Patents Assigned to Minnesota Valley Engineering
  • Patent number: 5572875
    Abstract: A combined second relief valve and restricted orifice is located downstream of the relief valve stack on a vent line. The second relief valve opens at a pressure greater than that of the relief stack. When the second relief valve is closed, vapor is vented through the restricted orifice at high velocity, and when the second relief valve is open, the vapor vents from the unrestricted end of the vent line at high volume.
    Type: Grant
    Filed: April 28, 1994
    Date of Patent: November 12, 1996
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Keith W. Gustafson
  • Patent number: 5542255
    Abstract: The invention consists of at least one layer of super insulation surrounding the vessel containing the cryogenic liquid. A thin layer of high temperature insulation surrounds the super insulation. Both layers of insulation are surrounded by an outer jacket.
    Type: Grant
    Filed: May 4, 1994
    Date of Patent: August 6, 1996
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Duane Preston, Thomas K. Drube
  • Patent number: 5537824
    Abstract: The fueling station consists of a vacuum insulated storage vessel for storing a large quantity of LNG at low pressure. The LNG is delivered to one of two relatively small volume fuel conditioning tanks where the pressure and temperature of the LNG can be raised or lowered as dictated by the needs of the system. The pressure and temperature in the fuel conditioning tanks are raised by delivering high pressure natural gas vapor thereto from a high pressure bank. The temperature and pressure can be lowered by venting natural gas from the fuel conditioning tanks and/or delivering LNG thereto. The fuel conditioning tanks are connectable to a vehicle's fuel tank via a fill line to deliver natural gas and LNG to the vehicle and to vent natural gas from the vehicle to the fueling station.
    Type: Grant
    Filed: January 31, 1994
    Date of Patent: July 23, 1996
    Assignee: Minnesota Valley Engineering
    Inventors: Keith W. Gustafson, George W. Kalet
  • Patent number: 5421161
    Abstract: A relief valve is provided in the dip tube line that provides a fixed back pressure of 2-3 psi. When the economizer valve on the economizer circuit opens, the back pressure in the dip tube is the head pressure plus the 2-3 psi created by the relief valve. This pressure creates a path of least resistance through the economizer circuit such that the demand of product will draw gas from the gas head via the economizer line until the pressure falls below the valve set at the regulator. Once the pressure falls below the valve set at the regulator, the regulator closes the economizer circuit and liquid will be drawn through the dip tube. Because the relief valve prevents flow back into the tank, an orifice is provided to allow back flow of the cryogen from the withdrawal line to the tank once delivery of product is stopped.
    Type: Grant
    Filed: September 27, 1993
    Date of Patent: June 6, 1995
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Keith W. Gustafson
  • Patent number: 5421162
    Abstract: Liquid natural gas is pumped into a main tank until the main tank is completely filled with liquid. Once filled, high pressure gas is pumped into the main tank. This high pressure gas forces the liquid from the main tank into an overflow tank until the liquid level in the main tank reaches a predetermined level. High pressure gas is then pumped through the main tank to the overflow tank until the LNG in the overflow tank is saturated at a pressure slightly higher than the pressure needed at the use device. Once the desired pressure is achieved the delivery of LNG to the delivery system is stopped. LNG is initially delivered from the overflow tank to the use device as a high pressure gas. Some of the high pressure gas being delivered from the overflow tank is diverted from the use device to saturate the LNG in the main tank at the desired pressure.
    Type: Grant
    Filed: February 23, 1994
    Date of Patent: June 6, 1995
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Keith Gustafson, Duane Preston
  • Patent number: 5421160
    Abstract: The fueling station consists of a vacuum insulated storage vessel for storing a large quantity of LNG at low pressure. The LNG is delivered to one of two relatively small volume fuel conditioning tanks where the pressure and temperature of the LNG can be raised or lowered as dictated by the needs of the system, The pressure and temperature in the fuel conditioning tanks are raised by delivering high pressure natural gas vapor thereto from a high pressure bank. The temperature and pressure can be lowered by venting natural gas from the fuel conditioning tanks and/or delivering LNG thereto.
    Type: Grant
    Filed: March 23, 1993
    Date of Patent: June 6, 1995
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Keith Gustafson, George W. Kalet
  • Patent number: 5404918
    Abstract: The storage tank consists of a main tank and ullage tank connected by a relatively small passage having a flow rate capacity up to 30% of the main fill line. To fill the tank, liquid cryogen is delivered to the main tank by either a top or bottom fill. Because the fill line is significantly larger than the passage, the main tank will become liquid full while the ullage tank remains substantially empty. When the tank becomes liquid full a dramatic drop in the flow rate will result that can be detected by a relatively insensitive, and inexpensive, flow monitoring device thereby to stop the filling operation. The ullage tank will retain trapped gas and gradually allow the liquid from the main tank to enter the ullage tank through the passage until the liquid level in the tanks are equal. Once the liquid levels in the tanks equalize, a vapor space is created above the liquid to accommodate vaporizing cryogen and provide long hold times.
