Compressors casing material

Compressors used for low-temperature applications have always required special low-temperature casing and rotating element materials. Decreasing temperatures make some metals less ductile, thus making them more susceptible to brittle failure. Minimum acceptable temperatures for a number of metals utilized for cast casing material, welded casing material, and impeller material are listed in Table S.8. 

In the case of a liquid recycle, the cost of this pressure increase is usually small. Pumps usually have low capital and operating costs relative to other plant items. On the other hand, to increase the pressure of material in the vapor phase for recycle requires a compressor. Compressors tend to have a high capital cost and large power requirements giving higher operating costs. 

Turbine-Blade Cooling The turbine inlet temperatures of gas turbines have increased considerably over the past years and will continue to do so. This trend has been made possible by advancement in materials and technology, and the use of advanced turbine bladecooling techniques. The olade metal temperature must be kept below 1400° F (760° C) to avoid hot corrosion problems. To achieve this cooling air is bled from the compressor and is directed to the stator, the rotor, and other parts of the turbine rotor and casing to provide adequate cooling. The effect of the coolant on the aerodynamic, and thermodynamics depends on the type of cooling involved, the temperature of the coolant compared to the mainstream temperature, the location and direction of coolant injection, and the amount of coolant. 

Lubricated cylinders use a separate mechanical lubricator to force feed, in metered droplet form, a very precise amount of lubricant to specified points. This minimizes the amount of lubricant in the cylinder and allows a lubricant most compatible with the gas to be selected without compromising the frame lubrication system. Lubricant is fed to a point or points on the cylinder to service the piston rings and the packing when required. In a few cases, as in air compressors, the packing is lubricated from the crankcase. On some applications involving wet CO7 or H2S m the gas stream, special materials may be avoided if one of the lubrication points IS connected to the suction pulsation dampener. 

For compressors in general and for some types in particular, the cleanliness of the gas stream is the key factor in a reliable operation. Moisture or liquids in various forms may be the cause of an early failure or in some-cases a catastrophic failure. Corrosive gases require material considerations and yet even this may not entirely solve the loss of material issue that can certainly cause early shutdowns or failures and high maintenance cost. Fouling due to contaminants or reactions taking place internal to the ( i-pressor can cause capacity loss and the need for frequent shutdowns. 

Selection of construction materials for rotors and casings is more limited than for centrifugal compressors. 

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