What is Condenser ?
The primary purpose of the condenser is to condense the exhaust steam from the turbine as well as thus recover the high-quality feedwater for reuse inwards the cycle.
In guild for a steam ability station to operate an efficient-closed cycle, the condensing plant, cooling H2O (CW) system, as well as associated pumps must extract the maximum quantity of rut from the exhaust steam of the LP turbines
The primary functions of the Condensing flora are:
· To render the lowest economical rut rejection temperature for the steam bike
· To convert the exhaust steam to H2O for reuse inwards feed the bike
· To collect the useful residual rut from the drains of the turbine feedheating plant, as well as other auxiliaries.
· In so doing, the circulating cooling H2O temperature beingness depression enough, it creates a depression dorsum clit per unit of measurement area (vacuum) for the turbine to exhaust to.
· This clit per unit of measurement area is equal to the saturation clit per unit of measurement area corresponds to the condensing temperature which is a component subdivision of the cooling H2O temperature.
· Since the enthalpy driblet as well as hence turbine work, per unit of measurement clit per unit of measurement area driblet is much greater at depression clit per unit of measurement area than the high clit per unit of measurement area terminate of the turbine.
· The condenser, yesteryear lowering the dorsum clit per unit of measurement area a picayune flake increases the piece of job of the turbine, increases the flora efficiency, as well as cut down steam time period for a given output
· The lower the pressure, the greater the effects
Condensing ability plants are, therefore, much to a greater extent than efficient than non-condensing ones.
(Why Condensing ability plants are much to a greater extent than efficient than non-condensing ones, I intend you lot got the answer)
Some other functions of Condenser: Additional Condenser Objectives
In add-on to the condenser satisfying the primary functions, its pattern must likewise live on capable of coming together the next objectives: · To render the turbine amongst the most economical dorsum clit per unit of measurement area consistent amongst the seasonal variations inwards CW temperature or the rut sink temperature of the CW system.
· To effectively forbid chemic contamination of the condensate either from CW leakage or from inadequate steam infinite gas removal as well as condensate de-aeration.
· The aim of the designs is to ensure that these objectives are met within the framework of the next practical considerations:
i. Economies of size, infinite as well as pumping ability ii. Ease of maintenance as well as structure iii. An economical turbine dorsum clit per unit of measurement area is from 1.0 to 3.5 inwards Hg abs Classification of Condensers:
• There are 2 wide classes of condensers: Direct contact type condensers — the condensate as well as CW straight mix as well as come upwards out equally a unmarried current
Surface condensers — are shell-and-tube type Heat Exchanger where the 2 fluids hit non come upwards inwards direct contact as well as the rut released yesteryear the condensation of steam is transferred through the walls of the tubes into the cooling H2O continuously circulating within them.
Direct Contact type condenser
When depression investment is desired as well as condensate recovery is non a factor, direct-contact condensers are effective. They are relatively uncomplicated to build as well as operate, are express to sizes less than 250,000 lb. (114 tons) of steam per sixty minutes Direct Contact type condensers tin mail away live on of 3 types:
· Spray condenser
· Barometric condenser
· Jet condenser
Direct Contact Spray Type
· In a spray condenser the cooling H2O is sprayed into the steam which yesteryear mixing straight amongst mutual frigidness H2O gets condensed.
· Part of the condensate, equal to the turbine exhaust flow, is sent dorsum to the flora equally feedwater.
· The balance is cooled inwards a dry out cooling tower to soil five as well as is as well as so sprayed on to the turbine exhaust thus, the cooling H2O continually circulates.
Direct Contact Barometer Type
· The cooling H2O is made to autumn inwards a serial of baffles to expose large surface expanse for the steam fed from below to come upwards inwards direct contact.
· The condensed steam as well as the cooling H2O mixture falls inwards a tail pipage to the hot good below the tail pipage compresses the mixture to atmospheric clit per unit of measurement area at the hot good yesteryear virtue of its static head
Direct Contact Jet Type
· In the jet-type Condenser the acme of the tail pipage is reduced yesteryear replacing it amongst a diffuser
· The diffuser helps raising the clit per unit of measurement area inwards a curt distance than a tail pipe
· In all direct contact Condensers the non-condensable gases must live on removed which is commonly done amongst a steam-jet air ejector (SJAE)
Surface Type Condensers
· Surface Condensers trounce as well as subway scheme rut exchangers are generally used inwards ability plants
· For the convenience of cleaning as well as maintenance cooling H2O flows through the tubes as well as steam condenses exterior the tubes
· Present-day condensers receive got rut transfer surface areas that overstep 1 1000000 ft2 (93000 m2)
· Condensers are designed amongst one, two, or iv H2O passes.
· The disclose of passes determines the size as well as effectiveness of a Condenser.
Single Pass Condenser
In an Influenza A virus subtype H5N1 single-pass condenser cooling H2O flows through all the Condenser tubes once, from 1 terminate to the other. Two Pass Condenser
In Two-pass condenser H2O enters one-half the- tubes at 1 terminate of a divided inlet H2O box. And as well as so passes through these tubes to an undivided H2O box at the other end. Then they opposite direction as well as passes through the other one-half of the tubes dorsum to the other side of the divided H2O box. 
Single Pass Condenser should live on used or 2 pass? A single-pass condenser amongst the same full disclose size of tubes, i.e., the same heat-transfer area, as well as same H2O velocity, requires twice equally much H2O flows only results inwards one-half the H2O temperature ascent as well as thus lower condenser clit per unit of measurement area Thus such a single—pass condenser is proficient for flora thermal efficiency as well as reduces thermal pollution, only requires to a greater extent than than twice the H2O as well as hence iv times the pumping power Water boxes are ofttimes divided beyond the divisions required yesteryear the disclose of passes
A divided H2O box single-pass condenser may receive got a partition inwards both the inlet as well as outlet H2O boxes at opposite ends of the condenser — allows one-half the condenser to operate spell the other one-half is beingness cleaned or repaired.
