CONTROL SYSTEM OF HIGH PRESSURE PARAOSCILLATORS
“RVSA”, Ltd factory develops a universal control system Boiler units of drum-type
type. The system is builted with use of the equipment and Devices of manufacture of
firms "Siemens", “АBВ”, “JUMO”, “Moeller”, resources which allow to solve almost all
problems connected with automation, protection and the signalling system of a process
of a steam production.
The control system is divided on two subsystems:
- ctually the boiler unit with a dust feeding system.
- Coal pulverisation with a feeding system of crude coal.
The automatic control system carries out following functions:
- Visualisation of processes of the boiler unit by means of SCADA systems with Software Simatic WinCC.
- Automatics of protection.
- Regulatings of key parametres of a steam production and a coal dust.
- Emergency and the warning.
The general block diagramme of system of automation is resulted on picture 1.
Two control units (regulating and protection) accept discrete and continuous
signals from sensing transducers and secondary devices of measures. On the gained
Informations control units perform logic and mathematical operations of machining the
accepted information on the put in pawn algorithms managing directors also give out
and signalling commands on power units and visualisation panels.
Visualisation of processes
is provided by means of two panels of operators (LCD the monitor and TR-
177V). Installation of the third panel separately for system is possible protection
On the monitor it is represented scheme with animation on which it is possible to
trace work of mechanisms of a copper, the basic technological parametres and as are
inferred text messages precautionary and the fault signalling. Representations take places in several windows:
- a copper, (picture No2)
- system of coal pulverisation, (picture No3)
- regulators, (picture No4)
- messages, (picture No2) and etc.
Picture No2. The copper circuit design
Picture No3. The circuit design of system of preparation of a dust
System of visualisation besides representation of key parametres arriving directly
from sensing transducers of physical quantities such as: pressure, temperature, level,
the charge, rule of final control elements and токовые loadings electric motors, makes
as calculation of thermal productivity of a copper, fuel rate and a specific fuel rate on 1 Gcal.
For calculation of thermal productivity of a copper calculation formulas are used
antalpii waters and pair, resulted in recommendations MI 2412-97 and MI 2451-98
VNIIM of D.I.Mendeleyev, accuracy of calculation is not worse than 0,5 %. Calculation
of the expense of fuel (A coal dust) it is made on speed of rotation and quantity of the
working feeders according to their adjusting characteristics.
On scheme in the form of pictogrammes the operating mode of the executive is displayed The mechanism - manual or automatic.
On all screens messages are on the right side deduced. Again appeared
message blinks, while it not blinker. A signal on which has occurred emergency stop, it
is marked by a shone point in the field of the message. The disconnected protection is
marked grey field of the message, corresponding signal.
Automatics of protection
provides a copper automatic stop in critical modes
when this or that parametre exceeds admissible size on to conditions of safety of
process, or the developed situation can lead to destruction of the equipment or
ecological accident. Work of emergency system is accompanied by the sound and light
alarm system, a conclusion of text messages to the basic and duplicating panels of
operators. The system fixes the original cause which has caused an emergency. All
events are fixed in a window of messages in chronometric sequence with the direction
of a concrete time of their origination, receipting and disappearrance. Algorithms of work
automatics are realised in the programmed controller
specially intended for this purpose, and having a food from two independent sources
(~220V and =220V) with UPS. The control unit противоаварийной automatics can be
completed, instead of luminous panels, own display for representation of messages.
The analysis of a condition of a copper is defined on discrete signals of achievement of
marginal levels by the copper operation factors, arriving from secondary devices by
which the copper is equipped.
In addition signals of marginal levels arrive from the regulating control unit
Simatic S7 300
which processes signals of analogue sensing transducers, than it is provided duplicating of an alarm.
Regulating of technological parametres
is provided with the program of the second controller.
Automatic control key parametres:
- Water level in the boiler drum.
- Steam Temperature on an exit from a copper.
- Pressure in the boiler drum or/and a steam pressure in front of the turbine.
- The Discharge in a fire chamber.
- The Relationship fuel-air, or productivity - air.
- Loading of the coal crumber.
- Temperature of a mix of a dust and air.
All regulators process the arriving information from sensing transducers in a digital
form on in advance put in pawn algorithms. The signal from the level detector is
processed on special algorithm taking into account the changing density of water and
saturated steam (depending on pressure in the boiler drum). Ample opportunities of
Simatic S7 300
and its speed has allowed to build the interconnected
adaptive regulators reacting not only on deviations of parametre, but also on disturbing
affecting (the combined system of regulating with conducting and subordinated by
regulators of intermediate parametres or their derivatives). It allows to gain pinpoint
accuracy of maintenance of parametres at the set level at satisfactory dynamics
(stability, the minimum overcorrections, sweeping restoration).
