Pellet mill produces strange sound and shakes seriously

Q: When ring die pellet mill produces strange sound and shakes seriously, what’s the problem and how to fix it?

Making Pelelts with Ring Die Pellet Mill

a.Single Roller Ring Die Pellet Mill    b.Double Roller Ring Die Pellet Maker
c.Triple Roller Ring Die Pellet Machine

1. Scraper  2. Roller  3. Ring Die  4. Biomass Materials

A: There are several reasons to this situation:

1. The conveying speed of raw material is not stable. You should adjust the feeding speed.
2. The deflection scraper is wearing out making the feeding speed fluctuation. You should replace it with a new one.
3. Among the ring die and the roller, one is new and the other is old. This combination should be avoided. It is better to use new ring die with new roller.
4. The distance between the ring die and roller doesn’t match with the raw material. Try to adjust the distance and make the machine running smoothly.
5. The roller of the pellet machine is wearing out.
6. The raw material is difficult to be pelletized. Make some appropriate adjustments to the material.
7. The steam supply is insufficient or the pressure is waving. Check the steam pipe, pressure system and reducing valve. Make sure they are normal.
8. Impurities are mixed into the machine chamber.
9. The spindle bearing is wearing out or damaged and needs to be replaced.

Discussion about pellet fuel industry

Why pellet fuel didn’t get widespread application? The reason is more than just technical defects. The Second Oil Crisis brought worldwide panic about energy resources. Many developed countries began the research of energy-saving technology and looking for oil fuel alternative. At that time, solar energy, wind energy and wood fuel all got people’s attention. In northern Europe, the United States, Japan and Southeast Asia, many companies got through the crisis relying on wood fuel. However, after the oil crisis, when the oil prices tend to be stable, many companies and factories engaged in wood fuel business closed down. Not only wood fuel, the development of many other kinds of new energy was also affected. Wood fuel energy survives in Northern Europe, because of rich local wood resources and the influence of national policy.

Wood Pellets

In the year 2005, when the oil price rising up again, Arab leader got worried and said: the oil price rising will finally end in impasse of oil country. Why is that? If oil price keeps rising, people will have to seek for alternative energy sources, even if the technology is not mature. Why new energy sources are so popular in recent years? It is because oil prices and the shortage of oil resources.

Referring to the technical research and development, I think that for a company, success means more than technology. Management is also very important. Not all the failure of business is because of outdated technology. So it is with biomass energy. The United States may have the most advanced technology, but it is in Sweden where biomass energy gets the best development, not the United States.

What do you mean about 10km raw material collecting referring to site selection of pellet factory?

• Q: What do you mean about 10km raw materials collecting? And could you please talk about the transportation cost of wood pellets and the site selection of pellet production factory?

Wood Pellet Making Factory

A: 10km refers to raw material transport distance. 10km raw material collecting means you are suggested to collect raw materials within the area of 10km. Within this distance, the freight charges might be affordable. If your materials for pelletizing are too far, the share of freight charges will be enlarged. And it is not cost-effective to collect the raw materials. The “10km” is calculated assuming that the transportation is by car or tractor.

Final Wood Pellets

As for the transportation of final wood pellets, there is nothing to worry about. It is very safe and easy as coal transport. All you have to pay attention is to protect the pellets from moisture. Comparing with call, the transportation cost is slightly higher. But it is much cheaper than oil transportation and it is much safer.

In conclusion, the principle of site selection is nearby raw material, sufficient power supply and easy transportation.

What's the Optimal Length To Diameter Ratio Of Wood Pellets?

Q: I have three questions:

• I have seen a few ring die pellet mill and the diameter of the ring die is all 30-50mm. I saw an article said that the length to diameter ratio of wood pellets should be 9-18. Is this true?
• What can the length to diameter ratio be at maximum for making wood pellets?
• What can the length to diameter ratio of wood pellets be at minimum?

Wood Pellets

A: I don’t know from where you saw the article, but there is no such thing. The length-diameter ratio of wood pellets cannot be so big. It might be suitable for fish or shrimp feed pellets. Actually, the ratio should be decided depending on the raw material. Different raw materials have different optimal length-diameter ratio. But whatever the material is, it can’t be more than 1:7. Otherwise, the ring die will have a seizure.

Why to make straw into straw pellets?

• Q: Hello, I am a student of thermal energy and power engineering. I am very interested in biomass generation power project, especially agricultural wastes such as straw. I asked my teacher that why to make straw into pellets. My teacher told me:”The problem of straw power generation is that the energy flux density of straw is too low. Larger combustion space is needed when burning the straw. Besides, it is inconvenient to transport and store. By making them into pellets, the above problems can be solved“. But I wander, plus the processing cost, it is cost-effective to do this? I have worked as an intern in a power plant. It uses pulverized coal as the fuel since pulverized materials can increase the reaction area. Straw can also be burn directly. So I wonder why make straw pellets rather than grind the straw into small particles and burn them directly?

Straw, Straw Powder and Straw Pellets
straw pellet production line

A: This is a good question and many people have same doubt as you do. Why pelletizing?

Straw is quite different from pulverized coal in ingredients. Firstly, they have the very different proportion. Moreover, their burn time is different. The burn time of straw is very short and can be described as deflagration. Therefore, if use the pulverized coal burning stove to burn straw powder, a lot of reforming is needed in stove design. However, by pelletizing, the traditional stoves can still be used and only a small amount of modification is needed. Although the pelletizing process takes time and money, it is still a cost-effective way to make the most of straw materials. Hope you are satisfied with this answer.

What’s the best size of biomass fuel pellet?

• Q: What’s the best size of biomass fuel pellet? How to choose the hole diameter of ring die? Why the diameter of the pellet fuel on the market is most 6~8mm? Small pellets may be more suitable for small stove or furnace. But is used in large or industrial boiler, isn’t it better to make the pellets a bit bigger, such as 8~12 mm? Dose larger pellet size means lower energy consumption?

A: The diameter of pellets cannot be determined as you like. It is explicitly stipulated in the international Swedish Pellets Standard that the diameter of biomass pellets can be 6mm and 8mm. You can make other size of pellets I you want. And most ring die pellet machines on the market are capable to make pellets with several different diameters. But if you make pellets for selling, especially for export, it is important to know the stipulation about pellet diameter in the place of sale. Pellets not conform to the standard can’t be hot sale anyway. Everything happens for a reason. So if you want your pellets sell like hot cakes, don’t run counter to the international standard! However, if you just want to make small scale fuel pellets at home to your own for heating or cooking, you can make any size of pellets as you like and as it is convenient for you to use.

What’s the calorific value of biomass pellet fuel?

• Q: Hard coal or white coal is the common used fuel our local. Its calorific value is no more than 3600 kcal. I want to know the calorific value of biomass pellets.

Coal Vs Biomass Pellets
Buide Wood Pellet Line

A: The calorific value of hard coal is lower than corn straw pellets, let alone high quality wood pellets. The calorific value of corn straw pellets (moisture ≤5%) is about 3700 kcal/kg. For wood pellets, the value is can be more than 4300 kcal/kg. The combustion of coal is incomplete. Generally, there is still  200 ~ 300 kcal/kg left in the coal cinder after burning. However, for biomass pellets fuel, the heat value can be released in full. With integrated computation, the heat value of coal is much lower than biomass pellets. But during biomass pelletizing, it is very important to pay special attention to the moisture content. Keep the moisture content of the final pellets less than 8%, otherwise, the calorific value will be discounted.