Boiler Maintenance
KETEL STEAM (BOILER)
Boilers (steam generators) function to convert water into steam. The very high pressure steam produced by the boiler is used to rotate the turbine.
The water supplied to the boiler, first entered the economizer inlet header, was continuously distributed to the economizer elements, reunited in the eco outlet header and then distributed to the steam drum. The economizer is located inside the backpass area (on the back of the boiler house), while the steam drum is on the front of the roof area, called the economizer because this section serves to increase the temperature of the water that just entered the boiler by utilizing the exhaust gas from burning coal in the furnace area (combustion chamber). By preheating the economizer the steam boiler efficiency can be increased, due to heating by convection in the furnace area and because of the gravitational force, the water in the steam drum water experiences downward circulation to the water wall lower header through pipe downcomers. From the waterwall the lower header of the water returns to circulation due to heat, rises to the water wall upper header via a tube-tube water wall panel. Then from the waterwall upper header the water is returned to the steam drum through the riser pipes.
So due to the burning of coal heat water experiences continuous circulation. This circulation causes the water in the water wall panel & steam drum to partially turn into steam.
Kwala Honey Sugar Factory (PGKM) for steam processing and electricity generation needs, using Yoshimine Boiler Brand Type h-1600 S , fuel needs around 4 tons / hour by utilizing bagasse as fuel, steam production of 20 tons of steam / hour and working pressure 21 kg / cm 2 .
The steam boiler used by the Kwala Honey Sugar Factory (PGKM) is a water pipe boiler, the boiler resistance depends on the water quality of the boiler. The temperature of the water vapor from the kettle is 222 o C, the temperature of the feed water is 105 o C, and the air temperature is 30 o C. The steam boiler is heated by burning bagasse provided the previous day. The fuel used is dried bagasse.
To find out the ratio of fuel with the weight of water that evaporates in 1 hour can be calculated based on the formula below:
Where, we = the weight of water that evaporates
Ws = the amount of steam produced [kg] = 20 tons = 20,000 kg
Wf = weight of fuel [kg] = 4 tons = 4000 kg
Then, 20000 kg
From the results of calculations, it is known that the ratio of fuel to the weight of evaporating water is 1: 5. The steam obtained is used as a turbine to produce electricity and the rest is used to assist the production process.
Tool specification data:
Amount: 2 units
Brand: Yoshimine Boiler
Type: h-1600 S
Maximum vapor pressure: 24 kg / cm 2
Working pressure: 20 kg / cm 2
Steam temperature: 325 0 C
Kettle type: Water pipe kettle
Number of pipes: 1339 pieces
3.1.1 Main boiler equipment
In the boiler there are actually two parts of construction that have their respective functions, namely the part that serves to generate heat from the fuel combustion process by utilizing the heat that can evaporate the water.
- Combustion chamber
The combustion chamber is divided into 2 (two) rooms, namely:
The first room : functions as a combustion chamber, some of the heat produced is received directly by the water pipes inside the kitchen space, namely the water pipes from the top drum to the front and back headers and the water pipes from the top drum to the side header left right.
The second room : is the hot gas space received from the combustion results in the first space. In this second chamber most of the heat from the gas is received by the water pipes from the top drum to the lower drum.
In the first combustion chamber, combustion air is blown by a foerced draft fan through small holes around the walls of the combustion chamber and through the fire grates.
The amount of air needed is arranged through the fire grates, which are controlled from the boiler switch panel. Whereas in the second room, the hot gas is sucked by an induced draft fan, so that heat flows from the first chamber to the second room of the combustion kitchen.
- Top drum
The top drum serves as a place of steam formation which is equipped with barriers holding water grains to minimize the possibility of water being carried away by steam.
Figure 2. Upper drum
- Bottom drum
The bottom drum functions as a heating place for kettle water in which plates are collected collecting fine deposits to facilitate blow down.
Figure 3. Bottom drum
- Advanced steam pipe (superheater piper)
The wet vapors resulting from evaporation in the upper drum have a temperature of 206-217 0 C, before they can be used for steam turbines . Therefore, further steam heating must be carried out, through advanced steam pipes (superheater pipes) so that the steam is completely dry with a temperature of 260-280 0 C.
