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THERMODYNAMIC PROPERTIES OF FLUIDS

Hello dear readers, in the previous section I tried a few issues that need to be clear on the basic engineering design, particularly the engineering process, such as vapor pressure or saturation pressure .

http://www.proptermodinamicas.blogspot.com/ (to see article above)
http://procesostermodinamicosaplicacion.blogspot.com/ (to see first article)

This time, try to exemplify why it is important to understand these concepts, as is almost customary use some of the engineering design projects I've developed for oil and gas industry.

FIRST APPLICATION (CAVITATION PUMPING EQUIPMENT)

Issue:

lubricating oil supply to turbo-machinery equipment plant was done through drums of 200 liters and 1000 liters isotanks, which were piled causing a problem and limited access areas. On the other hand, supplying the lubricating oil in these conditions required a series of movements important and involved serious risks of accidents for the operation and maintenance personnel, there is also the possibility of oil spills in the handling and manual decanting of lubricating oil.

Solution:

system was implemented automated storage and distribution for turbomachinery lubricating oil of the plant and thereby reduce risks to staff, optimizing space for the management of oil drums, discarded in this way possibility of oil spills causing a negative environmental impact.

Development:

This storage system mainly consists of the following teams:

a) A storage tank was located on the first level of the plant.
b) Two pumps (one in operation and a relay).
c) A filtration system was located at the discharge of the pumps.

following shows schematically the installation of the storage and distribution system.

Figure 1: Schematic diagram of system storage and distribution of oil (Turbine 11).

I. Synthesis process:

pumps lube oil distribution are double diaphragm. The pumping system with 2 pumps (One in service and one backup), BA-BA-101A and 101R, respectively, to distribute the oil to a depth of approximately 20 meters. The arrangement of pipes in the suction and discharge of the pumps allow the option of normal use for distribution or use oil for the transfer of lubricating oil to the storage tank from 200 liter drums. or 1000 liters.

lubricating oil supply that feeds the turbo-machinery will be done through the distribution head, before which the oil passed through a duplex strainer basket FL-1001 to remove impurities from your system.

II. General concepts

CAVITATION

are known phenomenon of cavitation occurs when a point of a liquid stream, the pressure becomes less than the vapor pressure corresponding to the temperature which is the liquid the decrease in pressure causes the liquid to boil at a temperature well below 100 º c or begin to vaporize. In some cases depending on traffic conditions will form a steam piston, which sometimes come to completely block the flow: in others, small cavities are occupied by vapor bubbles, which carries the current and to reach places where there is greater pressure, collapse, accompanying this collapse with sudden compression stress intensity.

NPSH (Net Loading P osita of Suction)

By definition, the NPSH is the total height of cargo to the pump inlet, measured relative to the plane of references, plus the height corresponding to atmospheric pressure and the height decreased due to the tension of the liquid.

should bear in mind two concepts:

NPSH (Available)

total absolute pressure in the ear of the impeller and the suction end result specifies the conditions of the installation. Depending on the installation is independent of the type of pump.

NPSHd knowledge of the installer is essential for the proper choice of the pump and prevent possible failures.

NPSH (Required)

minimum absolute pressure in the ear of the driver that ensures a healthy flow inside the pump. Is a central characteristic de cada tipo de bomba, variable según el modelo y tamaño y condiciones de servicio, por tanto es un dato que facilitan los fabricantes de los equipos de bombeo.

Para un funcionamiento correcto de una instalación se verificará siempre que:

NPSHD ≥ NPSHR

En esta ocasión solamente mostraré la metodología utilizada para el cálculo la carga positiva neta de succión disponible (NPSHD), ya que el dimensionamiento total de equipos de bombeo será tratado en otro capitulo.

III. Propiedades del fluido:

Las principales propiedades de los aceites lubricantes (turbina 11) bombeados se muestran a continuación:

FLUID

IV. Operating conditions

V. Design criteria.

The first step in our methodology is to establish the design criteria.

design criteria used for this system are based on national and international standards of design and installation of piping systems, which show the following:

The pressure drop per 100 ft of pipe (suction pumps supercooled liquid)
ΔP100 = 0.05 to 0.25 psi (lb/in2)

The recommended speed (suction of supercooled liquid pumps):
V = 1 to 5 ft / sec.

Fig. 2. Schematic diagram of the variables in a typical pumping system.

VI. Formulas

1 .- Diameter of suction: This will give an approximate diameter required but is not definitive because it must verify that it meets the criteria of the pressure drop

2 - Reynolds Number

3 .- Friction factor: On this occasion we will use the following equation (Fanning), but this formula has limitations that will treated in the chapter on design of a phase line.

