COREFLUX®: High Efficient NGL/LPG Recovery Process

Summary

TOYO Engineering Corporation (TOYO) has developed COREFLUX (Cold Reflux), the new processes to extract Natural Gas Liquid (NGL) from natural gas and/or LNG utilizing a unique reflux enhancement method. The COREFLUX processes can achieve a high product recovery rate with a relatively low energy consumption.

COREFLUX®-C2

COREFLUX®-C2 (Cold Reflux Technology for C2 recovery) is a very efficient and competitive process technology to obtain a high ethane recovery rate from natural gas, oil associated gas and off-gas from refinery plants. This process can recover more than 95% of ethane from feed gas at less compression power compared to the conventional split vapor process within the same range of initial investment cost of conventional technologies.

The features of this process are;

  • High ethane recovery rate ( >95%) with enhanced reflux,
  • Low compression power with an efficient use of a turbo expander
  • Easy modification from the conventional process

COREFLUX®-C2 utilizes turbo expander to cool down the feed gas. However, unlike the conventional split vapor process, all of the feed gas is sent to the turbo expander to maximize the power recovery. To produce a methane rich reflux, a gas-liquid separator is provided at the outlet of the turbo expander. The methane rich vapor from the separator is recompressed by a compressor and totally condensed against the cold stream from Demethanizer overhead. The condensed liquid contains high concentration of methane and works as an effective reflux. Maximum power recovery at the turbo expander and the methane rich reflux have resulted in a lower total compression power for COREFLUX®-C2 compared with the conventional processes.

In 2014, COREFLUX®-C2 has been selected by State Concern “Turkmengas” for a 5 billion m3 natural gas per annum NGL recovery facility located in Turkmenbashi, Turkmenistan.

COREFLUX®-C2 will achieve a high process performance for the following applications.

  • For high ethane recovery,
  • For relatively rich feed gas and
  • For revamp project to increase feed throughput and/or ethane recovery rate.
COREFLUX-C2 Process Flow

COREFLUX®-C2 Process Flow

COREFLUX®-LNG

COREFLUX®-LNG Process (Cold Reflux Technology for LNG Processing) is an efficient LNG processing technology to recover ethane and LPG from LNG. This technology can reduce the heating value of LNG at the LNG regasification terminal and utilize the recovered ethane and LPG as petrochemical feedstock.

Photo: Courtesy of Oil & Natural Gas Corporation Limited (ONGC)

In 2006, COREFLUX®-LNG Process was selected for a large scale of C2-C4 extraction facility in Dahej, India (5 million tons per year of LNG processing capacity) by Oil and Natural Gas Corporation (ONGC).

The features of this process are;

  • High ethane recovery rate ( >98%) with enhanced reflux,
  • Low energy consumption with an advanced cold heat integration, and
  • Simple flow scheme for easy operation and maintenance with reasonable initial investment cost.

COREFLUX®-LNG involves a condenser in Demethanizer overhead, where the Demethanizer overhead vapor is partially condensed against the cold LNG feed stream. A part of condensed liquid from the condenser is returned to Demethanizer as reflux. This reflux contains more than 99 mol% of methane. This is the reason why COREFLUX®-LNG can achieve more than 98% of ethane recovery rate. The remaining vapor from the condenser is compressed with an overhead compressor before being fully condensed against the feed LNG. For energy conservation, a methanol heating medium, suitable for cold heat transfer, is applied.

COREFLUX®-LNG will provide an additional value to LNG regasification terminal

i.e. an opportunity to sell petrochemical feedstock in addition to regasified natural gas, and thus, will improve the economics of LNG regasification terminal. For example, COREFLUX®-LNG can be applied to the following regasification terminals.

  • Where high heating value LNG is received under a long-term contract,
  • Where lower heating value LNG is accepted by users and
  • Where a petrochemical plant is available to receive ethane and LPG.
COREFLUX-LNG Process Flow

COREFLUX®-LNG Process Flow

COREFLUX®-LPG

COREFLUX®-LPG Process (Cold Reflux Technology for LPG Extraction) is unique LNG processing technology to extract LPG from LNG. This technology can reduce the heating value of LNG at LNG regasification terminal and utilize the extracted LPG as petrochemical feedstock in the similar way with COREFLUX®-LNG.

The features of this process are;

  • High C3/C4 recovery rate (> 99.5%) with enhanced reflux
  • No vapor compression for reliquefaction of Demethanizer overhead
  • Low energy consumption with low operation pressure of Demethanizer

COREFLUX®-LPG is the two columns process, where a high propane recovery rate can be achieved with an ethane rich reflux recycled back from Deethanizer to Demethanizer. Overhead vapors from both Demethanizer and Deethanizer columns are fully condensed by feed LNG and cold heat recovery from Demethanizer. This unique reflux enhancement method enables total condensation of vapors without any overhead vapor compression at low operation pressure, which can maximize the separation efficiency of C2 and C3.

COREFLUX®-LPG will provide an additional value to LNG regasification terminal

  • Where high heating value LNG is received
  • Where lower heating value LNG is accepted by users (e.g., power plants etc.)

This process can be applied when LPG is sold as a product or supplied to Propane Dehydrogenation (PDH) unit as the feedstock. COREFLUX®-LPG can easily be upgraded as COREFLUX®-LNG to extract not only LPG but also ethane by providing one cryogenic LNG compressor depending upon the downstream petrochemical demand.

COREFLUX-LPG Process Flow

COREFLUX®-LPG Process Flow

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