Key Parameters for Air Cooled Condenser Design

Site topography and features Site elevationSite meteorologyAnnual temperature duration curvesPrevailing wind speeds and directionsExtreme conditions (hottest day, freezing conditions)Topography and obstructionsNearby hills, valleys, etc.Nearby structures, coal piles, etc.Nearby heat sources, including auxiliary coolers, plant vents, etc.Other heat sources or interferences.Noise limitations at the ACC itself or at some specified distance, as set by neighboring communities or open space sanctuariesMaximum height restrictions“Footprint” constraints (length, width)Location restrictions, particularly distance from turbine exhaust Seismic loads, requirements, and zones

Project Specific Data Required for Air Cooled Condenser Design

Plant capacity: Exhaust steam flow: Exhaust steam enthalpy: Exhaust steam back pressure: Ambient temperature a. Minimum : b. Maximum : c. Design ambient temperature : Type of fin : Relative humidity a. Minimum: b. Maximum : c. Average : Plant location : Site elevation or Mean sea level : Wind speed : Seismic zone : Dump steam arrangement, if any : Plant layout : HMBD from steam turbine

Air Cooled Condenser Scope of Supply

SCOPE OF SUPPLY ACC PACKAGE:

ACC Design AspectSCOPE OF SUPPLY ACC PACKAGE:

Air-cooled steam condenser towerAir-flow control equipment. Wind and/or cell-partition wallsSteam-bypass heating system Air removal equipmentCondensate storage tankCondensate pumps Steam ducts and expansion jointsCondensate drain and air-removal pipingInstrumentation, controls and alarmsPressure-relief device for protection of steam-turbine exhaust casingSteam-duct condensate drain system.The purchaser has the option of buying this complete system package, or requesting only a portion of it.

ACC Design AspectMECHANICAL SCOPE Finned-Tube Bundle Steel Structure Steam ducting Expansion bellows Condensate storage tank Ejector system Condensate Drain pump CEP pumps Condensate Drain tank Access ( Staircase/ Platform etc.) Piping valves Fan and Gear box Cleaning System ( DM water spray system) Hoists, Davits, Monorails Abatement Systems (Abatement systems may involve noise abatement devices,

wind screens, etc). Spare Parts

ACC Design AspectELECTIRCAL SCOPE

Fan motors/Pump motors Supplied with pumps can be split) Cables , Instrumentation & Power Cable MCC Distribution board/Control panel

Lightning Protection System

Instrumentation scope

Fan vibration, alarm, and cutout switches – remote

Gearbox lube oil pressure and level – local

Steam duct temperature sensors – remote

Steam duct pressure sensors – remote

Condensate return temperature sensors

Condensate level sensors – remote

Vacuum pump skid hogging flow rateWind speed and direction sensor

ACC Design Aspect

Instrument required for PG test

Turbine Exhaust Pressure – At least four pressure taps with basket tips, symmetrically

disposed, in the steam duct near the connection to the turbine exhaust flange

Turbine Exhaust Temperature – A minimum of one thermo well, in the steam duct, near the

connection to the turbine exhaust flange

Local Wind Speed and Direction – Anemometer and wind vane at least 3 m above the wind

walls, on the corner of the ACC facing the prevailing wind.Condensate Flow Rate – The flow element should be installed at a point at least 10 diameters of

straight pipe in the condensate line downstream of the condensate pump, with a removable

flanged spool that can be used to install an in-line flow transducer

Condensate Temperature – At least two thermo wells in the condensate tank

Isolation – valves on all drain inlets to the condensate tank

Fan Power Measurements – Accessible wattmeter taps where the fan power cables exit the

motor control center (MCC) or variable frequency drive (VFD) cabinets

ACC Vendors

Potential Vendor GEA Cooling tower India Shriam cooling Tower Cortell India Paharpur Cooling Tower Thermax SPX GEI Cooling system

ACC Cost variationsMajor Cost variations

Single header Design Vs Multi header Design Concrete Structure Vs Steel Structures Single Speed drive motors Vs Variable speed drive motors Auxiliary Power Consumption cost Multi row Fin tube design/ Single row fin tube design Steam Ejector Vs Vacuum Pump

ACC DESIGN ASPECTSACC Performance Characteristics

The ACC design point is frequently characterized by the difference between the condensing

temperature (Tcond) and the entering air temperature (Ta inlet), known as the initial temperature

difference (ITD).

ITD = Tcond – Ta inlet Equation -1

For a given ACC, the heat load Q [Btu/hr (W/s)] is related to the ITD by

Q/ITD = Constant Equation - 2

Alternatively, for a given heat load, the size (number of cells, heat transfer surface) is inversely

related to the ITD as ACC “Size” α 1/ITDβ Equation -3

where a low ITD corresponds to a large ACC.

ACC DESIGN ASPECTSACC Performance Characteristics

The ACC design point is frequently characterized by the difference between the condensing

temperature (Tcond) and the entering air temperature (Ta inlet), known as the initial temperature

difference (ITD).

ITD = Tcond – Ta inlet Equation -1

For a given ACC, the heat load Q [Btu/hr (W/s)] is related to the ITD by

Q/ITD = Constant Equation - 2

Alternatively, for a given heat load, the size (number of cells, heat transfer surface) is inversely

related to the ITD as ACC “Size” α 1/ITDβ Equation -3

where a low ITD corresponds to a large ACC.

ACC DESIGN ASPECTS

ACC Evaluation

Thermal Duty – It is important to verify that the thermal duty solicited (i.e., the amount of heat

to be rejected) is matched or exceeded by the supplier’s offering.

Qrequired - = m`steam x (h steam, (turbine exhaust) – h (condensate))

Q rejected = U x A x LMTD