RU2801447C1 - Vibrating screen drive system control method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used to control the drive system of a drilling vibrating screen with a linear or elliptical trajectory of frame oscillations. The method for determining the phase shift for controlling the vibrating screen drive system of two unbalanced exciters rotating in different directions includes a constant measurement of the rotation time of one of the eccentric weights and the time interval between the moments of the eccentric weights passing through the positions in which the sensors are installed, fixed on the casings of the eccentric weight exciters. The installation angles of the eccentric weight position sensors are periodically measured between the horizontal positive semi-axis and the straight lines passing through the center of rotation of these eccentric weights and sensors. The time interval between the moments of passage of the position sensor by the eccentric weights, in which the sensors are installed, is measured from the moment of passage of the position sensor by an eccentric weight, rotating counterclockwise, until the moment of time of the passage of the position sensor by another eccentric weight, and the phase shift is calculated by mathematical dependence.

EFFECT: ensuring high throughput of the vibrating sieve due to increased accuracy in maintaining the design trajectory of movement of the points of the vibrating frame.

1 cl, 9 dwg

Description

The invention relates primarily to the oil and gas industry and can be used to control the drive system of a drilling vibrating screen with a linear or elliptical trajectory of frame oscillations.

The closest to the claimed method is a method of controlling the vibrating sieve drive system (Pat. RF No. 2402387) consists of two unbalanced exciters, including changing the phase shift between the unbalance rotation angles by acting on the electric motors of the unbalanced exciters, in which the rotation time of the first unbalance and the time interval are constantly measured between the moments of passage of the same positions by the unbalances, then the phase shift between the angles of rotation of the first and second unbalances is calculated.

The disadvantage of this method is the presence of a systematic error in measuring the phase shift between the angles of rotation of the rotors of the unbalance vibration exciters, which leads to a change in the trajectory of the points of the vibrating screen frame from the design one, and therefore reduces the throughput of the vibrating screen. The reason for this is the uncertainty between the time points of passing the sensors of which unbalances the time interval should be measured. Secondly, the unbalance position sensors are inaccurately located on the horizontal positive semi-axes passing through the centers of rotation of these unbalances, which also gives a systematic error in measuring the phase shift between the angles of rotation of their rotors.

The objective of the invention is to eliminate the systematic measurement error in measuring the phase shift between the angles of rotation of the rotors of unbalanced vibration exciters, which will increase the accuracy of maintaining the design trajectory of the vibrating screen frame points, and therefore will constantly ensure the efficiency of drilling mud screening.

The technical result is to provide a high throughput of the vibrating sieve due to an increase in the accuracy of maintaining the design trajectory of movement of the points of the vibrating frame.

The technical result is achieved by the fact that the method for determining the phase shift for controlling the system of vibrating screen drives from two unbalanced exciters rotating in different directions, including the constant measurement of the rotation time of one of the unbalances and the time interval between the moments of passage of the unbalances of the positions in which the sensors are mounted, fixed on casings of unbalance exciters, characterized in that they periodically measure the installation angles of the position sensors of the unbalances between the horizontal positive semi-axis and the straight lines passing through the center of rotation of these unbalances and sensors, and the time interval between the moments of passage of the unbalances of the positions in which the sensors are installed is measured from the time of passage position sensor by an unbalance rotating counterclockwise until the moment of passage of the position sensor by another unbalance, and the phase shift is calculated by the formula

where: Δt _about - the time of a full revolution of the unbalance rotating clockwise, s;

Δt _different - the time interval from the moment of passage of the unbalance, rotating counterclockwise, of its sensor until the time of passage of another unbalance of its sensor, s;

β ₁ , β ₂ - installation angles of the sensors relative to the horizontal, radians.

The vibrating sieve in figure 1 can effectively work only if there is self-synchronization of the rotations of the unbalance rotors, which rotate in different directions and their rotation angles ϕ ₁ (t), ϕ ₁ (t) are described by the formulas ϕ ₁ (t)=σ ₁ ⋅(ω _r ⋅t) and ϕ ₂ (t)=σ ₂ ⋅(ω _r ⋅t+α) (see the book Blekhman I.I. Synchronization of mechanical systems. - M.: Nauka, 1971), where t is the current time; ω _r - angular frequency of rotation of the rotors of unbalances 1 and 2; σ ₁ , σ ₂ - indices of the directions of rotation of the rotors of unbalances (as is customary in mathematics: σ _i =+1 counterclockwise rotation, σ _i =-1 clockwise rotation) and σ ₁ =-σ ₂ ; α - phase shift between the angles of rotation of the unbalance rotors. The figure 1 shows the position sensors of unbalances 1 and 3, as well as the marks of the midpoints of unbalances 2 and 4.

