Due to ongoing investments and the resulting increase in cutting, more raw material is now available for pellet production at the Heinrich Holtmeyer sawmill. For this reason, managing director Stefan Holtmeyer decided to purchase a new pellet press. “Since we had already reserved space for a second press when planning the mill, the expansion was relatively easy. Also, we can easily sell the pellets through trading companies within a radius of around 100 km,” Holtmeyer explains during the Holzkurier’s visit to Ottersberg.
Based on the very good previous collaboration and several technical advantages over other products, Holtmeyer decided to purchase a PM7 pellet press from Rudnick & Enners of Alpenrod. As mentioned in the introduction, the plant experts from the Westerwald were already responsible for the planning, project handling and delivery of the pellet mill in 2017/2018.
Several requirements for the new pellet press
The Holtmeyer sawmill processes different types of softwood, which is why the new pellet press has to be able to handle spruce, pine, Douglas fir and larch – and varying mixtures of these types of wood. “We wanted to increase the performance of our pellet mill and reduce the workload of our plant operators at the same time. Therefore, the pellet press had to be able to adapt to varying input mixtures without much effort and produce high-quality pellets. Also, we wanted to reduce maintenance costs and the per-tonne electricity consumption,” Benjamin Rohmeyer, pellets operations manager at Holtmeyer, tells us. The high quality of the pellets is also reflected in the complaint rate, which is practically zero. “We probably produce the best pellets in our region. The trading companies, too, praise our high quality,” Rohmeyer says with a smile. The sawmill by-products are transported directly to the pellet mill on a Rudnick & Enners tubular belt conveyor. First, the sawdust passes through two wet chip containers and a wet chip hammer mill, which grinds the material to a size that can be pelletized. Next, the sawdust falls onto the two belt dryers and then enters the mixing container which also has a device for dosing the starch that is added.
In addition, Rudnick & Enners supplied an infeed station for external material which allows Holtmeyer to integrate purchased by-products into the material flow. Once they have left the press, the pellets are cooled, screened and then stored. The truck loading station was also built by Rudnick & Enners.
New 7-t/h pellet press with technical innovations
Managing director Sven Rudnick puts the output of the PM7 pellet press at 7 to 8 tonnes per hour for softwood, depending on the motorization. In addition to its performance, the pellet press impresses with the automatic roller adjustment and integrated pellet density control. “The pellet press has a wide working and control range. This reduces the need for manual intervention by the operator. We will soon deliver more pellet presses of this size,” Rudnick tells us.
Once they have left the pellet press, the pellets go directly into the Rudnick & Enners horizontal cooler. “We want to cool the pellets gently, without causing further mechanical abrasion. “Also, we don’t want to ‘overdry’ the pellets,” Rudnick adds.
Easier maintenance of the press
“Since November, we have been using only the new press. The work processes are more relaxed for our operators because we don’t have to react immediately whenever there are fluctuations in the input material, for example. Before, we used a number of different dies with different press channel lengths – depending on how big the proportion of pine was, for example. With the new press, we no longer need to do that. The handling has become much easier,” Holtmeyer explains. Changing wear and tear parts also works satisfactorily. “We can change dies in just over an hour,” Florian Janzon says, who is responsible for pellet production.
Another advantage of the PM7 is the automatic roller adjustment. “Thanks to this feature, our employees have less work to do on the rollers, and they are also easier to access for maintenance work,” Rohmeyer comments. The highly user-friendly automatic shutdown and startup processes are also worth highlighting. Holtmeyer is particularly satisfied with the solid build: “The press is extremely low-vibration.” The total weight is around 18 t. Safety is another crucial aspect for Holtmeyer. “During the shutdown process or in the event of a system malfunction, the rollers automatically move to a waiting position, i.e. away from the die. This also gives the operators more time to react – and it reduces the pressure on the employees to react,” Rohmeyer says.
Two years ago, Rudnick & Enners also delivered a second belt dryer including a heat recovery system.
When the pellet mill was put into operation in 2018, the annual capacity was just under 30,000 tonnes. “Initially, we only wanted to operate the mill in two shifts, but we quickly switched to 24/7 production. With the new press, we are now able to produce around 55,000 tonnes a year,” Holtmeyer tells us. This quantity does not include the old pellet press, which is still there as a backup. A large part of the produced pellets goes to the trade sector. Nearly 10% are needed for Holtmeyer’s own combined heat and power plant. “We are confident about pellet sales. We set ourselves apart with the high quality of our pellets, which are also a good alternative to imports,” Holtmeyer is convinced and adds in conclusion: “Our requirements for the new pellet press were met. We are more than satisfied with it and with the new horizontal cooler.”
