06-04-2012, 02:06 PM
REAL TIME PLANT PARAMETER DISPLAY OF DADRI THERMAL
PROJECT REPORT Trainees.doc (Size: 232.5 KB / Downloads: 46)
BRIEF INTRODUCTION TO THE PROJECT
Our project “Real Time Plant Parameter Display of DADRI Thermal” has following objectives:-
1. To know the working of DADRI plant.
2. To understand the control unit of plant which is based on DDCMIS (discrete digital control monitoring and information system), under the department of computerized data acquisition system (DAS).
3. To find out the important parameter, that has to display. Connect these parameters to LAN (Local Area Network) and interface to computers using VISUAL BASIC6 programming language.
NTPC – WORKING (COAL TO ELECTRICITY)
COAL TO STEAM:-
• Coal from the coal wagons is unloaded in the coal handling plant.
• This coal is transported to the coal bunkers with the help of conveyors belts. Coal is then transported to the bowl mills by coal feeders. This coal is pulverized in the bowl mill where it is grounded to a powder form.
• The crushed coal is taken away to the furnace through coal pipes with the help of hot and cold air mixture from PA fan (primary air fan).
• Atmospheric airs, from FD fan (force draft fan) is heated in the air heaters and send to furnace as combustion air.
• Water from the boiler feed pump passes through economizer and reaches the boiler drum.
• Due to heat and density difference the water rises up in the water wall tubes. Water is partly converted into steam as it rises up in the furnace. This steam and water mixture is again taken to the boiler drum where the steam is separated from water. Water follows the same path while the steam is send to super heater for super heating.
• Flue gases from the furnace are extracted by induced draft fan.
STEAM TO MECHANICAL POWER:-
• A steam pipe from the boiler conveys steam to turbine through a stop valve and control valve.
MECHANICAL TO ELECTRICAL POWER:-
• The turbine is coupled to 2-pole generator, which produce the electrical power (210 MW-typical) at a frequency of 50Hz and voltage 16.5kv (typical).
TRANSMISSION AND DISTRIBUTION:-
• Electricity is usually produced in the stator winding of large generators at about 16.5 to 25kv and is fed to terminal connection to one side of generator transformer that steps up the voltage to 132kv, 220kv or 400kv.
COMPUTERIZED DATA ACQUISITION SYSTEM (DAS)
The main purpose of the Data Acquisition System (DAS) is to acquire sensor data and to produce useful output information for plant operators in the form of displays and hard copies.
OBJECTIVES OF DATA ACQUISITION SYSTEM
• Monitor process operation to maintain on-line safe operation.
• Enhance plant life by helping identifying problem areas.
• Increase efficiency of operation
• Increase the reliability and availability of the process.
• Provide proper historical records of plant operation for review.
• Provide plant performance figures evaluating the same using on-line real time data.
• Provide facility for easy monitoring and proper tuning of automatic controls.
SALIENT FEATURE OF THE COMPUTER SYSTEM
Real Time Computer Characteristics:
A computerized DAS is a real time system and the computer selected for this application must be designed for real time. Essentially this means that the computer hardware features and must have a proven and efficient real time operating system. Some of the hardware feature that have been found to be important for DAS are as follows:-
• Memory cycle time of 1 µs or lower.
• Multiple external interrupt structure with a fair number of interrupts.
• Fast access disk in the order of less than 20 ms access time.
• Multipart memory banks with provision for interleaving.
• Memory expandability to at least 64k words or equivalent.
DISTRIBUTED DIGITAL CONTROL MONITORING AND INFORMATION SYSTEM.
The distributed digital control monitoring and information system are the state of art microprocessor based latest technology. These are close and open loop system, man machine interface and many other important features. It perform the functions of sequence and modulating controls, plant start up/shut down and plant operation on emergency conditions.
BASIC FEATURES OF DDCMIS
• 7 numbers of colour CRT’s are connected to MMIPIS functional block for control system operation, plant monitoring and information functions and alarm monitoring functions.
• Each of the colour CRT’s is interchangeable and provides complete control, monitoring, supervisory and display functions for control system variables and control system status.
ACTIVE CONTROL SYSTEM
In active control system, the signal conditioning is done per point basis, the modules AV42, AV05, AV06, XX02 take care of the analog signal acquisition from the field. The AV42 is used as the system interface to pressure /flow/level transmitters. The AV05/AV06 are used to scan RTD/Thermocouple directly. XX02 is a square rooting module use for computing flow from differential pressure measurement.
PASSIVE SIGNAL ACQUISITION
These cards are used for keeping the records of input data, taken through field. Some of the cards are as follows:-
Central Operation Station Z-LS3:
• For system operation and configuration.
• Connection for redundant system bus.
• Display of readymade and freely configurable pictures
• Alarm logging
• External storing and archiving of data on the fixed disk memory.
• Standard function program for operation, display and logging.
• 512 kb operating system on EPROM.
• 256 kb working memory on buffer RAM.
• One dual floppy drive.