ACKNOWLEDGEMENT WE HEREBY TAKE THIS OPPORTUNITY TO THANK NTPC LTD. TANDA FOR GIVING US THIS OPPORTUNITY TO CONDUCT OUR TRAINING IN NTPC LTD. , TANDA. WE ARE GRATEFUL TO MR. D. N. TIWARI(DGM,C&I) FOR ALLOWING US TO CONDUCT OUR TRAINING IN THE CONTROL & INSTRUMENTATION DEPARTMENT. WE ARE HEARTLY INDEBTED TO OUR PROJECT GUIDE Mr. LALIT KUMAR SINGH (Dy. SUPT,C&I)FOR PROVIDING US WITH DETAILED IN DEPTH KNOWLEDGE AND VERY USEFUL INFORMATION ABOUT THE PROCESSES AND SYSTEMS USED IN THE PLANT. HIS SUPPORT WAS INSTRUMENTAL IN OUR TRAINING BEING FRUITFULL.
WE ARE ALSO VERY TANKFUL TO ALL THE OFFICERS AND STAFF OF NTPC LTD. , TANDA FOR EXTENDING A HELPING HAND WHENEVER WE NEEDED IT. WITH REGARDS, RAVI KANT BHARTI B. TECH FINAL YEAR (VOCATIONAL TRAINEE) (B. M. A. S ENGG. COLLEGE, AGRA (U. P)) INTRODUCTION NTPC is the largest power generation company in India, with comprehensive in-house capabilities in building and operating power projects. It is producing 28,644MW.
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Its family consists of 18 coal based power plant producing (23209 MW) and 8 gas based power plant having a capacity of (5435 mw). It is also setting up a hydro based power plants having capacity of 2471MW. It is one of the largest Indian companies with a market cap of more than US$50 BILLION and has total assets of around US$ 20 BILLION. In this firm government has 89. 5% stake and 10. 5% with public. NTPC is ranked 463rd biggest company in the world, 5th biggest Indian company and 2nd largest Asian power generator. It produces 26350MW which is 20. 18% of the total 130,539MW of all India consumption.
More than one-fourth of India’s generation with one-fifth capacity. The next largest power utility owns 7. 9% of market share in terms of capacity and 8. 12% of share in terms of units generated. NTPC’s vision is to become world class integrated power major, powering India’s growth, with increasing global presence. It also develops and provides reliable power, related products and services at competitive prices, integrating multiple energy sources with innovative and eco-friendly technologies and contributes to society. NTPC stations are regular recipients of CEA’s meritorious performance awards.
This firm is also well concern about the environmental factors. It uses world’s largest ESP’s and also gives emphasis on environmental monitoring along with efforts to increase energy efficiency. BRIEF HISTORY OF THE POWER PLANT(TANDA) This prestigious power plant was inaugurated by late Prime Minister “Smt. Indira Gandhi” in 30th December 1981. It is located 22km away from the distt. Of Akbarpur (Ambedkar Nagar) and 60km(Approx) from Faizabad in the state of Uttar Pradesh. The capacity of the Power Plant is 440MW consisting of the four units each of 110MW capacity. This Power plant originally was owned by U. P.
State Electricity board but the level of performance that is P. L. F. (Power load factor) deteriorated which was taken over by NTPC at the date of 15th January on the year 2000 and It’s now successfully run by the co-operation work of engineers, workers, helpers and the other people who indirectly help the growth of this power plant and is now running an average of 85-90% (PLF). In the starting period of acquisition the PLF was these units were supplied, erected and commissioned by M/s BHEL. The Power house was located on the bank of river Saryu and West of the existing Mehripur pumping station of the Tanda canal system.
Necessary land, water and transport facilities are available. Land facility:- 1 . Land for Power Station including storage yard, Marshalling yard, Switching yard :- 120 hectares 2. Land for ash disposal 160 hectares 3. Land for colony 100 hectares Water facility:- 1. Water for once thru cooling 726. 5 cusecs 2. Water for cooling tower 45. 0 cusecs Transportation facility:- Power station is on Tanda-Faizabad also connected to Akbarpur-Faizabad. Nearest railway station 13km far (surapur).
Akbarpur is situated on Lucknow–mughalsarai Railway track. The distance of plant from Akbarpur is 30km. Tanda town is about 8km far from plant. Production & Transmission:- The 4*110MW power electricity is produced at the station using four different units. Each unit generates 110MW power. The arrangement of each unit is same. Since it is a thermal power plant, coal is used as the main source of energy. This coal is mainly supplied from the Dhanbad(Bihar) and other places. Generated electricity is supplied to following station:- 1. >Sultanpur 1 3. >Gorakhpur . >sultanpur 2 4. >Basti Since this power plant had been undertaken by NTPC in 2000 its performance in terms of power factor load(PLF) is improved in a great manner and can be observed from the given graph: FAMILIARIZATION OF THE POWER PLANT BASIC OPERATIONS OF A POWER PLANT Coal to Electricity Generating steam from coal Conversion of thermal energy to mechanical energy Generation and load dispatch of electric power. Coal to Electricity NTPC, Tanda is a thermal power station which produces electricity by using a non-renewable source of energy i. . coal. Coal is converted into pulverised form to enhance easy burning. The heat generated is used to convert water to steam which is further used to move the turbine to produce electricity. NTPC, Tanda is capable of producing a total of 440 MW of electricity. The main area of concern in any power plant is to increase the efficiency of producing electricity along with maintaining the previous best known efficiency The thermal power plant uses a dual ( vapour + liquid) phase cycle. It is a closed cycle to enable the working fluid to be used again and again.
The cycle used is “Ranking cycle” modified to include super heating of steam, regenerative feed water heating and reheating of steam. The figure shown below describes “Ranking cycle”. On large turbine it becomes economical to increase the efficiency by using reheat, which is a way of partially overcoming temperature limitations. Basic Power Plant Cycle The above figure shows the ranking cycle graph which is used in a power plant. The paths shown below the figure represents the complete the whole steam and heat cycle as followed in different operation cycles of a power plant. Factors affecting thermal power plant efficiency:
BOILER: 4 no of radiant dry bottom natural circulation, vertical water tube boiler with single reheat 380ton/hr of steam pressure 160kg per square cm at 540 degree centigrade of temperature. TURBINE AND TURBO GENERATOR: 4 no. of 110 MW each. WATER TREATMENT PLANT:4×30 ton/hr capacity. OUTER SUBSTATION: a) Power Transformer: 4 no. of 125 MVA 11/220 kVA. b) Reverse Transformer: 2 no. of 30/20/10 MVA 220/66/33 kVA. RATED PARAMETERS: Rated parameter related to output: 110 MW. Economical Output: 95 MW. Rated Speed: 3000 rpm. Rated temp. of steam before steam valve: 540*C. Max. emperature of steam before stop valve: 543*C. Rated temperature of steam before IP casing: 540*C. Max. temperature of steam before IP casing: 543*C. Rated pressure of steam just before stop valve:130 atm. Max. pressure of steam just before stop valve: 136 atm. Normal pressure of steam before IP casing: 31 atm. Max. pressure of steam just before stop valve: 37 atm. Cooling water temperature: 32*C. SYSTEM OF THE TURBINE: 2 Stop valve, one on either side of HP casing. 4 Control valves, 2 on either side of HP casing. 2 Stop valves, one on either side of IP casing. 2 Interceptor valves, one on either side of MP casing. Row circuit wheels, 8 moving wheel in HP cylinder. 8 Non regulated extraction and one reheat. Weight of HP rotor (approx. ): 5,500 kg. Weight of IP rotor (approx. ): 11,000 kg. Weight of LP rotor (approx. ):24,000 kg. Direction of rotation: Clockwise looking at the turbine from the pedestal 1. Barring speed: 62 rpm. DETAILS OF TANDA 110 MW # TG is designed by M/S SKODA supplied and manufactured by BHEL. # TG are supported by 7 journal bearings & coupled by 3 rigid couplings. Bearing no. 2 is thrust cum journal bearing. # HP TURBINE: Two concentric casing horizontally splitted up.
