Industrial furnaces, built for thermal processes, can be divided into two parts, separated by a radiation shield. In the lower part of a furnace, the fire box or radiation section, heat is transferred by radiation. In the upper part, called the convection section, heat is mainly transferred by convection.

The computer program can be used for heat transfer calculations in the convection section. During the practical work the program is changed from a single bank calculation program to a flowsheet oriented program.

In the new version of the computer program, the user can define a flowsheet,input the geometry of the banks, and physical properties of the flows. The program then will calculate the flowrates and temperatures of the other streams, and generates a bank performance report for all banks.

Blocks which can be used in the flowsheet are:

• MIX-block, used to mix two flows.
• SPLF-block, used to split one flow in two other flows. If two flows are fixed, the third can be calculated.
• SPLP-block, also splits a flow. The difference is that only one fixed flow is needed, together with a split percentage.
• BNK-block, this block represents a bank of tubes in the convection section of a furnace. All tubes in one (logical) bank must have the same geometry. The block generates a complete bank performance report.
• CTRL-block, ctrl blocks are not yet available in the program. They will be added in the future, to control iterations in the flowsheet calculation.

The program is provided with extensive error checking and diagnosis facilities which will direct the user in case of erroneous input or wrong specifications.

Conclusively, the program has turned into a powerful and reliable check-rating tool. It is relatively easy to handle by inexperienced computer users, and offers a strong potential for future extensions.