WorksheetsPower Plant Steam
Total questions: 100
Worksheet time: 1hrs 19mins
The (a) is the fundamental operating cycle of all power plants where an operating fluid is continuously evaporated and condensed. The selection of operating fluid depends mainly on the available temperature range.
The vapor is expanded in the turbine, thus producing work which may be converted to electricity. In practice, the expansion is limited by the temperature of the cooling medium and by the erosion of the turbine blades by liquid entrainment in the vapor stream as the process moves further into the two-phase region. Exit vapor qualities should be greater than 90%.
Isobaric Heat Transfer
Isentropic Compression
Isentropic Expansion
Isobaric Heat Rejection
The vapor-liquid mixture leaving the turbine (4) is condensed at low pressure, usually in a surface condenser using cooling water. In well designed and maintained condensers, the pressure of the vapor is well below atmospheric pressure, approaching the saturation pressure of the operating fluid at the cooling water temperature.
Isobaric Heat Transfer
Isentropic Compression
Isentropic Expansion
Isobaric Heat Rejection
The pressure of the condensate is raised in the feed pump. Because of the low specific volume of liquids, the pump work is relatively small and often neglected in thermodynamic calculations.
Isobaric Heat Transfer
Isentropic Compression
Isentropic Expansion
Isobaric Heat Rejection
It is the network produced in the Rankine cycle is represented by the area of the cycle process. Obviously, this area can be increased by increasing the pressure in the boiler and reducing the pressure in the condenser.
(a)
The high combustion temperature of the fuel is better utilized if a gas turbine or Brayton engine is used as "topping cycle" in conjunction with a Rankine cycle. In this case, the hot gas leaving the turbine is used to provide the energy input to the boiler. In co-generation systems, the energy rejected by the Rankine cycle is used for space heating, process steam or other low temperature applications.
Feed Water Preheating
Pressure Difference
Superheating and Reheating
Combined Cycles
The cold liquid leaving the feed pump is mixed with the saturated liquid in the boiler and/or re-heated to the boiling temperature. The resulting irreversibility reduces the efficiency of the boiler. According to the Carnot process, the highest efficiency is reached if heat transfer occurs isothermally. To preheat the feed liquid to its saturation temperature, bleed vapor from various positions of the turbine is passed through external heat exchangers (regenerators).
Feed Water Preheating
Pressure Difference
Superheating and Reheating
Combined Cycles
What is a Prime Mover?
(a)
The raw water, softened water or demineralized water required for steam generation i.e. water from our very own "DISTILL WATER TANK".
CONDENSATE WATER (CW)
FEED WATER (FW)
BLOWDOWN WATER (BW)
MAKE-UP WATER (MW)
After the Heat transfer process of steam in heat exchangers or heating coils, the steam reverts back to its liquid phase.
CONDENSATE WATER (CW)
FEED WATER (FW)
BLOWDOWN WATER (BW)
MAKE-UP WATER (MW)
FEED WATER (FW) is (a) .
Water which is present in the steam generating section of the boiler.
CONDENSATE WATER (CW)
FEED WATER (FW)
BOILER WATER (BW)
MAKE-UP WATER (MW)
Hard Water contains an appreciable quantity of dissolved minerals. Hardness is primarily composed of?
(a)
Alkalinity is measured by a process known as (a) .
What makes Alkalinity? Choose three correct answers.
Hydroxide
Bromide
Phosphate
Silicate
Oxate
pH is also referred as?
(a)
(a) ranges from 0 to 14 with 0 being most Acidic and 14 being most basic of alkaline. Therefore 7 being the mid value simply illustrates value of neutral.
Explain what is Total Suspended Solids (TSS).
(a)
This represents dissolved constituents, e.g. calcium, Chlorides, Sodium, etc. It is measured in mg/L.
Total Cations
Total Dissolved Solids (TDS)
Total Suspended Solids (TSS)
Total Solids
Finely suspended matter which does not settle and impart a muddy or cloudy appearance to water.
Dissolved Gases
Turbidity
Total Anions
Total Solids
It represents the sum of TSS and TDS.
Dissolved Gases
Turbidity
Total Anions
Total Solids
Cations are positively charged metallic parts such as Mg++, Ca++, Na+, K+ etc and are attracted to cathode.
