Steam Boilers and Thermal Oil Boilers on Ships
1. Steam Boiler
System steam boiler tebagi on a feed water system, steam system (steam) and the fuel system (fuel). The feed water system supplies water to the boiler automatically and according to the steam boiler requirements. A variety of faucets are provided for maintenance and repair needs with (example: blowdown). The steam system combines and checks the production of steam in a boiler.
Steam moves across the pipeline system to the point of use. In the whole system, st
eam pressure is controlled using a faucet and monitored by a pressure monitor. The water supplied to the boiler to convert to steam is called feed water. Feed water comes from two sources, namely condensate or steam which condenses back from the process and raw water
already processed which must be fed from outside the boiler room from the plant system. To produce a higher boiler efficiency, using an economizer to heat feed water initially uses waste heat in the exhaust gas. The fuel system is all the equipment needed to supply fuel to get the desired heat. Equipment needed in the fuel system depends on the type of fuel used by the system.
The working principle of a steam boiler
After going through the process that was done before working on the core process (pretreatment) in condensate water, the feed water is pumped to the economizer. In the economizer the preheating takes place using the exhaust heat in the chimney. Preheating is done to increase the efficiency of the boiler. Then the feed water enters the boiler, before the feed water is given chemichal according to a predetermined dose And the feed water that gets warmed up in the boiler turns into a steam stage and is ready to be shared
After the steam changes the stage back to condensate water, it can be pumped back into the boiler again. Condensate water is only used to replace the loss of water due to the blowdown process
a. fuel analysis.
For comparable designs and purposes, the reference standard for fuel oil is = 6 fuel oil (6 fuel oil (bunker C) which has the following characteristics:
The heating value which is higher than the fuel reference standard is determined by a calorimeter bomb and corrects for specific heat at a constant pressure of 18,500 Btu / Lb. the base temperature for the heat content is estabilished like 100F. For a balanced heat design and calculation the heat value from oil correction for additional heat added (in Btu’Lb) in heating the oil to the assumed temperature (200F) (which) is important for fogging according to the following expression:
Added heat = 0.46 (parse to atom temperature -100F)
the total heating value (concerning) the reference oil is, therefore, 18,546 Btu / Lb and is used for all types of extraction which includes vaporizing fog.
b. Air Combustion
oxygen is needed for combustion provided by combustion air. Other elements of air act as diluents. air is a mixture – as distinguished from a chemical mixture – of oxygen, nitrogen, and small amounts of carbondioxide, water vapor, argon, and other noble gases. the basic composition of dry air for combustion purposes is considered as:
gas which is rarely included as part of the elemental limp.
air is assumed to be supplied to the forced draft a temperature of 100F, a relative humadas family of 40 percent, and a barometic pressure of 29.92 in Hg. under the air such conditions have the following physical properties.
based on the fuels listed ahead and their standards, the analysis will show the stoichiometrical state or the quantity of dry air theoretical to burn one pound of fuel is 13. 75 lb. From this, the following amounts of water for various excess percentages are determined:
The final analysis of the fuels that are actually found in the variation of the standard reference fuel. illustrate 17 shows the effect of this variation on the theoretical air required for combustion. for example, a fuel consisting of 87.25C, 12.0 H2, 0.2S, 0.4o2 and 0.15N2 will require 3.0 percent more air for stoichiometric combustion (+ 3.8% for H2, – 0.4 forC, – 0.4% for S) 
To reduce dry gas heat losses that are stacked up, the weight of the gas funnel must be held to a minimum consistent with the provision of enough air to completely burn the fuel. recognize that up front, an operator needs to observe the resultwith certain fuel oil bunkered and make excess air adjustments to achieve complete combustion. however, in the case of mose, the design of a boiler is based on an air-fuel ratio sufficient to provide 715% excess air.
while many oil burners and combusition control systems can operate successfully with excess air, use 15% for design purposes to ensure sufficient surface heat transfer and force draft to blow with sufficient capacity. for / due to additional margins,
Comparison of air fuel or excess air is often discussed in the case of CO2, which is readily obtained from a boiler operation on the aid of an analysis system. an orsat reading 14% Co2 corresponds to approximately 15% excess air. illustrate 18 shows of the relationship between Co2, O2 and excess air.
such as heat transfer and draft calculations are based on the weight of the gas flue air weight, use of the term “percent CO2” which is a volumetric measure of importance only in comparing the performance of oil burners. It is most useful where oil is used to be widely used in various analyzes of the standard fuel reference. The excess air, or air fuel ratio, can also be determined conviniently by using an oxygen analyzer, a reading of 3% oxygen corresponding to approximately 15% excess air.
