Unipol PE related parameters

1. For reactor C4001, when should pressure control be based on partial pressure and when should it be based on total pressure? ? Are there any particular considerations? Reply: The control method for the normal reactor C4001 should be pressure division control; in case of issues with pressure division, it can be switched to total pressure control. For reactions, partial pressure control is relatively precise; therefore, the partial pressure control mode is recommended. Total pressure control is not accurate for reaction control, and it leads to instability in the components, which in turn affects control stability and product quality. 2. Where are the data on the partial pressures (mole ratios) of the various components within C4001 obtained from? (It seems that C4001 itself does not have sampling points for online analysis; there is an online sampling port at the outlet of the recycle gas compressor.) Reply: The data for C4001 is obtained through online chromatographic analysis. The sampling point is at the compressor outlet, as you said. The composition in the reactor is controlled by analyzing the components of the recycle gas through online chromatography. 3. Catalyst activity: How are the values of product per T/Kg of catalyst and reaction yield calculated? “ Is the formula ‘Active* catalyst flow rate Kg/h = Yield’ derived from activity to yield, or vice versa? Reply: The activity of catalysts varies depending on the type of catalyst. For the same catalyst, factors such as its concentration and TI content have an impact (I’m not sure if you use chromium-based catalysts). To calculate catalyst activity, parameters such as concentration and titanium content are also required; the formula \"activity * catalyst flow rate in Kg/h = yield\" cannot be used. 4. Exhaust gas recovery: Is it cost-effective to install a new membrane recovery unit? ? What is the membrane recovery process like, and is it complex? Reply: In fact, from a practical standpoint, the membrane recovery unit holds little significance in this process – it requires significant investment, the cost of replacing membranes is high, and its maintenance is complicated. Many customers find it difficult to achieve a satisfactory cost-performance ratio after opting for membrane recycling (aside from the desire to meet sales targets or generate publicity); it’s not as good as what the membrane recycling manufacturers claim. However, membrane recovery is indeed a useful technique, and it offers considerable economic benefits in facilities where there are many components to be recovered in large quantities. The process of membrane recovery is very simple; it involves a small device that makes use of the principles of absorption and separation by membranes. The above are just some of my personal opinions; I hope they can be helpful to you. We can keep discussing! If you’re satisfied, you can give it a best answer. Ha

The explanation upstairs was very detailed; I’d like to add that whether to use pressure division control or total pressure control depends a lot on the catalyst used. Those that are sensitive to partial pressure tend to use pressure division control, while our unit uses total pressure control； Yield is actually just a calculated value; it is related to many factors such as the flow rate of the circulating gas. When the flow meter malfunctions or the pressure guide tube gets blocked, the flow rate becomes inaccurate, and consequently the yield is also inaccurate. Of course, during stable production, the yield is quite close to that of the calibration. Catalyst activity is actually obtained by dividing the yield by the amount of catalyst used; it is a calculated value, and it is relatively accurate under stable production conditions. However, the true catalyst activity still needs to be calibrated.

There are some concerns regarding the response to exhaust gas recovery; if the device frequently induces condensation, it is more cost-effective to use a membrane separation system, as this reduces the amount of isopentane that needs to be added.