It is well known that briquetting is one of the best ways of turning wooden waste into ecobiofuel of high quality. Since the wastes have minimal and sometimes even negative worth and briquettes are sold at a price of at least 100 Euro per ton it is logical to conclude that producing briquettes can bring high profit. Is it really true?
All factory costs can be divided into direct (raw materials, energy costs etc.) and indirect ones (land use tax, office salary etc.). Direct costs usually are proportional to the production but indirect costs occur even in case of demurrage. This brings us to a conclusion that profitable production shall have minimal demurrages and the coefficient of equipment use shall be close to 100% (to make the calculations easier we don’t take into consideration any other factors).
Which equipment meets these requirements? Today there are three most common briquetting presses: screw press (extruder), hydraulic press and mechanical press. Let’s discuss them in details.
1. Screw press (the most well-known is «Pini-Kay»). The briquettes produced on such press in section look like an oblique octangle with a hole in the centre. They have the highest density (more than 1,2 kg per dm3), the longest burning period, the don’t change their characteristics in case of prolonged storage. In other words they have the best consumer attributes, and it is not surprising that they have the highest price (up to 7000 RUR per ton wholesale and up to 12000 RUR per ton in retail). But the highest price for this type of briquettes is brought about not only by its high quality but mostly by very low scale of production (and, hence, by high self-cost). Because of specific technical characteristics the coefficient of screw presses use is rarely higher than 50%. This means that in case of 400 kg per hour productivity within a month you will get not 288 tons of bricks (24х30х0,4=288), but only 50…100 tons. As a result, one of the cheapest presses (the price without a bin is around 1 mln. RUR) has the longest payback period.
2. Hydraulic press (the most well-known is «RUF»). The briquettes produced on such press look like common briquettes or sometimes like cylinders. They have the lowest density (up to 1 kg per dm3), the shortest period of burning, can’t be stored for a long time if not in vacuum pack and are frequently destroyed when being transported. In other words they have the worst consumer attributes and usually the lowest price. The press unit capacity is usually is not higher than 500 kg per hour. The production process on the hydraulic press is the easiest from the point of view of personnel qualification. The equipment utilization rate is maximum 90%. The hydraulic press is much more expensive than the screw one and despite this it still has the shortest payback period.
3. Mechanical press (the most well-known is «C.F.Nielsen»). The bricks produced on such press have an average density of 1…1,2 kg per dm3, prolonged burning period, do not change their characteristics in case of prolonged storage. Such briquettes are cheaper than those produced on a screw press but more expensive than ones after hydraulic press. An important advantage of such presses is possibility to produce briquettes of various forms (round, square, octangle in section and also with a hole in the centre), which together with a high unit capacity (up to 1,8 tons per hour) provides for a possibility to produce briquettes not only for individual consumers but also for production needs. The process of commissioning for this press is more complicated than for hydraulic one but the process of service and maintenance is much simpler up to the situation when you don’t need any personnel along the working press and the press can be started and stopped automatically depending on the fact that whether there is raw materials in the bin or not. The press can be operating for 1500 hours without any stop (that is 2700 tons of bricks). The equipment utilization rate is more than 90%. It is not surprising that this press is the most expensive and just because of this its payback period for cylindrical briquettes production is 7 months longer than that of hydraulic press. However after these seven months the press will give profit by 10…20% more. For the production of octangle (“consumer”) briquettes the payback period can be the shortest of all the discussed variants.
Conclusion
Every type has its advantages and disadvantages. It is quite a challenge to compare them. But there is one universal criterion – real economic efficiency for a prolonged period of time. This criterion finds its best implementation in the mechanical press and other reasons even don’t need to be named…
As is known, the production of pellets and briquettes from wooden waste as well as from other types of biomass needs the raw material to be chipped first and then dried up 10…12% of moisture content. To do this different equipment can be used. In the XX century one of the most well-known complexes with this aim were drying drums and hammer chippers. But in the XXI century it became necessary to reach one more economic purpose – energy efficiency.
The production of pellets, briquettes, wood-polymer composites and porous ceramic bricks needs the raw materials to be dried and chipped first. Most of the drying equipments require an exterior heating source. In this article we will try to find out which heating equipment is better to be used in the named production process.