These advanced steam heating pipes are installed in the second combustion chamber, this results in wet steam flowing through the pipe to experience further heat.
- Water pipes
Water pipes function as a place for heating kettle water made as much as possible, so that heat absorption is more evenly distributed with high efficiency these pipes are divided into:
- A water pipe that connects the top drum with a face / back header
- Water pipes that connect the upper drum with the right / left side header
- Water pipes that connect the upper drum with the bottom drum
- Ash hopper
The ash which is carried by hot gas from the first combustion chamber is wasted in the disposal of cone-shaped ash.
- Air heater
The air heater serves to raise the temperature of the combustion air before entering the combustion chamber, that is by using the exhaust gas. Before the gas is discharged into the chimney it is first passed to the air heater, so that the heat in the exhaust gas is absorbed by the combustion air.
- Water header
Water header serves to hold water that will be evaporated by a water pipe, located around the combustion chamber. Water from the bottom drum is circulated to all headers, namely side headers, front headers, and rear headers.
- Further hot steam storage
This shelter serves to accommodate the hot steam generated from the evaporation process in the kettle
3.1.2 The main boiler helper equipment
In carrying out its functions, steam boilers are supported by several main auxiliary equipment, including:
- Force Draft Fan Primary (FDF Primary)
Primary FDF functions as an air puller or an outside air suction that will be injected into the combustion chamber or boiler kitchen. The outer air that will be pulled by the primary FDF is first heated with combustion gas which is in the air heater (air heater) so that the air needs in the kettle kitchen are already hot.
- Damper Unit Drive
The damper unit drive functions to regulate the air coming from the heater of the air exhaled into the combustion chamber.
- Iduce Draft Fan (IDF)
IDF functions as a gas suction from the combustion chamber and throws it out through the chimney.
- Bagasse feeder (pulp feeder)
Bagasse feeders function as feeders for the inclusion of pulp into the kitchen combustion kettle that is assisted by a screw feeder. The inclusion of pulp by Bagasse feeders is aided by a distribution water fan.
- Dust Collector
The Dust Collector serves to capture dust that flies with gas smoke.
- Tank dearator
Tank dearator serves to remove oxygen gas in the water and fill the initial heater by heating the kettle filler water using steam.
- Burner Oil
Burner Oil serves to cloud oil fuel which is aided by steam pressure and when it is ignited it is assisted by LPG.
- Air compressor
The air compressor functions to produce pressurized air which is then used for the pulverizing power of the boiler control instrument.
- Air Dryer (air dryer)
The air dryer serves to dry the air in the kettle.
- Oil Heater (oil heater)
Oil heater functions to heat residual oil fuel up to ± 80 o C before being used as boiler fuel.
- Forced Secondary Draft Fan (FDF Secondary)
Secondary FDF serves to draw hot air from the oil heater which is blown into the pulp in the air heater combustion chamber.
- Secondary air fan (secondary air fan)
Secondary air fan serves to blow the combustion air around the kitchen of the kettle with the aim that the combustion takes place perfectly.
3.1.3 Security tools
Given that the working pressure and boiler temperature are high, the kettle must be equipped with safety equipment as follows:
- safety valve
Safety shells used on Yoshimine Boiler type h-1600 It is the type of “per” full left that is designed so that lefting becomes smooth.
This tool works to remove steam at a predetermined pressure according to the valve settings on this tool. Generally a wet steam pressure safety valve (satured steam) is adjusted at a pressure of 21 kg / cm 2 while the safety valve of the steam pressure (superheated steam) is adjusted at a pressure of 20.5 kg / cm 2 . Adjustment of safety clash must be done by several people who are appointed to work for indications of pressure, pressure records and operations, and witnessed by a responsible person (Depnaker).
Things that need to be considered :
- Water levels that are too high when the safety wiring works must be avoided, because the steam used to open the shell contains a lot of water and will enter into safety shells.
- Do not tighten or loosen the safety shell lock nut without responsible permission (Depnaker).
- When the kettle is operating, try to keep the safety shells from working frequently. This will cause damage to the “disc” and weaken the pressure spring from the safety shell.