The regulators affecting power units of directing apparatuses and regulating valves,
have knot of compensation of gaps of the mechanism of the drive. Besides, the drive of
valves and power units can be completed with the frequency drive that will allow to
provide exact and smooth regulating of parametres, to lower electric and mechanical
dynamic loads on the drive. Frequency are controlled the drive (FCD) it is possible to
operate on a network and to gain the information on speed and loadings. For locked
latches FCD will allow to retard speed at the approach to the closed rule and on the
moment (FCD gives out a moment signal) to disconnect the drive (reliable and safety
closing). The drive with FCD are less subject to breakages in a mechanical part of the
mechanism and propellers fail (highly reliable and a scram protection) less often. Thus it
is possible to represent more than the information on work of power units. The
bumpless transfer from hand control on an automatic regime and back is provided.
Regulating зumpings out and air supplies with dual system of flue-gas pumps and
ventilating fans provides uniform loading of propellers (a regulator division of loadings).
Besides, at emergency switching-off of one of propellers, second it is automatically
inferred on the maximum productivity (the greatest possible opening of the directing
apparatus on a condition current loadings) and then is connected to regulator, the
system defines necessity of automatic decrease in loading of a copper.
Was possiblly installation FCD for flue-gas pumps and ventilating fans that provides
regulating without use of directing apparatuses (very much a cow-hitch), smooth
dispersal without dynamic loads, decrease in a slump of voltage and starting currents at
start-up, that positively affects durability of electric motors. Regulating by means of turns
reduces loadings on the mechanism and increases service life of flue-gas pumps and
ventilating fans. In addition to stated all above the current consumption decreases and
The regulator of a relationship air - fuel has some modifications:
- With correction on O2
- On difference on the air heater
- On the measured active current
- On a full current, with active current scaling on propeller model
All regulators have system of capture of an operating point, it when in a manual
regime the machinist of a copper infers parametre on demanded value and then the
automatic regime is switched on, the system thus supports work in the chosen point.
The system allows to displace productivity of even and odd group of pulverised-coal
feeders, choosing optimum process of burning.
For air regulator the system of extreme regulating with an automatic search of an
operating point of a relationship air-fuel, providing the minimum specific fuel rate on
manufacture of one Gcal heat develops.
Loading of the crumber and temperature airdust mixes is controlled by change of
productivity to the DOG with the frequency drive and extent of opening of gates
- Current of the drive,
- Differential head on the crumber.
- Temperatures airdust mixes.
Work of the coal crumber is blocked with dust level in loading pockets for what level
detectors of radar type and sensing transducers of marginal levels of vibrating type are installed.
For each regulator there is a shield in visualisation system that allows to control
quality of work and to observe changes of parametres in dynamics on time schedules. Look picture No 4.
Picture No 4. Level regulator
Emergency and the warning has two channels:
- Basic - from system противоаварийной automatics.
- Additional - from the management control unit, providing the reserve channel of
the signalling system on a small board with a consecutive leading-out of the
information on emergencies and messages on the systems of protection disconnected at present.
Each emersion of the new message is fixed on the display with simultaneous light
and an audible signal. This condition remains before receipting performance. All
messages and events remain in archive and can be seen in a window of messages.
Look picture No 5.
Picture No 5. Window of messages
All operating equipment is protected from mechanical injuries and to dust
penetration for what filters and leakproof cabinets are provided. Hand control bodies
(buttons, keys of sampling of a regime have illumination) take places on benchboards
taking into account ergonomics and convenience demands Managements.
Cabinets with the switching equipment are equipped by safety keys, the
signalling system and protection against loss of a phase and incorrect phasing.
Partially this system has been realised in the course of repair-regenerative works
on a type copper - PC 10. A copper пылеугольный, drum-type, water trumpet, with the
vertical shields, consisting of the basic and prepowered drum, system of screen and connecting pipes.
Productivity - 230 t/hour., workers pressure in a drum - 109 атм., gaseous steam
temperature - fuel S.Szhiganie's 510 grades torch, copper configuration P-shaped. The
copper is riged by 8 pulverised-coal burners.
That attains accuracy of maintenance of a water level in the boiler drum in an
automatic regime +/-7 mm. Accuracy of maintenance of temperature on an entry in the
general collecting channel +/-100С, at an arrangement ыteam cooler before a prime of
the steam superheater and without the temperature control between the first and
second steps of the steam superheater because of absence of the sensing transducer,
i.e. most not favorable conditions for automatic control system.