A coal mechanical sampling device sampling system performance optimization device and method

Abstract

The application discloses a coal mechanical sampling device sampling system performance optimization device and method, wherein a coal flow shaper and two cross-belt dividers are additionally arranged on a dividing feeding belt of the mechanical sampling device, the running tracks of the two cross-belt dividers are arranged at an angle of 45 degrees with the center line of the dividing feeding belt, and the running tracks of the two cross-belt dividers are arranged at an angle of 90 degrees. The application avoids the situation that a certain section of the coal sample cannot be taken due to short or less coal flow, and improves the representativeness of the dividing and sampling. Compared with the unshaped coal pile, the thickness of which exceeds the applicable range of the divider, the cutting sample is scattered and lacks completeness, the coal flow is shaped by the coal flow shaper, the thickness of the coal flow is within the applicable range of the divider, the coal flow is relatively uniform, and the obtained cutting and sampling is more representative. The coal flow shaper and the cross-belt divider are additionally arranged on the dividing feeding belt, the scheme is reasonable, the structure is simple, the technology is mature, the implementation is easy, and the precision and accuracy of the dividing are effectively improved.

Description

Technical Field

[0001] This invention belongs to the technical field of thermal power plants and relates to a performance optimization device and method for a coal mechanical sampling and preparation system. Background Technology

[0002] In my country, thermal power plants have largely implemented mechanical coal sampling and preparation devices in the sampling stages of incoming coal and coal fed into the furnace. This not only reduces manual labor intensity and shortens the sampling cycle, but also primarily eliminates human intervention and improves fuel management. The basic structure of a mechanical coal sampling and preparation device consists of: a sampling system (primary sampler and its drive system), a sample preparation system (feeder, crusher, and divider), a sample collector, a waste coal (surplus coal) return device, and an electrical control system. The main working principle is as follows: the primary sampler takes a certain amount of coal sample (primary subsample), which is fed into the crusher for crushing. After crushing, the sample is cut and reduced by the divider. The cut sample enters the sample collector, while the remaining undivided sample enters the waste sample return device. Thus, a single primary subsample is prepared into a sample and enters the sample collector, completing the sampling and preparation of one primary subsample. This process continues until the sampling and preparation of the entire batch of coal or the entire sampling unit is completed. Finally, the total sample (combined subsample sample) from the sample collector is sent to the sample preparation room for subsequent sample preparation and analysis. In the entire sampling and preparation process, sampling variance accounts for approximately 80% of the total variance. Therefore, the representativeness of the total sample taken by the mechanical sampling device directly determines the reliability of the sample results. The most crucial step in determining the representativeness of the total sample is the sample reduction stage.

[0003] Currently, the most commonly used type of sample divider in mechanical sampling devices is the cross-belt coal flow scraper divider and the falling coal flow divider (rotary cutting type, etc.). Technical requirements stipulate that after crushing, the sample should be cut at least 10 times before further reduction. However, while most thermal power plants' mechanical sampling devices are designed to cut 10 times, the effective number of cuts is often only 5 or 6, or as few as 1 or 2, or different quality coal segments are not cut within the reduction interval. Furthermore, to reduce production costs, thermal power plants purchase large quantities of low-quality coal, containing more difficult-to-crush particles such as gangue, significantly increasing the coal's heterogeneity and frequently resulting in insufficient reduction accuracy or reduction bias. Summary of the Invention

[0004] The purpose of this invention is to provide a method for optimizing the performance of a coal mechanical sampling device's sampling system. This method can solve problems such as poor representativeness of the sample reduction caused by uneven coal quality before and after the coal flow, thereby improving the representativeness of the sample produced by the mechanical sampling device and the level of fuel management in power plants.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A performance optimization device for a coal mechanical sampling device includes a coal flow shaper and two transverse belt dividers installed on the feed belt of the mechanical sampling device. The running trajectory of the transverse belt dividers is arranged at a 45° angle to the center line of the feed belt, and the running trajectories of the two transverse belt dividers are arranged at a 90° angle.

[0007] A further improvement of the present invention is that it includes a coal flow shaper, a shrinking feed belt, a first shrinker, a second shrinker, a first shrinking motor, a second shrinking motor and a PLC controller, a first sampling port, a second sampling port and a waste port.

