ACS TP of the ball mills "ШБМ 287/410" of the boiler "БКЗ 160–100 ПТ"

01.07.2010 09:41 Age: 15 yrs Category: By: Roman Savochenko

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Company: «Kramatorskteploenergo» Ltd.

Work: Automation of the loading of two ball mills "ШБМ 287\410"

Start date: 07.2009

Performers:

• Belousov E.M. - engineering manager
• Sadovoi A.V. - scientific adviser
• Savochenko R.A. - development of the PLC firmware, programming of the PLC and top-level
• Lysenko M.S. - top-level programming
• Zaichuk E.N. - development of algorithms
• Birukov V.V., Lesov L.I. - control cabinet's design

1. Automation object

On balance of the "Kramatorskteploenergo" Ltd. there is the heat electropower station composed of four working boilers "БКЗ 160–100 ПТ" (6, 7, 8 and 9). Boilers produce steam with pressure of 100 kg/cm2, with a nominal capacity of 160 t/h on the single boiler. The fuel of the boilers is natural gas and coal dust. Currently much attention is paid to the using of coal in steam producing because of high gas prices. The 7, 8 and 9 boilers have a working system of dust-training, which provides boiler with dust.

The process of dust-training includes: workshop of coal-preparation, the carrier of coal to the bunkers of the ball mills, two ball mills and dust bunkers.The subject of this project is the automatic control of loading process of the ball mills.

The company uses ball mills "ШБМ 287\410". Functional scheme of a ball mill with automation components is shown in Figure 1.

2. ACS TP (Automatic Control System of Technological Process)

Structure scheme of the ACS TP is shown on the Figure 2, composite nodes of which are two controllers cabinets "PLC 1", "PLC 2" and two operator workstations "АРМ 1", "АРМ 2".

 

Based on the structure, ACS TP consists of the automation object - mill, controllers ("PLC 1" and "PLC 2"), as well as of two workstations ("АРМ 1" and "АРМ 2").

Each controller operates independently with the mills of separate boiler. For example, the "PLC 1" controller controls the mills of the boiler 7, and "PLC 2" - with the mills of the boiler 9.

The technological process data are concentrated and presented on the workstations. Each workstation presents the TP data of all boilers. With each other workstations are connected in redundant scheme that prevents data loss at the time of stopping one of the workstations. In order to optimize the load on the controller the inquiry of controllers makes only one workstation, while another workstation is receiving data from the main one. The main workstation is "АРМ 1", which performs a direct inquiry of controllers. In case of failure of the "АРМ 1" the controller's inquiry performs "АРМ 2", and makes it until the restoration of an "АРМ 1". In the process of restoration after failure of the workstation the synchronization of archives depths up to 1 hour is made. Restoration of the archives for the longer time interval is made simultaneously with access to these archives.

2.1. PLC

As a programmable logic controller it is used in the PLC LP-8781 of ICP DAS company of LinPAC family. The industrial controller of this family is the first product built on the x86-compatible processor, the previous controllers of this family were based on ARM processor. Besides the x86 processors these controllers have significant resources of memory and disk space.

A special feature of the technological process of this project is the availability of specific requirements to the resources and functions of the controller having the small set of parameters. Moreover, the decisive factor is the limited funding. All these requirements are satisfied by a LP-8x81 family of controllers:

• relatively low price;
• high performance for PLC;
• architectural and programmatic openness of the PLC;
• industrial design and extended temperature range.

PLC (Fig. 3) is structurally made in a modular manner, where the modules are installed in the rack. Rack is combined with a processor module and can have 1, 3 or 7 slots for expansion modules. Expansion modules can be of two types, namely modules in parallel and serial bus. Modules on the parallel bus (I-8x) are fast. Modules on the serial bus (I-87x) are installed on the bus of RS-485 interface and operate at a speed of 115000 bps on the DCON protocol. In addition to modules directly into the rack the controller can be expanded with additional racks with modules on the serial bus (I-87x) through the serial interfaces of the processor.

ACS TP capacity for one boiler is: 18AI, 2AO, 10DI, 16DO. Hence the controller is required with the number of at least 6 expansion slots. Proceeding from this the LP-8781 controller is selected and the following modules for connection of external signals:

Slot	Module	Note
1, 2, 3	LP-8781	Rack for the 10 slots with a processor in the slots 1-3
4	I-87019RW	8 AI channels of the general purpose (inputs of the A mill).
5	I-87019RW	8 AI channels of the general purpose (inputs of the B mill).
6	I-8017HW	Module of the fast ADC (10 kHz) for two channels of vibration signals.
7	I-87024W	4 AO channels to control two variable frequency drives of feeders of mills A and B.
8	I-8042W	16 channel of DI and DO of general purpose; only input channels are used.
9	I-87057W	16 channels of general purpose DO.
10	Free

 

For the UPS connection the serial interface COM2 of controller is used.

