CN111221368A - Double closed-loop control method for product yield and quality used in coal washery - Google Patents
Double closed-loop control method for product yield and quality used in coal washery Download PDFInfo
- Publication number
- CN111221368A CN111221368A CN202010184107.1A CN202010184107A CN111221368A CN 111221368 A CN111221368 A CN 111221368A CN 202010184107 A CN202010184107 A CN 202010184107A CN 111221368 A CN111221368 A CN 111221368A
- Authority
- CN
- China
- Prior art keywords
- coal
- controller
- closed
- loop control
- control system
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003245 coal Substances 0.000 title claims abstract description 118
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000005406 washing Methods 0.000 claims abstract description 48
- 238000002156 mixing Methods 0.000 claims abstract description 26
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 230000008569 process Effects 0.000 claims description 5
- 238000003908 quality control method Methods 0.000 claims 1
- 239000000047 product Substances 0.000 description 23
- 238000002360 preparation method Methods 0.000 description 11
- 230000008859 change Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000012216 screening Methods 0.000 description 3
- 239000010878 waste rock Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- -1 gangue Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D27/00—Simultaneous control of variables covered by two or more of main groups G05D1/00 - G05D25/00
- G05D27/02—Simultaneous control of variables covered by two or more of main groups G05D1/00 - G05D25/00 characterised by the use of electric means
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B11/00—Automatic controllers
- G05B11/01—Automatic controllers electric
- G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
- G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/05—Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/10—Plc systems
- G05B2219/15—Plc structure of the system
- G05B2219/15039—Display of reference, set value, of measured, feedback value
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
A double closed-loop control method for product yield and quality used in a coal washery is characterized by comprising the following steps: a production closed-loop control system and a quality closed-loop control system, the production closed-loop control system comprising: a coal feeder motor driven by a belt scale, a controller and a frequency converter; the quality closed-loop control system comprises: a coal blending flashboard controlled by an online ash detector, a controller and an electric actuator; the belt scale measures the washing flow to obtain a washing flow value signal; the online ash detector measures the ash content in the product to obtain an ash content value signal; the frequency converter controls a coal feeder motor; and the electric actuator controls the opening of the coal blending inserting plate.
Description
Technical Field
The invention relates to a double closed-loop control method for product yield and quality used in a coal washing plant.
Background
The raw coal for coal mining contains a large amount of impurities such as gangue, coal slime and the like, and the impurities not only bring heavy burden to coal transportation, but also restrict the application range of the coal and seriously influence the economic benefit of the coal industry. This requires the coal preparation plant to process the raw coal mined from the mine into the product coal required by the market. At present, coal preparation processes and coal preparation machines are mature, enterprises generally set one or more coal preparation modes according to selected coal types, and once the coal preparation processes are determined, the coal preparation processes are difficult to change.
Taking the dense medium cyclone process as an example, the method can be roughly divided into the following steps:
1. raw coal preparation system: the raw coal is fed by a coal feeder below a raw coal bin, a raw coal washing preparation belt distributes the raw coal to two fly-over sieves through a coal blending scraper machine, and after the raw coal is classified by the two fly-over sieves, oversize materials enter a washing preparation scraper machine. The method comprises the following steps that (1) screened slack coal enters a screened slack coal blending scraper conveyor, an electric coal blending inserting plate is installed on a bottom plate of the screened slack coal blending scraper conveyor, the opening degree of the coal blending inserting plate is adjusted to control the screened slack coal to enter a coal washing system through a washing preparation scraper conveyor, and if the coal blending inserting plate is fully opened, full washing of raw coal is achieved, and the maximum washing amount is achieved; if the coal blending flashboard is completely closed, the screened powder coal completely moves through the screened powder belt conveyor to realize the minimum washing amount. And (3) mixing the screened slack coal with the washed clean coal through a screening belt conveyor to form a final product, adjusting the washing proportion by adjusting the coal blending inserting plate, and enabling the produced product coal to reach the qualified index of the product by adjusting the washing proportion.
