1. Type of screening equipment
The three most common types of screening equipment used in solid waste treatment are fixed screens, vibrating screens and trommel screens.
①Fixed screen
The screen surface is composed of many screen bars arranged in parallel and can be installed horizontally or tilted. It is characterized by simple structure, no power consumption, low equipment cost and easy maintenance, so it is widely used in solid waste sorting. Fixed screens can be divided into two types: grid screens and rod screens.
The grating screen is generally installed in front of the coarse crusher, and its function is to ensure that the human material has suitable grain size.
The rod screen is suitable for screening granular waste with a particle size greater than 50mm. It is generally used before coarse crushing and medium crushing. When installed, the inclination angle should be greater than the friction angle of the waste to the screen surface, generally 30°-35°, to ensure that the material moves along the The screen surface slides down. The screen hole size of the rod screen is 1.1-1.2 times the particle size of the materials required to be screened, and the width of the screen bars should be greater than 2.5 times the largest particle size in solid waste.
②Vibrating screen
Vibrating screen is a piece of equipment widely used in many industrial sectors. Its characteristics are that the vibration direction is perpendicular or approximately perpendicular to the screen surface, the vibration frequency is 600-3600r/min, and the amplitude is 0.5-1.5mm. The material segregates on the screen surface. The particles with high density and small skin pass through the gaps between the particles with low density and large size, enter the lower layer and reach the screen surface. The suitable inclination angle of the vibrating screen is generally 8°-40°. An inclination angle that is too small will cause the material to move slowly, resulting in a reduction in screening efficiency per unit time, but an inclination angle that is too large will cause the material to move too fast on the screen surface, so that materials with high density and small particle size are often discharged before they are fully screened. outside the screen, resulting in reduced screening efficiency.
Due to the strong vibration of the screen surface, the vibrating screen eliminates the phenomenon of blocking the screen holes, which is beneficial to the screening of wet materials, and can be used to screen coarse, medium and fine particles of construction waste. There are two main types of vibrating screens: resonance screens and inertial vibrating screens.
③Trolley screen
Also known as the rotary drum screen, it is a cylindrical screening surface that rotates slowly (generally the speed is controlled at 10-15r/min). The screen drum axis inclination angle is generally installed at 3°-5°. The most commonly used screen surface is the impact screen plate, which can also be a screen mesh woven from various materials, but the screen surface is not suitable for screening linear materials.
(2)Application of screening equipment
The following factors should be considered when selecting application screening equipment:
①Particle size, shape, PSD, overall density, moisture content, possibility of drowning or entanglement;
② The construction materials of the screener, the size and shape of the screen holes, the proportion of the screen holes in the screen surface, the rotation speed, length and diameter of the rotary screen, the vibration frequency, length and width of the vibrating screen;
③Screening efficiency and overall effect requirements;
④Operating characteristics, such as energy consumption, daily maintenance, difficulty in operation, reliable parts, noise, abnormal vibration power and possibility of blockage, etc.
