Jozsef M. Berty

THERMAL STABILITY ANALYSIS OF THE LIQUID PHASE METHANOL SYNTHESIS REACTOR

ABSTRACT The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H2-rich and CO-rich syngas respectively, were used to experimentally verify the “slope” and “dynamic” critria in a three-phase fixed bed recycle reactor. The liquid medium, witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapor phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics.

SIMULATION OF EXPERIMENTS FOR THE DETERMINATION OF THE THERMAL STABILITY CRITERIA FOR THE “UCKRON-I” TEST PROBLEM

Abstract Simulated recycle reactor results were approximated for a limited range using a bicubic function. Partial derivatives of the reaction rate with respect to conversion and temperature and the ordinary derivative with temperature were calculated by differentiating the cubic function. Derived stability criteria for a tubular reactor performance were tested using the simulated results and good agreement was found. Some actual experimental data published earlier were also checked with this evaluation method and found to match the calculated results.

PERFORMANCE COMPARISON OF LABORATORY AND COMMERCIAL REACTORS USING THE UCKRON-I REACTION SYSTEM

Abstract A reactor model which includes axial and radial mass and heat dispersion was developed to compare the performance of laboratory and commercial reactors for the UCKRON-I reaction system. The program for the model allowed selection of either the ideal gas assumption or the real gas assumption for estimating physical properties and fugacities of each component. The two dimensional model using ideal gas assumptions gave essentially the same coolant temperature, 485.5 K, for the onset of thermal instability for commercial reactors as published values obtained using one dimensional models. Use of real gas assumptions reduced the coolant temperature at which thermal instability occurred for the commercial reactor by about 3 K. The coolant temperature at which thermal instability occurred for the laboratory reactor was about 50 K lower for both ideal and real gases assumptions.