Pinch Analysis Reveals Potential at Bowater's-Calhoun Tennessee Mill, 1999 Pulping Conference Proceedings

Bill Litzenberg

Bowater Inc.

Jasdev Gill & Theodora Retsina

American Process, Inc.

An energy audit using Pinch Technology was undertaken at Bowater’s Calhoun newsprint mill.

This is an integrated pulp and paper mill that produces newsprint, white and color, specialty forms and dried pulp with intermediate fibers of Kraft, TMP, groundwood and recovered waste papers.

The purpose of the study was to find the minimal theoretical thermal energy required to run the site and compare it to the actual energy used. Furthermore, the goals included the development of energy savings projects to bring the actual energy usage as close as practically possible to the minimal thermal energy target.

The study also took into account the TMP Expansion project now under construction that eliminates the groundwood plant and the planned conversion of an existing recovery boiler to a bubbling fluidized bed boiler to burn bark and sludge.

API engineers worked together with the mill personnel to define and model all process departments. The simulation was validated comparing the predicted results against mill data and was used to form the basis of further work.

The application of pinch technology revealed maximum theoretical steam savings of 27% of the energy currently used. Approximately half of the identified savings would displace purchased fossil fuels and the remaining savings would remove site-derived bark. There is no economic justification for the latter; therefore, the savings were limited to only 12% of the energy currently used. The study also made recommendations on how best to integrate the future TMP plant and the new BFB boiler with the existing mill operations.

The mill is currently looking at implementing many of the recommended projects and the work shows simulation models and Pinch Technology to be powerful analytical tools, which yield practical results.