As suggested by their name, the heat transfer between the primary and secondary fluids is done, in these recuperators, by convection.

Their main feature is the full contact between the gases and the tubes composing the recuperator, so that they are especially suitable for the following cases:

  • For working temperatures lower than 1.000 - 1.050 oC.
  • For quite clean gases streams (with no particles) and without especially corrosive components.
  • An accurate thermal rating succeed in getting the best relation between the exchange surface and the pressure drop, as well as between the exchange surface and the engaged space.

    All that, together with the consideration of the risk of corrosion and the knowledge of the facilities where they will be placed, vouches for the use of the most suitable equipment to meet our customers' needs.

    Besides that, the best choice of materials vouches for a long life of the equipment and an excellent relation between quality, price and efficiency.

    Finally, the specific choice and calculation of each recuperator succeed in getting the best energy recovery with a so important saving that, most of the times, the investment for the equipment is repaid in a short period.

View of a set of tubes bundles

Channel type convective recuperator

Channel type

KALFRISA S.A., as a result of being 30 years experienced in the design and fabrication of recuperators, has developed a high number of technical solutions to cope the needs of its customers.

There are two types among these recuperators:

  • Tubes bundle recuperators without frame, to be introduced in a horizontal gases channel (be it underground or aerial) or in a vertical one (a stack).
  • Tubes bundle recuperators with an interiorly lined frame, for those cases where there is not a defined gases channel (be it horizontal or vertical).

Besides that, for those cases where a maximum thermal profit is intended, it is possible to look for technical solutions by combining two or more recuperators, both parallel and series-connected.

These equipment are especially applicable in several sectors such as the steel industry (roasting and reheating furnaces, and wind stoves in blast furnaces), mineral industry (calcining and burning kilns), incineration plants and drying of sludge coming from water cleaning plants, etc.

Channel type recuperator with six tubes bundles. Horizontal gases / Vertical recuperator

Recuperator with four tubes bundles and frame. Vertical gases / Horizontal recuperator

Heat exchangers

Like in a channel type recuperator, the heat transfer is done, in a heat exchanger, by convection.

These equipment have a more compact design that provides a quick and easy erection.

In a heat exchanger, the tubes bundle is built in the frame containing it. In order to avoid possible cracks that may result from different thermal expansions between the tubes bundle and the frame, some compensators are installed or some tubes of the bundle are bent.

These equipment are suitable for the following cases:

  • When the flue-gases temperature is not too high, around 700 - 750 oC., except for special cases.
  • When a channel is not available for the tubes bundle to be introduced into.

Range of application of these heat exchangers is really wide, being especially suitable in plants for solvent incineration in the automobile industry, in co-generation plants, in metallic and plastic surfaces treatment plants, etc.

Three steps heat exchanger at counterflow

Three steps heat exchanger at counterflow

Two steps heat exchanger in parallel flows


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