Aspen HX-NET heat exchanger network design problem
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I encountered some problems while using Aspen HX-NET for heat exchanger network design, and I would like to ask everyone: 1. How can I make the transition from my process flow simulation to designing the heat exchanger network using Aspen HX-NET? Should the heat exchanger be drawn first? But before I designed the heat exchange network, I wasn’t sure which stream this one should be matched with. All I know for now is that my flowing mass needs to change from one temperature state to another. 2. For components such as the reboiler at the bottom of the tower and the condenser at the top, where the fluid is vaporized or liquefied, the issue of latent heat of vaporization or liquefaction comes into play; this value should represent the heat load of the reboiler or condenser, right? When entering the information for each stream in HX-NET, how should the temperature of streams such as the overhead condensate be determined? For example, the temperature of the condensate at the top of my tower is 120 degrees. Theoretically, the temperature of the gas before condensation should also be 120 degrees. However, there must be a difference of at least 0.001 degrees between the inlet and outlet temperatures of the flow. So, what should be the appropriate value for the temperature of the gas before condensation? 3. If two grips appear, should the design take those two grips into account? Matching that is not at a junction point is relatively flexible, but even without any engineering experience, I’m still confused... Thank you everyone!
I don’t know how the original poster resolved these issues; these are the problems I encountered while just starting to use Aspen HX-Net. I think it depends on how you simulate it. For some processes, it’s not possible to replicate them entirely in Aspen Plus; instead, a certain reactor or operational unit must be used to simulate the actual process. It depends on the degree of accuracy of your simulation. If it matches the factory process exactly, with each piece of equipment corresponding to its counterpart, then things are simple – you can just follow the instructions in the user manual ； But sometimes it’s not exactly the same, so it’s necessary to use actual logistics data from real factories in order to calculate heat capacity and flow rates; this is a very complicated process. In my opinion, it becomes even more difficult when one gets the concepts wrong from the start. It’s not enough to simply know the temperature change from one value to another~ The latent heat must also be taken into account, as it represents a significant amount of heat! There are two pinch points; I haven’t encountered that situation before. Usually, there is only one, unless you divide the processes or units into separate parts, in which case there will be two~
Reply to 2# dingdangweiwei: Now I import the data directly into Aspen Plus. Do I still need to enter values for latent heat, heat capacity, flow rate, etc. manually? Also, for HTC, do you use the default values directly, or do you look up information and enter them manually?