- Estimator glass
Estimator glass is a tool to see the height of water in the upper drum, to facilitate the control of water in the kettle during operation so that there are no greetings on the steam and water faucets in this tool, it is necessary to periodically attach water and steam to all faucets at least 3 (three) hours.
This estimator glass is equipped with an automatic controller which will ring the bell in the red light will turn on when there is a lack of water in excess of water, the bell will ring and the green light will turn on.
The glass of the estimator must always be kept clean and must be replaced if it has been dirty or blurred. The function of the glass estimator must be checked several times a day, this is to maintain the possibility:
- There is blockage on the connection pipes
- The occurrence of boiler water foam and water evaporation (priming)
The estimator glasses are checked according to the procedure below:
- Cover the top faucet and bottom faucet one by one
- Dispose of water from the column, glass estimator by opening the waste shells
- Open top shells (steam shells).
- Open the lower shells (water shells), the water will scatter from the waste shells to check the water pressure.
If the steam discharge power or water spraying power turns out to be weak or slow, then the channel has been blocked somewhere.
- Water sponge faucet (blow down valve)
This water spei faucet is installed in 2 (two) levels, a quick action valve and one screw thread. The material of the two faucets is made from materials that are resistant to pressure and high temperatures. When the boiler is fully operational it is necessary to do blow down, especially if the condition of the boiler filler water does not meet the specified standard, this will be better if more often done.
When doing a blow down, we must carefully pay attention to the condition of the water in the glass estimator. Each of us will blow down is not allowed to operate shells or other tools at the same time. The duration of the blow down depends on the condition of the water in the glass estimator. If we blow down it is not justified through the four headers at the time of the boiler and can cause further danger. Blow down through the four headers must be done every boiler will be operated, or when the boiler will stop operation and at the same time to reduce boiler pressure.
- Thermometer
This tool serves to find out the temperature of the water in the boiler, steam gas, steam temperature, and so on.
- Drain valve
This valve functions to drain or remove water in the drum. If the boiler water according to the analysis contains a lot of mud will be able to corrode the boiler pipes.
- Main steam faucet
The main steam faucet functions as a tool to open and close the steam flow out of the boiler installed in the main steam pipe. This tool is made from heat-resistant and high-pressure materials.
- Water intake faucet
The tap of the water intake consists of 2 (two) faucets, namely one screw faucet and one non-return valve.
- Alarm (alarm)
The alarm serves to provide an alarm to the operator about everything in the event of an abnormality in its operation, for example the fill water pressure is low, the working pressure exceeds the provisions of the vapor limit, and others.
- Others
Other equipment needed for steam boilers is:
- Dust blower on boiler water pipes (mechanical soot blower)
- Automatic boiler water input (automatic feed water regulator)
- Complete electric panels with measuring instruments
3.2 Steam turbines
Tool specification data:
Type: BGS-RY-K
Turbine speed: 7272/1500 rpm
Entry vapor pressure: 18 kg / cm 2
Outgoing vapor pressure: 101.2 / 1.0 kg / cm 2
Inlet steam temperature: 325 o C
Electricity generated: 3600 Kw
Steam consumption: 42 tons / hour
Channel diameter: 450 mm
Governor type: UG-4TO Wood Word Govern
Speed regulation: manual and motor governor
Critical speed: 2343 rpm and 4737 rpm
Drive type: electric motor
Round direction: clockwise
Bearing type: trust metal type
3.2.1 Steam turbine operations
To run or operate a steam turbine must know and understand several phases or stages, to avoid damage or workplace accidents.
- Preparation period
- Check valve position before inserting steam, lubricating oil, or cooling water.
- Check the level of the gauge on the oil tank.
- Check the oil and the gear side of the player’s house.
- Check the level of the gauge in the governor.
- Running period
- Open the main valve slightly for steam intake, if the vapor pressure has reached 18 kg / cm 2 and the temperature is ± 200 o C.
- Slowly open the emergency valve until the red light plate turns on and the stop of the main motor stops (turning motor) and the turbine speed will reach ± 100-200 rpm.
- Check the governor’s lubricating oil, oil pressure through the control glass.
