BOILER OPERATION PDF
PDF Drive is your search engine for PDF files. As of today we vii This book is written for the boiler operator, an operating engineer or stationary engineer B. How an industrial boiler system works. 8. The use of . operation. Steam boilers on the other hand are only 3/4 filled with water; the upper quarter is the steam. SE TITLE. The Basics of Boiler Operation and Maintenance. Part. 2, Air Pollution Training Institute. Self-Instructional Course SI INSTITUTION.
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participate in an examination and obtain a boiler operator license as required operating pressure on the boiler by regulating the burner to the steam pressure. By Superior Boiler Technologies. OPERATIONS. AND. MAINTENANCE. MANUAL. LOW AND HIGH PRESSURE STEAM BOILERS. Series through Series. iv. Library of Congress Cataloging-in-Publication Data. Heselton, Kenneth E., Boiler operator's handbook / by Kenneth E. Heselton p. cm. Includes index .
The length and frequency of the blowdown is particularly important when the suspended solids content of the water is high. With the use of frequent short blows, a more uniform concentration of the pressure vessel water is maintained. In cases where the feedwater is exceptionally pure, or where there is a high percentage of return condensate, blowdown may be employed less frequently since less sludge accumulates in the pressure vessel.
It is generally recommended that a steam boiler be blown down at least once in every eight-hour period, but frequency may vary depending upon water and operating conditions. The blowdown amounts and schedule should be recommended by your local Cleaver-Brooks authorized representative.
A hot water boiler does not normally include openings for surface blowdown and bottom blowdown since blowdowns are seldom practiced. Always be alert to system water losses and corresponding amount of raw water makeup.
A water meter is recommended for water makeup lines. Proper blowdown is performed as follows: Blowdown should be done with the boiler under a light load.
Open the blowdown valve nearest the boiler first. This should be a quick-opening valve.
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Crack open the downstream valve until the line is warm. Then close it quickly being sure that the handwheel is backed off slightly from full close to relieve strain on the valve packing. Close the valve nearest the boiler. Repeat the above steps if the boiler has a second blowdown tapping. Water columns should be blown down at least once a shift to keep the bowls clean.
Care should be taken to prevent low water shutdown if this will affect process load. Please keep in mind that all blowdown piping should be checked once a year for obstructions. Blow Down Purpose The purpose of blow down is to control the amount of solids and sludge in the boiler water. The blow down process involves partially draining the boiler to remove sludge and to maintain pre-determined concentration levels of solids.
As the water is turned into steam, the solids remain behind. On hot water systems, there is generally no make-up water. Therefore, the solid concentration remains constant and no blow down is needed.
The amount and frequency of blow down differs for each boiler application and should be determined by your water management consultant. Blow down is affected by the type of boiler, operating pressure , water treatment, and the amount and quality of make-up water. Blow down piping should be at least the same size as the blow down tapping on the boiler. Blow down valves should be sized in accordance with the ASME code and piped to a safe point of discharge.
There should be either two slow opening valves or one quick opening valve and one slow opening valve piped in series. A slow opening valve is defined as needing five complete degree turns to go from fully closed to fully open.
A quick opening valve goes from fully closed to fully open in one complete motion.
In the case of one quick and one slow opening valve, the quick opening valve should be located closest to the boiler. If possible, the blow down valves should be piped on the same side of the boiler as the water column gauge glass. To blow down the boiler: Open the quick opening valve valve closest to the boiler first. Open the slow opening valve last. Blow down the boiler for the required amount of time, per your water management consultant, by opening and then closing the slow opening valve.
Feed water system, Steam system and fuel system. A typical boiler room schematic is shown in Figure 1. Various valves provide access for maintenance and repair.
Steam is directed through a piping system to the point of use. Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges. The 3 Fuel system includes all equipment used to provide fuel to generate the necessary heat.
The equipment required in the fuel system depends on the type of fuel used in the system Feed water: The water supplied to the boiler that is converted into steam. The two Sources of feed water: It is the condensed steam returned from the processes. Water which must come from outside the boiler room and plant processes. Boiler Specification The heating surface is any part of the boiler metal that has hot gases of combustion on one side and water on the other.
Any part of the boiler metal that actually contributes to making steam is heating surface. The amount of heating surface of a boiler is expressed in square meters.
