Single Phase Pellet Mills, what are the Problems when making Wood Pellets?

When it comes to making wood pellets, your choice of pellet mill is limited by your available source of power. For domestic properties and some commercial buildings, a single phase connection is used which has a voltage between 110v – 240v. For many commercial buildings, a three-phase connection is available which can carry a higher voltage of between 230v – 400v. When it comes to using a single phase pellet mill various limitations have to be acknowledged. These include the maximum power the pellet mill can consume.

The Power restrictions of Single Phase

Single Phase Pellet Mill
A single phase mini pellet mill

If you only have access to a single phase electrical supply you are limited by the maximum power draw the pellet mill can demand. On a standard domestic two/three pin plug the maximum motor draw without tripping will be around 2.2kW. If there is a dedicated connection (similar to that used for a cooker), potentially the motor size could be increased to around 7kW.

However, if you are intending to make wood pellets this is not a lot of power to play with. Quality wood pellet production requires high compression, which in turn demands a high power input from the pellet mill. Without sufficient power, a single phase pellet mill can run into problems.

Potentially Increased Pellet Mill Die Blockages

Blocked pellet mill die
A blocked die on a single phase pellet mill can easily happen.

The number of Amps (power) a pellet mill draws depends on the type of material being processed. For instance, a single phase pellet mill can quite happily process an oily animal feed mix into low-density pellets. However, when it comes to processing wood pellets there are more intensive power demands. As wood has a higher material density and the pellets are also produced to a higher density this can lead to complications. As the single-phase pellet mill starts to process wood pellets the amps will increase. If there is a change with the raw material feed rate or the moisture content changes this could lead to issues.

As the pellet mill starts to work harder to push the wood through the die the motor amps rise. With a single phase pellet mill, it’s very easy to reach the limit of around 6 amps. After this point, the electrical connection will trip out. If this happens with the material left in the die it will start to cool down and harden. Depending on the condition of the die this could lead to a pellet mill die blockage.

Productivity per Hour Restrictions

As a roughly general rule when it comes to making wood pellets it requires 1kW of pellet mill power to produce 10kg/h of productivity. Therefore, on a single phase connection and motor power of 2.2kW, the productivity per hour will be 22kg/h. This is where you really have to weigh up the value of your time to the volume of wood pellets produced.

Wood Pellets
It takes 1kW of power to produce 10kg/h of wood pellets

A pellet mill is not a ‘set and forget’ operation. You need to be actively engaged, monitoring the raw material and pellet press at the same time. Therefore, what you really need to consider is if 22kgs of wood pellets are worth an hour of your time. There is also the matter of pellet mill maintenance to factor in. Furthermore, it’s not really an hour of your time, it’s even more. You also have to factor in the time taken to prepare the raw material ready for the pellet mill. That means reducing it to a suitable particle size and moisture content.

You can only run One Piece of Equipment at a Time

Single Phase Hammer Mill
Single phase hammer mill

As previously stated, a single phase connection means all available power is used by the pellet mill. Therefore, there is no surplus power available to run a hammer mill for particle size reduction. If there was suitably available power you could be using the hammer mill while the pellet mill does its job. As with single phase, there isn’t sufficient power, you have to use one piece of equipment at a time. This therefore obviously increases the total time it takes to produce a fairly small quantity of wood pellets.

There are small hammer mills on the market that use small diesel engines. This would obviously mean you could be using both the pellet mill and hammer mill at the same time. It should be noted that small Chinese diesel engines are not very efficient. Therefore the cost to process the material could be much higher than you would expect.

Is there a use for a Single Phase Pellet Mill?

From reading the above it should be clear that a single phase pellet mill is not a viable pellet production setup for volume. The cost per ton when you factor in the labour/time is not viable. However, there is still a viable use for single phase pellet mills.

Research and testing before investment in a pellet plant is probably the number one use for single phase pellet mills. Before a significant investment is made in a pellet plant a pilot project can be set up to produce small volumes of pellets. This can be a ‘proof of concept’ to help to secure funding. It can also be a useful setup to train future pellet plant operators.

The other exception of use for a single phase pellet mill is for producing BBQ wood pellets. As the profit margins are so high for BBQ wood pellets it can be viable to produce them on a single phase pellet mill.

Final thoughts on Single Phase Pellet Mills

Many people start off looking into purchasing a pellet mill to make wood pellets from home. However, before such a decision is made it’s very important to learn as much about the process as possible. Making good quality wood pellets is a challenge, and even more so using a low powered single phase pellet mill. To make the process easier to deal with its recommend to consider a low inclusion pellet binder. This will aid the process and partly address the issue of power limitations with a single phase pellet mill.

Before you purchase a single phase pellet mill it is a good idea to have a chat with a local electrician who will advise on the best way proceed. A dedicated connection for the pellet mill will probably be their recommendation.

I hope you found the above useful. Remember, before you make any purchase make sure you have researched the process of making pellets thoroughly. With this website, I’m trying to produce as many helpful hints and tips from my experience over the years.

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