Why can’t the heat exchange area of the alcoholization preheater be increased? In this way, the heat is reduced to around 20 degrees?
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Our factory uses the alcoholization system provided by Hunan Anchun Company. In this alcoholization system, the inlet temperature of the cold air in the preheater is 20 degrees, while the outlet temperature of that cold air is 145 degrees. The inlet temperature of the hot gas in the preheater is 165 degrees, and the outlet temperature is 65 degrees. To reduce the heater outlet temperature by 65 degrees, an alcoholized water cooler also needs to be added. My question is, why can’t the heat exchange area of the tubes in the preheater be increased, so that the temperature of the gas exiting the preheater can be reduced to 20 degrees through heat exchange? This means one alcoholation water cooler is eliminated, one piece of equipment is removed, and the hassle of maintenance is reduced. Why not do it? Why? Similarly, in other systems such as purification systems, it is often not possible to reduce the temperature of hot air to the inlet temperature of the cold air; therefore, water coolers and other cooling devices must be added. Why is this all the case?
Personal opinion: The cooling effect of a preheater cannot be increased indefinitely; 65°C is likely the theoretical optimal temperature for heat exchange. To achieve a lower temperature, the required heat exchange area would need to increase significantly. The advantage of water coolers is their low cost and effective heat exchange capabilities, but they are not suitable for handling high-temperature media – they are only appropriate for use with low-temperature media. Gradual cooling is the best approach for ensuring the long-term operation of the equipment. If the water cooler is removed and the heat exchange area is increased, the temperature difference between the incoming and outgoing materials will become too large, which could lead to a rapid reduction in the service life of the preheater equipment
What the brother said is also very accurate; his analysis makes perfect sense. In most workshops, most heat exchangers are followed by water coolers; there is no solution that can be achieved in just one step. I think it might be for the reason you mentioned. I also have doubts: the water coolers in my factory, all kinds of them, keep breaking down frequently. Leaks occur as soon as the machine stops running, and if that doesn’t happen, the coolers simply need to be replaced.
1. The water quality of circulating water is very important; poor water quality can easily lead to blockages and corrosion in the heat exchanger tubes. Therefore, it is necessary to increase the frequency of water replacement, apply chemicals appropriately, and use techniques such as bypass filtration to improve the management of circulating water quality； 2. To enhance the quality of the water cooler based on the medium used, measures such as internal anti-corrosion treatment and regular cleaning of the tube bundles can be taken to improve the efficiency of the heat exchanger itself ； 3. Strictly control the operating conditions, strive to avoid operation at excessive temperatures or under excessive load, and take strict precautions to prevent damage to the equipment caused by pressure buildup or improper operation.
Preheaters are quite common in chemical plants, but malfunctions are almost never seen.