Ava Zim, according to http://www.biocharretort.com/ it takes 4 hours to 8 hours, from lighting to shutdown. Then more time to wait for things to cool down, at least overnight. I usually load my barrel retort slowly during several days (I’m retired.), and cover it with a big tub. Then, I check the hourly weather forecast for wind direction and wind speed and humidity. Usually, I ignite at sunrise, or shortly before, when the grass if any) is coated with dew. A load of small branches is turned to a glowing bed of charcoal in 1.5 hours. If I use larger logs in the 3" to 4" diameter, it will need to burn for an additional hour (total = 2.5 hours). Then, I can cover the barrel and wait until the next day, or I can simply dump 20 gallons of rainwater into the charcoal. Since the holes around the bottom edge of the barrel are covered with clay, the water stays in the barrel and puts out the fire completely. When I first ignite the load, I add lots of small thorny brush such as mesquite and huisache (sweet acacia) to insure a good load of char on the very top, which is what burns any smoke rising from the larger wood inside the barrel. (My two barrel system has one barrel on top which acts as a big chimney. I throw paper balls and acacia into that top barrel to really get things going.)
I would keep the hinges on the side, otherwise it might bump your knees when you are trying to load the wood into the retort.