Humidification moisture meter control system
Background: At present, there are many compound machines or coating production lines that control the moisture content of paper through humidifiers. There is no online moisture monitoring and control on the equipment. Basically, they are taken to the laboratory for measurement after humidification, and then based on the moisture The content adjusts the amount of humidification, or operates according to the experience of the workers, so the control is seriously lagging, and the compounding machine and coating machine cannot be sampled for testing during production, and can only be sampled at the beginning and end of production. The instability caused the unqualified paper quality of thousands of kilometers.
Based on our experience in installing moisture meters in such industries, we have proposed a moisture measurement control system that controls the humidification capacity of humidifiers. Because the speed of the laminating machine or coating machine is generally more than 100 meters per minute, if the moisture of the paper is not measured in advance, and then the moisture is measured after humidification, there are already tens of meters of lag, so we proposed the humidifier Install a moisture meter in front of the machine, considering that the laminating machine or coating machine may have a speed change during the production process. The speed change will greatly affect the amount of humidification. Therefore, we have proposed a paper speed detection for the production line.
1. Install a near-infrared moisture meter 1 in front of the humidifier to measure the moisture in the paper in advance.
2. Install a near-infrared moisture meter 2 at the rear of the humidifier to measure the amount of humidification.
3. Control the spray disc speed of the humidifier through the inverter to control the humidification amount.
4. Install rotary encoders on the front and rear rollers of the humidifier and below the paper to measure the paper production speed.
5. Connect the start signal of the compound machine or coating machine to the system, and the system will be linked with the compound machine or coating machine.
Principle: When the laminating machine or coating machine is started, the system starts automatically. When the unhumidified paper passes under the near-infrared moisture meter 1, the system measures the moisture content of the paper. When the paper enters the humidifier, the system simultaneously rotates The speed measured by the encoder calculates the amount of humidification per meter (the acceleration and deceleration value of the inverter, the higher the speed, the faster the frequency conversion increases), humidifying the paper, when the paper passes through the humidifier, it is measured by the moisture meter 2 The moisture data after humidification is transmitted to the system at the same time and compared with the target moisture value set by the process. When the moisture content is higher or lower than the set value, the system modifies this corrected humidification amount per meter according to the proportion of the difference in moisture , To avoid changes in paper moisture in a period of time due to changes in the moisture content of the unhumidified paper or changes in production speed. The corrected humidification amount will be kept in the system. At the next startup, the system will control the humidifier to humidify according to the correction value to avoid the unstable moisture control of the previous section due to the humidification amount per meter at the next startup. .
1. Install paper speed detection to avoid changes in humidification caused by paper speed changes.
2. Install a near-infrared moisture meter before humidification to avoid affecting the humidification amount due to changes in paper moisture.
3. After humidification, install a near-red moisture analyzer to form a closed-loop control system to ensure constant paper moisture after humidification.
4. Linkage control of system pair and production line can realize one-key start of equipment and unmanned operation.
Remarks: Due to the different on-site process requirements, equipment conditions and operating habits of users, the automatic control of moisture content needs to be designed according to the user's process conditions, and the customization of the combined on-site conditions.