Technology
Keep your equipment operational with Klaren International’s self-cleaning heat exchanger technology. Vertical shell and tube heat exchangers operate with a clean surface, due to the application of a fluidized bed of solid particles. Conventional heat exchangers have the problem of severe fouling in the tubes. This can happen in just a matter of hours in severe cases. With the solid particles of our innovative self-cleaning heat exchanger technology, solid particles will be continuously cleaning the walls of the heat exchanger tubes with a mild scouring effect. These solid particles have diameters of 1.5 to 5 millimetres and consist of glass, ceramic or metal. A constant heat transfer coefficient is maintained by cleaning the heat exchanger tubes at an early stage of formation. Moreover, these particles reduce pressure drop compared to conventional heat exchangers and enhance the heat transfer at lower liquid velocities. When the rate of removal of deposits by the particles exceeds the rate of precipitation of deposits, zero-fouling is guaranteed.
How does the self-cleaning heat exchanger technology work?
The cleaning principle of the heat exchanger tubes is an ongoing cycle. It is based on the circulation of solid particles through the tubes of a vertical shell and tube heat exchanger. First, the fouling fluid flows up through the heat exchanger tube bundle and passes through the inlet and outlet channels. These channels are specially designed for this process. Second, the solid particles are fed to the fluid using a distribution system in the inlet channel. This happens to ensure consistent division of particles over all the tubes. The particles are then fluidized by the upward flow of liquid to remove any deposit at the beginning of fouling formation. They create the mild scouring, cleaning effect on the wall of the heat exchanger tubes. Lastly, after the particles are detached and separated from the liquid by the tube bundle, they move to the inlet channel through an external downcomer. After this, the cycle is repeated.
To control the amount of particles fed to the inlet, a part of the inlet flow to the heat exchanger is used to push the particles from the downcomer into the inlet channel. Changing the amount of particles is one of the parameters to influence the cleaning mechanism. Other parameters are particle size and material and the fluid velocity.
With this technology, fouling or clogging of heat exchangers can be prevented or minimized. The fluidized bed effectively handles many types of fouling including scaling, whether hard or soft, originating from biological, crystallization, chemical or particulate fouling mechanism, or a combination of these. A wide variety of fluids can be handled ranging from aqueous solutions to oils and slurries.
Video about the innovative technology
Watch the video presentation about our innovative technology and the process of cleaning the heat exchanger tubes.
Webinar Self-cleaning Heat Exchanger Technology
In this webinar the Self-cleaning Heat Exchanger Technology is explained.
The following topics are addressed:
- Fouling
- Operating principles
- New versus Revamp
- Applications
- References
Webinar Implementation Self-cleaning Technology in Evaporators
The self-cleaning fluidized bed heat exchanger technology has been successfully applied in Multi-Effect Evaporators and will be applied in MVR Evaporators as well. The technology has proven to be able to eliminate (severe) fouling in evaporators and ensures constant evaporation capacity and longer operational time.
In this webinar it is explained how the self-cleaning technology can be implemented in MEE (single effect/multi-effect/TVR) as well as MVR.
The following topics are addressed:
- Introduction Self-cleaning Heat Exchanger Technology
- References Evaporators
- Different Evaporator Systems
- Maximum Concentration / Boiling Point Elevation (BPE)
- MEE; Design Aspects
- MVR; Design Aspects
Advantages of the technology
Improved energy performance
Enhanced production capacity
Sustainable process
Compact design
Please call or e-mail us for more information
Do you have any questions about our innovative technology and its applications? Please feel free to contact our office in the Netherlands for additional information. We will happily assist you via phone at +31 85 27 34 834 or via e-mail at info@klarenbv.com.
Improved energy performance
In a self-cleaning heat exchanger the tubes remain clean and therefore the heat transfer can kept constant which improves the energy performance:
- A shell and tube heat exchanger to cool quench water had a decrease in heat transfer coefficient of 50% within 20 days of operation. With a self-cleaning heat exchanger, the heat transfer coefficient remained constant.
- Because of the lower fluid velocities and shorter tube length in most applications the pumping power required is reduced. In the apllication mentioned above the reduction was more than 50%.
