When not under conditions "ash ash monitor using closed-loop control" is selected from the non-volatile coal jigging sorting low ash coal, coal is coal selected changes affect the stability of the coal ash important source of disturbance. Due to the limitations of the on-site jig discharge and dewatering and lifting capacity, as well as the operational requirements for the stabilization of clean coal ash, the efficiency of the jig, and the processing capacity of raw coal, people are increasingly aware of: "Single automatic discharge control "It is difficult to adapt to the above production needs. In this regard, this paper proposes a new method of “automatic coal feeding according to the original coal quality control” (referred to as “coal coal feeding”): “Controlling the amount of coal according to the thickness of the heavy material layer in the first and second stages of the jig” to form the coal. Automatic control mode combined with discharge. The continuous application of the site at the Tiger Tailing Coal Preparation Plant in the past two years proves that the new technology is feasible and the above problems have been alleviated or resolved.

2 Site conditions

The jigging workshop of the Tiger Taiyuan Coal Preparation Plant adopts the main, re-, and three-selection process, 3 main washing jigs, 1 re-washing, and 1 three-washing, all of which are SKT93-14 jigs. It is 3.0Mt/a; the raw coal is selected as No. 2 gas coal, the particle size range is 60-0.5mm, and the vermiculite content is about 22%. The “coal coal supply” test is carried out on the main washing jig. The main washing machine produces ash from 5.51% to 6.00% of secondary clean coal, ±0.1 content is 12% to 18%, and the second stage of the jig is actually sorted. The density δP=1.31～1.35g/cm3; the inverter controls the reciprocating electric vibration to feed the coal; the functional block diagram of the automatic control system using the TKX-I type jig is shown in Fig. 1.

3 Leading arguments for “coal coal supply”

(1) From the point of view of the automatic control of the jig, the “change of raw coal quality” consists of two parts: one is the change of the proportion of “fine, medium and fine” of raw coal and the degree of viscosity of raw coal (including in fine coal) The change of water quantity causes; the other is the other factors of raw coal, such as the low-density content of raw coal and the influence of ash, particle size composition and muddy degree on the optimal sorting density of the second stage of the jig. After the implementation of “coal coal supply”, the influence of the proportion change of the raw coal and the change of the viscosity on the thickness stability of the first and second heavy material layers can be reduced from the perspective of coal feeding.

(2) The stability of clean coal ash is related to the thickness and stability of the two-stage heavy material layer. Due to the limitation of discharge capacity and dewatering and lifting capacity, it is necessary to keep the thickness of the two sections of heavy material layer stable, and it is necessary to match the coal feeding and discharging.

(3) In the jig, the raw coal is stratified by density under the reasonable combination of wind and water. At the same time, under the dynamic balance of coal feeding and discharging, the proportion of meteorite and medium coal in the raw coal changes and the raw coal The change in viscosity is dynamically reflected by the thickness of the first and second heavy material layers. Therefore, according to the thickness of the first and second heavy material layers of the jig, the amount of coal fed back can be controlled, which constitutes “automatic coal feeding according to the proportion change of the original coal quality”.

(4) The effect of low-density content of raw coal and its ash on the optimal sorting density of the second stage of the jig: 1 Under the condition of no closed-loop control of ash, the operator can base the raw coal in the jig. Operating status, clean coal fast ash, etc., coarse adjustment of the second section weight weight, fine adjustment of the two sets of industrial control machine to adjust the sorting density of the second buoy of the jig to track the best of the second section of the jig Sorting the density, forming a triple adjustment of coal, discharge, and operation coordination, and finally making the clean coal ash stable. 2 Under the condition of ash closed-loop control, after the operator adjusts the weight of the second section weight, the industrial computer automatically changes the set value of the two sections in the industrial computer according to the deviation value of the ash signal of the ash meter and the set ash. Finely adjust the sorting density of the second buoy of the jig to achieve the best sorting density, and form a closed-loop control of ash, forming a three-fold closed-loop adjustment of coal, discharge and ash, and finally stabilize the clean coal ash.

4 Implementation method of “coal coal supply”

In the industrial computer, the two functional blocks of “coal coal feed” and “automatic discharge” jointly analyze and determine the thickness of the first and second heavy material layers (Fig. 1). The “coal to coal” function block converts the corresponding decision result into an analog signal output and controls automatic coal feeding.

4.1 Parking status

In the parking state, the industrial control machine stops feeding coal and discharging materials, and establishes a parking status indicator in the program to prepare for getting started.

4.2 Starting condition

When the start/stop button is pressed, the industrial computer starts to supply coal. At this time, the amount of coal to be controlled should be close to the normal coal supply value. Starting delay - After forming the first and second stages, it enters the normal adjustment state.

4.3 Work adjustment status

In the work adjustment state, according to the thickness of the first and second heavy material layers of the jig, the large, medium and small step increase/decrease, timing interval and high and low limit are comprehensively adjusted.

