US3776283A

US3776283A - Vapor recovery system

Info

Publication number: US3776283A
Application number: US00263233A
Authority: US
Inventors: W Kramer; E Mitchell
Original assignee: Gulf Research and Development Co
Current assignee: Chevron USA Inc
Priority date: 1972-06-15
Filing date: 1972-06-15
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

A canister containing an adsorbent material is detachably mounted on a tank truck for delivery of volatile liquids. An inlet to the canister is connected through a vapor recovery hose to the vapor space in a liquid storage tank and an outlet to the canister is connected to the vapor space in a tank on the truck. As the volatile liquid is delivered into the storage tank, air displaced from the storage tank is forced via the vapor recovery hose through the adsorbent and into the delivery tank. Vapors of the liquid are adsorbed in the canister. Pressure relief means are connected to require all air entering or leaving the tank on the truck to pass through the canister.

Description

United States Patent 1 Kramer et al.

[451 Dec. 4, 1973- 1 VAPOR RECOVERY SYSTEM [75] Inventors: W. Edward Kramer, Pittsburgh;

Edward Mitchell, Valencia, both of Pa.

[73] Assignee: Gulf Research & Development Company, Pittsburgh, Pa.

[22] Filed: June 15, 1972 [21] Appl. No.: 263,233

[52] US. Cl 141/45, 55/387, 62/54, 220/85 VR, 220/86 R [51] Int. Cl 1365b 31/06, B01d 53/14 [58] Field of Search 141/52, 53, 44, 45, 141/59, 290; 55/74, 387; 220/85 VR, 85 VS, 86 R; 62/54 [56] References Cited UNITED STATES PATENTS 2,194,501 3/1940 Hooper et al... 141/59 2,802,492 8/1957 Gosselin 141/346 X 2,859,594 11/1958 Peck 141/59 X 2,976,950 3/1961 Smith.. 141/11 X 3,543,484 12/1970 Davis 55/387 3,581,782 6/1971 Onufer.... l4l/52 X 3,672,180 6/1972 Davis 62/54 Primary Examiner-l-larvey C. Homsby Assistant Examiner-Philip R. Coe Attorney-Meyer Neishloss et a1.

[57] ABSTRACT A canister containing an adsorbent material is detachably mounted on a tank truck for delivery of volatile liquids. An inlet to the canister is connected through a vapor recovery hose to the vapor space in a liquid storage tank and an outlet to the canister is connected to the vapor space in a tank on the truck. As the volatile liquid is delivered into the storage tank, air displaced from the storage tank is forced via the vapor recovery hose through the adsorbent and into the delivery tank. Vapors of the liquid are adsorbed in the canister. Pressure relief means are connected to require all air entering or leaving the tank on the truck to pass through the canister.

6 Claims, 3 Drawing Figures PATENTEU DEC 4 I975 SHEET 10? 2 Fig.

FATENTED DEC 4 i975 SHEET 2 BF 2 VAPOR RECOVERY SYSTEM This inventionrelates to a vapor recovery system and more particularly to apparatus for recovery of volatile liquids displaced from tanks loaded from a tank truck.

When gasoline storage tanks at service stations are filled, a substantial volume of air loaded with gasoline vapors is displaced from the storage tank at a high rate. The gasoline vapors displaced from the tank are an important source of unoxidized hydrocarbons discharged in the atmosphere that under certain conditions cause smog. Moreover, the relatively large volume of gasoline laden air displaced from storage tanks as the tanks are filled constitutes a loss of gasoline and may create a serious fire hazard.

As the tanks on gasoline tank trucks are emptied, air

is drawn into the tanks to replace the gasoline discharge from the tanks. The air may contain a substantial volume of water vapor which may condense in the tanks and contaminate the gasoline. Condensation of water in the tanks will also cause increase corrosion of the tanks. While loss of vapors of gasoline and induction of water vapor into the tanks on gasoline tank trucks are most extensive during delivery of the gasoline, they also occur during breathing of the tank caused by changes in temperature.

