SU1000504A1 - Method and apparatus for automatic control of defibring temperature - Google Patents

Description

(54) AUTOMATIC REGULATION METHOD

DEFIBRATION TEMPERATURES AND DEVICE

FOR ITS IMPLEMENTATION

one

The invention relates to the automatic control of technological processes in the pulp and paper industry and directly relates to the automatic control of the temperature of pulp in the pulp bath.

There is a known method of automatically controlling the temperature of the defibration by measuring the power consumed by the main electric drive of the fiberglass, converting it into a signal proportional to the actual temperature in the bath, comparing it with a signal proportional to a given temperature, and subsequently amplifying the error signal I.

A device for automatically controlling the temperature of the defibration is known, comprising a serially connected main engine of the finibber, a static power converter, a signal conversion unit, a comparison unit, a power amplifier, a servo drive, a control valve and a temperature setting unit 1, the circulating water pipeline 1.

However, as a result of the impact on the flow rate of the circulating water entering the drops of the ground stone, at a constant feed rate of the balance, the concentration of wood pulp in the fiber feed bath changes and, therefore, its quality indicators are not stable. At 5, the reduction of the supply of circulating water to the showers increases the enveloping of the working surface of the stone with wood pulp, which is equivalent to its blunting. This leads to an additional deviation from the required quality indicators of wood

10 masses.

The purpose of the invention is to increase the stability of the quality indicators of wood pulp while maintaining a constant defibration rate.

This goal is achieved in that according to the method of automatically adjusting the temperature of the defibration by measuring the power consumed by the main electric drive of the fiberglass, transforming it into a signal proportional to the actual temperature in the bath, compared to the signal proportional to the specified temperature, and then amplifying the error signal, amplified

an electrical signal proportional to the misalignment of the actual and set defibration temperatures is converted into a signal that changes the temperature of the circulating water supplied to the shoots of the ground stone, at a constant flow rate.

A device for automatic adjustment of the temperature of the defibration, containing the main engine of the microfibre in series, a power converter, a signal conversion unit, a comparison unit, a power amplifier, a servo drive, a control valve and a temperature setting unit, a circulating water pipeline, connected to the comparator unit, connected to a steam pipe and a circulating water pipeline, and a control valve is installed on the steam line.

The drawing shows a device for carrying out the method.

The device contains the main motor of the pulper 1, a power converter 2, a signal conversion unit 3, a comparison unit 4, a power amplifier 5, a servo drive 6, a control valve 7, a temperature setting unit 8, a pipeline 9 for recycled water, a heat exchanger 10, a steam pipe 11.

The method of automatic adjustment of the temperature of the defibration is carried out as follows.

Using the current transformers and voltages installed in the stator circuit of the main motor of the pulper, the power consumed from the network for defibration is measured. The output signals of these transformers are fed to the input of the power converter 2. This converter converts the input signal into a DC voltage proportional to the active component of the power consumed from the network by the main motor of the cooler. The output signal of the static power converter is fed to the input of the unit 3, which converts a voltage proportional to the active power of the engine of the cooler to a voltage proportional to the actual temperature of the pulp in the cooler bath. This output voltage is applied to the signal comparison unit 4, where the voltage U2, proportional to the actual temperature of the pulp, is compared with the output voltage Uj of the temperature setting unit, proportional to the given temperature of the pulp, equal to the plasticization temperature of lignin.

When the actual temperature of the wood pulp deviates from the setpoint, the error signal is 1) 4 Us - which is fed to the input of the power amplifier 5. The amplified mismatch signal Ug is fed to the servo 6 electric motor. Depending on the polarity

mismatch voltage U4 (respectively, and Uj) the servo motor 6 opens or regulates the control valve 7. This valve is installed on the steam line 11 and with its help

regulate the flow of steam supplied to the heat exchanger 10.

Through the heat exchanger lay pipeline recycled water. At a constant flow rate, this water is supplied under pressure to sprinkles of the ground som.

