Current situation and development trend of equipment in China's paper industry (Part 2)
this technology is still blank in China at present, and its key technologies and equipment are: replacement cooking technology of cooking pot and cold spray technology and equipment.
(3) high yield pulping equipment
high yield pulping equipment is still blank in China. The technology is mature abroad, and its key equipment: co rotating twin-screw pulping machine, the structure and heat-resistant and wear-resistant materials of twin-screw pulping rotor
(4) APMP and BCTMP pulping equipment
the manufacturing of APMP and BCTMP pulping equipment is still blank in China, and small-scale equipment systems are being developed. APMP pulping equipment of 75 ~ 250t/D has been introduced in China. Foreign countries have developed this kind of equipment for more than ten years, and the technology is mature, which can provide complete sets of equipment for production lines of more than 100000 t/A. Its key technology and equipment: high compression ratio feeder, large diameter atmospheric pressure high concentration disc mill and whole process high concentration bleaching
(5) black liquor extraction equipment
high efficiency black liquor extraction equipment has developed rapidly in China, and its variety, specification and manufacturing capacity have approached the international advanced level. Its key technology and equipment is medium consistency large drum vacuum washer (with corrugated filter plate and plane valve), with a maximum area of 100m2. Double roll extruder is a key product developed by domestic enterprises. At present, the capacity of domestic equipment is 100t/d. In foreign countries, the maximum area of drum vacuum washer is more than 110m2, and the extraction rate, manufacturing accuracy and degree of self-control are high, but the price is high and the performance is significantly expensive. The extrusion concentration of double roll extruder can reach 30%, and the capacity is 300t/d. In order to pursue higher operating efficiency and low-cost operation, drum displacement washer (DD washer) has been developed and put into use abroad, which can complete four-stage washing on one washer. It has been introduced in China to make up for the gap that there is no relevant national standard and industrial standard in China
(6) screening and purification equipment
domestic pressure screens with corrugated drum and low pulse pressure screens with rod wave drum for closed screening have formed a series, close to the international advanced level. However, there is still a certain gap in accuracy and service life. The service life of similar foreign equipment is twice that of domestic equipment, and the material has good heat treatment
(7) bleaching equipment
at present, most domestic enterprises still use three-stage low concentration bleaching, which consumes large amount of water, high power consumption and serious pollution. Its development direction is ECF and/cf bleaching; The medium consistency bleaching system of waste paper pulping has been put into operation, with a capacity of 25 ~ 150t/d and a bleaching concentration of 8 ~ 12%. It is the pulping process equipment with the largest gap with foreign countries; In ECF and TCF multi effect continuous bleaching equipment, the manufacturing of medium concentration pump and medium concentration mixer is blank in China. At present, hydrogen peroxide bleaching system has been applied in mechanical pulp, chemical pulp, chemical mechanical pulp and waste pulp, with the maximum output of 50t/d. However, its preparation system still relies on imports. In foreign countries, oxygen bleaching, chlorine dioxide and hydrogen peroxide bleaching are often used in bleaching systems, and medium and high concentration is used in the whole bleaching process.
(8) alkali recovery equipment
in China, the technology of wood pulp alkali recovery and treatment equipment has been mature, and the equipment with a treatment capacity of 1200t/d has been put into operation. The capacity of straw pulp alkali recovery and treatment equipment has reached 280t/D, but the recovery rate is low and the water pollution is serious. The evaporator, the key equipment for alkali recovery, has adopted the multi effect evaporator with high-efficiency plate or plate tube combination, the pre hung white mud filter has been applied in the causticization process (the annual compound growth rate from 2014 to 2020 is expected to be 7.2% ECO), and the CD filter is being developed. At present, odor collection and combustion technology and equipment are still blank in China. Foreign alkali recovery equipment has large processing capacity, high concentration of recovered black liquor and high degree of process automation control. New jet alkali recovery furnace, plate and tube falling film evaporator, white liquor and white mud filter, odor collection and combustion technology and equipment have been adopted.
(9) white water recovery and pulp concentration equipment
white water recovery and pulp concentration equipment have developed rapidly, and efficient multi disc filters have formed a series. The recovery rate is 90% - 95%, which completely replaces the circular thickener and is close to the international advanced level
(10) waste paper pulping and waste paper deinking equipment
in China, 400t/d waste cardboard and 250t/d old newspaper and magazine paper processing systems have been put into operation, of which the key equipment drum pulper, vertical pulper, high temperature and high concentration disc thermal separator and flotation deinking tank have all been localized, close to the international advanced level, but need to develop to large specifications. There is still a certain gap between the complete set of equipment of domestic office waste paper treatment production line and imported equipment, in which high concentration hydrogen peroxide bleaching is still blank. In foreign countries, the complete set of waste paper treatment and waste paper deinking equipment has a large single production capacity, low energy consumption per ton of pulp and low operating cost per ton of pulp. The key equipment has been developed from disk type heat dispersing machine to cone type heat dispersing machine with higher efficiency and energy saving
(11) beating equipment
in China, domestic double disc refiners have formed a series with complete specifications and large market share, but the High Consistency Disc refiners used in APMP and BCTMP are still blank. In foreign countries, energy-saving and efficient medium and high consistency beating is widely used, with large single machine capacity, long service life and high degree of self-control. It has developed into a large-diameter conical refiner, which realizes the combination of dredging and grinding, and the beating quality is better.
