US-20260126152-A1 - CONTROLLED DOSING OF LIQUID CRYOGEN

US20260126152A1US 20260126152 A1US20260126152 A1US 20260126152A1US-20260126152-A1

Abstract

A liquid cryogen dosing head has a liquid cryogen reservoir in communication with a dosing outlet, a dosing valve stem having a lower, distal end configured to selectively open and close the dosing outlet, and an electromagnetic actuator attached to an upper end of the dosing valve stem above the liquid cryogen reservoir and operable to move the dosing valve stem to open and close the dosing outlet. The electromagnetic actuator is disposed above the liquid cryogen reservoir and the dosing valve stem extends through the liquid cryogen reservoir, preferably concentrically, to open and close the dosing outlet by blocking an orifice of the dosing outlet.

Inventors

Erik Robert Showers
John Walker Ross
David Tucker

Assignees

VACUUM BARRIER CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251219

Claims (20)

1 . A liquid cryogen dosing head, comprising a liquid cryogen reservoir in communication with a dosing outlet; a dosing valve stem having a lower, distal end configured to selectively open and close the dosing outlet; and an electromagnetic actuator attached to an upper end of the dosing valve stem and operable to move the dosing valve stem to open and close the dosing outlet; wherein the electromagnetic actuator is disposed above the liquid cryogen reservoir and the dosing valve stem extends through the liquid cryogen reservoir to open and close the dosing outlet by blocking an orifice of the dosing outlet.
2 . The liquid cryogen dosing head of claim 1 , wherein the liquid cryogen reservoir through which the dosing valve stem extends is sized to contain a depth of at least 10 centimeters of liquid cryogen.
3 . The liquid cryogen dosing head of claim 1 , wherein the dosing valve stem is exposed to an interior of the liquid cryogen reservoir over a distance that is at least 10 times an average lateral extent of the dosing valve stem within the liquid cryogen reservoir.
4 . The liquid cryogen dosing head of claim 1 , wherein the liquid cryogen reservoir is cylindrical and wherein the dosing valve stem extends parallel to a vertical axis of the reservoir.
5 . The liquid cryogen dosing head of claim 1 , wherein the dosing outlet comprises a valve seat positioned to be engaged by the distal end of the dosing valve stem to close the dosing outlet, and wherein the liquid cryogen reservoir extends to a level lower than the valve seat.
6 . The liquid cryogen dosing head of claim 1 , further comprising a seal extending about the dosing valve stem and separating the liquid cryogen reservoir from a cavity between the seal and the electromagnetic actuator, the seal providing an air-tight seal during operation.
7 . The liquid cryogen dosing head of claim 6 , further comprising a controller operable to perform a sterilization cycle of the head, comprising introducing a pressurized sterilization fluid into the reservoir, while introducing a gas at a countering pressure into the cavity, thereby keeping the dosing outlet in a closed condition during sterilization.
8 . The liquid cryogen dosing head of claim 6 , wherein the seal comprises a diaphragm secured to the dosing valve stem.
9 . The liquid cryogen dosing head of claim 1 , wherein the liquid cryogen reservoir is contained within a housing connecting the dosing outlet with the electromagnetic actuator, and wherein the housing and the dosing valve stem are fashioned primarily of materials with coefficients of thermal expansion that differ by less than one percent.
10 . The liquid cryogen dosing head of claim 9 , wherein both the housing and the dosing valve stem are fashioned of stainless steel.
11 . The liquid cryogen dosing head of claim 1 , wherein the electromagnetic actuator comprises a servomotor.
12 . The liquid cryogen dosing head of claim 1 , wherein the electromagnetic actuator is controllable to alter a dosing valve stem displacement distance and duration.
13 . The liquid cryogen dosing head of claim 1 , wherein the electromagnetic actuator is controllable to alter a rest position of the dosing valve stem with respect to the dosing outlet.
14 . The liquid cryogen dosing head of claim 1 , further comprising a dosing outlet gas flow valve controllable to introduce a flow of sterile gas from a pressurized source to the dosing outlet to inhibit frost accumulation.
15 . The liquid cryogen dosing head of claim 14 , wherein the dosing outlet gas flow valve is controllable to open when the electromagnetic actuator is not operating to dispense a dose of liquid cryogen.
16 . The liquid cryogen dosing head of claim 14 , wherein the dosing outlet gas flow valve includes a fixed bypass orifice that allows a continuous flow of the sterile gas to the dosing outlet when the electromagnetic actuator is operating to dispense a dose of liquid cryogen.
17 . The liquid cryogen dosing head of claim 14 , wherein the dosing outlet gas flow valve is arranged to introduce the flow of the sterile gas to a portion of the dosing outlet open to atmospheric pressure.
18 . The liquid cryogen dosing head of claim 1 , wherein the lower, distal end of the dosing valve stem comprises a thermoplastic cap that engages a seat of the dosing outlet.
19 . A liquid cryogen dosing head, comprising a liquid cryogen reservoir in communication with a dosing outlet having a seat; a dosing valve stem having a lower, distal end configured to selectively open and close the dosing outlet by engaging the seat; and an actuator attached to an upper end of the dosing valve stem and operable to move the dosing valve stem to open and close the dosing outlet; wherein the liquid cryogen reservoir extends to below the dosing outlet seat, such that liquid cryogen contained within the reservoir surrounds the dosing outlet.
20 . The liquid cryogen dosing head of claim 19 , wherein the liquid cryogen reservoir has a horizontal floor surface below the dosing outlet.

