What are the advantages and disadvantages of LNG dual mixed refrigerant liquefaction technology as compared to LNG propane pre-cooled MCR liquefaction technology?

Answer 1

Operation in arctic climates poses additional challenges. The main challenges from a process design standpoint are, of course, the low ambient temperatures and the wide range of temperature extremes throughout the year. Average ambient temperature over the year could be about 0°C, and the temperature can vary from -40°C to 30°C. The low ambient temperatures lead to an atypical power split between the propane compressor used for pre-cooling and the mixed refrigerant compressors used for liquefaction and sub-cooling. Typically the power split is 1/3 for pre-cooling and 2/3 for liquefaction and sub-cooling. At 0°C, this shifts to about 1/4 for pre-cooling and 3/4 for liquefaction and sub-cooling. Also, this power split can vary significantly due to the wide temperature extremes. There are several options for modifying the C3MR process in order to maximise the utilisation of power available from the compressor drivers while maintaining efficient and effective refrigerant compressor operation over the wide temperature range. One of these options consists of using a mixed refrigerant in the pre-cooling instead of propane. By varying the concentrations of the refrigerants used in the pre-cooling stage, plant operators can respond to changing climatic conditions. Increasing the proportion of propane creates a heavier mix in summer, while adding ethane yields a lighter mix for winter. The Dual Mixed Refrigerant (DMR) process has been developed to overcome the limitations imposed by the use of a single component refrigerant in the pre-cooling cycle. There are many variations of the DMR process, which use a mixed refrigerant for pre-cooling. This pre-cooling mixed refrigerant is heavier than the mixed refrigerant used for liquefaction and sub-cooling. The main advantage of these cycles is that the pre-cooling mixed refrigerant composition can be adjusted on a seasonal basis as the temperature changes. The DMR process provides the highest thermal efficiency, but also the greatest equipment count, complexity and multiple refrigerant handling. Traditional C3MR pre-cooling cannot be adjusted this way. However, around the equator in places like Brunei, Nigeria, or in Northern Australia, for example, temperatures vary less, so it makes sense to use propane first.

Answer 2

Advantages of LNG dual mixed refrigerant technology: higher energy efficiency, lower methane emissions, and reduced equipment footprint. Disadvantages: higher capital cost and complexity compared to propane pre-cooled MCR technology, potential for higher operating costs.

Advantages of LNG propane pre-cooled MCR technology: simpler process design, lower upfront capital costs, and proven track record of performance. Disadvantages: lower energy efficiency, higher methane emissions, and larger equipment footprint compared to dual mixed refrigerant technology.

Answer 3

as the lng is not readily available as like CNG as the lng is not readily available as like CNG