Heat exchange in high-viscosity media is a challenging task. Sulzer offers a wide range of expertise in the field of thermal energy exchange for your polymeric system. With our static mixing equipment, we guarantee a smooth and efficient heat transfer both out of and into your polymer.
Sulzer has extensive experience in designing and fabricating various types of mixer-heat exchangers for different applications. The SMXL mixer-heat exchanger typically divides the main product stream into sub-streams flowing through parallel tubes (multi-tube heat exchanger principle), whereas the product in SMR type heat exchangers is not split, but flows on the shell side of the apparatus, which makes this device ideal for reactions where residence time is a key factor.
The product conveying inner-tubes are filled with static mixing elements, creating a radial mixing effect. The result is a considerably increased heat transfer and a narrow residence time distribution, making it possible to achieve a short residence time in the heat exchanger. A continuous renewal of the thermal boundary layer on the piping wall prevents thermal damage of heat sensitive products.
Schematic drawing of the Sulzer SMR™ heat exchanger with the polymer stream flowing on the shell side and the heat transfer medium through the tube bundles
SMR and SMR plus mixer-heat exchanger
The SMR type equipment is not only suitable for heat transfer applications, but also for reactions where simultaneous mixing and heat removal is of great importance. The static mixing elements are made from tube bundles with a geometry which creates radial mixing of the product flowing on the shell side. Within the tubes of each bundle, heat transfer medium is circulated at high throughput. The SMR can be designed as a cross, co- or counterflow heat exchanger. Due to the radial mixing over the entire cross-section of the apparatus shell, the SMR is ideally suited for reactions where good mixing, efficient heat transfer and narrow residence time distribution are important. In addition, using an SMR type cooler prevents maldistribution, which frequently occurs with multi-tube heat exchangers.
Cooling a polymer melt or solution is a difficult task, as the viscosity of the product between inlet and outlet increases. In some cases, this effect may be very pronounced and can lead to maldistribution of the polymer flow between the tubes of a simple multi-tube heat exchanger. Sulzer has extensive know-how in predicting such effects by calculation and, by choosing the most appropriate equipment design, is able to find solutions for even the most difficult cooling tasks.
Cooling tasks typically comprise:
Cooling of silicone oil and silicone rubber prior to filling
Cooling of hot melt, adhesive solutions and thermoplastic melts
Cooling of polyester melt prior to fiber spinning
Adjusting the viscosity prior to a downstream process step
In most cases, polymer solutions are very sensitive to excessive heating. Accordingly, heating of such a product should be carried out within a short time and with a narrow residence time distribution, in order to maintain good product quality. Furthermore, hot spots, or overheated surfaces due to film built-up within the equipment, must be avoided to prevent damaging the product.
Sulzer's SMXL heat exchangers are optimally suited to fulfill this requirement. We can design these types of heat exchangers for mixtures of 2 or more phases, which may occur upon pre-heating in combination with large pressure drops within the equipment, for example, prior to entry in a devolatilization vessel.
