CFD Simulations Of An Inner Loop Cooling-absorption Tower

For the recovery of discharged ammonia gas in the chemical fertilizer industry, a type of inner loop cooling absorption equipment was designed. Compared with the common plate column, packed tower and plated-packing composite tower, the new equipment has very high absorption efficiency when there is a lot of reaction heat produced in the absorption process. It is comprised of sieve plates in the upper part and inner loop cooling-absorption components. Through laboratory tests and factory practices, the highly effective absorption mechanism the equipment was made clear to some extent. This dissertation is designed to investigate the dynamic behavior of fluid flow in the inner loop cooling-absorption components by numerical simulations,The two-phase flow continuity equation, momentum equation, turbulent flow equation near wall turbulent equation are established on the basis of the finite volume method for the cases of hollow tower, tube-filled tower, inner loop cooling-absorption tower. By theoretical analysis, the drag force equation is used for the source term of the momentum equation, the standard k-ε turbulent flow equation is used for the turbulence flow equation of the hollow tower and tube-filled tower, the RNG k-s turbulent flow equation is used for the turbulence equation of the inner loop cooling-absorption tower. The standard wall function method is used for the near wall turbulent flow equation in the calculation. The commercial CFD software FLUENT6.3is used for the computation. The GAMBIT, as the preprocessor of the FLUENT is used to build the physical model, mesh the model and sett boundary conditions of the hollow tower, tube-filled tower and inner loop cooling-absorption tower before performing calculations.The Euler-Euler two-phase flow model is used to perform the computations for the hollow tower, tube-filled tower and inner loop cooling-absorption tower in FLUENT6.3. The liquid-phase pressure distributions and the gas-phase velocity distributions in the hollow tower, tube-filled tower and inner loop cooling-absorption tower are determined through the computations. By comparison, it is concluded that the existence of the spiral elements in the tube makes gas and liquid turbulence intensify. Consequently, the gas-liquid interface get constantly updated, and eventually results in an increase of gas-liquid mass transfer efficiency in the inner loop cooling-absorption tower. This work can provide a guidance for the further investigations and designs of the inner loop cooling-absorption equipment in the future.