- Applying the self-cleaning fluidized bed technology for an evaporator that concentrates waste water allows to reach higher solid concentrations in the recirculation flow without incurring in fouling problems as compared to falling film evaporators. This results in a higher water recovery and a drastic reduction of the blow down. When adding a spray dryer to come to Zero Liquid Discharge the overall energy consumption of the self-cleaning unit combined with the spray dryer is only 60% of the energy consumption of the falling film unit combined with the spray dryer. Main reason for this is that with the technology of Klaren International the waste water can be further concentrated meaning a smaller volume flow as blow down requiring less energy for spray drying.
- A shell and tube heat exchanger uses water to recover heat from an exothermic reaction. The heat is used elsewhere in the process. Fouling on the chemical component side of the heat exchanger causes a decrease on heat transfer coefficient which results in a decreasing heat recovery capacity. As the fouling layer develops an increasing amount of make-up steam has to be used to further heat the process elsewhere. With a self-cleaning heat exchanger the heat recovery form the exothermic reaction remains constant and no steam has to be used.
Enhanced production capacity
A self-cleaning heat exchanger needs not to be taken out of production for cleaning, therefore the capacity remains constant and in some cases the production yield can be increased, which enhances the productivity:
- With fouling of heat exchangers the period between two cleanings can range from a year to 4 hours. In most cases cleaning means a stop in operation with as a consequence a loss of production. If a stop in operation is not allowed, it is usually decided to install redundant equipment. Choosing for redundancy means an additional investment.
- It is known that in case of fouling in crude oil pre-heaters, installed upstream the refinery furnace, the required inlet temperature of the distillation column cannot be met and thus the throughput needs to be reduced to meet the required inlet temperatures. Obviously, reducing the throughput directly affects the production output and the revenues of the refinery. With a self-cleaning heat exchanger there is no downtime for cleaning nor is it required to install redundant equipment and throughput can remain constant.
Sustainable process
When using the self-cleaning heat exchanger technology chemicals are not required as online additives or needed for cleaning purposes. Therefore, there are no hazardous waste streams from cleaning which makes the heat exchanger more sustainable:
- All MSF plants for sea water desalination use a chemical additive to suppress fouling or scaling of sea water in the condenser section or the top brine heater. Already in the late 1970’s at the Island of Texel a MSF plant with a vertical orientation has been built and operated that applied a fluidized bed in the tubes of the condenser and final heater and could run without the need of chemicals to prevent scaling.
- PTA coolers face a major issue of fouling. A major PTA producer has to clean the PTA coolers every 6 hours. Cleaning of these PTA coolers is done using chemical solutions i.e. caustic solution (5% w/w caustic @ 80 deg C). After cleaning they have to dispose the caustic solution which contains valuable terephthalic acid crystals. Replacing the existing PTA coolers with the self- cleaning coolers will enable the PTA producer to skip the caustic cleaning of the heat exchanger and thus there will be no disposal of the cleaning solution.
Compact design
Because of a constant heat transfer in the self-cleaning heat exchanger, over dimensioning of the heat transfer surface is not required which results in a more compact design of the heat exchanger:
- With a heat exchanger application known to foul, the required surface of the heat exchanger is normally calculated by adding a fouling factor to the heat transfer coefficient. Fouling factors can easily be 2 to 5 *10-4 m2K/W. Starting with an overall heat transfer coefficient of 2000 W/m2K, the heat transfer over time will drop to 1500 W/m2K or in the worst case to only 1000 W/m2K. So, for the same heat capacity, the heat exchanger needs an overdesign of 30 to 100% to meet the required capacity over time. With the self-cleaning heat exchanger overdesign is not required leading to a more compact design.
- Besides the scouring effect of the particles, the fluidized bed in the fluid stream has an additional effect. The chaotic movement of the particles also breaks down the boundary layer and thereby strongly improves the heat transfer with a factor of around 4 at the same fluid velocity. Because the self-cleaning heat exchanger normally applies lower velocities the heat transfer improves with around 20% compared to that of a regular shell and tube heat exchanger.
Contact us at:
Hanzeweg 35N
3771 NG Barneveld
The Netherlands
Phone: +31 85 27 34 834
Email:info@klarenbv.com
Any questions?
+31 85 27 34 834