Bulk Solid Heat Exchangers - Vertical
Plate type Bulk Solids Cooler/Heater in general
The plate type Bulk Solids Cooler is conceptually a very simple piece of equipment. It consists of an inlet hopper, one or more plate banks in parallel and a mass flow device. The product enters in the top, forms a cone above the plates and flows between the equal flow channels in gravity flow. The cooler operates with the product level always maintained above the plate banks. So it operates always full of product. The mass flow device creates equal movement of bulk solids over the whole cross-section of the cooler. Cooling water flows through the plates. A relatively simple level control at the top (not in our scope) generates a 4- 20 mAmp signal to control the mass flow device at the bottom in such a way that what comes in at the top leaves at the bottom within maximum and minimum inlet hopper level set points.
The Plate type bulk solid equipment is used in bulk solid handeling:
- Bulk solid cooling
- Bulk solid heating
- Bulk solid drying
More general spoken cooling and heating of Chemicals, Fertilizers, Polymers, Minerals, Sands and drying and heating of Bulk Oil seed.
Typical applications are bulk solid prills or granulates of:
- Ammonium Nitrate
- Ammonium Sulfate
- Potassium Chloride (KCl)
- Kalium Nitrate (KNO3)
- Rape Seed
- PE or HDPE
Mosman compared to other bulk solids coolers/heaters
Eliminate Horizontal Surfaces
From an engineering point of view it is important to design the cooler with as few as possible internal horizontal surfaces where product can stay behind. From this type of equipment bridging should also be prevented. As a result equal plate spacing is very important. The construction with flexible hoses that others use are introducing problems with varying plate spacing i.e. not constant flow channels.
As a result many plate spacers are required and these can be the cause for product particles to stay behind. The horizontal pipe connection that others use are creating 2 large horizontal surfaces (at water inlet and water outlet) at one side of the cooler. Due to the construction with flexible hoses others require large supports below the plates to hold the plates on their location. Obviously these supports are area’s where product can and will stay behind.
The welded execution of the Mosman slot manifold design guarantees this equal plate spacing, eliminates horizontal pipe connections on each plate and reduces the number of required plate spacers to the minimum.
Eliminate and Prevent Moisture
Moisture is the number 1cause for caking. There are basically 2 types of moisture. The first is internal moisture, coming out of the product and moisture that enters the unit together with the product at the top. The second type of moisture is coming from outside into the cooler after the product is already inside the cooler.
The first type of moisture is a problem, typically for every vertical heat exchanger and should be handled by choosing the correct cooling water temperature. I.e. a water temperature above the dew point of the air surrounding the product. Engineering according this principle, condensation of this type of moisture at the cold surface of the plates can be prevented. Luckily, the dew point decreases from top to bottom. In most cases it is possible to maintain a workable ΔT between the product and the cooling water. It is however also possible and in many cases we recommend to inject a relative small amount of dry air in the cooler at the top of each plate bank. We engineer the amount of air, not to interfere with the product flow.
The second type of moisture can only be eliminated 100% by using the Mosman bulk solids cooler. It is clear that every opening in the casing that introduces air from outside the cooler, can and will be the cause for unwanted moisture entering the unit. Obviously this should be prevented. Competition still offers the staggered pipes construction whereby the water connections go through holes in the casing and then via flexible hose connections to the water manifold that is installed outside the cooler. The openings are oversized for thermal expansion reasons and these oversized holes should be sealed off. From an engineering point of view this is not a preferred solution. Proper engineering should prevent to generate problems.
The welded Mosman slot manifold design has completely eliminated all openings in the casing. So there is no fear for this kind of moisture problem.
Most important advantages of the Mosman Slot Manifold Vertical Heat Exchangers
- No caking inside the installation
- Efficient temperature distribution
- Minimum of service costs
- No delicate parts