Dehradun/New Delhi: The National Disaster Management Authority
on Sunday said that the death toll in Uttarakhand floods might cross
10,000. "Like the Speaker said, it could be more than 10,000. The exact
number, however, cannot be known immediately," NDMA Vice Chairman
Shashidhar Reddy said. He added that as many 1500 people are still
stranded in the hill state.
Uttarakhand Assembly Speaker Govind Singh Kunjwal had said on
Saturday that he fears that more than 10,000 people could have been
killed in the calamity. "When I returned from Garhwal, I said the death
toll could be between 5000 and 10,000. But now I think the death toll
could be more than 10,000," he said.
While there has been no clarity yet on how many people lost their
lives in Uttarakhand floods, conflicting figures are emerging about the
number of missing people also. Uttarakhand Chief Minister Vijay
Bahuguna on Sunday claimed that as many as 3000 people could be missing
in the floods but the NDMA pegged the figure at 1800.
"After compiling the data, I've been informed that around 3000 people
are missing. If a person is not found in 30 days, the state government
will give compensation to the family. About 1335 villages still have no
connectivity or aid," Bahuguna said.
The Chief Minister also said a team of 200 people has been
formed, including doctors, which will take DNA samples of the dead
bodies found. Bahuguna added that out of 4200 villages, connectivity has
been restored in 2865 villages. Relief material is being provided
through choppers to rest of the 1335 villages, he said. He further
clarified that there are no report of an epidemic anywhere.
The NDMA Vice Chairman said that among the 1500 people who are
stranded at various parts of Uttarakhand, there are many locals also.
"According to the figures 1,07,670 people have been rescued so far. The
road between Badrinath and Rambada has been repaired while a stretch in
Lambagad is being repaired," he added. The road from Joshimath to
Govindghat has now been restored and pilgrims are being evacuated on
foot. But there is confusion over the number of pilgrims on ground.
The rescue operations in Uttarakhand are set to wind by Monday
and the focus of the security forces has shifted on saving 2000 people,
who are still stuck in the higher reaches. However, evacuated pilgrims
claim that far greater number of pilgrims are stranded than what the
officials have been stating.
According to the Indian Air Force, 842 people were rescued from
Badrinath on Saturday even as air sorties were stalled briefly due to
bad weather and many pilgrims in Badrinath were evacuated on foot
through a newly constructed foot track in Govindghat valley. Harsil was
fully evacuated on Saturday.
Meanwhile, the India Meteorological Department (IMD) has claimed
it issued several advisories to the Uttarakhand government, warning it
about the massive landslides and rains that have ravaged the state,
killed hundreds of people and swept away houses.
"We had issued warnings on June 14 and since then we have been
regularly issuing advisories. The warnings were even published in
newspapers and a press release was also issued," Uttarakhand MeT
department Director Anand Sharma said.
A Congress leader on Sunday claimed there was "poor coordination"
among the rescue teams in Uttarakhand. "There was poor coordination in
the rescue operations. Authorities in one area did not know the progress
of operations in other areas. I kept asking the state authorities
including the Chief Minister for immediate air support. Speedy action by
the state government would have been effective," Pradeep Tamta said.
Dedicated Team spirit and thanks to Greenko group CEO and MD Shri Chalamalasetty Sir and Shri Mahesh Koli SIr, AM Green management Shri Gautam Reddy, Shri GVS ANAND, Shri K.Pradeep Shri VIJAY KUMAR (Site Incharge), Shri G.B.Rao, Shri PVSN Raju, Dr. V. Sunny John, Shri V. Parmekar ,Smt .Vani Tulsi,Shri B. B.K Uma Maheswar Rao, Shri T. Govind Babu, Shri P. Rajachand, Shri B.V Rao, Shri. LVV RAO ,Shri P.Srinivaslu Promotion- EHSQL-by Dr. A.N.GIRI- 28.1 Lakhs Viewed Thanks to NFCL.