During recent years a number of types of apparatus have been proposed to prevent the discharge of gasoline vapors into the atmosphere. Systems that deliver displaced vapors into absorption systems, as in U. S. Pat. No. 2,849,150 of Tompkins, or into refrigeratorcondensers, as in U.S.- Pat. No. 3,266,262 of Moragne, for liquefying gasoline vapors entrained in air displaced from tanks during loading are suitable for terminals but are too expensive and bulky for use at individual service stations. y

US. Pat. No. 3,016,928 of Brandt discloses apparatus including propellers mounted in delivery hoses to conduct vapors entrained in air from a tank being filled to a tank being emptied. No treatment of the air delivery into the delivery tank is accomplished. US. Pat. No. 2,802,492 of Gosselin and US. Pat. No. 3,581,782 of Onuffer disclose apparatus for adsorbing vapors displaced fror'n a tank being filled, but, like US. Pat. No. 3,0l6,928, do nott'reat air entering a tank truck either during delivery of liquid from the tank or when the tank breathes. US. Pat. No. 2,976,950 of Smith describes apparatus for removing water vapor from air drawn into a tank but does "not disclose apparatus for recovering vapors discharged from the tank being filled. It is an object of this invention to provide inexpensive portable equipment mounted on tank trucks that will avoid the discharge of vapors from the atmosphere during filling of storage tanks and strip vapors of water and volatile liquids drawn into tanks on tank trucks.

This invention relates to apparatus including an adsorbentscontaining canister detachably mounted on a tank truck for the recovery of volatile liquids. entrained in air displaced from tanks as the tanks are filledand for the ti'eat'mentof air drawn into the tank of a delivery truck. The canister is connectedthrough a conduitto vaporspace within tankson the truck and through a vapor line to the vapor space in atank being filled. Within the canister are means for directing vapors through the adsorbent and pressure relief valve means to control flow through the canister.

In the drawings,

FIG. 1 is a diagrammatic perspective view of a tank truck with the apparatus of this invention connected for the delivery of gasoline at a service station.

FIG. 2 is a diagrammatic view, partially in vertical longitudinal section, of the canister.

FIG. 3 is a vertical sectional view of a vent valve for connection to the vapor recovery line to the canister.

Referring to FIG. 1 of the drawings, a gasoline tank truck 10 is shown connected for delivery of gasoline into an underground storage tank 12 having a filling pipe 14. Tank truck 10 has a delivery tank 16 which may be divided into a plurality of compartments to permit a single truck to deliver several grades of gasoline. The delivery tank shown in FIG. 1 has three compartments. Each of the compartments has a separate liquid delivery line extending to a control panel 18. The liquid delivery lines 20, 22, and 24 are provided with suitable valves for control of flow through the lines. Tank truck 10 is provided with a pump, not shown, for pumping liquid from the compartments of the delivery tank into the storage tank.

Attached to the outlet of valve 20 and extending to filling pipe 14 is a delivery hose 26. Connection of the outlet end of the delivery hose to the filling'pipe 14 is accomplished by a hood 28 having an outlet 30 for vapors displaced from the storage tank 12. The detailed structure of hood 28 is not a part of this invention. Any of a number of different types of hoods having a construction which allows flow of liquid from the delivery hose 26 through the filling pipe 14 into the storage tank and simultaneous flow of vapors from the storage tank to a vapor recovery hose 32 can be used. Typical hoods, or domes as they are sometimes called, which can be used are described in US. Pat. No. 2,763,419 of G. C. Brown et al. and US. Pat. No. 2,832,378 of D. K. Beavon.

Vapor recovery hose 32 is connected at its end remote from the vapor hood 28 to a vapor recovery line 34 which serves as an inlet for'ani adsorbent-filled canister 36 illustrated in FIG. 1 supported on the outer surface of the tank 16 by brackets 38. Canister 36 is provided with inlet and outlet pipes, each of which is equipped with a suitable disconnect means, such as unions 40, topermit easy disconnection of the canister from the vapor recovery line and from avent line 44. Straps 42 releasably connected to the end of brackets 38 hold the canister securely in place on the truck. The end of thecanister 36 remote from vapor return line 32 hereinafter referred to as the outlet of the canister, is connected through vent line 44 into the vapor space in each of the compartments of tank 16.

