Scaling process flowchart

Suppose you have balanced a process and the amount or flow rate of one of the process streams is n. You can scale the flowchart to make the amount or flow rate of this stream by multiplying all stream amounts or flow rates by the ratio n2/ni, You cannot, however, scale masses or mass flow rates to molar quantities or vice versa by simple multiplication conversions of this type must be carried out using the methods of Section 3.3b. 

TEST 1. What is a balanced process How do you scale a flowchart What is a basis of calculation ... 

Answers, p. 656) as directed, and draw flowcharts for the scaled processes. 

A basis of calculation for a process is an amount or flow rate of one of the process streams. If two or more stream flow rates or amounts ate given in the problem statement, they constitute the basis of calculation. If one is given, it may be assumed as a basis but it may also be convenient to assume another basis and then scale the flowchart to the specified value. If no flow rates or amounts are given, assume one as a basis, preferably an amount of a stream with known composition. 

The units of the mole fractions in the top product stream may be changed from mol/mol to Ib-raole/lb-mole, but their values remain the same. The flowchart for the scaled-up process follows. 

As a general rule, the combined feed to the reactor is a convenient stream to use as a basis of calculation for recycle problems when the stream composition is known. We will therefore temporarily ignore the specified methanol production rate, balance the flowchart for the assumed basis, and then scale the process to the required extent. In terms of the labeled variables, the problem statement will be solved by determining no, - oc, - sc, -Tsh. ip, and for the assumed basis, then scaling up no,... 

The engineer concerned with process design has to choose for a given dryer those conditions that enable the specified properties of the product to be obtained. The performance characteristics of alternative systems should also be assessed before the final choice of a dryer type. Almost always some small-scale tests are needed to determine the materiaTs drying characteristics required to predict the way in which the raw material would behave in the actual unit A flowchart illustrating the various steps needed to design a dryer is shown in Ref. [3]. 

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