(375a) Systematic Design of An Acetaldehyde Process

Acetaldehyde is an important intermediate chemical. It is a volatile and flammable liquid being miscible in common organic solvents (e.g. benzene). Acetaldehyde can be synthesized by various methods; these include the partial oxidation of ethanol or ethylene, the hydration of acetylene or the dehydrogenation of ethanol. The partial oxidation method uses an expensive catalyst (silver based) and high reaction temperature while the hydration of acetylene involves the use of mercury as a mercuric complex which is a toxic material. Thus, the dehydrogenation of ethanol has attracted much attention as one of the preferred methods for producing acetaldehyde. This method uses only one reactant, ethanol, which can be synthesized from more abundant resources such as fermentation of agricultural products. Additionally, the co-product of this reaction is hydrogen, which can be used as energy source for fuel cells. Therefore in this work, which was done in an MSc Process Design course conducted at DTU, an acetaldehyde chemical plant is systematically designed using the hierarchical decomposition for process synthesis, having a total production of 1 x 105 metric tonne/yr. Of interest in the proposed design is the separation section, where the product purity of 99 mol % Acetaldehyde is achieved with 2 distillation columns where typically it has been achieved with 3. Sizing and costing base case calculations are also included due to its relevance and the plant is estimated to repay itself in approximately 4 years, having a total base case cost of approximately $32 MM being located in Trinidad. Heat and mass integration for the base case design is explored and optimization of the ethanol feed is investigated since the IRR is most sensitive to changes in the feed price. Finally a crude environmental impact is performed showing that the plant has a Potential Environmental Impact of 17805.9.