Chemical & Process Technology: What type of heat exchanger can be used to handle fluid with solid ?

Tuesday, July 31, 2007

What type of heat exchanger can be used to handle fluid with solid ?

Above question started with a simple query raised in the Chemical Resource Forum.

"Plate Type Heat Exchangers V/s STHE - We are planning to replace an existing Shell & Tube HE with a Plate Type HE as the existing one is not offering the desired effect. The duty of the HE is attached. Since one of the fluid handled contains solids, can a PTHE handle it? I would like to know if similar retrofits have been carried out and what are the precautions to be taken while opting for such a change ? "

How do you interprete above question from engineer perspective ?

How do you interprete "fluid handled contains solids" ?

The process may contains solid can be
(a) high concentration, small particle size or;
(b) high concentration, large particle size or;
(c) low concentration, small particle size or;
(d) low concentration, large particle size

Above combination may end-up with different heat exchanger which best suit their own need. Thus, whenever specify solid in fluid, concentration (wt% or ppmw) and particle size (micron or mm) are required to be spelt out so that other (vendor , consultant) can provide the most cost effective solution whilst meeting process demands.

Can PHE take fluid with solid in it ?

PHE is having a very unique feature where narrow channel and proper engineered cross-sectional areas promote turbulence and high heat transfer (convective) capabilities. High turbulence has the potential of removing scale stick on the plate. However, present of solids in fluid promote pluggage in the narrow channel and ultimately results NO flow.

(Click image for better view)

What are the option can be suggested here ?

Probably first and ordinary option is relook into the root-cause of under-performed STHE by analyses the STHE construction, review maintenance frequency and methodology, etc and check if there is oppurtunity to modify existing STHE to increase heat exchange performance.

Somehow if it has to be replaced, there are some type of heat exchanger which properly suitable for "fluid contain solids". There are :

Spiral HE (Alfa Laval , Sentry)
Self-Cleaning HE (KLAREN)

Further reading :