Verbal Modeling Anchors: Manganese  Matt Morabito Jamie Polan

Process Statement: Vaporized product enters a condenser, is cooled by cooling water, and leaves as a liquid. The liquefied product is stored in a jacketed tank, where refrigerant is used to keep the temperature low, and the product liquefied. The liquid product can be sold for $6/gal. The cooling water is provided by the plant and the exiting water stream is fed to a pond, so cannot exceed 35°C to avoid damage to the habitat. The refrigerant is recycled from another process and can be used again elsewhere. The storage tank has a maximum pressure of 5 atm, and volume limit of 5,000 gal. 2

Verbal Modeling Process 1) Describe the Process Condense product stream using a condenser Store liquid product in a refrigerated storage tank 2) Identify Process Objectives and Constraints Objective – Obtain liquefied product to sell at $6/gal Constraints Operational – Storage tank volume limit Safety – Storage tank pressure limit Environmental – Exiting water stream temperature limit 3) Identify Significant Disturbances Fluctuations of: ambient air temperature, feed temperature, cooling water temperature, refrigerant temperature, flow rates 3

Verbal Modeling Process (con’t) 4) Determine Type and Location of Sensors Temperature sensor – exiting water stream Temperature sensor – liquefied product storage tank Level sensor - liquefied product storage tank Pressure sensor - liquefied product storage tank 5) Determine the Location of Control Valves Feed inlet Cooling water inlet Refrigerant inlet Pressure release on storage tank 6) Perform a Degree of Freedom Analysis Number of manipulated streams – 4 Number of control objectives and control restraints - 4 DOF = 4 – 4 = 0 4

7) Energy Management Cooling water removes the heat from the product stream Refrigerant keeps the temperature of the liquefied product low 8) Control Process Production Rate and Other Operating Parameters Entering product stream valve → product flow rate Entering cooling water stream valve → outlet cooling water temperature Entering refrigerant stream valve → liquefied product temperature Storage tank valve → storage tank pressure 9) Handle Disturbances and Process Constraints Ambient air, cooling water, and feed temperature fluctuations Detected by: temperature sensor on the exiting cooling water stream Affects: valve on the cooling water stream inlet Refrigerant temperature fluctuations Detected by: temperature sensor on the storage tank Affects: valve on the refrigerant inlet Product flow rate fluctuations Detected by: temperature sensor in the storage tank Affects: valve on the product feed stream 5 Verbal Modeling Process (con’t)

10.) Monitor Component Balances Accumulation and loss of material - neglected 11.) Control Individual Unit Operations The condenser is fully controlled, with the valves on the inlet stream controlling the temperature and flows of products and cooling streams 12.) Optimize the Process DOF = 0  cannot optimize further 6