The larger the heating surface a boiler has, the more efficient it becomes. The quantity of the steam produced is indicated in tons of water evaporated to steam per hour. The boilers at Pakistan steel are water tube boilers that generate high pressure superheated steam by burning natural gas, blast furnace gas, coke oven gases, and coal tar in boiler furnace.
The basic purpose of installing these boilers is to utilize by products generated at blast furnace and coke oven batteries, which having high calorific values; if not utilized will go waste in environment, and fulfill electricity demand of Pakistan Steel. There are four boilers installed at TPP in series, all are of same configurations. Following are the specification of boilers: In the upper part of furnace and in turning gas duct a platen part of supper heater is arranged.
Following is the brief construction of boiler.
Furnace combustion chamber: Combustion Chamber consists of following sections: The vacuum type furnace is divided into two sections upper and lower. Similarly in the lower section two for each blast furnace gases and coal tar burning.
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Water Walls Tubes: The furnace refractory linings are covered with water wall tubes from bottom to the top and these water walls are connected to boiler drum at the top.
These water wall carbon steel tubes have O. D of mm and wall thickness of 10 mm. Convective Shaft: Various sections of Convective shaft and their functions are as follows: Steam from the boiler drum first enters in the sealing tubes alloy steel , these tube covers the whole roof of gas duct. Both sealing and turning tubes have O. D of 32 mm.
Screen Super heater tubes: Screen type super heater consists of two rows of vertical screens 16 screens in each row. Convective 1st stage super heater: Saturated Steam from screen super heaters collects into headers, where it gets uniform temperature and then enters into 1st stage convective super heater tubes alloy steel and becomes superheated steam.
These tubes are positioned in horizontal direction. These tubes are supported by suspender tubes with the help of attached heat resistant welded steel hooks.
Convective 2nd stage super heater: In both super heater stages tubes are arranged in U-shape two loops configuration. Economizer tubes: These tubes are positioned in horizontal direction in lower portion of convective shaft. Function of condenser is to form condensate for de super-heaters. It consist of cylindrical steel shell in which feed water tubes are passing through, and is connected to boiler drum by two pipes through which steam is provided.
Here steam transfers its energy to feed water, it gets preheated, and steam condensates to liquid water which is free from all impurities. Boiler Drum: Steam goes to super heaters and water to drum and is recycled. In all there are 39 cyclones. Water volume of drum is divided into two sections namely: The feed water is let into the clean section only. The feeding of salt section is realized with boiler water of clean section through the holes in partition.
Table 1: Steam Ultimate Temperatures: When water is boiled and steam is generated, any dissolved solids contained in the water remain in the boiler. If more solids are put in with the feed water, they will concentrate and may eventually reach a level where their solubility in the water is exceeded and they deposit from the solution. Above a certain level of concentration, these solids encourage foaming and cause carryover of water into the steam. The deposits also lead to scale formation inside the boiler, resulting in localized overheating and finally causing boiler tube failure.
It is, therefore, necessary to control the level of concentration of the solids and this is achieved by the process of 'blowing down', where a certain volume of water is blown off and is automatically replaced by feed water - thus maintaining the optimum level of total dissolved solids TDS in the boiler water. Blow down is necessary to protect the surfaces of the heat exchanger in the boiler. However, blow down can be a significant source of heat loss, if improperly carried out.
The maximum amount of total dissolved solids TDS concentration permissible in various types of boilers is given in Table 2.
Low pressure Water tube boiler 3. High Pressure Water tube boiler with superheater etc. Package and economic boilers 3, ppm Conductivity as Indicator of Boiler Water Quality Since it is tedious and time consuming to measure total dissolved solids TDS in boiler water system, conductivity measurement is used for monitoring the overall TDS present in the boiler.
A rise in conductivity indicates a rise in the "contamination" of the boiler water. Conventional methods for blowing down the boiler depend on two kinds of blowdown - intermittent and continuous.
A boiler is the sump of the boiler system. Water is the most important raw material on earth. Not only does it maintain life, it is also used for transportation, it serves as a solvent and it stores energy. Pure water H20 is tasteless, odorless and colorless in its pure state; however, pure water is very uncommon. All natural waters contain various types and amounts of impurities. When it percolates through the upper layers of the earth to the ground water table or flows over the surface of the earth dissolving and collecting additional impurities.
These impurities may form deposits on heat transfer surfaces, causing metal corrosion, reduction in heat transfer and associated overheating with loss of mechanical strength.
