SOP for Traveling Grate Boiler

Boiler Start-up can be termed as cold start-up when there is no pressure or when pressure is less than 2-bar (g) in the steam drum.

In a cold start up, possibilities of some inspection or maintenance works having been done is presumed. A walk down check is required and the boiler and its auxiliaries are to be prepared meticulously for a start-up. Before a walk down check ensure that all work permits have been returned, safety tags are removed and permission from maintenance boiler start up is available.

Cold start up

Ensure DM water storage tank level normal and healthy condition of WTP for adequate water.
Ensure availability of fuel quantity and power supply with DG backup.
Ensure trial runs (healthiness) of all equipment including fuel handling, ash handling / auxiliaries, motorized valves, actuators, control valves and PRDS controls are completed successfully.
Ensure that all interlocks / protection and controls are checked & taken in line.
Ensure expansion points are cleaned & tramps are in good condition.
Ensure Boiler manholes and flue gas path system manholes are boxed up.
Ensure availability of chemical dosing system and readiness of drum level gauge glass with illuminator assembly.
Ensure availability of cooling water, instrument air and service air.
Start the ACW pump, Instrument Air & Service Air Compressor.
Ensure all rotary air lock valves of modular bank hopper and economizer hopper gates are opened and then start RAVs.
Ensure healthiness of all dampers and keep them in open/close marked positions as and when required.
Open all air releases/vent valves in boiler drum and open super heater header drains and its vent valves.
Ensure all boiler bottom ring header drains, blow down valves and main steam stop valves including its bypass valves are closed.
Ensure Deaerator level normal. If level is low, make it normal through control valve by DM transfer pump.
Ensure BFP oil level of bearings normal, minimum recirculation, balancing leak off valves & suction valves open, cooling water pressure normal.
Ensure sufficient suction pressure & suction differential pressure across strainer is normal.
Start BFP from control room. Ensure suction pressure, balancing pressure & discharge pressure normal. Bearing temperature & Vibrations normal. Ensure motor draws current normal & sound normal. Shut the BFP immediately if any abnormal condition and check thoroughly before restart.
Start water filling the boiler drum through 30 % control valve and maintain the drum level up to 30%.
Start the Ash handling plant prior to light up the Boiler. Then start all hoppers RAV.
Charge the hopper heaters, Insulator heaters of ESP prior to Boiler light up.
Start the purge air blower, collecting & emitting rapping motors prior to boiler light up.
Stack fire wood / baled bagasse inside the furnace for light up, put the fire and maintain the moderate temperature of furnace without fan by keeping suction damper & discharge damper of ID fan open.
Spread the fire throughout the furnace.
Raise the furnace temperature up to 150 °C to 250 °C.
After ensure the furnace temperature of 250 deg C, start ID, FD & SA. And maintain the furnace draft -2 to -10 mmwc, FD air discharge pressure by maintaining the rpm in the range of 10 to 15 %, SA air discharge pressure by maintaining the rpm in the range of 40 to 45 % with feedback of field supervisor.
Start screw feeder and then drum feeder including fuel feeding system (Fuel Handling System) and slowly rise the furnace temp by feeding fuel (maintaining the rpm of drum feeder feedback of field supervisor).
Maintain the steam drum level and if exceeds, maintain the level by giving IBD.
When drum pressure rises to 2 to 2.5 kg/cm2, close the drum air vents.
When drum pressure raises 5 kg/cm2, close all super heater vents, drains except secondary super heater outlet header vent & drain valves in crack opened condition. Open start up vent valve (5%) initially and increase the start up vent valve opening gradually according to steam pressure & temperature as per start up curve to allow the steam flow through SH.
At drum pressure of 5 kg/cm2, quickly give the blow down through IBD and furnace bottom ring header for 3 minutes.
Start HP & LP dosing and maintain recommended drum water parameters of boiler. Keep the CBD at minimum opening to maintain recommended residual PO4 & conductivity of drum water.
Check & record thermal expansion of boiler pressure parts and record the bearings temperature & vibrations of auxiliary equipment’s associated with Boiler.
Start & Stop the traveling grate as per requirement during light up and Ensure sub merge belt conveyor for bottom ash disposal is in running condition.
Follow the cold start up curve and raise the pressure & temperature of Boiler as per the curve. Start another ID, FD & SA fan and BFP as per requirement.
When boiler raises above pressure of 50 to 55% of design and temperature above 300 to 350deg c, charge the main steam line. Before charging the main steam line, open all the drains at 100 % and warm up vents at minimum opening and then open the MSSV bypass valve.
After ensured all condensate removed & colorless steam comes through drains, keep all the drains in crack position, then open main steam stop valve and close the bypass steam valve.
If available Charge the PRDS of pegging steam and charge the Deaerator. Maintain the PRDS pressure and temperature as per Deaerator design.
After getting the start permissive of ESP, charge the ESP.
Observe Ash Conveyor or seal air pressure, conveying air vessel pressure of AHP is normal.

Boiler Warm Start Up

Start the Power supply or DG set.
Keep the boiler in hot box up.
Maintain the drum level accordingly.
After this give clearance to start the boiler.
Start the ash handling system accordingly
Ensure the de-aerator level.
Start ACW & compressor.
Start & regulate ID, FD & SA fans as per furnace draft.
Start fuel handling system.
Open start-up vent.
Start boiler feed pump.
Take fuel to boiler & Raise the pressure and temperature gradually warm start-up curve.
After reaching the pressure 25 kg/cm2 give blow down through ring headers.
After reaching the pressure 30 to 35% of design and temperature above 300 to 350deg c, open MSSV by pass valve and warm up the line up to TSSV.
Give clearance for Next Process.
Slowly raise the pressure and temperature as per design.

Boiler Hot Start Up

Check the availability of import power Supply or DG set and Start.
Check the reason for tripping and after the analysis give the clearance to start the boiler.
Close the MSSV and keep boiler in hot box up.
Start the ACW and compressor.
Start the boilers feed pumps and maintain the drum level.
Start the ash handling system.
Observe seal air pressure, conveying air vessel pressure of AHP is normal.
Start ID, FD, SA fans as per the requirements.
Start the fuel feeding system and monitor the combustion feedback continuously.
After reaching the pressure 30 to 35% of design and temperature above 300 to 350deg c, open MSSV by pass valve and warm up the line up to TSSV.
Open the MSSV main valve.
Raise the pressure and temperature up to as per design.
Give the clearance for rolling of the turbine or next process.