, etc.) and the service station It may change somewhat depending on the surrounding temperature in the region, especially seasonal changes. Reid vapor pressure (ReidVapOrPreS) of gasoline distributed to service stations
Sl]Re) can vary, being higher in winter, lower in summer, and lower at higher latitudes. The respective adjustments of the steam incineration system at each service station will vary somewhat. 0.77kg/Clt at 15.6a
Examples of the Btu content of gasoline with a-lead vapor pressure are shown in the following table.

The But value of gasoline vapor without air is approximately S'32,000 Kca11d. As will be clear to those skilled in the art, different conditions must be considered in different service stations in order to determine the appropriate pressure adjustment value of the pressure sensing device and the capacity of the two burners; Excess vapor pressure is handled appropriately.

These different conditions include the number of gallons of gasoline sent to underground storage tanks, the number of locations to be distributed at one time,
Gasoline temperature in the distribution tanker, time (in minutes) allowed to transfer gasoline from one tank to another,
These include the maximum amount of excess steam volume expected, such as 1-10% of the volume of gasoline supplied, and the But value of the gas. For example, according to the invention, the steam-air mixture fed to the burner is approximately 40% gas vapor. Atmospheric air coming in through the chimney accounts for 60% of the Btu content of the airless gasoline vapor, which, with a properly designed combustion chamber for such equipment, can reduce the amount of gasoline exhaust vapor. provides a suitable mixture that allows for virtually complete combustion. Pressure adjustment decisions must take into account the fact that operating at lower pressures consumes more steam and is more expensive to operate.

If there is insufficient negative pressure, excessive leakage will occur at the dispensing nozzle 12 and the selected pressure differential system will not operate as intended. If the pressure differential ranges are adjusted too closely, which is undesirable, the burner will be operated too often, resulting in system fatigue and increased maintenance costs. Therefore, depending on the many conditions present in each device,
Adjust the pressure detection switch appropriately to the pressure difference range for optimal operation. As will be appreciated by those skilled in the art, the methods and apparatus of the present invention readily adapt to changing operating conditions, are effective in eliminating air pollution from such sources, and are comparable in equipment and maintenance. It is inexpensive to operate, and driving is actually automated.

The exhaust line piping ensures that the gas vapors during gasoline transfer pass through the vapor space from one end of the storage tank to the other before the vapors are discharged and combusted. As can be seen from the foregoing, the method and apparatus of the present invention are provided for the virtually complete incineration of undesirable hydrocarbons by gasoline vapors emitted at gasoline service stations.

Although previous examples of the invention have concerned vapors from gasoline, the method of the invention can also be practiced with other volatile liquids that provide exhaust gases above the explosive limit. The term 66 gasoline herein also includes such other liquids.

[Brief explanation of the drawing]

Figure 1 shows the transfer paths for liquid gasoline and gasoline vapor between the distribution tank car and the underground storage tank, and between the storage tank and the fuel tank of the vehicle, and how the gasoline vapor from the underground storage tank exits from the exhaust pipe. A schematic illustration of a gasoline service station illustrating the path of combustion of excess exhaust gas vapors under preselected conditions to an incinerator; Figure 2 illustrates the control of exhaust gas vapors from an underground storage tank; A simplified piping diagram and FIG. 3 are simplified electrical connection diagrams used in the control system shown in FIG. 2.

Claims (1)