Sunday, 30 June 2013
Ammonia
Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
Ammonia
CAS number: 7664-41-7NIOSH REL: 25 ppm (18 mg/m3) TWA, 35 ppm (27 mg/m3) STEL
Current OSHA PEL: 50 ppm (35 mg/m3) TWA
1989 OSHA PEL: 35 ppm (27 mg/m3) STEL
1993-1994 ACGIH TLV: 25 ppm (17 mg/m3) TWA, 35 ppm (24 mg/m3) STEL
Description of substance: Colorless gas with a pungent, suffocating odor.
LEL: 15% (10% LEL, 15,000 ppm)
Original (SCP) IDLH: 500 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by AIHA [1971] that 300 to 500 ppm for 30 to 60 minutes have been reported as a maximum short exposure tolerance [Henderson and Haggard 1943]. AIHA [1971] also reported that 5,000 to 10,000 ppm are reported to be fatal [Mulder and Van der Zahm 1967] and exposures for 30 minutes to 2,500 to 6,000 ppm are considered dangerous to life [Smyth 1956].
Existing short-term exposure:
1988 American Industrial Hygiene Association (AIHA) Emergency Response Planning Guidelines (ERPGs)
- ERPG-1: 25 ppm
- ERPG-2: 200 ppm
- ERPG-3: 1,000 ppm
- 1-hour EEGL: 100 ppm
- 24-hour EEGL: 100 ppm
- Continuous exposure (60 days): 25 ppm
- 1 hour: 400 ppm
Lethal concentration data:
Species | Reference | LC50(ppm) | LCLo(ppm) | Time | Adjusted 0.5-hr LC (CF) | Derived Value |
---|---|---|---|---|---|---|
Rat | Alarie 1981 | 40,300 | ----- | 10 min | 23,374 ppm (0.58) | 2,337 ppm |
Rat | Alarie 1981 | 28,595 | ----- | 20 min | 23,448 ppm (0.82) | 2,335 ppm |
Rat | Alarie 1981 | 20,300 | ----- | 40 min | 23,345 ppm (1.15) | 2,335 ppm |
Rat | Alarie 1981 | 11,590 | ----- | 1 hr | 16,342 ppm (1.41) | 1,634 ppm |
Rat | Back et al. 1972 | 7,338 | ----- | 1 hr | 10,347 ppm (1.41) | 1,035 ppm |
Mouse | Back et al. 1972 | 4,837 | ----- | 1 hr | 6,820 ppm (1.41) | 682 ppm |
Rabbit | Boyd et al. 1944 | 9,859 | ----- | 1 hr | 13,901 ppm (1.41) | 1,309 ppm |
Cat | Boyd et al. 1944 | 9,859 | ----- | 1 hr | 13,901 ppm (1.41) | 1,309 ppm |
Rat | Deichmann and Gerarde 1969 | 2,000 | ----- | 4 hr | 5,660 ppm (2.83) | 566 ppm |
Mammal | Flury 1928 | ----- | 5,000 | 5 min | 2,050 ppm (0.41) | 205 ppm |
Mouse | Kapeghian et al. 1982 | 4,230 | ----- | 1 hr | 5,964 ppm (1.41) | 596 ppm |
Human | Tab Biol Per 1933 | ----- | 5,000 | 5 min | 2,050 ppm (0.41) | 205 ppm |
Other human data: The maximum short exposure tolerance has been reported as being 300 to 500 ppm for 0.5 to 1 hour [Henderson and Haggard 1943]. A change in respiration rate and moderate to severe irritation has been reported in 7 subjects exposed to 500 ppm for 30 minutes [Silverman et al. 1946].
Revised IDLH: 300 ppm Basis for revised IDLH: The revised IDLH for ammonia is 300 ppm based on acute inhalation toxicity data in humans [Henderson and Haggard 1943; Silverman et al. 1946]. |
- AIHA [1971]. Anhydrous ammonia. In: Hygienic guide series. Am Ind Hyg Assoc J 32:139-142.
- Alarie Y [1981]. Dose-response analysis in animal studies: prediction of human responses. Environ Health Perspect 42:9-13.
- Appelman LM, ten Barge WF, Reuzel PGJ [1982]. Acute inhalation toxicity study of ammonia in rats with variable exposure periods. Am Ind Hyg Assoc J 43:662-665.
