Problem of influence of stream chopper (pulsator) for character of coal-dust mixture movement in a tube was considered. It was shown that this influence is determined by the x parameter which depends on the tube diameter, fluid viscosity and interruption frequency. When x>>1 expense pulsations is shifted by phase on half-cycle in regard to pressure pulsations. At the same time the influence of pulsator weakens at major frequencies. Narrow enough range exists in which pulsator influence for a stream is maximal and conditions of coal-dust torch ignition is optimal.