Countless small-scale heating systems worldwide are equipped with pellet furnaces. More and more medium- and large-scale heating systems for industrial plants, or bio power stations, are also entering the market.
For one of the largest pellet storage plants in England, Agromatic was contracted to supply temperature monitoring systems for the wood pellet storage silos. So far, eight concrete bins with a cylindrical height of about 57m and a diameter of 37.5m have been erected, and further extensions over the next five years are in planning.
The storage capacity of all bins is approximately 4.4 million square metres, which is equal to 5mt (million tonnes) of material. Each bin is equipped with Agromatic’s most rugged monitoring cables, and the latest temperature monitoring technology to meet all relevant safety requirements.
In 2008 Agromatic started engineering a new generation of temperature monitoring cables, equipped with special software and designed to meet all requirements particular to the pellet storage industry. Since then, all the systems have been tested and proven effective, and are used in the following applications:
- wood pellet silos (pellet size 5/6mm diameter, for private
- industrial pellet size 30/40mm and 50mm diameter; and
v wood chips and wood chunks.
- Wood pellets make high demands on the robustness of the
- rough and edged material with high abrasiveness;
- high product humidity (chunky wood); and
- large bridging tendency when empting bins, which results in high loads.
The silos are enormous, and can take extremely large loads.
TEMPERATURE MONITORING IN WOOD PELLET SILO
Risks during storage may occur due to self ignition of imported
smoldering particles, possibly caused by wear of machinery
(friction, abrasion). Low fumigation of pellets after production
also carries large risk potential.
It is nearly impossible to detect and extinguish all possible
It is therefore essential to have effective temperature monitoring of stored pellets, in the interests of safety. Reliable detection of a temperature rise is monitored by special software, which detects the smallest temperature changes in order to prevent possible danger, or initialize safety provisions.
TEMPERATURE MONITORING CABLES AND ITS SENSORS
Specially designed monitoring cables are different in essential points from cables that have successfully used in the grain industry for many years:
- higher tensile strength; higher admissible forming pressure; and
- higher mechanical strength by reducing abrasion and frictional wear.
SUSPENSION BOX BD90
This particular suspension box offers the possibility of reinforcement into the bin ceiling, when cables are subsequently installed. Integration into the bin ceiling is possible using an additional flange for basic fixing.
For both alternatives, monitoring cables can easily be installed into the silo on the bin ceiling.
It is therefore no longer necessary for anyone to enter the bin silo. The suspension boxes are approved and ensure separation of Ex-zones. Usage is possible within the building or on the silo roof. Protection class corresponds to IP67.
MONITORING CABLE GKDH/BD90
Basically, the temperature monitoring cable is supplied with an integrated two-wire sensor technology. The system guarantees that the high standard demands of the application are fulfilled and that all safety requirements are met, according to relevant Ex-regulations. The example shows the complete execution of a flush suspension box solution BD90/BD90P.
If it is not possible to allocate the connection cables into an existing site, Agromatic offers a wireless data communication system. The wireless transmitter can be mounted on the measuring cable suspension head at any required location (inside or outside buildings).
Depending on the commodity and its volume, the number of measuring points and sensors are defined accordingly. Best possible scanning is achieved in a radius of 3.5m, and sensors are best placed each 3.5m in height. When storing chunky wood or fresh and humid material, it is important not to exceed a distance of 3m.
The measured values of the digital sensors, each of which has its own address, can be read wirelessly or by bus. At the same time, values are transmitted directly to the monitoring unit.
A powerful industrial computer provides
the basis for
stored and related
product values are
Ideally, and for security reasons, it’s strategically best to use the Agromatic software and control unit primarily. From there an integrated safety programme
allows for a fast automatic and manual access to critical bins.
The registration of primary safety data should never be
processed through third data stream for data evaluation in order
to completely exclude the possibility of communication errors.