- Back KC, Thomas AA, MacEwen JD [1972]. Reclassification of materials listed as transportation health hazards. Wright-Patterson Air Force Base, OH: 6570th Aerospace Medical Research Laboratory, Report No. TSA-20-72-3, pp. A-172 to A-173.
- Boyd EM, MacLachlan ML, Perry WF [1944]. Experimental ammonia gas poisoning in rabbits and cats. J Ind Hyg Toxicol 26:29-34.
- Deichmann WB, Gerarde HW [1969]. Trifluoroacetic acid (3FA). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., p. 607.
- Flury F [1928]. Moderne gewerbliche vergiftungen in pharmakologisch-toxikologischer hinsicht (Pharmacological-toxicological aspects of intoxicants in modern industry). Arch Exp Pathol Pharmakol 138:65-82 (translated).
- Henderson Y, Haggard HW [1943]. Noxious gases. 2nd ed. New York, NY: Reinhold Publishing Corporation, p. 126.
- Kapeghian JC, Jones AB, Mincer HH, Verlangieri AJ, Waters IW [1982]. The toxicity of ammonia gas in the mouse. Fed Proc 41:1568 [Abstract #7586].
- Mulder JS, Van der Zahm HO [1967]. Fatal case of ammonium poisoning. Tydschrift Voor Sociale Geneeskunde (Amsterdam) 45:458-460 (translated).
- NRC [1987]. Emergency and continuous exposure guidance levels for selected airborne contaminants. Vol. 7. Ammonia, hydrogen chloride, lithium bromide, and toluene. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 7-15.
- Silverman L, Whittenberger JL, Muller J [1946]. Physiological response of man to ammonia in low concentrations. J Ind Hyg Toxicol 31:74-78.
- Smyth HF Jr [1956]. Improved communication: hygienic standards for daily inhalation. Am Ind Hyg Assoc Q 17(2):129-185.
- Tab Biol Per [1933]; 3:231-296 (in German).
- ten Berge WF, Zwart A, Appelman LM [1986]. Concentration-time mortality response relationship of irritant and systematically acting vapours and gases. J Haz Mat 13:301-309.
- U.S. Bureau of Ships [1962]. Submarine atmosphere habitability data book. AVSHIPS 250-649-1. Rev. 1. Washington, DC: U.S. Department of the Navy, U.S. Bureau of Ships, p. 629.
Measuring Air Humidity
Measuring relative air humidity with dry and wet bulb temperatures
Sponsored Links
Air humidity can be estimated by measuring
Dry Bulb Temperature - Tdb - can be measured with a simple thermometer as shown above.
Wet Bulb Temperature - Twb - can be measured with a standard thermometer with some wet clothing, cotton or similar, around the bulb. Note that a continuously air flow is important to evaporate water from the wet clothing and achieve a correct wet bulb temperature.
Sufficient air movement can be achieved with a sling thermometer or similar.
Relative humidity can be estimated from the tables below or alternatively from a psyhrometric or Mollier diagram.
- the dry bulb temperature
- the wet bulb temperature
Wet Bulb Temperature - Twb - can be measured with a standard thermometer with some wet clothing, cotton or similar, around the bulb. Note that a continuously air flow is important to evaporate water from the wet clothing and achieve a correct wet bulb temperature.
Sufficient air movement can be achieved with a sling thermometer or similar.
Relative humidity can be estimated from the tables below or alternatively from a psyhrometric or Mollier diagram.