Dissolved Gases
Turbidity
Total Cations
Total Solids
Anions are negatively charge non-metallic parts such as alkalinity i.e bicarbonates, carbonates, chlorides, sulphates, etc and are attracted towards anode.
Dissolved Gases
Turbidity
Total Anions
Total Solids
(a) is a measure of water's ability to conduct electricity in cooling water. It indicates the amount of dissolved minerals in water. It is measured in Micro ohms.
(a) can exist in water as an emulsion.
(a) can exist in water as a dissolved cation.
Normally exists in water as an anion or as a colloidal suspension. Measured in mg/L or Sio2.
(a)
There are three main problems which water can incur in Boiler systems. These problems are?
(a)
As stated earlier Calcium, Magnesium and silica when heated, precipitate out to form a dense coating of minerals on the water side of the boiler. This layer of coating is technically called (a) .
The following are thge principle factors which contribute to the formation of scales, except
Insufficient Blowdowns
Low condensate recirculation
Low alkalinity of water
High operating temperatures
A trend showing an increase in flue gas temperature over a period of time depicts the presence of scale
Flue gas Temperature
Fuel Consumption
Visual inspection
Condensate water is very pure and free from hardness causing minerals. Make up water on the other hand has impurities. As learnt before Boiler Feed Water is the sum of make up water and condensate water. So lesser the amount of make up water we add lesser the quantity of impurities being introduced to the system. To get maximum condensate back in the hotwell it is very important that we keep the steam system free from leakages and keep dump condensor in good working condition.
(a)
Name the two methods of Internal Chemical Treatment.
(a)
(a) is deterioration of materials by chemical interaction with their environment. The most common source of corrosion in boiler is dissolved gases i.e. oxygen, carbon dioxide, etc. Of all these gases oxygen is most aggressive.
If the pH has significantly dropped below 8.5 then a phenomenon called "water side thinning" may occur. Water side thinning means thinning of water side walls due to acidic attack. This attack is mainly in the stress regions of boiler i.e maximum thinning occurs along the side of the tube towards flame.
Magnetite
Acidic Attack
Caustic Attack
(a) is a natural protective film formed on boiler surfaces as it resists the influence of water and contaminants to further react with steel material.
Iron compounds exists in the condensate system or when the boiler is out of service
(a)
Types of Amines in practise which form a protective film in the metal
(a)
Carryover simply means (a) .
What are the two principle factors which contribute to Carryover?
(a)
There is a limit on maximum amount of salinity which a boiler water can sustain. If this value exceeds than normal then there is a risk of formation of larger bubbles. Larger the bubbles produced greater the turbulence on water surface and this causes (a) .
It distributes feed water from the downcomers to the headers and generating tubes. Provides a space for accumulating precipitates and allows them to be blown down.
(a)
Is a standard feature of a water-tube boiler. It is a reservoir of water/steam at the top end of the water tubes. The drum stores the steam generated in the water tubes and acts as a phase-separator for the steam/water mixture.
Boiler
Water Drum
Steam Drum
Headers
These have a similar purpose to the water drum but are smaller in size. Due to their reduced size they may have a square cross section without resorting to exceptional thickness.
Boiler
Water Drum
Steam Drum
Headers
Consists of a large number of small diameter tubes in the gas flow, more commonly found in boilers of an older design For roof fired boilers the generating bank may consist of one or two rows of close pitched tubes.
Generating tubes
Screen tubes
Waterwall tubes
Contains the heat of the heat of the furnace so reducing the refractory and insulation requirements.
Generating tubes
Screen tubes
Waterwall tubes
These are larger bore tubes receiving the radiant heat of the flame and the convective heat of the hot gasses. The large diameter keeps the steam/water ratio down hence preventing overheating. There main duty is to protect the superheater from the direct radiant heat. On a modern marine radiant heat boiler the screen wall is formed out of a membrane wall.
Generating tubes
Screen tubes
Waterwall tubes
Waterwall tubes comes in three designs except;
Water cooled with refractory covered studded tubes
Membrane Wall
Open pitched exposed tubes
This is like a back up valve to the main steam stop valve. This means that in case some problem occurs with the main steam stop valve, the auxiliary valve still protects the system from any kind of damage. It is also a non return valve type.
