Page 273 - Chemical engineering design

248
CHEMICAL ENGINEERING

Figure 6.2. Capital Cost v. Capacity

Solution
Garret’s units are US dollars and US tons, and refer to 1987 (Chemical Engineering Index
quoted as 320).
1USton D 2000 lb D 0.91 tonne 1000 kg
So, 750 tonne per day D 750/0.91 D 824 US t/d
From Figure 6.2 the fixed capital cost for this capacity, for production from sulphur, is
6
13 ð 10 US dollars.
There are two possible ways to convert to UK costs:
1. Convert at the 1987 exchange rate and update using a UK index.
2. Update using a US index and convert using the current exchange rate.
1. In 1987 (January) the rate of exchange was $1.64 D £1, and UK and US cost can be
taken as roughly equivalent.
13 ð 10 6 6
1987 cost D D £7.93 ð 10
1.64
Updating this cost using the index published in Process Engineering (basis 100 at end
1990)
Index 1987 (January) D 78
2004 (January) D 154 (basis adjusted to 1990)
154 6
6
So, capital cost of plant early 2004 D 7.93 ð 10 ð D £15.67 ð 10
78
say, £16,000,000
2. Garrett quotes the Chemical Engineering Index for his costs as 320 (January 1987).