Combustion Plant - an Example

Combustion plant - an example

 

 

PROBLEM

The fluctuations of the coal calorific value should be minimized before the combustion.The combustion plant could use three different types of coal (A, B and C). The calorific values of the representative samples have been examined in a lab and are presented ni the following table:

Type	Calorific value [kJ/kg]
	Sample No. 1	Sample No. 2	Sample No. 3
A	6700	6490	6910
B	8375	8090	8650
C	7535	7765	7305

This fluctuation should be minimized through achieving an optimal mixture of this components. The mean calorific value of the mixture should be 7830 kJ/kg.

 

SOLUTION

All the measurements and constraints listed above are entered in the MIX++^® application. The following table shows percentage ratios of components in mixture, as well as mean values and standard deviations ( S_n-1 ) of all components in comparison to the mixture, as obtained from a successfully finished computation:

 

Type	mean calorific value [kJ/kg]	stand. deviation  Sn-1 [kJ/kg]	percentage [%]
A	6700.0	210.0	12.25
B	8371.7	280.0	47.48
C	7535.0	230.0	40.27
Mixture (MIX)	7830.0	164.07	100.00

 

The following probability distribution diagram is constructed under the assumption that calorific value of the components is distributed according to normal Gaussian distribution:

 

 Calorific value - probability distribution diagram

 

As these diagrams reveal, the standard deviation of the mixture is considerably smaller then the standard deviation of any of the components in the mixture.