Coarse powder separator

1、 Overview of coarse powder separator:
A semi industrial model test was conducted for the utilization of auxiliary equipment in Lianyungang Huaneng Power Plant. The airflow pattern inside the coarse powder separator, especially in the primary separation zone, was carefully measured. Through experimental research on separator models with different structural parameters, a new type of series biaxial coarse powder separator was developed, achieving the optimal design of the series biaxial coarse powder separator. The coarse powder separator is one of the key components of the intermediate storage powder system. Due to the limitations of the separator structure, many old power plants have problems such as high resistance, coarse fineness, severe local wear, poor uniformity, and insufficient output. Further improving the performance of the coarse powder separator, reducing its local wear, and increasing the volumetric utilization rate of the axial coarse powder separator, this technology has passed the industrial key science and technology project appraisal meeting and received high praise from the appraisal committee. It is unanimously agreed that the structure of the series biaxial coarse powder separator is reasonable, with excellent performance, improving the uniformity of coal powder, facilitating the combustion and burnout of coal powder particles in the furnace, and improving the economic efficiency of the powder production system and boiler unit operation. This technology has significant economic benefits and important promotion and application value.  

2、 Technical characteristics of coarse powder separator:
1. Structural characteristics of radial and old-fashioned axial separators
(1) When the coal powder airflow enters the separator, it is blocked by the impact cone at the lower part of the inner cone, causing the airflow to bend and unable to form a uniform flow field between the inner and outer cones. A layer of high-speed airflow is formed near the inner wall of the outer cone, which is not conducive to gravity separation at the lower part. Although the airflow at the inlet is impacted, causing a decrease in the velocity of some coarse particles, the particles that are hit back are carried up by the high-speed airflow due to the higher velocity of the inlet airflow. Due to the airflow deflected by the impact cone, the particles separated twice inside the inner cone are lifted again at the outlet of the inner cone, forming an ineffective circulation inside the separator.
(2) Due to the bending effect of the impact cone, the inner wall of the lower cone at the same horizontal position as the impact cone is severely worn, and powder leakage often occurs.
(3) The air lock between the inner cone and the impact cone often gets stuck, causing the wind powder to be discharged through short circuits and resulting in extremely poor separation efficiency.
(4) Due to the structural limitations of the radial coarse powder separator, the primary separation at the lower part is not sufficient, and relying solely on centrifugal and inertial separation at the outlet cannot achieve good separation results. In addition, the outlet pipe is very close to the radial blades, and the guiding and suction effects of the outlet affect the formation of the rotating separation field. Some particles even short-circuit and flow into the outlet pipe, resulting in unsatisfactory separation effect.
(5) The flow resistance of radial coarse powder separation is relatively high.
The structural characteristics of the radial coarse powder separator result in an unreasonable flow field distribution and separation mechanism, which have repeatedly shown drawbacks in years of operation and urgently require upgrading or technological transformation.   

2. Structural characteristics of the new dual axis multi-channel coarse powder separator:
(1) The inlet pipe adopts a flared pipe to achieve a reasonable airflow velocity (about 17m/S). Beneficial for the primary separation of the lower part of the separator (gravity separation)
(2) Cancel the radial baffle and seal the inner cone. Due to the fact that the lower part of the inner cone is an inverted triangular cone, the distribution of the airflow field in the lower part is improved, the flow field distribution is uniform, the average velocity of the airflow is lower, and the gravity separation effect is enhanced.
(3) A biaxial baffle is installed between the upper inner and outer cylinder bodies, and the multi-channel system forms an impact and inertial separation due to its impact and bending effects on the airflow. Moreover, the flow velocity here is relatively low, resulting in a significant separation effect.
(4) Due to the guidance of the axial baffle, an axial rotating flow field is formed in the upper space of the separator. Due to the large space in the upper part, the two-phase flow of gas and powder undergoes sufficient tertiary separation (centrifugal separation) here.
(5) The inner cone is sealed to prevent airflow short circuits. The flow field distribution is uniform, the average velocity is reduced, and the installation of wear-resistant lining on the lower cylinder greatly reduces wear.
(6) The increase in outlet diameter reduces wear on the upper and outlet pipes. Installing swirl guide vanes at the upper outlet significantly reduces flow resistance.

3、 Working principle of coarse powder separator:
From the working principle of the coarse powder separator, the original axial coarse powder separator has similar gravity and impact separation effects in the primary separation zone as the radial coarse powder separator. However, in the axial adjustment baffle zone between the inner and outer cones, coarse particles collide with the axial baffle and are bounced back, increasing the effective impact separation effect by one stage; Simultaneously arranged in the annular channel between the inner and outer cones, the axial adjustment baffle improves the centrifugal separation effect in the separation zone and enhances the performance of the separator. The series biaxial coarse powder separator is based on the original axial coarse powder separator, which improves the structure and airflow morphology of its primary separation zone by adding a first stage axial adjustment baffle for impact separation in the primary separation zone, enhancing the separation efficiency of the coarse powder separator and improving the uniformity of coal powder.     

4、 Performance characteristics:
1. The lower cone and outlet pipe diameter of the radial coarse powder separator are severely worn, while the wear of the axial components produced by Huaneng Electric Power is significantly reduced.    

2. The internal structure is simple, safe and reliable, with flexible adjustment and a wide range of adjustments.
3. The dual axis multi-channel produced by Huaneng has a reduced resistance of about 400Pa compared to the radial type, which increases the ventilation volume of the powder production system.
4. After the dual axis multi-channel operation or technological transformation produced by Huaneng, it has been tested by the pilot plant and can increase the output of the powder production system by 25%, reduce the power consumption of the powder production system by 15% (about 4.3kwh/t), and reduce the fineness of coal powder by about 10%. The efficiency of dual axis multi-channel has increased from 33.8% to 52%, and the cycle rate has decreased. The uniformity of coal powder has also been significantly improved.
5. Due to the significant reduction in coal powder fineness (R90C), it is very beneficial for stable combustion and reducing combustion losses, which will greatly improve the combustion efficiency of the boiler.

5、 Specification and model of coarse powder separator:

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