Referring to FIG. 20f the drawings in which the canister 36 is shown partially in section, vapor return line 34 is connected to perforated vapor distributor 46 which extends longitudinally through the canister 36. A perforated vapor collecting line 48, spaced from the distributor line 36, extends longitudinally through the canister 36. Between distributor line 46 and collector 48 is an adsorbent 50 capable of adsorbing hydrocarbon vapors and water vapor from air passing through the canister. The vapor distributor 46 and collector 48 are connected near the outlet end of the canister by relief line 52 provided with a pressure release valve 54. Pressure releasevalve 54 is spring loaded to a normally closed position and is adapted to open when the pres- The adsorbent 50 should be one that will adsorb both hydrocarbon and water vapors that pass from distributor 46 to collector 48. The adsorbent may be in the form of discrete particles or a permeable bonded monolithic mass but must have sufficient permeability to allow flow of air through the adsorbent at a low pressure drop, preferably of l p.s.i. or less, when gasoline is delivered into the storage tank 12 at normal delivery rates. Activated charcoal and silica are preferred adsorbents. Adsorbent 50 may be composed of two or more adsorbents; one to strip moisture and the other hydrocarbons from air passing through the canister. The two adsorbents may be in the form of a mixture of particles of each of the two adsorbents, or the lower part of the adsorbent mass may be one type of adsorbent and the upper part a different type.

Connected to the inlet end of vapor recovery line 34 is a pressure control valve assembly 56. As is best shown in FIG. 3, pressure control valve assembly 56 comprises an inbreathing valve 58 spring loaded to a closed position and adapted to open at a pressure, for example, of l p.s.i. below atmospheric pressure. A pressure relief valve 60 is spring loaded to a normally closed position and is adapted to open when the pressure within the vapor recovery line 34 exceeds atmospheric pressure by, for example, 3 p.s.i. An emergency valve 62 in the valve assembly 56 has dimensions and a configuration to allow flow at high rates through the valve. Emergency valve 62 is spring loaded to a normally closed position and is adapted to open when the pressure within vapor recovery line 34 exceeds the atmospheric pressure by, for example, p.s.i.

In operation of the apparatus of this invention, delivery hose 26 is connected through vapor hood 28 to the filling line 14 of gasoline storage tank 12 at a service station and vapor recovery hose 32 is connected to the vapor outlet 30 of hood 28 and to the vapor return line 34. As liquid is delivered into storage tank 12, gasolineladen vapors are displaced from the tank through the filling line 14 and directed by hood 28 into the vapor return hose 32. Those vapors enter the canister 46 and flow through adsorbent 50 to the collector 48. Air stripped of moisture and hydrocarbons flows through the outlet from the canister into vent 44 and into the vapor space of tank 16. Since the volume of liquid delivered from delivery tank 16 into storage tank 12 is substantially equal to the volume of vapor displaced from the storage tank 12, the air discharged from the canister flows to the compartment of the delivery tank from which the liquid is delivered without causing any substantial change in pressure within the delivery tank. Gasoline vapors entrained in the air displaced from storage tank 12 are adsorbed by adsorbent 50 and air substantially devoid of gasoline vapors is delivered into the delivery tank 16. Similarly, moisture in the air is adsorbed by adsorbent 50. After the delivery has been completed, the vapor return hose 32 is disconnected from vapor return line 34 at valve assembly 56 and the opening to the vapor return line is closed by suitable means illustrated in FIG. 2 by a cap 64.

If, because of lowering of temperature, a partial vacuum should be created within the tank 16 while no delivery is being made from the tank, valve 58 will open to permit air to flow into the tank and relieve the vacuum. Air entering through valve 58 passes through adsorbent 50 and thereby is dired before entering the tank 16. If a rise in temperature should occur within the tank 16 with a resultant rise in pressure in the tank above the setting of valve 60, that valve will open to vent the tank and relieve the pressure. Air will flow into collector line 48 and through the adsorbent 50 to the distributor 46 and then through vapor recovery line 34 to the valve 60. Hydrocarbons in the air leaving the tank 16 are stripped from that air by adsorbent 50 before the air is vented to the atmosphere. If for any reason the pressure in vent line 34 should increase at a rate faster than it can be relieved by valve 60, such as, for example, may occur during filling of the delivery tank 16 or if the adsorbent 50 should become partially plugged, emergency valve 62 will open and air in vent line 34 is discharged at a rate high enough to relieve the pressure.

