TECHNJCAL FIELD OF THE INVENTION

[OOOϊ] The present invention relates generally to the field of volatile liquid vapor recovery and, more particularly, to an apparatus of relatively simple and compact design and a related method both furnishing high efficiency operation and reduced operating costs.

BACKGROUND OF THE INVENTION

[0002] When handling volatile liquids such as hydrocarbons including gasoline and kerosene, air-volatile liquid vapor mixtures are readily produced. The venting of such air- vapor mixtures directly into the atmosphere results in significant pollution in the environment and a fire explosion hazard. Accordingly, existing environmental regulations require the control of such emissions.

[QO(Bj As a consequence, a number of processes and apparatus have been developed and utilized to recover volatile liquids from air-volatile liquid vapor mixtures. Generally, the recovered volatile liquids are condensed and rccombined with the volatile liquid from which they were vaporized thereby making the recovery process more economical. f0004] Toward this end various adsorption/absorption vapor recovery systems have been developed. Examples of such systems are disclosed in, for example, U.S. Patents 5,515,686 to

Jordan, 5,591,254 to Gibson, 5,871,568 to Gibson and 5,853,455 to Gibson, all owned by the

Assignee of the present invention.

[0005] Such systems generally include (a) a pair of reaction vessels with each vessel including a bed of adsorbent for adsorbing volatile liquid vapor and producing relatively volatile liquid vapor free air, (b) a vacuum pump for regenerating the adsorbent bed in each of the reaction vessels and releasing previously absorbed volatile liquid vapor and (c) an absorber tower to enhance vapor recovery. Such devices are relatively large and require complicated piping making them generally unsuitable for small volatile liquid vapor dispensing facilities such as gasoline stations, convenience stores and even small gasoline truck loading terminals. Further, they are also not generally suitable for ground remediation equipment due to a lack of portability. The present invention addresses (his problem by providing a simplified and more compact vapor recovery apparatus that does not include an absorber tower but still operates with high efficiency.

SUMMARY OF THE INVENTION

[0006] In accordance with the purposes of the present invention as described herein, an improved apparatus is provided for recovering volatile liquid vapor from an air-volatile liquid vapor mixture. Such an air-volatile liquid vapor mixture may be collected, for example, from a volatile liquid vapor dispensing facility including a volatile liquid storage tank, a dispenser area and a vapor collector for collecting volatile liquid vapor produced at the dispenser area. [0007] The apparatus comprises: (a) a primary vapor recovery unit; (b) a first feed line connecting the vapor collector to the vapor recovery unit; and (c) a second feed line connecting the storage tank to the vapor recovery unit. The vapor recovery unit is characterized by a diffusion nozzle that discharges concentrated volatile liquid vapor recovered by the vapor recovery unit into volatile liquid held in the storage tank.

[0008] More particularly describing the invention, the vapor recovery unit includes a first vessel holding a first bed of adsorbent and a second vessel holding a second bed of adsorbent. A pump is connected to the diffusion nozzle. A valve and conduit system is provided to selectively (a) direct the air-volatile liquid vapor mixture from the first and second feed lines to one of the first and second vessels and (b) connect the pump to the other of the first and second vessels for drawing a vacuum on the bed in that vessel so as to recover previously adsorbed volatile liquid vapor now concentrated in air. An optional cooler may be provided between the pump and the diffusion nozzle. The cooler includes a heat exchanger and a chiller.

[0009] The apparatus may further include a temperature sensor connected to the first and second vessels. The temperature sensor functions to sense the operating temperature of the first and second beds of adsorbent. A controller is connected to the temperature sensor, the pump, and the valves of the system so as to provide for proper operation of the apparatus. [0010] In accordance with yet another aspect of the present invention, the apparatus may include an optional secondary vapor recovery unit. The secondary vapor recovery unit includes a third vessel holding a third bed of adsorbent, a second pump connected to the diffusion nozzle and a second valve and conduit system for (a) connecting the third vessel to a storage tank of the volatile liquid dispensing facility and (b) connecting the second pump to the third vessel for drawing a vacuum on the third bed so as recover previously adsorbed volatile liquid vapor now concentrated in air.