4 - Pressure Drop per 100 ft pipe

5 .- Equivalent length (LE)

The following table gives the equivalent lengths of pipe for various accessories:

Fig. 3. Table of equivalent length of valves and fittings in feet (API-RP-14E).

Click on this link to download fig.3 http://rapidshare.com/files/208835031/TABLA.jpg.html

6 .- frictional pressure drop:
7 .- Load net suction available (NPSHd):

Where:

PS = Pres . abs e / suction cup (like our drum is open to the atmosphere will be equal to 14 . 7 PSIA = 33 . 93 ft of H2O) h = Height
liq. (With respect to the axis of the pump) = 1m + liquid height = 1.90 m = 6.23 ft
ΔPF = frictional pressure drop (ft)-is calculated
ΔP100 = pressure drop per 100 ft-(PSIG)
HV = Vapor pressure of liquid = 0.0155 Kg / cm ² = 0.22 PSIA = 0,508 ft of H2O
Re = Reynolds Number (dimensionless)
ρ = liquid density (lb/ft3)
Q = volumetric flow rate (GPM)
Di = Inner diameter (in)
μ = fluid viscosity (cp)
V = Velocity of fluid (ft / s)
For our particular case, the suction head as shown in Figure 1 The oil tank is above the pump shaft, so our hours will be positive (+).

VII. Calculations

1 .-

As use the next higher diameter:

Dn = 2 in
Di = 1,939

2 .- 3 .-
4 .-

How can we check our selected diameter (2 in), according the required flow (20 GPM), does not meet the criterion of pressure drop per 100 ft, although in speed if.

At this point one must consider the criteria of speed vs. pressure drop, usually suction pumps the most important criterion to meet is ΔP100, so proceed to select a larger diameter.

Dn = 3 in
Di = 3,068

recalculated are:


Re = 335,493 F = 0.1058 = 0,103 PSI
ΔP100

As you can see with a diameter of 3 in. in diameter, we have that if we comply with the pressure drop criteria set out in section IV. 5 .-

accessories including suction of these pumps is shown in the following table:

6 .- 7 .-

The figure of 39,543 ft of water can be expressed in ft of fluid we are dealing with (Diesel in our case), for it will divide the feet of water between the specific gravity (relative density) of Diesel

Sp.gr (Diesel) = 0.874

Therefore NPSHd = 45.24 ft diesel

VIII. Interpretation:

calculated according to NPSHd NPSHR should check provided by the manufacturer, if the NPSH available is greater than the latter should be increased, otherwise it will form the phenomenon of cavitation in the pump.

IX. Application of thermodynamic properties:

The application in this example is the vapor pressure or saturation pressure, because if was not given due importance, and not taken into account, we may fall into the error that suction pressure is less than the vapor pressure, and thus be formed cavitation.

second application (CONTROL VALVE)

control valves are exposed to all kinds of influences in process control. This requires the existence of a large variety of designs depending on series and of what the specific problem to be solved in each particular application. So if we add to this variation may experience both physical and chemical parameters of the fluid, or all those parameters that can affect the process itself requires us to use a special calculation technique when performing the choice of control valve.

The phenomenon of cavitation occurs when a liquid flowing through a pipeline will reduce the flow through a control valve, it speeds up considerably (the principle of conservation of mass). This increase in speed leads to pressure loss (principle of conservation of energy). If this low pressure drop below the saturation pressure of the fluid, it produces bubbles of steam seeking greater pressure zones which collapse abruptly. These areas are often the control valve itself and immediately afterwards, since the pressure is recovered by slowing the rate to its initial value.

Fig. 4. Graph of pressure and velocity relative to the saturation pressure.

In this process, vapor bubbles form a static cavitation zone which varies in length depending on differential pressure. The vapor bubble implosions produce what is known as micro-jets (small portions of fluid propelled at high speed and short life, maximum number of milliseconds), them when they hit a solid material, such as a valve body, damage and wear. They may even eventually get "to eat" the body of the valve, especially in control valves that redirect the fluid. However, although they develop a control valve ingenious design, it would be possible for procedural reasons, to ensure that cavitation would be free of all conditions (for example Xf> Z)

Fig.5. Areas of cavitation in a control valve.

