TWMS18L is suitable for the rice mill with 50tons per day. TWMS25L is suitable for the rice mill with 70-90tons per day. TWMS30L is suitable for the rice mill with 100-120 tons per day. TWMS16L is iron roll whitener, suitable for the rice mill with 100-120 tons per day. The multiple aie inlets for air entering into the whitening chamber, the new enhanced air-jetting technique and the air volume passing through the whitening chamber which is 2.28 times higher than normal type, the new mechanical structures such as the receiving bin for cooling rice grains and the double adjustable counter pressure valves for air locking can increase the negative pressure inside the machine, hence realizing low temperature rice whitening under negative pressure.