When the tank truck 10 returns to the terminal for filling of tank 16, canister 36 can be disconnected and replaced by a freshly conditioned canister in which the adsorbent 50 has been stripped of adsorbedhydrocarbons and moisture by passing high temperature steam through the adsorbent. Alternatively, a steam line can be connected to the canister 36 at one of the unions 40 and a pipe to vapor recovery equipment connected to the other union 40. Steam passing through the adsorbent 50 strips and the adsorbent of adsorbed vapors while the canister remains in place on the truck.

This invention is of greatest utility and is described for use at service stations to prevent discharging volatile hydrocarbons in the atmosphere as storage tanks at the service station are filled from tank trucks. The large number and relatively small scale of operations at service stations would make the provision of separate vapor recovery equipment at each service station extremely expensive. Although the principal contemplated use of this invention is for the recovery of volatile hydrocarbon vapors during delivery of gasoline into storage tanks at service stations, the invention can be used to recover vapors of any volatile liquids.

We claim:

1. Apparatus for the recovery of vapors of a volatile liquid entrained in air displaced from a tank through a fill pipe of the tank during filling from a tank truck comprising a delivery hose from the tank truck to the fill pipe of the tank, a vapor dome connected to the discharge end of the delivery hose adapted to receive air displaced from the tank through the fill pipe during filling, a canister mounted on the tank truck, an adsorbent for moisture and vapors of the volatile liquid in the canister, said canister having an inlet and an outlet, means within the canister for directing fluids flowing between the inlet and the outlet through the adsorbent, a vapor recovery line extending from the vapor dome to the inlet of the canister, a vent line from the outlet of the canister to a tank on the tank truck, and pressure relief means in the inlet to the canister to relieve excessively high and low pressures at the inlet.

2. Apparatus as set forth in claim 1 in which the pressure relief means include a pressure relief valve adapted to open when the pressure at the inlet exceeds a predetermined maximum operating pressure and a vacuum relief valve adapted to open when the pressure at the inlet drops below a predetermined minimum.

3. Apparatus as set forth in claim 2 including an emergency relief valve connected at the inlet, said emergency relief valve having a large opening relative to the opening in the pressure relief valve and adapted i 1 s to open at a predetermined pressure higher than said 6. Apparatus as set forth m claim 1 m WhlCh a perfopredetermined mai imum operating pressure. rated distributor connected to the inlet extends into the 4. Apparatus as set forth in claim 3 in which the adcanister, a perforated collector connected to the outlet sorbent is charcoal. extends into the canister separated from the distribu- 5. Apparatus as set forth in claim 3 in which the ad- 5 tor, a bypass pipe joins the collector and the distribusorbent is composed of two distinct materials, one of tor, and a spring-loaded valve in the bypass pipe is said materials having a high adsorption capacity for hyadapted to open at a predetermined pressure drop from drocarbons and the other of said materials having a the distributor pipe to the collector pipe. high adsorption capacity for hydrocarbon vapors.

Claims

3. Apparatus as set forth in claim 2 including an emergency relief valve connected at the inlet, said emergency relief valve having a large opening relative to the opening in the pressure relief valve and adapted to open at a predetermined pressure higher than said predetermined maximum operating pressure.

4. Apparatus as set forth in claim 3 in which the adsorbent is charcoal.

5. Apparatus as set forth in claim 3 in which the adsorbent is composed of two distinct materials, one of said materials having a high adsorption capacity for hydrocarbons and the other of said materials having a high adsorption capacity for hydrocarbon vapors.

6. Apparatus as set forth in claim 1 in which a perforateD distributor connected to the inlet extends into the canister, a perforated collector connected to the outlet extends into the canister separated from the distributor, a bypass pipe joins the collector and the distributor, and a spring-loaded valve in the bypass pipe is adapted to open at a predetermined pressure drop from the distributor pipe to the collector pipe.