[0008] The first and second shrink dividers are mounted on the shrink feed belt. The running trajectories of the first and second shrink dividers are arranged at a 45° angle to the centerline of the shrink feed belt, and at a 90° angle. The first shrink divider is connected to the first shrink motor, and the second shrink divider is connected to the second shrink motor. The first shrink divider has a first sampling port at its bottom, and the second shrink divider has a second sampling port at its bottom. There is a discharge port at one end of the shrink feed belt. The coal flow shaper, the shrink feed belt, the first shrink divider, the second shrink divider, the first shrink motor, and the second shrink motor are all connected to the PLC controller.

[0009] A further improvement of the present invention is that the opening size of the first divider and the second divider is not less than three times the nominal maximum particle size of the coal sample.

[0010] An optimization method for a coal mechanical sampling device sample preparation system performance optimization system as described above includes the following steps:

[0011] 1) The coal sample falls from the crusher outlet to the shrinking feed belt, which transports the coal sample and shapes it through the coal flow shaper.

[0012] 2) The first and second reducing motors start after the reducing feed belt starts running. The reducing feed belt runs to transport the coal sample to the second reducing device. The first and second reducing motors start at the same time, respectively driving the second reducing device and the first reducing device to cut the coal flow.

[0013] 3) The cut sample of the coal flow cut by the first reducer falls into the coal sample collection bucket through the first sampling port, and the cut sample of the coal flow cut by the second reducer falls into the coal sample collection bucket through the second sampling port.

[0014] 4) Coal streams that have not been cut by the first and second dividers enter the waste sample return device through the waste port.

[0015] A further improvement of the present invention is that the thickness of the coal sample after shaping does not exceed three times the nominal maximum particle size of the coal sample, and the width is less than the width of the feed belt for reducing the coal size.

[0016] A further improvement of the present invention is that the opening size of the first divider and the second divider is not less than three times the nominal maximum particle size of the coal sample.

[0017] A further improvement of this invention is that the time interval Δt between the first and second reducers is calculated using the following formula:

[0018]

[0019] Among them: W belt —Reduce the width of the feed belt;

[0020] ν belt —The running speed of the feed belt.

[0021] A further improvement of this invention is that the reduction ratio of the first reducer and the second reducer is calculated by the following formula:

[0022]

[0023] Among them: W belt —Reduce the bandwidth of the feed belt;

[0024] D—The opening size of the divider;

[0025] H 煤流 —Thickness of the coal flow on the feed belt;

[0026] ρ — density of coal flow on the feed conveyor belt;

[0027] m 留样 —The amount of sample retained after one operation of the reduction device; wherein, the reduction device is a reduction device including reduction unit 5 and reduction unit 6.

[0028] m 煤样 — The amount of coal sample reduced in one operation of the reduction device.

[0029] A further improvement of this invention lies in the sample retention volume per operation of the reduction device. D·H 煤流 ·ρ;

[0030] The amount of coal sample to be reduced in one operation of the reduction unit (m) 煤样 =2·W belt ·W belt ·H 煤流 ·ρ.

[0031] A further improvement of this invention lies in increasing the reduction ratio by adjusting the opening sizes of the first and second reduction units. The increased reduction ratio is calculated using the following formula:

[0032]

[0033] Where: D1—the opening size of the first divider;

[0034] D2—Second divider opening size;

[0035] W belt —Reduced feed belt width.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] Compared with the prior art, the present invention has the following technical effects:

[0038] This invention adds two coal dividers and a coal divider motor to the coal feeder belt, occupying little space and not affecting the normal operation of the sampling system. The cross-belt coal divider's running trajectory is arranged at a 45° angle to the coal feeder belt, which not only cuts the coal flow laterally but also ensures that coal samples from the front, middle, and rear sections of the entire coal flow are cut, avoiding the situation where a section of coal is not sampled due to a short or small coal flow, thus improving the representativeness of the coal sample. Compared with an unshaped coal pile, whose thickness exceeds the applicable range of the coal divider, resulting in sample spillage and incompleteness, the coal flow is shaped by the coal flow shaper, and the coal flow thickness is within the applicable range of the coal divider, resulting in a more uniform coal flow and more representative cut samples. The addition of a coal flow shaper and a cross-belt coal divider to the coal feeder belt is a reasonable solution with a simple structure, mature technology, and easy implementation, effectively improving the precision and accuracy of coal reduction. Attached Figure Description

[0039] Figure 1 This is a top view showing the arrangement of the first and second reducers in the system of the present invention.