    Type: Grant
    Filed: September 3, 1993
    Date of Patent: April 11, 1995
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Keith Gustafson
  • Patent number: 5373702
    Abstract: Two LNG storage tanks receive LNG from a fill station. The two storage tanks are connected to an overflow tank into which the LNG flows during pressurization of the system. The overflow tank is connected to the use device, i.e. the vehicle's engine, through a heat exchanger to provide high pressure natural gas thereto. The fill station initially delivers LNG to the two storage tanks until the tanks are substantially filled with LNG whereupon the fill station automatically stops delivery of LNG and begins to deliver natural gas vapor to the storage tanks until the pressure in the system reaches a predetermined maximum that is equal to or greater than the pressure required by the use device. During the pressurization of the system some of the LNG in the two storage tanks is forced into the overflow tank by the incoming natural gas vapor.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: December 20, 1994
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: George Kalet, Keith Gustafson
  • Patent number: 5275007
    Abstract: The sensor assembly includes a sensor tube in communication with the inner tank. A flush line extending from the liquid cryogen fill line is connected to the sensor tube at a three-way valve. The three way valve also connects the sensor tube to a pressure transducer. During normal operation, the sensor tube is in communication with the pressure transducer such that the level of liquid in the dewar can be monitored. When the liquid level falls below a predetermined level, the pressure transducer activates the three-way valve to connect the sensor tube to the flush line and opens a solenoid located in the fill line. As the cryogen liquid enters the fill line, a portion of it is diverted through the flush line, is vaporized and is passed through the sensor tube. The relatively warm gas flow in the sensor tube prevents the formation of ice and eliminates the problems associated therewith.
    Type: Grant
    Filed: July 14, 1992
    Date of Patent: January 4, 1994
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Timothy A. Neeser
  • Patent number: 5234035
    Abstract: A supply tank having a plurality of dip tubes extending therein is provided. One dip tube is provided for each storage tank that is to be filled by the supply tank. The dip tubes are of different lengths, and their lengths are related to the amount of syrup each dip tube is to deliver. A source of compressed gas communicates with the tank to force the syrup in the tank up the desired dip tube and into the delivery line connected to the onsite syrup storage tank. When the level of syrup in the tank falls below the end of the dip tube through which delivery is being made, the flow of fluid therethrough stops, and the compressed gas forces all of the syrup in the delivery line into the storage tank. By controlling the length of the dip tubes the amount of syrup delivered can be controlled.
    Type: Grant
    Filed: January 6, 1992
    Date of Patent: August 10, 1993
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Timothy A. Neeser
  • Patent number: 5231838
    Abstract: A vacuum insulated storage vessel holds a quantity of LNG for delivery to a pressure building tank. The pressure building tank maintains a natural gas head over the LNG. The pressure in the pressure building tank is lowered using liquid nitrogen (LN.sub.2) to condense the natural gas head and is raised by vaporizing the LNG. A valve system connects the supply of LNG in the pressure building tank to the fuel tank of the vehicle being supplied to allow either LNG or natural gas to be delivered to the vehicle tank and allows natural gas in the tank to be vented back to the fueling station. The fueling station of the invention includes suitable controls for controlling the pressure and temperature of the LNG delivered to the vehicle, the pressure and temperature in the fueling station itself and the pressure and temperature in the vehicle fuel tank.
    Type: Grant
    Filed: February 18, 1992
    Date of Patent: August 3, 1993
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Robert E. Cieslukowski
  • Patent number: 5228295
    Abstract: The fueling station of the invention consists of a vacuum insulated storage tank for storing large quantities of LNG at low pressure. A delivery line connects the LNG in the storage tank with a fill line to engage the use device such as a vehicle's fuel tank at the fueling station. A meter is provided to deliver a metered amount of LNG to the vehicle. A pump is used to sub-cool the LNG and convey it from the storage tank to the delivery hose and an eductor is provided to gradually draw vaporized LNG from the storage tank into the delivery line. The fill line, pump, eductor and delivery hose are vacuum jacketed to prevent vaporization of the LNG. A circulation loop is provided to sub-cool the pump, eductor and meter prior to delivering LNG to the vehicle in order to ensure that vaporized natural gas is not delivered to the use device. In an alternate embodiment a heat exchanger using LN.sub.2 or other coolant can be used in place of the pump to sub-cool the LNG.
