A flame broiler is a commercial mechanical gas grill used to cook various products. It is in use by the Burger King fast-food restaurant chain and was also used by the Burger Chef chain.
The device consists of a ladder-type conveyor chain that transports a hamburger patty over gas broiler tubes that provides a gas flame. The underside of the meat patty directly contacts the flames as the meat is conveyed through the broiler enclosure. The top part of meat patty is cooked by latent heat provided by fire bricks that are also heated by the gas flame.
References
Flame broiler Wikipedia(Text) CC BY-SA