Flexible and economical operation of chlor‐alkali process with subsequent polyvinyl chloride production

Abstract

Demand response (DR) can compensate for imbalances in variable renewable energy supplies. This possibility is particularly interesting for electrochemical processes, due to their high energy intensity. To determine the technical feasibility and economic viability of DR, we chose the chlor-alkali process with subsequent polyvinyl chloride production, including intermediate storage for ethylene dichloride. We estimate the maximum possible cost savings of implementing load flexibility measures. A process model is set up to determine the system characteristic. Subsequent optimizations result in the facility's best possible dispatch depending on additional and minimum power load, storage volume, and cost of a load change. Real plant data are used to specify model parameters and validate the system characteristic and the plant dispatch. An economic evaluation reveals the economic advantages of efficiency and flexibility. The approach can be used to analyze the DR potential of other chlorine value chains or facilities with high electricity demand in general.

Assessing the Realizable Flexibility Potential of Electrochemical Processes

“…In combination with known costs for renewing degraded process equipment, this allows a good estimation of the costs per activation. Such an approach is illustrated by Hofmann et al, 19 who estimate the LCC for the CAE. Their approach will also be applied in Case Study 3.…”

“…Global optimal solutions of such nonlinear optimization problems (NLP, MINLP) are often impossible to determine within reasonable time limits for such large time horizons. 62 Instead, the operation schedule can be obtained using a simplified model of the load curve as is the case for the model derived by us 19 and used in this contribution. Such a model is derived by solving a stationary model of the plant at varying load.…”

“…This model was used to determine the operating characteristics of the process and to obtain a load-dependent function of the DCE production. A complete description of the process and the operation scheduling model as well as the discussion of the obtained results can be found in Hofmann et al 19 Following the results for the technical potential, we assumed a maximum load of P max = 1.05 P 0 and P min = 0.75 P 0 . In this case study, we chose to only participate in the day-ahead market, which is described in Section 3.4.2, to illustrate our methodology.…”

“…As this information was not available at that time, specific LCC of € 5000 per full load cycle were derived based on theoretical considerations. 19 The results of the optimal operation scheduling are shown for both years in Table 5. The optimization was also carried out with specific LCC of € 0 per cycle to analyze their impact on the load profile; that is, load changes do not cause additional costs.…”

“…In contrast, the annual LCC in the corresponding cases amount to only 15−16% of these savings. We refer to Hofmann et al 19 for a more comprehensive discussion of the influence of the DR parameters and the LCC as part of a sensitivity analysis.…”