双塔天然气氦气回收工艺研究

Study on technology for recovering helium from natural gas by double-tower

针对现有天然气氦气回收方法存在的能耗高、流程复杂、氦气回收率低以及粗氦产品纯度低等缺点,提出了一种创新的天然气氦气回收方法。该方法采用双塔提氦工艺,特色在于氦气提浓塔和氦气回收塔均采用具有温度梯度的多股进料方式,氦气提浓塔和氦气回收塔部分塔底出料分别在主冷箱和氦气回收冷箱中升温后回流。通过对该流程进行特性分析发现,可以通过增加理论塔板数、增加吸收塔回流量、升高低温分离器温度等方法来提高氦气回收率。通过对该流程进行适应性分析发现,氦气回收率随着原料气中氦气含量的增多而升高;在相同制冷条件及其他条件下,较贫气质的氦气回收率要高于较富气质的氦气回收率。对于不同的气质,综合能耗都随着原料气中氦气含量的升高而增加,气质越富综合能耗越高。

The existing method for recovering helium from natural gas has the shortages of high energy consumption, complicated process, low recovery rate and low purity of crude helium products.An innovative helium recovery from natural gas method is proposed.This method adopts a double-tower helium extraction process, in which both helium enrichment tower and helium recovery tower adopt a multi-feed method with a temperature gradient.Part of the bottom output of helium enrichment tower and helium recovery tower are heated in the main cold box and helium recovery cold box, respectively, and then refluxed.Through characteristic analysis on this method, it is found that the recovery rate of helium can be improved through increasing the number of theoretical plates, increasing the reflux flow of absorption tower, and increasing the temperature at cryogenic separator.Through the analysis on the adaptability of this method, it is found that the recovery rate of helium increases as the content of helium in the raw gas increases.Under the same refrigeration conditions and other conditions, the recovery rate of helium from the poorer gas is higher than that from the richer.As for different natural gas, the comprehensive energy consumption in recovering helium increases with the increase of the helium content in the raw gas.