[0011] In accordance with yet another aspect of the present invention, a method of recovering volatile liquid vapor from a volatile liquid dispensing facility is provided. The method comprises: (a) collecting an air-volatile liquid vapor mixture from a dispenser area and a storage tank of the volatile liquid dispensing facility; (b) recovering volatile liquid vapor from said mixture; and (c) discharging concentrated volatile liquid vapor into a volatile liquid held in said storage tank through a diffusion nozzle. The method may further include the step of cooling the recovered volatile liquid vapor before discharging. In accordance with one possible embodiment of the method, the method also includes the steps of collecting an air-volatile liquid vapor mixture from a storage tank filling area of the volatile liquid dispensing facility, recovering volatile liquid vapor from the mixture and discharging concentrated volatile liquid vapor into volatile liquid held in the storage tank through the diffusion nozzle. [0012] More specifically, the method includes providing a first or primary vapor recovery- unit for recovering volatile liquid vapor from the air-volatile liquid vapor mixture produced during volatile liquid dispensing and due to thermal expansion. Further, the method includes providing a secondary vapor recovery unit for recovering volatile liquid vapor from the air- volatile vapor mixture collected during filling of the storage tank with volatile liquid. [0013] In the following description there is shown and described several different embodiments of the invention, simply by way of illustration of some of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings incorporated herein and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain certain principles of the invention. In the drawings:

[0015] Figure 1 is a schematical block diagram generally illustrating the volatile liquid dispensing facility and apparatus of the present invention; and

JOOl 6] Figure 2 is a more detailed block diagram illustrating the vapor recover} _' ^" unit and secondary vapor recovery unit of the present invention.

[0017] Reference will now be made in detail to the present preferred embodiment of the invention, examples of which are illustrated in the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Reference is now made to Figure 1 generally illustrating the apparatus 10 of the present invention in the environment of a volatile liquid dispensing facility. As illustrated, the volatile liquid dispensing facility includes a series of three storage tanks Ti ₅ T ₂ , and T ₃ . Each of the storage tanks T], T ₂ , and Tj includes a supply line SL], SL ₂ , and SL ₃ for supplying volatile liquid from the respective storage tanks, Ti, T ₂ , and T ₃ to a dispensing area D. One example of a dispensing area is a series of gasoline pumps such as found at gasoline stations and convenience stores. Typically such areas include a series of dispensing nozzles that incorporate state of the art volatile liquid vapor collectors such as manufactured, for example, by Gilbarco Veeder-Root, The volatile liquid vapor collected by the collectors is then past through a series of return lines RLu RL ₂ , and RL ₃ .

[0019] As further illustrated in Figure 1, each storage tank Ti, T ₂ , and T ₃ includes a vent line VL _h VL ₂ , and VL ₃ . Further, each vent line VLi, VL?, and VL ₃ includes a pressure relief valve PRi, PR ₂ , and PR ₃ to relieve vapor pressure from the storage tanks T ₁ , T ₂ , and T3 when that vapor pressure exceeds a predetermined pressure of the pressure relief valve PRi, PR ₂ , and PRj. As further illustrated a vapor return line 38, a pressure switch 1 18 and a cooperating valve 40 are provided between the two feed lines 14, 16 and a diffusion nozzle 54 positioned in the storage tank Tj. The vapor return line 38, pressure switch 118 and associated valve 40 allow for vapor balancing in the storage tanks in a manner described in detail later in the document. [0020] The apparatus 10 of the present invention will now be described in detail. The apparatus 10 includes a first or primary vapor recovery unit 12. The vapor recovery unit 12 is connected to the volatile liquid vapor collectors of the distribution area D by means of a first feed line 14 which connects to each of the return lines RL], RL ₂ , and RL ₃ leading from the dispensing area. Λ second feed line 16 is connected to the storage tanks Ti, T ₂ , and T ₃ through the vent lines VL ₁ , VL2, and VL3.

[0021] As will be described in greater detail below, the apparatus 10 may further include an optional cooler, generally designated by reference numeral 18. Cooler 18 includes a chiller 20 and a heat exchanger 22. In addition, the apparatus 10 may also include an optional second or secondary vapor recover}' unit 24.