2. A coal washing system: conveying coal to a cyclone preselection barrel by a washing preparation scraper, pressurizing and injecting suspension liquid in a medium combining barrel into the cyclone by a qualified medium pump, generating rotary liquid flow in the preselection barrel, carrying materials into the cyclone barrel body for sorting, separating raw coal according to density under the action of spiral flow, throwing a heavy product (gangue) to the outermost side of the wall of the cyclone barrel under the action of centrifugal force, and discharging the heavy product (gangue) from an outlet in a tangential direction; light products (clean coal) are concentrated at the central part of the cyclone cylinder due to the relatively low density and are discharged from a neutral hole at the lower part. Removing medium of the heavy product through a gangue medium removing sieve; the light product is subjected to medium removal by a clean coal medium removal sieve and is dehydrated by a centrifuge. Thus, the coal washing process is completed.
3. The product warehousing system comprises: the products discharged by the coal washing system are divided into gangue and washed clean coal, and the washed clean coal is mixed with the screened slack coal to be called washed mixed coal, namely: and (5) producing coal. The waste rock enters a waste rock bin through a waste rock belt conveyor, and the washed and mixed coal finally enters a product bin through a coal mixing belt conveyor.
The quality of the product coal is influenced by a plurality of factors and is totally summarized into three points:
firstly, the method comprises the following steps: the fluctuation of the coal quality of raw coal is large, which is the most critical point and can not be changed technically;
secondly, the method comprises the following steps: instability of washing amount; when the washing quantity is low, the system is not full, the power consumption per ton of coal is high, and the driving time is prolonged; when the washing quantity is large, the system overload operation can cause major production accidents such as vehicle pressing and the like.
Thirdly, the method comprises the following steps: the washing proportion is not adjusted reasonably (the washing proportion is the ratio of the coal entering the coal washer to the selected raw coal).
Due to the unstable feeding amount, the coal quantity flowing through the openings with the same size of the coal blending inserting plate is different. The method is characterized in that a centralized control room worker reads data on an online ash meter arranged on a product belt conveyor, data of a belt scale on a powder screening belt and washing amount, and adjusts the data through experience, so that different people have great difference in operation results, and no unified standard exists.
When the washing proportion is not appropriate and needs to be adjusted, a call is made to inform field workers of increasing or decreasing the flow rate of the belt scale of the screening end belt conveyor, and the field workers adjust the size of the plug board through experience to achieve the purpose of adjusting the washing proportion. There are several problems with such an adjustment: 1. firstly, whether the personnel in the centralized control room can timely find that the coal quantity changes to the degree required to be adjusted, generally, when the washing quantity is higher than or lower than the expected washing quantity by more than 50 tons/hour, the personnel in the centralized control room can contact the field personnel, and if the personnel in the centralized control room cannot timely find that the coal quantity changes, or the coal quantity is always less than 50 tons/hour away from the target coal quantity, the personnel in the centralized control room cannot timely adjust the coal quantity; 2. the feeding of the coal feeder is controlled by the insertion plate, and controlled by different workers, or the feeding is adjusted differently by the same person under different coal quality conditions, so that larger coal quantity change is caused; 3. thus, the time for adjusting the coal amount by manual board insertion is too long. Again, this has no uniform standard and no accuracy.
Disclosure of Invention
Aiming at the technical problem, the invention provides a double closed-loop control method for product yield and quality used in a coal washing plant.
A double closed-loop control method for product yield and quality used by a coal washing plant comprises the following steps: a production closed-loop control system and a quality closed-loop control system,
the closed-loop production control system comprises: a belt scale, a controller, a frequency converter and a coal feeder motor;
the quality closed-loop control system comprises: the system comprises an online ash detector, a controller, an electric actuator and a coal blending plugboard;
the belt scale measures the washing flow to obtain a washing flow value signal; the online ash detector measures the ash content in the finished product to obtain an ash content value signal; the frequency converter controls a coal feeder motor; the electric actuator controls the opening of the coal blending inserting plate; the working process of the yield closed-loop control system is as follows:
(1) sending the washing flow signal measured by the belt scale to the controller;
(2) the controller compares, analyzes and calculates the washing flow value signal and a preset target value, and then sends a control signal to the frequency converter;
(3) the frequency converter controls the rotating speed of a motor of the coal feeder according to the control signal;
(4) and repeating the steps.
