Heating

General Description

This operation models the increase in temperature of a continuous flow or batch stream. The heat is provided by an appropriate heating agent that is specified by the user.

Unit Procedure Availability

      Heating Procedure

Heating: Modeling Calculations

Energy Balance and Equipment Sizing

The energy balance is represented by the following equation:

HeatingEB.jpg 

eq. (A.313)

where:

      Q is the heating duty (kcal/h),

      U is the overall heat transfer coefficient (kcal/h-°C-m2),

      A is the heat transfer area (m2),

      ΔT is the log mean temperature difference in the system (the driving force) (°C),

      m is the mass flowrate of the stream (kg/h), and

      cp is the specific heat capacity of the stream (kcal/kg-°C).

U is always specified by the user and m and cp are always calculated based on the stream flow and composition. When the user specifies the exit temperature (equivalent to specifying the value of ΔT), the above equations are solved for Q and A. When the user specifies the value of Q, the above equations are solved for ΔT and A. If the calculated A exceeds the maximum heat transfer area, the program assumes multiple units operating in parallel with a total heat transfer area equal to the calculated.

In Rating Mode, the calculated heat transfer is compared with the specified and if it is smaller, the user is advised to increase the heat transfer area and/or the number of units.

Heating: Interface

The interface of this operation has the following tabs:

      Oper. Cond’s, see Heating: Oper. Conds Tab

      Labor, etc, see Operations Dialog: Labor etc. Tab

      Description, see Operations Dialog: Description Tab

      Batch Sheet, see Operations Dialog: Batch Sheet Tab

      Scheduling, see Operations Dialog: Scheduling Tab