Long retractable soot blower operation instructions

2019-06-23

Long retractable soot blower operation instructions

1. Long retractable soot blower operation preparation and procedures

Generally, long retractable soot blower is used for large size boiler with big steam volume, and small size boiler. The furnace volume of big-scale boiler is big enough which makes the portion of soot blowing steam in the total furnace gas small. While for small size boiler, since the portion of blowing medium is large enough to cause the combustible matter accumulated on the dead corner and behind baffle plate to agitate and deflagrate. So care must be taken for small size boilers to prevent deflagration or furnace explosion. Usually there is no such possibility for big size boilers.

Preventive measures must be taken for small size boilers: it should be guaranteed that the boiler’s evaporation is more than 50% of the total volume and the exhauster runs with high flow to avoid deflagration or furnace chamber explosion.

It is recommended that the boiler is cleaned according to the flow direction of furnace gases and soot blowers around the hearth will start in the first place, then super heater and economizer. In case there are very severe deposits to be cleaned, soot blowers at end of boiler flue and at the front should be started up alternately thus preventing serious block at outlet of boiler. If “straightline pass” mode was applied, the dust or deposit from super heater may accumulated around economizer. Above-said suggestions are just for reference, please adjust as per practical operational experience for each boiler.

2. Inspection before start-up

After installation and before start-up of the boiler, it is suggested that the blower be carefully inspected for possible damage from shipment or handling at jobsite. Clean site foreign stuff and wrapping materials. Check the location and mounting of long retractable soot blower correct or not. During dispatch of soot blowers, all oil nipples are filled with lubricating grease, but without lubricant for carriage gear box. Fill enough lubricant into gear box before startup based on operational environment.

CAUTION: The drive pinions on the transmission shaft of the carriage assembly should engage with the gear racks in a good way to avoid abnormal stress on the lance and stuffing box joint to influence the soot blower’s normal work or even cause damage on the equipment.

There is an arrow on the measuring cover plates at both sides of the beam, pointing the corresponding teeth of both gear racks. There is a vertical line pointing the arrow upright. Check the gap between gear shaft central hole and vertical line through the elliptic slot hole of both measuring plates, normally, the gap shall be less than 3mm.

CAUTION: Cut off the power supply before adjusting the wrong engagement of carriage gears.

In case wrong gear teeth engagement was found, be sure re-install carriage assembly. What only needs to be done is removing the movable guide angle bar at one side of beam and adjust the engaged teeth between gear and gear rack to fix the problem.

3. Test run

Cut off power supply before start-up. Rotate the square tang on the carriage assembly with ratchet wheel spanner or special electric (pneumatic) spanner or hand wheel to make it advance until the carriage assembly is released from the rear limit switch. Check the front and rear limit switches for freedom of operation, and ensure the poking pin of carriage assy. can be reliably hit the poking fork of limit switch. In case the soot blowers use spiral line phase change mechanism, manually operate carriage and make it move forward 10-15cm, then go back to rear end, thus the gear of carriage could turn one more tooth.

CAUTION: All the electric wires on spot should be meggered to the ground and each wire should be marked for trace from the electrical control panel to the wiring terminals.

Connect the power supply, check the rotation direction of electric motor. Now long retractable soot blower is ready for being put in operation. Press start button and let it move forward for some distance, stir the front limit switch by hand, making the lance tube retract.

CAUTION: the front limit switch poking fork must be stirred back to proper position, so that next time when soot blower travels forward, the carriage poking pin could hit.

After long retractable soot blower is started up, check the forward or backward travels of soot blowers for any obstruction. Ensure the lance tube is supported by the front support rollers in normal way. After the test run, allow the electrical control panel to control the operation, perform final check
for continuous operation.

After several runs of soot blower, check the gaskets for any loose between poppet valve and companion flange, feed tube and poppet valve, lance tube and flange. When in hot run, adjust the packing gland assembly and packing set for valve stem and feed tube to an appropriate tightness.

CAUTION: Do not overtighten the packing glands of valve stem and feed tube. It is enough to tighten them to an extent that no leakage takes place. A too tight packing gland of valve stem will decrease the life span of packing set, and also influence the reposition of valve stem. For feed tube, it will increase the load of soot blower and may even damage feed tube. Consequently, it is common that a little of steam and condensate water appear at both packing glands when the poppet valve opens.

4. Blowing pressure adjustment

A pressure adjusting disc is installed at side of poppet valve outlet which enable an adjustment of blowing media as required. When assembling at workshop, the disc was opened for about one turn. The pressure adjusting disc has to be adjusted to obtain a proper pressure according to the parameter provided by the company.

There is a pressure adjusting disc inside valve to adjust the output pressure. When adjusting the pressure of blowing, please remove the lock nut. Turn the disc to increase the opening in order to get a higher pressure. Or turn the disc to decrease the opening and get a lower pressure. Use a screws driver or similar tools to turn the pressure adjusting disc. Refer to Figure 1 for reference.

Protection measures must be taken when adjusting high temperature steam to avoid damaging pressure gauge. Connect the pressure gauge and poppet valve with a annular pipe and fill up the pipe with water. Using screw union to connect the pipe and pressure gauge and make sure no water leaking. The installation position of pressure gauge is indicated in Figure 1.

CAUTION: DO NOT ADJUST PRESSURE WHEN THE POPPET VALVE IS OPEN.

poppet valve

When boiler is put in operation in the first time, the water-cooled pipes have character of resisting fly ash or slag. Therefore, at early stage of boiler operation, it seems that the soot blowing pressure is higher than required, and this phenomenon may last a couple of weeks. During this period, it is not necessary to have soot blowers work very often. Afterwards, when a layer of dust or slag accumulate on pipes, and it is a little bit difficult to clean the slag or dust, then the recommended blowing pressure is basically suitable.

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