What is a closed feedwater heater?
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What is a closed feedwater heater?
Closed feedwater heaters are typically shell and tube heat exchangers where the feedwater passes throughout the tubes and is heated by turbine extraction steam. These do not require separate pumps before and after the heater to boost the feedwater to the pressure of the extracted steam as with an open heater.
What is TTD in a feedwater heater?
Terminal Temperature Difference (TTD) provides feedback on the feedwater heater’s performance relative to heat transfer and is defined as the saturation temperature of the extraction steam minus the feedwater outlet temperature. An increase in TTD indicates a reduction in heat transfer while a decrease an improvement.
What are the types of feedwater heaters?
Three types of Feedwater Heaters
- Low Pressure Heater (LP): A Feedwater Heater located, with regard to feedwater flow, between the condensate pump and either the boiler feed pump or, if present, an intermediate pressure (booster) pump.
- High Pressure Heater (HP):
- Intermediate Pressure Heater (IP):
What is a low pressure feedwater heater?
Low pressure (LP) feedwater heaters are basically simple straightforward ‘tube and shell’ heat exchangers, with the condensate passing through the tubes and the bled-steam being admitted to the shell.
What is the effect of TTD in heater size and cycle efficiency?
An increase in TTD indicates a reduction in heat transfer, while a decrease indicates an improvement. Typical ranges for TTD on a high-pressure heater with and without a desuperheating zone are -3° F to -5° F and 0° F, respectively. The TTD for low-pressure heaters is typically around 5° F.
What is GSC in turbine?
GSC (Gland steam condenser) is simply an efficiency improver in thermal power plants. The working of GSC is quite simple as like condenser. It has shell inside which some tubes are mounted.
Is pressure constant through a closed feedwater heater?
In an ideal closed feedwater heater, the feedwater is heated to the exit temperature of the extracted steam, which ideally leaves the heater as a saturated liquid at the extraction pressure….
| Open Feedwater Heaters | Closed Feedwater Heaters |
|---|---|
| Good heat transfer characteristics | Less effective in heat transfer |
What is TTD in condenser?
While TR is an indication of the amount of heat absorbed by the circulating water, TTD is a measure of the efficiency with which heat is transferred from the shell side of the tube to the water side. A lower TTD is always better, and all condensers are designed with a specific design TTD.
Which of the following is true for an open feedwater heater?
Which of the following is true for an open heater? Explanation: The open heater has high heat transfer capacity. 7.
What is Seal steam?
The seal steam system enables the turbine to be sealed where the shaft exits the casing—in effect keeping “air out and steam in.” Sets of labyrinth packing are used along the turbine rotor where the rotor exits the turbine casing to maintain this pressure differential between the inside and outside.
What is usual pressure of gland sealing steam?
Steam with a pressure of 0.2 or 0.3 kg/cm2 is provided with a pressure control valve. Temperature remains upto 200. Since in consensing turbine vacuum is maintained and hence to maintain that vacuum sealing steam is provided at gland (both HP and LP).
How do feedwater heaters increase efficiency?
By increasing the feed water temperature, the feed water heater increases the overall efficiency of the steam power plant. Feed water heater increases the feed water temperature near to the boiling point. So, the interning water of the boiler can easily transfer into steam and improve the efficiency of the plant.
What is boiler feedwater temperature?
between 185 and 195°F
Most feedwater tanks are equipped with a steam sparger, which heats the tank with steam from the boiler. The temperature of the feedwater tank should be maintained between 185 and 195°F (85 and 90°C) to reduce the amount of oxygen in the water.
What is condenser cleanliness factor?
As mentioned above, condensers are typically designed with an 85% cleanliness factor that allows for some fouling. As the condenser begins fouling and uses the extra area, the condenser performance is affected. The tube velocity will increase if the same cooling water flowrate is used.
What is labyrinth packing?
The labyrinth packing for high-temperature parts consists of an alloy steel labyrinth body inserted with Cr-Mo steel strips, which for low-temperature parts consists of a labyrinth body and strips integrally formed of nickel silver or phosphor bronze stock.
Why there is a requirement of gland sealing system?
The turbine gland sealing system (TGSS) prevents the escape of steam from the turbine shaft and casing penetrations and the glands of main steam stop and control valves. This system also prevents air leakage into the low pressure turbine glands.