[0040] Figure 2 This is a side view of the arrangement of the first and second reducers in the system of the present invention.

[0041] Figure 3 This is a schematic diagram of the operation of the first and second reducers in the system of the present invention;

[0042] Figure 4 This is a schematic diagram of the operating trajectories of the first and second reducers in the system of the present invention;

[0043] Figure 5 This is a schematic diagram showing the opening dimensions of the first and second dividers in the system of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings.

[0045] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0046] Following the above technical solutions, such as Figure 1 As shown, by adding a coal flow shaper 1 and two transverse belt dividers to the reducing feed belt 2 of the mechanical sampling device, the running trajectory of the transverse belt dividers is arranged at a 45° angle with the center line of the reducing feed belt 2, and the running trajectories of the two transverse belt dividers are arranged at a 90° angle, the problem of poor representativeness of the reducing sample caused by the uneven coal quality before and after the coal flow is solved, thereby improving the sample representativeness of the mechanical sampling device and the fuel management level of the power plant.

[0047] The mechanical sampling device in this invention is a device existing in the prior art.

[0048] For details, see Figure 1 and Figure 2 This invention discloses a performance optimization device and method for a coal mechanical sampling and preparation device. A coal flow shaper 1 and a cross-belt divider are installed on the reducing feed belt 2 of the coal mechanical sampling and preparation device. The device includes a coal flow shaper 1, a reducing feed belt 2, a first divider 5, a second divider 6, a first divider motor 3, a second divider motor 4, a PLC controller, a first sampling port 7, a second sampling port 8, and a waste port 9.

[0049] See Figure 4 and Figure 5 The first shrinker 5 and the second shrinker 6 are installed on the shrinking feed belt 2. The running trajectories of the first shrinker 5 and the second shrinker 6 are arranged at a 45° angle with the center line of the shrinking feed belt 2, and at a 90° angle. The first shrinker 5 is connected to the first shrinking motor 3, and the second shrinker 6 is connected to the second shrinking motor 4. The first shrinker 5 is provided with a first sampling port 7 at its bottom end, and the second shrinker 6 is provided with a second sampling port 8 at its bottom end. The shrinking feed belt 2 has a discharge port 9 at one end. The coal flow shaper 1, the shrinking feed belt 2, the first shrinker 5, the second shrinker 6, the first shrinking motor 3, and the second shrinking motor 4 are all connected to the PLC controller.

[0050] See Figure 3 The first sample inlet 7 is connected to the first drop tube 10, and the first drop tube 10 is connected to the coal sample collection bucket 12.

[0051] The second sampling port 8 is connected to the second drop pipe 11, and the second drop pipe 11 is connected to the coal sample collection bucket 12.

[0052] The present invention provides a method for optimizing the performance of a coal mechanical sampling device's sampling system, comprising the following steps:

[0053] (1) The coal sample falls from the outlet of the crusher to the reducing feed belt 2. The motor drives the belt of the reducing feed belt 2 to transport the coal sample. The coal sample is shaped into a shape with appropriate thickness and width (circular cross section) by the coal flow shaper 1. The thickness does not exceed three times the nominal maximum particle size of the coal sample, and the width is less than the width of the reducing feed belt 2. (1~2) cm is left on each side of the widest coal flow to prevent coal sample particles from rolling out of the reducing feed belt 2.

[0054] (2) The first reducing motor 3 and the second reducing motor 4 start after the reducing feed belt 2 runs. The reducing feed belt 2 runs and transports the coal sample to the second reducing device 6. The first reducing motor 3 and the second reducing motor 4 start at the same time, respectively driving the second reducing device 6 and the first reducing device 5 to run and cut the coal flow.

[0055] The opening size of the first reducer 5 and the second reducer 6 is not less than three times the nominal maximum particle size of the coal sample being reduced.

[0056] The operating time interval Δt(s) of the reducer is adjusted by the reducer motor controller:

[0057]

[0058] Among them: W belt — Width of the reduced feeder belt, in meters (m);

[0059] ν belt —The running speed of the feed belt, in meters per second (m / s).

[0060] (3) The cut sample of the coal flow cut by the first divider 5 falls into the coal sample collection bucket through the first sampling port 7, and the cut sample of the coal flow cut by the second divider 6 falls into the coal sample collection bucket through the second sampling port 8.