[0022] Reference is now made to Figure 2 providing a more detailed illustration of the vapor recovery unit 12. As illustrated, the vapor recovery unit 12 includes a first vessel 26 holding a first bed of adsorbent 28 and a second vessel 30 holding a second bed of adsorbent 32. The adsorbent in the beds 28 and 32 has an affinity for the volatile liquid vapor. Such adsorbents are well known in the art and include, but are not limited to, silica gel, certain forms of porous minerals such as alumina or magnesia and activated charcoal,

[0023] A valve and conduit system, generally designated by reference numeral 36 includes conduits 38, 42, 48, 50, 56, 60, 62, 68, 70, 75, 76, 77 and 78 and valves 40, 44, 46, 64, 66, 71, 72, 73 and 74. A vacuum pump 52 is connected to a diffusion nozzle 54 provided below the surface of the volatile liquid L held in tank T-? through the conduit 56. The valve and conduit system 36 selectively (a) directs the air-volatile liquid vapor mixture from the first and second feed lines 14, 16 to one of the two vessels 26, 30 and (b) connects the pump 52 to the other of the two vessels for drawing a vacuum on the adsorbent bed 28 or 32 in that vessel so as to recover previously adsorbed volatile liquid vapor now concentrated in air.

[0024] The apparatus 10 may further include a secondary vapor recovery unit, generally designated by reference numeral 24. It should be appreciated that the secondary vapor recovery unit 24 is an optional feature of the apparatus 10 that allows collection of volatile liquid vapors when the storage tanks T _} . T ₂ and Ta are being filled with volatile liquid, As illustrated, the secondary vapor recovery unit 24 includes a third vessel 82, holding a third bed of adsorbent 84 and a second vacuum pump 92. A second valve and conduit system, generally designated by reference numeral 86, includes conduits 88, 94, 98, 102. 105 and 106 and valves 90, 100, 103, 104. The conduit 88 and the valve 90 connect the third \essel 82 to the \ent lines VL ₁ , VL ₂ , and VLj of the storage tanks T ₁ , T ₂ , and T ₃ (see also Fig. 1). The conduit 98 and valve 100 connect the third vessel 82 to the second pump 92 for drawing a vacuum on the third bed 84 so as to recover previously adsorbed volatile liquid vapor now concentrated in air. [0025] As also illustrated in Figure 2, the apparatus may include an optional cooler, generally designated by reference numeral 18. Cooler 18 includes a chiller 20 specifically adapted for cooling a heat exchange liquid such as brine water or a mixture of water and ethylene glycol. A pump 112 circulates the heat exchange liquid coolant in a loop between the chiller 20 and the heat exchanger 22. As illustrated, the heat exchanger 22 is provided in the conduit 56, As the concentrated volatile liquid vapor passes through the heat exchanger 22, it is cooled b) the heat exchange liquid being circulated by the pump 112 before being delivered to the diffusion nozzle 54 in the storage tank Tv

|0026] The operation of the apparatus 10 will now be described in detail. The primary vapor recovery unit 12 recovers volatile liquid vapors produced during the dispensing of product in the dispenser area D through the return lines RLj, RL ₂ . and RL ₃ and volatile liquid vapors produced by thermal expansion or other causes from the storage tanks Ti, T ₂ , and T ₃ through the vent lines VLi, VL ₂ , and VL ₃ . The secondary vapor recovery unit 24 recovers volatile liquid vapor from the storage tanks Ti, T ₂ , T ₃ through the vent lines VLi, VL _? , and VL^ when a delivery truck fills the storage tanks with volatile liquids.

[0027] When volatile liquid product is being dispensed from a storage tank (storage tank T3 in the current illustration), a slight vacuum may be developed in that tank. Initially, volatile liquid vapor that is collected at the dispenser area D travels along the return line RLi and the vapor return line 14 past the solenoid valve 40via lines 38 and 16 to the storage tanks Ti, T ₂ , and T ₃ (see Figure 1). This provides vapor balancing of the pressure in the storage tanks Tj ₃ T ₂ , and Tj, Due to a number of factors, Including but not limited to heat of expansion, dispenser nozzle vapor collection inefficiency and the splash loading of volatile liquids, typically more air-volatile liquid vapor mixture is returned through the return line RLj than liquid product is delivered from the storage tanks Ti, T> and T ₃ through supply line SL ₃ volumetrically.

[0028] A pressure switch 118 monitors the pressure in the storage tanks T ₁ , T _2* and T*. This switch 118 controls the opening and closing of the solenoid valve 40. The pressure switch 118 functions to maintain a slight negative pressure within the storage tanks Ti ₅ T ₂ , and T ₃ . When the negative pressure in the tanks Tj, ^' ϊ ^' ₂ , and T3 exceeds a first predetermined value, the switch 1 18 opens the valve 40 allowing the air-volatile liquid vapor mixture from the dispensing operation to return to the storage tanks Tj, T ₂ , and T ₃ . If the pressure in the storage tanks Ti, T ₂ , and Tj becomes too great, the switch 118 closes the valve 40. This occurs before the pressure relief valve PRi, PR; and PR ₃ on the tanks Ti, T ₂ , and T ₃ would open releasing volatile liquid vapor into the environment.

