Reasons for the long replacement time of coal buds with lean gas in fixed-bed batch gas generator furnaces

1. When the furnace is idling during parking, the lean gas meets the requirements in a short time; however, after it is sent to the system for purging, the low pressure of the steam in the system causes the temperature of the gas furnace to rise sharply, which in turn leads to an increase in the amount of combustible gases in the lean gas. Once the steam pressure in the system returns to normal, it is difficult to reduce the temperature of the gas furnace quickly. 2. When coal buds are used as raw material to produce lean gas, the system resistance is high; therefore, the steam pressure must be maintained at a high level. At the same time, the amount of air fed into the furnace must be balanced with the amount of steam fed in, which inevitably results in a higher temperature in the gasification zone of the gas furnace. 3. Excess wind pressure and high furnace temperature, along with too short a residence time of oxygen in the gasification zone, result in the production of large amounts of CO and H2, preventing the combustible gases in the lean gas from decreasing to acceptable levels. 4. The high temperature in the gasification layer results in a higher content of combustible gases in the lean gas. 5. The coal buds are small in size, resulting in high system resistance; this makes it difficult to control the temperature in the gasification zone. Slightly higher temperatures lead to a sharp increase in the content of combustible gases in the lean gas.