Manufacturing and Energy

Calculate Diffusion Coefficients in Liquids

Sat, 09 May 2009 00:02:42 -0700

The order of magnitude of diffusion coefficients in liquids is 10^-9 m2/s with the bulk of data in the range between 0.5 x 10^-9 m2/s and 5 x 10^-9 m2/s. Note that these data also hold for gases dissolved in liquids.

Equation of Chen and Othmer for gases is used for

� Its Simplicity
� Sufficiently Accurate
� Availability of Input Data

Correlation for liquids is that of Wilke and Chang (AIChE J. 1 (1955), 264):

Heat Capacity with Dissolved Solids

Fri, 08 May 2009 02:53:18 -0700

You are working on some design problem where a concentrated salt solution is under consideration and you are looking for its heat capacity. In such situation, will you use it to be equal to water Or it will be significantly different.

Yes, the answer is that it will be significantly different than water depending on its concentration. The deviation goes higher & higher if concentration increases.

The discussed equations are very useful for heat transfer calculations for slurry systems as well as solid handling systems.

So how to calculate it? Find out the easy way to calculate it.

Equal Percentage Valves - Opening Vs Flow

Thu, 23 Apr 2009 01:39:04 -0700

In case of equal percentage valves, the flow varies according to the following definition.

'Any % change in the opening from its current existing value changes the flow by same percentage of its current value at current opening.'

Means if current opening is say 10% & u change it to 15% than the change in opening from its current value (of 10%) is 50%, so the flow will also increase by 50% of its existing value at 10% opening. This means if flow was say 20% of the total range (Or capacity of the valve) at 10% opening it will become 30% (50% higher compared to 20%) of the total range.

So how to calculate it????

Pinch Technology - Some Basics

Sat, 21 Feb 2009 03:02:29 -0700

Most Industrial processes involve heat transfer from one process stream to another process stream (interchanging) or from a utility stream to a process stream. In the present energy crisis scenario, target in any industrial process is MER � Maximum Energy Recovery or Minimum Energy Requirements.

In the early days of pinch technology, the main emphasis was on heat exchanger network (HEN) design. Today pinch technology stretches far wider in the fields of overall process improvement and utility system design

Pinch Technology analyses process utilities (particularly energy and water) to find optimum way to use them, resulting in financial savings. It does this by making an inventory of all producers and consumers of these utilities and then systematically designing an optimal scheme of utility exchange between them. Energy and water re-use are at the heart of pinch technology.

With the application of pinch technology, both capital investment and operating cost can be reduced. Emissions can be minimized and throughput maximized.

Find out pump head without Curve

Tue, 30 Dec 2008 22:14:23 -0700

You are handling lot many centrifugal pumps & is always struggling for design data which may or may not be available specially in case of vintage units its very difficult to recollect them.

Even in newer plants if you do not have all procedures in place for documents handling you might face the same problem. What to do in such a case? Boss is not ready to listen any excuse.....You know that there is something wrong which can be improved and therefore you get a good recognition.......But

Here is the answer...

Types of Valves - Ball Valve

Mon, 29 Dec 2008 21:16:12 -0700

In the last article I discussed brief & important things about Globe Valve. Today I will discuss some basics of Ball Valve.

The Ball valves as name suggests is having a ball type spherical body. They are stop valves that use a ball to stop or start the flow of fluid. The ball performs the same function as the disk in the globe valve.

Vacuum Pumps - Dry Vs Liquid Ring

Wed, 24 Dec 2008 20:44:32 -0700

Vacuum is any system of reduced
pressure, relative to local (typically atmospheric) pressure. Achieved with a pump, vacuum systems are commonly used to

� Remove excess air and its constituents.
� Remove excess reactants or unwanted byproducts.
� Reduce the boiling point.
� Dry solute material.
� Create a pressure differential for initiating transport of material

Liquid-ring and dry pumps offer the most advantages for the chemical process industries (CPI). Both of these pump types have bearings sealed off from the pumping chamber and do not require any internal lubrication because the rotors do not contact the housing. Both, when employing a coolant system, prevent the coolant from contacting the process fluid and causing contamination, and both use mechanical shaft
seals for containment

Types of Valves - Globe

Tue, 23 Dec 2008 20:58:57 -0700

In the last article I discussed brief & important things about Gate Valve. Today I will discuss some basics of Globe Valve.

The Globe valves as name suggests is having a globe type spherical body which is divided in two parts by a baffle. Flow direction is steeply changed in this type of valve so the controlling of flow is better by the movement of restriction element.