Limedas PEMS

Predictive or Parametric Emissions Monitoring Systems (PEMS) is an alternative approach to CEMS (Continuous Emissions Monitoring) for Environmental Control and air quality monitoring of Stationary Sources that uses mathematical and computer modelling techniques for emissions estimation and management. There are two types of PEMS that are available. The first one, uses first principles (fundamental concepts, methods and formulas, for example of thermodynamics or the ideal gas law), and applies them to the operating parameters. This approach requires deriving and solving complex mathematical equations and is often limited by assumptions and constraints, as there is no certain way to determine emissions based on only operating parameters of the smoke stack. The second category also uses the operating parameters, such as temperature(s), pressure(s), fuel flow rates, and oxygen level(s), attempts to build a profile or pattern of past emissions behavior and uses it if for estimation going forward. This is where Limesoft developed and offers a PEMS software solution, also called a statistical-hybrid PEMS model, that uses the combination of CEMS and process data collected in parallel, for statistical regression analysis and modeling. There are different types of facilities, and for some of them such parametric measurement approach can be applied better than for others. For example, it can be harder to develop a PEMS model for a flare stack, rather than a boiler or a gas turbine that uses the clean natural gas fuel and operates within a consistent range. Also keep in mind that the environmental regulatory authorities see PEMS to be less accurate then CEMS and often would not allow installing PEMS, but force implementing a more accurate and reliable CEMS approach.