PROCESS DEVELOPMENT

PROCESS DEVELOPMENT


BUTANES RECOVERY

An Expanded Polypropylene (EPP) manufacturer whose production process was at the time based on a license from a European multinational corporation approached Pro-Tech with an interesting problem. Their process used as blowing agent a mixture of butanes (normal and iso), which were fed in liquid phase under high pressure to a batch reactor. At the end of the process the reactor contents was discharged into a let-down vessel at atmospheric pressure, causing sudden expansion of the polypropylene resin due to the vaporization of the butanes mixture, which by its turn was sent to a flare. Due to the high cost of butanes in Brazil, as well as the constant problems related to the efficiency of flaring, the company initially sought support with the licensor in order to minimize the loss of butanes. The licensor had no interest in changing their process, but allowed the company to search for a local solution. Thus, they hired Pro-Tech with the challenge of developing a process for butanes recovery. After studying numerous alternatives, based on various technologies (absorption, adsorption etc.), Pro-Tech ended up designing a process based compression and expansion with self-cooling steps, comprising also the pre-treatment of the gases (for water vapor removal) and intermediate steps for removing incondensables (mainly nitrogen). At the end of the Conceptual Design Pro-Tech received the green light to proceed with the subsequent phases of Basic Design and Detailed Design, at the end of which economic feasibility studies showed the viability of the process. Finally, the company decided to implement the project, where Pro-Tech coordinated the electro-mechanical assembly. A recovery rate of more than 75% of the butanes mixture fed to the process was achieved, also eliminating the need for flaring.