Double Row single circuit wheel and 8 impulse stage wheels. # IP TURBINE: Two concentric casing horizontally splitted up, 12 stage out of which integratelly forged with shaft & 4 shrunk fitted. # LP TURBINE: 2X4 reaction stages when steam flow is diabolie. All 8 wheels are shrunk fitted. # LP HEATERS: 1, 1A, 2, 2A are vertically mounted on LP casing. #EXTRACTION: 8 uncontrolled extraction, 3 from LP turbine, 4 from IP turbine and 1 from HP outlet. #BARRING GEAR: 62 rpm between LP and generator. INTRODUCTION TO STEAM TURBINE
The steam turbine is the prime mover in which the pressure energy of the steam is transformed into the kinetic energy of the rotor and later it is converted into electrical energy. CLASSIFICATION OF STEAM TURBINE 1. According to the no. of pressure stages : a) Single stage turbine, b) Multistage turbine. 2. According to the direction of steam flow: a) Axial turbine , b) Radial turbine. 3. According to the no. of cylinders : a) Single cylinder turbine, b) Double cylinder turbine, c) Three cylinder turbine, d) Four cylinder turbine. 4. According to the method of governing : a) Throttle with turbine, ) Turbine with nozzle governing. 5. According to steam condition at inlet to turbine: a) Low Pressure Turbine: Using steam at a pressure below 5 atm. b) Medium Pressure Turbine: Using steam at a pressure between 5 atm. to 40 atm. c) High Pressure Turbine: Using steam above 40 atm. 6. According to action of turbine: a) Impulse turbine, b) Reaction turbine. PARTS OF STEAM TURBINE BLADE: 1. BLADE: Blades of turbine are classified in following manner: # According to steam action: a) Impulse turbine, b) Reaction turbine. In case of Impulse turbine blade, pressure drop does not take place in moving blades.
While in case of Reaction blade, pressure drop takes place in moving blades. #According to Position: a) Fixed Blade b) Moving Blade. # According to construction: a) Free standing blade: This type of blade is not covered by anything and freely stand on the shaft of turbine. b) Shroud blade: This type of blade is covered by a plate of iron on the tip of the blade. c) Laeed wined blade: When the blade is tightened by thick wire, it is called Laeed wined blade. It is also called ribbon wined or Damping wined or Laeing wined blade. NOMENCLATURE OF BLADE CONSRUCTION OF FIXED AND MOVING BLADE
CONSTRUCTION OF IMPULSE AND REACTION TURBINE 2. ROTORS: The three rotors of turbine are supported on only five bearings, the thrust cum journal bearing being common to HP and MP rotates. It is the rotating part of turbine. It is also termed as Shaft. It has following classification: a) Flexible Shaft: The working speed of such type of rotor is below their critical speed. b) Rigid Shaft: The working speed of such type of rotor is more than their critical speed. 3. BEARING: Bearings are classified in following manner: a) Friction Bearing: In such type of bearings there is a line of contact between contacting surfaces. ) Antifriction Bearing: In such type of bearing there is a point contact between contacting surfaces. In NTPC Tanda, journal bearing which is a type of friction earing is used to support parts. There are 7 journal bearings among which second one is thrust cum journal bearing. 4. COUPLING : Rigid type of coupling is used in NTPC Tanda to connect the shaft of turbine. 5. BEARING PEDESTAL: Two bearing pedestals, front and rear. The front bearing pedestal carries all the governing system components, MOP and front HP bearings. The rear bearing pedestal carries the thrust bearing and its protection equipments.
STAGE: Pair of moving and fixed wheel is called a stage. No. of stages in each turbine: HP: 8 stages IP: 12 stages LP: 2×4 stages Regenerative cycle: There are 8 stages: LPT: 3extraction IPT: 4extraction HPT: 1 extraction in outlet of HP. Among which: Ext. 1 to5: LP Heater Ext. 6: Deaerator Ext. 7: HP Heater 1 Ext. 8: HP Heater 2 6. BALANCING HOLE: Balancing hole is provided in blade for the passage of steam. In NTPC Tanda, it exits in HP&IP turbine. AXIAL SHIFT: The value of axial shift is 0. 3mm. DIFFERENCE BETWEEN IMPULSE AND REACTION TURBINES. PARTICULARS IMPULSE REACTION TURBINE: 1.
Pressure drop only in nozzle not in both blades in moving blade 2. Area of blade channel constant varying 3. Blades profile aerofile 4. Admission of not all around all around steam 5. Power not much power much power 6. Space require less space require more space 7. Efficiency low high 8. Blade not difficult to manufacture. DIFFERENE IN NOZZLE AND THROTTLING GOVERNING: S. N. ASPECT THROTTLE NOZZLE CONTROL CONTROL 1. Throttling loses sever no throttling loses 2. Partial admission low high losses 3. Heat drop lesser higher 4. Use in both turbine in both turbine 5. Suitability small turbine medium and larger turbine
STEAM ADMISSION: In case of impulse turbine:- Steam admission does not take place all around. There is a 4 arc steam admission in impulse turbine. In case of reaction turbine:- admitted all around the rotor. STEAM EXPANSION IN TURBINE: Steam coming out from super heater at 540degree C and 139kg per square cm. Three cylinders of 2 set of main stop and governing valve arrangement on either side of HP casing and each set consist of one stop valve and 2 governing valve assembling series. The steam from the boiler is admitted the reheater where it heated at original temp.
The reheated steam is taken to IP casing through combined stop and interceptor valve arrangement at either of IP casing. The exhaust from the IP casing has taken directly the LP casing. The steam expanded in the LP turbine to a very low blade pressure which is maintained by the condenser below atmospheric pressure about 3% of makeup water is required to condensate the losses of cooling water due to evaporation in cooling tower. Finally steam exhausted by LP turbine is condensed in the surface type condenser type cooling water following through a large no. of tubes.
The HP, IP &LP turbine coupled in series and mechanical power generated from team transmitted to generator. REGLUATION AND SAFTY EQUIPMENTS FOR TURBINE PREPARATION: The scheme of regulation of turbine is regulated by four governing valves (GV) on the inlet to the HP parts and by two interceptor valves (IV) on the inlet to the LP parts. The amount of opening at any instant of these valves given by preparation of secondary oil which is indirectly dependent upon the primary oil preparation and directly upon the spring fence in the transformer and incidental dependent upon the portion of limiter (LT) during the stand all oil scouting.
