Generally, the water washing tank is used in conjunction with a water ejector, the sample gas mixed with steam passes through the sampling tube and is ejected by water at the water ejector connected to the sample gas inlet pipe of the water washing tank. After that, the sample gas mixes with the cooling water, enters the lower part of the inner sleeve of the water washing tank through the sample gas inlet pipe(The water washing tank is filled with cooling water). The sample gas mixed with steam is fully contacted with water in the inner sleeve, removes impurities such as dust and tar from the sample gas. The steam is then cooled and condensed. The washed sample gas gathers above the cooling water level in the water washing tank and enters the gas-liquid separator(optional or alternative) through the sample gas outlet pipe for gas-liquid separation. The sample gas is discharged through the exhaust port at the top of the gas-liquid separator for further processing, while the condensate returns to the space between the inner and outer tanks of the water washing tank through the condensate return pipe located below the gas-liquid separator. The washing water in the water washing tank is drained out of the cabinet through the drain port(pressure-free discharge). The drainage pipe outside the water washing tank forms a water seal, maintaining a certain pressure inside the tank and preventing any sample gas from being discharged at the drainage outlet. The dust and other impurities accumulated in the water washing tank can be discharged and cleaned by opening the end cap at the bottom of the tank.