Temperature in Fahrenheit
Relative Humidity - RH (%) | ||||||||
Difference Between Dry Bulb and Wet Bulb Temperatures Tdb - Twb (oF) |
Dry Bulb Temperature - Tdb (oF) | |||||||
60 | 64 | 68 | 72 | 76 | 80 | 84 | 88 | |
1 | 94 | 95 | 95 | 95 | 96 | 96 | 96 | 96 |
2 | 90 | 90 | 90 | 91 | 91 | 92 | 92 | 92 |
3 | 84 | 85 | 85 | 86 | 87 | 88 | 88 | 89 |
4 | 78 | 80 | 81 | 82 | 83 | 84 | 84 | 85 |
5 | 73 | 75 | 76 | 78 | 79 | 80 | 80 | 81 |
6 | 68 | 70 | 72 | 73 | 75 | 76 | 77 | 78 |
7 | 63 | 66 | 67 | 69 | 71 | 72 | 73 | 74 |
8 | 58 | 61 | 63 | 65 | 67 | 68 | 70 | 71 |
9 | 54 | 57 | 59 | 61 | 63 | 65 | 66 | 68 |
10 | 49 | 52 | 55 | 57 | 59 | 61 | 63 | 64 |
Temperature in Celsius
Relative Humidity - RH (%) | ||||||||
Difference Between Dry Bulb and Wet Bulb Temperatures Tdb - Twb (oC) |
Dry Bulb Temperature - Tdb (oC) | |||||||
15 | 18 | 20 | 22 | 25 | 27 | 30 | 33 | |
1 | 90 | 91 | 91 | 92 | 92 | 92 | 93 | 93 |
2 | 80 | 82 | 83 | 84 | 85 | 85 | 86 | 87 |
3 | 71 | 73 | 75 | 76 | 77 | 78 | 79 | 80 |
4 | 62 | 65 | 67 | 68 | 70 | 71 | 73 | 74 |
5 | 53 | 57 | 59 | 61 | 64 | 65 | 67 | 69 |
6 | 44 | 49 | 52 | 54 | 57 | 59 | 61 | 63 |
7 | 36 | 42 | 45 | 47 | 51 | 53 | 55 | 58 |
8 | 28 | 34 | 38 | 41 | 45 | 47 | 50 | 53 |
9 | 21 | 27 | 31 | 34 | 39 | 41 | 45 | 48 |
10 | 13 | 20 | 25 | 28 | 33 | 36 | 40 | 43 |
Refrigerants - Environment Properties
Refrigerants - Ozone Depletion (ODP) and Global Warming Potential (GWP)
Common refrigerants and Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) are indicated below.
* CO2 is the GWP reference
- Ozone Depletion Potential (ODP) of a chemical compound is the relative amount of degradation it can cause to the ozone layer
- Global Warming Potential (GWP) is a measure of how much a given mass of a gas contributes to global warming. GWP is a relative scale which compares the amount of heat trapped by greenhouse gas to the amount of heat trapped in the same mass of Carbon Dioxide. The GWP of Carbon Dioxide is by definition 1. Be aware that GWPs are highly controversial.
Refrigerant | Ozone Depletion Potential (ODP) |
Global Warming Potential (GWP) |
R-11 Trichlorofluoromethane | 1.0 | 4000 |
R-12 Dichlorodifluoromethane | 1.0 | 2400 |
R-13 B1 Bromotrifluoromethane | 10 | |
R-22 Chlorodifluoromethane | 0.05 | 1700 |
R-32 Difluoromethane | 0 | 650 |
R-113 Trichlorotrifluoroethane | 0.8 | 4800 |
R-114 Dichlorotetrafluoroethane | 1.0 | 3.9 |
R-123 Dichlorotrifluoroethane | 0.02 | 0.02 |
R-124 Chlorotetrafluoroethane | 0.02 | 620 |
R-125 Pentafluoroethane | 0 | 3400 |
R-134a Tetrafluoroethane | 0 | 1300 |
R-143a Trifluoroethane | 0 | 4300 |
R-152a Difluoroethane | 0 | 120 |
R-245a Pentafluoropropane | 0 | |
R-401A (53% R-22, 34% R-124, 13% R-152a) | 0.37 | 1100 |
R-401B (61% R-22, 28% R-124, 11% R-152a) | 0.04 | 1200 |
R-402A (38% R-22, 60% R-125, 2% R-290) | 0.02 | 2600 |
R-404A (44% R-125, 52% R-143a, R-134a) | 0 | 3300 |
R-407A (20% R-32, 40% R-125, 40% R-134a) | 0 | 2000 |
R-407C (23% R-32, 25% R-125, 52% R-134a) | 0 | 1600 |
R-502 (48.8% R-22, 51.2% R-115) | 0.283 | 4.1 |
R-507 (45% R-125, 55% R-143) | 0 | 3300 |
R-717 Ammonia - NH3 | 0 | 0 |
R-718 Water - H20 | 0 | |
R-729 Air | 0 | |
R-744 Carbon Dioxide - CO2 | 1* |
Water Delivery Flow Velocities
Water Delivery Flow Velocities
Required flow velocities in water transport systems - on the delivery side of the pump
As a rule of thumb the following velocities can be used in design of piping and pumping systems for water:Pipe Dimension | Water | ||
---|---|---|---|
inches | mm | m/s | ft/s |
1 | 25 | 1 | 3.5 |
2 | 50 | 1.1 | 3.6 |
3 | 75 | 1.15 | 3.8 |
4 | 100 | 1.25 | 4 |
6 | 150 | 1.5 | 4.7 |
8 | 200 | 1.75 | 5.5 |
10 | 250 | 2 | 6.5 |
12 | 300 | 2.65 | 8.5 |
Pipes and Tubes - Recommended Insulation Thickness
To avoid heat loss and reduced efficiency pipe work in heating
systems should always be insulated. Very hot systems, like hot water and
steam
systems should also be insulated to avoid potential personal
injuries.