The working process of the quality closed-loop control system is as follows:
(1) sending the ash content value signal measured by the online ash detector to the controller;
(2) the controller compares, analyzes and calculates the ash content value signal and a preset target value, and then sends a control signal to the electric actuator;
(3) and the electric actuator directly drives the opening of the coal blending inserting plate according to the control signal.
(4) And repeating the steps.
The controller adopts a PID controller or a PLC controller with a PID function.
The frequency converter is directly connected with a motor of the coal feeder.
The electric actuator directly controls the opening of the coal blending flashboard.
The ash content value signal range is 4-20 ma or 0-5 v, and the output signal range of the controller is 4-20 ma or 0-5 v.
The washing flow value signal range is 4-20 ma or 0-5 v, and the output signal range of the controller is 4-20 ma or 0-5 v.
Drawings
FIG. 1 is a graph showing the variation of the manually controlled washing input (time on the abscissa and yield on the ordinate).
FIG. 2 is a graph showing the relationship between the reaction time and the flow rate in the case of manually adjusting the flow rate (time on the abscissa and yield on the ordinate).
Fig. 3 is a PID control schematic.
Fig. 4 is a schematic diagram of the system.
In the figure: the system comprises a coal feeder 1, a belt scale 2, a grading sieve 3, a scraper 4, a coal washing system 5, a gangue bin 6, a finished product belt 7, a finished product bin 8, an online ash content meter 9, a screen dust belt conveyor 10, an electric actuator 11, a screen dust coal blending scraper 12 and a controller 13, wherein hollow arrows represent signal flow, and solid arrows represent coal flow.
Detailed Description
In order to more clearly illustrate the present invention, embodiments of the present invention are further described below with reference to the accompanying drawings.
Fig. 1 is a flow rate change chart caused by manual adjustment of the washing amount before the method is not used, specifically: coal washing plant of Zhu Jidong Ore, Huainan city, Anhui province, 10 months in 2019, 21 days in night, 20 days: when raw coal is washed in the condition of 10 months, 22 days, 8:50 in 2019, the flow rate of the belt conveyor at the point A is 1238t/h at the point 0:22 minute, 955t/h at the point B, 283t of reduction of the flow rate of the belt conveyor in less than one hour, and when the maximum amount D of the shift exceeds 1381t/h, the processing capacity of equipment is exceeded; the lowest flow rate C point is 500 t/h, and is less than half of the normal handling capacity.
FIG. 2 is a graph showing the relationship between the reaction time and the production of a coal blending plug board adjusted before the method of the present invention is used, specifically: coal washing plant of Zhu Jidong Ore, Huainan city, Anhui province, 10 months in 2019, 22 days in night, 20 days: the raw coal washing condition is as an example from 40 to 2019, 10, 23, 9: 00: the treatment capacity should be about 1138t/h, the belt conveyor flow rate at point A is 1041t/h at 23:35 minutes, the belt conveyor flow rate is about 1138t/h at point B, more coal is used for adjusting the coal amount by one hour, and the time at point C is 5: 08, the coal amount is 928t/h, the field addition is informed to reach 5:55 until the coal amount basically reaches the requirement of the production process, and the time is 47 minutes.
