Separation Equipment for Thermal Power Plants Powder Separators

Patent for utility model: ZL 201920688600.x.
Coarse powder separator

One.summary
    The coarse powder separator is one of the key equipment of the storage pulverizing system in the steel ball mill, and its operation performance has a great influence on the operation and efficiency of the boiler. At present, the UKKB radial baffle coarse powder separator used in most old power plants, due to the inherent limitation of structural form and the problem of design and lectotype, has exposed some problems in its operation, such as insufficient pulverizing output, too coarse pulverized coal, poor uniformity, large resistance, serious wear and high power consumption, which directly affects the economy and reliability of the boiler and even the whole unit.
    Based on abundant field tests and sufficient laboratory research, our company has developed a series of new coarse powder separators of SZCF type.
    At present, it belongs to the latest type in China. After practical test, the advantages of this new type of biaxial multi-channel coarse powder separator are: excellent separation performance, low fineness of pulverized coal, good regulation performance, low resistance, high efficiency, and suitable for large air volume operation, thus improving the output of coal mill, reducing unit power consumption and improving the combustion efficiency of boiler.

 

Three.design feature

1.Structural characteristics of radial and old axial separators
   (1).When the pulverized coal gas enters the separator, it is blocked head-on by the impact cone at the lower part of the inner cone, which makes the gas flow bend, so that a uniform flow field cannot be formed between the inner cone and the outer cone, and a layer of high-speed gas flow is formed near the inner wall of the outer cone, which is not conducive to the gravity separation at the lower part. Although the airflow at the entrance is impacted, which slows down the speed of some coarse particles, because of the high speed of the airflow at the entrance, the particles that are bumped back are picked up by the high-speed airflow. Also, due to the airflow deflected by the impinging cone, the particles separated from the inner cone for the second time are lifted up again at the outlet of the inner cone, forming an ineffective circulation in the separator.
   (2)Due to the bending action of the impact cone, the inner wall of the lower cone at the same horizontal position with the impact cone is seriously worn, and powder leakage often occurs.
   (3)The air lock between the inner cone and the impact cone is often stuck, so that the wind powder is led out by this short circuit, and the separation effect is extremely poor.
   (4)Due to the structural limitations of the radial coarse powder separator, the primary separation in the lower part is not sufficient, and the tertiary separation mainly based on centrifugal and inertial separation at the outlet can not achieve good separation effect. In addition, the outlet pipe is very close to the radial blades, and the diversion and suction of the outlet affect the formation of the rotating separation field, and some particles even flow into the outlet pipe because of short circuit, so the separation effect is not ideal.
   (5)The flow resistance of radial coarse powder separation is large.
       These structural characteristics of radial coarse powder separator make the flow field distribution and separation mechanism unreasonable, and have repeatedly shown disadvantages in years of operation practice, which urgently needs upgrading or technical transformation.

 

2.Structural characteristics of a new dual-axial multi-channel coarse powder separator;
   (1)The flared pipe is adopted at the inlet pipe, so that the airflow speed reaches a reasonable velocity (about 17m/s), which is beneficial to the primary separation (gravity separation) of the lower part of the separator.
   (2)Cancel the radial baffle and close the inner cone. Because the lower part of the inner cone is an inverted triangular cone, the flow field distribution in the lower part of the inner cone is improved, the flow field distribution is uniform, the average speed of the air flow is low, and the gravity separation effect is enhanced.
   (3)Between the upper inner cylinder and the outer cylinder, a double sleeve baffle is installed, and the multi-channel impact and inertia separation are formed due to its stabbing and bending effects on the airflow. In addition, the flow velocity here is relatively low, and the separation effect is obvious.
   (4)Due to the guidance of the axial baffle, the axial rotating flow field is formed in the upper space of the separator.  The gas-powder two-phase flow is fully separated (centrifugally separated) for three times here because of the large upper space.
   (5)The inner cone is closed, which prevents short circuit of airflow. The flow field is evenly distributed, the average speed is reduced, and the wear of the lower cylinder is greatly reduced by installing an anti-wear material sleeve.
   (6)With the increase of outlet pipe diameter, the wear of upper part and outlet pipe is reduced. The upper outlet is equipped with swirl guide vanes, which greatly reduces the flow resistance.