1.4: Input-Output Diagrams
- Page ID
- 101138
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- Create input-output diagrams
Input-Output Diagrams
These diagrams are considered to be the simplest of process flow sheets. In input-output diagrams, the entire process is represented by 1 block only. They usually only reference the main process streams in and out of a process.

text
Solution
text.
Consider an ammonia production process where 3 main streams of raw materials enter the process:
- 700 tons/day of methane
- 1590 tons/day of water
- 1650 tons/day of nitrogen
The process produces 2 main product streams:
- 2000 tons/day of ammonia
- 1940 tons/day of carbon dioxide
We can put together the following input-output diagram for this process:

Consider a process where toluene is fed into a process at 1000 kg/hr and hydrogen is fed at 82 kg/hr. The following reaction takes place in the process:
\[C_{7}H_{8} + H_{2} ➡ C_{6}H_{6} + CH_{4}\]
The reaction achieves 75% conversion and the products of the process are separated into 2 streams. The first product stream is benzene, exiting at 821 kg/hr. The second product stream is a mixed gas stream (including the unreacted reactants and by-products) exiting at 261 kg/hr. Draw an input-output diagram for this process.
Solution
Add example text here.

Our client wants to produce 360,000 tonnes/yr (800 million lbs/yr) of vinyl chloride monomer. We decide to use the following reaction pathway, which contains two reaction steps as follows:
\[C_{2}H_{4} + Cl_{2} → C_{2}H_{4}Cl_{2} (1)\]
\[C_{2}H_{4}Cl_{2} → C_{2}H_{3}Cl + HCl (2)\]
We gather the following information on the process:
Name | Formula | Molecular Weight (g/mol) | Price (USD/tonne) |
---|---|---|---|
Ethene | \(C_{2}H_{4}\) | 28.05 | 733 |
Chlorine | \(Cl_{2}\) | 70.91 | 240 |
Dichloroethane | \(C_{2}H_{4}Cl_{2}\) | 98.96 | 300 |
Hydrogen Chloride | \(HCl\) | 36.46 | 140 |
Vinyl Chloride | \(C_{2}H_{3}Cl\) | 62.50 | 750 |
Assume as well that our production costs are \(200\frac{USD}{tonne}\) of VC produced, and assume our VC production plant costs \(50,000,000 USD\) to build. Note these values usually depend on the size of the plant, location, and other factors.
Create an input-output diagram of the process.
Solution
Add example text here.
We know that one of the product streams will be 360,000 tonnes/yr of vinyl chloride. Hydrogen chloride is produced in a 1:1 molar ratio with vinyl chloride:
\[HCl = 5,760\frac{tonne-mol}{yr}*36.46\frac{tonnes}{tonne-mol}=210,000\frac{tonnes}{yr}\]
Similarly for ethane and chlorine, we get:
\[C_{2}H_{4} = 5,760\frac{tonne-mol}{yr}*28.05\frac{tonnes}{tonne-mol}=162,000\frac{tonnes}{yr}\]
\[Cl_{2} = 5,760\frac{tonne-mol}{yr}*70.91\frac{tonnes}{tonne-mol}=408,000\frac{tonnes}{yr}\]
From this and the information in the table, we get the following input-output diagram:
