Search

Powder Fluidization and Processing

Introduction

 Transportation of pulverized coal is a difficult process because ultra-fine coal powder is easy to bridge, agglomerate, or channel. The solution is to make it homogenously fluidized. So, what are the process details, and what is the pulverized coal anyway?

If you are curious to know about it, you are at the right place. Let’s know them in detail.

Sintered Metal Filter Elements, Filtration System Solutions

What is Powder Fluidization and Processing?

Fluidization is a highly effective method for handling fine bulk material in a liquid-like condition. Different pulverized coal gasification, fuel handling, and other industries use micron-sized coal powder under high-temperature conditions.

But to smoothly transport these coal powders to the high-pressure gasifier is difficult; because they are easy to form agglomeration or bridging during transportation.

The powder fluidization method is used to make coal powder homogenously fluidized in the process of conveying. Air or another gas is used for powder fluidization and processing to make it a fully fluidized state or only in a localized manner (small amount of gas flow).

Fluidization and Its Types

Fluidization is a process (similar to liquefaction) to keep solid particles floating in an upward direction by maintaining the flow of gas or liquid. In short, fluidization is used to process fine solids into a fluid-like state when it is transferred to the high-pressure gasifier.

However, fluidization refers to those liquid-solid systems where the solid phase behaves like a fluid by the upwelling liquid stream or others. There are different types of fluidization used in different industries:

Homogeneous or Particulate

Homogeneous or heterogeneous fluidization dispersed solid particles evenly in the fluid material without creating any observable bubbles. Most of the liquid fluidized beds are considered homogeneous. However, in the gas-solid system, these fluidization regimes are more complex to create.

Bubbling or Aggregative

When the gas velocity is increased than the minimum bubbling velocity, aggregative fluidization appears in the form of bubbles. And the first creating bubble velocity is known as the minimum bubbling velocity, which is occurred in the gas-solid fluidized system.

Slugging

In this gas-fluidized regime stage, the bubbles grow larger, and the velocity is increased with a high ratio of height to diameter. Also the stage is also known as the transition of bubbling size in fluidization. When gas velocity is increased, the regimes will change to turbulent ones.

Turbulent

When the bubble breakup increases for the improved mass transfer characteristics, turbulent fluidization occurs. To operate or successfully do the fluidization, both fluidization velocity and permeation gas velocity are increased. But the bed mass and the membrane area remain the same as before, just like the slugging fluidization stage.

Jetting

It is a bubbling fluidized bed equipped in the upper part of the bed. That means it is a control loop and fluidization quality analyzer that is responsible for measuring the pressure drop and time for a fluidized bed. Here, the gas is passed to the fluidized bed through a vertical pipe, creating a jet-fountain zone.

Spouting

In this fluidization process, the fluid is vertically introduced upwards at a suitable velocity. It is vastly used in the gas-solid contact technique in the fuel reactor to ensure proper operation. That means a spouted bed is used as an alternative process to a fluidized bed.

What is Pulverized Coal?

Pulverized coal is a raw material and dust form of coal. And pulverization is a method of crushing to make coal into ultra-fine coal powder that enables it to burn like a gas which is more efficient combustion. And combustion is used mainly in different power stations to increase steam generators.  

Types of Pulverized Coal

Types of pulverized coal firing systems depend on power plants’ raw materials and other criteria. But the most common and effective firing systems are:

Unit System or Direct System

The raw coal is stored in the feeder from the coal bunker, and hot air is used to dry the coal. After that, it is transferred to the pulverizing mill to complete the pulverized process.

The mixer of pulverized coal and primary air flows to the burner. And then, their secondary air is added to complete the overall process.

Bin or Central System

To dry the processed coal, it is transferred to the dryer, and this dryer is used for waste flue gases, preheated air, or bleeder steam that works as a drying agent. After completing the process, the dry coal is then transferred to the pulverizing mill to the pulverized coal bunker (bin).  

A cyclone separator is used to separate the transporting air from the dry coal. At the feeder, primary air is mixed, and the overall coal mixer is supplied to the burner.

Semi-Direct Firing System

In this system, to separate the conveying medium from the coal, a cyclone separator is applied between the pulverizer and furnace. After that, hot primary air is supplied to push the coal particles from the cyclone into the furnace by falling by gravity.

How Does Pulverizing Plant Work?

The basic function of the pulverizer is to break down and crush the coal lumps into ultra-fine coal powder before it is transferred to the boiler. Here, ultra-fine coal is used as a fuel that reduces coal-based thermal power plant costs. Now, it’s time to explore how these powerful plants handle the coal pulverizing process successfully.

First, the coal is imported from the supply chain to storage. After that, the coal is unloaded either manually or using wagon tipplers. To process those coal cubes, there are different types of equipment used, like –

Pull Chord Switch

A switch series are arranged on the side of the conveyor belt to ensure the power supply to the rotor of the conveyor belt.

Vibrating Feeder

The coal is stored in a huge hub on the belt through vibrations. And the vibrations are created by this vibrating feeder.

Flap Gates

These gates are used to channel the route of coal or segment coal to another belt for broken coal. There are two gates that help to complete the operation: an open gate that lets coal pass and a closed gate that stop movement.

Magnetic Separator

The separator is used to separate the ferrous impurities from the coal cubes.