[ΘG29] When the valve 40 is closed by the pressure switch 118. the primary vapor recovery unit 12 is switched on and the air-volatile liquid vapor generated by the dispensing operation is directed to the primary vapor recovery unit 12. The pressure switch 1 18, valve 40 and conduit 38 function in the same manner when air- volatile liquid vapor is returned through the second feed line 16 from the vent lines VLi, VL ₂ , VL ₃ connected to the storage tanks Ti, T ₂ , T ₃ . [0030] As noted above, the vapor recovery unit 12 includes two vessels 26, 30 including respective beds of adsorbent 28, 32 (see Figure 2). While one vessel 26 or 30 and its associated bed 28 or 32 is being utilized to adsorb volatile liquid vapor, the other vessel 26 or 30 and associated bed 28 or 32 is being regenerated by operation of the vacuum pump 52. For purposes of this explanation, it will be assumed that the first vessel 26 and first bed of adsorbent 28 are being utilized for adsorbing volatile liquid vapors while the second vessel 30 and second bed of adsorbent 32 are being regenerated. Thus, volatile liquid vapor from the feed line 14 is directed through the conduit 38 past the open valve 40 when required to balance the tanks Tj, T ₂ , and T ₃ or through the conduit 42 past the open valve 44 and through the conduit 48 into the first vessel 26 (valves 46 and 74 are closed). If the optional secondary vapor recovery unit 24 is present, valve 90 is closed to prevent the air-volatile liquid vapor mixture from reaching the third vessel 82.

[0031] As the air and volatile liquid vapor mixture passes through the bed 28 of the adsorbent, the volatile liquid vapor is adsorbed. The clean air then passes through the conduit 76 past the open valve 72 and then through the conduit or vent tube 70 into the environment. During the adsorbing process, solenoid valves 71 and 64 are closed. The bed 28 in the first vessel 26 is designed to take the maximum possible loading of vapors generated by the dispensing facility in a give time period, such as fifteen minutes. The bed 28 allows the cleaned air to discharge into the atmosphere while collecting and concentrating the volatile organic vapors on the bed of adsorbent 28. While the bed 28 in the first vessel 26 is collecting and concentrating volatile liquid vapors, the bed 32 in the second vessel 30 is being vacuumed regenerated.

[0032] During regeneration of the bed 32, solenoid valves 46 and 74 are closed and solenoid valve 66 is opened. One way solenoid valve 73 is open at a set time during regeneration of the bed 32, otherwise it stays closed. The bed 32 is now subjected to a deep vacuum pulled by the vacuum pump 52. The vacuum pump 52 desorbs the captured volatile liquid vapors from the bed 32 drawing them through the conduit 62 past the valve 66 and along the conduit 68. After the concentrated volatile liquid vapors pass through the pump 52 they are forced through the conduit 56 to the diffusion nozzle 54 provided submerged in the volatile liquid L in tank T ₃ . [0033] Where the apparatus 10 incorporates the optional cooler 18, the concentrated volatile liquid vapors are cooled in the heat exchanger 22 before reaching the diffusion nozzle 54. Whether or not the optional cooler 18 is provided is determined by site specifics including such factors as the size of the storage tank T ₁ , T ₂ , and T ₃ being used with the diffusion nozzle 54, the altitude or elevation of the site, the ambient heat expected for the site and the vapor pressures of the volatile liquid vapor being stored. The heat exchanger 22 functions to remove the heat of compression from the discharge of the vacuum pump 52 as well as other heat absorbed from the environment in the tank and or piping during transfer. When this is done, the volatile liquid stored in the storage tank T ₃ remains cooler. Here it should be noted that if the volatile liquid L in the storage tank T ₃ heats up It will cause increased vaporization of the liquid which in turn places an additional vapor recycling burden on the apparatus 10.

[0034] The diffusion nozzle 54 discharges the saturated vapors into the tank T ₃ as "multiple ^" ' small vapor bubbles to maximize the surface of the vapors so that they may be readily absorbed into the volatile liquid in the tank.

