The moisture content of coke in the open-air storage yard in rainy days can reach about 13~ 15%, which is 7~9% higher than the normal moisture content of 6%. Therefore, 70~90 kilograms of coke should be added to the furnace per ton, which is an empirical figure. In order to accurately add moisture coke, it is necessary to analyze and measure the water content of coke after rain and calculate the increased water content per ton of coke compared with normal period.