Prepare for Fuel Gas Long

1 was called upon to conduct the review. Since the letdown steam rates are the key parameters that determine the benefits, my first question was how the steam letdown rates were estimated in the opportunity evaluation. This question implies On what production basis was the steam balance developed  

A process plant is in fuel gas long when fuel gas production is more than the consumption. When surplus fuel gas cannot be exported, it may have to be flared, which will undo energy improvements and also produce CO2 emissions to the environment. Fuel gas long could happen when energy efficiency improves. 

There is a real story of fuel gas long, which was caused due to the implementation of several large energy-saving projects. The fuel gas long scenario was not predicted in advance as the plant had a poor fuel gas balance. The plant fuel gas balance underestimated the production of refinery fuel gas but overestimated fuel 

The lesson learned from this painfrd event is that the plant fuel gas balance needs to accurately model the amount of fuel gas produced in individual processes as well as the amount consumed in individual fired heaters and boilers. The balance model should account for variations in feed rates and process conditions as well as weather changes. The variation could be very significant and thus modeling of variation in fuel gas production is a major challenge in building the plant fuel balances. 

The main feature of a good fuel gas balance is to be able to balance fuel gas to 97% closure across variations in feed and product slates, processing conditions, and seasons. For example, processing heavy feeds could have a significant impact on fuel gas production and hence the fuel gas balance. A similar effect occurs for dramatic seasonal weather changes. 

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