Description

CLAIM OF PRIORITY This application claims priority under 35 USC § 120 as a continuation-in-part of pending U.S. patent application Ser. No. 18/678,412, filed May 30, 2024, which claimed priority under 35 USC § 120 to U.S. patent application Ser. No. 18/425,621, filed Jan. 29, 2024 and now U.S. Pat. No. 12,031,680, which claimed priority under 35 USC § 119(e) to U.S. Provisional Patent Application Ser. No. 63/623,393, filed on Jan. 22, 2024, the entire contents of each of which are hereby incorporated by reference. TECHNICAL FIELD This invention relates to systems and methods for delivering controlled doses of a liquid cryogen, such as liquid nitrogen. BACKGROUND In some processes, it is important to deliver a known amount of a cryogenic liquid. For example, doses of liquid nitrogen are delivered to containers that are then capped immediately in a beverage packaging line so that nitrogen vaporizing after capping pressurizes the container. In that process, the amount of liquid delivered must be carefully controlled. If too little liquid cryogen is administered, the container may collapse when it experiences significant forces. If too much liquid cryogen is delivered, excessive pressure builds up in the container causing it to deform or rupture. Even when liquid cryogen (usually nitrogen) is provided as a source of inert gas in the container and not to pressurize it, cryogen delivery must be reliable and consistent without gaps or surges of liquid. Controlling the amount or dose of liquid nitrogen delivered can be difficult, particularly if the doses must be rapidly administered as is the case for a high speed canning or bottling assembly line. The large change in density resulting from vaporization of liquid means that devices dispensing a predetermined volume of fluid, such as valves, will not provide consistent amounts of cryogen unless the vapor/liquid state of the fluid is controlled. Some liquid cryogen dosing needs to be done under aseptic conditions, and some other dosing may be done under non-aseptic conditions. SUMMARY According to one aspect of the invention, a liquid cryogen dosing head includes a liquid cryogen reservoir in communication with a dosing outlet, a dosing valve stem having a lower, distal end configured to selectively open and close the dosing outlet, and an electromagnetic actuator attached to an upper end of the dosing valve stem and operable to move the dosing valve stem to open and close the dosing outlet. The electromagnetic actuator is disposed above the liquid cryogen reservoir and the dosing valve stem extends through the liquid cryogen reservoir to open and close the dosing outlet by blocking an orifice of the dosing outlet. In some embodiments, the liquid cryogen reservoir through which the dosing valve stem extends is sized to contain a depth of at least 10 centimeters of liquid cryogen. The dosing valve stem is preferably exposed to an interior of the liquid cryogen reservoir over a distance that is at least 10 times an average lateral extent of the dosing valve stem within the liquid cryogen reservoir. In embodiments in which the dosing valve stem forms a cylindrical rod above its lower, distal end, the dosing valve stem is preferably exposed to an interior of the liquid cryogen reservoir over a distance that is at least 10 times a diameter of the cylindrical rod. In some embodiments, the liquid cryogen reservoir is cylindrical and the dosing valve stem extends parallel to a vertical axis of the reservoir. In some cases it extends along the vertical axis. In some applications, the dosing outlet has a valve seat positioned to be engaged by the distal end of the dosing valve stem to close the dosing outlet, and the liquid cryogen reservoir extends to a level lower than the valve seat. Some embodiments also include a seal extending about the dosing valve stem and separating the liquid cryogen reservoir from a cavity between the seal and the electromagnetic actuator, the seal providing an air-tight seal during operation. In some applications, a controller is operable to perform a sterilization cycle of the head, including introducing a pressurized sterilization fluid into the reservoir while introducing a gas at a countering pressure into the cavity, thereby keeping the dosing outlet in a closed condition during sterilization. In some examples, the seal features a diaphragm secured to the dosing valve stem. In some embodiments, the liquid cryogen reservoir is contained within a housing connecting the dosing outlet with the electromagnetic actuator, and the housing and the dosing valve stem are fashioned primarily of materials with coefficients of thermal expansion that differ by less than one percent. Both the housing and the dosing valve stem may be fashioned of stainless steel, for example. In some applications, the electromagnetic actuator comprises a servomotor. The electromagnetic actuator may be controllable to alter a dosing valve stem displacement distance and duratio