OCR Text |
Show The performance index, J, can be defined in terms of any measurable parameters of interest. For the purposes of active control demonstration, the performance index is defined as J = g(l1c)+ f([N0x]) (1) 1- 0.75. ( [N0xh% ) 4 f([NOxD = [N°x]limit (2) (1- 0.75)· [N°x]max - [N°xh% [NO] [NO] ; x 3% > x limit [N0x]max - [N0x]limit (_ ') 1/2 g(l1c) = l llc 0 ~clmin J (3) 100 Yo 11 c,min where [N0x]max and 11c.min are set according to the ranges expected for a particular burner geometry. The definition of the efficiency function term is such that an increasing reward (i.e., an increase in J) is applied as combustion efficiency increases. The purpose of the piece-wise definition ofJ{[N0xD is to impose a high penalty on J above [N0X]limit and a rapidly decreasing penalty (increasing reward) for measurements below this limit. In other words, the contribution fromj{[N0xD to J is high as long as the measured NOx concentration is below the specified limit. The value of [N0x]limit can have practical significance, such as the permitted NO" 'emission limit - for a particular burner application. Hence, a burner with perfect performance would yield a value of J equal to 1.0 (l1c = 100%, [N0x] = 0 ppm). The intention of this performance index is to provide a single variable (a function of the two variables of interest) that may be evaluated and searched in real-time by a computer, using specialized optimization techniques. The way in which the performance index is defined is specific to the particular burner configuration, and its emission character, under study. It should , not, in the form presented above, be used as a universal parameter for comparing the performance of different burners, but it may be useful in comparing the performance of different configurations of the same burner. 4 |