Control of combustion Emissions Flashcards
(29 cards)
main reason NOx is considered an environmental problem
it initiates reactions that result in the production of ozone and acid rain
Ozone and acid rain can
damage fabric, cause rubber to crack, reduce visibility, damage buildings, harm forests and lakes, and cause health problems.
The principal nitrogen pollutants generated by gas fired equipment are
nitric oxide (NO) and nitrogen dioxide (NO2), collectively referred to as NOx
What is the majority of NOx produced during combustion and what percent
The majority of NOx produced during combustion is NO (95%)
Once emitted into the atmosphere what happens
NO reacts with volatile organic compounds (VOCs) to form NO2. It is NO2 that reacts with other pollutants to form ground-level ozone, a major component of smog.
N and O break apart from ultraviolet light causing and combine with VOC
Examples of VOC
aldehydes and ketones
Volatile organic compounds are compounds that have
high vapor pressure and low water solubility
VOCs typically are
industrial solvents, such as trichloroethylene; fuel oxygenates, such as methyl tert-butyl ether (MTBE); or by-products produced by chlorination in water treatment, such as chloroform
Are VOC higher indoor or outdoor
10 percent more indoor
One way to lessen the production of NOx from a burner is to
reduce the flame temperature by adding non-reactive gases such as carbon dioxide, nitrogen, steam or any other inert gas into the burner.
By adding about 10% of flue gas into the flame, the temperature will be reduced by
about 7 percent
Reducing flame temp can reduce Nox by what percent
50
The FGR ducting connects where
between a special port on the burner air intake and a branch in the flue close to the boiler outlet – and, potentially, a fan – with the flow of flue gas being modulated by a damper
Why insulated duct for FGR and why need draining port
to reduce condensate formation and includes condensate drainage points in the duct, preferably adjacent to the burner inlet
What can increase as NOx decreases
CO
What the newest strategy for NOx control.
Ultra-Lean Premix
Adding Water or steam injection is called what
flame quenching
Water or steam injection can reduce NOx up to what percent
80
What percent of efficiency is lost when using flame quenching
3-10 percent
NOx reduction by converting them into nitrogen, water, and carbon dioxide is called
Selective Catalytic Reduction (SCR)
SCR systems can reduce NOx emissions by what percent
90
Which system uses a catalyst and a reductant
SCR
What is the reductant
ammonia or urea
a process used to reduce nitrogen oxides (NOx) emissions from stationary sources, such as power plants and industrial boilers
Selective Non-Catalytic Reduction (SNCR)