Depending on the position of the control valve 7, the steam supply to the heat exchanger 10 is reduced or increased, thereby reducing or increasing the temperature of the circulating water supplied to

stone spillage, with its constant flow rate. This ensures the automatic regulation of the temperature of the defibration, while maintaining the concentration of wood pulp undifferentiated, since the flow rate of circulating water is constant. Constancy of concentration provides an increase in the stability of the quality indicators of pulp.

The device for automatic adjustment of the temperature of the defibration works as follows.

Consider the initial steady-state temperature in the cooler bath as the source. In this case, the actual temperature of the wood pulp in the bath is equal to the preset, i.e., the plasticization temperature of lignin, and the stresses L and U-. are equal. At the same time, the control signal rassog / ;;) the match C} is equal to zero. Then the signal L. at the output of the power amplifier is also zero. This ensures that the servomotor 6 is stationary. In this case, the control valve 7 on the steam line 11 is in such a position that it provides such a steam flow that is necessary to heat the circulating water in the heat exchanger 10 to the plasticization temperature of lignin. Circulating water from the heat exchanger is fed to the drops of the grinder, creating the desired temperature in the bath. Assume that the temperature of the wood pulp in the bath has increased, this is caused by an increase in the load of the main engine

grinder. The latter will cause an increase in the output signal of the current transformer in the motor stator circuit and, accordingly, an increase in the voltage U at the output of block 2 and Uj at the output of block 3. Then, the control signal U4 from zero will be fed to the input of power amplifier 5, the output signal Uc, which is fed on the electric motor of the servo drive 6. The actuator mechanism of the servo drive closes the control valve 7 on the steam line 11 and accordingly reduces the flow of steam entering the heat exchanger 10 to heat the circulating water. Those samygu reduce. circulating water temperature

coming from the heat exchanger for sprinkling stone grinder, but its consumption is provided unchanged. As a result, the temperature in the cooler bath is restored to a predetermined value, and the mass concentration is not changed, i.e., the quality of the pulp remains unchanged.

Consider the operation of the device while reducing the actual temperature of the defibration from the set. The latter occurs at a decrease in the load of the main engine of the crusher, which corresponds to a decrease in the power consumed from the network. This leads to a decrease in the output signal of the current transformer in the stator circuit of the main motor and, accordingly, to a decrease in the voltage C at the output of the static power converter and U2 at the output of unit 3. At the same time, voltage U2 is obtained proportional to the actual pulp temperature less than voltage Uj, proporional set temperature defibration. The latter provide a positive error signal U Uj - Tsg, which serves as the input of the power amplifier 5, and after amplification, it is fed to the input of the electric motor of the servo drive 6.

As a result, the servo actuator opens the control valve 7 on the steam line 11 and consequently increases the temperature of the circulating water, which is fed to the drops of the ground stone, but the flow rate is kept constant. Thus, the temperature in the softer bath is restored to a predetermined value (lignin plasticization temperature) at a constant concentration of wood pulp, i.e., its quality remains unchanged.

When the actual mass temperature reaches a predetermined value, the error signal U4 goes to zero, thereby ensuring that the electric motor of the servo drive 6 is stationary. At that, the control valve 7 is set to a position that creates steam flow in the heat exchanger necessary to heat the circulating water to the required value.

Claims (2)

1. A method of automatically adjusting the temperature of the defibration by measuring the power consumed by the main electric drive of the defibr, converting it into a signal proportional to the actual temperature in the bath, comparing it with a signal proportional to the set temperature, and the subsequent amplification of the error signal, characterized in that, in order to increase the stability of the pulp quality indicators, the amplified electrical signal is proportional to the actual and The set defibration temperature is converted into a signal that changes the temperature of the circulating water supplied to the drops of the ground stone, at a constant flow rate. 2. A device for automatic adjustment of the temperature of the defibration, containing serially connected the main engine of the cooler, the power converter, the signal conversion unit, the comparison unit, the power amplifier, a servo drive, a control valve and a temperature setting unit connected to a comparison unit, a circulating water pipeline, characterized in that it has a heat exchanger connected to the steam pipe and a circulating water pipeline, and a control valve is installed on the steam pipe. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 403794, cl. D 21 1/04, 1974. Gy h turnaround water o Par 3)