Simulation of calcium acetylide and acetylene production

Abstract

Abstract Design simulation of a reactor for acetylene production from calcium acetylide and its purification in the gaseous phase is presented. Simulations were performed using the program ASPEN+ which is a very flexible and useful tool for the simulation and optimization of various types of chemical technologies including gas-liquid-solid systems. The first step of the acetylene synthesis, based on coal as the raw material, is the production of calcium acetylide. This substance is obtained from coke and limestone in an electric arc furnace at elevated temperatures. Raw materials used in this process contain relatively large amounts of impurities that are converted and entrapped in the desired product of the above reaction. Some of the impurities, e.g. metallic iron or its alloys, can be separated easily. However, most of the other elements present in the form of their compounds with calcium remain a part of “technical grade” calcium acetylide. Acetylene is commercially produced by the reaction of “technical grade” calcium acetylide with water under controlled reaction conditions in an inert atmosphere. Depending on the purity of calcium acetylide used, the produced raw acetylene contains a variety of admixtures that lower its quality. As a consequence, prior to its expedition to the customer, raw acetylene should be submitted to a down-stream processing that consists of the separation of basic and acidic pollutants present in acetylene by absorption. The final processing step is adsorption and/or freezing-out of water vapor from the purified acetylene stream. Besides acetylene, the reaction of calcium acetylide with an excess of water provides aqueous calcium hydroxide. In order to commercialize this byproduct, the content of water in the mixture should be lowered to the required level. In this contribution, development of a model of calcium acetylide and acetylene production as well as the simulation of these processes in ASPEN+ are presented. Simulation results of a realistic production line model correlate very well with the actual data from the technology used in Fortischem, a.s., Novaky, Slovakia.