Microcomputer control system of the hottest white

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White cement raw meal microcomputer control system

1 System functions and characteristics

raw meal microcomputer control system is a subsystem of "white cement microcomputer production control and management system" developed by Hangzhou Institute of electronic technology for Changxing white cement plant (compared with the upper computer, it is also called the lower computer or raw meal system for short). It has the functions of raw material proportioning control, grinding control of two raw material vertical mills and homogenization control. It can make the four raw materials of limestone, white mud, porcelain stone and fluorite required for white cement reasonably prepared. After grinding, mixing and homogenization, it can provide kiln raw materials with qualified tcaco3 titration value and fineness for calcination, so as to ensure clinker quality, improve output and reduce energy consumption. The specific functions of the system are as follows:

automatic calculation or manual setting of raw meal proportioning can make raw meal proportioning accurately and organically

control the two raw meal mills to work near the best working point, and coordinate with the batching

homogenization control to improve the qualified rate of raw materials entering the kiln

it has metering function for raw materials and raw materials in grinding head bin

it has automatic/manual control mode to ensure continuous production

it has the ability to control the automatic startup according to the sequence required by the process

it has various fault diagnosis and alarm functions

it can display the working conditions in Chinese characters in real time and monitor the production

be able to communicate with the upper computer, provide working condition table, shift report, tcaco3 error of raw meal and other data, and accept the intervention of the upper computer

it can input/modify the chemical composition of raw materials and production parameters through the keyboard, input raw material test data, and conduct man-machine dialogue

has printing function

the system has the following characteristics:

because the bucket scale of the system adopts dynamic detection and static measurement methods, the measurement accuracy is better than the belt electronic scale, so that the raw material quality is stable and meets the production requirements

this system can organically integrate the raw material batching, grinding, homogenization and other processes

the industrial control machine used makes the microcomputer isolated from i/o, and the operation is safe and reliable

because there are many user commands, the system can use these commands for various interventions without stopping

this system is easy to operate and can be mastered with a little training

2. System composition

the configuration of the raw material system is composed of an industrial control machine, a green display, an 80 column printer, a 101 key standard keyboard, seven electronic scales and two electric vibrator control boxes. In addition, the control objects of the system are the batching line (including five raw material warehouses, hopper bodies, charging and discharging electric vibrators, conveyor belts and hoists) and two vertical mills (including external grinding head silos, feeding electric vibrators, grinding bodies, host machines and fans, as well as analyzer motors, etc.); There are also power distribution cabinets, AC voltage regulators and control consoles for power supply

Figure 1 Diagram of industrial control computer and i/o connection

industrial control computer is wac-iii computer produced by Wuhan Institute of computer application development, and its connection with i/o is shown in Figure 1. The industrial control machine outputs 19 switching values through the switch plug board, which are used to control the start and stop of the power supply of the screw air pump, the 15 meter auger, the analyzer, fan and host of mill 1, the analyzer, fan and host of mill 2, the hoist, conveyor belt, flap, fault alarm and electric vibrator control box, as well as the on and off of the standby limestone discharging electric vibrator and five charging electric vibrators. Six analog quantities are output through the d/a plug-in board to control the feeding speed of four hoppers of the lower splint 8 and the feeding volume of two vertical mills on the upper part of the fixture base 9. Through the a/d board, a total of 17 input channels are used to collect the weighing data of seven electronic scales, four current data and two speed data of two vertical mills, as well as the data of feeding control quantity and given quantity of vertical mills. Each party should participate in the ranks of "green packaging" to provide the basis for material allocation and vertical mill control

3. Batching control

there are five hoppers in the batching line, which are respectively called limestone 1, limestone 2, white mud, porcelain stone and fluorite bucket (or bucket 1 ~ bucket 5), which are used for batching four kinds of raw materials of white cement, and limestone bucket 1 is used for standby. Each hopper has a raw material bin, a charging electric vibrator (or an electric vibrator), a bucket body, and a discharging electric vibrator (or an electric vibrator). The power on vibrator is controlled by the switching value to load the raw materials in the silo into the bucket body, which is supported by three pressure sensors to collect the feeding amount of each bucket; Lower the electric vibrator to lower the material in the bucket onto the conveyor belt at a certain rate. The four kinds of raw materials cover each other in the shape of "sandwich bread"

in order to ensure the batching accuracy, the system adopts intermittent batching, dynamic detection and static measurement, so that the cumulative relative error tends to zero. In principle, the process of each loading and discharging cycle of each hopper is shown in Figure 2. In fact, in the whole loading and discharging cycle (t=t loading +t discharging), the system loads the hoppers one by one under the program control, and then discharges the hoppers one by one. Especially during discharging, in order to ensure the uniform coverage of all materials, the opening of the discharging electric vibrator is not synchronous, and its time difference is the time interval from one hopper to another at a certain point of the conveyor belt. For example, bucket 2, bucket 3, bucket 4 and bucket 5 are used for batching, and the schematic diagram is shown in Figure 3. The hopper clearance is L2, L3 and L4 respectively. If the conveyor belt speed is V, the time interval between buckets is t2=l2/v, t3=l3/v, t4=l4/v respectively. Obviously, during discharging, the discharging of bucket 2 should be delayed after T2, and bucket 3 will start discharging; Test method for asphalt waterproof coiled material after time delay T3 GB 328.1 ~ 328.7 (8) 9, bucket 4 discharging; After delaying T4, bucket 5 is discharged; After delaying T5 again, the system will enter the loading cycle. Then, the loading and discharging process is repeated

Fig. 2 loading and discharging process of each bucket

Fig. 3

the control calculation formula for each hopper is:

the discharging amount in this cycle = calculation, and the market share of discolored materials in the construction industry will depend on the manufacturer's R & D flow × T-excessive discharge in the previous cycle

excessive discharge in this cycle = actual discharge in this cycle - required discharge in this cycle

cumulative relative error = cumulative error/cumulative required discharge

= excessive discharge in the nth cycle/(n × Calculated flow × T)


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