The table below indicates recommended insulation thickness.
* based on insulation with thermal resistivity in the range 4 - 4.6 ft2
hr oF/ Btu in
The table below indicates recommended insulation thickness.
Recommended minimum Thickness of Insulation (inches)* | ||||
Nominal Pipe Size NPS (inches) |
Temperature Range (oC) | |||
50 - 90 | 90 - 120 | 120 - 150 | 150 - 230 | |
Temperature Range (oF) | ||||
120 - 200 | 201 - 250 | 251 - 305 | 306 - 450 | |
Hot Water | Low Pressure Steam | Medium Pressure Steam | High Pressure Steam | |
< 1" | 1.0 | 1.5 | 2.0 | 2.5 |
1 1/4" - 2" | 1.0 | 1.5 | 2.5 | 2.5 |
2 1/2" - 4" | 1.5 | 2.0 | 2.5 | 3.0 |
5" - 6" | 1.5 | 2.0 | 3.0 | 3.5 |
> 8" | 1.5 | 2.0 | 3.0 | 3.5 |
Ideal Gas Law
Ideal Gas Law
In perfect or ideal gas the change in density is directly related to the change of temperature and pressure as expressed by the Ideal Gas Law
In perfect or ideal gas the change in density is directly
related to the change of temperature and pressure as expressed by the
Ideal Gas Law.
Equation (1) can also be modified to
The air density can be calculated with a transformation of the ideal gas law (2) to:
The True Gas Law, or the Non-Ideal Gas Law, becomes:
The Ideal Gas Law and the Individual Gas Constant - R
The Ideal Gas Law relates pressure, temperature, and volume of an ideal or perfect gas. The Ideal Gas Law can be expressed with the Individual Gas Constant:p · V = m · R · T (1)This equation (1) can be modified to:
where
p = absolute pressure (N/m2, lb/ft2)
V = volume (m3, ft3)
m = mass (kg, slugs)
R = individual gas constant (J/kg.oK, ft.lb/slugs.oR)
T = absolute temperature (oK, oR)
p = ρ · R · T (2)The Individual Gas Constant - R - depends on the particular gas and is related to the molecular weight of the gas.
where the density
ρ = m / V (3)
Equation (1) can also be modified to
p1 V1 / T1 = p2 · V2 / T2 (4)expressing the relationship between different states for a given mass of gas.
The Ideal Gas Law and the Universal Gas Constant - Ru
The Universal Gas Constant is independent of the particular gas and is the same for all "perfect" gases. The Ideal Gas Law can be expressed with the Universal Gas Constant:p · V = n · Ru · T (5)
where
p = absolute pressure (N/m2, lb/ft2)
V = volume (m3, ft3)
n = is the number of moles of gas present
Ru = universal gas constant (J/mol.oK, lbf.ft/(lbmol.oR))
T = absolute temperature (oK, oR)
Example - The Ideal Gas Law
A tank with volume of 1 ft3 is filled with air compressed to a gauge pressure of 50 psi. The temperature in tank is 70 oF.The air density can be calculated with a transformation of the ideal gas law (2) to:
ρ = p / (R · T) (6)The weight of the air is the product of specific weight and the air volume. It can be calculated as:
ρ= [(50 (lb/in2) + 14.7 (lb/in2)) · 144 (in2/ft2)] / [1716 (ft.lb/slug.oR) · (70 + 460) (oR)]
= 0.0102 (slugs/ft3)
w = ρ · g · V (7)
w = 0.0102 (slugs/ft3) · 32.2 (ft/s2) · 1 (ft3)
= 0.32844 (slugs.ft/s2)
= 0.32844 (lb)
Note!
