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In the previous post, I forgot to mention that centrifugal compressor has been assumed. It is not valid for reciprocating compressor. In this case the power will be less.

It depends on the power is calculated for a compressor in design phase or the compressor has been built and now to be operated with a gas with higher MW. If in the design phase, the higher MW gas will result in lower power (with the same temperature, pressure and volume flow rate). The reason is...

After the run, righ click on the stream and select copy. Then select the same stream, righ click and select past special/total stream composition.

In my first email, the suction pressure was given at 20 bar. It is typical pressure from PSA units. One or two stages reciprocating compressor was used for the most of units, I have seen. I have just wondered that no of them was a screw compressor.

Gentlemen, I don’t agree that centrifugal compressor would be suitable for this service. The high compression ratio and the low molecular weight (2-4) will require very high head compressor. I give an example for the case with 99% hydrogen gas. The head is 1430 to 2650 kJ/kg or 480,000 ft to...

Sorry, I meant rotary screw compressor

In hydrotreating process, the make-up hydrogen is supplied by a make-up compressor with discharge pressure in the range 50 to 90 bar. Suction pressure is around 20 bar. Gas purity is 90% H2 or higher. All make-up compressors, I have seen are of reciprocating type with a stand-by machine. The...

Thanks for the quickly reply. First of all, I’m sorry for my typo mistake. It should be div.1 for this low pressure vessel. Of course, the specification will be through a third party company. But we as the end user might have responsibility to inform the 3rd party about this information. I...

I need some guidelines to make specification for a distillation column. The vessel shall be designed according to ASME VIII div. 2. Design pressure is 8 bar and design temperature is 250 deg.C, , material is CS. As a consequence of a up set condition, the vessel could be filled up with liquid...

The selection is dependent on many factors. Suppress boiling give high outlet temperature, which may require a pressure higher than the available pressure. Design pressure of heat exchanger will be higher. Heating medium must have higher temperature, which may not be available. Of course two...

The heat transfer area A is calculated as: A = Q / U / LMTD With back pressure the outlet temperature will be high, which lowers temperature difference LMTD. Convection heat transfer coefficient U is normal lower than vaporisation U. Heat transfer area is therefore larger with back pressure...

Sorry, I made a confusion, I real mean the discharge pressure is dependent on gas properties. I mean that the discharge pressure in this system is controlled indirectly via the condenser outlet temperature. What happen when both outlet temperature of fin fan and CW cooler goes down, e.g by 5...

A background of alkylation process may help to understand the system behavior. In alkylation reactor, C3/C4 olefins react with isobutane to make a high octane gasoline. The process is catalysed by a strong acid like sulphuric acid. The process requires low temperature (0-5 deg.C) and high...

I don’t think the design temperature & pressure and required material prohibit the use of butterfly valve in this application. The standard system provided by some vendors in the above links is for low temperature and pressure and with some limited material. But the same principle can be applied...

I would like to clarify that the operating fluid is at 60 bar and 350.C. These data would affect on material selection, thickness of body and sealing. The pressure drop across the valves shall however be as low as required for a properly size.

Thanks for valuable input. The valves from Leslie (RVK, GTW or DOT) could be a solution to my design. I will investigate further together with mechanical link system. My control system will be operated at 60 bar, 350 deg.C in hydrogen and H2S environment. Material for the valves shall be...

Thanks for your reply. The control valves in the question should allow the bypass varied from 0 to 100% in different operating cases Is there any risk that both valves closed at the same time caused by actuators failure? In this case, a PSV should be installed to protect equipment upstream the...

Hi all, I design a temperature controller for a heat exchanger. A by-pass line around one side is used to control the outlet temperature. The size of the main line and bypass line is large (14"), such as a three-way valve is not desired. A layout with two butterfly valves is suggested. But...

This is an interesting subject. Let us forget all practical issues and concentrate about the simulation result. Two product specifications are specified. The two variables are reboiler and condenser duty. The simulator will try to vary reboiler and condenser duty until the two given...

I'm working in a project to find a way to increase the capacity of an amine absorber. The amine absorber is installed in a diesel HDS unit to remove H2S from the recycle gas. In the future, sulphur in the feed will increase by 50% and the H2S amount to be removed is expected 50% higher. The...