Pressure swing adsorption plant for recovery of materials from gases, removes e.g. polar solvent, especially water from process gases for re-use and releases benign emissions into environment

摘要

A hydrophobic molecular sieve is used for adsorption. Its polar potential derives from loading with a set quantity of polar material, the binding of the product gas resulting exclusively from van der Waals forces. An Independent claim is included for corresponding equipment carrying out the process. Preferred features: Desorption is by evaporation under microwave heating. The molecular sieve resists microwaves, not itself undergoing significant heating. This is treated with steam and pressure-compensating gas, e.g. nitrogen or water, its saturation and temperature corresponding with the process gas. This prepares the zeolite for polar binding. Desorption commences with pressure reduction using a vacuum oscillator (see later under pressure oscillator). After pressure reduction to correspond with the water boiling point under conditions in the molecular sieve, evaporation is completed in a second stage, when microwave energy is supplied. The adsorber is a fixed bed, through which the gas is forced by a blower under pressure. It is de-sorbed by pressure reduction and/or blowing-off using dry nitrogen. Desorption takes place under the critical evacuation temperature, controlled from the boiling point of water, at which the water still in the adsorption isotherm. The product gas, however, is already in the desorption isotherm. The molecular sieve is conditioned by a process heater, preheating the reactor and also adjusting the analog moisture of the process gas for the conditioned adsorption bed at the start of the process. The adsorption and desorption beds (interchangeable) are placed in chambers through which process gas flows, holding them at working temperature, such that no capillary condensation takes place in the molecular sieve. Adsorption takes place in a pressure swing plant or a reactor with thermally driven fixed beds or rotor fixed bed system. For desorption a pressure oscillator using four reduced pressure buffer vessels and a vacuum pump, is used, operated by a system of synchronized valves.