Urgent! Urgent! Urgent! Could you help calculate roughly how much heat exchange area is needed? ?
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The nitrogen flow rate is 2000 m3/h; the temperature is 100°C and the pressure is 10 kPa. It contains 10,000 mg/m3 of butadiene. After passing through a first-stage circulating cooling water system, the temperature is reduced to around 40°C, and then it goes through a second-stage cryogenic cooling process to reach around -10°C, thereby cooling down the butadiene. Could you also help calculate the approximate area required for the first-stage and second-stage heat exchangers?
The material of the heat exchanger and the specifications of the circulating water are not specified
The heat exchanger can be calculated using 304 for the supply water and 32 for the return water
The solvent content is very low, with nitrogen being the main component; what type of heat transfer element is planned to be used under these conditions? The design of conventional light tubes is relatively large; if internal fin heat exchange is to be considered, other design parameters also need to be verified. Please leave your contact information on site for further communication.
Are you sure that -10°C is sufficient for cooling? With such a high nitrogen content and a very low butane content, the partial pressure of the butane gas component is also low; as a result, the dew point is low as well. A low temperature is required for condensation. According to ASPEN simulations, with a content of 20 kg, -60°C is needed in order to cool down 19 kg
It has nothing to do with voltage division, right? At a certain temperature, the saturated vapor pressure of butane must be constant, right?
At a constant temperature, the saturated vapor pressure remains constant; at -10°C, the saturated vapor pressure of butane is 1.7 kPa. However, in a mixed gas, the partial pressure of butane at an absolute pressure of 110 kPa is quite low, amounting to 0.4 kPa based on the composition of the gas. Since this value is lower than the saturated vapor pressure, condensation does not occur. If it were pure butane, it would definitely condense at 110 kPa. But since the gas phase contains a large amount of non-condensable gas, N2, the pressure of butane is reduced. To achieve condensation, either the temperature needs to be lowered further to reduce the saturated vapor pressure, or the pressure needs to be increased to reach the saturated vapor pressure at -10°C
It’s obvious that the circulating water cannot be condensed; it’s unlikely that the chilled water will cool down either. With such a low initial partial pressure, it’s simply impossible for everything to cool down completely. Cryogenic cooling might work a bit better.