Advanced data validation and reconciliation process

The workflow of an advanced data validation and reconciliation process.

Solution - Material Balance Problem #1

Material Balance Problem #1

A mixture containing 45% benzene and 55 % tolune by mass is fed to distillation column. A overhead stream of 95 % benzene is produced, and 8% of benzene fed to column leaves in bottom stream. Feed rate is 2000 Kg/Hr.
Determine  -
i . Overhead flow rate
ii. Mass flow rate of benzene and tolune in the bottom stream

Chemical Basis for Love

Recent studies in neuroscience have indicated that as people fall in love, the brain consistently releases a certain set of chemicals, including pheromones, dopamine, norepinephrine, and serotonin, which act in a manner similar to amphetamines, stimulating the brain’s pleasure center and leading to side effects such as increased heart rate, loss of appetite and sleep,and an intense feeling of excitement. Research has indicated that this stage generally lasts from one and a half to three years.
Attachment is generally based on commitments such as marriage and children, or on mutual friendship based on things like shared interests. It has been linked to higher levels of the chemicals oxytocin and vasopressin to a greater degree than short-term relationships have. Enzo Emanuele and coworkers reported the protein molecule known as the nerve growth factor (NGF) has high levels when people first fall in love, but these return to previous levels after one year.
Hope everyone has planned/is planning their good times with ‘all’ their loved ones. Not only for the coming valentine’s day celebrations but for the whole of the year (just a year, not life: that’s too much of a planning already ! )
Have a great time !!

Sulfur recovery

 

Sulfur recovery refers to the conversion of hydrogen sulfide (H2S) to elemental sulfur. Hydrogen sulfide is a byproduct of processing natural gas and refining high-sulfur crude oils. The most common conversion method used is the Claus process. Approximately 90 to 95 percent of recovered sulfur is produced by the Claus process. The Claus process typically recovers 95 to 97 percent of the hydrogen sulfide feedstream.

Over 5.9 million megagrams (Mg) (6.5 million tons) of sulfur were recovered in 1989, representing about 63 percent of the total elemental sulfur market in the U. S. The remainder was mined or imported. The average production rate of a sulfur recovery plant in the U. S. varies from  51 to 203 Mg (56 to 224 tons) per day.

 

Claus Sulfur recovery unit

The process consists of multistage catalytic oxidation of hydrogen sulfide according to

the following overall reaction:

2H2S +  O2 ® 2S + 2H2O                                                         (1)

Each catalytic stage consists of a gas reheater, a catalyst chamber, and a condenser.

The Claus process involves burning one-third of the H2S with air in a reactor furnace to form

sulfur dioxide (SO2) according to the following reaction:

2H2S + 3O2 ® 2SO2 +  2H2O +  heat                                         (2)

The furnace normally operates at combustion chamber temperatures ranging from 980 to 1540°C (1800 to 2800°F) with pressures rarely higher than 70 kilopascals (kPa) (10 pounds per square inch absolute). Before entering a sulfur condenser, hot gas from the combustion chamber is quenched in a waste heat boiler that generates high to medium pressure steam. About 80 percent of the heat released could be recovered as useful energy. Liquid sulfur from the condenser runs through a seal leg into a covered pit from which it is pumped to trucks or railcars for shipment to end users. Approximately 65 to 70 percent of the sulfur is recovered. The cooled gases exiting the condenser are then sent to the catalyst beds. The remaining uncombusted two-thirds of the hydrogen sulfide undergoes Claus reaction (reacts with SO2) to form elemental sulfur as follows:

2H2S +  SO2 ¬®3S +  2H2O +  heat                                        (3)

The catalytic reactors operate at lower temperatures, ranging from 200 to 315°C (400 to 600°F).

Alumina or bauxite is sometimes used as a catalyst. Because this reaction represents an equilibrium chemical reaction, it is not possible for a Claus plant to convert all the incoming sulfur compounds to elemental sulfur. Therefore, 2 or more stages are used in series to recover the sulfur. Each catalytic stage can recover half to two-thirds of the incoming sulfur. The number of catalytic stages depends upon the level of conversion desired. It is estimated that 95 to 97 percent overall recovery can be achieved depending on the number of catalytic reaction stages and the type of reheating method used.

