Decision Sequence

Decision

Category

Decision Subject

Explanation

Level 1

Orientation

Specifer

Purchaser or A/E making the decisions for bid purposes

Level 2

Application

Electric, fossil, coal

Also applicable for gas turbines, incinerators, and cement kilns

Level 3

Process

NOx reduction

Can be used with both SCR and SNCR

Level 4

Location

SCR outlet

Measure ammonia slip but can also be measured in the stack after the scrubber or other equipment

Level 5

Pollutant

NH3

Ammonia which escapes SCR

Level 6

Product

CEM

Continuous emission monitor to measure ammonia after reaction with NOx

Level 6a

Type

Insitu

Big differences between measuring in stack and taking a small sample and conditioning and treating it

Level 6b

Type

Extractive

Extract sample, condition and measure

Level 7a

Principle

Laser spectroscopy

(TDL IR) 

Advantages: interference free, in situ or extractive and suitable for coal

Disadvantages: moisture interference, limited experience

Level 7b

Principle

Automated wet chemistry

Advantages: familiarity, quick set up and good for extractive periodic testing

Disadvantages: labor intensive, reagents