[0035] Based on the temperature of the stored volatile liquid in the storage tank T ₃ and the vapor pressure characteristics of the same, the step of absorption may not be 100% efficient. The remaining vapors will discharge out of the storage tank T ₃ through the vent line VL ₃ back into the second feed line 16. Here the vapors will be recycled and mixed with the vapors from the dispenser area D. Thus, the vapors will pass through the vapor recovery unit 12 again. [0036] After the regeneration time cycle has ended on the bed 32, solenoid valves 66 and 73 close. Next solenoid valve 74 opens to allow for ambient air to reenter into the second vessel 30 until it reaches atmospheric pressure. After equalization of the second bed 32 based upon time, solenoid valves 46 and 74 simultaneously open. At the same time solenoid vahes 44 and 72 close and solenoid valve 64 opens. Solenoid valve 71 will open at a set regeneration time of bed 28. When this occurs, the second bed 32 in the second vessel 30 begins to adsorb volatile liquid vapor while the first bed 28 in the first vessel 26 is being regenerated by the vacuum pump 52. More specifically, the air- volatile liquid vapor mixture moves through conduits 14 and conduit 42 past solenoid valve 46 and then along conduit 50 to the second vessel 30. As the volatile liquid vapor is adsorbed on the bed 32, clean air passes through the conduit 78 past the solenoid valve 74 and then is vented to the environment through the conduit or vent tube 70. [0037] Now, the first bed 28 in the first vessel 26 is being regenerated. Specifically, the vacuum pump 52 draws air past the one-way solenoid valve 71 along the conduits 75 and 76. That air is then drawn through the bed 28 in the reaction vessel 26, desorbing the volatile liquid vapor. The resulting concentrated volatile liquid vapor is then drawn through the conduit 60, past the solenoid valve 64 and then through the conduit 68 to the vacuum pump 52. The concentrated volatile liquid vapor is then pushed by the pump 52 through the conduit 56 to the diffusion nozzle 54 submerged in the volatile liquid L contained in the tank T3. Volatile liquid vapor bubbles from the diffusion nozzle 54 and rapidly condense in the liquid L. Once the regeneration time cycle times out, the process repeats itself as long as the vapor recovery unit 12 is running due to the loading demands of the faculty,

[0038] Periodically, a tanker truck arrives to fill the storage tanks T ₁ . T ₂ , and T ₃ with volatile liquid through the re-supply pipes RSi, RS ₂ , and RSi (see Fig. 1). The optional secondary vapor recovery unit 24 is utilised to recover volatile liquid vapors generated during the filling of the storage tanks T ₁ , T ₂ . and T ₃ . That vapor travels through the vent lines VLs, VL2 or VL ₃ of the storage tank Tj, T; or T ₃ being filled. During the filling operation the solenoid valve 40 is closed and the solenoid valve 90 is opened. Thus, the volatile liquid vapor travels from the vent line VL]. VI. ₂ or VL ₃ through the second feed line 16 and conduits 38 and 88 past the solenoid valve 90 and into the third vessel 82. During this process the solenoid valves 100 and 103 are closed while solenoid valve 104 is open. Volatile liquid vapor is adsorbed on the bed 84 and clean air passes through the conduit 102, past the solenoid valve 104 where it is vented into the environment through the conduit or vent tube 106. It should be appreciated that the bed 84 has the capacity to adsorb the maximum amount of volatile liquid vapor that may be generated during the filling of the storage tanks Ti, T;, and T ₃ .

