HOW BOILERS WORK (BOILERS) ON SHIPS.
A. UNDERSTANDING BOILERS
On the tankers to support the smooth service and shipping required auxiliary aircraft include an auxiliary boiler which functions as a producer of hot steam which will be used to heat the cargo, pump out the cargo, heat the fuel, as an air temperature controller when we sailing in cold regions and used for other purposes. so the boiler is interrupted or damaged.
It is a fact that until now there are still many ships that use steam power installations, both the main installation and for the use of auxiliary aircraft. On steam tankers the results of these boilers are usually used as heaters, both fuel heaters, space heaters, water heaters, heating methods or for other purposes so that the ship’s operations can run smoothly.
Boiler or we may also call it a boiler is a closed vessel that can form steam with a pressure greater than the atmosphere by heating the boiler water in it with hot gases from the combustion of fuel. A boiler or steam boiler must be equipped with equipment that can help its performance so that the operational boiler runs safely. Boilers or boilers must have the following requirements:
1. Can produce steam with a certain weight in a certain time anyway, and the pressure is greater than one atmosphere.
2. The water content produced in the hot steam should be slightly raised.
3. Steam must be formed with the amount of fuel as economical as possible.
4. If the steam usage changes, the steam pressure must not change much
B. TYPES OF BOILERS AND ITS APPLICATIONS / EQUIPMENT
On motorboats the use of steam is of course only used on auxiliary aircraft. Whereas for steam ships, the main use of steam is to drive main engines, while other uses are for auxiliary aircraft. Therefore boilers or boilers can be distinguished according to the substances that flow into the pipes, namely:
a. Fire Pipe Boiler
Is a kettle in which the combustion gases flow inside the pipes and outside the water flows the boiler.
b. Water Pipe Boiler
It is a boiler in which boiler water flows inside the pipes while outside there are combustion gases.
We already know that the boiler must be equipped with apparatus and some equipment so that the boiler can run smoothly and to ensure the safety of the boiler. According to the steam law, what is included in the appendance is:
a. Related to the steam room.
– Security valve
This valve has a function to prevent the pressure in the boiler from exceeding the working pressure determined according to regulations.
– Main and auxiliary valves are valves used to regulate the provision of steam for heating the load, while auxiliary valves are used to regulate the flow to auxiliary planes. The valve must be installed as close as possible to the boiler and the valve must be able to open and close properly and smoothly.
This tool is to show and know the vapor pressure of the connection that is in a boiler clearly and precisely, with this manometer the operation of the boiler will be safer.
b. Related to the water chamber.
– Boiler filling valve The function of this valve is to regulate the amount of filling water entering the boiler and prevent boiler water from returning to the charging channel. § Spui faucet or Blow down.
Is to remove part or all of the boiler water to remove impurities that have settled in the bottom of the boiler.
Is as a controller of the water in the boiler.
Besides that, there are additional tools, but do not include the appendance, namely:
– Salt Faucet – Fire Line – Stamp
In modern boilers, besides these tools are still equipped with other tools to enhance the usability of the boiler, namely:
1. Advanced steam heater or OVO
2. Air heater or LUVO
3. Kettle or ECO filler water heater
C. BOILER OPERATIONS a. Operation Preparation.
1. Make sure that the tools below have been checked before operating the boiler.
2. Water Level Gauge or the
Drain Cock Water Level Guide must be fully closed as well as the top and bottom gauge cock of the water level instruction, ensuring that the desired water level of the boiler drum can be indicated by the water level indicator. However, the water level indicator shows that the water level must not be below the safe water level when there are periodic changes in the level of water to the increase in water temperature in the boiler.
3. Pressure Gauge. Make sure the Drain Cock is fully open and the needle shows zero. Pressure instructions are placed below so that it is easy to see.
4. Blow Off Valve or Blow Down Faucet.
Make sure the central faucet and blow down faucet on the ship are fully closed. Immediately take action that needs to be done if there is a leak in this system.
5. Water Feed Valve or Water Filling Faucet.
Keep the water filling stop faucet always open to add water at any time for the water level can be controlled. Close the filling water checking faucet so that there is no increase in the use of excessive filling water capacity.
6. Steam Stop Valve or Steam Stop Faucet. By opening or closing the faucet controller, make sure that the faucet is fully closed.
7. Safety Valve or Security Faucet.
Make sure there are no errors that occur in opening the divisor faucet manually (The Manual Valve Opening Device) and also the drain pipe on the body is opened.
8. Air Vent. Valve or Air Ventilation Faucet.
Open the air ventilation valve fully when the steam is first flowed, and close it again after that the air entering the boiler is discharged.
