Maintenance Procedure of Major Components of Steam Power Plant Boiler
The boiler safety devices are designed to prevent dangerous conditions from turning into disasters, only proper belles interne perves the development dangerous operating conditions in the first place The only w the plant manager can be confident that control of safety devices are fustioning property is by regularly performing requires maintenance, testing and inspection.
General procedure boiler safety and maintance:
Its important that egalarty observe and check on the status of a variety of boiler components Some basic and general steps include:
1. Check for proper functioning of controls, including the pressure gauge. low water utot devices thermometers temperature controls, gange elass and pressure relief valve.
2. Check drains and blow offs to ensure they're functional.
3. Check the fuel system for leaks and ensure that fuel filters and strainers are replaced regularly
4. Check and Ensure that shut-off valves are leak-tight. If unsure, perform a leak tightness test
5. Ensure that the valves in instrument lines are functioning properly
6. Open the boiler vent valve or top tri-cock to vent air and fill the boiler with treated water to its proper level. Check that the expansion tank is properly filled.
7. Check and verify that vent valve on gas-fired boilers is operating as required and that the vent isn't clogged
8. Check and verify that the flame scanner or sensors are properly connected and functioning
9. Check all the instruments and safety devices for proper setting. Ensure that the water pressure regulator functions as required.
10. Ensure the recirculation pump works as required.
11. Confirm that there are no signs of overheating, commotion or erosion.
12. Check thuat heating system isolation valves are functioning properly.
13. Verify that there are no leaks from any part of the boiler or external piping Repair cracked surfaces immediately, bugs or other deformities indicate defective control for safety devices, or improper burner operation.
14. Test safety valves on a regular schedule Replace Leaking safety valves
15. Inspect owner fuel cu ce and operation. Verify that it shuts off the fac supply to the boiler as required.
Boiler Drum Inspection and Maintenance :
Observe the drumby physical orientation for referencing observations made during the inspection. The drum is divided into five sections.drum head at entrance both end of shell. cylindrical shell and drum bead at exit check the seal and gasket of each part if damage then replace it. Interior components such as steam separators piping, asd chevron scrubbers, should be referenced by sequential numbers starting at the drum's entrance and continuing toward the drum's exit. Check each penetration, bore holes or pipe sleeves for any cracks at the edges of openings cracks in the attachment welds and any porosity. These openings should be free of debris, cracks, gouges, and appreciable loss of material thickness in the head and the attached piping Clean boiler heat transfer surfaces to remove the soot build up that acts like an insulator and diminishes the efficiency of heat transfer between combustion gas and steam generation. Non-destructive examination of wall and head welds using phase array or RT, wet fluorescent magnetic particle (wet mag) for nozzles. drum door, bore holes, tube sheet, and attachment welds.
During the inspection if any problem occurs then it replace it or repair it for proper functioning of boiler drum
The water gauge glass on a boiler enables the operator to observe and verify visually the actual water level in the boiler. If not properly cleaned and maintained, the sight glass might show there is suficient water when the boiler is actually operating in a low water condition A stain or coating sometimes develops on the inside of the glass where it's in contact with boiling water, and this stain can give the nte water in the brider, especially when appearance of adequate water in the boiler, espial e the the glass is either completely full or empty of water
If necessary, replace the glass even if the boiler must be shut down to do so. It's also crucial to perform periodic maintenance of the piping leading to the glass gauge. The Piping can become clogged and should be cleaned and inspected regularly to avoid false water level nt
The fuel system, particularly the bumer requires periodic cleaning and routine maintenance. Failure Failure to maintain the fuel system in good working order could result in excessive fuel costs. loss of heat transfer or even a boler explosion.
Optimal air-to-fuel ratio Analyzing the the gas allows you to measure the amount of oxygen and the stack temperature to calculate efficiency. Adjustments can es be made to optimize the excess air and incoming air amperatures.
Maintenance Procedures Economizer:
1. Cleaning by Soot Blowing Carry out regular operation of the sot blowing device, Le, tue ader every watch etc.
2. Draft loss in the exhaust gas side has increased while e plant is in operation, the soot blowing frequency must be increased until a suitable water washing procedure has conducted.
