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[Sukhbir]

Facing a constraint in increasing the fired duty of the burners in a NHT heater for refinery. The furnace has 4 burners with a present heat release rate of 1.20 Gcal/hr against rated fired duty of 1.5Gcal per hour . The burners were designed for natural gas case. However, in the present case, the actual fuel composition is different from the design and is having higher percentage of hydrogen . With this fuel composition the burner tip pressure reaches 2.8 kg against 1.41kg at flow of 710 Nm3/hr. The typical operating parameter of the furnace are as mentioned below: Furnace flow rate =40 MT/hr ( 72 % of the rated case for the furnace) CIT = 228degC. COT = 310 deg C. FG flow = 680 Nm3/hr. FG header pressure = 3.3 kg/cm2g. Burner tip pressure = 2.4 kg/cm2g. FG C/v op = 70 % Max Convection zone temp = 270degC (Max allowable 340 degC) Max Radiant zone temp = 400 degC ( Max allowable 500 degC) Fuel molecular weight:13.5 Calorific value: 11200 Kcal/kg All the parameters of the furnace are within the limit but they are facing the issue of increasing the firing rate at burners due to Fuel flow limitation. The total flow through the burners is not increasing beyond 680Nm3/Hr. Can someone advise what to do?

[AlertO]

Hi Sukhbir

 

Changing fuel composition normally affects on the burner performance. For example, the increase of Hydrogen ratio in your NG leads to lower heating  value.  Maybe your burner system haven't adjusted properly and the existing control system still performs based on your original design. Attaching your existing control system will be helpful to us here.