Crude heater inlet manifold deals with the liquid phase and a standard design is ok, assuming control valves or even orifices are balancing coil flows. Crude unit heater service is not a typical coking service and can tolerate some coil flow variations +/- 5 %, while focusing on firing...
As per my experience with fired heaters, snuffing steam should be included in this design; for example, to estinguish firebox fire in case of a hot oil tube rapture,.
Normally, steam impingement on the tubes and fibre blanket or refractory should be avoided.
As you mentioned there is no need...
During the fired heater stack gas testing benzene(C6H6)was surprisingly found(34 ppm). #6 fuel oil @ excess O2 of 5% was fired.
Contractor used the VOST sampling method from EPA Method 0030. Lab reported that the sample was diluted few times to bring VOCs on scale. Is EPA Method 18 better?