VALUE Z

Z value is what determines and lets us know when a fluid passing through a control valve cavitate. Its value is very important and depends mainly on 3 factors:

a) The valve design

b) vs. K value that we use (if it is reduced or not)

c) Position actual opening or closing the valve

The ranges z value ranging from 0 to 1, being much more favorable terms to avoid cavitation closest to 1. The z value is obtained through laboratory testing and must facilitate the manufacturer of any type of control valve. We will develop an example to clarify everything described above:

Example:

Data:

Fluid: Water at 20 º C

inlet pressure to the valve: 145 PSIA

Outlet pressure: 29 PSIA.

fluid pressure vaporization: 0.3452 PSIA @ 20 ° C

Z value of 65% valve opening: 0.6 (Data supplied by it manufacturer)

First, we find the value Xf

Xf If the value is greater than the Z value, the valve will cavitate, as much as 0.802> 0.6 in our case there CAVITATION, and the greater the difference between value and value Xf Z Most get

cavitation Once developed the example above, we see the importance of awareness of the value Z of a control valve for a process to determine if the control valve to cavitate and magnitude.

far we have come to the application of thermodynamic properties, I hope you have been to your liking and give them a broader approach to these properties within the oil and gas industry. As you can tell clearly having this knowledge allows us to design effective and safe.

I hope in my next post, where interesting topics try Bá Engineering and music of detail ( Process, Piping usage coming from designers as , Instrumentació n and Process Control, Industrial Safety ) with a approach to the industry with more boom in Mexico, "the oil industry .

Until next time.

Congradulation Speech

The "paganism" of the Catholic Church

By Greg Oatis

Source: http://www.apologeticacatolica.org/

Some people argue that the Catholic Church was not founded by Jesus Christ, being more of a pagan cult with ties that bind ancient Babylon. This idea reached widely disseminated through a book, "The Two Babylons" published in Britain by Alexander Hislop in 1858 which aimed to establish a relationship between Catholic teachings and practices of the religion practiced in that mystery Babylon. However, the methodology used by the author of the book, a Protestant minister with no serious academic training, has been rejected and denounced as false from the standpoint of sound and historical.

Revelation 23, 1-4 - Then came one of the seven angels which had the seven bowls came and spoke to me: "Come, I'll show trial of the notorious prostitute who sits on many waters, with whoring her the kings of the earth and the inhabitants of the earth were intoxicated with the wine of her prostitution. " I moved in spirit to the desert. I saw a woman sitting on a scarlet beast covered with blasphemous titles, the beast with seven heads and ten horns. The woman was arrayed in purple and scarlet, shining with gold, precious stones and pearls, holding in her hand a golden cup full of abominations and filthiness of her prostitution and her forehead was a name written, MYSTERY, "The Great Babylon, the mother of harlots and abominations of the earth. " And I saw the woman drunk with the blood of the saints and the blood of the martyrs of Jesus. And I was greatly amazed to see her, but the angel said, "Why are you surprised? I will explain the mystery of the woman and the beast she rides, which has seven heads and ten horns. "

This passage is often used to" prove "that the Catholic Church is the whore of Babylon" to San Juan describes in his vision. Such an interpretation is not only wrong but it is impossible to reconcile with the story. Obviously, for anyone seriously studying the scriptures, that St. John is referring to Rome as "Babylon the Great" as Rome and Babylon were the only two powers of this world which God allowed overthrew Jerusalem, leading to exile him away to his village. Both Jewish and Christian writings have been compared to Rome with the ancient Babylon, as both subjugated Israel, destroyed the Holy Temple and Jerusalem devastated.

A well-known promoter of the interpretations of Hislop, Ralph Woodrow, following the same path, even wrote another book called "Babylon, Mystery Religion." Woodrow years later had to repudiate the method he had learned from Hislop when scholars of his own Protestant group he noted the serious deficiencies and lack of scholarship. In 1997, Woodrow published a retraction, "The Babylonian Connection?" in which exposed the essentially false starting points of the original theories of the Scottish religious fundamentalist. To illustrate the kind of faulty logic in play, Woodrow using the very methods Hislop to "prove" a preposterous theory: that a certain chain of fast food has its roots in Babylon. Quote:

- "golden arches" are known worldwide as the identifying symbol of McDonald's. However, we note that the arch was commonly used by the ancient Babylonians in their doors and palaces. In fact, in paintings by the Babylonians, we see that their kings are represented in arch-shaped frames! We also know that Nebuchadnezzar, the Babylonian king, ordered his subjects to worship a golden image (Daniel 3, 5-10). And Babylon was known in the world old as "the golden city." Finally, note that the first letter to McDonald's, the M is the thirteenth letter of the alphabet (English), a number recognized as having a mystical power to bring bad luck. Can this be mere coincidence? Even, why the M points in addition to McDonald's? Clearly to Molech, the pagan god of fire worship in Babylon. What is used to heat food in a McDonald's modern? Electricity, which many associate with a controlled fire! Therefore, who can doubt that the restaurant chain McDonald's, known for its golden arches, is actually a mystery cult related with the fire god worshiped by the ancient Babylonian royalty?

