Abstract
    
      Within gas plant processing facilities; controlled volumes of gases are used to sweep the plant flare system as purge gases to prevent air ingress and protect the entire system from back fire events. The use of fuel gas in flare and vent headers for purging purposes results in environmental emissions as well as the losses due to burning such amount of fuel energy. Flare emissions can be in the form of COx or NOx when fuel gas burnt in the flare headers. These environmental and economic considerations encourage researches to reduce production of greenhouse gases as well as saving thermal energy. This act as driver for gas producing companies to find alternative ways to replace fuel gas purging by another safe and available sources. This paper studies the positive environment and economic impacts of using gas plant low purity nitrogen for purging flare headers. The replacement of fuel gas with nitrogen in purging the flare and atmospheric vent headers is one of the options currently being developed to reduce environmental impact. Usage of nitrogen eliminates the environmental emissions, where low purity nitrogen extracted from the plant nitrogen production unit utility systems. In case of the unavailability of the low purity nitrogen, the fuel gas purge stream will still be available to be operated as back up during upset scenarios. The study concluded that the total emissions will be saved estimated to be 23,469 Ton per year after replacing the fuel gas by nitrogen in purging; as well as saving a significant financial impact of fuel flared per year. The estimated cost saving is calculated to be 1,677,844 USD per year; given the price of the gas is 4.7 $/btu. Also the paper concluded the payback period for the replacement process of the fuel purge gas using nitrogen by 19.2 months.