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Limestone Handling System

Our Limestone handling system has been widely used in Power plant sulphur removal projects,and we share almost 80% market in China,especially we are the supplier of the World First 600MW CFB Power Plant(Baima Sichuan Demonstration Power Plant ).

Changsha Shenxiang-Circulating Fluidized Bed (CFB) technology

Circulating Fluidized Bed (CFB) technology is a clean process for Fluidized Bed Combustors that removes up to 95% of pollutants, resulting in low emissions output.
Changsha shenxiang Universal Machine- ZMJ Column Mills (limestone mills) have proven to be very effective for direct-injection of dry sorbent lime or limestone into the CFB or combustion process. Our company almost share 80% market of sulphur removal projects in China.Our experience with CFB technology is extensive and dates back to the mid-1990s during the initial process development stages. These limestone grinding machines have proven themselves as an essential part of CFB systems.One of the most important factors influencing injection desulphurization effect in CFB furnace is the particle size of limestone. The particle size distribution of limestone plays a decisive role in desulphurization reaction, and also a big difficulty in the world.If the limestone particle size is too fine, it cannot have a circle flow and be utilized fully until to escape with the flue-gas; if the particle size is too large, the superficial reactant CaSO4 will prevent further inside reaction. Therefore, the particle size of limestone must be controlled strictly during desulphurization in circulating fluidized bed boiler.
Generally, the maximum particle size of limestone shall be required less than 0.7mm, 1.0mm and 1.5mm; the average particle size is required 0.25-0.45mm, and details shall be in compliance with the particle size distribution of boiler.

1.Introduction to grinding principle of ZMJ Column Mill



Being a vertical rolling mill with medium velocity and medium pressure, which is characterized by simple structure and lowest breakdown rate. 
The motor is set outside, connecting to the gear box and drive the main vertical shaft to rollers, the rollers make regular revolution and rotation.
Raw material from upper inlet is dropped into the gap between rollers and liners, forming a material layer. Meanwhile the material is rolled with pressure rock-on-rock, rolling pressure instead of  grinding. 
The finished product is finally discharge from beneath outlet, which size can be adjusted via gap distance and discharge pipe height. But the rollers never contact with liners. 

2.Introduction to powder preparation systems of ZMJ Column Mill and PL Air Classifier


The limestone will be processed into three stages:

In first stage is Raw material limestone conveying stage
The huge amount of limestone is usually supplied through truck and delivered in the storage yard.
The underground hopper is usually lay out in the storage yard too. And through the hopper and bucket elevator, the limestone will be carried to a buffer silo or directly to mill, which is depending on the storage situation of the raw material.

The second stage is Grinding & Separating stage
The material is passing through the belt weigher and metal detector, delivered to the core stage. It consists of the core equipment ZMJ column mill and PL classifier.
The material is feed in the ZMJ column mill, Being grinded and discharged, the material will be totally lift to the PL air classifier for separating, 
The coarse particles are discharged out the bottom and returned to mill to regrind; on the other side, the finished fines are carried by air out of the top of the classifier to the cyclonic collector.
Finally, the feed material is disengaged from the air stream and discharged out the bottom of the cyclonic separator into the finished product silo. 

The third stage is adding  another grade of separator
 (for required both the WFGD and injection furnace)
When both the WFGD and injection furnace are needed, an added SXZ high efficiency separator could be connect after the cyclonic separator, the SXZ high efficiency is specially for separating the finer powder(-325mesh) , which can achieve the application of  “one system two finished product”.

Advantages and parameters:
1.Particle size of products conforms to the distribution requirements raised by boiler factory, is not too coarse and ensures desulphurization efficiency;
2.The system has a large output; sectional particle size products are kept in grinding stage to the upmost extent; and separation efficiency is free from the impact from material humidity, particle size and shape etc.;
3.The whole system runs under the condition of negative pressure and no dust is produced;
4.Both equipment and system technology are mature and a large number of customers have verified the long-time trouble-free continuous running;
5.The service cycle of wearing parts of ZMJ Column Mill is longer than 3 years;
6.Calcium sulfur ratio is lower than actual powder consumption and 40-60% of powder consumption can be reduced actually every year;



 

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