9. Other Units or Other Units.
Avoid errors during operation, check other units carefully and thoroughly.
b. Heating Fuel
One of the perfect requirements for fuel combustion is the existence of heating and good mixing between fuel and air as well as the appropriate heat. The purpose of holding heating to the fuel is:
1. So that the oil becomes runny so that it is easily separated or cleaned from dirt and achieves perfect fading viscosity.
2. With the highest temperature possible oil can be easily pumped up in combustion because of the already low viscosity, the oil removal will run smoothly and can be burned immediately.
Heating is carried out until it reaches a temperature of about 10 ° C below the flash point and its viscosity is approximately 2 ° Engler. If the heat exceeds the flash point, there will be difficulties during the journey to combustion due to high temperatures resulting in precipitation on the pipe which will be attached to the pipe so that it will reduce the pipeline.
3. Fuel Combustion.
Fuel oil basically contains the chemical elements carbon (C), hydrogen (H) and a little sulfur (S). Each of these elements in the combustion process with the element oxygen (O2) from the air will cause heat. In a simple chemical reaction in the combustion process can be written as follows:
C + O2 ® CO 2 + heat
2H2 + O2 ® 2H2O + heat
S + O2 ® SO2 + heat
From the reaction above it turns out that the combustion process produced H2O, namely water. This is what causes dissent over the amount of heat produced. To be able to achieve a complete combustion, the ratio between the amount of oil and air must be good. In order to obtain the perfect combustion needed:
1. The opaque kettle oil must be clean of any solid or liquid impurities.
2. Oil must be preheated to a certain temperature.
3. When leaving the combustion mouth the oil has sufficient speed and in a state of ignition can catch fire and will not hit the combustion wall.
4. The incoming air has sufficient speed and has a way of mixing with the fuel properly so that every part of the oil burns out. For this reason, the way to put air into the combustion kitchen is to follow the direction of a rotation, and the incoming air must be heated so that it can help the combustion.
d. Boiler Operation
1. Feed Water to the boiler or open water to the boiler
– Open all the filling water faucets from the cascade tank to the boiler as well as the air vents from the feed pump and the system.
– Turn on the source of canaga from the boiler.
– Move the filling pump from manual to automatic. Also choose pump filling No.1 or No.2.
– Press the button for the operation of the filling pump and make sure the pilot lamp lights up, the pilot lamp lights up for low water level also buzzer alarm low water level.
– Make sure the filling pump motor runs smoothly and the heat is not excessive.
– Make sure the compound gauge and pressure gauge are working normally
– Check the pipe system for leaks.
– Turn on the stop switch for a low water level buzzer alarm.
2. Air vents from the fuel circulation
– Open all fuel system faucets.
– Close the cock valve from the fuel return valve, also the ventilation air from the fuel system and filling pump.
– Raise the setting of the low temperature thermostat alarm according to the circulation of the fuel.
– Move combustion to automatic operation and move the combustion switch to the ON position.
– Open air vents on the fuel return pipe for all exhaust air from the system.
– Check the fuel system for leaks.
– Make sure the fuel pump motor and fan force drop are running soft and the heat is controlled.
– Make sure that the thermometer records according to the temperature of the fuel heating and there are no leaks as it passes through the nozzle pipe.
– If the heating temperature of the fuel is suitable and there are no problems in each unit, turn on the alarm thermostat at normal temperature.
– Discharge of water every 35 minutes.
– Combustion starts a few seconds after the burning pilot lamp lights up.
– Checks on combustion
– Color, ignition level and ignition stability
– Color of smoke, exhaust gas leaking from the top and protection.
– Vibration is not normal.
– If a problem occurs, stop burning immediately and check the oil pressure, oil temperature, and nozzle tip.
– Open the main steam valve slowly to prevent water tapping in the system.
– Check the system for leaks
4. Shut down or drain
– Increase in steam pressure close to maximum normal working pressure
– Close the main steam faucet, blow off the surface of the water.
– Combustion is turned on again, close to the maximum normal working pressure.
– Turn off the combustion switch, press the shutdown lock and disconnect the power source.
– Close the filling system faucet, check the water level in the cascade tank from the amount of oil in the daily tank – – before closing the main valve.
5. Cold starting or running in cold conditions
When the vapor pressure falls to zero or in particular in this case a trial operation or a new boiler, pay attention to the following:
– Since the inside of the cold boiler avoids the ignition of sudden ignition. Don’t start the steam pressure suddenly but take a good time until the pressure rises to 1 Kg / cm².
– Check all systems and take the necessary actions to prevent things from being desired.
D. CORROSION ON BOILERS
a. Form of Corrosion in Boilers.