[0061] (4) Coal streams that have not been cut by the first divider 5 and the second divider 6 enter the waste sample return device through the waste port;

[0062] (5) Calculation and adjustment method of reduction ratio:

[0063] a) Calculation of reduction ratio:

[0064] Sample retention volume per cycle of the fraction reduction device:

[0065] The amount of coal sample reduced per operation of the reduction unit; m 煤样 =2·W belt ·W belt ·H 煤流 ·ρ

[0066] Reduction ratio:

[0067] Among them: W belt —The bandwidth of the reduced feed belt, in meters;

[0068] D—The opening size of the divider, in meters (m);

[0069] H 煤流 —Thickness of the coal flow on the feed belt;

[0070] ρ — density of coal flow on the feed conveyor belt;

[0071] b) Method for adjusting the reduction ratio:

[0072] The reduction ratio can be increased and the sample retention amount can be increased by adjusting the opening size D of the divider.

[0073] The opening sizes of the first reducer 5 and the second reducer 6 can be adjusted simultaneously or individually. Assuming the opening sizes of the two reducers are D1 and D2 respectively after adjustment, the reduction ratio is adjusted as follows:

[0074]

[0075] Where: D1—the opening size of the first divider; D2—the opening size of the second divider; W belt —Reduced feed belt width.

[0076] Example 1

[0077] A power plant uses a mechanical sampling device with a reducer arrangement based on the method of this invention. The operating parameters are as follows:

[0078] Width of feeder belt 2 (reduced size): W belt =0.30m;

[0079] The output particle size of the crusher, i.e. the nominal maximum particle size of the coal sample being reduced, is d = 6 mm.

[0080] The operating speed of the feed belt 2 is: ν belt =0.30m / s;

[0081] 1. The time interval Δt(s) of the divider operation:

[0082]

[0083] The operating time interval of the splitting motor is then adjusted to 2 seconds via the PLC controller.

[0084] 2. The opening size of the first reducer 5 and the second reducer 6 is not less than three times the nominal maximum particle size of the coal sample to be reduced. Then, the opening size of the two reducers is adjusted to D = 18mm, that is, 0.018m.

[0085] a) Calculation of reduction ratio:

[0086] Sample retention volume per cycle of the fraction reduction device:

[0087] The amount of coal sample reduced per operation of the reduction unit; m 煤样 =2·W belt ·W belt ·H 煤流 ·ρ

[0088] Reduction ratio:

[0089] The reduction ratio r is approximately 1:12.

[0090] b) Method for adjusting the reduction ratio:

[0091] The reduction ratio can be increased and the sample retention amount can be increased by adjusting the opening size D of the divider.

[0092] Assuming the reduction ratio needs to be adjusted to approximately 1:8, then r′=1 / 8. After adjustment, the opening sizes of the two reducers will be D1 and D2, respectively, which should satisfy:

[0093]

[0094] That is, adjust (D1+D2) by approximately 53mm, and ensure that both D1 and D2 are not less than 18mm. The following adjustment methods can be selected:

[0095] A. Adjust both D1 and D2 to 27mm; or B. Adjust D1 to 30mm and D2 to 25mm.

[0096] Example 2

[0097] The sampling system of the mechanical coal sampling device used in a power plant (B) was optimized using the method of this invention. The sampling precision and ash content bias of the sampling system before and after optimization are as follows:

[0098] Precision tests and ash content bias tests were conducted before and after optimization according to the standard method of GB / T19494.3.

[0099] 1) Precision test results:

[0100] Table 1 Comparison of precision test results before and after optimization of the sampling system of the mechanical coal sampling device at Power Plant B.

[0101]

[0102] As shown in Table 1, after optimization, the sample preparation precision of the sample preparation system decreased from 4.90% to 2.66%, and the sample reduction precision of the sample preparation system was significantly better than that before optimization.

[0103] 2) Ash content bias test results:

[0104] Table 2 Comparison of Ash Content Bias Test Results Before and After Optimization of the Sampling System of the Mechanical Coal Sampling Device at Power Plant B

[0105]

[0106] As shown in Table 2, before the sample preparation system was optimized, the average ash content bias of the retained samples was -2.153%, with a confidence limit range of -0.978 to -3.328%. After the performance optimization of the sample preparation system according to the present invention, the average ash content bias of the retained samples was -0.625%, with a confidence limit range of -0.119 to -1.131%. The average ash content bias decreased from -2.153% to -0.625%, and the confidence range also decreased from ±1.175% to ±0.506%, significantly improving the precision and accuracy of the sample reduction.