The system diagram of the invention is shown in fig. 4, and comprises: the coal blending plug board is controlled by a belt scale, an online ash detector, a controller, a frequency converter dragging a coal feeder motor and an electric actuator. The method comprises the steps that a belt scale monitors the flow of raw coal entering washing to obtain a washing flow value signal, an online ash detector is installed on a product coal belt conveyor to monitor the quality of product coal, the washing flow value signal and the ash content value signal have values in the range of 4-20 ma or 0-5 v and are respectively sent to a controller, the controller adopts a PID (proportion integration differentiation) controller or a PLC (programmable logic controller) with a PID function, the controller in a yield closed-loop system is connected with a frequency converter, and the frequency converter drags a coal feeder motor; the controller of the quality closed-loop control system is connected with the electric actuator and is used for adjusting the opening of the coal blending inserting plate; the controller respectively analyzes and calculates the washing flow value signal and the ash content value signal, and in a yield closed-loop system, the controller continuously sends a control signal with a signal range of 4-20 ma or 0-5 v to the frequency converter; the frequency converter controls the rotating speed of the motor according to the continuous control signal to achieve the purpose of regulating the flow, namely realizing the stable regulation of the real-time flow; in the quality closed-loop control system, a controller continuously sends a control signal with a signal range of 4-20 ma or 0-5 v to an electric actuator, and the electric actuator controls the position of a coal blending inserting plate according to the continuous control signal to adjust the washing proportion, so that the aim of continuously adjusting the product quality is fulfilled. The principle of the PID controller is shown in fig. 3. The method specifically comprises the following steps: the PID controller compares system actual data c (t) collected from a measurement original with an artificially set target value r (t) to obtain an error value e (t), i.e. e (t) = r (t) -c (t), and linearly combines proportion (P), integral (I) and differential (D) of the error to form a control quantity to control a controlled object.
Claims (6)
1. A double closed-loop control method for product yield and quality used in a coal washery is characterized by comprising the following steps: a production closed-loop control system and a quality closed-loop control system,
the closed-loop production control system comprises: a coal feeder motor driven by a belt scale, a controller and a frequency converter;
the quality closed-loop control system comprises: a coal blending flashboard controlled by an online ash detector, a controller and an electric actuator;
the belt scale measures the washing flow to obtain a washing flow value signal; the online ash detector measures the ash content in the product to obtain an ash content value signal; the frequency converter controls a coal feeder motor; the electric actuator controls the opening of the coal blending inserting plate;
the working process of the yield closed-loop control system is as follows:
sending the washing flow value signal measured by the belt scale to the controller;
the controller compares, analyzes and calculates the washing flow value signal and a preset target value, and then sends a control signal to the frequency converter;
the frequency converter controls the rotating speed of a motor of the coal feeder according to the control signal;
so as to achieve linear control.
2. The method of claim 1, wherein the operation of the closed-loop quality control system comprises:
sending the ash content value signal measured by an online ash detector to the controller;
the controller compares, analyzes and calculates the ash content value signal and a preset target value, and then sends a control signal to the electric actuator;
the electric actuator adjusts the opening of the coal blending inserting plate according to the control signal;
so as to achieve linear control.
3. The method of claim 1, wherein the method comprises the steps of: the controller adopts a PID controller.
4. The method of claim 1, wherein the method comprises the steps of: PLC controller with PID function.
5. The method of claim 1, wherein the method comprises the steps of: the frequency converter is directly connected with a motor of the coal feeder.
6. The method of claim 1, wherein the method comprises the steps of: the electric actuator directly controls the opening of the coal blending flashboard.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010184107.1A CN111221368A (en) | 2020-03-17 | 2020-03-17 | Double closed-loop control method for product yield and quality used in coal washery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010184107.1A CN111221368A (en) | 2020-03-17 | 2020-03-17 | Double closed-loop control method for product yield and quality used in coal washery |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111221368A true CN111221368A (en) | 2020-06-02 |
