煤制气中甲烷化余热利用集成串级吸收式制冷新工艺

A novel integrated cascade absorption refrigeration technology by using waste heat in CTG's methanation process

煤制气甲烷化过程中会产生大量的低温余热,这部分热量直接排放到大气,造成较大的能效损失、经济价值损失。将溴化锂吸收式制冷和氨吸收式制冷的串级制冷工艺集成到甲烷化过程中,利用低品位余热制冷,可制得-40℃的冷量用于低温甲醇洗,以替代部分常规的压缩式制冷。这样能大幅降低电耗,提高能效。以40亿立方米/年的煤制天然气为例,该串级吸收式制冷集成甲烷化过程中的低温余热用于低温甲醇洗单元供冷,减少压缩式制冷负荷16.2%,折合节省标煤1.8万吨/年,动态投资回收期1.7年左右。

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 m^3·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.