Divided H2O boxes receive got duplicate inlet as well as outlet connections, each amongst its ain circulating H2O circuit. Many large modern-day ability plants commonly receive got 2 or to a greater extent than low-pressure turbine sections inwards tandem. The condenser may live on divided into Corresponding sections or shells.
Single Pressure Condenser
When the turbine exhaust clit per unit of measurement area inwards all sections is same, i.e. when the exhaust ducts are non isolated from each other, it is known equally a single-pressure condenser. Multi-Pressure Condenser
If the exhaust ducts are isolated from each other, these private condenser trounce pressures volition increment because the circulating H2O temperature volition increment equally it time period from trounce to trounce — a multi-pressure condenser Why multi clit per unit of measurement area condenser is preferable than unmarried clit per unit of measurement area condenser?
A multi-pressure condenser results inwards efficiency improvement because the average turbine dorsum clit per unit of measurement area is less compared amongst that of a single-pressure condenser (Which is determined yesteryear the highest circulating H2O temperature) In essence, condensers are almost custom designed to arrange private requirements of steam time period available cooling H2O time period as well as temperature, available infinite as well as other variables. Surface Type Condenser Design Considerations
A condenser pattern tin mail away live on established for a given surgical operation rating based on 8 principal variable which are · Total rut transferred, which is a component subdivision of
Ø Weight of steam to live on considered.
Ø Enthalpy of steam less enthalpy of condensate.
Ø Enthalpy loss or gains of drains as well as brand up.
· Absolute static steam pressure.
· Cooling H2O time period rate
· Cooling H2O inlet temperature.
· Cooling H2O outlet temperature.
· Cooling H2O velocity through tubes.
· Effective rut transfer surface, which is a component subdivision of:
Ø Number of tubes Tube length Tube diameter Tube thickness Tube cloth Number of cooling H2O passes
Ø Service conditions:
o Tube cleanliness
o Air in-leakage
The subway scheme cloth tin mail away be:
- Cupronickel (70% Cu, 30% Ni)
- Aluminum brass (76% Cu, 22% Zn. 2% AI
- Aluminum bronze (95% Cu, 5% AI)
- Muntz metallic (60% Cu, 40% Zn)
- Admiralty alloy (71 % Cu, 28% Zn, 1 % Sn)
- Stainless steel
De-aeration or Air Removal of condenser
Air may leak into the condenser trounce through flanges or sometimes comes along amongst steam which has leaked into the exhaust terminate of the turbine along the shaft This air affects the condenser surgical operation badly because of the next reasons: · It reduces the rut transfer considerably
· It reduces the condenser vacuum as well as increases the turbine exhaust clit per unit of measurement area thus reducing the turbine output
Good de-aeration within a condenser requires time, turbulence as well as proficient venting equipment · The mutual frigidness condensate falling from the lower tubes must receive got sufficient falling acme as well as scrubbing steam for reheat as well as de-aeration
· The scrubbing steam is provided yesteryear allowing around of the incoming steam to hap through an opened upwards time period expanse straight to the bottom tubes to reheat the condensate — non condensable are to a greater extent than easily released from a hotter than a colder liquid.
· Once the non-condensable are released, they are cooled to cut down their book earlier beingness pumped out of the condenser
· For this a disclose of H2O tubes, most half-dozen to 8% inwards the subway scheme bundle, are prepare aside for this function.
· This, called an air-cooler section, is baffled to separate the non condensables from the primary steam time period
· Most of the condensation takes house on the primary banking firm of tubes as well as the air is drawn over around other smaller banking firm which is shielded from the primary banking firm yesteryear a baffle as well as is called the a aircooler.
· Here, farther condensation takes house at a lower temperature as well as thus, in that place is saving inwards feedwater equally good equally inwards air ejection load.
· Jet pumps are used to view out the non-condesables — known equally steam jet air ejectors (SJAE)
Ø In a two-stage ejector, primary steam is used at a reduced clit per unit of measurement area that enters a driving nozzle inwards the starting fourth dimension phase ejector
Ø It exits amongst a high velocity as well as momentum as well as reduced clit per unit of measurement area
Ø This reduced clit per unit of measurement area draws inwards the non-condensables from the condenser
Ø By a procedure of momentum exchange, the gases are entrained yesteryear the steam jet
· The combined time period of steam as well as gas is instantly compressed inwards the diffuser of the first-stage ejector as well as discharged into a little inter-condenser, where the steam is condensed yesteryear passing across cooling pipes inwards much the same trend equally the primary condenser.
· Cooling here, however, is accomplished yesteryear the primary condenser condensate as well as is component subdivision of the feedwater heating system, resulting inwards improvement inwards efficiency of the plant.
· The non-condensables as well as whatsoever remaining steam are as well as so passed to the 2d phase ejector, where they are compressed farther as well as passed to an after-condenser
Vacuum efficiency of a Condenser
Sometimes a term called ‘Vacuum efficiency’ is ofttimes used a regard to a condenser It is defined as: Vacuum efficiency = (Vacuum produced yesteryear steam condenser inlet/Barometric clit per unit of measurement area - Saturation clit per unit of measurement area at exhaust steam pressure) Condenser efficiency
Another term called ‘condenser efficiency’ is likewise used sometimes. Which is defined as: Condenser efficiency = (Actual temperature ascent of cooling water/Maximum temperature ascent of cooling water) Read :