Computerized Online Plant Performance-Based Monitoring Systems
The EzeeFit Power Performance Condition Monitoring System (PPCMS) offers
a powerful pc-based strategy for deducing overall plant efficiency and component
efficiencies incorporating real-time measurement of fuel consumption and
plant output to calculate overall plant heat rate or thermal cycle efficiency.
EzeeFit PPCMS Architectural Overview
The EzeeFit PPCMS (PPCMS) consists of three integral parts:
- PowerPAC™ Data Acquisition & Analysis Software
- PowerPAC™ Performance Analysis Module
- Data Acquisition Hardware
The EzeeFit PPCMS is backboned by our family of distributed data acquisition
I/O hardware. These multi-channel data collecting stations, designed to
be remotely operated by the EzeeFit PPCMS's PC, can be networked thoughout
the plant up to a mile away from the host PC.
PowerPAC™ Data Acquisition Software
PowerPAC™ is an engineering data acquisition, analysis and data
management software package written for the IBM PC and compatible family.
PowerPAC™ is an integrated set of programs that provides direct data
acquisition capability with full online analysis, alarm checking and logging
and periodic printing and storage of input and calculated data. PowerPAC™
also contains a full featured data management program. Data Display formats
include logsheet displays, barcharts, real-time XY and stripchart trends
and animated process graphics.
PowerPAC™'s HMI allows operators to create and change data display
formats with ease and also incorporates capabilities to perform alarm
acknowledgments, data files copies, and system resets. The standard PowerPAC™
HMI operates with a keyboard. In the optimal system configuration, the
HMI is enhanced with touch screen support. Once the HMI mode is activated,
all procedures are accomplished through a user friendly menu button system.
The menu button options, execute with either a keyboard or touch screen,
function to consolidate procedures and navigate the operator effortlessly
through the desired tasks.
PowerPAC™ Plant Performance Analysis Module
In many applications, the user-programmed equation facility of PowerPAC™
may be insufficient to provide the degree of online data reduction and
analysis desired. PowerPAC™ has been designed to interact with analysis
modules called PowerPAC™ Analysis Modules (PAMs). The EzeeFit PPCMS
PAM includes a subset of thermodynamic algorithms for performing required
boiler and/or turbine cycle analysis will be based on your plant arrangement.
These subset routines include:
Boiler
Boiler calculations include measured performance by Input-Output, Heat-Loss
and Effectiveness methods. Pinch and approach temperatures are also
provided. Design conditions are used as a baseline for modeling boiler
off-design performance which provides expected performance data for
comparison. Overall boiler effectiveness provides a measure of actual
enthalpy change of the exhaust gas compared to maximum possible change.
Component effectiveness calculations can be provided if gas side temperatures
between tube sections are available. The effectiveness indicates how
much of the total available energy is extracted from the gas in terms
of percent. Both products of combustion and steam side conditions are
used in the calculations.
Steam Turbine
Steam turbine performance includes enthalpy-drop (isentropic) efficiencies
across turbine stages, corrected heat rate calculations, and effects
on turbine performance from controllable loss parameters such as turbine
back pressure, inlet steam pressure and steam temperature. Heat rate
penalties are provided in terms of dollars per kilowatt-hour.
Condenser & Cooling Tower
Condenser cleanliness is calculated in accordance with steam surface
condenser standards by The Heat Exchange Institute. Cleanliness is measured
as the ratio of actual heat transfer coefficient to an ideal coefficient.
Calculation of both the ideal and actual coefficients requires knowledge
of the circulating water flow rate. Flow is to be determined either
by direct measurement or from circulating water pump characteristic
curves and measured discharge pressure. Cooling tower performance calculations
include a prediction of cold water temperature out of the tower and
tower capacity. Manufacturers design data and performance curves are
used to predict a circulating water flow rate based on measured cold
water temperature and ambient conditions. The ratio of corrected water
rate (at test conditions) to the predicted water rate provides the tower
capacity.
Balance Of Plant
An overall plant cycle heat and mass balance includes calculation of
all major water and steam flows to/from major components. The deaerator,
flash tank, feedwater pumps and circulating water pumps are included
in the BOP analysis. The net plant cycle heat rate and kW output corrected
to summer/winter and ISO reference temperatures shall be provided. AGC
limits based on ambient temperature shall be calculated from a correlation
provided by the user.
Steam and Gas Properties
Properties of air and the constituents of combustion products are correlated
from Keenan, Chao & Kaye Gas Tables, 2nd Edition. The specific heats
are combined to provide a function for stoichiometric products vs. temperature.
Steam properties are calculated from correlations presented in a U.S.
Navy Cosmic Program. The correlations were developed using Keenan &
Keyes Thermodynamic Properties of Steam.
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