DRYING METHOD OF MOULDED AIR BRICK Russian patent published in 2015 - IPC C04B33/30 F26B3/02 

FIELD: construction.

SUBSTANCE: during the drying operation, to one of the end faces of the arbitrary chosen brick of a batch of bricks arranged in a drier there supplied is a pulse ultrasound source, and to the opposite end face of the same brick there connected is an ultrasound receiver; ultrasonic pulse oscillations are excited in the ultrasound source and time intervals τ of passage by each ultrasound pulse of the distance from one end face of the above brick to the other end face of the same brick are constantly determined. Rate of change of the above intervals $$\frac{d\tau }{dt}$$ is determined during the drying time by differentiation of duration of τ intervals as to time t. Before the first minimum of change rate of intervals as to time $$\frac{d\tau }{dt}=\min 1$$ is achieved, temperature of the heat carrier is linearly increased at the rate of 30-35 deg/h. After the first minimum of change rate of intervals as to time $$\frac{d\tau }{dt}=\min 1$$ is achieved before maximum value of interval τ=max is achieved, heat carrier temperature rise rate is changed again and set within the range of 5-6 deg/h. After the second minimum of change rate of intervals as to time $$\frac{d\tau }{dt}=\min 2$$ is achieved, heat carrier temperature is linearly changed again and set within the range of 8-10 deg/h. After expiry of 2.5-3 h of temperature rise, heat carrier temperature is stabilised at the achieved level; with that, during the brick drying process, continuous measurement of moisture content in a brick is made and the above stabilised temperature value is maintained till the specified final moisture content is achieved; after that, drying is stopped.

EFFECT: reduction of drying time; absence of cracks and increase of average density and compressive strength of brick that passed drying as per the proposed method.

4 dwg, 1 tbl