Saturday, October 9, 2010
Chemical Engineering Digital Issue for Oct 2010...
Rare-earth metals for the future
Issues revolving around economics, workforce and technological innovation will be crucial as rare-earth metal production diversifies and demand for these critical technology metals grows
FAYF - MSMPR crystallization
This one-page reference guide describes examples of mixed-suspension, mixed-product removal crystallizers
Industrial Insulation Systems : Material Selection Factors
To provide the desired functions while beingexposed to harsh environments, insulation material should be carefully selected and specified to meet the design goals
Improving control valve performance
Control valves have a major impact on control-loop performance, so improvements in valve performance can have significant economic benefits. This article shows how poor control-valve performance can be identified and corrected to achieve these benefits
Crossover applications for the ASME-Bioprocessing Equipment Standard
The ASME-BPE Standard was created for the pharmaceutical industry, but can be very useful in the biofuel and chemical industries as well
Lessons in feedstock changes
Switching to renewable feedstocks can offer financial and environmental benefits, but can also compound challenges associated with processing solids
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Friday, October 8, 2010
FREE Hydrocarbon Processing for OCT 2010 is available now...
Click here to view the complete October issue
Articles from the October Issue in HP main focus on Advance control.
How to have a successful data reconciliation software implementation
Follow these guidelines to ensure success
Improve exploration, production and refining with 'add-at-will' wireless automation
After the technology was validated, a wireless infrastructure was installed blanketing 80% of a US refinery
Building and installing a reliable industrial Ethernet infrastructure
Here are six practical guidelines to consider
Increase your margin by 25%
Here's how to make sure that the planning LPs always match the plant
Advanced process control in the plant engineering and construction phases
Testing MVC performance using a dynamic model offers several benefits
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Atmospheric pressure change with altitude and this will have impacts to facilities design. Do not Under-estimate The Impact of Altitude Change. Sometime you may want to find altitude of specific location in particular you are conducting feasibility study and identifying plant location. This post will provide a quick way to find altitude of a plant using Google Map.
Following are some steps to find altitude of a specific location using Google Map :
Step 1 : Execute a "Find_Altitude.htm" by clicking here.
Step 2 : You may choose to Open the file using Internet Explorer or Save the file and execute later.
Step 3 : Google Map will shows map of Singapore island. You may zoom out the map by clicking "-" (in pull bar), left hand side of map
Step 4 : Zoom to the plant location you wish to find the altitude.
Step 5 : Double click the location. Altitude will be displaced in a box.
ExampleFind altitude of "Nature Reserve" and "Sentosa Island Beach" in Singapore island.
Step 1 : Execute a "Find_Altitude.htm" by clicking here.
Step 2 : Open the file using Internet Explorer. Google Map will shows map of Singapore island.
Step 3 : Double click the "Nature Reserve". The altitude of "Nature Reserve" in Singapore is approximately 60.64 m. See below image.
Step 4 : Double click the "Sentosa Island Beach". The altitude of "Sentosa Island Beach" in Singapore is approximately 0.0 m. See below image.
Shall take note that this is just for reference only.
Do you have better idea ?
Wednesday, October 6, 2010
Many LNG plants are built at the seaside to ease transportation, product loading and unloading. The atmospheric pressure with plant near seaside is 101325 Pa and all facilities are designed to the atmospheric pressure of 101325 Pa. However, if this plant is built in inland at high altitude, atmospheric pressure can seriously affect the design and operation of a LNG plant. Prior to discuss how the design and operation is impacted, lets step back to look at definition of pressure.
Operating pressure is commonly written as gauge pressure e.g. kPag, barg, etc in engineering whilst absolute pressure e.g kPaa, bara, etc. Absolute pressure equal to gauge pressure plus atmospheric pressure.
5 bar abs = 5 barg + 1.01325 bar = 6.01325 bara
The standard atmosphere pressure is pressure defined as being equal to 101,325 Pa or 101.325 kPa and normally refer to mean sea level (h=0 m). Atmospheric pressure is decreased with altitude (elevation from mean sea level or earth surface) with following relation.
Pb = Static pressure (Pa)
Tb = Standard temperature (K)
Lb = Standard temperature lapse rate -0.0065 (K/m) in ISA
h = Height above sea level (meters)
hb = Height at bottom of layer b (meters; e.g., h1 = 11,000 meters)
R = Universal gas constant for air: 8.31432 N.m /(mol.K)
g0 = Gravitational acceleration (9.80665 m/s2)
M = Molar mass of Earth's air (0.0289644 kg/mol)
Altitude = 0 – 11000m, Tb = 288.15 K, Lb = -0.0065 K/m, Pb = 101325 Pa
Altitude = 11000 – 20000m, Tb = 216.65 K, Lb = -1 x 10E-30 K/m, Pb = 22632.1 Pa
Altitude = 20000 – 32000m, Tb = 216.65 K, Lb = 0.001 K/m, Pb = 5474.89 Pa
By inclusion of specific parameters, for altitude = 0 – 11000m, atmospheric pressure is
At altitude of 500m above mean sea level, atmospheric pressure is approximately 95460.84 Pa.
At altitude of 1000m above mean sea level, atmospheric pressure is approximately 89874.57 Pa.
How altitude impacting LNG production rate ?
Let compare LNG production rate change with a plant built at seaside (h = 0) and another LNG plant built at a site with altitude of 1000m. For both plant, LNG store at same gauge pressure (e.g. 50 mbarg), same LNG rundown temperature (e.g. -163 degC), same LNG tank dimension with same in-leak heat (normally higher altitude is with lower ambient temperature, lower in-leak heat is expected. However, the impact is negligible).
LNG from Main Cryogenic Heat Exchanger (MCHE) outlet is set at 50 barg and negative 164.8 degC. A JT valve is letting down pressure to LNG storage tank operating pressure of 50 mbarg. MCHE outlet mass flow set at 50000 kg/h. LNG is pure Methane (C1). Assumed same in-leak heat of 300 kW.
Case : Seaside
Altitude, h = 0m
Atmospheric pressure = 101.325 kPa abs
LNG operating pressure = 50 mbarg = 5 + 101.325 kPa abs = 106.325 kPa abs
From simulation (see below image), BOG flow = 1374 kg/h,
LNG production rate = 48626 kg/h
Case : Inland
Altitude, h = 1000m
Atmospheric pressure = 101325 (1 - 2.25577E-05 x 1000)^5.25588 = 89.8746 kPa abs
LNG operating pressure = 50 mbarg = 5 + 89.8746 kPa abs = 94.8746 kPa abs
From simulation (see below image), BOG flow = 1863 kg/h,
LNG production rate = 48137 kg/h
Same facilities and operating condition, the LNG production in Inland (at 1000m) reduced by 1%.
How altitude impacting Air Compressor / Blower power requirement ?
Air compressor at seaside is sucking air at atmospheric pressure of 101.325 kPa abs. If this air compressor is located at altitude of 1000m, air compressor is sucking air at atmospheric pressure of 89.8746 kPa abs. With same discharge pressure, higher head is expected at high altitude and higher power is required. Normally the head is rather large for air compressor, therefore the additional power may not be so significant. However, it could be significant for an air blower sent air to process with fix pressure. One shall remember, it may have no significant impact to an air blower sucking air from atmosphere and discharging air to atmosphere again.
Atmospheric pressure change with altitude and this will have impacts to facilities design. Do not under-estimate this impact.