Using the refrigeration capacity of LNG in regasification at air separation plants

BACKGROUND: An important task at present is the issue of optimizing the circuit solutions of the air separation plant in order to reduce either the cost of the installation or the specific energy costs per unit of product. Also, questions are increasingly being raised about the possibility of using the low-temperature potential of LNG in the process of its regasification. AIMS: The purpose of the work is to study the possibility of combining the processes of regasification and air separation, as well as to obtain calculation dependencies, based on which it is possible to draw a conclusion about the efficiency of such a solution in comparison with the traditional circuit of the air distribution unit. MATERIALS AND METHODS: In the course of work in the Hysys-14 software environment, three circuits of the air distribution plant with different options for switching on the LNG flow were simulated, for which the dependences of the nitrogen recovery factor and specific energy costs on the pressure in the cycle are given. RESULTS: The calculation results showed that the energy costs for nitrogen production are lower by an average of 59.75%, 50% and 46.75%, respectively, for the first, second and third schemes compared to the traditional scheme of air separation plant, and the recovery factor is higher by an average of 55%, 45% and 72.5%, respectively. CONCLUSIONS: The study showed that the use of LNG refrigeration capacity in the air separation plant process flow chart can significantly increase the recovery factor, reduce specific energy costs for the production of a unit of product, and also reduce the cost of the plant. The advantages and disadvantages of each scheme are considered, and possible areas of application of the obtained results are proposed.