Introduction
According to Matt Davies Stockton, the thermal processing of bulk solids and bulk powders is a necessary step in many industrial processes since the materials often need to be heated for degassing, crystallization, and more. It is used in many heavy manufacturing industries such as pharmaceuticals, food and beverage, chemicals, and for processing metals and materials as well.
How to bulk solids cooling work
Bulk solid coolers are designed to cool a variety of free-flowing bulk solids such as plastics, fertilizer, minerals, chemicals, dried biosolids, and other types of solids such as powders, crystals, and granular. The mechanism essentially works due to the gravity flow of the products that move through a bank of welded heat exchanger plates that are cooled with water.
Indirect heat transfer technology is currently at the forefront of bulk solids heating, cooling, and drying since it efficiently removes the risk of contamination and reduces the need for dust collectors and ventilation.
The product that needs to be cooled is allowed to move between the plates and is cooled by the cooling water that flows through the plates in a counter flow via conduction. Indirect heat transfer is possible since the two streams are separated. A discharge feeder is mounted below the plate bank which helps to facilitate the mass flow of the product.
The design of a bulk solids cooler is more compact and energy efficient in design compared to fluid bed or rotary drum coolers. And it virtually produces no dust emissions. Thus, it is the preferred choice of cooler in fertilizer plants and many other industries.
Now, let’s see the critical requirements of a bulk solids heat exchanger:
- Counter flow design – To maximize thermal efficiency, a true counter flow design is needed on the water side that is parallel to the dew point curve.
- Purge air system – The purge air system is designed to improve thermal efficiency by lowering the dew point in the product cooler. This helps the system to utilize lower water temperatures.
- Water temperature profile – The water temperature profile is an important consideration since the temperature of the plates should always be above the dew point of the air while the product flows through the exchanger.
- Comprehensive instrumentation – The water loop, purge air, and product require comprehensive instrumentation since it offers vital information that helps to optimize the performance of the system even under varying operating conditions.
- Insulation – If condensation occurs inside the wall of the cooler, it can lead to caking inside the walls of the exchanger and ultimately lead to corrosion. Properly insulating the inside walls can help to keep them above the dew point which will prevent condensation.
Conclusion
Matt Davies Stockton suggests you thoroughly understand how bulk-solid coolers work if you are considering investing in the technology for your business. Although bulk solid coolers offer many advantages over traditional coolers, the stainless-steel exchanger plates are subject to corrosion over time. Thus, it is important to take care of the maintenance requirements if you want them to function as efficiently as possible.
