Abstract: The refrigeration system for an ethylene plant comprises a closed loop tertiary refrigerant system containing methane, ethylene and propylene. The tertiary refrigerant from a compressor final discharge is separated into a methane-rich vapor fraction and two levels of propylene-rich liquids so as to provide various temperatures and levels of refrigeration in various heat exchange stages while maintaining a nearly constant refrigerant composition flowing back to the compressor and with the bulk of the total return refrigerant flow going to the first stage compressor section. This tertiary system can also be applied to an ethylene plant with a high pressure demethanizer.

Abstract: Presented is an improvement to a previous invention involving the catalytic hydrogenation of the C2 to C5 and heavier acetylenes and dienes in a thermally cracked feed stream without significantly hydrogenating the C2 and C3 olefins. The improvement involves the use of a fixed bed hydrogenation reactor system in combination with a modified version of the catalytic distillation unit used in the prior art. The modification to the catalytic distillation unit involves improvement of the liquid recycle scheme. The fixed bed reactors combined with the modified catalytic distillation allows for 100% conversion of acetylene and helps to maintain high conversion of the other dienes and acetylenes with no ethylene or propylene conversion under a variety of conditions. These condition variations include but are not limited to the feed diene and acetylene composition, the mol % carbon monoxide in the feed, and catalyst deactivation.

Abstract: The refrigeration system for an ethylene plant comprises a closed loop tertiary refrigerant system containing methane, ethylene and propylene. The tertiary refrigerant from a compressor final discharge is separated into a methane-rich vapor fraction and two levels of propylene-rich liquids so as to provide various temperatures and levels of refrigeration in various heat exchange stages while maintaining a nearly constant refrigerant composition flowing back to the compressor and with the bulk of the total return refrigerant flow going to the first stage compressor section. This tertiary system can also be applied to an ethylene plant with a high pressure demethanizer.

Abstract: In a speech recognition system, a method for using multiple cursors for dictation and correction of text can include a series of steps. The steps can include detecting whether a correction marker has been included within a body of text and searching for a user specified portion of text to be corrected within the body of text. The method further can include selecting the user specified portion of text and substituting an alternate user specified portion of text for the user specified portion of text within the body of text. The step of locating the correction marker within the body of text at a location defined by the alternate user specified portion of text further can be included. Additionally, the method can include the step of relocating an insertion cursor to the end of the body of text.

Abstract: A refrigeration system for an ethylene plant uses a low pressure demethanizer and a binary refrigerant comprising a mixture of methane and ethylene or methane and ethane. The refrigeration composition may be constant throughout the system or separators may be used to divide the refrigerant into a methane-rich binary refrigerant and an ethylene- or ethane-rich binary refrigerant.

Abstract: In an olefins plant for the production and recovery of ethylene and propylene, the hydrogenation of the C.sub.2 acetylenes, the C.sub.3 acetylenes and dienes and the C.sub.4 and heavier acetylenes, dienes and olefins and the selective separation of the resulting products is carried out by the use of various arrangements of one or more reaction distillation columns. These columns contain a hydrogenation catalyst in enriching and stripping sections and concurrently perform a catalytic hydrogenation reaction and a distillation function.

Abstract: Cyclohexane is catalytically oxidized to produce cyclohexanol and cyclohexanone and precursors of these products. The product is then catalytically hydrogenated while the product is still at reaction temperature to produce additional cyclohexanol and cyclohexanone from the precursors. The oxidation is carried out in a liquid oxidation reactor at high oxygen concentrations (greater than 30% and preferably greater than 90% oxygen concentration) and at relatively low temperatures (less than 160.degree. C.). The use of the liquid oxidation reactor permits the use of these high oxygen concentrations without forming dangerously high levels of oxygen in the overhead gas phase. The result is an increased yield and selectivity of the desired products. The hydrogenation is carried out in a reactor using a catalyst of palladium supported on carbon.

Abstract: The C.sub.2 to C.sub.5 and heavier acetylenes and dienes in a thermally cracked feed stream are hydrogenated without significantly hydrogenating the C.sub.2 and C.sub.3 olefins. Additionally, the C.sub.4 and heavier olefins may be hydrogenated. Specifically, the cracked gas feed in an olefin plant is hydrogenated in a distillation reaction column containing a hydrogenation catalyst without the necessity of separating the hydrogen out of the feed and without any significant hydrogenation of the ethylene and propylene. A combined reaction-fractionation step known as catalytic distillation hydrogenation is used to simultaneously carry out the reactions and separations while maintaining the hydrogenation conditions such that the ethylene and propylene remain substantially un-hydrogenated and essentially all of the other C.sub.2 and heavier unsaturated hydrocarbons are hydrogenated. Any unreacted hydrogen can be separated by a membrane and then reacted with separated C.sub.

Abstract: A pneumatic valve actuator having a rotatable output shaft is provided with a valve positioner comprising an axially displaceable spool valve and a pneumatic transducer responsive to applied signal air pressure for displacing the spool valve away from a neutral position to effect rotation of the actuator output shaft. The actuator output shaft is gear-connected to an element which rotates with the output shaft, and an elongated cantilever beam spring attached at one end to the rotatable element extends in a direction transverse to the axis of rotation of said element to the transducer for providing a feedback force which balances the control signal responsive transducer force when the actuator output shaft has rotated to a desired position.