If the sulfur recovery unit is located in a natural gas processing plant, the type of reheat employed is typically either auxiliary burners or heat exchangers, with steam reheat being used occasionally. If the sulfur recovery unit is located in a crude oil refinery, the typical reheat scheme uses 3536 to 4223 kPa (500 to 600 pounds per square inch guage [psig]) steam for reheating purposes. Most plants are now built with 2 catalytic stages, although some air quality jurisdictions require 3. From the condenser of the final catalytic stage, the process stream passes to some form of tailgas treatment process. The tailgas, containing H2S, SO2, sulfur vapor, and traces of other sulfur compounds formed in the combustion section, escapes with the inert gases from the tail end of the plant. Thus, it is frequently necessary to follow the Claus unit with a tailgas cleanup unit to achieve higher recovery. In addition to the oxidation of H2S to SO2 and the reaction of SO2 with H2S in the reaction furnace, many other side reactions can and do occur in the furnace. Several of these possible side reactions are:

CO2  +  H2S ® COS +  H2O                                                     (4)

COS + H2S ® CS2 +  H2O                                                        (5)

2COS ® CO2 + CS2                                                                                       (6)

FUEL OIL ADDITIVE FCS- 500 ( ENCHEM SOLUTIONS)

Find out how FCS-500 can help solve your oil problems.


The varied uses of the many grades of oil stocks throughout the world make it impossible for a single formulation, such as FCS-500, to be able to solve every need. ENCHEM SOLUTIONS is ready with the technical advice and formulating capability to respond to your particular performance problems. Please call us regarding any questions about FCS-500 or our other additives.


Problems -  1. Soot Deposition on surfaces?

The furnace oil produced at Indian Refineries contains short chain hydrocarbons (used as flux to reduce viscosity) blended with the mixture of high boiling point hydrocarbons containing asphaltic and long chain waxes. These hydrocarbons have high molecular weight and boil at very high temperature and hence are very difficult to burn completely. The asphalts are a long chain of aromatic hydrocarbons which are highly deficient in hydrogen and hence have high CCR value. As the thrust in refining sector is towards enhancement of yield of middle distillates by employing secondary processes such as fluidized catalytic cracking, hydrocracking, delayed coking, visbreaking etc., the quality of fuel oils suffer; consequently, they become more and more difficult to burn. This results in high CCR value of the fuel oil, thus leaving more and more soot deposits after combustion.

Solution -

In order to combat such problem, it becomes desirable to use fuel additives which can help in making the fuels burn more effectively by using the same combustion device.

FCS – 500, helps … 

p            In enhanced degree of atomization, with the result that more surface area/volume can be created for combustion in the available combustion space.

p            To blow away the residual soot deposits from the combustion devices (burner tips etc.); means that they should possess dispersant properties.

Problem –2. Storage Sludge formation?

As the furnace oil contains heavy hydrocarbons/waxes, they have the tendency to cause stratification in storage tanks during storage. As the furnace oil also contains small amounts of water and sediments, the process of stratification gives birth to sludge formation. Over a period of time, this sludge grows heavier and settles down in the fuel oil storage tank. As the time elapses, its volume increases, with the result its slugs enter the combustion system along with the fuel and cause all sorts of problems in the combustion system.

Solution -
The fuel additive, FCS – 500 when mixed in right proportion, be able to combat the problem of sludge generation by making a proper emulsion of these compounds and inhibit its growth.

Problem –3. Water in residual fuel?

Solution –
The water in residual fuels passes through delivery and ignition systems because of the surfactants in FCS-500.

The surface tension of condensation and free-standing water is reduced (proven through scientific tests), allowing it to pass through the system with atomization of the fuel at the burner nozzles. This inhibits corrosion in the fuel system and aids the combustion process.

Problem  4 - Low flow ability of residual oil stocks ?

Solution :

Flow ability is improved by the organic dispersant in FCS-500.The formation of viscous emulsions and the stratification that often occurs in residual fuels is greatly reduced. Dispersing long chain, heavy hydrocarbons prevents them from settling into sludge. Tanks, lines, nozzles, and pre-ignition components remain free of sludge and deposits.







Problem  5 – Formation of Slag ( molten oxides of Vanadium)

Solution :

The combustion catalyst is a solution of organic compounds which are dissolved in a pure hydrocarbon solvent, making them mixable with oils. These organic ions dissolved in solution cause more rapid and complete burning of the fuel and provide significant reductions in the corrosive effects of high sulfur, high vanadium and sodium content of the residual fuel.
Control of deposits during the combustion process is affected by the organic catalyst. This catalyst changes the nature of the vanadium oxides formed during the combustion process. The vanadium pentoxide, which has a relatively low melting point, is the primary cause of slag formation in combustion chambers. In liquid or molten form, it acts as a binder and a powerful corrosive agent. The organic catalyst in FCS-500 reacts with the vanadium to form high-melting-point vanadates that deposit in dry friable form, thus inhibiting the formation of molten vanadium slag.
Furthermore, existing deposits containing vanadium will usually be reached by the action of the FCS-500 catalyst's vapors and drop off in pieces over a period of a few weeks.

