Summary for long retractable soot blower
The long retractable soot blower (Refer to Figure 1) is mainly used to clean the soot and slag accumulated on the heating surfaces of boilers by steam or compressed air, especially for the superheaters, re-heaters and economizers. Its travel distance is designed as required. It is also used for cleaning the accumulative soot located on the top of furnace and air preheater tubes.
A. Soot blowing principle
The basic working principle of long retractable soot blower is that compressed air or steam is ejected out continuously through the nozzles (one, two nozzles generally) at the front end of the retractable rotary lance tube and clean the accumulative dusts and deposits on the heating surface. The nozzle’s moving track is a spiral line whose helical pitch is determined by the soot blower’s travel distance and blowing requirements (basic helical pitch of HXC-5: 100, 150 or 200mm). When retracting, soot blowers nozzle’s moving track has 1/2 pitch stagger with forward moving track. (Figure 2 shows the blowing track, two-nozzle and 100mm travel distance).
B. Main components
⑴ High efficient nozzle – specially selected for each soot blower
⑵ Nozzle moving mechanism – Lance tube, Carriage Assembly and Motor.
⑶ Steam supply parts to nozzles – Poppet valve, Feed tube, Packing gland and Lance tube.
⑷ Supporting and covering Element – Beam Assembly with supporting and plugs.
⑸ Control system – protected by beam assembly, supplying control power and motor power, controlling the operation of soot blower.
C. Soot blowing process
Soot blowing cycle begins with the lance tube staying at the original place (refer to Figure 1). When the soot blower is powered, the carriage runs forward along the guide rails on both sides of the boxlike beam driven by the motor. The lance tube rotates and enters the furnace to the preset position, and the trigger pin on the carriage triggers the Valve Turn-on Assembly to open the valve and soot blowing starts. The carriage runs forward continuously to the front end position (the end point of travel) to trips the front limit switch to reverse rotation of the motor. The carriage then moves backward with the lance tube along a different track from the forward’s until it reach some point close to furnace wall and poppet valve shuts off and soot blowing stops. The carriage continues to retract to the start point to trips the rear limit switch to stop the motor. Now a cycle of soot blowing is completed.