The efficiency of the boiler is described as a comparison of the heat input. heat output is equivalent to heat entering less that loss.
Heat output can also be defined as the difference in enthalpy between feed water entering the boiler or economizer, if installed, and steam leaving the boiler (both superheated and desuperheated). When a steam air heater is installed, the heat input from steam is charged to the total boiler heat input and the efficiency becomes:
Efficiency = Hi + Ha- HLHi + Ha
Where heat Ha is added above 100 F to the combustion air by the heater Where heat Ha is added at the beginning of the design process, one of these expressions is solved for heat input Hi, from which the weight of the fired oil is easily determined by dividing by the heat value of the fuel design, usually 18,546 Btu / lb. All amounts are determined based on hourly flow rates.
The efficiency of a boiler required is usually determined by specifications or heat balance. Along with the design steam pressure and temperature, it sets the number and oh settings of the heater surface mounted on the boiler and economizer. The design of the vapor pressure and saturation temperature is set according to the “sink” the effective temperature of the boiler generating bank, and the feed water sets that of the economizer.
In the case of an air heater installation, the sink is the inlet air temperature for it, usually 100 F. The typical curve of efficiency versus load for the steam generator is shown in Fig.19. Note that efficiency decreases with increasing steam output. The quantity of hot exhaust gas which will increase is cooled as more fuel is consumed to increase steam output.
As it happens, the effectiveness of a fixed amount of heating arises shrinkage and efficiency decreases. This is common to the surface size of boilers for commercial vessels where desired efficiency is ranked in relation to “ABS power”. Efficiency at maximum or minimum speed figures is then a function of this design point and must be at the efficiency of the characteristic curve.
A practical ceiling on boiler efficiency is imposed by the need to maintain the temperature of the uptake of gas above the dew point of the chimney gas. This minimizes the connection of sulfur deposites and corrosion from the cold end of the heat exchanger and ductwork. In economizers, corrosion results in leakage and cormorant forced outages; therefore, it is common practice to maintain at least maintaining feedwater temperatures of about 280 f, which results in a chimney gas temperature from about 315 to 320 f and limits the risk of corrosion.
In a rotating regenerative air heater, a corrosion failure is not due to non-catastrophic properties; therefore, a low temperature stack (280 f or less) is practical and boiler efficiency is obtained higher. Cycle efficiency can be further improved through the use of payment water heaters to force the altitude to provide feedwater at temperatures which are practically not high on a recurring economizer.
d. Selection of oil combustion
The choice of type and number of oil combustion used is dependent on the available draft loss, the dimensions of the furnace, and the ranking fairing boiler. High capacity, wide range burners are usually selected for installation by reducing the number of burners require and simplifying maintenance and operation. The costs of controls and safety equipment, such as maintenance, must therefore be maintained at least.
The size and arrangement of the engine room often affects the location of the burner. It is desirable to place the burner close to the control console for ease with visual monitoring and availability. In both drum boilers, burners can be installed in front of a fireplace for a wall, roof or side wall.
In front of the boiler, the gas shot latitude is parallel to the boiler bank.
They compared temperatures of 90-deg directing into the screen rows, and as the depth of the hearth furnace is usually the shortest dimension the gas tends to hoard based on the back of the wall. This heavy concentration of gas is behind the confusion of the gas temperature, and making predictions from the temperature of the water vapor and the metal tube superheater temperature is more difficult.
On the other hand, with the roof firing uniformly distributed gas over the depth of the boiler. Since heigth hearth furnaces are usually the longest dimensions, there is less tendency to concentrate the gases before they direct into the filter superheater.
Side firing, with burners on the sidewall, requires that careful attention be given to design details. Since the gas process has no rotation before entering the screen, making the limp tends to be very long long. This can result in a flashing of the screen and superheater bank with one advers effect on the superheater temperature tube and the stearn temperature.
We usually, at least two oil burners are used so that one burner can be shot when cleaning or changing older brothers in the other.