The process of heating a substance under isolated air conditions is called dry distillation. During the dry distillation process, the composition and aggregation state of the raw material will change, and the product contains solid, gaseous, and liquid substances. Dry distillation of wood can yield charcoal, wood tar, and wood gas, etc; For coal dry distillation, coke, coal tar, crude ammonia water, crude benzene, and coke oven gas can be obtained; For some combustible household waste, dry distillation can also be carried out, which processes household waste and produces by-products such as gas and other substances.