Parameter control of high efficiency powder separator

At present, the domestic high-efficiency powder separator mainly includes O-Sepa powder separator, combined powder separator, coal mill dynamic powder separator, K type powder separator, etc. However, due to the improper control of parameters in use, it is difficult for the high-efficiency powder separator to achieve the ideal effect. This paper mainly explains the problems that need to be paid attention to when using the high-efficiency powder separator from the engineering application point of view, in order to achieve the ideal powder selection effect.

（1）Air capacity control

Powder separator is a kind of air separation equipment, plays the role of gas-solid separation.Whether the air volume is appropriate, is the premise of powder separator to achieve good sorting effect. The air volume of the powder separator usually refers to the gas volume flow rate under the standard condition, and the feeding concentration is also the ratio of the feeding amount to the gas volume flow rate under the standard condition. However, with the gas volume flowmeter, when the gas density changes, the gas molecular weight becomes smaller, the actual material concentration value increases, which has an impact on the separation efficiency. Therefore, when expressing the ratio of material to gas, the ratio of the mass flow rate of the material and the mass flow rate of the gas should be used.

Most manufacturers think that the air volume on the drawing or selection manual is the working condition air volume, for example, when O-Sepa3000 is marked as 3000m3/min, in fact, it is only the air volume under the marked standard condition, that is, the standard gas volume flow rate is: QN=3000m3 /min ×60min/h=180000m3 / h.

The actual working temperature is 80 ~ 100℃, and it can be seen from the thermal expansion and cold contraction that the gas volume will expand, and the expansion amount can be easily calculated. At 80 ° C, without considering pressure loss:

Q=QN×(273+80)/273=232747m3/h

It can be seen that the influence of temperature on air volume reaches more than 29%, and the sensitivity of the powder separator to the volume flow of gas reaches about 1%. Therefore, when selecting the fan, the actual flow rate of the fan should be determined by calculation according to the actual working condition temperature used.

For a high altitude, the requirements of the classifier gas volume flow should be calibrated.The gas volume is related to the air pressure without considering the temperature variation in use. According to PlV1 / T1=P2V2/T2, assuming T1=T2, V2=P1V1/P2 is obtained, and the influence of pressure factors should also be taken into account when determining the fan.

（2）Rotational speed control

The separator is a quality control machine in the close-circuit grinding system, and it is an important auxiliary equipment.The selection of powder separator, the first is to determine the appropriate particle size of the finished product to meet the process requirements. For example, for cement, the selected process parameters should meet the specific surface area needs. Adjusting the speed of the separator is the most important way to change the fineness of the product, the higher the rotor speed, the finer the product fineness; The lower the speed, the thicker the product fineness.

For a factory's K3000-C high-efficiency powder separator, the relationship curve between the rotor edge linear speed and the finished product 30μm sieve residual value, ▲ indicates the specific surface area ①280m2 / kg, ▲②320m2 / kg, ▲③350m2 / kg, ▲④380m2 / kg, ▲⑤410m2 / kg.

It can be seen that when the rotor edge linear speed of the K-type powder separator is 22.2m/s, the specific surface area of the product is 320m2 / kg, and the specific surface area of the product is increased by 10m2 / kg for every 0.65m/s increase in the rotor edge linear speed. K3000-C separator rotor diameter is 2700mm, when the rotor speed is 189r/min, K3000C rotor edge linear speed Vr=2700mm×π×l89 / min=26.72m/s. According to the above data, when the speed of the K3000CK high-efficiency powder separator is 180r/min, the specific surface area of the product can reach 390m2 / kg.

Through the above calculation, the fineness of the product can be easily adjusted by adjusting the rotational speed. The same type of different specifications of the separator also has this relationship.

（3）circulating load ratio control

The circulating load ratio of the separator is one of the main factors affecting the power configuration of the separator.When the circulating load ratio is large, the power consumption of the separator is increased.Therefore,determining the reasonable circulating load ratio is the key factor to save energy and reduce consumption of the close-circuit grinding system. Before determining circulating load ratio, the production capacity of the powder separator should be determined.

The production capacity of the powder separator refers to the ability of the powder separator itself to process materials. It is different from the output of the grinding system, if the production capacity of the powder separator can not meet the system output requirements, it will affect the whole production. The production capacity of the high-efficiency powder separator can be simply calculated according to the following formula:

A=Ca·N·60·1／1000

Formula: A - the feeding capacity of the separator，t/h；

Ca-feeding concentration, kg/m3;

N - Ventilation volume of powder separator, m3 / min.

First of all, the feeding quantity required by the powder separator in the whole grinding system should be determined. The feeding amount is related to the circulating load ratio of the whole system. If circulating load ratio is large, the feeding capacity will be large, so the specifications of the matching separator will be larger.

The circulating load ratio of a grinding system depends on the length, diameter, internal structure, ball distribution and operation duty of the mill in addition to the performance of the powder separator, and more importantly on the specific surface area of the finished product.

Roller press combined with grinding system, the value can be reduced by 50% ~ l00%.