Family
ID=70831721
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010184107.1A Pending CN111221368A (en) | 2020-03-17 | 2020-03-17 | Double closed-loop control method for product yield and quality used in coal washery |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111221368A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112163764A (en) * | 2020-09-25 | 2021-01-01 | 中国神华能源股份有限公司哈尔乌素露天煤矿 | Coal feeder scheduling method, storage medium and system based on coal blending |
| CN113560033A (en) * | 2021-07-19 | 2021-10-29 | 中煤西安设计工程有限责任公司 | Intelligent coal powder-removing washing system and method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201885791U (en) * | 2010-09-25 | 2011-06-29 | 中国矿业大学 | Electronic-scale automatic-regulation device used for coal blending process in coking plant |
| CN104656594A (en) * | 2013-11-21 | 2015-05-27 | 陕西子竹电子有限公司 | Automatic coal blending system for coal mines |
| CN206710884U (en) * | 2017-05-17 | 2017-12-05 | 陕煤集团神木张家峁矿业有限公司 | Coal preparation plant customizes production Automatic Control System for Mixing Coal |
| CN110003931A (en) * | 2019-05-10 | 2019-07-12 | 北京沄汇智能科技有限公司 | A kind of coal blending control system and method |
-
2020
- 2020-03-17 CN CN202010184107.1A patent/CN111221368A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201885791U (en) * | 2010-09-25 | 2011-06-29 | 中国矿业大学 | Electronic-scale automatic-regulation device used for coal blending process in coking plant |
| CN104656594A (en) * | 2013-11-21 | 2015-05-27 | 陕西子竹电子有限公司 | Automatic coal blending system for coal mines |
| CN206710884U (en) * | 2017-05-17 | 2017-12-05 | 陕煤集团神木张家峁矿业有限公司 | Coal preparation plant customizes production Automatic Control System for Mixing Coal |
| CN110003931A (en) * | 2019-05-10 | 2019-07-12 | 北京沄汇智能科技有限公司 | A kind of coal blending control system and method |
Non-Patent Citations (2)
| Title |
|---|
| 万丽荣: "基于模糊PID 主运输自动配煤系统的研究", 煤矿机械, vol. 36, no. 01, pages 232 - 235 * |
| 凌丽伟;: "自动化配煤技术在陈四楼选煤厂的应用", 中州煤炭, no. 05, pages 79 - 82 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112163764A (en) * | 2020-09-25 | 2021-01-01 | 中国神华能源股份有限公司哈尔乌素露天煤矿 | Coal feeder scheduling method, storage medium and system based on coal blending |
| CN113560033A (en) * | 2021-07-19 | 2021-10-29 | 中煤西安设计工程有限责任公司 | Intelligent coal powder-removing washing system and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100430143C (en) | Semi-automill ball-milling type ore grinding system and its control system | |
| CA1142453A (en) | Thickener control system | |
| CN106964483B (en) | A kind of unpressurized feeding dense medium cyclone coal separation process autocontrol method and system | |
| CN110681475A (en) | Crushing production line and method for processing high-quality sandstone aggregate based on hard rock | |
| CN111221368A (en) | Double closed-loop control method for product yield and quality used in coal washery | |
| CN108483962B (en) | Intelligent control system and method for aggregate production | |
| CN103785532A (en) | Method for automatically monitoring tin ore table beneficiation | |
| CN112774849B (en) | Automatic frequency conversion regulation and control method for vertical shaft type crusher | |
| US3094289A (en) | Rock grinding system | |
| CN113426548B (en) | Control method for wet screening and dry crushing process of fine crushing workshop in machine-made gravel | |
| CA1113064A (en) | Method of controlling crushing plant | |
| CN113413999B (en) | On-line intelligent detection control method for quality of semi-finished product in grit coarse crushing production workshop | |
| US2877896A (en) | Method and apparatus for separating materials of different specific gravity | |
| CN209829578U (en) | Multistage screening system is used in fly ash production | |
| CN216406834U (en) | Slurry treatment equipment capable of automatically adapting to slurry balance shield slurry flow | |
| CN114179227B (en) | Tailing grading and reorganizing slurry reconstruction cemented filling equipment and technology thereof | |
| CN111443598A (en) | Cement vertical mill control method and device | |
| CN203155329U (en) | Intermediate crushing system for producing graphite products | |
| CN216894514U (en) | Tailing graded recombination reconstructed slurry cementing filling equipment | |
| US3697003A (en) | Grinding mill method and apparatus | |
| CN214766113U (en) | Full-line automatic control system of sand making line | |
| Song | Intelligent Control and Energy Conservation of Ball Mill | |
| CN215140881U (en) | Intelligent coal dressing production device | |
| CN214599710U (en) | Selection amount adjusting device | |
| CN116393238A (en) | Cement vertical mill parameter adjusting system and method based on PLC control |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200602 |