3. When the draft loss is more than two times of the reference guide and the plant is affected.
Water Washing procedures:
a. When carrying out water washing, it is better to start when the economizer is still warm as it has greater soot removing effect.
b. Open the soot drain valve of the economizer dust catcher and make sure that it is not clogged including the piping.
c. Close all the manholes except on the top cover manhole to make the economizer soot washing effective. When there are other doors open, the washing water might not fall at the bottom due to the effect of ventilation.
d. Prepare sufficient amount of fresh water, and keep the supply pressure above 0.2 MPa or as per the maker's instruction book.
e) Spray fresh water at each side of the tubes and from top to bottom. The soot that is washed from the top maybe caught in the lower tubes. Operate the boiler circulating pump momentarily to force dry the soot so that it can be effectively removed. Damped soot will be dried by the boiler water circulating which stimulates shrinkage; the soot is isolated from the heating surface and is easily released.
f. There are cases that the soot from the dust catcher cannot be washed away effectively or clogging ) might occur in the drain piping. Neutralize the soot by using sodium hydroxide (NaOH). As a guide, h 10 kg of sodium hydroxide (NAOH) shall be put in every I m of the drainage in the drainage tank Ta proven the drainage pipe from clogging and comedian, carefully wash the drain pipe and the drainage tank with fresh water.
Air preheater:
Since the flue gas is howed in the pipe longitudinal wall, so the heat transfer is poor. In order to enhance heat transfer and prevent dust use intable high flue gas flow rate. The air is in the tube for lateral erosion, heat transfer is better, but the flow resistance in large, so should adopt the bottom of the air flow rate (below the smoke speed). To enhance the overall heat transfer effect, the air and flue gas flow rate and the ratio between the two should be kept in the appropriate range.
1) In order to eliminate the air preheater air leakage, in the boiler after the shutdown of a serious air leakage test the air preheater leak detection and timely elimination of leakage points. Maintenance of the air preheater where the expansion point to check, so that the air preheater in the run without expansion blocked, resulting in leakage of steel pipe leakage phenomenon.
2) Blower or a fan into the air preheater before the installation of the air duct system, as far as possible to improve the air preheater inlet temperature above 20"C.
3) Air preheater inlet flue gas temperature shall not be lower than 350°C
4) The data in the boiler load changes can be adjusted according to the corresponding level of smoke; to strengthen the inspection found that the fan, a fan air duct vibration, timely operation adjustment, reasonable to avoid, blower, a fan surge point.
5) Boiler blower has been used to adjust the liquid even, the fan inlet and outlet haftle fully open, with the fan speed to adjust the boiler air volume, air duct surge phenomenon has been avoided.
6) To avoid fouling long stay in the flue strengthen the tail flue parts of the soot work
7) Normal operation of the boiler, to ensure a proper high furnace negative pressure to improve the tail fouling.
8) To reduce the amount of sulphur trioxide production, a reasonable down side excess air coefficient. As long as there is excessive oxygen in the flue gas, sulphur dioxide can continue to be converted into sulphur trioside, excessive oxygen and the amount of sulphur dioxide in the amount of sulphur increased, the flue gas dew point temperature can be increased to 130°C to 150°C
In short, the air preheater is the bottom component of the boiler unit in the metal temperature of the bottom of the heating surface, but also the boiler along the flue gas process of the last heating surface. The air preheater is an important part of a modern boiler.
Steam Turbine Maintenance Parameter :
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion Deposits cause output and efficiency to drop, by reducing the efficiency of energy transfer and eventually restricting steam flow. Performance analysis can be applied to most machines, rotating and stationary. It is the one condition monitoring technique which allows the optimum time for restorative maintenance to be calculated, where the deterioration results in increased fuel consumption, or in reduced output, or both.
1. Steam turbine inlet and exhaust pressure and temperature, speed and load.
2. Steam turbine rotor and shell differential expansion
3. Water and steam purity at the main steam inlet and the condensate pump discharge.
4. Extraction line of thermocouple to detect water inlet.
5. Lube oil and hydraulic fluid supply pressure and temperature
6. Cooling water supplying pressure and temperature for lube oil and hydraulic fluid system.
7. Journal bearing and thrust bearing metal temperature fore turbine and gear box.
The following problem are found so check it, repair or replace it
a) Blading : Erosion by solid particles also erosion by water droplets on latter LP blades, Parts breaking off
b) Bearings : Scoring damage to white metal
c) Rotors : Rubbing, temporary unbalance, cracking, misalignment"
d) Valve spindles shaft inner stage glands (seals) casing joints LP manhole gaskets Internal steam piping and fittings Effect of seal water is relatively greater for blading For impulse machines, the relative lost output for each 25m increase above design clearance of about 600 m.
e) Steam valve strainers, valves, spindles : Likely to occur gradually, mostly in areas around 260C. Some on load blade washing occurs with forced steam cooling Performance analysis detects. Blade surface roughness has biggest effect at higher steam pressures.
f) Condenser : Air in leakage Tube fouling
g) Feed water heaters : Air in leakage, tube fouling by scale or oil
