Controlling a pelletizing line with minimum operator intervention is essential for consistent production quality

Does your operator need to stand in front of the pelletizing line to ensure maximum output and consistent production quality? Maintaining the quality of pelletized animal feed is an area where experience and know-how of the plant manager and operator play key roles. Ensuring the maximum productivity and consistent production quality are prime considerations for animal feed producers, so PROMASST process control software from KSE Process Technology have developed a control solution that optimizes the process with minimum attention from the operator.

Why produce pellets?
Although pellets have many advantages compared to mash, pelletizing adds an extra step and costs to your process. There are many physical benefits from a process pointed view, such as reduced waste (dust and fines), ease of handling and increased bulk density. From a nutritional point of view, pellets can also improve palatability and give a better feed conversion rate. Because of heat treatment one could also reduce salmonella, etc.

In production, the objective is to provide consistent pellet quality under different conditions and varying ingredients in the formulas. Pellet quality can be defined in terms of durability and hardness, and the amount of fines in the product, so production without generating excessive fines is also important. However, the pelleting process is far from a ‘standard’ process. The influence on the quality of the end product includes temperature. You also need to consider type of animal feed (chicken, dairy feed, pig feed, etc.), formula or recipe, required pellet hardness and size, type and quality of the raw materials, coarseness of the feed, the desired production capacity in tons per hour, whether heat treatment is required or not and the required quality level of the end product. All in all, a real challenge to control all the variables and get the same results time after time!

The pelleting process
There are many possible variations of the production process, the conventional way of pelleting comprises four basic steps;
1. Conditioning – treatment in which the time, moisture level, temperature are the key parameters;
2. Pelletizing – transforming meal into pellets by pressing it through the die, which requires considerable energy. The key parameters are the die, the die speed, the rolls and the film between the die and the rolls;
3. Cooling – cooling the pellets.

Conditioning
Conditioning is perhaps the most important factor that influences the pellet quality and probably the least understood process by operators, plant managers and equipment suppliers. It covers all the treatment that takes place after mixing and grinding the mash, and before the mash enters the die of the pellet mill. Conditioning is carried out because it improves both the nutritional and the physical quality of the end product, and the efficiency of the process. For example, it increases the pellet durability index (PDI), pasteurizes the mash, reduces anti nutritional factors (ANFs), improves feed conversion ratio (FCR), decreases processing costs, increases production rate and increases gelatinisation of starch. Conditioning is mostly based on steam (a combination of temperature and moisture), and the key parameters are:
– Retention time which must be long enough for the absorption of liquids and steam and to carry out pasteurization, yet short enough to deliver a good pellet quality;
– Moisture content, which is influenced by water or steam and ensures easier passage through the die and agglomeration;
– Temperature controlled, using wet or dry heating, and too high a temperature may harm nutritional value;
– Pressure (shear), which increases gelatinization of starch.

There are very specific time, temperature, moisture and pressure restrictions for the conditioning of different raw materials, and all of these need to be known and taken into consideration in the process control.

Pelletizing
Controlling the pelletizer is another area where feed producer rely heavily on the experience of operators. The people that stand in front of these machines for years gain an understanding of the characteristics and potential pitfalls, and can make small adjustment on the fly. However, this is not a guaranteed repeatable method of production because it involves too much personal know-how. The know-how of the experienced operators needs to be preserved.

Controlling the variables
Because there are so many variables that influence the pelleting process, determining the optimum conditioning method must be evaluated on a case-by-case basis. It is virtually impossible to set a standard on the time, moisture, temperature and pressure parameters for fine tuning conditioning. It also depends on the formulation, hygiene requirement (such as pasteurisation), process control and cost. Finding the balance for all these parameters is a challenge as each formulation has its own settings. Ensuring that the conditions are consistently repeated regardless of who is operating the machine, is another challenge, and one that KSE’s PROMAS ST pelletizing line software can help.

Equipment independent
The PROMAS ST pelletizing line control software is independent of machine brand and type, and is therefore compatible with all regular brands of pellet mills and pre-compacting equipment. It can control pelletizing lines, double pelleting lines, pelletizing lines with expanders, extruders, pre-conditioners and it can control also the processes of ripening, drying, cooling, crumbling, sifting and (vacuum) coating.

Self-learning software
One of the areas where PROMAS ST benefits feed producers is that it significantly reduces the company’s dependence on the experience and know-how of a few key people. It effectively ‘captures’ their experience and ensures that the production quality remains constant. By learning the machines’ optimum settings while running – and not simply using the last known settings – this pelletizing line control software will constantly correct the settings for maximum output within the given parameters. This ‘self-learning’ approach involves monitoring all the equipment all the time, analyzing all process data and acting on it.

One system for total control
The software automatically starts and stops the line and runs on optimal output. It restarts in the event of failure, stores data and events, and automatically rejects or re-processes product if given parameters are not matched. In addition to offering total control and registration, the system also takes care of perfect in-line dosing of steam, liquids and enzymes. It is easy to understand, highly automatic and ensures no loss of information.

PROMAS ST is a complete family of modular software for controlling the entire production process. As a modular system that is independent of hardware manufacturer, the feed mill automation can be easily upgraded without having to re-write the whole control system. And because feed production involves much more than the actual processes like grinding, mixing, pelletizing and cooling – think of logistics, storage, cleaning, automation, quality control and so on – the PROMAS ST software applications cover data handling, reporting and analysis, quality and performance data, process control and service and maintenance. The platform can also be interfaced into ERP systems.

Do you want more info? Click on animal feed processing technology.