SU1237253A1 - System for automatic regulation of dust preparation in mill - Google Patents

Description

The invention relates to the automatic regulation of dust-preparing installations of boiler units of thermal power plants and can be used to control the temperature of the drying agent behind the mill, grinding the explosion-hazardous coals.

The aim of the invention is to improve the quality of regulation.

FIG. I presents a block diagram of an automatic control system for a dust preparation plant; in fig. 2 - transient in the control system, obtained by mathematical modeling.

The automatic dust control system in the mill of FIG. l) consists of the cooling water supply regulator G, the input of which through the first adder 2 is connected to the sensor 3 and the setpoint 4 of the drying agent temperature behind the mill, and the output through the actuator 5 is connected to the valve 6 installed on the cooling water supply line to The drying agent inlet before the mill, the regulator 7 of the drying agent temperature behind the mill, the inlet of which through the second adder 8 is connected to the sensor 9 of the valve position 6 and through the nonlinear element 10 connected to the output of the first adder 2, and the output connected Res actuator 11 with the damper 12 mounted on the duct supplying the hot flue gases in the mill before drying agent,

The automatic regula- tion system of the dust preparation plant can be implemented on serially produced domestic equipment such as KASKAD, AKESR or RPIB.

When the temperature of the drying agent changes behind the mill (measured by sensor 3, the output signal of the first adder 2 generates a mismatch signal between the current temperature value and its setting (b) (setting unit 4).

de-1-in.

The signal is fed to the input of the controller, torus 1, which forms the PI-law of regulation and controls through the actuator 5 valve 6 on the cooling water supply line

in the gas duct drying agent; and before the mill,

If 9 0, then valve 6 opens and the supply of cooling water to the gas duct increases, which leads to a rapid decrease in temperature 5 to

V.

9 due to the low inertia of this control loop. Opening valve b will cause the appearance of the signal.

at the output of sensor 9 and, therefore, of the adder 8. The regulator .7, which is switched on according to the roi-law through the executive mechanism 11, will cover the sponge 12 on the flue supplying hot

gases in the gas duct of the drying agent in front of the mill, and reduce the total total amount of heat supplied to the mill so that the signal from the second summara 8 becomes zero, i.e.

valve 6- is closed by polio. This circuit acts with considerable inertia and will not introduce any disturbances into the operation of controller 1.

The nonlinear element 10 has the following output characteristic:

 . Gl9g P i O 2. D at a 02 0

If the valve 6 closes, if it was open, or remains closed, if it was closed, the signal from the output of sensor 9 will be zero, and the input of the regulator 7 through the non-linear element will receive a signal from the LH and through the actuator 11 will open the gate 12 to supply hot gases to the mill and the drying capacity of the system will increase

dust preparation,

An increase in the temperature of the drying agent behind the mill (b) is the most dangerous situation from the point of view of explosion safety, and this situation is eliminated by the high-speed regulator 1 of cooling water supply to the drying agent gas duct. In static conditions, the cooling water supply valve 6 is closed and heat of the boiler exhaust gases is used. Water injection into the gas duct of the drying agent in front of the mill operates only in transient conditions and does not allow the temperature of the drying agent to be behind the mill with deep fluctuations in the moisture content of the raw coal beyond the permitted limits.

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and, therefore, disabling the mill remedies.

The process of adjusting the temperature in the most severe emergency (disconnection of raw coal supply to the mill) is shown in FIG. 2

As can be seen from FIG. 2, the temperature deviation does not exceed 25% (9 106.25 ° C). With commonly used control schemes, such a disturbance leads to a deviation in the temperature of the drying agent behind the mill by an order of 757, (50 ° C, i.e., an emergency shutdown of the dustproof, protection system from hitting the protection response setting 120 s).

Thus, the proposed system provides for an increase in the quality of temperature control of drying 37253

agent behind the mill, which significantly increases the reliability and explosion hazard of the preparation plant, including in the most dangerous start-up and stopping mode.

In addition, the automatic control system of the dust preparation plant is simple during commissioning and is reliable in operation.

The economic effect consists of reducing the duration of just power units associated with violations of the start-up and shutdown modes and erroneous actions of personnel during the operation of dust preparation plants, reducing the cost of repairing the dust preparation plant.

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Editor M, Pandora

Compiled by V.Alekperov Tehred L.Oleinik

Order 3222/8 Circulation 582Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Design, U

Proofreader T. Kolb

Claims (1)

AUTOMATIC SYSTEM . REGULATING DUSTING IN MILL with a raw coal feeder and a mill fan that includes a Cooling Water supply regulator, the outlet of which is connected to the valve actuator installed on the cooling water supply line to the drying duct of the drying agent in front of the mill, the regulator of the drying agent temperature behind the mill installed on the flue duct, sensor and unit temperature of the drying agent behind the mill, connected to the corresponding inputs of the first adder, position sensor a valve installed on the cooling water supply line connected to the first inlet of the second adder, and a nonlinear element, which in order to improve the quality of regulation, the output of the first adder is connected via a nonlinear element with the second input of the second adder and with the input of the regulator cooling supply. water, and the output of the second adder is connected to the input of the temperature controller of the drying agent behind the mill · 8Ts „„ 1237253 > 1237253 one