The case
A medium-sized Italian company cultivates approximately 200Ha of land for white maize production, reaching 3,000 tonnes of grain harvested and processed in a single season. In 2009, the customer in question purchased a Mecmar dryer – model S 35/280 T2 – integrated with a direct fire heating system and diesel burner. Upon arrival at the company, the dryer was immediately placed next to the shed for two reasons:
1. to facilitate its operation by tractor
2. to be able to choose whether to unload the dried product inside the warehouse or onto a wagon
Thanks to its direct-fire heating system, the S 35/280 T2 dryer maintains the high quality of the dried maize, but also ensures the possibility of processing various types of grain, while always guaranteeing a high drying speed. Due to its tractor-driven operation, the dryer can be moved easily to any part of the farm, as it does not require a continuous power supply.
The dryer in 2009: what were the most popular features of the plant?
Arrived at the customer company in 2009, the drying plant consisted of:
- Dryer S 35/280 T2
- Machine loading area (from pile)
- Tractor required to operate the dryer
The agricultural dryer has a capacity of 47 m3 and is capable of drying and cooling approximately 12 tonnes of maize in 24 hours, the moisture level thus dropping from 20% to 14%. Although this first installation already allowed the customer to dry medium to high quantities of product, it was soon recognised that the utilisation and efficiency of the plant could be further optimised. How?
First and foremost, by finding an alternative mode of operation to that of the tractor and adopting a fuel other than diesel, not fossil but natural (biomass, in fact). In addition to this, if the dryer had a generator with a heat exchanger, the quality level of the maize would be more highly valued on the market. Finally, it is possible to automate – as well as simplify – the post-drying phase. Let’s see how!
How is the drying plant structured today?
To date, the system installed at the client company is as follows:
- Dryer
- Gearmotor unit
- 1 MW wood chip boiler
- Wood chip loader
- Ash and flue gas separator cyclone
- Conveyor belt
- Elevator
- Storage silo
- Storage silo
Today the customer:
- has a more automated plant: a conveyor and two storage silos have been added to the original plant;
- enjoys a more confined and cleaner working environment: the dried grain is unloaded directly from the handling system, without the need to move tools;
- incurs lower fuel costs due to the use of the biomass boiler;
- achieves higher quality drying compared to direct fire, thanks to the use of a heat exchanger.
With the aim of freeing up the tractor used to power the dryer and thus allocating it to other uses, the customer installed a diesel-powered gear motor unit to operate the PTO.
A biomass heat generator – model BM1000 – developed and built by Mecmar was then installed in the dryer and used to burn wood chips of A1+ quality. The power installed on the burner is quite high (approx. 1 MW), which implies that the boiler volume must also be just as large in order to have a good exchange efficiency.
In particular, the savings in terms of consumption, as well as the possibility of utilising natural materials such as biomass in an intelligent and profitable manner, are immediately appreciated in a system of this type.
However, setting up a biomass plant in-house requires some special attention. Firstly, the installation in question is bulkier than a traditional grain dryer. A biomass drying system also requires a safe and always controlled electrical and fuel supply system. It should also be remembered that such an installation requires the installation of a fume removal system so that the ash from the drying process is not dispersed into the environment.
To prevent the maize still to be dried being contaminated with the products of combustion, it is essential to separate the hot air used in the drying process from the air heated in the furnace. For this reason, the heat generator must be equipped with a heat exchanger with large exchange surfaces, so that the drying air is heated appropriately. In this way, gentle drying of the maize is guaranteed, and only with clean air. The processed grain can then be destined for animal and human consumption, according to high quality standards.
Finally, in order to optimise the post-drying phase, a conveyor belt, an elevator and two storage silos were installed in the customer’s plant, which allow the dried maize to be stored automatically and without the use of manpower.
Published data refer to corn and are calculated with mathematical models that use clean and ripe products and in normal operating conditions with 120°C drying air temperature and one hour cool-down time. Please do not hesitate to contact the nearest Mecmar dealer for more information.
Under our policy of continuous improvement, we reserve the right to change specifications provided without prior notice.