(a)
Used for emptying the boiler water, the blow down valve is fitted at the lowermost end of the boiler. It is also used for partial emptying the boiler and is an important valve in the blow down process.
Pressure Gauge Connection
Sampling Connection
Air release Cock
Blow Down Valve
An important equipment for the boiler starting procedure, the air release cock are fitted in boiler drums, headers etc to purge out the air when filling the boiler or during raising steam.
Pressure Gauge Connection
Sampling Connection
Air release Cock
Blow Down Valve
This connection is mainly for taking feed water samples for testing and analysis purposes. The samples are collected through this connection and if any kind of chemicals that are to be added to the boiler water they are injected through the this connection.
(a)
__________ are fitted on the boiler drums and superheaters for pressure readings. They should be periodically checked to prevent accidents due to wrong readings.
Pressure Gauge Connection
Sampling Connection
Air release Cock
Blow Down Valve
Water tube boilers use less water and produce more steam in comparison to it. Due to this reason the chances of accidents due to high temperature and pressure are greater. Due to this reason, water tube boilers have extra mountings.
Whistle Stop valve
Scum Valve
Automatic feed water regulator
Additional mountings on Water Tube boiler
It is small bore non return valve which is used to supply steam to the whistle straight from the boiler drum.
Whistle Stop valve
Scum Valve
Automatic feed water regulator
Additional mountings on Water Tube boiler
This valve is used for removal of impurities from the boiler water. The scum or impurities float on the top of the water. A shallow dish is positioned at the normal water level to collect the scum from the top of the water level.
(a)
Generally used during the boiler maintenance procedure
Sootblowers
High alarm level
Super heater circulating valves
Produces an alarm sounding when the boiler reaches high water level condition.
Sootblowers
High alarm level
Super heater circulating valves
Used during the initial warming up process and during the boiler starting procedure, the valves ensures a steady flow of steam and also act as air vents.
(a)
Oil fuel at a pressure of not less than 8 bar is supplied to the tangentially arranged ports, wherein it falls in pressure, resulting in the oil swirling around at high velocity inside the chamber. The greater the pressure drop the greater would be the velocity, but generally supply oil pressure would not be greater than 25 bar, high pressures create pumping and sealing problems.
(a)
With this type of atomizer throughput is varied by adjusting the amount of spill, i.e. the return flow from the burner.
(a)
With the differential pressure between delivery and spill kept constant the pressure drop across the tangential ports is kept constant and the rotational velocity of the fuel in the swirl chamber will not alter.
(a)
As the oil supply pressure is increased the spring loaded plunger moves to uncover extra tangential oil entry holes. The pressure drop and hence the rotational velocity of the oil remains nearly constant.
(a)
It consists of a motor driven fan, metering pump and fuel cup.
(a)
The fuel can be defined technically as any material that can burn. While commercially, the fuel can be called as any material that has specific calorific value and is able to react with oxygen in air to produce heat
(a)
Give the three types of boiler fuel.
(a)
(a) is used for generating steam are usually burned directly in the furnace
boiler, although the heat for the steam boiler may also be in the form of residual heat from another process.
(a) can be defined as rapid chemical combination of oxygen with combustible elements of fuel.
What are the two types of combustion?
Higher Heating Value (HHV)
Medium Heating Value (MHV)
Lower Heating Value (LHV)
Slow Heating Value (SHV)
The following are the aspects of water tube boiler EXCEPT:
Gas flow : lower than 50.000 pounds/hour
Temperature of gas inlet : small to adiabatic firing
Pressure of gas : commonly under 2 psig
Water inventory : low
The following are the aspects of fire tube boiler EXCEPT:
Gas flow : higher than 50.000 pounds/hour
Temperature of gas inlet : small to adiabatic firing
Pressure of gas : commonly high up to 2100 psig
Water inventory : lhigh
(a) are produced as soon as gas fuel or the volatiles in the coal, liquid fuel which form droplets, solid fuel which form small particles are put together with air, after that they are ignited.
A (a) is composed of 2 basic systems. One basic boiler system is the water-steam system which is known as boiler waterside. In waterside of boiler, water is heated and released by movement via water tubes, then water is transformed to steam, and also it retains as steam in the system.
List down the classification of steam boiler based on fuel.
