What is a UHMWPE liner?

As the “gas cut” crisis intensifies, many European countries have turned their attention to coal, which was once planned to be phased out.

According to Reuters, on June 20, local time, the Dutch government said it planned to remove the output cap of coal-fired power plants in response to the energy crisis. In addition to the Netherlands, Germany, Italy, Austria, and other European countries are racing to find alternative energy sources and increase coal supply to deal with a possible energy crisis in winter.

One of the products that must be used in coal power production is called a UHMWPE liner. The following blog will introduce this product in detail, hoping to help customers who want to understand this product.

What is a UHMWPE liner?

The UHMWPE liner is a special product that can be used in coal bins, chutes, hoppers, silos, and conveyor systems widely. It is installed equipment inside the surface. Usually, we call it plastic liner, which means the plastic (UHMWPE) liner. UHMWPE material is the best type to be chosen for the liner. It can discharge the materials entirely and prevent the equipment from being cleaned. It can significantly improve work efficiency and reduce equipment maintenance costs. There will be no unclean discharge and material adhesion.

What material is the UHMWPE liner made of?

After a lot of research and experiments, it was finally decided to use the UHMWPE sheet as the lining of the coal bunker, using the self-lubrication and non-stickiness of the UHMWPE sheet to reduce the friction coefficient and solve the phenomenon of blocking the bunker. This product is called a coal bunker liner or UHMWPE liner.

Why use a UHMWPE liner?

Since coal bunkers in coal mines, power plants, and wharves are cast with concrete, their surface is not smooth, the coefficient of friction is large, and the water absorption is high, which are the main reasons for often bonding and blocking. Especially in the case of soft coal mining, more pulverized coal, and high moisture content, the blockage accident is particularly serious.

After many coal mines and power plants use a UHMW Polyethylene liner, it shows that it effectively solves the problem of silo blocking, and the effective utilization rate of the coal bunker is increased from 20%–50% to 100%, which avoids production interruption and stabbing caused by bunker blocking. Accidents, reduce the broken rate of warehouse materials, save the cost of clearing warehouses, greatly shorten the loading time, reduce the phenomenon of pressing the car skin, reduce the labor intensity of workers, and have significant social and economic benefits.

What are the consequences of coal bunker blockage?

Over the years, to solve the problem of bonding and blocking the warehouse, people have also thought of many methods: such as tiling tiles on the warehouse wall, laying steel plates, and hitting with air cannons or electric hammers, all of which have not been completely solved, and manual smashing of the coal bunker often occurs personal injury or death.

How to install UHMWPE liners?

Fix the large sheet material on the warehouse wall with shooting nails or screws, thus completely solving the problem of the coal bunker sticking and blocking. Generally, it is not necessary to cover the whole warehouse, as long as the coal discharge port part of the lower conical section of the coal bunker and the upper round warehouse part are lined with about 1 meter, the blockage of the warehouse can be solved.

What problems should be paid attention to when installing the UHMWPE liner?

When installing the coal bunker liner, in the case of large changes in operation or ambient temperature, the fixed form of the liner must consider its free expansion or contraction. Any fixing method should be designed to facilitate the flow of bulk materials, and the screw head is always embedded in the liner. For thicker liners, the seam should be cut at 45 degrees. In this way, variations in length are allowed, and a smooth plastic plane is formed in the silo, which is conducive to the flow of materials.
When installing the coal bunker lining, pay special attention to:
1. During the installation process, the plane of the bolt countersunk head of the lining plate must be lower than the plate surface;
2. During the installation of coal bunker lining products, there should be no less than 10 bolts per square meter;
3. The gap between each lining board should not be greater than 0.5cm (the installation should be adjusted according to the ambient temperature of the board).

What are the precautions for using UHMWPE liners?

1. For the first use, after the material in the silo is stored to two-thirds of the capacity of the entire silo, unload the material.
2. During operation, always keep the material in the silo at the material entering and unloading point, and always keep the material stored in the silo at more than half of the entire silo capacity.
3. It is strictly forbidden for the material to directly impact the lining.
4. The hardness particles of various materials are different. The material and flow rate should not be changed at will. If it needs to be changed, it should not be greater than 12% of the original design capacity. Any change in material or flow rate will affect the service life of the liner.
5. The ambient temperature should generally not be greater than 100 ℃.
6. Do not use external force to destroy its structure and lose fasteners at will.
7. The static state of the material in the warehouse should not exceed 36 hours (please do not stay in the warehouse for more viscous materials to prevent caking), and materials with a moisture content of less than 4% can appropriately extend the static time.
8. When the temperature is low, please pay attention to the static time of the material in the warehouse to avoid freezing blocks.

What is the role of coal bunker liners in coal power generation？

A coal bunker is an important part of the pulverizing system of coal-fired thermal power plants. In large and medium-sized power plants, most of the coal bunkers in the main powerhouse are made of section steel and steel plate. Because the material flows in the warehouse, the friction between it and the steel plate of the warehouse wall is easy to damage the wall, and the rough surface of the steel plate is easy to cause coal blocking. Therefore, in the design of the inner wall of the coal bunker, it is considered to add a layer of coal bunker lining plate with a smooth surface whose wear resistance is 5-6 times higher than that of ordinary steel plates, so as to prolong the service life of the coal bunker and reduce the maintenance rate. For a 600 MW unit, the coal bunker capacity in the main powerhouse is about 3 618 m3, and the surface area required for the lining is about 1122 m2. Another example is a 2×300 MW unit, the coal bunker capacity of the main powerhouse is about 3 228 m3, and the lining is about 3 228 m3. The surface area is about 1608 m2, and the engineering volume is large. If there is a large amount of falling off during operation, on the one hand, the base steel plate will lose its protection and accelerate wear and tear, and on the other hand, the fragments of the lining plate will block the discharge port of the coal bunker, causing the coal supply to be blocked. Overhaul not only affects normal production but also causes huge economic losses. It can be seen that the design and construction of the coal bunker lining plate are of great significance to ensure the safe operation of the unit.

To sum up, the UHMWPE liner plays a very important role in industrial production. It can greatly protect some mechanical parts, reduce maintenance costs, and improve production efficiency.

Related Reading： Tips for preventing UHMWPE liners from aging.