- Slowly open the emergency stop valve, and turn the turbine up to 6800 rpm.
- The lubricating oil pump will stop automatically, then turn the switch in the automatic position, then the gear lubricant will be obtained by the gear pump.
- Steam valve cover (drain valve)
- Raise turbine rotation to 7275 rpm (normal rotation)
- Operation of the turbine from 0-7275 rpm takes 120 minutes (2 hours)
| Rotation (rpm) | Time (minutes) |
| 200 | 6 |
| 2000 | 50 |
| 3500 | 24 |
| 6800 | 38 |
| 7275 | 120 |
3.3 Maintenance and Maintenance of boilers
Boilers that play a role in the process of converting water into steam require special treatment and treatment. Problems that arise in boilers are generally caused by the treatment of boiler feed water that does not meet the requirements. For maintenance and maintenance of boilers can be done in the following ways:
- Initial Commissioning Process
- Operation in normal andemergency (emergency)
- Cleaning of boilers.
- Initial commissioning process
The initial preparation process that is carried out both on a new boiler or an old boiler is a main inspection consisting of the removal of scale or foreign material in the boiler after the hydrostatic test and inspection of the boiler leak. The kettle is operated by boiling using an alkaline solution to remove oil-containing materials and other deposits. During boiling, the boiler is operated at low pressure which is kept halfway from full pressure. Boiling time is approximately 24 hours. For cleaning high pressure boilers by reducing substances to remove scale. After acid cleaning or boiling ( acid cleaning ) the boiler is emptied, refilled and washed with fresh water.The boiler is then ready to operate at optimal vapor pressure and uses safety buttons.
- Operation under normal and emergency conditions
Operation under normal conditions is carried out by boiler factories that require maintenance and good boiler water conditions to prevent scaling or corrosion. To check properly / well, it is necessary to pay attention to the steam and temperature of the steam produced and maintain the cleanliness of the gas. The time period for starting and cooling the boiler after it is turned off, is set in the manual of the boiler and must be followed / followed properly.
Operation in an emergency is an important thing to note. This situation can be in the form of errors in the supply of feed water or fuel preparations. Air loss or fault in combustion fire. Modern boiler units are equipped with automatic safety locks for fuel supply flow and when the boiler stops operating, in the event of a hazardous situation.
- Cleaning of boilers
External cleaning is often done by curing and jetting gas or with running water.Internal cleaning with water and steam is done manually if possible and can also use chemical cleaners automatically for modern kettles in boiler units, especially in kettles which cannot be reached by hand.
Chemical cleaning must be carried out under the supervision of a supervisor.Most hydrochloric acids are used together with chemicals to remove hard crust. Acid cleansing if made by an incompetent person can cause excess chemicals in the boiler.After washing with acid, neutralized with an alkaline solution and the last time the boiler was operated on low pressure heating with an inert solution.
3.4 Maintenance and Maintenance Work Instructions
WORK INSTRUCTIONS FOR MAINTENANCE AND MAINTENANCE BEFORE THE BOILER OPERATIONS
| AIM : | PARAMETER | |
| 1 | Steam operates a boiler to produce steam | Dry vapor pressure 325 o C
Working pressure of 20-21 kg / cm 2 |
| NO | WORK SEQUENCE | IMPORTANT RESULTS /
THAT NEED TO BE WATCHED |
| 1 | Check before running that the estimator glass is working normally | The level on the glass is estimated at the upper drum at the position of NWL (normal water level) 50 mm H 2 O |
| 2 | Check the air compressor for instrumentation | Air pressure 7 kg / cm 2 |
| 3 | Check the electricity in the panels | Must be operational stand by |
| 4 | Check the residual pump pressure (if residual fuel is used) | Pump pressure must reach 12 kg / cm 2 |
| 5 | Check the damper By Pass gas duct | Must open 100% damper position
And the lid on boiler steam pressure is 17kg / cm 2 and opens the IDF damper |
