This unit operation simulates transport of bulk solids using a belt conveyor.
● Solids Transport by Belt Conveyor Procedure
If the volatile component evaporation is not ignored, the component material balances are done based on the evaporation percentages of pure components that are set as volatile. For each non-volatile pure component, the mass flow rate in the product stream is set equal to the liquid/solid mass flow rate in the feed stream, and the mass flow rate in the vapor stream is set equal to zero. For each volatile pure component, the mass flow rate in the vapor stream is calculated by multiplying the liquid/solid mass flow rate in the feed stream by the evaporation percentage, and the mass flow rate in the product stream is set equal to the remaining mass flow rate after subtracting the evaporating mass flow rate from the liquid/solid mass flow rate in the feed stream.
The evaporation percentages are either specified by the user or calculated based on the specified ‘Final LOD’ value. That is the loss on drying (LOD) of the dried product stream. A stream’s LOD is calculated as the ratio of total liquid mass flow rate to total liquid/solid mass flow rate for that stream. If a pure component appears in the liquid/solid phase of the feed stream, then that liquid/solid phase is considered either liquid or solid depending on whether that component is set as volatile or not. The ‘Initial LOD’ (i.e., the LOD of the feed stream) is first determined by dividing the total liquid mass flow rate of the feed stream by the total liquid/solid mass flow rate of that stream. Then, the total solids mass flow rate of the feed stream (which is the same as that of the product stream) is calculated as (1-Initial LOD). If the evaporation percentages of volatile components are set by the user, the total liquid mass flow rate of the product stream is calculated by summing up the individual liquid/solid mass flow rates of all pure components that are set as volatile. Then, the ‘Final LOD’ can be calculated by dividing the total liquid mass flow rate of the product stream by the total liquid/solid mass flow rate of that stream. If the ‘Final LOD’ is specified, then the program assumes that all volatile components have the same evaporation percentage, and that percentage is calculated as 100 (Initial LOD-Final LOD) / Initial LOD / (1-Final LOD).
If the heat losses to the surroundings are ignored, the exit temperature is set equal to the feed stream temperature. If they are not ignored, the user may specify a lower exit temperature than the feed stream temperature (but higher than the ambient temperature that is specified at the flowsheet level) to account for heat losses to the surroundings.
If Design Mode, the belt width is calculated by dividing the loading rate (MT/h) by the specific loading rate (MT/h-cm). If the calculated belt width exceeds the maximum, the program assumes multiple, identical units operating in parallel with a total belt width equal to the calculated. In Rating Mode, the user specifies the number of units and their belt width and the program calculates the specific loading rate. The user always specifies the belt length.
To account for electricity consumption, the user can either specify the power demand (in kW) or the specific power requirement (in W/(kg-h)-m). In the second case, the specific power requirement times the loading rate times the belt width yields the power consumption.
The interface of this operation has the following tabs:
● Oper. Cond’s, see Transport by Belt Conveyor: Oper. Conds Tab
● Power, see Transport by Belt Conveyor: Power 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