[Alfredo Velasco]

If your reactor is a Partial-combustion type, one method is to change to a Total Combustion type.
 
For control of particules you can use a Electrostatic Precipitator located after the CO Boiler and before the stack.
 
Regards,
 

[Alfredo Velasco]

If your heater is a forced draft heater you must control the fuel/air ratio, so there is a need for a value of the combustion air: maybe this value can be obtained by checking the excess air at the bridgewall level or with a proper meter. Typical problem is how to regulate the dampers inside the air ducts.
 
If your heater is a natural draft heater, the air is not measured. You only work with the excess air measured at the bridgewall level.
 
Regards,
 

[Alfredo Velasco]

There are a lot of operational issues, one of them is the tube skin temperature. This temperature can be monitored by the color of the tube or with other devices like optical pyrometers, etc. Try to no be above the maximum tube metal of the tube because it will damage the tube permanently.
 
Other issue is to keep a proper air/fuel ratio by mean of the excess air. So be carefull about the fuel content in the flue gases. Natural or forced draft?
 
You can start the procedure by increasing the heat inside the firebox using only the pilot burners, then if more temperature is needed a main burner can be lighted.
 
There are typical procedures.
 
Regards,
 
Alfredo Velasco

[Alfredo Velasco]

I would recommend you to follow the rules of API 530 and verify the elastic and rupture stresses along the radiant coil. Of course, you are making an important assumption about the fluid pressure on 7th tube.

The best way to check the performance and limits is making a thermomechanical simulation of the entire heater. This way will let you to avoid other kind of problems, not only the high tube skin temperature.

You can access our e-mail for more details in a.velasco@combustia.com

Best regards and look

[Alfredo Velasco]

There are many independent variables to say your fired heater can reach more than 612 C.

I´d recommend you to make a heat balance in your heater and stablish the maximum pressure drop, delta p on transfer lines, etc.

Remember that for this kind of heaters, the design procedure must stablish at least two cases: SOR and EOR. What is your inlet pressure at SOR conditions? What would be the p-inlet at EOR cond?

[Alfredo Velasco]

Other problems like a high increment on the pressure drop, because cavitation of flow control valves. Care with the transfer line.

[Alfredo Velasco]

Important question:

Some of them are:

1. Fuel gas trip, and Velocity Steam
It is known that emergency steam means the steam injected into the radiant box in case of a fire or explosive atmosphere.

2. It is recommended to have one flow control valve per flow pass in coker heaters, just to keep the bulk temperature of all passes to a similar value. It is called “COIL BALANCE”. Of course, flow, pressure and temperature are key variables.

3. Increment the velocity steam if a problem of low flow occurs.

Hope this help

[Alfredo Velasco]

If you are on a conceptual or basic engineering stage, this is one of the main typical questions. As far I know, the time between decoking is one of the key differences in vendor technologies. It is a function of your feedstoke, of course. Can be 3, 4, 7 months.

Operational issues were excellent described by the other member in their answer: TMT, coil pressure drop, coil material metallurgy, etc. AND you operate the heaters: are you operators well trained on combustion?

There are other operational methods to decoke, like pigging, BFW, Steam-air decoking, on-line spalling, etc.

Luck

Alf Velasco

[Author]

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