BATCH VS CONTIUAL MIXED FLOW
As technology improves, advances in Agri-processing equipment allows farmers a wider variety of options when choosing Grain drying equipment. The improved technology available today can put farmers firmly in control of their drying costs and quality control and the affordability of this equipment as well as the cost saving it provides makes it extremely viable financially
BATCH GRAIN DRYING
Batch drying is a system by which a Volume of grain is loaded into a Batch Dryer, the volume is fixed by the holding capacity of the dryer, it is then dried to the required moisture content level. The dried grain is unloaded from the dryer, and a new batch of wet grain can be loaded in and the drying cycle can continue. Batch drying, therefore, requires loading and unloading time for each batch of grain needed to be dried. Batch Grain dryers have many configurations, including thin layer bed, thick layer bed, vertical column and round radial dryers. Batch grain dryers have the disadvantage of over-drying the grain nearest to the wall of the incoming hot air. Grain nearest to the wall of the incoming hot air loses its moisture first to the hot air, Whilst the grain lying further away takes longer to dry. This results in large variances in moisture content across a batch and can impact greatly on quality. The difference in grain moisture level between the layer nearest to the hot air and the outer layer varies with column thickness, temperature of hot air, and airflow rate. There are Batch dryers available with stirring or mixing options , these are usually mechanical in nature and cause damage to the grain as a result.
CONTINUOUS MIXED FLOW GRAIN DRYING
Continuous mixed flow grain dryers are Column grain Dryers that operate in a continual process. Initially the dryer is loaded with wet grain and the drying process begins. The grain passes through the dryer, mixing the grain as it passes through the heating elements, air flow is in both counter and concurrent directions, this combined with the non-mechanical mixing effect of the grain passing through the dryer ensures even drying. Grain is tested during the drying process and if further drying is required, the grain is recycled through the machine. Once grain has reached the desired moisture level it is discharged and wet grain is immediately loaded in at the same time, ensuring a continual process. These dryers often have multiple heat zones and can use higher air temperatures without crop damage than batch dryers as all grain kernels are exposed to the same air temperatures. The dryers also incorporate a cooling phase in the drying column. The dryers are usually self cleaning and are energy efficient, using about 40% less energy than a conventional batch dryer without heat recovery. The high degree of automation of these machines means a huge cost saving in terms of labour. One major advantage when compared to a batch dryer with a screen column is the ability to use the dryer for a wide variety of different grains; from small rape seed to wheat, maize or soybeans. The continuous mixed flow drying system offers lower operating costs compared to batch drying systems as well as uniform grain moisture content after drying ensuring better quality outcomes.