Thermodynamic Process Synthesis, Using Simple Thermodynamic Tools to Assess and Design Processes

Speaker:

David Glasser, University of Witwatersrand, Johannesburg, South Africa

Date & Time:

April 14, 2008 - 1:00pm

Location:

601 CoRE

Thermodynamic Process Synthesis, Using Simple Thermodynamic Tools to Assess and Design Processes Chemistry and Chemical Biology
David Glasser, University of Witwatersrand, Johannesburg, South Africa 1:00 PM, 601 CoRE A chemical plant can in principle be viewed as an isolated entity. In order for this entity to operate it has to satisfy a mass balance, an energy balance and its entropy production must be not less than zero. This latter condition can be re-written in terms of a Gibbs Free Energy and this is shown to be a work balance inequality for the plant that has to be satisfied in order for the plant to operate. Thus making a plant operate successfully often becomes an exercise in how to put work into the plant. On the other hand putting in too much work becomes a source of inefficiency. These ideas are illustrated by examining a methanol production plant. It is shown that this plant can be viewed as a heat engine that is needed to supply the work needed to make the plant run. Furthermore it is shown that this work is not sufficient to make a commercial plant operate and the extra work is added via compression. The big advantage of the new approach is that one is now able to examine a plant at a very high level using only simple thermodynamic data, without needing all the detail of a normal design. One can then make decisions about the plant flow-sheet at very early stage of a project or alternatively identify the sources of inefficiencies in current plants that in the case of the methanol plant lead to increased carbon dioxide emissions. This thus becomes a very powerful systems tool for looking at flow-sheets in an integrated fashion.

Thermodynamic Process Synthesis, Using Simple Thermodynamic Tools to Assess and Design Processes
Chemistry and Chemical Biology

David Glasser, University of Witwatersrand, Johannesburg, South Africa
1:00 PM, 601 CoRE

A chemical plant can in principle be viewed as an isolated entity. In order for this entity to operate it has to satisfy a mass balance, an energy balance and its entropy production must be not less than zero. This latter condition can be re-written in terms of a Gibbs Free Energy and this is shown to be a work balance inequality for the plant that has to be satisfied in order for the plant to operate. Thus making a plant operate successfully often becomes an exercise in how to put work into the plant. On the other hand putting in too much work becomes a source of inefficiency.

These ideas are illustrated by examining a methanol production plant. It is shown that this plant can be viewed as a heat engine that is needed to supply the work needed to make the plant run. Furthermore it is shown that this work is not sufficient to make a commercial plant operate and the extra work is added via compression.

The big advantage of the new approach is that one is now able to examine a plant at a very high level using only simple thermodynamic data, without needing all the detail of a normal design. One can then make decisions about the plant flow-sheet at very early stage of a project or alternatively identify the sources of inefficiencies in current plants that in the case of the methanol plant lead to increased carbon dioxide emissions. This thus becomes a very powerful systems tool for looking at flow-sheets in an integrated fashion.

Giving to IAMDN

Thermodynamic Process Synthesis, Using Simple Thermodynamic Tools to Assess and Design Processes