Modeling the Energy Consumption of Chemical Batch Plants  Top-Down Approach

• Published in: Industrial & engineering chemistry research Vol. 42; no. 24; pp. 6135 - 6144
• Main Authors: Bieler, Patric S, Fischer, Ulrich, Hungerbühler, Konrad
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 26.11.2003
• Subjects: Applications of mathematics to chemical engineering. Modeling. Simulation. Optimization; Applied sciences; Chemical engineering; Exact sciences and technology; Energy consumption; Chemical industry; Utilities; Scheduling; Chemical plant; Modeling
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie030230x

The aim of this work is the development of models describing the energy consumption of chemical batch plants. These models can then be used to forecast and optimize future energy consumption of the plants investigated. Three multipurpose batch plants, two multiproduct batch plants, and one monoproduct batch plant were analyzed. The utilities investigated were steam, brine, and electricity. In a first step, a top-down approach was used to investigate whether it is possible to correlate the overall energy consumption with the total amount of chemicals produced in a building. The results showed that the postulated model for energy consumption on the building level is suitable for monoproduct batch plants. For multiproduct and multipurpose batch plants, a good description of energy consumption was obtained only if the different chemicals produced had similar production processes or if the production mix stayed constant over time. The postulated model was not suitable for multiproduct or multipurpose batch plants that produce a large variety of different products. For these plants, further investigations on the apparatus level will be needed (bottom-up approach). The investigations on the building level showed that the base consumption of a production building (energy consumed by the completely functional building without any production going on) is large for most buildings and that it is highly dependent on the building specifications. Because of the significant base loads, the specific energy consumption per ton of chemicals produced is lower for higher plant usage, a finding that can be used for plant scheduling purposes. For space heating, general models depending on the air change rate and number of degree days were postulated and found to describe the measured data well.