COMBIFLEX type recuperators are a very interesting alternative to radiation recuperators (double shell and tubes cage types) since their double thermal system provides a large surface of exchange whilst taking a minimum space.
These equipment consist of a double shell and a tubes bundle, placed inside the recuperator, in such a way that the secondary fluid circulates in parallel flows in one case and at counterflow in the other case, or vice versa.
When the secondary fluid circulates as above mentioned, the logarithmic average temperature is higher, so that they will need less surface of exchange to get a certain thermal efficiency.
These units are then smaller, if compared to other kind of recuperators, and reach the same thermal efficiency.
Heat exchange is done by radiation in the double shell, whilst in the tubes bundle it is done by both radiation and convection, due to the arrangement of the tubes.
The main advantage of this kind of recuperators is their high heat exchange capacity, as a result of their double and inverted thermal system allowing to reach high preheating temperatures even if the gases are not very hot; with practically no pressure drops in the gases circuit.
Besides that, we can also remark the following advantages:
- Compact design, which facilitates its installation.
- Lower request for space if compared with other kind of recuperators.
These recuperators are especially suitable for the following cases:
- Heart furnaces.
- Treatment furnaces.
- Solid wastes incineration plants.
- Chemical industry plants.
CAPACITIES AND MODELS
COMBIFLEX type recuperators are able to work with flue-gases temperatures up to 1.300 oC and air preheating temperatures up to 650 oC.
We have constructed equipment to preheat air flows between 300 and 32.000 Nm3/h although, under certain conditions, an equipment could reach 50.000 Nm3/h.
For small equipment, inside tubes bundle consist of only one row of tubes which are only once bent; for bigger equipment tubes bundle is double or triple and the tubes are twice bent.
Most of times compensators are not necessary to absorb the eventual expansions, even though it is possible to install them in the inside or outside shell of the recuperator.
Depending on the data of the thermal efficiency intended, etc., inlet and outlet manifolds will be close to the gases inlet or outlet.