| 6 | Check the valve air vent upper drum and super heater | Valve position must be 100% open
Closed at a pressure of 17kg / cm 2 |
| 7 | Check fuel (pulp and residue) | supply of fuel pulp and sufficient residue |
| 8 | Check the vacuum in the combustion kitchen | 10 mmH 2 O vacuum pressure |
| 9 | Check fill water and boiler feed water | Level on condensate tank min 600m 3
Temperature 90 o C |
| 10 | Check all valve main steam in HPSH | Open by pass main steam when steam pressure is 14 kg / cm 2 heating turbines and valve by pass cover if pressure has reached 20kg / mm 2
Ready to serve the needs of steam users outside the boiler |
Table 4.1 Maintenance and Maintenance Work Instructions Before the Boiler Operates
WORKING INSTRUCTIONS OF MAINTENANCE AND MAINTENANCE OF BOILER CONVEYORS
| AIM : | PARAMETER | |
| 1 | To carry pulp from the mill station and return from the pulp warehouse that goes into the boiler burning kitchen | |
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT NEED TO BE WATCHED |
| 1 | Check the electrical system to all panels | Starting from the power cable, fuse / fuse, indicator lights, on / off switch and ampere meter |
| 2 | Check all fastening bolts on the plight | Bolts must be really solid so as not to loose |
| 3 | Check all installed plights | Nothing is crooked |
| 4 | Check chain tension | In order to avoid the jump chain from the sprocket and broken chain |
| 5 | Check the lubrication system | Check periodic lubrication on bearings and chains |
| 6 | Operated conveyor sequences are carried out
a. Start conveyor receving b. Distributor start conveyor c. Start conveyor return d. Start conveyor elevator |
In order to avoid the accumulated pulp and there is no big shock of electrical power consumption |
Table 4.2 Work Instructions for Maintenance and Maintenance of Boiler Conveyors
WORK INSTRUCTIONS FOR WATER BOILER ANALYSIS
| AIM : | PARAMETER | |
| 1 | In order for the water filler and boiler water feed to meet standard requirements | |
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT NEED TO BE WATCHED |
| 1 | Analyze kettle filler water | pH (25 o C)
Total hardness (CaCO 3 ): <2 ppm Dissolved oxygen (O 2 ): <0.5 ppm Oil and sugar: 0 |
| 2 | Check the water supply in the tank 600m 3 | Sufficient water supply according to the operation of the kettle |
| 3 | Analyze boiler feed water | pH: 9-10
TDS: <3000 ppm Oil and sugar: 0 Temperature: 105 o C |
Table 4.3 Water Boiler Analysis Instructions
HYDROSTATIC TEST WORK INSTRUCTIONS
| AIM : | PARAMETER | |
| 1 | To find out the performance of the boiler after completion of repair / service equipment on the overhoule | Given a pressure of 0 and increased pressure, a 5-minute interval for each pressure increase of 5 kg / cm 2 is made to a pressure of 25 kg / cm 2 |
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT NEED TO BE WATCHED |
| 1 | Check man houle packing and hand houle on the header, upper drum and lower drum | There is no packing leak in the header, upper, lower drum, and handhoule in the header |
| 2 | Check all the bolts on the valve-valve | The bolts must be really solid to prevent leakage |
| 3 | Prepare water requirements for hydro test | Water on condensate tanks 200-400 m 3 |
| 4 | Charging water on the upper drum must be full | So that there is no air when given compaction pressure, waterslah does not occur |
| 5 | Check the packing, valve, water pipes for each additional pressure of 5kg / cm 2 , if it does not leak then continue to increase the pressure for the next interval | Check regularly for 5 minutes, see leaks |
| 6 | Every interval of increase in pressure and changes in decrease was recorded after being held for 5 minutes | If there is damage it will be repaired and the test repeated again |
Table 4.4 Hydrostatic Test Work Instructions
WORKING INSTRUCTIONS FOR BOILER TURBINE MAINTENANCE AND MAINTENANCE
| AIM : | PARAMETER | |
| 1 | To serve the boiler operation by turning the blower and boiler water pump | Temperature of 325 o C steam |
| Vapor pressure: 20-21 kg / cm
Rpm FDF / IDF turbine: 900 rpm Rpm FWP turbine: 2900 rpm |
||
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT NEED TO BE WATCHED |
| 1 | Change oil on the turbine | |
| 2 | Lubricate the bearing and runny with fat. | |
