Steam nozzles are great for removing moisture as well as oil from steel surfaces. High velocity steam jets from nozzles impinge on the blades mounted on a wheel rotor get deflected by an angle and suffer a. Why is a nozzle used only impulse turbines, and not in. Rankine cycle, steam generators and their accessories, performance of boilers and combustion of fuel, high pressure boilers, flow through steam and gas nozzles, different type of steam turbines for power generation and. Steam boilers, engines, nozzles and turbines interview questions and answers pdf. The flow of steam through nozzles may be takenas adiabatic expansion. Steam turbine governing and its mechanism ece tutorials. Mix play all mix steam and gas power systems youtube lec 47. Calculate base dimensions of the nozzle and state of water steam at the exit. Assume friction loss in the nozzle is equal to 10% of the total enthalpy drop. If steam at high pressure is allowed to expand through a stationary nozzle, the result will be a drop in the steam pressure and an increase in steam velocity. When the speed of the engine is controlled by means of a valve in a steam pipe, which regulates the pressure of steam entering the engine, then the governing is known as a throttle governing b cutoff governing c bypass governing d none of these.
The flow of steam through nozzles may be regarded as adiabatic expansion. The particular nozzles tested, of convergentdivergent form, had a straightsided divergent portion of. The transition characteristics of the jets also depend on the nozzle cross sectional shape. Recent failures with flow nozzles are associated with using a stainless nozzle inside a p91 pipe. Find the properties of the steam at the stagnation state. Construction of steam nozzle if great pressure differences exist in front and at the back of inlet nozzles of steam turbines a secure attachment of the nozzles is sometimes rather difficult. The high pressure steam from the boiler expands while flowing through the convergent divergent nozzle. Impulse and reaction stage, degree of reaction, velocity triangle. The mass flow rate of water steam must be 0,3 kgs1. The effects of different nozzle structures on the performance of a steam ejector have been investigated numerically with the computational fluid dynamics cfd technique. Flow of gases and steam through nozzles example, the required pressure in the combustion chamber of the space shuttle ssme engine was 20. Numerical study on condensation process of steam flow in. The variation of steam pressure in the nozzle depends upon the velocity, specific volume and dryness fraction of steam. Oxidizer and fuel pumps are powered by combustion turbines that use fuel and engine oxidant as fuel or have other fuel 16, s.
This course provides a simple understanding of the steam and gas power systems. The critical pressure ratio for initially dry saturated steam is a. In the impulse steam turbine, the overall transformation of heat into mechanical work is accomplished in two distinct steps. Features removal of moisture and oil from steel surfaces. Impulse and reaction stage, degree of reaction, velocity triangle, week 6. By following one or more of the steps from a to d given above and steps e and f given below, such nozzle loads can be reduced. The nozzles are designed for lowest operating pressure ratio between nozzle throat and exit. In this nozzle the cross sectional area gradually decreases from the entrance area to the minimum area which is the exit. Nozzle governing of steam turbine with inner architecture for example if the turbine consists of 10 nozzles for full power100 %. Basic principles of classical and statistical thermodynamics pdf 35p this note covers the following topics. Sep 06, 2015 steam nozzle properties of steam can be obtained from tables or from hs chart. The difficulties are eliminated by milling or otherwise machining the nozzles into a. The steam jet pump is basically comprised of an expanding motive steam nozzle producing high supersonic velocities, a combining chamber for bringing the suction fluid into contiguous or mating contact with the highvelocity motive steam, and a diffuser for compressing both the suction and motive fluids up to the.
Pipe flow measurement flow nozzles iso 51673, bs 10421. Steam issuing out from the nozzles meets the leading edges of the blades and energy may be lost if the entry is not smooth enough and eddies are formed. Numerical investigation on the mixing process in a steam. Pdf power plant lecture notes chapter4 steam turbine. Numerical solution of steam flow in a nozzle using different. The single nozzle, fixed orifice is the simplest type of ejector. For 16 kgs of steam mass flow rate determine heat drop in nozzle and final state of steam leaving nozzle assuming heat loss to surroundings as 10 kjkg.
