Temperature-compensated automatic stop fill for filling of tanks with liquids under vapor or gas pressure

• US 5,673,736 A
• Filed: 09/11/1995
• Issued: 10/07/1997
• Est. Priority Date: 03/15/1994
• Status: Expired due to Fees

• Current Assignee: Edward J. Farkas
• Original Assignee: Edward J. Farkas
• Inventors: Farkas, Edward J.
• Primary Examiner(s): JACYNA, J CASIMER
• Application Number:
  US08/526,588
• Time in Patent Office: 757 Days
• Field of Search: 141/5, 141/7, 141/59, 141/44-46, 141/94, 141/95, 141/198, 141/290, 137/202, 137/386, 137/388, 137/393, 137/397, 137/587, 137/588
• US Class Current: 141/198
• CPC Class Codes: B67D 7/362 combined with over-fill preventing means indicating or measuring liquid level G01F23/00; level control G05D9/00
• CPC Class Codes: B67D 7/565 for indicating end of flow, e.g. by optical or audible signals
• CPC Class Codes: F17C 2205/0323 Valves
• CPC Class Codes: F17C 2205/0364 flexible or articulated, e.g. a hose
• CPC Class Codes: F17C 2221/035 Propane butane, e.g. LPG, GPL
• CPC Class Codes: F17C 2223/0153 Liquefied gas, e.g. LPG, GPL
• CPC Class Codes: F17C 2223/033 Small pressure, e.g. for liquefied gas
• CPC Class Codes: F17C 2223/045 with a dip tube
• CPC Class Codes: F17C 2227/0135 Pumps
• CPC Class Codes: F17C 2227/0157 Compressors
• CPC Class Codes: F17C 2227/04 Methods for emptying or filling
• CPC Class Codes: F17C 2227/045 by vacuum
• CPC Class Codes: F17C 2250/01 Intermediate tanks
• CPC Class Codes: F17C 2250/0413 with floats
• CPC Class Codes: F17C 2250/043 Pressure
• CPC Class Codes: F17C 2250/0636 Flow or movement of content
• CPC Class Codes: F17C 2250/075 when full
• CPC Class Codes: F17C 2260/022 Avoiding overfilling
• CPC Class Codes: F17C 2270/05 for industrial use
• CPC Class Codes: F17C 5/02 for filling with liquefied gases
• CPC Class Codes: Y10T 137/3099 : Float responsive
• CPC Class Codes: Y10T 137/731 : With control fluid connection at desired liquid level
• CPC Class Codes: Y10T 137/86324 : Tank with gas vent and inlet or outlet

Abstract

The invention described in the patent is an automatic control system which provides monitoring, supervision, and control of the process of filling of a tank or container with a liquid. The invention is applicable to cases where the liquid is handled in contact with its own vapor only, or where the liquid must be maintained at all times under a specified gas pressure. The invention provides an improved method of carrying out the process of filling of tanks or containers with liquids such as ammonia, chlorine, propane, liquefied petroleum gas, or with liquids such as carbonated beverages. The main advantage provided by the apparatus and method of the present invention is that an improved means is included for automatically stopping the filling process at the correct point, so as to avoid a possibly hazardous overfilled condition. One of the methods currently in use requires a mechanical valve which senses liquid level in the tank and is supposed to close so as to stop flow to the tank when the liquid has reached the maximum allowable level. The mechanical valve may malfunction and allow overfilling of the tank, and the fact that the valve is malfunctioning may not be readily apparent. The present invention does not require a mechanical valve of the type described above. Further, there is a self-checking and self-monitoring capability so that users of the apparatus and method are warned of any malfunction.

Claims

1. An apparatus for filling a tank with a liquid, said apparatus comprising:

a tank with a tank inlet and a tank outlet;

a liquid feed pump;

an inlet line with a first end connected to said liquid feed pump and a second end connected to said tank inlet, said inlet line delivering, with a first flow capacity, a liquid from said liquid feed pump to said tank;

an outlet line connected to a first side of said tank outlet, said outline line having a second flow capacity that is negligible in relation to said first flow capacity;

a sensor positioned within said outlet line at an downstream position from said tank outlet such that it is not exposed to splash-back of said liquid while said liquid is delivered to said tank, said sensor identifying a filling pressure while said liquid is delivered to said tank, said filling pressure being substantially equivalent to the pressure in said tank while said liquid is delivered to said tank;

a non-sealing float valve connected to a second side of said tank outlet, said non-sealing float valve causing a non-sealing obstruction of said outlet line when said liquid reaches a predetermined level, and allowing said liquid to flow into said outlet line if the liquid flow through said inlet line is not stopped, said non-sealing obstruction causing within said outlet line an obstruction pressure substantially less than said filling pressure, said obstruction pressure causing said sensor to generate a full tank signal; and

a microprocessor connected to said sensor to identify said full tank signal and generate a command signal to stop said liquid feed pump such that said liquid flow is halted at said first end of said inlet line.

2. The apparatus of claim 1 wherein said outlet line has an interior diameter of approximately 3. mm.

3. The apparatus of claim 1 further comprising a liquid sensor to generate said full tank signal in response to a liquid flow in said outlet line.

4. The apparatus of claim 1 wherein said non-sealing float valve includes a vertically elongated float configured to contact the seat of said float valve when the mass of liquid in said tank has reached a pre-determined maximum value substantially independent of the temperature of said liquid.

5. The apparatus of claim 1 wherein said non-sealing float valve is configured to cause a non-sealing obstruction of said outlet line at a higher liquid level when said liquid has a relatively low density.

6. A method of filling a tank with a liquid, said method comprising the steps of:

delivering, through an inlet line with a first flow capacity, a liquid to a tank;

sensing, in an outlet line with a second flow capacity that is negligible in relation to said first flow capacity, a filling pressure while said liquid is delivered to said tank, said filling pressure being substantially equivalent to the pressure in said tank while said liquid is delivered to said tank;

causing a non-sealing obstruction of said outlet line which will allow said liquid to flow into said outlet line if the liquid flow through said inlet line is not stopped when said liquid reaches a predetermined level such that an obstruction pressure substantially less than said filling pressure is formed in said outlet line, said obstruction pressure causing a full tank signal; and

responding to said full tank signal by stopping said liquid flow at the front of said inlet line.

7. The method of claim 6 further comprising the step generating said full tank signal in response to a liquid flow in said outlet line.