Few industries rely on a consistent climate as much as the agriculture industry does. Whether it is keeping livestock warm or cool, providing cold water for equine pools, heating greenhouses or drying out crops, meeting and maintaining precise conditions are key to maximising your processes.
Correct storage is a vital part of the process to ensure the customer receives your perfect product. Incorrect storage conditions can be your worst enemy. It can result in wastage and reduced quality - all of which can contribute to increased environmental costs.
For farmers, the winter period often demands an immediate response to adverse weather - especially if crops become vulnerable to wet conditions. During spells of heavy rainfall, it is important to maintain productivity levels, as well as the effect the climate can have on both storage facilities and harvesting.
Moisture problems usually occur in storage facilities and other similar buildings, where goods kept inside may be liable to damage. You can protect the contents using dehumidifiers and similar drying equipment, which enable humidity levels to be controlled and maintained. Carefully managed storage areas represent a safe and efficient way of holding large quantities of produce while keeping energy costs low.
Storing dry bulk materials in places like a bulk silo is a challenge because the empty space right above the stored product – known as the 'ullage space' – often suffers from condensation issues. Many of the substances that are stored in bulk silos are hygroscopic, which means they are prone to absorb moisture.
Examples of hygroscopic materials include, ammonium sulphate, baking powder, calcium phosphate, caustic soda, cocoa, coffee concrete, corn sugar, dextrose, salt, flour, gelatine, gypsum, lime, plastic pellet resin, potassium chloride, starch and urea.
Excessive moisture from the air inside the silo spurs bacterial growth, potentially spoiling the stored product. Absorbing moisture can also cause hygroscopic products to bridge across the silo, adhere to the sides of the silo, block the silo, spoil the product and affect aeration of the product at the bottom of the silo preventing the product leaving the silo.
To minimise the effects of product build-up, mechanical devices like hammers and vibration pads will often be fitted to bulk handling equipment before delivery. This approach does not solve the core problem of moisture and, as a result, the powders still lump together.
Dehumidifiers can help regulate the moisture content of the stored commodity to levels that prevent condensation and mould growth. If condensation issues are not taken seriously, it may result in loss of product quality, hampered production, blocked pipes, increased maintenance requirements that ultimately lead to lower productivity and higher production costs.
Aeration is commonly used to cool the stored products in a silo to reduce moisture migration and condensation potential near the top of the stored products, but this type of process is highly dependent on prevailing exterior climatic conditions. During rainy seasons and in humid tropical areas, aeration is very difficult. By using a desiccant dehumidifier that incorporates cooling coils, you will be able to control the relative humidity within the silo, as well as the product moisture content and temperature. This ensures that the quality of your product can be maintained for longer storage periods irrespective of the prevailing weather conditions.
The solution is to simply condition the space above the product known as the ullage space with dry air. Keeping the air in this area at a lower dew point than the coldest surface will eliminate condensation.
This is done with a desiccant dehumidifier. It can be installed in a small enclosure next to the lorry loading pipe and then connected via a coupling that can easily be disconnected when loading into the silo.
Once installed, dry air is delivered using the silo lorry loading pipe or a dedicated dry air pipe. This pipe runs up the outside of a silo. A lorry will connect to the pipe to discharge product into the silo. When not in use for loading, this pipe can be utilised to deliver dry air into the silo.
If permanently connected a diverting valve or shut off valve will be needed to isolate the dehumidifier when lorry loading is taking place. During operation, dry air is delivered into the silo on a total loss basis. The air is discharged from the silo either from the silo vent or via the dust plant.