The steam possessesa very high velocity at the end of the expansion, and the enthalpy decreases as. Vortex tube refrigeration it consists of nozzle, diaphragm, valve, hotair side, coldair side. How to calculate the steam flow through each nozzle. Pdf power plant lecture notes chapter2 steam power. In a spindleoperated ejector, the nozzle and tapered spindle work together similar to a needle valve. Steam nozzle steam nozzle objective type questions and. The expansion causes a very low pressure and increases steam velocity. Friction exists between the steam and the sides of the nozzle. There is a reason why nozzles are not required for reaction turbines. Operating a steam jet vacuum system at steam pressures lower than those specified in the system design will reduce system stability. A suitable test technique using a closedjet tunnel is demonstrated. How to determine the steam flow in the nozzles of the stage. The steam should be dry and saturated, unless the system specifi. Steam boilers, engines, nozzles and turbines, mechanical engineering multiple choice questions objective type questions, mcqs, with question and answers, download free pdf, mechanical engineering, multiple choice questions, objective type questions, mechanical engineering short notes, rapid fire notes, best theory.
The former is a function of x 1 while the later x0. Steam nozzle steam nozzle objective type questions and answers. The available energy of steam is first changed into kinetic energy, and this kinetic energy is then transformed into mechanical work. And then the later part of the nozzle, in which the steam derives more in volume than in velocity. Reaction turbine 2 iii steam turbine operating range 2 3. In the step of admission of steam turbines reation there are several nozzles that distribute the steam to the blades. Mechanical power engineering department faculty of engineering. The inlet narrows to form a throat, which is followed by an enlarging form so that atmospheric pressure is reached by adiabatic expansion, producing a flat jet pattern. When whole mass of steam is converted into steam then it is called as dry steam. During the first part of the nozzle, the steam increases its velocity. Steam boilers engines nozzles and turbines mechanical. Lecture series on steam and gas power systems by prof.
The course contains the analysis of vapour power cycle i. This is the heart of an ejector since it converts the energy of pressure to velocity and directs the flow of motive steam into the diffuser. Vanita thakkar bit 17 nozzles a nozzle is a device, a duct of smoothly varying cs area, that increases the velocity of a fluid at the expense of pressure. The project on development of remaining three quadrants to nptel phasei under grant in aid nmeict, mhrd, new delhi. Steam ejector is an important component in engineering applications, which require high. In todays article, you are gonna get a brief knowledge on boiler accessories and mountings. Pp ea for less e, e t a pp a a, could derive more forward push by. Steam nozzles and turbines mechanical engineering questions. They usually save as much as 10% to 20% in motive steam, compared with single nozzle units designed for the same conditions. Types, combustion in boilers, performances evaluation, analysis of losses, feed water treatment, blow down, energy conservation opportunities.
Twodimensional kinetics tdk computer program, which has been combined with a boundary layer module blm, is the industry standard jannaf joint. The chief use of nozzle is to produce a jet of steam or gas of high velocity to produce thrust for the propulsion of rocket motors and jet engines and to drive steam or gas turbines. Boilers bureau of energy efficiency 27 syllabus boilers. The stress concentration will also vary due to the size of hole, location of hole and shape of hole.
Both the conventional conventional bell and unconventional aerospike and expansiondeflection nozzles can be the subject of consideration of the moc. Exhaust steam conditions, extraction and admission 7 6. Isokinetic sampling nozzles probes for sampling gases and liquids including steam and water in steam plants. For the love of physics walter lewin may 16, 2011 duration.
Here the distance between plate and nozzle is constantly increasing by u ms. We assume that steam follows an isentropic law pvk k isentropic index for steam for dry saturated steam k 1. Steam table lecture 7 ideal gas laws, different processes lecture 8 introduction to vapour power cycle lecture 9 vapour power cycle lecture 10 steam power cycle, steam nozzle lecture 11 basic concept of turbine, velocity diagram lecture 12 steam turbineimpulse. Due to number of openings for either inlet or outlet, stress concentration is more on the structure. If the load demand has reduced to 60 % then out of 10 nozzles, 4 nozzles can be closed to provide 60% load with out delay. When the dry steam is further heated at constant pressure, the temperature increases the above saturation temperature. It does not cover the use of nozzles and venturi nozzles in pipe sizes less than 50 mm or more than 630 mm, or for pipe reynolds numbers below 0.
Power plant lecture notes chapter2 steam power plant cycles. This is known as critical pressure ratio and different for different fluids. The maximum gas flow through a nozzle is determined by critical pressure. Mar 07, 2015 vanita thakkar bit 16 energy conversion in steam turbine energy conversion in steam turbine takes place in two steps. Bellshape nozzles or parabolic nozzles, which are as efficiency as the simplest conical nozzle, but shorter and lighter, though more expensive to manufacture. The steamhas a very high velocity at the end of the expansion, and the enthalpy decreases as expansion takes place. The steam has a very high velocity at the end of the expansion, and the enthalpy decreases as expansion takes place. Steam generator, turbine, pump, nozzle, throttling, the mathematical expression of the 1st law for a closed system, examples of.