| 3 | Check the blades on the turbine | Dust and dirt. |
| 4 | Governoor oil change | |
| 5 | Check the pipes on the turbine | Make sure there are no leaks. |
| 6 | Check gasket and bolts on pipe joints. |
Table 4.5 Work Instructions for Maintenance and Maintenance of boiler Turbines
BOILER HEATING WORK INSTRUCTIONS
| AIM : | PARAMETER | |
| 1 | Boiler operating preparation | pH of fill water; 7, and 50% dry matter ingredients |
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT YOU NEED TO WATCH |
| 1 | Check the electrical system of all panels | Starting from the power cable and connecting cable, fuse / fuse, indicator lights, on / off switch and speed control switch |
| 2 | Check the boiler feed water supply | Amount of min water available 600 m 3 . On the condensate tank |
| 3 | Check the supply of fuel pulp and residue | Used for the combustion process in the boiler kitchen |
| 4 | Check the instrument compressor air | Air pressure must be 7 kg / cm 2 in order to fulfill instrument operation |
| 5 | Check the cooling cooling water supply | Has the water actually flowed from the output of waste water and the cooling water temperature max 34 oC on the meter, bearning-bearning turbines and pumps |
| 6 | Check kitchen boiler combustion chamber | Ensure that the dumping grate and pulp pass equipment on the feeder bagasse is good |
| 7 | Check conveyor chains | Sprocket, rails and chains have been tensioned and split pen then ready to operate |
| 8 | Check air / gas pass dampers | Make sure the damper bypass, IDF and FDF turbines have no air / gas leakage coming in and out |
| 9 | On heating / heating, carried out continuously / continius temperature and pressure / pressure increase regularly | Day 1-7, the combustion chamber temperature is controlled |
| 10 | Dilaksanaka soda boiling | Boiling soda is used to discharge / rinse the impurities in the chamber, headers and drums in the water boiler to the kettle and then circulate the water to get a normal pH (7) |
| 11 | Check the air vent valve | The air vent valve must be in an open position |
Table 4.6 Work Instructions for Boiler Heating
INSTRUCTIONS FOR WORK CARE AND MAINTENANCE OF WATER TREATMENT
| AIM: | PARAMETER | |
| 1 | To serve factory needs and boiler operations | |
| NO. | WORK SEQUENCE | IMPORTANT THING/
THAT NEED TO BE WATCHED |
| 1 | Cleaning the pond in raw water, SAND FILTER | Mud and plastic |
| 2 | Check the reactor tanks and remelter tanks | |
| 3 | Check tank softener | Cleanliness of cations and anions |
| 4 | Inspection of salt tanks | Tank leak |
| 5 | Check piping and valve | Porous and valve leakage |
| 6 | Check the pumps | Pump capacity and efficiency |
Table 4.7 Work Instructions for Maintenance and Maintenance of Water Treatment
Figure 4. Water treatment
CHAPTER IV
CONCLUSIONS AND RECOMMENDATIONS
4.1. Conclusion
After doing practical work for 1 month at PT. PERKEBUNAN NUSANTARA II KWALA MADU, conclusions can be drawn, namely:
- The purpose of doing practical work that has been achieved is to know the problems that exist in the boiler machine, namely in the process of maintenance and maintenance to be in accordance with procedures and standard boilers.
- For steam generators used boilers or steam vessels that have a working vapor pressure of 20 kg / cm 2 .
- When operating a boiler it is prohibited to set the unit settings to a positive scale because it will cause back fire.
- Feed water used for boiler purposes and the process must be neutralized at the water threatment station.
- The steam coming out of the turbine must be maintained so that condensation does not occur which causes the steam to not be used for the next process.
- Boilers as steam generators require special maintenance and maintenance.
4.2. Suggestion
- Machines that are used in the processing process must be carried out periodically to prevent problems / damage during the processing process.
- It is expected that field operators in providing information to students who are practicing correctly and clearly.
- Please recalculate the amount of fuel to be used so that there is no waste of fuel.
- Water used for boilers must meet the standards / criteria for boiler water so that the steam produced is according to standard.
- Prioritize K3 when operating and maintaining the boiler.
