Hybrid furnace with fuel and/or electricity

A process for retrofitting a fuel-fired heater, having a radiant heating section, one or more process coils in the radiant heating section, and a flue gas stack, for heating petroleum, petrochemical, chemical process fluids, and boiler feed water or steam generation to include a combination of electrical heating elements and fuel-fired burners, the process comprising:

• removing one or more fuel-fired burners disposed at a lower elevation in the radiant heating section;
• retaining one or more fuel-fired burners disposed at an upper elevation in the radiant heating section;
• disposing one or more layers of refractory material in the lower elevation in the radiant heating section;
• disposing one or more electrical heating elements in the lower elevation in the radiant heating section proximate a surface of the one or more layers of refractory material, wherein the one or more electrical heating elements are disposed at a distance of 12 to 18 inches from the one or more process coils;
• and
• disposing an internal baffle between the upper elevation and the lower elevation, the internal baffle configured to provide shielding of the one or more electrical heating elements from flame and combustion gases from the one or more fuel-fired burners.

A method of retrofitting a cracking heater comprising a radiant heating zone and a convective heating zone, wherein the radiant heating zone comprises a floor, floor burners disposed in the floor, a refractory wall including a first wall opposite a second wall, wall burners disposed along a height of the first wall and the second wall, and a radiant coil disposed within the radiant heating zone intermediate the first wall and the second wall, the method comprising:

• installing an intermediate floor at an elevation below a wall burner;
• installing a second refractory wall from the floor to the intermediate floor;
• moving a floor burner from the floor to the intermediate floor;
• installing one or more electrical heating elements along a height of the second refractory wall.