(675a) Feasibility of Demand Response in the Chemical Industry

In the field of power generation, the aim is to increase the part of renewable energy. This brings an increase in fluctuations in power supply, which leads to a higher need for adaptability, meaning more flexibility in production and consumption of electricity. Load changes in energy-intensive industries as seen in the chemical industry would be a way to provide this. In the joint project ChemEFlex the feasibility of demand response in Chlor-Alkali-Electrolysis (CAE) as well as in other electrochemical processes of the chemical industry is analyzed. In this work, two processes with different levels of development were studied by evaluating suitable operating parameters and their tolerable limits.

The commercialized process for the electrohydrodimerization of Acrylonitrile (ACN) to Adiponitrile (ADN) was the first case considered suitable for further studies (Fig. 1). Adiponitrile is an intermediate in the production of Nylon. Worldwide the production rate of ADN is around 1,31 Mio. t/a, of which 300.000 t are made through cathodic hydrodimerization. This makes the so-called Monsanto-Process the most important electroorganical synthesis. An advantage of this process is, that it does not need a membrane, which makes it very attractive for demand response because this bottleneck in flexibility options has not to be considered.

The second case is the piloted process of the electrohydrodimerization of Formaldehyde to Ethylene glycol (Fig. 2). Ethylene glycol nowadays is almost exclusively made from direct oxidation of Ethylene, followed by hydrolysis of Ethylene oxide. Even though this process has a poor selectivity and is high in energy consumption, the use of mineral oil results in a very low price. Still, with increasing prices for crude oil and the additional profit from the control energy market, the electrochemical process could be a good alternative. Looking at the high production rates for Ethylene glycol, this could be the third-largest electrochemical process after Aluminum production and CAE.

Experimental section

Two experimental plantswere built in a laboratory scale ^{[1], [2]} to test the application of demand-side management. The changes in selected parameters like aging of electrodes, product quality, etc. are documented and evaluated while various flexibility profiles (load changes in seconds or minutes, adapted to the requirements of the control energy market) were applied.

Experiments were carried out in Microflowcells by ElectroCell AB (Sweden). For the Monsanto-Process the effects on an undivided cell were studied, whereas for the synthesis of Ethylene glycol, a Nafion 324 membrane was used for separation.

References

[1] N. L. Weinberg, D. J. Mazur, J. Appl. Electrochem., 21 (1991) 895 – 901.

[2] K. Scott, B. Hayati, Chem. Eng. Sci. 45, 8 (1990) 2341–2347.