[0039] After each tank has been saturated, the bed 84 is regenerated. In order to do this, valves 90 and 104 are closed and valve 100 is opened. Valve 103 will open based on a set vacuum time on bed 84. The vacuum pump 92 is then activated to draw a vacuum. Thus, air is drawn out of the bed 84 for a set time then the valve 103opens and allows air to travel from valve 103 through the conduits 105 and 102 into the third vessel 82. As that air passes through the bed 84 it desorbs the volatile liquid vapor. The resulting air stream with a high concentration of volatile liquid vapor is drawn from the vessel 82 along the conduit 98 past the valve 100 to the pump 92. fhe pump 92 then pushes the concentrated volatile liquid vapor stream through the conduits 94 and 56 toward the diffusion nozzle 54. The concentrated volatile liquid vapor diffuses through the nozzle 54 and the resulting bubbles provide a surface area that allows the volatile liquid vapor to quickly condense and be absorbed in the volatile liquid L in the storage tank T ₃ . It should be appreciated that if the apparatus 10 includes the optional cooler 18, the concentrated volatile liquid vapors from the bed 84 pass through the heat exchanger 22 where they are cooled prior to diffusion through the diffusion nozzle 54, [0040] Operation of the apparatus 10 may be automatically controlled by a dedicated microprocessor or controller such as MicroLogic Allen Bradley model 400 programmable logic controller. Such a controller 200 (see Figure 1) is connected to and controls operation of all valves 40, 44, 46, 64, 66, 71, 72, 73, 74, 90, 100, 103, 104 and all pumps 52 and 92(and if required the chiller 20 and pump 112) of the apparatus. The controller 200 also includes a timer for the regeneration cycles. A temperature sensor 202 may be provided to monitor the temperature of the beds 28, 32, 84 in each vessel 26, 30, 82. The temperature sensors 202 may be provided in the vent tubes 70, 106. The temperature sensors 202 are also connected to the controller 200. If the temperature of any one of the beds 28, 32, 84 rises above a certain predetermined temperature, the controller 200 will shut the apparatus 10 down. [0041] Based upon the above description of the operation of the apparatus 10, it should be appreciated that the method of the present invention may be broadly described as comprising the steps of collecting an air-volatile vapor mixture from a dispenser area and storage tank of a dispensing facility, recovering volatile liquid vapor from that mixture and discharging concentrated volatile liquid vapor into volatile liquid held in the storage tank through a diffusion nozzle. When the apparatus 10 is equipped with the optional cooler 18, the method also includes the step of cooling the recovered volatile liquid vapor before discharging. [0042] The secondary vapor recovery unit 24 allows the collecting of an air-volatile liquid vapor mixture from the storage tank during filling of that storage tank with volatile liquid. This of course is followed by the recovering of a volatile liquid vapor from that mixture and the discharging of the concentrated volatile liquid vapor into the volatile liquid held in the storage tank through the diffusion nozzle. Still further, the method includes providing a first vapor recovery unit for recovering volatile liquid vapor from the air-volatile vapor mixture collected during volatile liquid dispensing and due to thermal expansion. Further, the method includes providing a secondary vapor recovery unit for recovering volatile liquid vapor from the air- volatile liquid mixture collected from the storage tank during storage tank filling with the volatile liquid.

[0043] In summary, numerous benefits result from employing the concepts of the present invention. By delivering the concentrated volatile liquid vapor directly to the volatile liquid L in the storage tank T ₃ through the diffusion nozzle 54, it is possible to complete all vapor recovery absorption inside the storage tank and eliminate the need for an absorber tower. The capital cost of the apparatus 10 is significantly reduced by eliminating the supply pump, return pump and all equipment associated with the absorber tower. Operation costs are also significantly reduced. More specifically, since the absorber tower supply and return pumps are eliminated, the maintenance and operating costs for those pumps are also eliminated. Operation is optimized at all times. Thus, whenever possible, dispenser vapors are brought to the apparatus 10 before sending them back to the storage tanks T| , T ₂ and 1\. This minimizes (1) the amount of air returning to the storage tanks and (2) the further generation of vapors in the tanks to saturate this fresh air.

|0044] In addition, the apparatus is made more portable. Specifically, in its most basic form the apparatus 10 essentially comprises two vapor recovery vessels 26. 30 and a vacuum pump 52 which may be positioned upon a relatively small skid. The recycle line 56 can simply be a flexible hydrocarbon resistant hose to which the diffusion nozzle 54 is attached before simply being dropped into the storage tank 1\ , T ₂ , Tj.

[0045] The optional secondary vapor recovery unit 24 is particularly beneficial as it now allows, for example, the local privately owned service station to collect and keep the vapors generated during the storage tank filling process and the economic recovery associated therewith. Currently, when a tanker truck drops its load, all the vapors are returned to the terminal via the truck and the terminal gains the recovery benefit even though the service station has installed the piping to return the vapors to the truck.

[0046] Significantly, whether the apparatus 10 incorporates only the primary vapor recovery unit 12 or both the primary and secondary vapor recovery units 12. 24, the apparatus 10 may be positioned on a small skid which is capable of sitting right up on the canopy of the service station if desired.

[0047] The foregoing description of the preferred embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims in their fair and broad interpretation in any way.