Metal Detector

The transmitter consists of a high-frequency oscillator used to produce 1500Hz at 15V (oscillations). If any metal is found in the coal, the receiver can detect it by this frequency signal. After that, a tripping signal is sent to stop the conveyor belt.

Belt Weightier

It is used on the belt carrying coal and used to release the tension on the belt.

Reclaim Hopper

The reclamation process help to take coal from the dead storage to reclaim hoppers for coal preparation. And the whole process is done by belt conveyors.

Second, the processed or crushed coal is supplied to the furnace through coal pipes (hot and cold air mixture pipes). Here, the boiler is used to prevent deformation while conveying the pulverized coal to very high temperatures.

Also, any unburnt coal particles in the middle of the processing are collected and, again, it is processed.

Pulverized Coal Gasification – What is it?

Coal gasification is the process of turning coal into hydrogen. The gasification process works when the coal is mixed with oxygen, air, or steam at a very high temperature. During this process, combustion doesn’t occur.  

The Gasification Process

First step: Under extreme hit, the gasification process converts the coal into synthesis gas (also called syngas). It is a mixture of carbon monoxide, carbon dioxide, hydrogen, and a tiny amount of other gases and particles.

Second step: The mixture of syngas is then set to cool down. Then it proceeds to the cleaning step. At this step, all the particles and other gases, such as mercury, sulfur, contaminants, etc., are removed except for carbon dioxide, carbon monoxide, and hydrogen.

Third step: Now, the cleansed syngas is sent to a shift reactor. This is where the major change occurs. By mixing with steam, the carbon monoxide is turned into hydrogen and carbon dioxide. At this point, the syngas is no longer a mixture of 3 components; rather, it is all about Hydrogen and Carbon dioxide.

Fourth step: At this stage, the syngas is separated. Meaning that hydrogen and carbon dioxide no longer stays together as syngas. The carbon dioxide is kept for sequestration. And the hydrogen is cleaned once again, after which it is ready for a variety of uses, such as it can be burned for generating electricity, used as a fuel for an internal combustion engine, a chemical for fertilizing making, and many more.   

Benefits

The benefits of pulverized coal are:

  • Increases the efficiency of used boilers
  • Helps reduce the steam temperature time
  • Increases the efficiency of coal usage variety  
  • Enables releasing a large amount of heat
  • Assists occurring successful combustion and increasing combustion rate
  • Pulverized coal combustion can be used in an automatic control system  

Application

The powder fluidization process is the most crucial method in different power plants. Here, pulverized coal is used as raw materials. The application of this process is mentioned below:

Energy generation

Pulverized coal or powdered coal is used in fossil fuel power plants for generating electricity.

Thermal power plants

Pulverized coal is used for generating thermal energy. For this purpose, a pulverized coal-fired boiler burns the pulverized coal and generates this energy.

Coal-water slurry fuel

Pulverized coal is used for making slurry by mixing it with water. This liquid mix is burned in a boiler that burns oil.

Gasification

Carbon monoxide, methane, and hydrogen-like gases can be obtained using the gasification process.

Shinkai Powder Fluidization and Processing Description

At ShinkaiFilter, highly trained engineers have researched for years and developed a complete set of pulverized coal conveying systems. This system includes inflatable cones, inflatable flutes, pipeline inflators, etc.

This advanced-level pulverized coal conveyancing system is designed to address stable transportation of ultra-coal. Many industrial and manufacturing companies worldwide are using the pulverized coal conveying equipment Shinkai has developed. Recently, the silicon industry and catalyst production are also utilizing this system from Shinkai to transport ultra-fine powder.  

So, if you need this system to convey ultra-fine powder for your industry, contact us to discuss your needs and provide the best solution. What’s more, we can custom-develop the full-process solution for you, including fluidization element design, selection, process design, valve and instrument selection, piping design, and many more.

Case Studies

Here at ShinkaiFilter, our expert engineers continuously research and develop products so that industrial procedures can run without a hitch. Our team of professionals is working relentlessly to improve the quality of products and offering custom solutions so that clients can access some of the most advanced technological solutions.

On that note, here are some of the case studies from our clients who benefit from our powder fluidization and processing system.

Case study 1: A gas distribution control company was having trouble with hydrogen. As you already know, it is the largest source of pulverized coal gasification. They needed a solution that would smoothly transport the micron-sized coal powder. They reached out to us with that specific need. We listened to their requirement and incorporated our skills to develop their requirement-specific powder fluidization and processing system. Guess what? This newly developed system smoothen their transportation without affecting the material.  

Case study 2: A powder material transmission company in Japan reached out as they could not solve conveying ultra-fine coal powder, as this material is easily prone to agglomeration, bridging, and channelling. But their clients want fluidization elements that are made of the sintered plate.

We collaborated to devise a solution for them that would solve their problem. We developed a set of pulverized coal conveying systems for them. Our advanced-level solution complied well with their manufacturing system, and they got to solve their problems.

Now that you know that we can solve any of the powder fluidization issues your industry is facing, reach us for your need so that we can quickly solve your problem.

Conclusion

Powder fluidization and processing are crucial for transporting ultra-fine coal to the high-pressure gasifier. Here, the most challenging part is maintaining the coal’s homogeneous fluidization state. Shinkai’s expert engineering team has developed a complete set of pulverized coal transferring systems applied in any coal gasification plant worldwide.

Why are you waiting? Feel free to contact us. With us, you get customizable and cost-effective fluidization products.

Contact
Get a quote Ask an engineer Customer service