Claims: 1. A method for removing vapor gases released from a storage tank during the transfer of a fluid, including liquids and gases, from or to a storage tank, the method comprising: is subjected to changes in pressure, temperature and volume, and at least one of said storage vessels is provided with means for venting to the atmosphere;
Providing steam communication means between two or more of the storage tanks; Detecting the pressure of the gas in the exhaust means; directing the gas in the exhaust means through an appropriate route at a preselected pressure close to atmospheric pressure; guiding them to the incinerator;
When the preselected pressure is detected, directing combustion air into the incinerator to mix it with the gas for substantially complete combustion; and igniting and combusting the resulting mixture in the incinerator. A method for removing vapor gas from a fluid storage tank, comprising the steps of: 2. Said step of guiding said gas in said evacuation means to an incinerator at a preselected pressure is within a pressure differential range including a pressure below atmospheric pressure at said evacuation means? ? The method described in Section 1. 3. A method as claimed in claim 1, including the step of communicating all gases with said reservoir provided with said evacuation means. 4. Providing gasoline vapor line means between two or more of said storage tanks to provide communication between the vapor spaces above the liquid level of said storage tanks; gas vapor from one vapor space of said storage tanks to the burner means; 2. The method of claim 1, further comprising the steps of: providing a discharge line; and directing gasoline vapor into and from a vapor space in the storage tank. 5 detecting a vapor pressure selected for one condition of liquid transfer to and from said storage tank to direct vapor from said liquid in said selected first burner means; 5. The method of claim 4, comprising the step of burning under one condition. 6 detecting a vapor pressure selected for different conditions of liquid transfer to and from the storage tank and combusting the vapor from the liquid in a separate second burner means; , the method according to claim 5. 7 first and second burner means for burning steam are combined in one chimney pipe means, one of the burner means extending into the other burner means, both of which burner means are connected to said chimney pipe means; 7. The method of claim 6 including the step of providing a coaxial outlet. 8. The method according to claim 4, wherein the step of igniting and burning the steam includes intermittently igniting and burning the steam in response to steam pressure detected in a steam exhaust line. . 9. The method of claim 9, wherein said step of directing steam in said discharge line to burner means comprises simultaneously supplying air to said burner means to effect substantially complete combustion of the steam-air mixture in said burner means. The method described in Scope No. 4. 10. An apparatus for removing gasoline vapor emissions from a discharge pipe of a liquid gasoline storage tank saturated with gasoline vapor in the storage tank, the storage tank having a discharge pipe to the atmosphere in communication with said vapor. a device for detecting the steam gas pressure in the exhaust pipe; a burner device; the burner device is arranged in the exhaust pipe to communicate with the exhaust pipe under a preselected near-atmospheric pressure condition of the steam; and a device for igniting said burner device. 11, wherein the device for placing the burner device in communication with the exhaust pipe includes a communication line with a normally closed solenoid valve device, and further includes a communication line with a normally closed solenoid valve device, and in response to a selected exhaust gas pressure, the device includes a communication line with a normally closed solenoid valve device; 11. The apparatus of claim 10, further comprising a pressure-responsive switching device in the communication line for activating a pressure-responsive switching device. 12 an injector actuated in response to the sensing device to vacuum pump the vapor to the burner device and mix a preselected amount of air with the vapor for substantially complete combustion in the burner device; 11. The apparatus of claim 10, comprising: 13 including a vapor-tight exhaust line between the storage tank and the supply tank connected to the storage tank at a location remote from the exhaust line and conveying all vapor from the storage tank to the exhaust line; , the apparatus according to claim 10. 14. The device for detecting steam pressure and vacuum in the exhaust pipe includes a preselected range of pressure differences, and the igniter of the burner device detects and ignites pressures within the range of pressure differences. Apparatus according to claim 10. 15. said injector comprises a first injector of a selected capacity and a second injector of a capacity different from that of said first injector, said burner element being in communication with each said injector; and the burner element comprises coaxially arranged burner sections for selective simultaneous or separate combustion within a common coaxially arranged chimney arrangement. Equipment described in Section. 16. The apparatus of claim 15, comprising a chimney arrangement with an outer and an inner chimney tube cooperating with one or both of the burner elements during combustion. 17 A device normally operated at sub-atmospheric pressure for removing gasoline vapor emissions from the discharge pipe of a liquid gasoline storage tank, the storage tank being saturated with gasoline vapors, a steam gas pressure switch device disposed on the discharge pipe for detecting steam gas pressure in the discharge pipe; a pressure air source; and a pressure air source in communication with the pressure air source. an injector device; a burner device in communication with said injector device; a device for guiding steam gas from said discharge pipe to said burner device at a selected steam pressure; said injector device, said burner device and said guide device are connected to said steam gas pressure switch. a device operative in response to a device to direct the vapor gas to the burner device for mixing with a selected amount of air from the pressurized air source for substantially complete combustion; and igniting the combustion device. An apparatus for removing vapor gas from a fluid storage tank, comprising; 18. The device for guiding steam gas from the discharge pipe to the burner device at a selected steam pressure comprises: a steam guide line from the discharge pipe to the injection device; a valve device provided in the steam guide line; an air line from a source to the injector, an air pressure switch device disposed in the air line, the valve device being actuated by the pressure switch device in response to operation of the steam gas pressure switch device; , the apparatus according to claim 17.