Artificial leather and synthetic leather industry
Dry production process- DMF exhaust gas recovery tower DMF solution intelligent control solution
I. Existing dry liquid DMF waste gas recovery tower drainage control status:
The measurement and control of the concentration of the liquid discharged from the existing dry DMF exhaust gas recovery tower is mainly performed by manual timing monitoring. The handheld refractometer is used to measure the refractive index to convert the DMF concentration, or the Abbe refractometer is used to measure the refractive index. Methods The DMF concentration value was measured from the sampling port, and then the internal circulation concentration was adjusted based on the currently measured concentration value and the concentration value of the liquid to be controlled, and the opening or closing of the liquid discharge valve according to production experience. When the concentration is high, the discharge valve is opened or increased, and when the concentration is low, the discharge valve is decreased or closed to meet the production process requirements.
Problems and shortcomings of the existing control methods:
1. The dry DMF solution is manually monitored every 2 hours, and it is not 100% guaranteed.
2. Variations in production line production, changes in production vehicle speed, changes in coating amount formula, and changes in DMF during paper change or loading, operators cannot implement real-time control.
3. Large measurement error (up to plus or minus 1%): The refractive index measured by the Abbe refractometer is measured by a table lookup method to obtain the DMF concentration value. The corresponding relationship between the refractive index and the concentration value changes with temperature changes. The measurement error is as high as plus or minus 1%.
4. Low control accuracy (up to plus or minus 5%), low recovery efficiency and increased waste water recovery cost: controlling the valve opening degree based on the interval measurement value and operator experience may cause excessively high or low concentrations and excessively high concentrations. The system recovery efficiency is reduced, too low concentration emissions, and the recovery operation cost is high. The dry absorption tower on-line concentration meter, on-line concentration meter and DMF on-line refractometer developed and produced by our company can solve this problem well.
Third, the dry production line DMF exhaust gas recovery tower intelligent control system product introduction (DMF online concentration meter, online concentration meter)
The intelligent control system of the DMF exhaust gas recovery tower of the dry production line adopts the high-resolution DMF solution online concentration sensor for full-automatic measurement, avoiding artificial measurement errors, high measurement accuracy, and with accurate automatic temperature compensation to ensure different measurement environments , Can objectively and accurately measure the concentration of DMF solution. Equipped with controls. The user can set the concentration range of the DMF solution to be discharged through the man-machine interface of the system according to the requirements. The system will compare and calculate the concentration value currently collected by the online concentration sensor and the set concentration value. The output control signal is used to control the discharge valve to ensure the stability and accuracy of the DMF solution concentration value and improve the recovery efficiency.
4. Features of DMF concentration intelligent control system products (DMF online concentration meter)
4.1 CY-MC concentration controller (optional)
1. 5.6 inch TFT true color LCD display;
2. Powerful control function, integrated PID control, upper and lower limit control, alarm output, etc .;
3. Built-in 4 ～ 20mA analog output and relay output are used to control the actuator;
4. Built-in 4 ～ 20mA standard analog signal transmission output
5. RS485 communication output, MODBUS RTU communication protocol;
6. You can customize the control method, cleaning method, automatic cleaning time and cleaning interval time;
7, built-in EEPROM, all parameters * are stored in the host, will not be lost after power failure;
8, built-in sensor self-diagnostic function, possible failures at a glance;
9, built-in real-time curve, easy to trace historical data;
10, built-in USB2.0 port, data export is very convenient;
11.Built-in 4 DC24V @ 65mA output
12. Embedded instrument panel installation for easy system integration;
13. Ambient temperature: 0--50 ° C;
14. Power supply: 110 / 220VAC, 50 / 60HZ, power consumption: ≤20W;
15. Compact design with only 144 (W) × 144 (H) × 220 (D) peripheral dimensions and a weight of 2.5Kg
4.2 Technical parameters of DMF online concentration sensor
| Product number || CY-DMF-A || CY-DMF-D |
| Measuring range || 0.0 to 50.0% |
| Resolution || 0.1% temperature: 0.1 ° C |
| measurement accuracy || ± 0.1% temperature ± 0.5 ° C |
| measure temperature || 5 to 100 ° C (automatic temperature compensation) |
