Abstract: The invention relates to systems and methods for delivering controlled doses of a liquid cryogen. Controlling a restriction in a return conduit and other system geometry maintains proper circulation through a delivery and return conduit, enabling reliable control over the temperature and pressure of the liquid cryogen at the site of dosing.

Abstract: A system for delivering a controlled stream of purified liquid cryogen from an outlet. The system includes a cryogen delivery flow path that is made up of a delivery conduit connecting a source of liquid cryogen to the outlet. A cryogen purifier positioned in a section of the conduit, is capable of purifying (sterilizing) liquid cryogen flowing therethrough, and a section of the delivery conduit downstream of the cryogen purifier is clean (sterile). The system also includes a cleansing flow path for cleansing (sterilizing) the cryogen purifier and the clean delivery conduit section. The cleansing flow path includes a cleansing conduit connecting a source of cleansing (sterilizing) medium to the delivery conduit and the cryogen purifier. The cryogen purifier and clean delivery conduit section are isolated from the cryogen source during conduit cleansing, and cleansing is accomplished without subjecting the cryogen source to the cleansing medium.

Abstract: An apparatus for chilling and shrinking workpieces being conveyed to a workstation on an assembly line comprises, a chilling chamber, a conveyer for transporting workpieces, at least one generally vertical conduit for transporting cryogenic liquid out of a bath to an outlet above the bath, wells for storing cryogenic fluid bath, baffles for slowing the counterflow of cryogenic vapor and a lid for maintaining vapor in the chilling chamber. The workpieces first go through the pre-cooling process where cryogenic vapor flows in a counterflow to chill the workpieces. The workpieces move through openings in the baffles, and after the pre-cooling process, the conveyer transports the workpieces to the cooling stage where baths of cryogenic liquid are stored in wells. Generally vertical conduits are immersed in the wells. The density of cryogenic fluid in the conduit is reduced by warm vapor, enabling the cryogen to flow up the conduit.

Abstract: Liquid cryogen is added to a container of particulate material (e.g. powder, flakes or granules) immediately before the container is capped as part of a process for pressurizing the container. A liquid cryogen retainer is positioned within the unsealed container above the particulate material, and the flow of liquid cryogen is directed to the retainer to substantially prevent eruption from the container of the particulate material, which may otherwise result when the liquid nitrogen penetrates the particulate material and causes the particulate material to erupt, with an unacceptable loss of the particulate material and of the liquid cryogen.

Abstract: Workpieces (e.g. valve seats, valve guides, or cylinder liners for an internal combustion engine) are chilled as they are supplied to a station on an assembly line, using a feeder/chiller that includes a passage to convey workpieces downwardly from a location at the top of the passage to an assembly line station. The chiller/feeder is fed cryogen from a reservoir of liquid cryogen. Because cryogen fluid (chilled nitrogen vapor) entering the passage is denser than air, downward flow of cryogen fluid must be restricted. For example, the passage includes a constriction below the position at which cryogen is fed to the passage. The constriction is configured and sized to allow workpieces to move through the constriction, yet the constriction is small enough to restrict the downward flow of cryogenic fluid when a workpiece is positioned in the constriction. Above the constriction, the cooling passage is large enough to allow sufficient clearance around workpieces to permit an upward flow of cryogenic fluid.

Abstract: Containers are pressurized by adding a controlled amount of liquid cryogen to uncapped containers as they move along an assembly line to a capping station. The liquid cryogen is added to the containers in a stream from a conduit outlet. The amount of cryogen delivered is controlled by sub-cooling the liquid cryogen as it flows across a flow-control restriction in the conduit, thereby ensuring that flow across the restriction is liquid. Control is also achieved by maintaining the temperature of the cryogen delivered from the outlet low enough to avoid detrimental flashing.

Abstract: A controlled stream of liquid cryogen is delivered from a system comprising: (a) a source of liquid cryogen at a substantially constant pressure, remote from the outlet; (b) a conduit connecting the liquid cryogen source to the outlet; (c) means to maintain cryogen flowing through the conduit sub-cooled at all points along the conduit (i.e., at any given point in the conduit, the cryogen's equilibrium vapor pressure is below the pressure experienced at that point in the conduit), and to deliver the cryogen to the outlet at a temperature equal to or below its boiling point at atmospheric pressure; and (d) a flow-rate control restriction, positioned in the conduit. By maintaining the cryogen sub-cooled, the flow is kept substantially (at least about 95% by volume) liquid. Therefore, the flow in the conduit is controlled reliably as to pressure, flow rate, and size.

Abstract: Apparatus for delivering cryogenic liquid to a heat exchanger wherein said liquid is vaporized for its cooling effect comprising a return conduit for conveying from a heat exchanger to a separator vessel spent fluid including some vapor, the return conduit discharging at its upper end into the portion of the vessel holding vapor, a return port for receiving spent fluid from an exchanger, a bypass passage constricted at its upper end providing a flow path in parallel with flow through an exchanger from a feed junction to a more elevated return junction, the flow being conducted in an upwards direction to the feed junction and from the feed junction into the bypass passage, the apparatus providing closed loop circulation of cryogenic liquid to a heat exchanger, with the driving force for the circulation being supplied by the differential head between cryogenic liquid in the feed conduit and spent fluid in the return conduit.