SPEED SENSING ELEMENT: The speed sensing element is located on the external of HP rotor maintain the preparation in circuit of primary oil which is directly proportional to the square of speed of 2850 to 3360 rpm correspond the primary oil preparation of 2. 17 to 2. 99kg at an oil temp of 50 degree C under the same condition. The speed of 3000 rpm corresponds to a preparation of approx. 2. 38atg. TURNING GEAR: It is located on the bearing pedestal between LP part & the generator at intended to rotate the rotor at 62rpm before the commencement of start of apparatuses.
This prevents over warming up of rotor. PNEUMATIC CONTROL SYSTEM IN TURBINE: The pneumatic control system provided to the turbine are liable on main controlling of the valve of extraction and gland sealing system all element the final hazard associated with hydraulic system for the pneumatic system. Air is required at pressure 10atm &temp 80 *C. AIR TANK: It has capacity 2. 5 cubic metric tank is clamped to ground max pneumatic permitted. Inside the tank pressure 10atm &temp 80degree C. The air tank provided with two air relief valve at the top and a drain crook at the bottom. AIR VALVE:
Air valve each is provided for the two cold reheat flap. The fine extraction valves monitor the admission and release of compressor air inlet these equipments. Each air valve has an electromagnetic through which can be controlled automatically. All the air valve and these associated equipment are located in instruments box. EXTRACTION VALVE: Pneumatic controls non-return valve. These are insulated in the fine extraction line. Each valve is designed according to the steam. CRITICAL SPEED: Maximum speed of rotor at which resonance or vibration starts at high amplitude is called critical speed.
O Critical speed of generator: 2150rpm. O Critical speed of IP turbine: 1570rpm. O Critical speed of HP turbine: 3460rpm. O Critical speed of LP turbine: 1500rpm. LIMITING OPERATIONAL PARAMETERS: The operation of turbojet at a particular load in range 80-110MW is considered as stabilized operation provided that parameters of steam do not fluctuate and no serious deviation appear in the operation of set. During such stable operational period, change of load and other operating condition must be to the minimum extent possible.
It is to be noted must be maintained at the rated valve only. STEAM PRESSURE AND TEMPRATURE: O PRESSURE: During any twelve month operational period, the average steam pressure is not allowed to exceed the rated value. In maintaining this value, the rated steam pressure is not allowed to exceed 110% of the rated pressure. However, the pressure increase upto120% of rated pressure may be permitted provided the total amount of pressure fluctuation between 110% to 120% and rated pressure does not exceed a total of 12 hrs during any twelve month operational period. O TEMPERATURE:
During any twelve month operational period, at any turbine inlet point , the average admitted steam temperature is not allowed to exceed rated temperature . While maintaining this average value ,the admitted steam temperature is not allowed to exceed the rated temperature in excess of 8*C . However in exceptional cases, the temperature may momentarily be allowed to exceed the rated temperature by 14*C maximum, provided the total amount of the period of operation, between the limits of 8*C and 14*C does not exceed 400 hrs in any of 12 month operational period.
The turbine operation between the range of 14*C to 28*C in excess of the rated steam temperature is admissible provided the total operational duration between these limits does not exceed 80 hrs/day any 12 months operational period. Steam is supplied to the HP and MP casing inlet ports through two parallel supply lines; the maximum continuous difference in steam temperature in the individual steam line is allowed to be 17*C ;however ,if the deviation do not exceed the duration of 15 min the steam temperature difference is allowed to be 28*C maximum . DESCRIPTION OF PARTS
STOP VALVE: Stop Valve is used to stop or open the supply of steam coming through main stream tube, in HP Turbine. CONTROL VALVE: Control Valves are used to control the supply of steam in HP Turbine after passing the stop valve. It is 4 in number; two are on either side of HP Turbine. INTERCEPTOR VALVE: Interceptor Valve is between HP. Turbine and IP Turbine to regulate the supply of steam. BEARING: There are 7 bearings in TG set, out of which 6 are journal bearing and one is thrust cum journal bearing. 1,3,4,5,6,7: journal bearing; 2: thrust cum journal bearing.
There is sliding friction between the rotor and bearings. Bearing 1, 3, 4, 5, 6, 7 resist only radial load while bearing 2 resists both radial and thrust load. The rotor slides on bearing. Hence there is sliding friction. The inner surface of bearing is made of softer material called BAVIET. There is a little clearance between the rotor and inner surface of bearing where lubricating oil film is formed. Lubricating phenomena of oil occurs through wedging action. CONDENSER: A steam condenser is a device or an appliance in which heat of steam is absorbed by water and thus steam condenses.
TYPES OF CONDENSER: a) Jet Condenser, b) Surface Condenser. In NTPC Tanda, Dry Surface type condenser is used. Surface Condenser: SPECIFICATION OF SURFACE TYPE CONDENSER USED IN NTPC TANDA: 1. No. of condenser in each unit = 2 2. Condensers are supported on: 48 spring no. in each unit. 3. Type of condenser: Dry Surface type. # Cooling water inlet is from bottom. # Cooling water outlet is from top. #Inlet and outlet cooling water connection are located at one side only. #Other end of condenser has been left freely for expansion & contraction reason. 5. Cooling area of each condenser = 3380 sq. 6. Quantity of cooling water required for two condenser = 15400 cubic meter at 33*C. 7. Steam flow to condenser = 267 ton/hr. 8. No. of passes = 2. 9. Condenser tube outer diameter = 22 mm. Inner diameter =20 mm. , Thickness = 1 mm. 10. Condenser tube material: cupronickel (90% Cu + 10% Ni) 11. Length of tube = 7. 5 m 12. No. of tube = 13800. GLAND STEAM CONDENSER: Gland steam condenser is used to condense the steam leaking through turbines. HOT WELL: Hot well is used to store water formed through condensation of steam coming from outlet of LP turbine into condenser.
It is below condenser. CONDENSATE EXTRACT PUMP(CEP Pump): Condensate extract pump (CEP) is used to extract water from hot well and to supply main mechanical ejector. It is in 3 of number out of which any 2 are in running stage at any time. BOOSTER PUMP: Booster pump is used to pump the drip water formed due to partial condensation of steam in low pressure heaters. The outlet of booster pump is connected to the outlet of 5th low pressure heater. STEAM AIR EJECTOR: To maintain vacuum in condenser air ejector is used are of two types of air ejector is used: 1. Mechanical Ejector . Vacuum Pump. Here in NTPC Tanda Mechanical ejector is used . It works on venturimeter principle. There are two type of mechanical ejector: a) Starting Mechanical Ejector b) Main Mechanical Ejector It is used to remove air from the mixture . In case of ejector used for steam plant where a high vacuum pressure is maintained in the condenser . It is necessary to use two mechanical air ejector in series to obtain maximum vacuum . Main mechanical ejector is also used for heating of water on account of steam used in Mechanical ejector. There are 4 nozzles in two ejectors.
This also works as heat exchangers. DEAERATOR: It is used to separate out dissolved oxygen and air from water coming from low pressure heater . Oxygen and air is separate out from water in order to check corrosion of pipes and other equipments. In deaerator, water is sprinkled out from nozzles; it is called atomization of water. The deaerator is situated at a height in order to have a high pressure head for having a good efficiency of boiler feed pump. BFP works as suction and discharge of water. While suction process, there may be caviation which can damage the impellers of BFP.
