This paper analyzes the process characteristics of coal slime dryer in China - Henan Hongxing

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The process characteristics of coal slime dryer at present in China are analyzed

A large amount of slime will be produced in the production process of modern coal preparation plant. The comprehensive utilization of coal slime is not only related to environmental protection, but also related to the economic benefits of enterprises. Therefore, the efficient recovery and utilization of slime has high value. The processing and utilization of slime is inseparable coal slime dryer This paper introduces the common coal slime drying in China.

 coal slime dryer

Domestic coal slime drying is mainly divided into high-temperature flue gas drying and low-temperature steam drying. At present, high-temperature flue gas drying is mostly used. High temperature flue gas is used to dry coal slime in rotary cylinder dryer. The application of low-temperature steam drying is less, but with the introduction of more stringent environmental protection and energy-saving measures, it will be more widely used.

High temperature flue gas drying

The high temperature flue gas coal slime drying system is mainly composed of heat source equipment (generally coal-fired hot blast stove), crushing silo, belt feeder, screw conveyor, rotary cylinder dryer, drive, unloader, induced draft fan, dust removal equipment and electric control system.

The specific drying process is shown in the following figure:

 High temperature flue gas drying process

Advantages of high temperature flue gas drying:

1. The high temperature hot air is in direct contact with coal slime, with high drying strength and high heat exchange efficiency.

2. It has high processing capacity, low fuel consumption and low drying cost.

3. It has strong overload resistance, stable operation and high reliability.

4. Convenient maintenance.

Disadvantages:

1. The high temperature hot air temperature can reach 500 ~ 700 ℃. When drying the coal slime with high volatile and high calorific value, if the operation is improper, there will be the danger of pulverized coal explosion.

2. The amount of dry tail gas is large and the dust content is high, so it is easy to cause environmental pollution if the treatment is not good.

3. The water in the evaporated slime is directly discharged, and the heat energy is not recovered, which is a great waste of heat and water resources.

Low temperature steam drying

Low temperature steam drying is an energy-saving and environmental protection method which uses latent heat of vaporization of waste heat steam in power plant to heat and dry coal slime. The water evaporated from coal slime can be recycled by heat exchanger. The drying system is mainly composed of beating bin, belt feeder, screw conveyor, steam drying equipment, transmission, unloader, induced draft fan, dust removal equipment and electric control system.

The specific drying process is shown in the following figure:

 Low temperature steam drying process

Advantages of low temperature steam drying:

1. Using low-pressure waste heat steam of power plant as heat source has low temperature, intrinsically safe system and no dust explosion danger.

2. Less steam consumption, dry.

3. The steam that has finished the work is condensed into water, which can be used as boiler return water after simple treatment.

4. The water and heat evaporated after coal slime drying can be recycled.

The amount of dry tail gas is small, the dust content is low, it is easy to be treated and can meet the discharge standard.

Disadvantages:

1. Low temperature heating is a kind of drying in recent years. At present, the equipment is not perfect, and the initial investment is too high.

2. The small processing capacity is the bottleneck of its popularization and application.

Steam rotary dryer

Steam rotary dryer is a kind of mature drying equipment in China. According to the different structure, it can be divided into straight pipe fixed steam rotary dryer and ring pipe split type steam rotary dryer.

The straight pipe fixed steam rotary dryer has the following characteristics:

1. Mature, relatively fixed structure.

2. The structure of heat exchange tube is simple, and it is fixed on the end plate of steam chamber by welding, so it is difficult to repair or replace.

3. The heat exchange tube spacing is not adjustable, so it is impossible to set different tube spacing according to the fluidity of materials at different positions of the equipment.

4. The equipment has large volume, large weight, large floor area and high investment cost of plant and foundation.

The ring pipe split type steam rotary dryer has the following characteristics:

1. The loop pipe is mainly heated. There are many tubes in the unit volume, the heat exchange surface is large, and the effective utilization rate of heat exchange surface is high.

2. The structure of heat exchange tube is simple, and the heat exchange tube is detachable structure, which is convenient for maintenance and replacement.

3. The tube spacing of the heat exchange tube is set flexibly, the material fluidity problem, and the blockage phenomenon is prevented.

4. The material contact heat transfer along the flow reduces the wear of the material to the heat exchange tube, and improves the service life of the heat exchange tube.

With the increasingly strict national environmental protection and energy-saving policies, high-temperature flue gas drying has become more and more unsuitable for the needs of domestic coal slime drying market due to its own shortcomings. At the same time, energy-saving, environmental protection and intrinsic safety of low-temperature steam drying began to get more promotion and application. The ring pipe split type dryer in the main equipment of low-temperature steam drying will occupy more market share because of its advantages of convenient maintenance and replacement, good wear resistance and low overall investment. Our company according to the creation of a variety of drying equipment by the user's favorite, a variety of The model and specification of slime dryer are complete I welcome to consult our company.

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