There are some important features of controllers' adjustment:

• It was built the latest version of driver UPS nut-2.4.1.
• To ensure the stable and uniform work of the serial interfaces in the mode of real time priorities using it was necessary to set priority 20 of the real time for the kernel thread "events / 0". Setting the priority is made in the first run of the procedure of inquiry the UPS of the runtime of controller on OpenSCADA by the following code: 

• The 5 priority of the real time is set for incoming transports, in order to improve the uniformity and reactivity in response to requests from the top level.

Controllers are mounted in the cabinet with the size 2000x800x400, which includes machines, terminal blocks, relays, and UPS separate for each boiler.

2.2. Workstation

Workstations of the operator are based on the office PC with the following configuration:

Component	Name
Processor	AMD Athlon 64 X2 5200+
System board	ASUS M3N78
Random access memory	2 x DDR2-800 1024Mb Hynix PC6400 orig.
HDD	WesternDigital WD1600AAJS 160Gb SATA300
Optical drive	DVD-RW GH20NS10 20х SATA
Computer case	ASUS TA-863 400W FSP
Keyboard	Logitech Deluxe 250 Keyboard Black PS/2
Mouse	Logitech RX300
Display	19" Samsung SM 923NW 300cd 1000:1 170/160 5ms RGB (LS19HANKSHED)

 

Both the system units are placed in the cabinet of the operator's table. The operator's table is equipped with two separate display of workstations and mouses. Cabinet with system units was closed with doors on both sides. On the doors the filters are installed, and one of them has fan. Despite of the presence of the fan and because of the large saturation of the room with coal dust the overheating of the system units and failures took place. To solve this problem, it was optimized the air moving in the cabinet, and also lowered the frequency of workstation's processors from 2500 to 1600 MHz.

At workstations was installed the system software ALTLinux 5.1 and SCADA-system OpenSCADA 0.6.4.2.

The following activities on the system-wide configuration were done:

• The time synchronization was configured of "PLC 1", "PLC 2" and "AРM 2" with "АРМ 1".
• An account of the operator "operator" with password "123456" was created.
• An automatic loading of the working interface on behalf of the operator and the launch of the OpenSCADA with the ball mills ACS TP project was configured.
• KDE desktop environment is configured to eliminate unnecessary functions when working with dialog boxes and excluding the possibility of closure of the operator interface be the mouse.

3. Algorithms

The control algorithms of the ball mills are quite complex, due to the following factors:

• The use of indirect mechanisms to obtain the values of the level of coal in the mill.
• Accounting of different ways of control the loading of the mill, from the direct regulation of temperature of dusty mixture at the outlet from the mill to control the loading on the calculation of the coal level inside the mill.

Using the algorithms the programs of the controller designed for loading control of ball mills were created. In the algorithms and programs the analog and digital signals coming from the inputs (to output) of analog and discrete modules of the controller, the signals, generated by the workstation, and the intermediate signals, generated on their basis, were used.

Programs are implemented in user programming languages, of the OpenSCADA system. Block schemes are implemented in the environment of the DAQ.BlockCalc module, but the realization of the blocks itself and templates of parameters - on the JavaLikeCalc language of the DAQ.JavaLikeCalc module of the OpenSCADA system.

3.1. Pre-processing

For pre-processing of analog signals after ADC of the analog input module of the controller the template of parameters was created with the following functions:

• detecting of uncertainty (the break, out of range of acceptable values);
• corrections using the calibration coefficients;
• filtrations;
• bring to the engineering (technological) units;
• formation of the alarm bits for violations of borders;
• simulation of analog input as with the built-in function, and with the external input, which can be used to connect the signal model.

Based on this template the additional templates were created:

• template of the parameter of manual input, with the additional function of input the value;
• template of the universal PID parameter with the reflection of its own attributes of the analog and pulsed regulator.

For the grouping and processing the discrete signals the template of a discrete parameter was created, which allows you to:

• combine two digital inputs and three digital outputs in the configuration of pumps and valves.

3.2. General algorithms

Common algorithms are summarized in two block schemes for each mill. The first block scheme contains the contours of analog regulators and work with a period of 500ms. The second block scheme contains the contours of pulsed regulators and operates with a period of 100 msс.

4. Economic effect

As a result of the work received a significant economic effect, the calculation and the nature of which is held in the table below. The effect is calculated by the customer based on actual statistical data. In the period from 21/06/2010 to 30/06/2010 was work in manual mode and without ACS. In the period from 21/08/2010 to 30/08/2010 ACS SHBM worked in automatic mode.

№	Name of a parameter	Unit	21/06/2010 - 30/06/2010	21/08/2010 - 30/08/2010
1.	Consumption of coal	tons	3235	2880
2.	Electricity consumption for grinding	kWh	132780	98066
3.	Specific power consumption for grinding	kWh/ton	41.04	34.05
4.	Milling dispersity	%	8.70	7.60
5.	Combustible in the ash	%	31.90	30.60
6.	Boiler efficiency, gross	%	83.40	83.76
7.	Reducing power consumption for grinding	kWh	-	20131
8.	Fuel Savings	tons	-	10.40

 

The act of pilot tests of development SAU SHBM customer, describing the economic effect can be downloaded from the link.

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