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Minimum Flow System




My friend, In this posting we will discuss about the pump recycle systems. The pump shall be protected from minimum flow, due to the following reasons;
1. Thermal consideration which has effect to the pump efficiency (The efficiency will decrease significantly at low flow)
2. At low flow, Internal recirculation will be occurred
3. Increase load impeller (both axial and radial)
4. liquid containing a large amount of abrasive particles must flow continuously through the pump. at low flow, the particles can circulate inside the pump and erode the impeller.

Discharge Pump System



My friend, how are you today, ? I hope this weekend give us the best of everything ; find some good experiences, new spirit, and (may be) new planning for the better future, etc.
My friends, Let me share a simple material regarding the discharge pump system, but in this posting, I will only focus on centrifugal pump type. 

Reducer Suction Pump System



Generally, the pump inlet nozzle size is smaller than the suction line size. Therefore, usually, the reducer is required on suction pump nozzle. What the appropriate type of reducer should be applied ? Eccentric or Concentric ?

Pump Suction Strainer



For pump protection, inlet line suction pump should be fitted with a strainer. The strainer can be either T or Y type, permanent or only for temporary. For clean fluid service, such as; demineralized water, boiler feed water, etc the temporary strainer can be used..

Suction Pump Block Valve

Block valve shall be provided on suction and discharge line of pump. The block valve is required for isolation purpose during maintenance. In this posting, we will discuss about the block valve on suction pump. The block valve is not required for suction pump where pump maintenance can be performed without isolating the suction side.

System Separator

My friend, in this posting, I will share my experience in checking the typical separator system or pressure vessel system. This check list is only general rule or general engineering practice. as we know, each project has a specific requirements, so this guideline should be modified as per specific requirement.

Depressuring - Spreadsheet Method

In Hysys Depressuring utility, the model is only specified as one horizontal or vertical vessel. Dimension of that single vessel, is back calculated based on total liquid and vapour volume. Wetted area calculation is difficult for horizontal vessel. It is difficult to match wetted area and liquid volume of vessel with wetted area and volume of a system.

Depressuring Tutorial

In this posting, we will learn the depressuring simulation study using HYSYS simulator. The simulation is mainly divided into two steps, fire case and adiabatic case. Commonly, the fire case simulation result in the peak flowrate to flare, whereas the adiabatic case simulation is used as basis in determining Minimum Design Metal Temperature (MDMT).

Basic Depressuring - Why 15 minutes ?

In previous posting, we have discussed that PSV wouldn’t provide adequate protection for vessel of fire case. Therefore, depressuring can be applied for another safety layer.

Commonly the plant area is divided into the ESD Zone. Each ESD zone may contain one or more equipments. ESDV or SDV valves are provided in each ESD Zone to isolate the system zone. In case of fire, a system will be isolated by those SDV valves. Then the inventory fluid (commonly gas phase only) in the system will be released to flare through BDV valve. Commonly one BDV is provided for one system zone, but in some cases, it is possible to provide more than one BDVs in one system zone.

Relieving Condition Exceed Design Temperature

Equipment design temperature is usually determined based on the maximum temperature plus a certain margin. The margin could be different for each project, say 20F, 25 F or 30F. Conducting rigorous simulation for fire case, the temperature in each stage simulation is set higher than the previous stage by certain interval. Let say, using 10F in interval temperature will result in temperature about 30F higher than the operating temperature at third stage simulation. That is why; relieving temperature for fire case is very often higher than the design temperature. Whether or not increasing rating pipe is required?.

Useful HYSYS Short Cut

Hi my friend, in this posting, I just want to remind you several useful short cuts in HYSYS. Actually, It’s a simple material of training course for beginner. But, in fact, some engineers have forgotten it, although they have used HYSYS long time ago.
Got your HYSYS up and running? Just go to HELP/SHORT CUT KEY.
HYSYS provides many short cut, you can check it there.It very helpfull. Try it.

Rigorous Method for Fire Case

In previous article, I have explained that relieving load for fire case can be calculated as heat input divided by latent heat of vaporization. (W = Q/Hv). The heat input have been discussed before, see fire case –heat input rate. The latent heat of vaporization is rather difficult to be determined. During fire, liquid in the vessel will be vaporized, but the amount of vapor formed is not fixed, because the liquid composition is change overtime. In this article, I will explain you step by step the rigorous method for fire case

Fire Case - Heat Input Rate

Fire can cause overpressure of storage or vessel. Either liquid vaporization of wetted vessel or vapor expansion of unwetted vessel due to heat input will increase the pressure. Heat input rate of fire exposure is not calculable from standard of heat transfer fundamental. Fortunately, OSHA regulations specify standards which are to be followed for particular material in storage vessel and API also provides formulas for calculating heat input rate which are to be followed for particular condition of process vessel.

Reflux Failure Case

Reflux failure case is the major case of all tower or column. Reflux failure can be caused by the following:
- Power failure lead to reflux pump off
- Pump failure
- Control valve failure ( fail closed or stuck closed)
- Operator error etc

Tube Rupture Case

Tube rupture may be occurred for shell and tube heat exchanger type. Based on my experience, some design philosophy using 2/3 rule, and some other using 10/13 rule for the criteria of requirement PSV for tube rupture. Which one is correct? Should we apply 2/3 or 10/13 rule?

Blowdown PSV

I can't sleep again, till this midnight , almost 00.00 PM (or AM ? ), I just confuse what to do. I think it will better for me to do something useful. But what ? I don't get any idea. Until finally, I remember this blog.
My blog save my brain :D.

Gas Blowby Case

Gas Blowby is the discharge of gas from a process component through a liquid outlet. It can be caused;
- Failure of a liquid level control system.
- Or in advertent opening of the control valve by pass.

Block Outlet Case

My friend, regarding the overpressure protection system design, one of important responsibility for process engineer is determining the cause of overpressure. In this posting, we will discuss whether a kind of case is possible occurred.

Accumulation and Overpressure

In this posting, we will discuss about pressure level related to relief valve, especially the difference between accumulation and overpressure. Those two terminologies (accumulation and overpressure) often cause some engineer confused.

PSV Sizing

Sizing of pressure relief valve is clearly explained in API STD 520 part 1. Some formula is provided for calculation the orifice size either for vapor or liquid application, critical or non critical condition.

Built Up Back Pressure Calculation

My friend, do you still remember? One of consideration in selection of relief valve type is built up back pressure. In this article I will explain you how to calculate the built up back pressure. Oh, do you still remember what is built up back pressure? Is it a constant or variable?