【正文】 . 6. Punch out the two inner spring pins securing the dome to the shafts. 7. Withdraw the shafts and lift out the dome . Note if there are any shims present on the shafts. The shims are occasionally fitted at the factory for centralising the dome and should therefore be refitted on subsequent overhauls. 8. The bearings and seals can now be removed by driving them towards the centre of the valve. 9. All machined surfaces should now be thoroughly cleaned/degreased and inspected. 10. Check for surface irregularities in the dome and shafts and replace if necessary. Also deburr the edges of the two holes and the leading edge of each drive shaft to prevent damage to the replacement seals/bearings on reassembly. 11. Carefully fit the replacement seal into the locating r。Removal/Replacement of DomeValve Bearings39。6： Abnormal ash falling 1 If the ash quantity than the normal condition, the conveying pressure is much lower than the normal conveying pressur Knock the ash hopper vibrator and rigid joints Adjust aeration gas quantity Check the ventpipe condition and eliminate faultIncreasing exhausting with the vent valve, accelerate ash falling1. Improper orifice plate setting，too fast material flowing Adjust the orifice plate gas quantity2. Low conveying load Check the vessel filling time, vent valve and vibrator setting, increase the falling ash quantity in the pump7： bad abrasion of pipe /bend 3. Improper pipe bend installation Locate the position1 The gas source pressure is lower than the design requirement Check the air receiver local gas source pressure.2 Feedback gas pipeline is obstructed.Check pressure gauge display of the local pneumatic panel.When the pressure is lower than the feedback pressure, transact as the following 3,4,5 items.。 the smaller gas dosage is, the lighter quiver is. If there being no the sound and vibration, it is possible that blockage occurs in the plate and isolated valve caused by impurity. It is necessary to clear the orifice plate and isolated valve and blow the pipe. 5. Conveying AirAvoid more water content in the conveying air. In the dry day, make drainage in air receiver once 2hours, in the wet day, increase the drainage times. 2.. Fault Diagnosis And Managing Methods Of Ash Conveying System Warning: Prior to system fault diagnosis, check air amp。 and when boiler being in high load operation, shorten the circle interval time to meet the requirement of the great quantity conveying. 4) Ash conveying system operation method when boiler being shutdown：After the boiler and ESP halts, the ESP rapping system should keep operating more than 3 hours. Then the ash temperature starts to fall, it’s necessary to decrease the pump ash containing and keep the ash conveying system running continuously, until ensure that the hopper is cleaned up, then open the ESP manhole for checking.a) System operation to remove blockageIt is necessary to remove blockage when pipe blockage occurs in the conveying as follows:Blockage removing method：A: Stop “run”, start “blow” on the CRT operation menu. When the pipe pressure is high, shut off the air manual valve on the pipeline, open the manual blockage relief valve，discharge ash into the ash hopper by the blockage relief pipe. And carry on “pressured—shut off the air valve after pressure increasing—open the blockage relief valve —shut off the blockage relief valve after pressure starting to fall”，stop the operation until the highest pressure reaches the blowing pressure, then purging system twice finally.B: If the blockage can not be handled with method A, open the manual vent valve of master pump (or other pumps) at higher pressure, with this method, take out the ash from the pipe to the pump.Need to closely observe the conveying system condition during the ash conveying. The regular system walkdown will be required while keep monitoring the CRT.Spot walkdown Content：1. Review the temperature on the adaptors above inlet dome valve of vessels.Normally, for the first field , the joint temperature is 90—100℃，for the second field temperature , that is 50—70℃，and for the third to the fifth field ,that is 30—50℃.Review the temperature of this point to check the status of ash falling and ash accumulating in ash hopper. If the joints temperature in the same field has great difference, it is possible that the ash falling will be uneven or bad ash falling occurs in some hoppers. It is necessary to adjust the load distribution of the flue and ESP, adjust hopper aeration gas quantity and ash feeding time, adjust the circle interval time, make the ash falling normal and ensure good operation circle. Review all the joint temperature after a period (about a week) of each operation starting.2. Ash Falling During the period of the “falling –conveying –conveying over”, know the ash falling and conveying status by knocking the pump body, or check the ash thickness by opening the manual vent valve. This job must be carried out to know the basic ash conveying status especially at the beginning of the conveying and the pump being still not full. 3. VentPipe And Blockage Relief Pipe StatusSetting ventpipe and valves in the MD pump, the vent valve is opened to exhaust when the MD pump inlet dome valve is opened for ash falling by gravity. At the normal condition, it takes 10～20 seconds to full the pump, and the ash falling pipe temperature increases and ventpipe works normally. If there is enough ash in the ESP hopper, but it is still hard to fill the pump, maybe the ventpipe acts abnormally without enough venting. Here, the following methods can be used: A：Knock the ventpipe before opening the vent valve。 Maintenance2. Fault Diagnosis And Managing Methods3. Dome Valve Maintenance Instructions