Methanation process in coal to synthetic natural gas (CTG) produces a large amount of waste heat. It will cause a huge loss of economic value and energy efficiency with this part of heat emitted into the atmosphere directly. LiBr absorption refrigeration and NH3 absorption refrigeration cascade refrigeration technology (CRT) is driven by waste heat from methanation process. CRT can produce-40℃ ammonia used in rectisol which can replace a part of compression refrigeration. Thus

it can reduce power consumption significantly and increase energy utilization efficiency. For example

CRT is integrated with methanation applied in a 4 billion m3·a-1 SNG plant. As a result

16.2% compression refrigeration load is substituted

equivalent to saving 18000 tons standard coal per year. The dynamic payback period is about 1.7 years.