4.3.1 Relationship between the first and second paragraphs

For the adjustment of coal supply, it is necessary to take into account the thickness of the heavy material layer of the first and second sections. The basic principle is: 1 as long as the two have more than the respective upper limit action band, the coal reduction; 2 only both are lower than the respective lower limit action band, the coal increase; 3 either or both, neither High, not lower than the upper and lower limit action belts, the amount of coal is unchanged.

4.3.2 Timing interval

The time interval is the interval between two automatic coal feed adjustments. From the issuance of the electronic control signal of the coal to the formation of the first and second beds and the thickness of the heavy material layer, there is a great lag, which is the main factor determining the long and short timing interval. At the Tiger Tailing Coal Preparation Plant, the timing interval for the increase and decrease detection is 13s.

4.3.3 Upper and lower limit action bands and adjustment steps

The setting of the upper and lower limit action bands is related to the jig discharge control algorithm. Here is a "polyline PID" algorithm similar to the slash control. The discharge control function is implemented above the "set value", that is, the thickness of the heavy material layer is controlled above the set value. Make multiple action bands for the first and second segments.

At the "timing interval" point, the increase/decrease adjustment step varies with the thickness of the measured heavy material layer: 1 when the thickness of the measured heavy material layer is less than 1, the amount of coal feed is increased; 2 when the thickness of the measured heavy material layer is Between 1 and 2, the amount of coal to be added is small; 3 when the thickness of the measured heavy material layer is between 2 and 3 in the non-increasing/decrease working area, the amount of coal is constant; 4 when the thickness of the measured heavy material layer is Between 3 and 4, the amount of coal to be reduced is small; 5 when the thickness of the measured heavy material layer is between 4 and 5, the amount of coal is reduced; 6 when the thickness of the measured heavy material layer is greater than 5, the amount of coal is large Decrease.

In Figure 2, the width of the non-increasing/decrease working area is wider than that set in other control areas, which plays an important role in stabilizing and preventing oscillation of the coal regulating system; the position of the multiple action bands of the heavy material layer is relatively Fixed above the “set value”, not only related to the “polyline PID” algorithm of the jig discharge control, but more importantly, the “multi-action band of the heavy material layer moves with the change of the set value”. The characteristics are consistent with the needs of field control adjustment.

When applied, the relationship between the action band, the adjustment step size and the first and second segments should be controlled after comprehensive decision-making.

4.3.4 High and low limit

The high and low limit of automatic coal feeding limits the scope of coal feeding control. Due to the changing working conditions on the site, the high and low limit of the coal supply is manually adjustable, which is set by the operator according to the actual needs of the site.

4.4 Parking process

Two parking modes are set: manual parking and automatic parking. When the start/stop button is pressed in the non-stop state, it is manual stop, and the industrial control machine stops feeding and discharging. In the running process, once the thickness of the heavy material layer of the first and second sections of the jig is lower than the respective set values, the industrial control machine enters the automatic parking process: if this state can be maintained for 28s, it will automatically stop; When the conditions of the automatic parking process are destroyed during this time, the industrial computer automatically returns to the work adjustment state.

5 "Coal quality coal supply" operation effect

The continuous operation of the site in the past two years was carried out under the condition that the closed-loop control of ash was not realized. The application rate of “coal coal supply” was close to 100%, and it showed five significant effects:

(1) The jig has the adaptability to the change of the original coal quality. The proportion of coal quality and the degree of viscosity of the coal in the Laotaitai Coal Preparation Plant accounted for about 70% of the change of the original coal quality. The other factors of the original coal quality accounted for about 30% of the optimum sorting density of the second stage of the jig. . Therefore, the use of "coal to coal" can make the adaptability of the jig to the original coal quality change of about 70%.

(2) The thickness of the second-stage heavy material layer is stable in the corresponding “non-increasing/decrease working area of ​​the action belt”, which lays a foundation for the stability of the clean coal ash.

(3) Cooperating with automatic discharge, effectively alleviating the contradiction between “maintaining clean coal ash stability and increasing raw coal treatment volume” encountered in sorting low-ash clean coal under non-easy coal preparation conditions, so that the treatment amount is based on raw coal. The change of coal quality ratio is automatically adjusted reasonably, and the purpose of automatic coal feeding control according to the maximum load of the first and second stage discharge buckets is indirectly achieved.

(4) The improvement of the degree of automation of the jig, the operation of the workers is simplified, the working state of the jig is improved, and the quantity efficiency is improved.

(5) Effectively solve the problem that the buoy is laminated by heavy materials, and improve the reliability of the inspection system.

6 Technical inspection results

Through the on-site single-machine inspection, it is proved that the quantity efficiency of the jig can be realized after the automatic discharge and automatic coal feeding, compared with the original manual control of coal feeding and discharging, under the current coal quality conditions of the Tiger Tailing Coal Preparation Plant. Increase by 6%.

Conclusion

Although this report introduces in detail the new technology of automatic coal feeding for the jig in Fushun Coal Preparation Plant, this technology greatly improves the economic benefits and output of Fushun Coal Washing Plant. I hope that the majority of coal washing plants will make full use of the new coal-feeding technology of the Fushun Coal Washing Plant Jig to help the coal washing factories around the city to meet the difficulties and situation of the current coal washing industry.

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