Self-heat recuperative dividing wall column for enhancing the energy efficiency of the reactive distillation process in the formic acid production process

Formic acid production through methyl formate hydrolysis has been shown to be energy and capital cost intensive, and its performance could be significantly promoted by process intensification. However, integration of reaction and separation exhibits a complex nonlinear behavior, which requires corresponding optimization and control to be effectively addressed before further industrial implementation. In the present work, optimization was first performed for a conventional reactive distillation (RD) process and reactive dividing wall column (RDWC) by coupling genetic algorithm and rigorous simulations, in which a user-defined model was incorporated to take kinetics into account. Although the results demonstrate that RDWC is inferior to RD in terms of economic criteria, it provides the basis for proposing new easy-to-operate configurations in the subsequent part 2 of this series. Then multiloop proportional–integral (PI) control structures and linear model predictive control (MPC) schemes were designed for the conventional RD process and RDWC, respectively. The performances of two control structures were compared subject to feed disturbance, by using quantitative indexes such as oscillation, settling time, overshoot, and integral of the squared error (ISE). The dynamic response validates that MPC outperforms classical multiloop control schemes and could tackle the excessive overshoot deficiency in PI control for both the conventional RD process and RDWC.

Section: Optimization For Conventional Rd Process and Rdwcmentioning

confidence: 99%

Optimal Design, Proportional–Integral Control, and Model Predictive Control of Intensified Process for Formic Acid Production. 1. Reactive Distillation and Reactive Dividing Wall Column

Yang

Han

et al. 2020

“…Sharma et al 3 employed a heat pump to further reduce the energy consumption of RDWC, and 8.4% total annualized cost (TAC) could be saved if vapor compression is used in a methanol recovery column and subsequent RDWC. Using the same basic process patented by Huang,4 Lee et al 5 employed a side-reboiler which integrated the condenser in the side rectifier and the column section below the reactive distillation section. The energy saving could reach 20.3% through sensitivity analysis optimization.…”

Section: Introductionmentioning

confidence: 99%

Optimal Design, Proportional-Integral, and Model Predictive Control of Intensified Process for Formic Acid Production II: Reactive Dividing Wall Column without Uncontrollable Vapor Split

Han

Yang

et al. 2021

A reactive dividing wall column (RDWC) integrates reactive distillation and multiproduct separation together, leading to the realization of process intensification. However, the reluctance to use it is due to the uncontrollable vapor split, which is self-regulated according to the flow resistance on each side of the partition wall. For some cases, the pressure of reaction and multicomponent separation is different, which results in an energy penalty if we directly integrate these units together, for example, formic acid (FA) production through methyl formate (MF) as presented in the part I of this series (Ind. Eng. Chem. Res. 2020, 59, 22215). To tackle these obstacles, a new reactive dividing wall column without the uncontrollable vapor split (NV-RDWC) by converting the bidirectional vapor–liquid thermal coupling to liquid-only transfer stream is proposed in this work. Optimization was first carried out by coupling the genetic algorithm (GA) and rigorous simulation. On the basis of the optimal solution, a detailed comparison was conducted between the conventional reactive distillation process, RDWC, and NV-RDWC, and the results show the superiority of NV-RDWC. Then two multiloop proportional-integral (PI) control structures and a model predictive control (MPC) for NV-RDWC were developed, respectively, to investigate their control performance. The dynamic response in the face of feed disturbance shows that MPC could give superior control performance for this complex coupled process.

“…Some academic publications − give more details on certain aspects of these manufacture routes, such as process development and simulation setup. Wang studied and reported kinetics of the MF hydrolysis using an ion-exchange resin as catalyst.…”

Section: Introductionmentioning

confidence: 99%

Design, Optimization, and Retrofit of the Formic Acid Process II: Reactive Distillation and Reactive Dividing-Wall Column Retrofits

Cunha

Rangaiah

Hidajat

2018

Formic acid (FA) is an important chemical with many applications in the industry. Nevertheless, its manufacturing process has not received much attention in the open literature. In Part I of this series (da Cunha et al., Ind. Eng. Chem. Res. 2018, 57, 9554−9570), FA process was simulated and optimized for the production of 98 wt % FA. Total annual cost (TAC) of the optimal base case process was 0.686 USD/kg. This process was then retrofitted via integration of two distillation columns into a dividing-wall column (DWC), but such retrofit was not profitable. Here, in Part II, FA process retrofit via reactive distillation (RD) and reactive dividing-wall column (RDWC) are investigated in detail. Results show that RD retrofit is not attractive as it increases TAC of the process. However, retrofit via RDWC is profitable, resulting in a thermal energy savings of 20.4% and a TAC savings of 0.020−0.042 USD/kg (by 3%−6%).