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Although several factors influence the formation of deposits on turbine components, the general effect is the same no matter what the cause. Adherent deposits form in the steam passage, distorting the original shape of turbine nozzles and blades. These deposits, often rough or uneven at the surface, increase resistance to the flow of steam. Distortion of steam passages alters steam velocities and pressure drops, reducing the capacity and efficiency of the turbine. Where conditions are severe, deposits can cause excessive rotor thrust. Uneven deposition can unbalance the turbine rotor, causing vibration problems.
The nature of silica deposits found on turbine blades varies greatly. lists a number of silica compounds that have been identified in various studies of turbine blade deposition. Of these, amorphous silica (SiO2) is the most prevalent.
Localized Silica Saturation. Turbine deposits are also formed where localized silica saturation occurs and silica condenses from the steam in those areas of the turbine. Partial evaporation of the precipitated silica can then occur with only a portion of the silica being dissolved by the continuous steam flow. Deposits remain as a result.
Turbine Velocity. Another factor affecting the location of turbine deposits is the velocity in the turbine. Steam flows from the inlet to the outlet of the turbine in only a fraction of a second. Consequently, deposition is shifted downstream from the saturation point by the high steam velocities.
Prevention of Silica Deposits
The most significant factor in minimizing turbine silica deposits is the maintenance of low silica concentrations in the boiler water. External treatment equipment must be operated carefully to limit the amount of silica entering with the makeup water, and the condensate must be monitored to minimize contamination. After silica enters the boiler water, the usual corrective action is to increase boiler blowdown (to decrease the boiler water silica to acceptable levels) and then to correct the condition that caused the silica contamination.
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What are the reasons of Erosion and deposits in steam turbine?
The steam. Steam passing through a turbine spinning at a speed of 3600rpm will have a tip velocity on it largest wheel of about 1800 feet per second. In order to reach that speed the steam must be moving at least that fast through the blades. that is about 1200 miles per hour, or more than 1 1/2 times the speed of sound. The steam also over time picks up impurities from the steam pipe to the turbine, these will cause erosion similar to sand blasting. The water in the boiler has impurities that can't be removed effectively, one is silica. At high temperature in the boiler the silica vaporizes into the steam passages, as it passes through the turbine the steam cools and the silica solidifies again into deposits on the turbine blades. There are other causes but these are the most common.
What is a steam turbine?
It is an engine.A steam turbine is a heat engine that uses the expansion of steam passing through stationary nozzles and blades on a shaft to turn the shaft. The steam can move through the turbine axially (one end of shaft to the other end), radially (shaft to outer casing), or tangentially (around the outer edges of the turbine wheel). In an impulse turbine, the steam is expanded in nozzles and pushes the blades. In a reaction turbine the steam is expanded in the nozzles AND in the blades, the reaction of the expansion of the steam pushes away from the blades spinning the wheel in the process. The expansion of the steam is necessary to increase its velocity through the turbine.
What are the parts of steam turbine?
Steam turbine is a machine that extracts thermal energy from pressurized steam. It is made up of casing essential to which the blades are attached onto it and a rotor that carries the moving blades.
High pressure steam turns the blades of?
High pressure steam hits the blades of a TURBINE and turns its shaft.
What do you understand by property of a system?
The property of steam is the precipitants ingress through the water in to the steam cycle The steam conductivity and silica contents so called property of steam. there fore the boiler drum chlorides(cause of higher conductivity in the Super heated steam) and water PH has to be controlled to get pure Super heated Steam from boiler drum risers. Silica can cause of turbine blades erosion. Higher Conductivity cause of Chlorides which can cause of Corrosion on turbine blades. PH controlled to avoid acid attack and pitting and scales deposition.
What is tenon in steam turbine?
It is what attaches the shroud to the turbine blades
Which type of steam is imparted on the blades of turbine?
Superheated steam.
A boiling water nuclear reactor delivers what to the turbine blades?
A boiling water nuclear reactor delivers steam to the turbine blades. The heated water in the reactor boils and produces steam, which is then used to drive the turbine blades and generate electricity.
What are the reasons of Erosion and deposits in steam turbine?
The steam. Steam passing through a turbine spinning at a speed of 3600rpm will have a tip velocity on it largest wheel of about 1800 feet per second. In order to reach that speed the steam must be moving at least that fast through the blades. that is about 1200 miles per hour, or more than 1 1/2 times the speed of sound. The steam also over time picks up impurities from the steam pipe to the turbine, these will cause erosion similar to sand blasting. The water in the boiler has impurities that can't be removed effectively, one is silica. At high temperature in the boiler the silica vaporizes into the steam passages, as it passes through the turbine the steam cools and the silica solidifies again into deposits on the turbine blades. There are other causes but these are the most common.
What is a steam turbine diaphragm?
Steam turbine is comprising of stages, number and size of the stages depands upon the break horse power of the turbine. The stage has set of moving and fixed blades. The moving blades are attached to the rotor while the stationary blades is called Diaphragm. The diaphragm guides the steam to glide over the moving blades for producing rotary motion.
How does steam turbine works?
Steam or water, it works the reverse of a fan, where the fan pushes air down, the turbine is turned by the steam or water. there's a shaft leading from the turbine to the generator, which produces the electricity
What is a steam turbine?
It is an engine.A steam turbine is a heat engine that uses the expansion of steam passing through stationary nozzles and blades on a shaft to turn the shaft. The steam can move through the turbine axially (one end of shaft to the other end), radially (shaft to outer casing), or tangentially (around the outer edges of the turbine wheel). In an impulse turbine, the steam is expanded in nozzles and pushes the blades. In a reaction turbine the steam is expanded in the nozzles AND in the blades, the reaction of the expansion of the steam pushes away from the blades spinning the wheel in the process. The expansion of the steam is necessary to increase its velocity through the turbine.
What are the parts of steam turbine?
Steam turbine is a machine that extracts thermal energy from pressurized steam. It is made up of casing essential to which the blades are attached onto it and a rotor that carries the moving blades.
High pressure steam turns the blades of?
High pressure steam hits the blades of a TURBINE and turns its shaft.
What shrouding installed on the blading of a steam turbine serves?
Shrouding serves toconfine steam to the passage of the turbine blades. It also helps to stiffen the blades against vibration.
What do you understand by property of a system?
The property of steam is the precipitants ingress through the water in to the steam cycle The steam conductivity and silica contents so called property of steam. there fore the boiler drum chlorides(cause of higher conductivity in the Super heated steam) and water PH has to be controlled to get pure Super heated Steam from boiler drum risers. Silica can cause of turbine blades erosion. Higher Conductivity cause of Chlorides which can cause of Corrosion on turbine blades. PH controlled to avoid acid attack and pitting and scales deposition.
What is positive axial displacement of steam turbine?
axial shift of a steam turbine is the shifting of turbine rotor in the forward and backward direction due to steam thrust on blades of rotor.
