Abstract: A method for producing bleached wood pulp in which wood chips are digested in polysulfide liquor to produce brown stock pulp. The brown stock pulp is washed to produce washed brown stock wood pulp and weak black liquor and the washed wood pulp is then delignified in an oxygen delignification stage to produce oxygen delignified wood pulp. The delignified wood pulp is then ozone bleached in an ozone bleaching stage in which a waste stream principally containing ozone, carbon dioxide and oxygen is produced. The ozone-bleached pulp is introduced into an extractive oxidation stage which can include peroxide to further bleach the pulp and the product of the extractive oxidation stage is then either introduced into either a peroxide or chlorine dioxide bleaching stage.

Abstract: White liquor produced from black liquor is partially or completed oxidized. The white liquor contains dregs that are utilized as a carbon based catalyst. Dregs are produced by separating the dregs from green liquor an intermediate product between the black liquor and the oxidized white liquor. After formation of the oxidized white liquor, the dregs are separated therefrom to form a waste dreg stream which can be recycled so that part of the dregs present within the dregs containing white liquor stream to be oxidized is contributed by the waste dreg stream.

Abstract: A method of tempering an article is disclosed in which an article is heated so that the material making up the article is in an essentially stress-free state and the article thereafter is quenched and cooled. At the conclusion of the quenching, a stress pattern in initiated through the thickness of the article in which the midplane layer is in tension and the surface layers are in compression. This stress pattern is further developed during the cooling stage. The article is quenched by spraying the surfaces with a coolant, preferably comprising either liquid nitrogen or liquid air in the form of a two phase flow of liquid and vapor. The liquid is sprayed so that the surface tensile stress of the surface layers are not exceeded and the liquid does not accumulate on the surface layers as a film.

Abstract: An oxygen delignification method and apparatus in which a charge of heated wood pulp is reacted with oxygen in the presence of a charge of caustic soda in a plurality of reaction stages located between mixing stages in which caustic is mixed with the wood pulp. The use of the plurality of mixing stages reduces peak pH exposure of the wood pulp that would otherwise occur if the charges of caustic and wood pulp were mixed all at once. Moreover, the caustic mixed in such manner replenishes neutralized caustic and ensures that the average pH level is increased above that in conventional oxygen delignification. The increase in average pH level favors an increase in the delignification. Filtrate from a washing stage is introduced into the mixing stages to prevent wood pulp degradation.

Abstract: An oxygen delignification method and apparatus in which a charge of heated wood pulp is reacted with oxygen in the presence of a charge of caustic soda in a plurality of reaction stages located between mixing stages in which caustic is mixed with the wood pulp. The use of the plurality of mixing stages reduces peak pH exposure of the wood pulp that would otherwise occur if the charges of caustic and wood pulp were mixed all at once. Moreover, the caustic mixed in such manner replenishes neutralized caustic and ensures that the average pH level is increased above that in conventional oxygen delignification. The increase in average pH level favors an increase in the delignification. Filtrate from a washing stage is introduced into the mixing stages to prevent wood pulp degradation.

Abstract: A refrigeration device in which a heat load is refrigerated within a refrigeration chamber. Refrigerant is supplied, preferably, from a supply of turboexpanded air employing a compressor to compress the air and a turboexpander to expand the compressed air to a low temperature. A venturi-like device such as an ejector circulates the refrigerant within a circulation path within the refrigeration chamber so that heat is transferred from the heat load to the refrigerant. An incoming mass flow rate of the refrigerant is delivered to a high pressure inlet of the venturi-like device and a recirculation mass flow rate of the refrigerant is received within the low pressure inlet from the circulation path after the refrigerant has heat transferred thereto. A high pressure outlet discharges a mixture of the refrigerant that comprises the incoming and recirculation mass flow rates to the circulation path and prior to the heat load.

Abstract: A method of producing oxidized white liquor from white liquor in which sodium sulfide is oxidized to sodium sulfate. In accordance with the method, an oxygen containing gas is contacted with the white liquor at a temperature of at least 110.degree. C. and such that the total pressure of oxygen and water vapor is no less than 9.2 atmospheres during the contacting.

Abstract: A freezer having a freezing compartment and a porous conveyor belt for conveying articles through the freezing compartment. A vaporizer is provided to vaporize a stream of liquid cryogen. Vaporized cryogen is directed against the belt as a plurality of jets to blow accumulated ice off the belt. The vaporizer is located within the freezing compartment so that the cooling potential of the cryogen is not wasted and the vaporizer can serve as a preferential condensation site for the moisture.

Abstract: The present invention provides an improved method for firing thick film inks in hybrid circuits which comprises firing different copper compatible thick film materials in a single firing atmosphere. The method comprises the steps of providing a paste suitable for application to a ceramic substrate, applying the paste to the substrate by a conventional technique such as screen printing, drying the substrate, and firing the substrate at an elevated temperature in an ambient comprising an inert gas and carbon dioxide to form the electrical component. In another embodiment, the substrate is fired in an ambient comprising only carbon dioxide.