Claims

1. A coal mechanical sampling device sampling system performance optimization device, characterized in that, The coal flow shaper (1) and two cross-belt splitters are installed on the splitting feed belt (2) of the mechanical sampling device, the running tracks of the two cross-belt splitters are arranged at an angle of 45° with the center line of the splitting feed belt (2), and the running tracks of the two cross-belt splitters are arranged at an angle of 90°. The coal flow shaper (1), the splitting feed belt (2), the first splitter (5), the second splitter (6), the first splitting motor (3), the second splitting motor (4), the PLC controller, the first sample port (7), the second sample port (8) and the discard port (9) are further included. The first splitter (5) and the second splitter (6) are arranged on the splitting feed belt (2), the running tracks of the first splitter (5) and the second splitter (6) are arranged at an angle of 45° with the center line of the splitting feed belt (2), the running tracks of the first splitter (5) and the second splitter (6) are arranged at an angle of 90°, the first splitter (5) is connected with the first splitting motor (3), the second splitter (6) is connected with the second splitting motor (4), the first sample port (7) is arranged at the bottom end of the first splitter (5), the second sample port (8) is arranged at the bottom end of the second splitter (6), and the discard port (9) is arranged at one end of the splitting feed belt (2); the coal flow shaper (1), the splitting feed belt (2), the first splitter (5), the second splitter (6), the first splitting motor (3), the second splitting motor (4) are connected with the PLC controller. The opening size of the first splitter (5) and the second splitter (6) is not less than three times of the nominal maximum particle size of the coal sample.

2. An optimization method based on the optimization system of the coal mechanical sampling device sampling system performance optimization system of claim 1, characterized in that, The method comprises the following steps: 1) The coal sample falls from the outlet of the crusher to the splitting feed belt (2), the splitting feed belt (2) conveys the coal sample, and the coal sample is shaped by the coal flow shaper (1); 2) The first splitting motor (3) and the second splitting motor (4) are started after the splitting feed belt (2) runs, the splitting feed belt (2) conveys the coal sample to the second splitter (6), the first splitting motor (3) and the second splitting motor (4) are simultaneously started to drive the second splitter (6) and the first splitter (5) to run and cut the coal flow; 3) The cut sample of the coal flow cut by the first splitter (5) falls to the coal sample collecting barrel through the first sample port (7), and the cut sample of the coal flow cut by the second splitter (6) falls to the coal sample collecting barrel through the second sample port (8); 4) The coal flow not cut by the first splitter (5) and the second splitter (6) enters the discard sample returning device through the discard port (9).

3. The optimization method of claim 2, wherein, The thickness of the shaped coal sample is not more than three times of the nominal maximum particle size of the coal sample, and the width is less than the width of the splitting feed belt (2).

4. The optimization method of claim 2, wherein, The opening size of the first splitter (5) and the second splitter (6) is not less than three times of the nominal maximum particle size of the coal sample.

5. The optimization method of claim 2, wherein, The running time interval Δt of the first splitter (5) and the second splitter (6) is calculated by the following formula: wherein: W belt — the width of the slitting feed belt; ν belt - the running speed of the dividing feeder belt.

6. The optimization method of claim 2, wherein, The splitting ratio of the first splitter (5) and the second splitter (6) is calculated by the following formula: wherein: W belt - the width of the pinch belt D is the opening size of the splitter; H 煤流 — the thickness of the coal stream on the thinning feed belt; ρ is the density of the coal flow on the splitting feed belt; m 留样 - the sample quantity left over from one run of the dividing apparatus; m 煤样 - the quantity of coal sample that is divided per run of the division device.

7. The optimization method of claim 6, wherein, sample quantity per run of the splitting device The amount of coal sample m to be divided per one operation of the dividing device 煤样 = 2 · W belt · W belt · H 煤流 · p.

8. The optimization method of claim 6, wherein, The splitting ratio is increased by adjusting the opening size of the first splitter (5) and the second splitter (6), and the increased splitting ratio is calculated by the following formula: D1 - first splitter opening size; D2 - second splitter opening size; W belt — Pinch feed belt width.

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