Heat integration in regeneration process of molecular sieves including heat storages.

Abstract

Molecular sieves are materials often used in the petroleum industry, especially for the purification of gas streams and in the chemical industry for separating compounds and drying reaction starting materials. They are also used in the filtration of air supplies for breathing equipments. When saturated, the molecular sieve should be regenerated so that it can be used again. The objective of this paper is to study the heat integration possibilities in the process of regeneration and cooling of a molecular sieve using heat storages. We will be trying to find the optimum design of the heat integration network including heat storages and heat exchangers. This is done using a MILP (Mixed Integer Linear Programming) formulation of the multi period heat integration problem. The inputs of the algorithm are the temporal variation of the operational gas’ temperature and of its heat capacity over the whole cycle and the desired maximum number of heat storages to be used. The outputs of the algorithms are the heat storages temperatures, their capacities and the net heating and cooling energy demanded to satisfy all the energy needs of the process. The study will consider many simulations; in each the number of heat storages used is different. The results of each case will be shown and discussed and compared with the reference case, where all energy demands (heating and cooling) are satisfied using hot and cold utilities.

Keywords

• Heat integration,multi-period; heat storage; MILP formulation; regeneration of molecular sieves.

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