As shown in Table 1, together with their technical and commonly used names, chemical symbols and effects - the common impurities in raw water are: Scale forming substances; the principal ones are the carbonates and sulphates of calcium and magnesium. Not all dissolved solids will form scale. Silica forms scale in a similar way to the permanent hardness salts.
When the scaleformed is a mixture of silica, calcium and magnesium salts, it is very hard and therefore presents a difficult problem at inspection time Suspended Solids: Sludge forming substances; usually solid mineral or organic particles carried in suspension.
In an action often called ''modulation'', the plug or similar element is shifted to increase or decrease available flow area. Flow through a particular size of open orifice area is primarily dependent upon the available pressure difference.
Where the managed parameter is pressure , obviously, flow and pressure are interdependent.
Boiler Operator Study Guide.pdf
Essentially, the regulator must be able to influence pressure at the measured point and must exercise that influence in the appropriate direction of response.
Where the managed pressure is upstream from the regulating valve, you normally would want the valve to open to permit flow as pressure begins to rise.
Finally, regulators often are called upon to manage operating conditions other than pressure, such as temperature or flow. A regulator will be either direct- or pilot-operated. Direct-operated regulators are simple, single-minded devices intended for a specific application within a particular range of pressures. Direct-Operated Regulator In a direct-operated pressure regulator '''Figure 19''' , managed pressure is applied to some internal surface within the valve.
The resulting force is transmitted to the modulating parts of the valve and balanced by a second force applied within the valve. In many cases, the second force is adjustable to establish the setpoint. Movement of the modulating parts inherently involves a change in the balanced forces and thus a change in the managed pressure.
The more the demanded flow deviates from what the regulator was experiencing at the time it was first adjusted, the more the pressure must deviate from setpoint.
Two flows are managed by the valve. The first, which is by far the greater proportion of the total flow, is managed by the plug and orifice in the slave section.
The second, the pilot stream, is managed by the pilot section. The pilot section may have its inlet connected to the immediate upstream side of the main valve or may source its flow from a higher pressure space.
The purpose of boiler blowdown is to control solids in the boiler water. Blowdown protects boiler surfaces from severe scaling or corrosion problems that can result otherwise. There are two types of boiler blowdowns: ''continuous'' and ''manual''.
A continuous blowdown uses a calibrated valve and a blowdown tap near the boiler water surface. As the name implies, it continuously takes water from the top of the boiler at a predetermined rate. A continuous blowdown is an optional feature and may not be included on your steam boiler; however, all steam boilers should include a means for manual blowdown as standard equipment.
Manual blowdowns are accomplished through tapings at the bottom of the boiler. These openings allow for the removal of solids that settle at the bottom of the boiler.
Manual blowdown is also used to keep water level control devices and cutoffs clean of any solids that would interfere with their operation.
All steam boilers require manual blowdown whether or not they are supplied with continuous blowdowns. Frequency of Manual Blowdown When continuous blowdown is used, manual blowdown is primarily used to remove suspended solids or sludge.
The continuous blowdown removes sediment and oil from the surface of the water along with a prescribed amount of dissolved solids. When surface or continuous blowdown is not used, manual blowdown is used to control the dissolved or suspended solids in addition to the sludge.
From the standpoint of control, economy, and results, frequent short blows are preferred to infrequent lengthy blows. The length and frequency of the blowdown is particularly important when the suspended solids content of the water is high. With the use of frequent short blows, a more uniform concentration of the pressure vessel water is maintained. In cases where the feedwater is exceptionally pure, or where there is a high percentage of return condensate, blowdown may be employed less frequently since less sludge accumulates in the pressure vessel.
It is generally recommended that a steam boiler be blown down at least once in every eight-hour period, but frequency may vary depending upon water and operating conditions.The EJA and EJX Series of Differential Pressure Transmitters are capable of measuring the drum level with high stability even in actual applications at high temperatures and high pressures.
Poor care of the fireside mainly when burning oil , and loss of heat through un-insulated or poorly insulated surfaces are also big sources of efficiency losses, but not as significant as waterside losses. As the seat area usually defines the load transmitted to and from the spring, very high precision is essential to ensure proper valve operation. Frequency of Manual Blowdown When continuous blowdown is used, manual blowdown is primarily used to remove suspended solids or sludge. Most designs incorporate a plug or similar element that occupies a portion of a stationary orifice while throttling.
Ultraviolet UV Light sensors that detect ultraviolet radiation emitted from all flames 5.
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