Processing turbo-expander

Turbine type impellers, 16 699 Turbo expanders, in cryogenic processes, 13 698... 

Thus these two installations are principally different. 3S allows reaching Iowa- temperatures because early starts isentropic process and has significant pressure drop within the device. But this pressure drop can be recovered in the diffusa-. Moreova- it is insensitive to the presence of liquids (which in turbo expander can damage the turbine) and seems not to experience the hydrates formation. 

Development of the turbo-expander process allowed the design and construction of plants for recovery of liquid ethane, as well as the heavier hydrocarbon components. The turboexpander extracts useful work from the gas during expansion from a high pressure to a lower pressure. Because of the work extraction... 

A significant improvement to the process outlined above was the use of an expansion engine. Typically, in ASUs turbo expanders are used. An ideal turbo expander is isentropic and reversible. Illustrated in Figure 3.9, air at -150°F (172 K) and 90 psia (620 kPa) is expanded to 20 psia (138 kPa). In an isentropic expansion A-B, the expansion follows the isentrope with a net change in enthalpy. In reality the expansion will not be reversible and will follow a curve similar to A-C. The actual enthalpy change divided by the isentropic enthalpy change is a measure of the expander efficiency. 

An absence of phase and dynamic balance in the system makes it necessity to take into account process dynamics. This is the case for mixture motion in regions with rapidly varying external conditions, as, for instance, in throttles, heat exchangers, turbo-expanders, separators, settlers, absorbers, and other devices. Violation of thermodynamic and dynamic balance may cause intense nudeation of one of the phases (liquid or gaseous) with formation of drops and bubbles, and their further growth due to inter-phase mass exchange (condensation, evaporation) this process is accompanied by mutual interaction of drops, bubbles, and other formations, which results in their coagulation, coalescence, and breakup. 

Adiabatic expansions doing external work, resulting in a decrease in temperature. This process is carried out in a turbo-expander. 

Equations (16.20)-(16.22) can be solved in the case of an infinitely dilute mixture when either the first component or the second one is present in the gas mixture in only a small amount. Of the utmost interest is the case of a low content of the first, i.e. condensing, component. For processes occurring in a throttle, heat exchanger, or turbo-expander, water vapor or heavy hydrocarbon vapors are condensed. In natural gas, these components are, as a rule, only present in small amounts and therefore the approximation of an infinitely dilute mixture is justified. 

In the scheme of low-temperature separation, a device of preliminary condensation (DPC) is placed before the separator. This may be a throttle, a heat-exchanger, or a turbo-expander, which serves to decrease the temperature of the mixture. Upon passage of a gas-condensate mixture through these devices, the phase balance established by the flow of the mixture in the pipeline is disrupted. As a result, there will be probable formation of a liquid phase due to the process of nucleation, and transition of components from one phase to another owing to the processes of mass-exchange, evaporation, and condensation. Violation of the... 

In this process a portion of the feed gas is sub cooled and flashed down to lower operating pressure where it is supplied to the column as its top feed. The remainder of the feed gas is also expanded to lower pressure (typically using a turbo expander) and fed to the column at one or more intermediate feed points. The cold liquids supplied to the top of the column act as reflux and absorb the C2+ components for recovery in the lower bottom product. When C02 is present in the feed gas, the higher concentration of C2+ components in the cold liqnids help reduce the amoimt of C02 concentration in the upper colder section of the column. This allows a higher ethane recovery without C02 fieezing. 

The expander discharge stream enters the bottom of the upper (rectification) section of the deethanizer column. The upper section contains packed bed and lower section contains trays. The SCORE process include two side draw loop on the deethanizer that result in to significant improved NGL recovery compared to conventional processes. Heat supplied to deethanizer column through reboiler and reboiler is design to operate using LP and MP steams depending on the mode of SCORE process either TT or Turbo expander. 

A compander is a turbo expander which uses the expander work to directly drive a process compressor. The expander extracts energy from the expanding refrigerant gas, reducing the gas temperature. It uses this energy to compress warm refrigerant gas upstream of the economizer. Over the past decades, over one thousand cryogenic turbo expanders and companders have been installed and run for Air Separation Unit (ASU) service, and there is extensive experience in hydrocarbon applications. 

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