In this chapter various forms of corrosion will be described in the boiler. Corrosion can occur on the water side and on the flue gas material. What is meant by corrosion is the contact that is not preferred to the material by the chemical influence on the surface. Corrosion on the water side can be prevented by handling water well, while corrosion on the gas side is more complicated. Prevention is mainly located in the field of construction, in the sense of the word in the form of a boiler, the pattern of piping, the location of advanced heating, temperature regulation of the smoke gas cooler, and so on. The design of boilers today mainly shows the prevention of corrosion on the side of the flue gas.
Except for precious metals gold, silver and platinum metals found in nature as oxide, in the sense of the word compound with acids. The processing of pure metals for practical applications takes place through the following reduction processes:
MeO + R ® Me + RO
MeO is metal oxide, R reduction means, Me metal and RO oxide reduction facilities. For example the reduction of Fe2O3 with CO, as it takes place in a high kitchen is as follows:
Fe2 O3 + 3CO ® 2Fe + 3CO2
Although most metals are not in their pure form but are applied as alloys, they will try to return to their original form, oxide. Because of that oxide is considered a natural symptom. Eradication every year requires huge costs for repairs and means of eradication on the one hand and material losses on the other. Corrosion can be divided in terms of its manifestations, namely:
1. Touching on all surfaces.
2. Local contact (formation of puddles, grooves).
3. Line between crystals, i.e. touching at the crystal boundaries at or near the subsurface.
Other parts are according to the mechanism of corrosion:
1. Pure chemical corrosion.
2. Electro-chemical coreso
b. Causes of Corrosion in Boilers
1. Corrosion caused by boiler water
Corrosion will occur in the part where water is continually evaporated when the smoke funnel is above the combustion chamber and shows the water pipe leading to the combustion chamber, when some corrosion occurs immediately overcome by chemical reactions, when the reaction is rapid the corrosion does not take root. If, however, washing with a chemical reaction will slow corrosion. Some of the causes of corrosion are negligence in blow off, unclean cleaning in the boiler, insufficient circulation of boiler water and excessive use.
2. Corrosion caused by other substances
a. Gas reaction in boiler water
Corroded or corroded iron due to being submerged in water or high temperatures and the use of corrosive materials. In this case the oxygen contained in the water supply is very good for burial or perforation, this incident is the inside of the steam room where there is a lack of water change, running water from the drum boiler and pipes, water pipes and economiser. Carbon acid results from carbon dioxide when dissolving in water and reacting with iron to produce carbon iron. Iron carbon reacts with oxygen to produce a second iron oxide. Since this reaction process has taken place where carbon dioxide has been released, it has accelerated other corrosive cycles.
b. Corrosion by nature
One part of burial or hollowing, the expansion of the corroding area is caused by the separation of acids in boiler water and the separation of large / fatty acids from animals or woven plants in boiler water.
c. Corrosion by salt
Corrosion of magnesium chloride in the boiler occurs until it takes root. This is due to the separation of the hydrochloric acid results in boiler water and this does not stop in perforation but stops in the form of rust as the fish scale expands, which often occurs in parts indicating for strong heat where air bubbles are difficult to release.
d. Corrosion by excessive hot steam.
Steam is a separator in hydrogen and oxygen when the temperature of the steel surface rises to 400 degrees centigrade or higher. Oxygen is the corrosion of a steel cross section.
E. AIR BOILERS AND AIR BOILERS
a. Understanding boiler water and boiler fill water
We need very pure water to fill the boiler and to add to the effects of leakage that occurs in the circulation of a circle that is heating – evaporating – condensing with the intention of giving energy. For this purpose a variety of aircraft are available in the circumference of a circle namely a steam boiler – turbine – condenser and other auxiliary aircraft such as pumps, charge heaters, fuel heaters and so on.
During circulation there is a 2% water loss, this loss must be compensated. On ships, this is done by evaporation of sea water. The vapor is condensed again and as distilled water is stored in a supply tank, from the tank is put back in the circumference of the circle but many ships still take stock of boiler fill water from land.
So the understanding of boiler fill water is water that is provided to add boiler water that has been lost in circulation. Whereas boiler water is water that has participated or experienced circulation in the cycle of steam, until it is condensed, and becomes steam again.
b. Requirements for boiler fill water
In principle, fill water must meet several requirements, namely:
– As far as possible O2 and CO2 gas is limited, which dissolves in boiler water causing oxidation reactions to metals or iron pipes in the boiler.
– Kitchen salt levels (NaCl and Na2SO4) are as low as possible because this salt causes boiling water to boil.
– If boiler fill water is deposited, it must be in a condition that can be removed from the boiler.
– Fill water should be non-aggressive on iron, tend to be Ph toward bases.