Plate Heat Exchanger for LNG


The increasing global carbon intensity has been considered as the most challenging issue these years, and maritime shipping contributes nearly 3% of annual carbon-dioxide emissions. LNG, as a transitional marine fuel, has been considered to be used in the shipping business given the economic and technologic feasibility compare to the other alternative fuels. HFM has been devoted to helping shipping customers on carbon-neutralization.
Unlike diesel fuel or other MGO, LNG is carried as a boiling liquid, and is a cryogenic liquid at temperatures of about -162°C (-259°F). In liquid form, natural gas occupies 600 times less volume that in a gaseous state, making it easier to transport over long distances and enabling a large storage capacity to be achieved in a relatively small space.

Purification and Liquefaction

1. Purification

Before liquefying nature gas, there are several compositions need to be filtered or removed. Such as heavy metals, sulfur and sulfides, carbon dioxide, water, heavy hydrocarbons, etc.

– Acid gas (CO2, H2S and other acid gases) removal: chemical absorption, combined absorption, amine liquid absorption (such as MDEA, DIPA); Sulfinol process (Sulfinol-D, Sulfinol-M)

– Water removal: solid adsorption method, molecular sieve, 4A.

– Removal of heavy metals: solid adsorption, activated carbon.

– Heavy hydrocarbon removal: freezing method, adsorption method, etc.

2 Liquefaction

Natural gas liquefaction refers to transforming natural gas from a gaseous state into a liquid state through cryogenic methods. There are three basic liquefying technique: Cascade refrigeration, MRC and Expander based liquefaction.

Any upgraded technology is for increasing single-series production capacity, reducing energy consumption, improving thermodynamic efficiency, and improving reliability are the development directions of natural gas liquefaction technology. The most advanced liquefaction technology combines three basic liquefaction process technologies with the actual conditions of raw natural gas. Combine and optimize to form a composite process technology based on mixed refrigerants.

The earliest plants consisted of fairly simple liquefaction processes based either on cascaded refrigeration or single mixed refrigerant (SMR) processes with train capacities less than one million tonnes per annum (MTPA). These were quickly replaced by the two-cycle propane precooled mixed refrigerant (C3MR) process developed by Air Products and Chemicals Inc. (APCI). This process became the dominant liquefaction process technology by the late 1970s and remains competitive in many cases today.