Membrane separation is a technology that uses separation membranes as the core for the selective separation, concentration and purification of substances. The basic principle is to use the different rates of dissolution and diffusion of each gas component in the separation membrane at a certain pressure, and therefore the different rates of permeation through the fibre membrane walls due to the partial pressure difference between the two sides of the membrane. The catalytic dry gas from large refineries, the fractionator top gas from gasoline hydrogenation units, the vapour stripper top gas from residual oil hydrogenation units and the PSA desorption gas, which contains a large amount of hydrogen and also many hydrocarbons of C2 and above, will affect the desorption of the adsorbent if they enter the PSA hydrogen extraction unit directly. One solution can be to first remove most of the hydrocarbons by pretreatment with membrane separation and concentrate the hydrogen to 90% (V) or more. This protects the adsorbent in the PSA small air separation unit behind and also greatly improves the hydrogen yield of the product. The disadvantages of membrane separation for pre-treatment in PSA hydrogen extraction small air separation units are that the gas itself needs pre-treatment such as de-oiling and dehydration before entering the membrane separation, the gas entering the membrane separation needs a certain pressure, the operation of the membrane separation needs to be warmed up to above 80°C and the concentrated hydrogen has a low pressure and needs to be pressurised again before entering the PSA small air separation unit.
The intelligent workshop of Dear has applied a large number of innovative technologies and air separation unit and air separation plant in the whole manufacturing process from raw material storage to product production and finished product inlet and outlet, and has obtained a number of national patents.