| Ambient temperature || 5 to 40 ° C |
| Input power || DC 24V |
| Key material || Sensor housing: SUS316L |
| Signal output || DC4 to 20mA || RS-232 |
| Protection class || IP67 dust and splash water |
| Most gao pressure || <1MPa |
| Product Size || ￠ 99X175 |
| Option || * Cleaning kit CY-CL77 |
* CY-DMF-D is recommended to use CY-MC concentration controller
Five, DMF concentration online measurement and control system (DMF online concentration meter, online concentration meter) implementation plan
1. DMF exhaust gas inlet
2.Internal circulation gas-water exchange
3.External circulation gas-water exchange
4.Exhaust gas outlet
5.DMF solution outlet
DMF online refractometer (online concentration sensor) system diagram is shown in the figure
The above picture is a typical dry process production line for two-stage absorption and recovery of DMF exhaust gas. The working principle of this recycling equipment is that it is easily miscible with water according to the characteristics of DMF being easily soluble in water. The recycling equipment can fully absorb and recover the exhaust gas containing DMF through the water spraying method to the dry production line oven. Purified DMF exhaust can meet the emission standard requirements. The intelligent control system of the DMF exhaust gas recovery tower of the dry production line of Changsha Chuyi Electromechanical Co., Ltd. is usually installed on the * section circulation (inner circulation) circuit. The absorption solvent (such as water) in this section comes from the second section circuit. The solvent is already in the first section. The second-stage circulation loop absorbs DMF in the exhaust gas. After further absorption in the * -stage circulation loop, the solvent absorption capacity will be reduced. The intelligent control system can monitor the concentration of DMF in the solvent in real time, determine the absorption capacity of the solvent for DMF, and decide whether to discharge it. Internally circulate the solution and whether to add fresh water to improve recovery efficiency.
As shown in the figure, the general intelligent control system is installed vertically at the inlet and outlet of the circulation pump in a bypass mode to control the drainage pump or the drainage valve.
Advantages of applying DMF concentration online measurement and control system (online concentration meter)
1. Improve measurement accuracy and reduce measurement error (up to 0.1%):
The intelligent control system of the DMF exhaust gas recovery tower is adopted, with precise automatic temperature compensation to ensure that the concentration of the DMF solution can be measured objectively and accurately under different measurement environments, with a measurement accuracy of up to 0.1%.
2. Improve control accuracy:
The system is equipped with a high-resolution detection unit and a computing system, which outputs standard control signals to control the opening and closing of the liquid discharge valve, and continuously closes the loop detection and control to ensure the stability and accuracy of the DMF solution concentration value.
3. Improve recovery efficiency:
Avoid high-concentration internal circulation waste water's ability to exchange and dilute with the exhaust gas during the recovery process, make the DMF in the exhaust gas not fully recovered and be discharged outside the tower, reduce the recovery efficiency, and cause waste of DMF.
4. Improve the degree of automation of the production line:
Can achieve 24 hours of continuous measurement and control.
5. Can set automatic cleaning time control function
The long-term operation of the wastewater will have scale and contamination on the cleanliness of the collector test surface, which will affect the actual measured objective values.We have a real-time automatic cleaning function to solve this situation.
6. Reduce waste water recycling costs and product production costs
Taking the daily discharge of 20 tons of wastewater from each dry recovery tower as an example, 600 tons of 18% DMF wastewater is required to be discharged every month as an example, totaling 108 tons of pure DMF. If an intelligent control system is used, an average increase of 2% can reduce the discharge of tap water by 60 tons (600-108 tons / 20% = 60 tons).
A. Wastewater processing cost savings of 15,600 yuan: 60 tons × 260 yuan / ton = 15,600 yuan. (The wastewater processing cost is calculated at 260 yuan per ton).
B. Water fee savings of 180 yuan: 60 tons × 3 yuan / ton = 180 yuan
Total monthly savings: 15780 yuan: 15600 + 180 = 15780 yuan / month
7. Reduce labor intensity and labor costs
There is no need to manually measure and control the DMF concentration. It is measured and controlled every 2 hours, each time is 20 minutes, which can save 4 hours per day.
Seven, DMF online concentration measurement and control system (online concentration meter, online concentration meter) customer application cases
Well-known companies such as Amway, Wenzhou Artificial Leather, Hexin, Wenzhou Aopeng Synthetic Leather, Fujian Nanfeng Artificial Leather, Black Leather