Abstract: The present invention relates to a catalytic cracking process and a device used in the process in particular, the present invention provides a catalytic cracking process, which comprises which comprises: 1) catalytic cracking a feedstock in the first riser for less than about 1.5 second and sending the resultant stream into the first separating device,; 2) catalytic cracking the recycle oil obtained from the first separating device in the second riser for less than about 1.

Abstract: A boring bit for drilling is provided comprising one set of rotatable toothed wheels secured thereon as well as one set of tubular nozzles and one central nozzle for injecting drilling fluid from a chamber in bit body toward the bottom of a borehole. The boring bit comprises the inlet end of said tubular nozzle being secured on the bit body and connected with said chamber while its outlet end is quite close during operation to the lowest point of toothed wheels and the bottom of a borehole, and the fluid passage of said tubular nozzle from the inlet end to the outlet end is straight and cylindrical. Branch fluid passages are provided on the main fluid passage of said central nozzle for washing and cooling toothed wheels.