The phase shift between the angles of rotation of the rotors of unbalances according to this theory is determined by the formula:

where δ ₁ , δ ₂ - guiding angles of the centers of rotation of the rotors of the unbalances O ₁ and O ₂ relative to the center of gravity of the shaker frame assembly O; ΔM ₁ - excess torque of the asynchronous electric motor (HELL) of the 1st unbalance vibration exciter (DBV); vibrating moment of the vibrating screen, which is determined by the design parameters of the vibrating screen. The excess moment is equal to the difference between the electric motor moment of the IM and the moment of resistance on its rotor. During operation, it changes in an unknown way, therefore, when designing a vibrating screen, it is taken equal to zero and the design value of the phase shift is equal to α _P =σ ₂ ⋅(δ ₁ +δ ₂ ). In the prototype, the current value of α _and (7) is maintained equal to the design value α _P automatic control system.

The numbering of the DBV in figure 1 is arbitrary. Since the unbalance rotation angles have different signs, the phase shift between them is physically equal to their sum

As can be seen from formula (3), physically the phase shift does not depend on either the numbering of the WBVs or on the directions of their rotations, which is shown in figures 2-5. When the middle of one of the unbalance passes through the horizontal positive semi-axis i.e. ϕ _i (t _k )=0, then the middle of another unbalance at this time is rotated by an angle ϕ _j (t _k )=α _Ф .

Indirect measurement of the phase shift through the measurement of the time interval between the moments of passage of the middle of the unbalances of their position sensors has 2 options, as shown in figures 6 and 7.

In the first variant, the time interval is measured between the counterclockwise rotating WBV and the clockwise rotating WBV. If the first middle of the first unbalance is in the position of its sensor, then the second unbalance before the operation of its position sensor must pass, as shown in figure 6, the angle α _F , which corresponds to the time interval Δt _diff =α _F /(2⋅π/Δt _about ), where ω _r =2⋅π/Δt _about essentially the angular frequency of rotation of the rotors of the DBV. Then the measured value of the phase shift is equal to its physical value

According to the second variant, the time interval is measured between the WBV rotating clockwise and the WBV rotating counterclockwise. If the middle of the first unbalance is in the position of its sensor, then the second unbalance before the operation of its position sensor must pass, as shown in figure 7, the angle 2⋅π⋅α _F , which corresponds to the time interval Δt _different =(2⋅π-α _F )/( 2⋅π/Δt _about ). Then, in order for the measured value of the phase shift to be equal to its physical value, it must be determined by the formula

Since the first option is simpler, this option is used in the proposed technical solution.

DBV is manufactured on the basis of a special asynchronous electric motor of explosion-proof execution on legs. The unbalance casings are rigidly attached to the body of the DBV. The unbalance position sensor can be located on its casing on a horizontal positive semi-axis passing through the center of rotation. When mounting the WDM on a vibrating screen, the position sensor is displaced relative to the horizontal positive semi-axis, as shown in figures 8 and 9. In the case of mounting both WDMs on the same traverse, as shown in figure 8, the position sensors are displaced by the same angles β ₁ =β ₂ . When mounting the DBV on separate traverses, as shown in figure 9, the displacement of the position sensors can occur at different angles β ₁ , β ₂ . In addition, deformation of the shaker frame suspension springs can also contribute to these angles.

The displacement of the mass position sensors relative to the horizontal positive semi-axis leads to a systematic error in measuring the phase shift between the rotation angles of the mass rotors. Figures 8 and 9 show the displacement of the unbalance position sensors by angles β ₁ , β ₂ , which periodically need to be measured about once a month. The time interval between the pulses of the position sensors of the 1st and 2nd unbalances in this case will become different at the same value of the phase shift. The position sensor of the 1st WBV in figure 8 will give an impulse later than at zero value of β ₁ by the value of β ₁ /ω. The position sensor of the 2nd DBV will give an impulse earlier than at zero value of β ₂ by the value of β ₂ /ω _r . Then the time interval between these pulses will be equal to:

Hence, the measured value of the phase shift between the angles of rotation of the unbalances is:

The proposed technical solution has been tested on a physical model of the vibrating sieve. KTIR06111S slotted optoelectronic microcircuits were used as unbalance position sensors. The signal processing of the position sensors and the calculation of the phase shift between the angles of rotation was carried out by a measuring voltage converter E20-10 manufactured by L-Card.

Claims (5)

A method for determining the phase shift for controlling a system of vibrating screen drives from two unbalanced exciters rotating in different directions, including a constant measurement of the rotation time of one of the unbalances and the time interval between the moments of passage of the unbalance positions in which the sensors are installed, fixed on the casings of the unbalanced exciters, characterized in that that periodically measure the installation angles of the position sensors of the unbalances between the horizontal positive semi-axis and the straight lines passing through the center of rotation of these unbalances and sensors, and the time interval between the moments of passage of the unbalances of the positions in which the sensors are installed is measured from the moment of passage of the position sensor by the unbalance rotating against clockwise, until the time of passage of the position sensor by another unbalance, and the phase shift is calculated by the formula where: Δt _about - the time of a full revolution of the unbalance rotating clockwise, s; Δt _different - the time interval from the moment of passage of the unbalance, rotating counterclockwise, of its sensor until the time of passage of another unbalance of its sensor, s; β ₁ , β ₂ - installation angles of the sensors relative to the horizontal, radians.

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