    Type: Grant
    Filed: December 5, 1991
    Date of Patent: July 20, 1993
    Assignee: Minnesota Valley Engineering
    Inventor: Keith Gustafson
  • Patent number: 5228585
    Abstract: A vehicle-mounted double-walled ellipsoidal cryogenic storage vessel includes an inner vessel enclosed by an outer shell to form an insulation chamber therebetween. Both the inner vessel and the outer shell are formed in the same manner. An elliptical pressure head of circular cross-section is cut along a diameter to form two end halves. An end wall is secured between the two end halves to form an end, which is secured to an end of a wall like cross-section. This process is repeated with another pressure head to form the other end of the storage vessel. Storage vessels may be constructed of any size desired to allow sufficient ground clearance when mounted under a vehicle.
    Type: Grant
    Filed: December 11, 1992
    Date of Patent: July 20, 1993
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: H. Michael Lutgen, Keith W. Gustafson
  • Patent number: 5215128
    Abstract: The delivery system of the invention overcomes the above-noted shortcomings and consists of at least two stainless steel, rigid syrup storage tanks. The tanks are connected to a carbonated beverage mixer and dispenser via a automatic vacuum selector valve. The valve operates to change over between tanks when the tank providing syrup becomes empty and a vacuum is created in the supply line to the selector valve. The vacuum is created in the supply line by an automatically operating valve that closes the supply line when the tank is empty. A cleaning system is also provided that can be connected to the vent of the empty tank to clean it before it is refilled with syrup. A drain line cooperates with the valve to maintain the valve in its open position and allow the cleaning fluid to drain from the tank.
    Type: Grant
    Filed: June 6, 1991
    Date of Patent: June 1, 1993
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Timothy A. Neeser
  • Patent number: 5174354
    Abstract: A carbonated beverage delivery system having at least two syrup storage tanks. Each storage tank is provided with a valve that allows air to vent from the tank during delivery, acts as a nozzle to deliver cleaning solution during clean-up operations and, most significantly, meters the amount of fluid delivered to the tank and prevents inadvertent overfill. The tanks are also provided with a syrup feed pipe and drain pipe for filling and discharging the tank, respectively. The drain pipe can be connected to a mixing valve that also receives carbon dioxide and water from separate sources. These components are mixed at the mixing valve to create the desired carbonated beverage which is then delivered to a beverage dispenser. The feed pipe can be connected to a delivery truck supply tank such that its supply of syrup can be replenished. The volume of syrup carried by the truck supply tank is less than the total volume of all the storage tanks to be filled from the supply tank.
    Type: Grant
    Filed: March 20, 1991
    Date of Patent: December 29, 1992
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Timothy A. Neeser, Martin S. Taylor
  • Patent number: 5163409
    Abstract: The present invention uses an on-board source of compressed natural gas (CNG) to pressurize the LNG in the vehicle's LNG storage tanks such that high pressure natural gas can be delivered to the use device. More than one LNG storage tank can be used without increasing the amount of CNG required if the storage tanks are connected together in series so that the upstream storage tank pressurizes the downstream storage tank.
    Type: Grant
    Filed: February 18, 1992
    Date of Patent: November 17, 1992
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Keith Gustafson, George W. Kalet
  • Patent number: D339844
    Type: Grant
    Filed: May 17, 1991
    Date of Patent: September 28, 1993
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Timothy A. Neeser
  • Patent number: D344572
    Type: Grant
    Filed: August 8, 1991
    Date of Patent: February 22, 1994
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Timothy A. Neeser
  • Patent number: D372529
    Type: Grant
    Filed: June 30, 1995
    Date of Patent: August 6, 1996
    Assignee: Minnesota Valley Engineering, Inc.
    Inventor: Scott Remes
  • Patent number: RE35874
    Abstract: The delivery system of the invention consists of a pair of LNG fuel tanks mounted on a vehicle. A solenoid valve associated with each tank allows the vehicle operator to select the tank from which LNG is to be delivered to the engine. An automatic override system is provided whereby if the pressure in the non-selected tank rises above a predetermined level, the operator's tank selection is overridden and gas from the non-selected tank is used until the pressure falls below the predetermined level. This override system eliminates the need to vent gas to the atmosphere to avoid pressure building up and thereby eliminates waste of the LNG. Each tank is also provided with a pressure building capability such that the gas will always be delivered to the engine with sufficient pressure. The system is designed such that LNG from a stationary low pressure storage tank can be delivered at high pressure to refuel the tanks.
    Type: Grant
    Filed: July 6, 1994
    Date of Patent: August 25, 1998
    Assignee: Minnesota Valley Engineering, Inc.
    Inventors: Timothy A. Neeser, Kelly W. Hedegard