To avoid caviation FST is situated at a reasonable height. FEED WATER STORAGE TANK (FST): Feed water storage tank is used to store water for B. F. P. It is situated below deaerator. Generally the whole set is termed Deaerator. BOILER FEED PUMP: Boiler feed pump is used to supply water at a high pressure of requirement to boiler. It is the equipment used having the maximum input of energy in the plant. The pump used is centrifugal pump. Each of the unit has two B. F. P. MECHANICAL SEAL COOLER: Mechanical seal cooler is used for cycling of feed water leaking through boiler feed pump.
Thus it stops more leakage of water. ECONOMIZER: An Economizer is a device in which the waste heat of flue gases is utilised for heating the feed water in steam generating set. LOW PRESSURE HEATER(LP Heater): Low pressure heaters are used to heat water coming from main mechanical ejector. They are 5 in number. HIGH PRESSURE HEATER: High pressure heater is used to heat water coming from BFP. From high pressure heater water is fed to economizer. OIL PUMPS:- MAIN OIL PUMPS(MOP) This is centrifugal single stage double suction pump mounted directly on the HP rotor extrusion & is housed in the pedestal bearing.
In normal operation of turbine, the completely quantity of oil required by turbo-set is supplied by main oil pump. MOP supplies oil the injector for lubrication and for the governing & oil operated protection. The lubrication oil is collected in oil cooler the 42 to 45*C before entering the bearing 3. Oil cooler are provided. STARTING PUMP: The rotor driven main oil pump can operate system only at about 2800rpm. Hence to meet the required of starting and sloping the system. EMERGENCY PUMP: In discharging oil to the bearing when the lubricating oil pressure drop to a present valve.
There are two EOP on driven by 10kw AC motor & the 2nd by 9. 2kw DC motor located at ecometer with suction from the oil tank. TYPE OF LUBRICATING OIL USED IN NTPC TANDA:- Servo prime 46 supplied IOCL. OIL REQUIREMENT:- O Total required of oil for entire set: 23,400 lit. O Out of which turbine required: 19,000 lit. O Generator required: 4,400 lit. O Make up oil for set: 38lit/day. HEATERS: There are 8 heaters provided from each 110kw, two high pressure & one heaters act as a dearator of the condenser. For shake of optimization essentially equal feed water temp rise cross LP Heater 1 to 5 dearator & HP heater. is aimed at the rise across the other. For the equal feed water enthalpy rise for the heater is impossible. In actual practice, turbine has naturalextraction. Since extraction of steam can be removed at these points with little pressure. Cycle can be adjusted for equal enthalpy rise. GLAND STEAM SYSTEM(GSC):- The turbine rotors needs the protection of casing at both ends so that they must be coupled at the place where the rotor must be sealed against the atmosphere so that the high pressure steam inside the take out waste fully or at the cold atmosphere air does not enter the casing in HP & IP.
Both the ends have steam at a pressure much higher the atmosphere in LP casing. This pressure is below the atmosphere. Hence glands are provided at casing end. BASIC CYCLE OF A POWER PLANT For proper functioning of a power plant ,its working operation has been divided into following main operation cycles. Steam cycle Feed water cycle Condensate water cycle Primary air cycle . Flue gas cycle Secondary air cycle EXPALAINATION OF POWER PLANT CYCLES STEAM CYCLE: This cycle basically deals with the flow of steam at different pressure and temperature to different turbines namely HP,IP and LP turbines which is connected to the generator.
It can be explained from the figure shown below HP From Final S/H MP LP TURBINE GENERATOR R/H 32 Ksc,535 `C MAIN STEAM 130Ksc 535 `C 34 Ksc,370 `C condenser Hot well STEAM CYCLE Hp By-pass Steam coming out from super heater at 540degree C and 139kg per square cm. Three cylinders of 2 set of main stop and governing valve arrangement on either side of HP casing and each set consist of one stop valve and 2 governing valve assembling series. The steam from the boiler is admitted the reheater where it heated at original temp.
The reheated steam is taken to IP casing through combined stop and interceptor valve arrangement at either of IP casing. The exhaust from the IP casing has taken directly the LP casing. The steam expanded in the LP turbine to a very low blade pressure which is maintained by the condenser below atmospheric pressure about 3% of makeup water is required to condensate the losses of cooling water due to evaporation in cooling tower. Finally steam exhausted by LP turbine is condensed in the surface type condenser type cooling water following through a large no. f tubes. The HP, IP &LP turbine coupled in series and mechanical power generated from steam transmitted to generator. Feed water cycle :- this cycle deals with the flow of water to boiler feed pump from feed storage tank ,which is later fed to the boiler drum passing through high pressure heater and economizer D/A FST (165-170)°C 170°C HPH-1 HPH-2 205°C 240°C ECONOMIZER 1&2 340°C BOILER DRUM 2 B. F. PUMP FEED WATER CYCLE This system plays an important role in the supply of feed water to the boiler at requisite pressure and steam/water ratio. his system starts from boiler feed pump to feed regulating station via HP heaters. Boiler feed pump : this pump is horizontal and barrel design driven by an electric motor through a hydraulic coupling. all the bearings of the pump and motor are forced lubricated by oil lubricating system. The feed pump consists of pump barrel into which is mounted the inside starter, together with rotor. water cooling and oil lubricating are provided with their accessories. The brackets of the radial bearing of the sunction side and the radial and thrust bearing of the discharged side are fixed to low pressure cover.
High pressure heater: these are regenerative feed water heater operating at high pressure and located by the side of turbine. It is connected in series on feed water side and by such arrangement the feed water after feed pump enters the hp heater. the steam supply to these heater from the bleed point of the turbine through motor operated valves. Condensate water cycle: It deals with the water flowing through the condenser which plays an important role in increasing the efficiency of the plant. It consists of a feedback path from main ejector to hot well. HOT WELL 40°C LPH M/E LPH3 LPH4 LPH5 D/A 3 CE PUMP 150°C
HEIGHT 42M FEEDBACK PATH CONDENSATE WATER CYCLE 45 °C The steam after condensing in the condenser known as condensate, is extracted out of the condenser hot well by condensate pump and taken to the de-aerator through ejectors, gland steam cooler and series of LP heaters Condensate pump : the function of these pumps is to pump out the condensate to the deaerator taken to the de-aerator through ejectors, gland steam cooler and series of LP heaters. This pump is rated generally for 160 cubic metre/hour at a pressure of 13. 2 kg/cm square. LP heater :- there are four lp heater in which 4 extraction are used. hese heaters are equipped with necessary safety valves in the steam space level indicator. the condensate flows in the u tube in 4 passes and extraction steam washes the outside tubes. Deaerator : the inner corrosion can be prevented by removing dissolved gases from the feed water. it can be achieved by embodying into the boiler feed system a deaerating unit whose function is to remove the dissolved gases. it works on two principles:: henry law and solubility law. Solubility law : solubility of gases decreases with increase in pressure and /or decrease in pressure.