The Ideal Gas Law is accurate only at relatively low pressures and high temperatures. To account for the deviation from the ideal situation, another factor is included. It is called the Gas Compressibility Factor, or Z-factor. This correction factor is dependent on pressure and temperature for each gas considered.The True Gas Law, or the Non-Ideal Gas Law, becomes:
P · V = Z · n · R · T (7)
where
Z = Gas Compressibility Factor
n = number of moles of gas present
Vapor and Steam Introduction to vapor and steam
Vapor and Steam
there is no significant physical or chemical difference between a vapor and a gas.
Evaporation from fluids takes place when the liquid molecules at the liquid surface have enough momentum to overcome the intermolecular cohesive forces and escape to the atmosphere. When heat is added to the liquid the molecular momentum and the evaporation increases. A reduction of the pressure above a liquid will reduce the momentum needed for molecules to escape the liquid and increase the evaporation.
Common terms used in connection with vapor and steam:
Introduction to vapor and steam
Vapor is a gas -there is no significant physical or chemical difference between a vapor and a gas.
- a vapor is a substance in a gaseous state - at a condition where it is ordinarily liquid or solid
Evaporation from fluids takes place when the liquid molecules at the liquid surface have enough momentum to overcome the intermolecular cohesive forces and escape to the atmosphere. When heat is added to the liquid the molecular momentum and the evaporation increases. A reduction of the pressure above a liquid will reduce the momentum needed for molecules to escape the liquid and increase the evaporation.
- increasing the pressure above the liquid reduces the evaporation
Common terms used in connection with vapor and steam:
Boiling
- Boiling is formation of vapor bubbles within a fluid. Boiling is initiated when the absolute pressure in the fluid reaches the vapor pressure.
Saturated Vapor
- Vapor at the temperature of the boiling point which corresponds to its pressure.
Wet Saturated Vapor
- A wet saturated vapor carries liquid globules in suspension. A wet saturated vapor is a substance in the gaseous state which does not follow the general gas law.
Dry Saturated Vapor
- A dry saturated vapor is free from liquid particles. All particles are vaporized - any decrease in the vapor temperature or increase in the vapor pressure, will condensate liquid particles in the vapor. A dry saturated vapor is a substance in the gaseous state which does not follow the general gas law.
Superheated Vapor
- In superheated vapor the temperature is higher than the boiling point temperature corresponding to the pressure. The vapor can not exist in contact with the fluid, nor contain fluid particles. An increase in pressure or decrease in temperature will not - within limits - condensate out liquid particles in the vapor. Highly superheated vapors are gases that approximately follow the general gas law.
High Pressure Steam
- Steam where the pressure greatly exceeds the atmosphere pressure.
Low Pressure Steam
- Steam of which the pressure is less than, equal to, or not greatly above, that of the atmosphere.
The overall heat-transfer coefficient of a heat exchanger under operating conditions is reduced by fouling
Fouling and Heat Transfer
The overall heat-transfer coefficient of a heat exchanger under operating conditions is reduced by fouling
During operation with most liquids and some gases a dirt film
gradually builds up on the heat-transfer surface. The deposit is
referred to as fouling.