Boiler mountings and accessories details with video lecture. In order of increasing capacity, three boiler types are the firetube, watertube and waterwall boilers. Halama and hric 3 studied numerical solution of two phase steam flow in the. The nozzles are of converging or diverging or convergingdiverging type as per the design. The main use of steam nozzle in steam turbines is to produce a jet of steam with a high velocity. The steam passes through the stationary nozzles and is directed at high velocity againstthe rotor buckets causing the rotor to rotate at high speed.
Property relationships for pure substances and mixtures, thermodynamic relations, ideal gas mixtures, combustion thermodynamics, gas power cycles, vapour power cycles, refrigeration cycles, reciprocating compressors, compressible flows and steam nozzles. Nozzle exhaust port intake port connecting deflector transfor port piston exhaust gases exhaust. Power cycles otto cycle spark ignition diesel cycle brayton cycle gas turbine rankinecycle. Ideal for saturated steam, superheated steam, and water sampling. Steam encounters these losses in the blade passages, which depends on the roughness of the blade surface. For hp main steam pipes, a flow nozzle is not strictly needed you can use a short radius elbow with an elbow tap as indicative of steam flow rate, after it is calibrated. Thermodynamic and nonthermodynamic properties, microstates and thermodynamic states, concept of energy, microstate driving forces, thermodynamic driving forces, intensive and extensive propertie, the laws of thermodynamics, heat and thermal energy, entropy, energy transport by. An efficient nozzle is designed to have higher velocity, greater mass flow and minimum inlet losses. A boiler is a closed vessel in which water is heated, vaporized and converted into steam at a pressure higher than the atmospheric pressure. The steam which contains some water particles in superposition. It is not possible to increase the flow by increasing inlet pressure.
Critical flow nozzles are also called sonic chokes. The far field mean centreline velocity function of a round jet and plane jet are different. A single moving plate is, therefore, not a practical case. Dry saturated steam is expanded in a nozzle from 1. In this paper by changing the angle of the nozzles, the efficiency of the turbine calculated in terms of nozzle angle. Frequently more compact designs and savings in cost can result from such designs. The steam attains very high velocities in the range of ms to 50 ms. Steam nozzles nozzle statistical mechanics free 30day. The focus here will be on boilers sized in between these two extremes, which is also where there is the greatest diversity of design. Flow is attained at maximum value corresponding to critical exit pressure c. To decide if you need the blank or flat nozzle you need to analyze the job its for. Material brass kbs type spray angle model number inlet connection minimum orifice diameter mm model flow rate of saturated. A source of dry steam at or slightly above design pressures must be available at the ejector nozzles at all times.
But in order to find the critical pressure ratio critical velocity maximum mass flow rate, approximate formulae may be used. Numerical study on condensation process of steam flow in nozzles. The performance of the steam ejectors with five different nozzle structures, namely, conical, elliptical, square, rectangular and crossshaped nozzles, have been compared. The smallest section of the nozzle is called throat. Nptel video course ocean engineering advanced marine structures. Pressure and temperature of the water steam is 80 bar respectively 500 c at input to the nozzle. Fixed restriction variable head type flow meters using different sensors like orifice plate, venturi tube, flow nozzle, pitot tube, dall tube, quantity meters like positive displacement meters, mass flow meters etc. Nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. The heat energy required for steam generation is produced by burning fuel in the furnace. Other applications include oil in water, water in oil, propant in oil, and sand in oil. It is not applicable to the measurement of pulsating flow. Steam nozzles ppt steam nozzles a nozzle is a duct of.
Lec10 steam power cycle, steam nozzle lecture series on applied thermodynamics for marine systems by prof. By steady flow energy equation between sections 1 and 2. Vtunptelnmeict project progress report the project on. Natural water circulation, by convection in water tube boilers, with increase in pressure of boiler. Applied thermodynamics videos, lectures, classes, courses, books, tutorials nptel thermodynamics videos, thermodynamics video lectures, thermodynamics video classes. The difference between cornish boiler and lancashire boiler is that a former is fire tube type and latter is water tube type boiler. Steam nozzle steam nozzle nozzles for special purposes applications speciallydesigned orifice saves and reduces steam for the same effect. The water and steam run through a continuous cycl e of water boiled into steam, used in the engine, condensed back to water, and then pumped back into the boiler for reuse, a cycle first studied scientifically by the. Pdf preliminary design of an axial turbine stage for a. High pressure, high temperature steam expands in nozzles and comes out at a high velocity. Depending on the condition of the steam either the curve for saturated. Steam nozzles and engines mechanical engineering questions.
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