Abstract: A method of forming a copper circuit pattern on a ceramic substrate. In accordance with the method, first and second layers of copper oxide and copper are applied to the ceramic substrate. Selected regions of the copper are then masked so that unmasked regions are formed on the copper in a configuration of the copper circuit pattern. Masked regions are formed on the copper adjacent the unmasked regions, where copper cannot be plated. The unmasked regions of the copper are plated in a neutral pH solution by a reverse pulse plating process. The masking is then removed and the copper and copper oxide layers are etched so that the copper and copper oxide is removed from the unmasked regions. Thereafter, the remaining copper is direct bonded to the substrate.

Abstract: A method for heat processing of multilayered ceramic articles containing internal conductive metal patterns that have been formed from multiple ceramic green sheets individually coated with inks or pastes containing conductor metal/metal oxide material, and thereafter assembled in registry with each other and laminated. The heat treating method to convert the laminate to the final ceramic article includes a first heating stage under conditions to promote burn-out of the organic polymeric binder present, a second stage performed under conditions to reduce the metallic conductor, and a third stage to sinter the multilayered composite to form the final ceramic article. The invention is characterized by the presence of moisture in an amount of from about 0.5% to about 3% of the gaseous atmosphere in at least the sintering stage, and preferably at both the binder burnout stage and the sintering stage.

Abstract: The present invention provides a food processing system and method for refrigerating articles of food. The food processing system includes at least two cooling stages formed by a cryogenic freezer and a hydrocooler. The cryogenic freezer receives the articles of food and transfers heat from the articles of food to the cryogen so that the articles of food are refrigerated. After the transfer of heat from the articles of food to the cryogen, the cryogen boils off to form cryogenic vapor. The hydrocooler receives the articles of food prior to the cryogenic freezer and transfers heat from the articles of food to supplied cooling water. Such heat transfer reduces the quantity of cryogen required to refrigerate the articles of food. Additionally, an eductor is connected to a pump and to vent line from the cryogenic freezer.

Abstract: The present invention relates to a cryogen delivery apparatus and method for delivering a flowing cryogen with a regulated cooling potential. The apparatus includes a pressure vessel for receiving a liquid form of the cryogen. A liquid-vapor interface is maintained within the pressure vessel so that a gaseous form of the cryogen having a low cooling potential is situated above the liquid-vapor interface and a liquid form of the cryogen having a high cooling potential is situated below the liquid-vapor interface. An outlet conduit is provided for delivering the gas and liquid forms of the cryogen from the pressure vessel. The conduit has a moveable end section located within the pressure vessel. When the moveable end section is oscillated above and below the level of a liquid-vapor interface, a two-phase flow of cryogen is delivered comprising the pure gaseous and liquid forms of the cryogen.

Abstract: A method of joining components to a substrate by reflow soldering with non-rosin-based flux containing solder is disclosed comprising heating the solder in the presence of the components in a low oxidizing atmosphere.

Abstract: The present invention relates to an apparatus for delivery of pure gaseous and liquid forms of cryogen. The apparatus includes a pressure vessel for receiving a liquid form of the cryogen. A liquid-vapor interface is maintained within the pressure vessel by a liquid level detector and a cut-off valve connected to the level detector to vent the gaseous form of the cryogen to the atmosphere when the liquid form falls below a predetermined level. A heated overflow tube projects into the pressure vessel and is positioned at the predetermined level of the liquid. When the liquid rises above the predetermined level, it flowws into the overflow tube and is heated to vapor to add to the gaseous form of the cryogen within the pressure vessel. An outlet conduit is provided for delivering the gas and liquid forms of the cryogen from the pressure vessel. The conduit has a moveable end section located within the pressure vessel.

Abstract: A single-step process is disclosed for hermetically sealing a glass to a metal having similar coefficients of thermal expansion without carrying out the conventional pretreatment steps of decarburization and oxidization by heating to at least the melting point of the glass in an atmosphere containing from about 0.5 to 2.5 volume percent of water vapor, 0 to about 5 volume percent of hydrogen gas and the balance an inert gas, such as nitrogen.

Abstract: In a process for delignifying wood pulp with oxygen, a pulp slurry and oxygen are introduced into an elongated reactor having a plurality of gravitational fall zones at which oxygen is dissolved in the liquid phase of the slurry. The length of the reactor is sufficient to provide the residence time required for delignification reactions. Alkali is added in controlled quantities along the reactor length in response to sensed slurry pH to maintain a predetermined slurry pH throughout the reactor. The oxygen treated slurry discharged from the reactor is separated into pulp and hot recycle liquor, the latter being utilized to effect thermal, chemical and water economies.