I am working on a continuous flow system for preparing solid products, and I need to keep the reactor under 100 psi pressure using a back pressure regulator at the end of the line. My problem is that this back pressure regulator has a small aperture and the solid material might clog it up, so I want to build up a system in which the flow is guided into a container filled up with solvent and equipped with an outlet tube where the back pressure regulator is installed, so as to allow the solid to deposit on the bottom of the container and prevent it from flowing through the back pressure regulator.
Anybody has any suggestion about the kind of container that might withstand at least 100 psi pressure and thus serve my purpose?
What temperature will you be using? The vessels in the following link should work, but they are made for "sanitary fittings" which are limited in temperature. The clamps should comply with ASME VIII - A24.
http://www.eaglestainless.com/bottles.cfm?product=asme
Dear Keith,
Thank you for your answer. In fact, there are no particular temperature issues, as the inlet tube is previously cooled.
Anyway, I would prefer having glass-like containers, so that I can see what's going on inside, any suggestion?
Since your system is totally different from regular flow system. Could you describe your system more detail.
1. Why you should keep your system under pressure, Whether your reaction is three phase reaction and you need to keep the pressure of gas phase, or you need to keep the pressure of system to prevent vaporization of solvent.
2. Why the inlet tube to back pressure regulator is previously cooled. It is not convient for process design. Wheather the crystallization occur after cooling.
Anyway, If you just want to prevent colg of regulator by solid material, you may use commercial available pressured vessel equiped with sight glass as the receiver which the capacity is higher than the quantity you need. Which the outlet of your system and back pressure regulator may be installed on seperate outlet port of vessel. You may use N2 as sealing gas for the vessel to keep back pressure out of containmination of reaction stream and solid product.
Dear Keh, the main reason why I keep the system under pressure is that working at 7 bar instead that 1 bar allows to increase the boiling point of the solvent (i.e. from 150 to 230°C for DMF), and consequently to expand the range of possible temperatures for the reaction I'm performing. In addition, I have noticed that, with the back pressure regulator on, the flow is more regular.
Regarding the second point you raised, I am synthesizing metal organic frameworks, for which crystallization occurs upon heating the reaction mixture, and the cooling have a negligible effect on the crystallization process.
Could you please provide a link or something else regarding the vessels you talk about?
The presured vessel I mentation just like the vessel use for supplying Coco Cola in vending machine. You should also design by yourself to provide the deviice of sight glass if necessary, and change the connection port for fitting your system tube .
From your description, The reaction occured when the reaction temperature had reachched, and the solidified reaction product was yieided.
The back pressure regulator just function as keeping system pressure allowed to expand the range of possible temperatures for the reaction. The solidified reaction product formed during reaction condition. So you can seperate your reaction product under the same pressure of reaction appratus. Th pressured evessel described above seems fit to your needs.
You may think about of changing your reaction solvent system to keep the whole reaction media soluable in solvent system, which the reaction could be operated homogenerous, and the product crystallized after the back pressure regulator when solvent vaporized.
Since continuous flow system usually use as mass production equiptment, I don't suggest you use the equiptment assembly by glasses tube thought it can be operate up to 150 psi. The failure of pressured glasses equiptment usually occur at joint of glass elements.
By the way, The reaction seems very convience from your description . May be you can try batch operation with pressured reactior, also equiped with back pressure regulator for system pressure control and avoid the run away of your system. You may find commercial available pressured reactor of glasses which you can monite the proceding of reaction.
Dear Maud, I had seen the ACE pressure tubes, but I was thinking about something a bit different, anyway they might be a good model for designing a custom-made vessel. As Keh notices, the problem with glass is on the joints, so it might be better to switch to another material.
Switching to batch synthesis is not desirable for me, the aim of the project is to develop a continuous flow system for massive production of MOFs with high space-time yield and I am not looking at batch conditions at the moment.
Dear Marco,
swagelok has pressure resistant containers. Other solution you might use backpressure regulators that are adapted to flow chemistry eg from Zaiput.
From my experience there is no simple back pressure regulator for solids in a flow system. Your idea of using a solvent reservoir is a good one and of course needs to be made to suit 100 bar and in addition should have pressure relief options. We use a Zurich approved pressure reactor that was developed the the University of Nottingham by Prof Howdle called PressureSyn.
We eventually solved the issue by employing a gas to apply the pressure in a simple glass collecting unit and installing the backpressure regulator on the gas line, so as to prevent any flow of reaction mixture through it. This allowed to safely operate the system up to 6 bar overpressure. See the attached publication for more detailed information.
Finer versions of the same collecting unit are described in ref. 33 and 34 in the attached publication.
Article Continuous-Flow Microwave Synthesis of Metal-Organic Framewo...
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