Batch Dryers

Batch dryers are small portable dryers and they have a central plenum with a column of grain encircling the plenum. They can be manually or automatically laden and unloaded. Among these some are powered from a tractor PTO that allows them to be employed about anywhere. But the drawback is they need more supervision and labor per bushel than other types of dryers. A well operated batch dryer has almost the same energy efficiency as a continuous cross flow dryer with the cooling section heat recovery.

Maximum energy efficiency

The hydraulically driven discharge system drops the whole batch down to the subsequent deck after a pre-set period of time and only after that subsequent deck has first dropped its batch in way no cross contamination can happen. In a batch dryer all the product batch is treated separately with drying zones per drying deck. The amount of evaporation can be set per deck via variation of drying air volume and temperature. Dryer exhaust air is re-circulated back into the heater for maximum energy efficiency and only a limited volume of air is exhausted at a high corresponding humidity.

Consumer of energy largely

Batch dryers are the biggest consumer of energy in most processes. Using the fresh counter-flow technology to replace an existing horizontal dryer you can save up to 50% on energy costs. Compared to the traditional horizontal layers with re-circulation, the dryers save 15-25% on energy costs.

In order to get all product dried as close as possible to the acceptable maximum you need a dryer with a high moisture uniformity. Modern counter-flow dryers can be configured for drying to standard deviation as low as 0.25%. Even a dryer with perfect air flow design does not offer with proper results unless it is capable of reacting automatically to changes in circumstances such as temperature and humidity of the air product flow rate and moisture of wet product.

Recent technology

Plenty of research put in the field has contributed to the development of the technology particularly batch dryers. Extensive list of design optimizations and control system procedures aimed at minimizing the risks of fire, explosions or other dangers for operators are largely considered. With some companies making such instruments are highly competitive like a network of sensors and signals enabling the PLC to trigger alarms if necessary, which eventually escalate to the shutdown of burners/ heaters or the entire dryer. Thus with advent modern technology in chemical engineering batch drier finds a particular significance.

Questions:

• What is a batch dryer?
• What are the recent technologies of batch dryers?