Practice of energy saving and consumption reduction for large cardboard paper machine
Since the beginning of the 21st century, China's containerboard machine has achieved rapid development, and its production capacity has broken through a record high. Therefore, energy conservation and consumption reduction are the best choice for enterprises to improve their comprehensive competitiveness. This text mainly discusses the energy saving measures in the press section, the drying section and the clean water system and the good economic benefits after implementation.
Energy saving measures
Optimization of the vacuum system of the press section
The press section of the paper machine consists of a press and a second press, one press is a blind hole press (large roll diameter), and the second press is a shoe press. There are 6 vacuum pumps in the entire press section vacuum system, which are independent of each other. Due to the normal operation of the paper machine, the vacuum of the suction box of the first and second presses is actually controlled at -35~-40kPa, while the vacuum capacity of the 7# and 8# vacuum pumps is -45kPa (actually -50kpa). Therefore, it is necessary to open the venting valve corresponding to the separation of the steam and the water in the suction box of the large cloth and the second pressure, so that a considerable waste of resources is generated. The vacuum system of the press section is now re-optimized through process innovation.
Reduce the amount of steam in the drying section
The paper machine section drying section consists of 60 drying cylinders and 8 watt cylinders. It is divided into 7 drying zones, of which 1 baking and 2 baking are designed as single row cylinders, and 3 baking is 7 double row cylinder design. It is well known that for every 1% increase in the dryness of the paper press, it is possible to save 5% of the steam consumption in the dryer section. Therefore, increasing the dryness of the press section is the key to reducing steam consumption. By improving the parameters of the two press fabrics, the warp base fabric warp is optimized from monofilament to 6 strands of silk, the air permeability of the felt is reduced from 62cfm to 57cfm. The boot cover model is also optimized with a broken groove boot. Through the above measures, the paper sheet press dryness has a more obvious improvement in the sheet press-out dryness by 0.51%.
In addition, the paper moisture also directly affects the amount of steam used. The moisture control standard of the cardboard paper is 6%~10%. Under the premise of stable paper physical indicators, it is necessary to increase the paper moisture as much as possible, which can reduce the steam consumption.
Reduce the consumption of clean water
There are some problems in the design of the original water system. First, the white water and the turbid white water have always overflowed. Second, the long-fiber turbid white water will be short of water and need to be replenished after the disintegration system is turned on. The third is AOCC turbidity. White water lacks water and needs to be replenished with water. Fourth, the white pool under the surface network lacks water and needs to be replenished with water.
Water system process optimization instructions
By detecting the white water, it was found that the white water under the multi-disc was about 400 mg/l, while the AOCC turbid white water was about 350 mg/l. Since the white water multi-disc reuse is the white paper under the paper pulp and the paper machine net, it is relatively clean, and the concentration of the two white waters is not much different. The white water can be used to replace the AOCC turbid white water. Through the pipeline connection, the white water multi-disk turbid white water pump outlet pipe is connected to the AOCC turbid white water, and the excess overflowing turbid white water is hit into the AOCC turbid white water pool, thus solving the AOCC turbid white water shortage and solving the white water multi-disc Turbid white water overflow problem.
After the OCC line short fiber is concentrated by multiple plates, the concentration can reach 10%~12%. This concentration is relatively high, and can not meet the demand of about 5% of the beating concentration. It needs to be diluted before beating. It was originally used. Since the white water multi-disc reuse is the white paper under the paper pulp and the paper machine net, the water quality of the white water is relatively clean, and the SS is within 120 mg/l. The white water white SS under the surface network is about 300mg/l. The white water under the surface layer network will always lack water and need to be replenished with water. Therefore, it is completely possible to supplement the turbid white water under the surface net with white water. Through the pipeline connection, the white water multi-plate clear water pump outlet pipe is connected to the white pool under the surface net, thus solving the problem of water shortage in the white pool under the surface net. After the disintegration system is turned on, the long-fiber turbid white water will be short of water. Through the pipeline connection, the mixed white water pump under the net is connected to the long-fiber turbid white water, and the long-fiber turbid white water also has a part to go to the white water tower, thus forming a cycle, which solves the problem of instantaneous water shortage of the long-fiber turbid white water.