As ridiculous as this absurd way of reasoning may seem, just know that the chain of McDonald's was not created by a king of Babylon, but by an American businessman named Ray Kroc in 1950-this is exactly the same technique Hislop reasoning used to slander the Church. In his essay "Anti-Catholicism, the Catholic apologist Dave Armstrong errors Hislop said:" The method [Hislop] incurs two well-known logical fallacies: the fallacy of "origin", which attacks the source of a idea rather than the idea itself and the fallacy of "non sequitur" in which a similar number "Proof" that a practice from another past practice ... "For clarification let's say a logical fallacy is a statement presented as a true statement, but it is only in appearance. The logical fallacies are commonly used to justify arguments or positions that are not justifiable using reason. They tend to mask deception, misrepresentation, or fraud. Knowing how to recognize logical fallacies is helpful not to be deceived. The Latin term "non sequitur" means literally "not followed". If we are analyzing the similarity of an ancient Catholic practice Babylonian practice does not mean that the first comes from the second. Woodrow

also notes that, if used Hislop's own arguments, you could "prove" that the Bible itself is pagan. Shows many elements in the Bible that can be related to pre-existing pagan religions, such as prostrate on the ground, praying, raising hands, a mountain with this in her divinity, law engraved in stone, Elijah cart horses of fire. All this and much more biblical phenomenology, can also be found in paganism.

Therefore, if we Hislop fallacious logic, we would be forced to conclude that the faith taught in Scripture is actually a pagan religion. Since we know that's absurd, we must necessarily conclude that the technique of Hislop is fundamentally flawed.

1 Corinthians 9, 20-22 - To the Jews I have become a Jew to win Jews, with those under the law, and who is under the Act, even without being so, to win those who are under it. With those who are without law, as those without law to win those who are without law, not being without law toward God but under the law of Christ. I became weak with the weak to win the weak. I've done everything to everyone at all costs to save some.

Rather than condemn any practice of the Gentiles as pagan, the Catholic Church has always sought inculturated. Ie, has respected the good that may be in other religions and cultures to relate to the truth in the Father, Son and Holy Spirit.
Acts 10:9-16 - What God has cleansed, you must not call profane.

Jesus came to bring salvation to all mankind. Included those who were seen by Jews as impure, and not just a chosen few. In other words, the love of God is not just for those who already practice the Christian faith. He loves all men, which created in His image and likeness. Acts 17:16-34

- Athens, I perceive that you are, by all accounts, the most respectful of divinity. And watch for after your worship, I found an altar on which was engraved the inscription: "To an unknown god." What therefore you worship as unknown, this I proclaim to you.

St. Paul preached a fiery condemnation of the Greeks for their pagan worship. Rather, he used their beliefs as a tool through which to reveal the full truth is in Christianity. The Catholic Church has always acted that way. Note also that in verse 28 is a reference to St. Paul to two pagan poets, Epimenides ("In Him we live and move and have our being ") and Aratos (" For we are also his lineage "). Does this mean that Paul was preaching a pagan religion? Using the system to test things Hislop, would come to this ridiculous conclusion. However, it is clear from the context that Paul is using proper technique to debate: empathy. Just for your message using terms that make sense for your audience.

Acts 22, 25 - When you were stretched with thongs, Paul said to the centurion who was there: "I is permissible to whip a Roman citizen without having been tried?"

In Acts 22, San Pablo 25-28 We see repeatedly stating his Roman citizenship-that is, citizenship in a pagan empire in its disputes with the temple authorities. Obviously he saw no such thing as a desecration.

Sometimes, certain fundamentalists seem more concerned with preserving the pristine nature of an idealized Christianity, while retaining a kind of amber theological than following the example of St. Paul using all the cunning, art and own brain in effort to save souls whom God loves. Paul was less busy in maintaining the purity of their traditional religious practices, such as circumcision or the Jewish dietary laws, which in the search for the transmission of faith, which is dedicated to courage and when he found necessary, used unconventional ways. Therefore there is no reason to fear when our faith is attacked, debated, even in the arena of the world of ideas. The essential truth of the Gospel is their protection