Pioneer in Desublimation

Switch Condensers

Since the invention of the Switch Condenser in 1954 we have delivered about 1500 Switch Condensers worldwide. We have continuously developed the mechanical as well as the process design of the Switch Condensers. In particular, we have adapted the special designed fin tube system composed of rectangular fins to the newest requirement of the PA process, mainly to the increasing feedstock loading of the air.

Kelvion Desublimator
Kelvion Desublimator
Kelvion Desublimator
Kelvion GasKat
Kelvion Liquid Condenser
Kelvion Switch Condenser

The most important process key figures of the newest switch condensers are:
gas flow:          max. 40,000 Nm³/h
capacity:          max. 10,000 kg PA/cycle
efficiency:        min. 99.5 %
oX-loading:      100 g/(Nm³ air) and higher
Feedstock:      o-xylene, naphthalene or mixed feed
The design philosophy of our switch condensers is the optimal use of the entire installed surface for collecting PA. For that reason, we have introduced three sections of fin tube systems with different designs and functions.

The main task of the High Density Section is collecting PA in a very compact form. The High Yield Section is not only for PA collecting but also for gas cooling. Finally, the High Efficiency Section has a special filter function for PA needles, which guarantees the very high efficiency of our Switch Condensers.

  • High efficiency
  • Long lifetime
  • Low weight
Get in touch with Kelvion in United States of America Or give us a call +1 800 774 0474
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With small and ultrasmall substance streams separation using desublimation is a convincing economic solution. The desublimator range for this application category can be designed for gas flows of between five and 2000 kg per hour. In contrast to larger models no fin tubes are used here, but lamellas to permit a particularly compact design and a heat exchanger surface area above 200 square metres. The Mini-Desublimator is a customized product. As both design and manufacturing are by us, customer requirements of whatever kind can be integrated into the product. Mini-Desublimators are deliverable in all weldable materials.

In the Mini-Desublimators a gas mixture comes into contact with cooled lamellas. Here that part of the gas mixture to be separated desublimates either around or below its triple point and adheres to the cold surface in crystalline form. The Mini-Desublimator is split into several sectors to prevent too much of the substance being deposited close to the gas inlet. A range of lamella designs are available for optimum utilization of the heat exchanger surface - and the sectors are adapted individually to each process requirements to achieve optimum results, i.e. separation efficiency of over 99.5 percent.

The desublimated product is melted off as soon as the desublimator is fully loaded. A continuous process is possible by using a minimum of two Mini-Desublimators. At the same time is also possible with minor design adjustments to feed separate gas streams into a single Mini-Desublimator, using only one common cooling/heating system.

Despite the wide range of design possibilities and internal fittings the Mini-Desublimators are available in standard sizes. Thanks to its compact design the unit does not take up much space. Mini-Desublimators can be supplied in all weldable materials and can be used across a wide temperature range of between -20 and 350 °C, the pressure range is between vacuum and 10 bar.



"Clean" process: no use of chemicals, no water consumption
Excellent separation rate of over 99.5%
High product purity
Low space requirements due to compact design
No moving parts: low wear, high operational reliability, virtually maintenance-free
Flexible design

Liquid Condenser

The Liquid Condenser (pre-condenser) for the PA process was invented in 1989 in co-operation with Lurgi. Since then, we have delivered about 20 liquid condensers for PA plants worldwide. Nowadays, the liquid condenser is standard equipment in all new and modern PA plants.

In the liquid condenser PA is collected in continuous operation instead of batch operation of switch condensers. Therefore, in the total PA plant only one liquid condenser is required upstream of the switch condensers.

The design philosophy of our Liquid Condenser is to ensure that the maximum amount of condensable PA is collected in liquid form. For that reason, condensation occurs at temperatures just above the triple point. In order to avoid desublimation inside the liquid condenser temperatures of the cooling medium and casing have to be exactly controlled.

The most important process key figures of the newest Liquid Condensers are:
gas flow:                    max. 150,000 kg/h
efficiency / capacity:   all PA above 62 g oX/Nm³
oX-loading:                up to 120 g/Nm³ air and higher


In some PA plants post reactor technology is installed to improve plant performance. The conventional post reactor technology has separate vessels for gas inter-cooling and catalytic post reaction and thus is extremely space consuming.

The much more intelligent solution is the patented GasKat, which combines up to three process steps in one common casing:
controlled gas inter cooling
catalytic post reaction
subsequent gas cooling


modular and compact design
low invest and operating costs
low gas side pressure drop
easy catalyst replacement
small gas volume (i.e. low risk with potentially explosive gases)

Gas Cooler - Gas Heater

We design and manufacture so called cassette gas coolers and heaters, which are classified by the design concept "gas around the tubes".

Depending on the application, the unit consists of a common casing that contains different heat exchangers in modular design. The use of fin tubes provides larger cooling areas using the smallest volume. The main features and benefits of the cassette heat exchanger are:

Lower operating costs
Higher operational reliability
Very compact design
Low gas side pressure drop
Easy maintenance due to modular design

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