(a)
(a) is a boiler which uses oil as its fuel to perform combustion process. It consists of several important parts such as burner nozzles, air compressor, atomizing air system, oil piping, oil metering valve system, flame ignition and the others.
(a) is a boiler which uses gas as its fuel. It consists of some important components such as flame ignition, gas metering system, air compressor, air piping, gas piping, burner nozzles, and the others.
It is one of important equipment to maximize steam boiler efficiency. Efficiency of boiler is influenced mostly by heat transfer process. One among the most necessary operations to increase heat transfer process is clean metal surfaces for absorb heat.
(a)
This type of soot blower is located in area superheater and reheater. There is not temperature limitation in its use. Has a pair (2) of nozzle in lance tube located on both side in exact opposition (angle 0o and 180o) with diameter approximately 22 or 25 mm. The steam flow through soot blower is approximately 4 to 20 tph.
(a)
This type of soot blower is located in area furnace. There is not temperature limitation in its use. Has 1 or 2 nozzle in lance tube with diameter approximately 25 mm. The steam flow through soot blower is approximately 3.5 tph. Mostly used in high temperature furnace of Pulverized Fuel Boiler. One soot blower is required to blow furnace area in every 10 m2.
Wall / Short Retractable Soot Blower
Rotary Soot Blower
Long Retractable Soot Blower
Rake Soot Blower
This type of soot blower is located in area boiler bank, economizer, and air heater. Its use is limited to temperature 1100o C. Have many nozzles in lance tube with diameter approximately 8 mm. The steam flow through soot blower is approximately 3.5 tph. Maximum lance length is limited until 7 m, if the steam boiler larger than 7 m, so soot blower will be installed in both sides and can be operated by motor or manual.
(a)
This type of soot blower is located in area fin tube economizer and vertical tubular air heater. Its use is limited to temperature 530o C. Have many sets of nozzle. The steam flow through soot blower is approximately 3.5 – 4.5 tph. Dimension of rake soot blower is limited to 5 m length and 3 m width.
(a)
The (a) is definitely one of heat exchanger applications. Flue gas simply leaves steam boiler and passes via air preheater. The combustion
air is passed through this equipment too to increase its temperature before being combined with boiler fuel.
(a) is the heat exchanger equipment to increase boiler efficiency by absorbing heat recovery of flue gases. The lower temperature of flue gas out from stack, the heat loss will be less and the fuel which is needed to convert water into steam will be also less in certain circumstances.
Name the three commonly classified Pressure gage.
(a)
Type pressure gage which has bourdon tube, it s an oval cross section of hollow tube. The tube has two ends, open and close. Open end is connected to fluids either water or steam and close end is connected to mechanical linkage in gage pointer.
(a)
This type of gage is commonly applied for the pressure under 30 psi.
(a)
(a) is a process of removing unwanted dissolved solids in boiler water. Dissolved solids in boiler water will be left behind during the evaporation process to generate steam.
(a) has function to control content level of impurities in boiler water.
(a) is discharge process of dissolved solid in boiler water continuously. Therefore, make-up water should be added in the feedwater system continually to compensate amount of discharged boiler water because of this process to maintain the water balance of a steam boiler.
(a) is the removal process of dissolved
Solid, silica, and other unwanted particles that carried out intermittently.
Boiler system consists of:
(a)
(a) is defined as water capacity to neutralize acid, or the quantity of anions in water which can neutralize hydrogen cations.
_________ is not soluble either in water or in acid and is usually in the form of colloids.
Quartz
Silica
Analcite
Aluminum
Name the two deposit of silica in boiler water.
(a)
The most commonly treatment that is used to produce water that contains very little silica is (a) .
Butterfly valve is valve which is used for regulate and isolate flow, it allow for slow stop flow.
True
False
Ball valve has similar function with butterfly valve, the differences is ball valve use spherical disc to regulate flow.
True
False
Safety valve is used for protect steam boiler if operating pressure exceed maximum allowable working pressure, the valve will automatically pop up to release excess pressure.
True
False
Control valve is non-automatic control to regulate how many percent debit flow of fluid will be allowed.
True
False
The boiler is supported at the water drum and the water wall lower headers, and there are no rigid connections at any other points in order to allow for thermal expansion.
True
False
