I didn't imagine I would find a fire for boiling made with a base of rin, I thought that was natural in Latin America, but in Spain... In Canada we use specific devices in the city, in the countryside, the areas around the city, they are usually made of bricks or stones and on the side they have a kind of fan that serves to fan the flame without effort and fan the flame. Some more specialised ones even have a chimney.
My parents don't live in Spain, but anyway, sometimes they prepare some dishes over the open fire in this way, the place is in the back yard under a little roof, made especially for these events of cooking outside (once or twice per month)