MODELING AND SIMULATION OF A NITRIC-ACID RECOVERY PROCESS

A nitric acid recovery process using composite distillation columns wa s modeled and simulated. The composite distillation columns consist of a multistage vacuum tower and an atmospheric pressure tower half of w hich consists of packed bed The vacuum tower and the atmospheric press ure tower were modeled by using equilibrium stage method and non-equil ibrium stage method respectively. The required thermodynamic propertie s for nitric acid solution were obtained from correlations based on ex perimental data Results of simulations showed good agreement with actu al plant data From the results of simulations it was found that the up per half of the atmospheric pressure column and the vacuum column, con sisting of plate column, can be modeled using equilibrium model, but t he lower half of the atmospheric pressure column, which are packed par ts, can be modeled effectively using non-equilibrium model. The non-eq uilibrium model developed in the present study showed good agreement w ith actual operaton data