Proper tuning of combustion parameters of existing heater is key to reduce the emissions.
Incomplete combustion, too low or too high excess air, may lead to the following increased pollutants:
|Consequence on emissions
|Higher CO and PM emissions
|Too low excess air
|Higher CO emissions
|Too high excess air
|Higher NOx and CO2 emissions
Our experts have the followings recommendations regarding the tuning of combustion parameters:
- On the operation side: adjust excess air properly
- Ensure proper air/fuel mixture to the heater
- Ensure uniform air/fuel mixture to all burners, keeping same openings for burners register and fuel valve as well as all burners tips clean
- Make sure oxygen analyzer is at proper location and check its reliability
- Avoid liquid carry over thanks to adequate fuel preparation. Otherwise, it will lead to improper combustion, potential burner gas plugging or even coke formation on the tips
- Avoid tramp air that will generally cause firing to be increased.
- Maintaining desired heater draft will minimize the air leakage
- On the fuel side: avoid liquid carry-over by providing a coalescer and/or heat the fuel to keep the fuel temperature high enough. The sizing of the header of fuel gas to various burners should be properly done to optimize its velocity avoiding liquid droplets formation and possible further condensation and coke formation.
- On the combustion air side: ensure that the distribution of air is uniform to all the burners. This is especially applicable in a forced draft (FD) application. To do so, Heurtey Petrochem Solutions recommends performing a CFD modeling to ensure equal air flow to all burners.
- Heater turndown operation, this may result in high CO formation due to improper air and fuel mixture at the burners:
- Shutting one or several burners may help due to a better combustion on the remainder burners
- Be sure to close air register of the OFF burners (except for very high temperature services), but keep the pilots on in order to ensure the ON burners have proper air in fuel mixture.
Heurtey Petrochem Solutions would be happy to help you define the best strategy for improving environmental performance of your fired equipment. Don’t hesitate to contact us for customized solutions.