Adiabatic dry cooling in steel wire drawing

We’re working on an interesting application for industrial cooling in the wire drawing process in the steel industry. In particular, the process requires cooling with water at a temperature of 25-28° C.

This is a peculiar temperature range, because this is not low enough to justify the implementation of a chiller. The application involves indeed the dissipation of several hundreds of thermal kW, and a chiller should require high costs for the machinery, first of all, and then high amounts of power absorbed, especially during the warmer season. On the other side, the temperature levels involved are too low to be satisfied using a cooling tower, especially during the warm season, even though offering very low energy consumption. In addition, being a cooling process with direct contact with the product, the water of a cooling tower has to be treated with chemicals, anti-algae, anti-bacterials and anti-limescale, thus not compatible with the product itself.

Facing this doubts, an ideal solution would be to employ a thermal machine with water in closed-loop, but we should adopt an evaporative tower combined with a heat exchanger, and furthermore we won’t obtain water at a suitable temperature.

The solution we offered employs closed-circuit adiabatic coolers, or adiabatic dry coolers. These are dry coolers with an adiabatic booster, that during the summer season employs a spray system on the air drawn into the cooler by the fans, creating a sort of ‘evaporative tower’ effect. The reference temperature is thus the wet bulb temperature, involving a low water consumption for evaporation, limited to the warmer hours of the day, in the warm season only. The system ensures to have water at the temperature of 25-28° C during the entire year, also during summer, avoiding direct contact of the water with ambient air.

 

Our system allows in particular very low water consumption, limited to the warmer months, not scaling nor clogging the finned coil of the exchanger. This systems ensure very high levels of efficiency, achieving cooling by using closed-circuit water with temperatures that are halfway those achieved by chiller and cooling towers.

As usual when engineering this kind of plants in Tempco, the system has been obviously equipped with an inverter on the fans. With ambient air at our latitudes, indeed, during winter and the mid-season, spring and autumn, water at the temperature of 25° C is very easy to obtain. Having fans working at their maximum speed is thus useless, and the adoption of an inverter can deliver high energy savings.

An evaluation made with the customer forecasts that the consumption of water will be limited to only two months per year, and probably only during the warmer hours. The facility also works over three shifts, and overnight the consume of water should be near zero, if not even completely avoided, also probably with a reduction of fans’ speed.

Finally, we’ve implemented a remote monitoring solution, in order to control the effective water consumption and the amount of energy absorbed by fans, looking forward to a future optimization of the overall process, in which the company is planning further investments. The gathered data also offer advantages for both of us, improving the engineering and proposal phase in Tempco, and for the customer, that can have full transparency and awareness on its thermal energy and power needs. Being also able to make an energy accounting and to evaluate the savings that can be achieved.

 

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