Cooling coil selection
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For a new project of our company, there is an acid leaching reactor whose temperature is too high. The process requirements dictate that the temperature of the slurry, which is at 90 degrees, be reduced to around 75 degrees within half an hour. The volume of the slurry in the reactor is 25 cubic meters. Our management has decided to use titanium-coiled tubes for cooling, with cooling water taken from the cooling tower in the system; the inlet and outlet temperatures of this water are 42 degrees and 37 degrees respectively. Dear experts, how should we select the appropriate type of coiled tube for this purpose, and how should the calculations be carried out? What should be the flow rate of the cooling water?
To calculate the heat transfer area, simply select the pipe
The two fundamental equations for heat transfer are used first to calculate the amount of heat that needs to be transferred, that is, the heat that must be released to cool the liquid. The formula for this is Q = c·m·Δt; the specific heat capacity c can take the value of water, as it has the highest specific heat capacity. m represents the mass flow rate, and Δt is 90–75°C. After calculating the amount of heat required, an excess amount is taken into account, and then the required heat transfer area A is calculated using the formula Q = K·A·Δtm. K should be chosen as a value within the range applicable to coiled tube heat exchangers, with a smaller value being selected. Δtm represents the logarithmic mean temperature difference; in reality, since it’s a counterflow situation, the parallel flow formula can be used, which ensures a sufficient excess amount. Once A has been calculated, the required length of the titanium tubes can be determined based on the diameter of those tubes. Finally, depending on the specifications of the reactor, it can be determined how many times the tubes need to be coiled and in what manner.