The twin roll press is the key equipment for black liquor extraction and pulp bleaching in the paper and pulp mill. The equipment integrates filtration dehydration, displacement washing and press dewatering. It has advantages of high washing efficiency, large production capacity and less washing water consumption, high pulp concentration, saving energy. With the development of the pulp and paper industry, the production capacity of the pulp line continues to increase, and the requirements for the production capacity of the twin roller press continue to increase. The twin roll press is the preferred washing equipment for large-scale paper pulping projects. CNBM has developed a new twin roll press that can be used for washing and concentrating various pulps such as chemical pulp, chemical pulp, and waste paper pulp.
How does twin roll press work?
The washing process of the twin roll press is divided into three zones of dewatering, displacement, and pressing. The pulp concentration is required to be 3.5% to 8%, and pulp is sent to the inlet on both sides of the washer by a low-concentration or medium-concentration pulp pump. The pulp is evenly distributed through the baffled pulp device, and the filter dehydration will be the first step after entering pulp tank., the dehydration process controls the pulp pressure in the tank to be in the range of 0.02-0.08 MPa, and the black liquor in the pulp enters the roller through the filter hole on the press roll surface, along the axial cone-shaped flow path and discharge from two ends of the roller, and a continuous and uniform pulp layer is formed on the surface of roller. As the press roll rotates to the replacement zone, the pulp concentration is about 10%, and the washing water is added to the replacement zone according to the dilution factor determined by the process. The pulp is subjected to displacement washing, and the washing water is also discharged through the pulp layer along the roller cone-shaped flow path, and the replacement washing is continued until the pulp entering the pressing zone, at the moment, the pulp enters the pressing zone between the two rolls, use the press to dewater and achieve a concentration of 25% to 35% that is required by the process, and then delivered to the next equipment by a broken screw installed on the top of the twin roll press.
The basic structure of twin rolls press
The twin roll press is driven by a hydraulic motor. The whole machine consists of the main part of the mechanical part and the main hydraulic system, auxiliary hydraulic system, and lubrication system. The main function of the main hydraulic system is to drive the rotation of the twin-roll press. The auxiliary hydraulic system squeezes the pulp and locks the grooved seal and lifts the tank body. The lubrication system is an important device that ensures the lubrication and maintenance of the high-load bearing of the equipment and efficient operation of equipment.
Process control points and parameters
The on and off of the twin roll press is very important. The parameter setting and automatic control of the main hydraulic system, lubrication system, and auxiliary system during the operation of the equipment are more important, which is directly related to the operation of the main equipment of the twin-roller. Reliability and safety
Advantages of twin roll press
- High-quality, cost-effective washing and dewatering equipment can effectively remove soluble solids in the pulp, especially the high COD removal rate, which can reduce the consumption of bleaching chemicals. The twin roll press has features of less washing water consumption, less wastewater consumption, high washing efficiency, and the amount of waste liquid produced by the tons of pulp is below 5 m3. After washing by the twin-roll press, the residual COD in the pulp is small and the pollution is small. At the same time, the COD in the washing wastewater of the bleaching section can be reduced, and the wastewater treatment cost can be reduced accordingly. The subsequent bleaching concentration is easy to control, and the amount of organic AOX entering the wastewater is small, which is beneficial to the bleaching system and the environment.
- The pulp concentration range is wide and the pulping concentration is high. The pulp concentration for extracting is 3%-5%, when it is used for the bleaching section, and the concentration of the pulp is 6%-10%; the concentration of the pulp is as high as 30%-40%, which is easy to meet the needs of medium and high-concentration beating, and is easy to realize the medium and high concentration transport and storage.
- It is easy to operate, start and maintain.
- The equipment is compact in structure, easy to install and operate, and has a small footprint, requires less space, and has low construction costs.
CNBM’s twin roll press integrated with machine, electricity and instrument integration is the largest washing machine with the highest single-machine capacity and low consumption and high efficiency in the world. CNBM is all involved in the design and development of the main equipment, unit control, and automatic control of the whole machine. The control system of the twin roll press is highly automated, and there is no need for manual intervention during the normal operation of the auxiliary, lubrication system and shut down equipment. Switching to AUTO mode, fully automatic control, which is superior to previous controls.
Besides, CNBM also supplies various paper pulp making machines, including digester, blow tank, vacuum drum washer, single screw press, gravity disc thickener, etc. Welcome to ask!
