Introduce

In coking coal blending, the fineness of coal blending has a significant impact on the quality of coke. In recent years, with the in-depth research on the influence of coal blending fineness on the quality of coking coke, it has been known that the increase of overly fine components caused by excessive crushing has a deteriorating effect on the quality of coke.

Therefore, effectively reducing overly fine components is one of the research directions for improving the quality of coke in the production of coking coal blending. As a screening device that effectively reduces excessive crushing, the development and application of roller screen have always been an important way to solve the problem of coal blending in coking.

Roller screen

The sieve surface of the Roller screen is composed of multiple sets of sieve shafts rotating in the same direction. Several equally spaced sieve plates are installed on each sieve shaft. The sieve plates on adjacent sieve shafts are arranged in a cross pattern. A mud scraper is provided below the sieve plates to clean the sticky particles, ensuring the permeability of the sieve holes during the screening process.

During the rolling process, the material continuously stratifies. Small particles move down while large ones roll forward. The screen plates on the adjacent screen shafts in front and behind form a cross and interlaced movement, thus creating rectangular dynamic screen holes that interlock and cross. Meanwhile, a scraper is installed at the lower part of the screen surface to self-clean the sticky material.

Problems and solutions in the Roller screen application

Material blockage

① The chute is clogged. The interface between the Roller screen and the crusher is relatively narrow compared to the ordinary chute. Coupled with the fact that the transported coal material is viscous, it is certain to cause blockage. This issue can be eliminated from the initial design perspective. It can be addressed by lining with smooth and wear-resistant materials such as stainless steel plates. Finally, it can also be resolved by adding a vibration motor for forced vibration.

② The scraper is clogged. Due to the stickiness of coal materials and the high moisture content of incoming coal, it may cause difficulties in material adhesion on the scraper and material sticking. This issue can be resolved by initially designing adjustable screen holes and other angles.

Dust raising

The materials on the screen of the Roller screen enter the crusher through the connected chute. Due to the high-speed rotation of the crusher, a relatively high air pressure is formed inside, which inevitably leads to the lifting of the finer coal powder. The problem of dust can be solved by adding dust removal points to the upper cover part of the roller screen during the initial design.

Uniform fabric

At present, the fabric part of roller screen is a set of common Angle steels installed in the feeding chute of roller screen, and the installation method is welding. There may be problems such as the weld joint being prone to cracking and falling off. Meanwhile, as the coal material adheres and sticks, the uniformity of the material distribution will deteriorate. It is possible to consider using special wear-resistant and corrosion-resistant materials instead of the distributor.

Screening efficiency

At present, the screening efficiency of roller screen can reach more than 60%, but it is greatly affected by the moisture and adhesiveness of the materials. If a high screening efficiency is to be maintained, the determination of the screen hole size during the design process is particularly important, and at the same time, the role of the scraper cannot be ignored.

Manufacturing and installation accuracy

According to the current usage situation and the working principle and equipment structure of roller screen, it is determined that the manufacturing and installation accuracy of roller screen has a huge impact on its screening effect and normal operation. Especially with factors such as the reduction of the sieve holes of the roller screen, the refinement of the particles of the screened materials, and the increase of viscosity and moisture, higher requirements are placed on the manufacturing and installation accuracy.

Maintenance

According to the equipment structure of roller screen, roller screen has the characteristics of many moving points, many disassembly and installation points, and high requirements for installation accuracy, which determines that its maintenance is complex and time-consuming. Especially for the maintenance or replacement of the roller screen screen, spare parts need to be prepared in advance and the entire shaft should be prepared.

Analysis of Application Prospects

The structure of the equipment is simple

The rollers of the Roller screen are inclined and arranged relatively independently. Each roller has a single drive and operates independently. The single-roller screen plates are firmly installed. The values of the roller shaft diameter and screen plate thickness ensure the rigidity of the roller shaft and the screen plate gap. The scraper plates are firmly installed. The whole machine is sealed. All components are clearly visible. The equipment has a simple structure and prominent features.

The screening effect is remarkable

The dynamic arrangement of the screen holes along the direction of the coal material flow causes the coal flow to be conveyed by the power of the screen shaft and stirred at the same time. Fine coal particles are separated and fall along the screen holes under the action of gravity, centrifugal force and friction to achieve screening. Thorough stirring and carrying contribute to the stability of the screening effect.

The relative movement of large and small coal particles in the space between the screen plates has a significant cleaning effect on the surface of the screen plates. The auxiliary scraper effectively cleans the adhered coal on the screen shaft and screen plates, ensuring the stable operation of the equipment and the normal screening process. The above elements determine the characteristics of the roller screen's applicability for screening viscous coal materials and solve the clogging problem of traditional screening equipment.

The equipment has a low failure rate

The simple and sturdy equipment structure has a buffering effect on the impact of coal flow. The reasonable power configuration and inclination Angle can control the speed of coal flow, distribute the material load inside the screen machine and control the wear rate of the screen plates. The low load of the power unit determines that the failure rate of the power part is correspondingly reduced. The low wear rate of the screen plates, screen shafts and guard plates, which are in contact with the materials inside the screen machine, also determines that the failure rate of the equipment is correspondingly reduced. Further performance improvements of worn materials have a positive effect on extending the service life of equipment.

The overall failure rate of the machine has been reduced, enhancing the safety and reliability coefficient of the equipment, and lowering the intensity and cost of equipment maintenance and repair. The components of Roller screen are relatively lightweight and easy to maintain.

The screening and crushing of the Roller screen combined crusher, compared with the screening and crushing of a single crusher, has a lower comprehensive energy consumption under the same coal processing capacity, which can play an energy-saving role.

The screening and crushing of the Roller screen combined crusher has solved the long-standing problem of excessive crushing of coking coal blending, which is of great significance for improving the quality of coke and enhancing the working environment.

Summary

To sum up, the operation, screening, power saving, maintenance, high efficiency and economy of roller screen have broad application prospects for solving the problem of excessive pulverization of coking coal blending.