The increased thermal resistance of the deposit can generally be obtained only from actual tests or experience. The fouling factor can be determined from the relation
The increased thermal resistance of the deposit can generally be obtained only from actual tests or experience. The fouling factor can be determined from the relation
Rd = 1 / Ud - 1 / U (1)
where
Rd = fouling factor - or unit thermal resistance of the deposit (m2K/W)
Ud = thermal conductance of heat exchanger after fouling (W/m2K)
U = thermal conductance of clean heat exchanger (W/m2K)
(1) can also be expressed as:
Ud = 1 / (Rd + 1 / U)
Typical Fouling Factors
- Alcohol vapors : Rd = 0.00009 (m2K/W)
- Boiler feed water, treated above 325 K : Rd = 0.0002 (m2K/W)
- Fuel oil : Rd = 0.0009 (m2K/W)
- Industrial air : Rd = 0.0004 (m2K/W)
- Quenching oil : Rd = 0.0007 (m2K/W)
- Refrigerating liquid : Rd = 0.0002 (m2K/W)
- Seawater below 325 K : Rd = 0.00009 (m2K/W)
- Seawater above 325 K : Rd = 0.0002 (m2K/W)
- Steam : Rd = 0.00009 (m2K/W)
Monitor™ economic calculations answer common questions about the cost of fouling,
Economic Calculations
Monitor™ economic calculations answer common questions about the
cost of fouling, the benefits to be gained from cleaning and help to develop an
optimum cleaning strategy.
Cleaning Economics Reports
Monitor™ Cleaning Economics calculations determine the effects of cleaning exchangers in
the Network. These are shown in tabular form
and include:
the cost of removing exchangers for cleaning the savings that could be made by cleaning selected exchangers the optimum cleaning cycles for each exchanger and for user-defined groups of exchangers.
In
addition, one of the standard spreadsheet reports
is the Fouling Cost Summary which shows the additional costs that have been
incurred over a range of cases for the furnace to make up the duty lost.
Economic Data Required
The
Cleaning Economic calculations require the following data:
Globally:
The Fuel Cost and the Furnace Efficiency are used when generating all economic reports. The Length of Plant Run is only used in the optimum cleaning cycle report. Fuel Cost expressed in $ per unit of duty. The default value is the Solomon value for fuel oil. Furnace Efficiency. The fuel cost is divided by this value to obtain the total cost of the fuel. Length of Plant Run expressed as number of days between plant shutdowns. This is used in the optimum cleaning cycle calculation.
For each exchanger:
Date Last Cleaned. This is used in the optimum cleaning cycle report. Days to Clean. The number of days that an exchanger will be out of service when it is removed for cleaning. This is used in the optimum cleaning cycle report. Cleaning Cost. The fixed costs (man time, cleaning materials, etc.) associated with removing and cleaning an exchanger. This does not include additional costs incurred by the reduced Network duty. This cost is used in the optimum cleaning cycle report. Clean Fouling Factor for the exchanger when returned to service after cleaning. This is used in the Cleaning Economics calculation and the optimum cleaning cycle report.
How Cleaning Economics are Calculated
Fouling
factors are first calculated for a selected Case. These are used to
calculate temperatures for all exchangers and at the furnace inlet.
Cost of removing exchangers for cleaning
The
Network is solved and the furnace run-up temperature calculated with each
exchanger in turn bypassed. This determines the effect of removing the
exchangers for cleaning in terms of lost enthalpy at the furnace inlet, also
expressed as $/day. The program also calculates the amount by which the throughput
would have to be reduced in order to maintain the furnace inlet temperature at
its previous level.
Savings from cleaning
The
fouling factor of each exchanger in turn is then set to its clean value and the
Network is solved to obtain the increase in duty that this would produce at the
furnace inlet. This is shown as extra throughput which could be achieved
and $/day.
Optimum cleaning cycles
The
above results are then used, along with fixed costs, to calculate the optimum
cleaning cycles for each exchanger. The optimum cycle is that which
minimises the annualised cost of fouling. By default, each exchanger is cleaned
in turn. Combinations of exchangers to be cleaned in addition to
individual exchangers are defined in the User Defined Cleaning Economics
Combinations Window.
Flexible Output
MONITOR's
output capabilities are extensive.
-
You can export the PFD drawing to PowerPoint so that you can use it in a presentation.
-
You can get results tables displayed directly on the screen.
-
You can have a summary of Reconciliation, Fouling and NFIT runs for a range of cases.
-
You can plot results from a range of cases to view trends.
Output
can be produced
in any combination of Units of Measurement.