Henry law : the mass of gas with definite mass of liquid will dissolve at the given temperature and is directly proportional to the partial pressure of the gas in contact to liquid. * Primary air cycle :- In this cycle, air is used to carry pulverized coal from mill to the burning zone of boiler. * Flue gas cycle :- In this cycle, gas containing waste materials are removed from the system using various techniques like electrostatic precipitator , ID fans etc. The flue gas, before being removed is used to heat the primary and secondary air. Secondary Air cycle:- In this cycle, fuel is mixed with air (known as secondary air) for proper burning of coal. BOILER * A STEAM GENERATOR IS A COMPLEX INTEGRATION OF THE FOLLOWING ACCESSORIES: 1. ECONOMISER 7. DIV PANEL 2. BOILER DRUM 8. PLATEN SH 3. DOWN COMERS 9. REHEATER 4. CCW PUMPS 10. BURNERS 5. BOTTOM RING HEADER 11. APHs 6. WATER WALLS ECONOMISER * Boiler Economiser are feed-water heaters in which the heat from waste gases is recovered to raise the temperature of feed-water supplied to the boiler. It preheats the feed water by utilizing the residual heat of the flue gas. * It reduces the exhaust gas temperature and saves the fuel. BOILER DRUM * It is an enclosed Pressure Vessel * Heat generated by Combustion of Fuel is transferred to water to become steam * Serves two main function. * Separating heat from the mixture of water and steam. * It consists of all equipments used for purification of the steam after being separated from water. BOILER DRUM LEVEL CONTROL * Important for both plant protection and equipment safety. * Maintain drum up to level at boiler start-up and maintain the level at constant steam load. Decrease in this level will uncover boiler tubes and get overheated and damaged. * Increase in this level will make separation between steam and moisture difficult within drum. * Controlled circulation is required to maintain the difference in the density between water and steam with increase in pressure. DOWN COMERS * It carries water from boiler drum to the ring header. * They are installed from outside the furnace to keep density difference for natural circulation of water & steam. * Heating and Evaporating the feed water supplied to the boiler from the economiser. WATER WALLS These are membrane walls, no. of tubes are joined. * Vertical tubes connected at the top and bottom of the Headers. * Receives water from the boiler drum by down –comers. ADVANTAGES * Increase in efficiency * Better load response simpler combustion control. * Quicker starting and stopping * Increased availability of boiler. * Heat transfer is better * Weight is saved in refractory and structure * Erection is made easy and quick DISTRIBUTED CONTROL SYSTEM UNDERSTANDING A CONTROL SYSTEM On the basis of given figure CONTROLLER PROCESS SENSOR ERROR S. P C. V. + – S. P:=SET POINT C. V:=CONTROL VALUE EXPLANATION It is a closed loop or feedback system. * System is set to fixed value known as SET POINT. * Deviation of the measured value from set value describes the controlling action to be performed. * Control value to be sensed by sensor and the deviation from SET Pt. is measured and a Error signal is generated. Types of controller used in a power plant LOCAL CONTROLLER | Outdated controllersIndividual controller for each unit like turbine , boiler, generators etcManual monitoring | DATA ACQUISITION SYSTEM CONTROLLER | centralized data collection centre. Manual monitoring is done. Outdated technology. DISTRIBUTED CONTROL SYSTEM | Recent technology . topic to discuss in detail. | DDCMIS – TECHNOLOGICAL BACKGROUND PROGRESS OF INSTRUMENTATION USED TO IMPLEMENT AUTOMATIC PROCESS CONTROL * LOCAL PNEUMATIC CONTROLLERS * MINIATURIZED AND CENTRALIZED PNEUMATIC CONTROLLERS AT CONTROL PANELS AND CONSOLES * SOLID-STATE CONTROLLERS * COMPUTERISED CONTROLS (SUPERVISORY) * DIRECT DIGITAL CONTROL(DDC) * DISTRIBUTED MICROPROCESSOR BASED CONTROL Disadvantages of earlier Systems * Analog instrument panels required huge space, lot of wiring and are less user friendly for monitoring of large number of parameters. Accuracy obtained with solid-state controls is not good and they tend to drift with time. * Supervisory controls are inflexible as changing of control configuration requires change in routing of wires. * Use of centralized control leads to complete failure during shutdowns. Components of DDCMIS CONTROL SYSTEM MAN MACHINE INTERFACE & PROCESS INFORMATION SYSTEM DATA COMMUNICATION SYSTEM ( DATA HIGHWAY) BOP & CI SYSTEM * CONSISTS OF OPEN LOOP CONTROL SYSTEM (OLCS) AND CLOSED LOOP CONTROL SYSTEM (CLCS) * OLCS – THE SEQUENCE CONTROL, INTERLOCK OF ALL THE PLANT SYSTEMS WHICH ARE NOT COVERED IN THE SG-C&I AND TG-C&I.
THIS INCLUDES MAJOR AUXILIARIES LIKE FD/ID/PA FANS, AIR-PREHEATER, BFP/CEP/CWP/ BCWP , DMCWP/CLCWP AND ELECTRICAL BREAKERS. * CLCS – THE MODULATING CONTROL FOR VARIOUS IMPORTANT PLANT PARAMETERS, LIKE FW FLOW (DRUM LEVEL), FURNACE DRAFT, COMBUSTION CONTROL (FUEL FLOW AND AIR FLOW), PA HDR PRESSURE CONTROL, DEAERATOR/HOTWELL/HEATER LEVEL CONTROLS ETC. MAN-MACHINE INTERFACE AND PLANT INFORMATION SYSTEM * 64-BIT SERVER/OWS WITH HIGH-SPEED AND LARGE MEMORY (256/512 MB RAM, 8 GB HDD FOR SERVER AND 128/256 MB RAM AND 4/6 GB HDD FOR OWS) TO ENSURE FAST RESPONSE * PROVISION OF LVS CONNECTION TO OTHER SYSTEM THROUGH STATIONWIDE WAN * TRANSPARENCY NO 9 & 10 MMIPIS FUNCTIONALITIES * VPC OPERATION * OTHER OPERATOR INFORMATIONS THROUGH VARIOUS DISPLAYS * ALARMS, LOGS, HISTORICAL AND LONG TERM STORAGE. * PERFORMANCE AND OTHER CALCULATIONS BRIEF INTRODUCTION OF MAXDNA Bharat Heavy Electricals limited (BHEL), Electronics Division, has entered into a Technical Collaboration Agreement (TCA) for the manufacture and supply of new generation Distributed Control Systems ‘MAX1000+PLUS’ , for modern Power Plants & Industries, with MAX Control Systems (MCS) Inc USA, part of METSO Automation.
The MAX1000+PLUS is now re-named as maxDNA. where-in DNA stands for Dynamic Network of Applications. maxDNA is a network of applications where diverse hardware and software solutions co-operate to allow the plant to reach its greatest potential. BHEL’s Electronics Division has established itself in the area of Control & Instrumentation for new power plants as well as renovation and modernisation of existing power plants. A leader in the Indian Power Sector market, it has already supplied and commissioned above 200 sets of DCS for thermal, combined cycle and hydro sets all over the country and overseas. MCS Inc. USA, former systems division of Leeds and Northrup, USA, is an internationally reputed technology leader In both Power as well as Industrial process control systems, with 70 years of rich experience in the field. Applications maxDNA systems are used in many applications throughout the world including electric power generation, co-generation, cement, glass, ceramics, primary metals, chemicals and petroleum, water and waste-water treatment and incineration plants. BHEL offers a variety of solutions for Power Plants ranging from simple control systems to complex unified automation for Power Plants of any size.
