Frequently Asked Question

No, the orientation is always vertical. The continuous and effective self-cleaning process requires a vertical orientation of the heat exchanger tubes to have a good fluidization and distribution of cleaning particles over all tubes. In horizontal tubes the top of the tube would not be hit/cleaned by the fluidized particles efficiently. 

No, our long time operational experience has proven that the tubes will not erode or leak. As the slip velocity between the fluid flow and the cleaning particles is low, the impact velocities of particles with tubes wall are too low to cause erosion.

>Weight loss of stainless-steel particles is between 3 and 5% per year. At some moment in time the full amount of particles needs to be replenished because their size has become too small. This is around 7 years for stainless-steel particles. For ceramic particles the weight loss will depend on the selected grade of ceramic.

No, the mechanism that keeps the tube wall clean also keeps the particles clean.

The cleaning is a continuous process by the circulation and fluidization of the cleaning particles.

No, as the cleaning particles move within fluid flow, the amount of additional noise due to the movement of particles is neglectable.

The self-cleaning technology can be applied in a single pass vertical Shell &Tube heat exchanger. Revamp of a multi-pass conventional heat exchanger into a single pass self-cleaning heat exchanger is in many cases possible.

Typically, in a new built case ROI would be between 2 to 4 years. The ROI depends on client project, process and industry.

The rate of fouling removal is affected by the particle size, because the cleaning mechanism comes in effect with the cleaning particles hitting the wall. The strength of the impact is  determined by the kinetic energy of the particle, and kinetic energy is influenced by the particle mass.

Overall impact of the cleaning particles on the pressure drop  will be limited due to small amount of particles (i.e., porosity) as well as the low flow velocity that is considered in our designs. It should be highlighted that, the pressure drop will not increase in our self-cleaning heat exchangers due to the fouling of tubes, which will be the case in conventional heat exchangers.

The flow velocity is playing a major role in proper distribution of the fluidized particles in the tubes. Large flow velocity will result in scattered particle fluidization leading to in-efficient cleaning mechanism. Hence, we prefer to use tube velocities below 1 m/s, which not only guarantee a proper particles fluidization and effective cleaning, but also prevent erosion of the tubes. In many applications, like in forced circulation evaporators, a reduced flow can be traded against a higher temperature rise over the tubes maintaining the same capacity.

The pressure and temperature ranges for conventional Shell & Tube and Material of Construction (MOC) are comparable to those with the self-cleaning fluidized bed technology

For the separation we use, depending on the properties of the fluid, different type of separators: separation based on a sieve (mesh size smaller than size of the cleaning particles), separation based on gravity – and separation based on a cyclone. However, the gravity separator could be considered as our standard design for most applications. With a known design flow and a viscosity range we design the gravity separator taking into account certain safety factors. Based on Computational Fluid Dynamic (CFD) verifications and feedback from the operation of different plants we know that particle separation is up to 100%. Even particles from 2 mm will not escape when the separator is designed for 3 mm.

Yes, upgrading / revamping of the MEE units with self-cleaning technology will help to keep the evaporation capacity at the highest/designed level for a long time due to continuous removal of the fouling in the evaporators.

Depending on the application, there is some room for variation in flow rate, i.e. up to 20%. Higher or lower change in flowrate could affect the fluidization regime in the tubes negatively resulting in weak or ineffective cleaning mechanism.