Summary:
|
Calculation History | ||
Plots:
|
|||
User-Defined Plots |
Tabular Output
You
can get the results of the current case displayed as a table directly on the screen.
You can export these results to Word or to a Text file.
Input Data Reprint
To
enable you to check all your data, Monitor prints it all out at the start of
the main results output.
The
network data include:
Case data
include:
|
|
|
Reconciliation
Monitor uses measured plant temperatures and flowrates to calculate heat exchanger fouling factors.
The Data Reconciliation calculation identifies inconsistencies in the input
data and enables you to obtain a more consistent set of data for the fouling calculation.
Reconciliation
output shows the duties calculated from the supplied flowrates and temperatures for each side of target
exchanger and the differences between them. It also shows the differences between the target and calculated temperatures of
the products of target mixers.
The
same data are then shown after the reconciliation has been completed. The
table shows by how much feed stream temperatures and flowrates and
splitter ratios have been changed to achieve a reconciled data set.
|
|
|
Fouling
After
a reprint of the input data, the fouling report shows tabular results for each type of heat exchanger in
turn, followed by results for all other types of unit operation in turn.
Finally, the temperatures, pressures, flows and properties are presented for all the streams in the Network.
Heat
exchanger results include:
|
|
|
Normalised Output
Normalisation
is the technique Monitor uses to remove the effect of the changes in external parameters,
such as crude and product variations, to determine a true picture of the
degradation of network performance due to fouling alone.
The
calculated fouling factors from each case are superimposed onto the feeds
from a selected base case and the resultant temperatures reported.
Normalisation
output includes:
|
|
|
Cleaning Economics
Cleaning Economics
calculations determine the effect of cleaning exchangers in the Network
and an optimum cleaning cycle for each exchanger.
Cleaning
output includes:
|
|
|
Splitter Optimisation
Splitter
Optimisation determines splitter product ratios which maximise the heat recovery of the Network.
This minimises the required furnace duty for the Network.
Optimisation
output includes:
|
|
|
Calculation Histories
This
report summarises the Reconciliation and/or Fouling and/or NFIT results
for all cases within a range you select. It
is particularly useful for troubleshooting data errors.
The
report here shows a range of Data Reconciliation results, including some
failed cases.
You
can choose to display all cases or just failed cases.
|
|
|
|
||
Plotted Output |
||
For
monitoring over a time period, by
far the most meaningful form of output is that presented in graphical
format.
There are a number of standard, predefined reports.
You may also define your own reports to include the parameters, units and/or streams that you require.
The
data for the selected report are written to a text file which is then
opened automatically in Excel.
A plot is created for each set of data in the spreadsheet. You may
then modify and save the workbook or copy plots or data into other
applications.
The
standard reports are:
|
||
Reconciliation
This report compares results for data reconciliation over the range of Cases.
It shows:
|
||
Heat Transfer
This report contains heat transfer data for all the exchangers in the Network and any normalised furnace inlet temperatures.
For each exchanger
there are plots for:
|
|
|
Fouling Cost
This report shows the additional costs
incurred when a furnace makes up the duty lost because of fouling.
The spreadsheet plots the following on separate worksheets:
|
|
|
Stream Temperatures
This report shows the temperatures of all streams in the Network.
Feed
streams, product streams and internal streams are presented separately and are plotted on separate worksheets.
Compare
this plot of the actual furnace inlet stream temperatures with the
normalised plot abov. This shows the benefit of normalisation to
give a more meaningful presentation of the true effect of fouling.
|
||
Weight and Volume Flow Rates
These
two
reports show the weight and volume flowrates of all streams in the
Network. Feed streams, product streams and internal streams are
presented separately and are plotted on separate worksheets.
|
||
Weight
Flowrates
|
||
Volume Flowrates | ||
Pressures
The pressure at the inlet and outlet of each exchanger is listed on
this report along with pressure drops. The plots for each exchanger are on separate worksheets and show:
|
|
|
User Defined Spreadsheet Outputs
If
none of the standard spreadsheet reports meets your requirements, you may define your own reports.
You may
specify a
|
Subscribe to:
Posts (Atom)