The synergy of BHEL’s expertise in Power Plant Controls and cutting-edge technology of maxDNA provides for unified DCS solution for entire Power Plant comprising of Steam Generator, Steam Turbine Generator and Balance of Plant C&I. The state-of-the art control system is also configured for complete range of Hydro Turbine governing and auto sequence controls, SCADA systems and for wide range of industrial process applications. The spectrum of applications in brief are as listed. Power Plant Controls o Steam Generator Controls o Heat Recovery Steam Generator (HRSG) controls o Steam Turbine controls Industrial Steam Turbine Controls o Balance of plant controls o Data Acquisition and information management o Hydro Turbine Governing and Auto sequence controls o Generator and Switchyard controls o Electrical System controls o Fossil power utility plants o Combined cycle power plants o Captive power plants o Simple cycle power plants Industrial controls The maxDNA allows easy integration of third party devices and communication with external systems. The system also allows user flexibility to operate a small stand-alone control system to a mega control system with plant-wide automation.
Its open architecture permits the integration of process control, management information systems, local and wide area networks, PLC systems and SCADA systems BHELs integrated Automation and Information Management System maxDNA is a microprocessor based real time system. This system is designed on modular basis, allows scalability and provides operator the complete tool to increase the availability, efficiency and safe operating state with respect to the Process component. The maxDNA DCS product line provides regulatory control, sequential logic control, operator interaction through CRTs (MAXSTATIONS) and information management.
The MAXSTATION can be configured as an operator station, engineer’s station, historian (MAXSTORIAN), gateway, or link server (MAXLINKS) to foreign systems. It provides for high-resolution graphics utilising a powerful graphical user interface – MAXVUE. The maxDNA also provides a comprehensive set of tools (MAXTOOLS) for the development of system application, configuration and installation. maxPAC Process I/O maxPAC input and output modules connect thousands of process variables, controllable and element devices throughout the plant to the maxDNA Plant Automation System. axPAC I/O modules are available in a number of input and output configurations to match the electrical characteristics of the sensors, transmitters and controllable devices. Key Features High density I/O. · Isolated Input / Output modules. · Supports full redundancy. · Both local and remote installations. · Lower power consumption. · Self calibrated analog modules. · Remove and insert modules while powered. · Modules have colour coded faceplates for rapid identification. · Rotary address switches for fast set-up. · All the modules that require field power include a front mounted fuse disconnect and a LED fuse status indication. All discrete modules include front mounted LEDs for input / output state. · (15+1) bit Resolution for Analog inputs. OPERATING ENVIRONMENT MaxPAC I/O and related hardware comply with the following standards. · ESD – IEC 801-2. · Surge – IEEE-472-1974 (ANSI C37 90a) surge withstand test. · RFI-801-3 with the cabinet door closed. · Vibration – Sinusoidal vibration specification per SAMA PMC31. 1 using control room level; 1 mm displacement 5-15Hz, 0. 5G 15-150Hz. · Storage temperature – 26 to 70 Degree C. · Operating temperature 0 to 60 Degree C. · Relative Humidity; 5 to 90%, non-condensing.
SALIENT FEATURES – The DCS Data Highway speed is 10/100 Mbps. – Communication Network is full Duplex type. – Intelligent Switched Fast Ethernet for communication with redundancy. – 32 Bit Intel Multifunction Controller for OLCS & CLCS with WINDOWS CE Operating System. Intel Pentium IV OWS with WINDOWS 2000 for MMI / DAS. – Distributed Data base on RPUs. – On line documentation system. – Centralized Engineering Station for programming, configuration and downloading. – Dedicated links for other system. – Integrated SOE with 1 milisec resolution functions are envisaged. Multilevel security system are envisaged for different functions like engineering, database changing etc. – Optical isolation for I/O modules. – Scan time for critical analog signals is 20 milisec & others 100 millisec or above. – Execution time for control logics is selectable from 20/100/500 millisec. as per requirement. – Interchangeability of Engineering station and Operator Workstation, wherever necessary. – History with 1 second sampling rates and long term storage & retrieval. – Point database (Global Data) accessible at any station across the Network. – Selective I/O redundancies depending on process criticality. Enhanced graphic capabilities. – OPC complaint. – Status of modules available on OWS. – Controller logic is available on OWS (on-line). -Facility for simulation of control logic schemes with virtual processor. HARDWARE ENVIRONMENT maxDNA technology is used for monitoring and manage process control environment through a maxSTATION . it is used for man machine interface. maxSTATION can be set up as an operator’s workstation. it uses maxVUE graphical interface software to provide a graphical view of the process and comprises of both standard and custom display.
Engineer’s workstation is used for creating and maintaining configurations and process control documentation using maxDPU tools and maxVUE graphical configurator software. it is also used to create and maintain custom graphic displays using the maxVUE graphics editor software. maxSTATION collects and manages process and event history, reporting, and archiving using the maxSTORIAN history and archiving software. maxSTATION Hardware According to the function to be performed by a particular workstation determines its minimum hardware requirements.
Such as for collecting data one needs a larger hard diskthan operator’s workstation. So for its proper functioning it must meet the minimum hardware requirements. mxaDNA components The maxDNA Distributed control system consists of one or more maxDNA Remote Processing Units (RPUs) cabinets which contains, * maxDPU Distributed Processing Units (DPUs), the process controller, provides control and data acquisition functions. * Input/Output devices (I/Os) for monitoring and controlling the actual process. * One or more maxSTATIONs configured as operator or engineer workstations.
This technology is used for man machine interface. It is essential to have a network system between workstation and field for the interface. Network Overview maxDNA technology uses a client/server architecture. maxDPU acting as a server collects information, stores it and ultimately transfers the information to the appropriate maxSTATION clients . maxSTATIONs and maxDPUs communicate with one another via maxNET. The maxNET Network is a fully redundant 10/100 Mb per second Ethernet network using industry standard UDP/IP protocol for communications between Workstation clients and servers. axDNA POINT DATABASES: it is composed of point databases. A point databases created in maxDPU Tools, consists of hardware resources and control points. One configuration is permitted per DPU or DPU pair, which may serve a group of Remote Processing Unit cabinets. In a power generating plant, for instance, one configuration could represent a burner management strategy, another a boiler control strategy, and so forth. System resources consists of RPU’s H/W,DPU,I/O Modules, power supplies, etc. Control points consists of FUNCTION BLOCK custom BLOCK Standard block ATOMIC BLOCK EXPLANATION OF BLOCKS
Atomic Block : Function Block that implements smallest possible function in maxDPU. All Atomic Blocks are programmed into maxDPU. Standard Block: derived Function Block that is part of maxDNA product. All Standard Blocks are programmed using Atomic Blocks and/or other Standard Blocks. End users, operations or consultants cannot customize standard Blocks. Custom Block :derived Function Block that is made from Atomic Blocks, Standard Blocks and/or other Custom Blocks. New Custom Blocks can be built and existing Custom Blocks can be changed by anyone using maxDNA-engineering tools.
