chemical engineering: June 2010

Monday, June 7, 2010

Quick Estimation of Frictional Loss in Water Network - Spreadsheet Available

Recent post "Quick Estimation of Frictional Loss in Water Network" has presented frictional loss estimation using Hazen-William equation. Ankur has recently programed it in Excel spreadsheet. You may download with by clicking this link. Any comments, please drop a notes...

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Thanks to Ankur

Sunday, June 6, 2010

Quick Estimation of Frictional Loss in Water Network

Firewater, service, portable and drinking water network is common network present in most Oil & gas, Refinery and Industry plant. Water balancing in this network is important and critical in maintaining a constant supply to all users. Correct frictional loss estimation within network is the key activity in providing a well balance of water supply. Hazen-William formula is one the method widely accepted and used in industry in estimating frictional loss.

Hazen-William frictional loss is a function of fluid velocity, hydraulic radius and a constant subject to fluid condition and type of pipe. Equation as follow :

C Change with Pipe Material

Hazen-William friction loss coefficient (C) subject to condition and type of pipe. It possibly range from 60 to 150. The following summary listed the Hazen-William friction loss coefficient (C) for different type of material

(source : Handbook of Chemical Engineering Calculation)

Another set of Hazen-William friction loss coefficient also listed in NFPA 15-2007.

(source : NFPA 15-2007)

From above figures, the C factor is almost decrease with surface roughness.

C Decrease With Service Life

One shall take note that Hazen-William friction loss coefficient will decrease with service life. From King & Crocker "Piping Handbook", C = 120 when the pipe is new and decrease to C=90 after 20 years. From "Handbook of Chemical Engineering Calculation", C factor for a new Cast-iron pipe (30 inches) is 130, decrease to 120 after 5 years, decrease to 115 after 10 years, decrease to 100 after 20 years, decrease to 90 after 30 years, decrease to 80 after 40 years and decrease to 75 after 50 years.

An excel spreadsheet prepared by Ankur is under reviewed. Find out in "Quick Estimation of Frictional Loss in Water Network - Spreadsheet Available".

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Process engineering design involve preliminary equipment sizing during initial conceptual phase. It is mainly to identify the magnitude of major equipment potentially install in a plant. This is rather important during conceptual phase as equipment dimensioning will provide sufficient key information for budgetary costing which possibly provide direction in Process Engineering Design.

Process simulation is commonly conducted for all phases of design e.g. Preliminary Design, Basic Design, Front-End Design, Detailed Design, etc. Process simulation enable production of heat and material balance and provide basic process parameters for equipment specification and sizing. Conventionally equipment sizing is conducted manually and vendor preliminary sizing program / software. Transfer of process parameters to vendor software or spreadsheet will require time and effort and also subject to erroneous risk of data transfer. Therefore Process Simulation provider have taken extra effort to provide additional equipment sizing utilities in the Process Simulator to aid Process Engineer to identify system capacity and rule out technical not feasible process option. ASPEN HYSYS have done the same to assist user.

The following document is a HYSYS SIZING guide which provide information in using Sizing Utilities and provide the theories and equations used in the sizing Utilities. It is particularly important for an HYSYS Sizing Utilites user have clear understanding of the utilities background and limitation.

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Related Topics

HP June 2010

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Select Articles from the June 2010 Issue

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How will carbon emissions regulations revise energy conservation economics?

Including the cost of carbon in refinery project economics has the potential to convert previously marginal energy project into more attractive options

Low-cost advanced process control project captures energy savings in utilities area

This low-cost project resulted in over $300,000 per year in benefits

Modify your vacuum-tower transfer line to increase benefits

Designing the vacuum unit is a challenge. Revamping the transfer line can make this unit more profitable.

Advanced process control: quick and easy energy savings

Here are some of the energy savings benefits routinely produced by implementing advanced process control

Consider low-voltage AC drives for hazardous areas

Massive Such drives used with electric motors can offer significant process improvements and energy savings for equipment used in explosive zones

Trading silicon for carbon: how to reduce energy usage through automation

The average plant can conservatively achieve 15% energy savings through this technology

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Internal heat integrated distillation columns

Process Intensification (PI) is an approach to develop an innovate systems and practices offer a drastic reduction in chemical and energy consumptions, improvements in process safety, decreased equipment volume and waste formation and increased conversions and selectivity towards desired product(s). More detail discussion on PI has been presented by P.J. Lakhapate in "Process Intensification".

Another approach was introduced by R.S.H. Mah and co-workers is internal heat integrated distillation columns (iHIDiCs). It is common known that distillation is an energy intensive separation in particular those mixtures with very llow relative volatilities. Typical mixture systems are propylene-propane, ethyl benzene-styrene systems, etc. Several method such as thermal coupling, heat integration, vapor recompression and heat pumps were used to reduce energy consumption and improve distillation efficiency .

In vapor recompression designs, the vapors leaving the top of the distillation column are compressed and then are condensed in the reboiler of the same column, providing the heat needed for vapor generation. Internal heat integrated distillation columns (iHIDiCs) are further intensifications of vapor recompression principle. These columns combine the advantages of both direct vapor recompression and adiabatic operation and can have significantly lower energy demands than common vapor recompression distillation columns or heat pumps.

A systematic design hierarchy was proposed for iHIDiCs, including thermodynamic and hydraulic approaches. Starting from a conventional design, a full iHIDiC design can be achieved by performing basic design assumptions to conventional data. Temperature profiles are a key for heat integration, while hydraulic calculations are necessary to quantify the ability of a column design to place heat panels.

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