Nitrogen plant emission

The first commercial appHcation of precious metals for the reduction of nitrogen oxides in power plant emission control was in 1989. W. R. Grace s... 

Ammonia Plants - New ammonia plants should set as a target the achievement of nitrogen oxide emissions of not more than 0.5 kg/t of product (expressed as NOj at 3%). Ammonia releases in liquid effluents can be controlled to 0.1 kg/t of product. Condensates from ammonia produetion should be reused. 

Power plant emissions result from the comhustion of fossil fuels such as coal, gas, and oil. These emissions include sulfur dioxide (SO,), nitrogen oxides (NO.,), particulate matter, and hazardous air pollutants, all of which are subject to environmental regulations. Another emission is carbon dioxide (CO,), suspected of being responsible for global warming. 

While the development of flue gas clean-up processes has been progressing for many years, a satisfactory process is not yet available. Lime/limestone wet flue gas desulfurization (FGD) scrubber is the most widely used process in the utility industry at present, owing to the fact that it is the most technically developed and generally the most economically attractive. In spite of this, it is expensive and accounts for about 25-35% of the capital and operating costs of a power plant. Techniques for the post combustion control of nitrogen oxides emissions have not been developed as extensively as those for control of sulfur dioxide emissions. Several approaches have been proposed. Among these, ammonia-based selective catalytic reduction (SCR) has received the most attention. But, SCR may not be suitable for U.S. coal-fired power plants because of reliability concerns and other unresolved technical issues (1). These include uncertain catalyst life, water disposal requirements, and the effects of ammonia by-products on plant components downstream from the reactor. The sensitivity of SCR processes to the cost of NH3 is also the subject of some concern. 

Selective catalytic reduction (SCR) catalysts are used for controlling nitrogen oxide emissions from power plants. The reducing agent is... 

What can be done to protect limestone and marble structures from this kind of damage Of course, one approach is to lower sulfur dioxide and nitrogen oxide emissions from power plants (Fig. 5.31). 

Postformation nitrogen oxide emission control measures include selective catalytic and noncatalytic reduction with ammonia, which between them are used by some 900 power station installations worldwide [51]. The catalytic removal methods are 70-90% efficient at NOx removal, but are more expensive to operate than the noncatalytic methods which are 30-80% efficient. Ammonia or methane noncatalytic reduction of NOx to elemental nitrogen is also an effective method which is cost-effective for high concentration sources such as nitric acid plants (Chap. 11). NOx capture in packed beds is less expensive, but this method is not particularly effective [23]. It is also not a very practical method either for utilities or for transportation sources. Two-stage scrubbing has also been proposed as an effective end-of-pipe NOx control measure. The first stage uses water alone and the second uses aqueous urea. 

The problem of nitrogen oxides emissions from nylon plants was mentioned previously. Mallinckrodt produces nitrogen oxides when it dissolves metals in nitric acid. By using hydrogen peroxide to oxidize the nitrogen oxides to nitric acid, it has eliminated 30 tons/year of the oxides and reduced its nitric acid use by 109 tons/year.208... 

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