Operators may view pts from any configuration at any operator’s workstation provided the operator’s work station and DPU are attached to the same maxNET network and have read access to specified domains. Tasks performed by the maxSTATION : 1. ;Display real time data from any DPU on the maxNET network in a single graphic display. 2. ; Display trend or X-Y data from any DPU on the maxNET Network in a single display. 3. ;Access all control loops on the maxNET Network. 4. ;Display the current alarm summary display; available alarm information is typically restricted to a specific domain.
Working in maxVUE maxSTATION software requires the Microsoft Windows® operating system. It run as a standard windows application and respond to the mouse and keyboard like any other windows package. Input Devices The maxSTATION accepts a variety of input devices including: * MOUSE * TRACKBALL * Touch screen * Keyboard Use of mouse is similar to that in case of a computer. Using the keyboard maxSTATION can use both a normal QWERTY keyboard and an operator’s keyboard . Engineer’s keyboard is required in an engineer’s workstation. it is used to enter text and perform other function with special keys.
Operator’s keyboard has dedicated keys used to perform specific tasks such as acknowledging alarms or taking control action . ————————————————- maxSTATION is the hardware platform through which one can view and manage process control environment. It can be set up as an operator’s or engineer’s workstation and the compatible software must be installed, however security alerts are set , the protective key (dongle) and passwords are different . Each of the standard configurations is shipped with Processors and Power Distribution mounted and internally interconnected.
Connecting stations and DPUs to the maxNET NETWORK Workstations and maxDPUs communicate with one another over maxNET. a redundant Ethernet network. It is consists of two independent Ethernet networks named as “A” and “B”. it is assumed that “A” is independent clone of “B”. This network setup is consists of electrical and fiber optic cable fast Ethernet switches and fiber optic converters. maxNET is an open system and does not rely on a specific model of network hardware. In setting up this network, two types of wires are used metallic cable is used for interconnection inside the cabinets and for short distance runs through reas that are not subject to electrical noise. Fiber optic cable is used when it is necessary to span a large geographic area, to provide electrical isolation between equipment groups or to reduce noise pickup in electrically harsh environments. Both types of capable of carrying data at 10Mbps or at 100 Mbps. Network Layout Guidelines During lay out of this network one should must be considered the following factors like,Path from workstation to DPU. The number of switches must be kept minimum. It is good practice to restrict the number to “3” between any workstation and the maxDPU.
Keeping the number of switches to a minimum not only increases reliability but also make troubleshooting easier when a switch fails. The maxNET “A” and “B” networks must be completely separate from each other and from other network(the plant network). “A” and “B” cables must not be connected to the same Ethernet switch. Cables of network A and network B should not get mixed up. A’s cables must only be connected to network A Ethernet card or switch, similar is the case with network “B” for this reason only each of the connector has been labeled.
The rear panel of each processor slot must be similarly marked like “ A,B and P or LAN for a plant Ethernet connection). Cables assembled in cabinets and desks at the factory contain a two line label. The top line describes where the cable originates and the bottom line describes where the cable terminates. This dual network structure of the maxNET architecture provides high reliability through its redundancy. No single network element can fail and prevent communications between any workstation and maxDPU or DBM.
For more reliability network “A” and network “B” cables through physically separate paths when installed at plant site. Accidently, if bunch of cables get damaged it can be easily solved without interrupting the networks. Signal losses can be reduced by establishing the metallic network connection or unshielded twisted pair electrical cable. CABLE MINIMAL REQUIREMENT * Ethernet UTP 4 pair 24 AWG stranded wire for any runs less than 20 ft. * Ethernet UTP 4 pair 24 AWG solid wire for any runs greater than 20 ft. * Fiber optic cable:62. 5/125um multimode fiber with ST connectors.
Here we use plenum-rated insulation on the network cables for local fire codes require it and for cabinet wires standard PVC insulation is accepted. UTP cables comes in two varieties straight-through cable is used to connect different types of devices (workstation to a switch or a switch to a maxDPU). Crossover cable is used to connect similar devices(switch to switch). Some devices have both the ports crossover and straight-through cable may be used them. Cross over ports are typically labeled with an “X”. A single port on a device may be used as either a straight-through or a crossover.
Fiber optic converters have a switch labeled MDI/MDI-X. When a peripheral device is connected to the media converter we have to move the MDI/MDI-X switch on the converter to the MDI position. Ethernet switches are used to interconnect all nodes of the maxNET network. The switches used in a maxNET system must meet some minimum functional requirements. However these switches must meet certain requirements which are listed below: HADWARE DUPLEX SPEED maxSTATION Full duplex 10Mbps or 100Mbps maxDPU4F Full duplex 10Mbps or 100Mbps MaxDPU4E Full duplex 10Mbps DBM Half duplex 10Mbps Ethernet Switch Minimal Requirements
Must contain a minimum of two full-duplex 100 Base TX ports for connections to other switches. 120V ac 60Hz/240V ac 50Hz power 19 inch rack mounting Must allow the user to manually configure the speed and duplex settings for each port. Ethernet Switch Desired Features Support remote management (SNMP) to allow user to check and configure switch settings and to read and reset port statics,it greatly helps in system maintenance procedures. This is maxDNA maxDNA is the seamless combination of proven Plant Automation System hardware and a Dynamic Network of Applications specifically designed to meet the needs of electric power plants. axDNA is supported by a full range of life cycle services designed to increase the economic value of your plant. What makes the difference is that maxDNA was created by application developers knowledgeable in all aspects of the operation of power plants. Electric Power Generation Metso Automation offers turnkey solutions for all types and sizes of power plants. For large fossil fired plants Metso Automation exclusively uses the D-E-B coordinated control philosophy, an approach that assures the unified operation of the boiler, its inputs, fuel, air and feedwater, with the turbine-generator output.
The D-E-B system is a proven control strategy that is designed to meet the number one objective of the power plant – match generation to demand, under all conditions. Now in its fourth generation, D-E-B has been proven on over 900 large fossil fired power plants around the world – and it is only available from Metso Automation. Metso Automation is the leader in supplying systems and applications for eco-efficient power plants. Metso engineers designed and supplied the systems for world’s largest biofuelled power plant.
An advanced information management system was supplied to accurately monitor and report the plant’s various products (electricity, process steam and district heating) to ensure proper invoicing. Due to the boiler’s large size (550MWt) and wide range of fuels, accurate monitoring of fuel consumption and efficiency would be next to impossible without the advanced applications designed by Metso Automation. Over 4500 people are stationed in 37 countries around the world to provide long-term support for all Metso Automation installations. maxDNA configuration tools Summary
Connects to DPU4E and DPU4F – real or virtual 100% self-documenting – no off-line storage of database or diagrams Create & edit logic diagrams Rapid configuration speeds installation Extensive on-line tools to aid debugging Display & print logic diagrams What-you-see-is-what-is-installed for long-term ease of maintenance maxDNA Configuration Tools are comprised of maxTOOLS and maxVUE Graphical Configurator. It is the set of software elements which are used to configure, edit and maintain the Distributed Processing Units (DPU4Fs and DPU4Es) in a system. maxDNA Configuration Tools can run in any maxSTATION. axDNA Configuration Tools are used to configure the modulating control strategies, the binary logic control strategies, the DPU database, sequence of events reporting, alarm types and setpoints, loop execution times, I/O card, bus, termination interface, and maxNET interface in a DPU. maxTOOLS A configuration often starts with bulk data entry. maxTOOLS takes advantage of relational database methodology to support rapid and efficient entry and manipulation of data. A flexible import of data supports initiation of maxDNA databases from customer databases, speeding time of entry as well as reducing the potential for errors. axVUE Graphical Configuration maxVUE Graphical Configuration takes over after bulk data entry to provide object interconnection, and eventual on-line debug of the process. Both the modulating and the binary or logic control loops are configured in a graphical format using standard maxDNA algorithms and function blocks. A partial list of the current library is listed in the table on the following page. The initial step is the selection of the DPU database from the overall project database. The DPU database is then connected to the process I/O bus and the individual I/O cards that convert the field signals that are read by the DPU software.