(12) paper machine flow system
for a long time, the domestic paper machine flow system is limited by the design concept, equipment performance and manufacturing quality, and the effect of pulp uniformity and pulse reduction is poor. Domestic flow system equipment is mainly used in medium and low speed paper machines, while the flow system of higher speed paper machines is still mainly imported. At present, the M-series screen, tc-133 series slag remover and enso-vae series configured in the paper machine flow system, which partially replace the petroleum based plastic material column degasser, have been put into the market, and their applications in small and medium-sized production lines basically meet the requirements, but their market share is not high. With the further improvement of the speed of the paper machine and the application of the pinch former, the gap with foreign countries will be greater. The foreign paper machine flow system has developed rapidly. In addition to the above key equipment for slag removal, screening and degassing, which has good performance, high manufacturing accuracy and high degree of self-control, the dilution water sizing system has been widely used and equipped with DCS and QCS control systems (all domestic systems are supported by foreign countries). Foreign countries have recently developed a pressure mixer for the full mixing of slurry and concentrated white water. The degassing device uses a special pump to degass. The whole system is further developed in the direction of increasing sizing concentration, reducing white water return flow, shortening process, improving degassing efficiency and reducing unit production consumption
(13) paper machine
at present, domestic paper machines can basically meet the needs of most domestic paper mills, and can produce 150000 T/a carton board paper machine, 100000 t/a coated white board paper machine, 50000 T/a cultural paper machine and paper machine. The production capacity of paper machine has been greatly improved, and the domestic market share is high. Domestic paper machines with a width of 5.5m and a speed of 700m/min are in normal operation. However, in terms of technical performance and operation efficiency, domestic paper machines have high energy consumption, low operation efficiency, long commissioning cycle and poor operation reliability. There is still a significant gap between the main quality indicators of the produced paper and similar foreign products. Among them, the key technologies and equipment that play an important role in the main quality indicators of paper include: high-speed hydraulic headbox with dilution water, high concentration double-layer headbox, high-speed clip former, compound press with controllable medium and high rollers, shoe press, web stabilizer, soft calendering (super soft calendering), in-machine high-speed coating equipment, etc. all of which are imported from abroad
hydraulic headbox without dilution water, upper shaper, in-machine metering coating, vacuum suction dryer, cylinder winder with automatic roll change, and full-automatic rewinder have been successively operated in the transformation of various new and old paper machines, but the manufacturing quality is unstable, the operation reliability is poor, and the level of automatic control is limited. Compared with similar foreign products, there is still a certain gap. At present, no domestic paper machine with a speed of more than 1000m/min has been put into the market.
although the domestic demand for large-scale pulp machines and high-speed tissue paper machines equipped with high concentration headboxes, double forming and air cushion efficient drying is increasing, they are still all imported from abroad. The automatic control of the paper machine is constrained by the quality and accuracy of the measurement sensors. Automatic control is still a bottleneck problem in high-speed paper machines. In addition, the high-efficiency dehydration elements, high-speed polyester rollers, cordless paper guiding devices, arc rollers, steam joint devices, bearings, motors, reducers and other supporting components in the high-speed paper machine are still supported by foreign professional companies.
foreign countries have made great breakthroughs in the design concept of high-speed paper machines. It is not only the application of professional knowledge such as mechanical design and manufacturing technology, but also the application of scientific theories such as fluid mechanics and the practical results of experimental paper machines to the development of key technologies and equipment of paper machines by the most modern design means. The width of foreign paper machines has reached 10m, the maximum vehicle speed of the paper machine has reached 2200m/min, the maximum vehicle speed of corrugated raw paper machine has reached 1500m/min, the speed of high-grade vermicelli locomotive has reached 1300m/min, and the production capacity is more than 1000t/d. The newly developed in-machine coating and super calendering have been running normally on paper machines with a speed of more than 1200m/min. Large, high-speed, wide width and automatic paper machines have become the mainstream of the development of paper machines in the world today. The general trend of pulp and paper industry equipment is to use new technologies and processes to develop in the direction of energy conservation, consumption reduction, less pollution and no pollution. Pulping equipment is developing in the direction of large single machine capacity, small volume, high efficiency and high degree of automatic control. Papermaking equipment is developing towards large-scale, high-speed, wide width and automatic control.
3 thoughts on the development direction of China's pulp and paper equipment industry
paper industry equipment is one of the pillars of the paper industry to maintain high-speed development. During the "Eleventh Five Year Plan" period, with the transformation of the economic growth mode of the paper industry to quality and efficiency, the paper industry equipment must establish corresponding development ideas and develop in coordination and synchronization with the paper industry.
in view of the current situation of domestic pulp and paper equipment and the gap with the international advanced level, in order to further give play to the existing manufacturing advantages and certain technological advantages, we need to optimize the product structure in combination with the diversification of raw materials and market demand in China. With practical and efficient national production pulping and papermaking equipment and high-quality services, as well as professional division of labor and cooperation among industries, it can meet the market demand of various raw material pulping production lines with an annual output of 100000 ~ 300000 tons and various paper machines with a vehicle speed of 1000m/min and a width of 8m
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source: pulp and paper equipment branch of China Light Machinery Association Author: Zhang junnan