Process Synthesis, Modeling and Optimization of Continuous Cooling Crystallization with Heat Integration—Application to the Chilled Ammonia CO₂ Capture Process

Abstract

A systematic method is presented to design multistage continuous crystallization processes with heat integration. A general method has been applied to a specific case, namely the integrated absorption-based process for postcombustion CO2 capture in which solid formation is exploited. At first, a set of viable process flow schemes based on different equipment configurations for crystallization has been selected. Then, a rate-based model capable of describing the phenomena occurring during crystallization and dissolution of particles coupled with heat transfer has been developed for design and optimization purposes. Because of the broad design space and the interplay between unit operations, the mathematical model stands out as the key tool for the assessment of the process feasibility. Furthermore, a multiobjective optimization of the solid handling section has been performed, the aim of which is twofold: identifying optimal operating conditions and gathering information on the effect of and the synergy among the different design variables on the process performance. The results are evaluated on the basis of key performance indicators such as productivity and specific energy penalty, as well as of the particle size distribution of the crystals obtained during crystallization.

Estimating speciation of aqueous ammonia solutions of ammonium bicarbonate: application of least squares methods to infrared spectra

“…After the equilibrium composition is found, eqn (9)-(12) are consulted to verify the presence of any solid phase. If one or more solid phases are formed, the corresponding equationIJs) must be solved together with eqn (1)- (8).…”

“…As a consequence of the equilibria of eqn (1)- (8), when comparable amounts of nitrogen and carbon are present in the system (ζ ≈ 1), the equilibria of eqn (4)-(5) leads to mildly alkaline solutions in which the ammonium and bicarbonate ions are the main species present (see sec. 5.6).…”

“…Ultimately, this work paves the way for the estimation of the crystallization kinetics of ammonium bicarbonate in aqueous ammonia solutions essential for the design and control of solid formation in ammonia-based CO 2 capture processes. 7,8…”

“…7 In this process, the information about the phase equilibria and the kinetic effects of chemical reactions and mass transfer are key for the design and optimization of a continuous crystallization section fully integrated with the rest of the capture plant. 8 Retrieving crystallization kinetics of BC for this system is complicated by the high volatility of the solutes, 9 i.e. NH 3 and CO 2 , and requires the information on the speciation of the solution for the computation of the driving force of the crystallization process, i.e.…”

Recent Progress in Continuous Crystallization of Pharmaceutical Products: Precise Preparation and Control

“…Configuration A exploits an MSMPR crystallizer for the final crystallization step, while configuration B uses scraped-surface heat exchangers. Reprinted from ref . Copyright 2018 American Chemical Society.…”