The assignment of I/O cards and channels per card is done at this time. Sequence-of-events digital inputs points are identified to enable the DPU to read the millisecond timestamps associated with all changes of state for these selected points. Each control loop is configured by selecting an algorithm and connecting the inputs from one algorithm to the outputs of other algorithms to achieve the desired control strategy. Since maxVUE Graphical Configurator is object oriented, a configured loop can be reused as the starting point in configuring similar loops such as multiple coal mill temperature loops.
Algorithms can be grouped into custom function blocks which can be configured as a single block with only the block inputs and outputs shown. Partial List of Algorithm Function Blocks| Absolute value Add / subtract Multiply Divide Mod Exponential Power Square root Totalizer Calculate Signal select Leadlag Analog input buffer Analog output buffer Digital input buffer Digital output buffer Pulse input / output buffer Quad PAT buffer Thermocouple in buffer RTD input buffer Device logic Sequence master Sequence step First out Timer on Timer off Timer pulse
Trigger edge any Trigger edge fall Trigger edge rise Serial link bit pack Serial link bit unpack Alarm reporter Alarm clock Output driver buffer| Auto manual Limiter PID Feed forward Participation member Participation master Controller combining PAT out Control select Control add (bias) Control multiplier (ratio) Control divider 1 Control divider 2 Function generator Quality force Not And Or Exclusive or Greater than Less than Equal Not equal Flip flop reset dominant Flip flop set dominant Flip flop no dominant Analog tag Digital tag Steam properties
Flow compensation Level compensation User object Group Counter Timer| As part of the configuration process, the execution class is also selected from the three available time classes that are typically set at 40, 100, and 500 milliseconds. maxDNA Configuration Tools allow the user to view the structure details and connections at various levels to provide both a “functional” representation of the strategy (see figure 1) and a highly detailed “schematic” representation showing all available data (see figure 2). Figure 1 – Functional Representation of a Strategy
Pan and zoom capabilities are provided to facilitate focus on the portion of the loop being investigated or configured. Drag and drop cursor control is utilized as well as line connection between algorithms as selected by the engineer. maxDNA Configuration Tools also provides automatic cross referencing of algorithms and signals plus direct access via a single keystroke to these cross referenced items. Each and every control loop, signal, and algorithm can be annotated to enhance understanding of the control strategy, unique I/O configurations, or existing plant peculiarities.
This information can be displayed on the CRT and / or printed on the drawings. Diagnostic checks are integrated into maxDNA Configuration Tools to prevent errors such as connecting a logic signal to a modulating input or having an inoperable configuration. maxDNA Configuration Tools also allow the import and export of point databases on either a system or DPU basis. During the engineering phase, the I/O database is typically distributed to individual DPUs for security reasons. The database assigned to a given DPU can then be accessed and connected to the control and data acquisition strategies being developed for that DPU.
In the plant the individual DPU databases can likewise be converted to other formats such as Access™ for use by plant or headquarters personnel. Once configured and enabled in the DPU, the loop configuration can be accessed from any system maxSTATION and displayed on the CRT. This display provides all process information in real time updated on the screen every second. Values are displayed in engineering units or percentages as configured for that particular variable. Logic signals are color coded for true or false.
Four levels of quality coding (good, bad, doubtful, and substitute) are provided for each process signal and are propagated through out the control strategy. In addition to normal logic overrides, individual algorithms can be configured to execute desired strategies upon detection of undesired quality codes associated with the input signals to that algorithm. Figure 2 – Detailed Representation of a Strategy Hierarchical Structure maxDNA Configuration Tools support a hierarchical organization of control objects.
This arrangement allows for: * Cut and paste of a branch of the hierarchy to replicate the configuration for a piece of equipment * Aggregate alarming – automatically created alarm statistics such as the number of high severity unacknowledged alarms in a branch of the control hierarchy to animate graphics displays * Group Alarm Acknowledge – single keystroke to acknowledge alarms in a branch of the hierarchy * Incremental Reload – incremental changes with NO effect on other branches * Inherited Characteristics – such as execution order and rate can be set for each branch
Virtual and Real DPU DPUs can be emulated in any maxSTATION to facilitate debugging and testing. Multiple engineers can work with different portions of the project in parallel without impacting each other’s work. The output of each engineer can then be combined and tested using the capabilities of the virtual DPU. Composite objects maxDNA Configuration Tools support the creation of custom control objects. A custom control object can be a loose collection of control blocks in a group, or can be a fully tested template.
Some features of composite object management include: * Controlled exposure of key parameters – the engineer can expose at the composite block level attributes of blocks used to make up the object * Controlled security of exposed parameters – the engineer can specify the security level necessary to manipulate individual parameters * User designated names for parameters – In01 of an AND gate can become Oil Pressure Ok * Locking – objects can be locked to prevent tampering * Copy and paste – composite objects can be cut and pasted to speed configuration Documentation
Complete documentation of the DPU configuration is contained in the DPU. This information can be accessed via the maxNET highway and viewed live or uploaded to any engineer’s maxSTATION on the system. In the maxSTATION, the configuration can be captured as a Windows Metafile Graphic in a “ . wmf” format which can be viewed by Autocad or Microsoft word. From the maxSTATION the configuration can be copied to a CD, printed via the system printer, or accessed by the corporate engineering office. A differences program allows the comparison of DPU configurations at several levels to insure complete integrity of the program.
All discrepancies are tabulated for review and action. On-Line DPU Interface In an on-line system, the DPU program can be modified at the following incremental levels – individual variable, individual loop, branches of the control hierarchy, or the entire DPU. This allows incremental changes enhancing the integrity of the entire modification process by not requiring complete DPU downloads for only small changes. The existing configuration is uploaded to the engineer’s maxSTATION. From here the configuration is modified as necessary and then downloaded to the DPU. In most system architectures, the DPUs used for control are redundant.
One of the DPUs is kept as active, controlling the process, while the other is set to the inactive mode. The revised strategy is downloaded to the inactive DPU. Once downloaded, the inactive DPU is activated and control is transferred to it. By utilizing the freeze and unfreeze instructions, each individual output whether modulating or binary can be compared with the state or value of the field device and unfrozen if compatible or investigated if uncompatible. In all cases the DPU with the original or old strategy is now the backup and can take over control if there are any problems with the new strategy.
If the new configuration is w
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