Simulation of a Hydrogen Peroxide Oxidation Tower

Examensarbete för masterexamen
Innovative and sustainable chemical engineering (MPISC), MSc
Larsson, Sara
Hydrogen peroxide is a strong oxidizing agent used in a great variety of applications. Its main usage is as a bleaching agent where the pulp and paper industry dominates. One of the world’s producer of hydrogen peroxide is Nouryon, who produce about 4% of the market volume. The primary way of producing hydrogen peroxide today is by the cyclic hydrogenation and autoxidation of anthraquinones (usually referred to as the AO process). The most commonly used raw materials for this process are hydrogen produced by steam reforming and air. With the current technical development, it is expected that electrolyzers producing green hydrogen is going to be used to a greater extent in the future. If this were to be implemented in a hydrogen peroxide plant it would enable the use of the by-produced oxygen as a cheap raw material in the oxidation tower. Using this pure oxygen would in turn make it possible to use a higher concentration of air in the gas feed which could be utilized in a smaller oxidation tower and with smaller ancillary equipment. This is therefore interesting since it may lead to lower investment and operating costs. This work has been done for Nouryon with the purpose to set up a simulation tool to be used for simulation of a hydrogen peroxide oxidation tower. The aim was also to use this simulation tool to investigate how different tower designs and operating conditions may affect the size and operating conditions of the tower. The project has successfully resulted in a simulation tool set up in the process simulation software HYSYS v12.1. The simulation tool consists of a kinetic model for the oxidation reaction and a flowsheet setup representing the oxidation tower. The model was designed and successfully validated by the use of reference data from multiple oxidation towers. The simulation tool has been used to simulate the operation of a hydrogen peroxide oxidation tower with higher inlet oxygen concentrations, lower oxygen excess and higher operating pressure. It has also been used to simulate an oxidation tower with recirculation of the off-gas. From these simulations it have been concluded that it is possible to operate the oxidation tower with a higher inlet oxygen concentration with the drawback of getting a higher outlet oxygen concentration. The results have suggested that this higher outlet concentration may be decreased by the operation with lower oxygen excess or recirculation of a part of the exhaust gas. As expected, the simulations have implied that the use of a higher oxygen concentration indeed should make it possible to reduce the oxidation tower size and still maintain the same productivity of hydrogen peroxide. Simulating the tower with a higher pressure has implied that it may also be possible to use an increased pressure to reduce the required tower volume. It has also been proposed that a higher pressure may be used to increase the productivity of a tower of a certain set size.
hydrogen peroxide , oxidation tower , AO process , simulation , HYSYS
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