Problem  6 - Hazardous SO3 emissions, the primary cause of acid rain?

Solution :

When molten vanadium pentoxide is present, it acts as a catalyst to change the SO₂ in the presence of excess air to the more objectionable sulfur trioxide (SO₃), which then combines with moisture to form sulfuric acid. This, of course, has a very serious corrosive effect on metal surfaces and the environment. The dry, friable form of vanadates are deposited far less on combustion chamber surfaces, thus substantially reducing the conversion of SO₂ to SO₃
Additional improvement in the SO₂/SO₃ ratio can be made by the reduction of excess air. The combustion improving capability of FCS-500 will allow air requirements to be reduced. Less air (and therefore less unused oxygen in the ignition process) causes reduced SO₃ formation.







Problem 7 – Fuel Economy?

Lower air requirements and more efficient burning of fuel stocks add up to significant savings. The combustion improvement capability of FCS-500 will allow excess air to be reduced. This helps overcome heat loss up the stack by reducing its velocity past the heating surfaces.
Saving in fuel consumption achieved by FCS-500 is to the tune of 5%.

Typical analysis of residue furnace oil/LSHS

	Parameter	FO	LSHS
1	Petroleum based low  viscosity  flux (%)	55-60	0-5
2	Wax (%)	0-5	75-80
3	Asphaltenes (%)	35-40	negligible
4	Polyaromatics (%)                                 (other than asphaltenes)	---	20-25
5	Sediments & Moisture (max) (%)	0.5	0.5

                                  

What does FCS - 500 contain?

The residue fuel oil additive, FCS -500 developed and manufactured by M/s. ENCHEM SOLUTIONS contains organo-amino based resins as fuel stabilizer and biochemical surfactants, Speciality Chemicals (Organo-silicon) as fuel conditioner that provide following properties to the fuel oils

1.     Storage stability and homogenization of fuel,

2.     Enhanced atomization property for improved geometry of flame,

3.     Improved combustion efficiency and

4.     Detergency to the residual soot formed.

FCS - 500 does not contain metallic or phosphorous compounds and hence,   it is absolutely safe for the metallurgy of boiler tubes. It helps burn away the residual carbon (CCR) formed during the combustion process, resulting in improved combustion efficiency and save fuel to the tune of between 4.5 to 5%.

Physical Properties :

Specific Gravity @ 15 deg. C    :    0.83 - 0.85

Flash Point  ( deg. C)                :     59 

Appearance                              :    Yellow to amber.
Form                                        :    Clear liquid.
Odour                                                :    Mild amine odour.

Major Benefits of FCS – 500

p   Improved combustion efficiency resulting in

1.     Lesser soot generation and lower TPM in flue gases.

2.     Reduced soot blowing frequency.

3.     Sustenance of optimum boiler efficiency.

p     Alleviation of choking of burner tips due to fuel carbonization.

p     Fuel oil savings to the tune of 5%.

p     COMPLETE homogenization of fuel oil and prevention and depletion of sludge formation in storage tanks

Experienced-Based Rules of Chemical Engineering

This article was send by Jerry M on my email.

Experience is typically what turns a good engineer into a great engineer. An engineer that can look at a pipe and a flow meter and guess the pressure drop within 5%. Someone who can at least estimate the size of a vessel without doing any calculations. Here, some of these rules will be shared with you along with some of my own. Now, be aware that these rules are for estimation and are not necessary meant to replace rigorous calculations when such calculations should be performed. But at many stages of analysis and design, these rules can save you hours and hours.

Materials of Construction
Material	Advantage		Disadvantage
Carbon Steel	Low cost, easy to fabricate, abundant, most common material. Resists most alkaline environments well.		Very poor resistance to acids and stronger alkaline streams. More brittle than other materials, especially at low temperatures.
Stainless Steel	Relatively low cost, still easy to fabricate. Resist a wider variety of environments than carbon steel. Available is many different types.		No resistance to chlorides, and resistance decreases significantly at higher temperatures.
254 SMO (Avesta)	Moderate cost, still easy to fabricate. Resistance is better over a wider range of concentrations and temperatures compared to stainless steel.		Little resistance to chlorides, and resistance at higher temperatures could be improved.
Titanium	Very good resistance to chlorides (widely used in seawater applications). Strength allows it to be fabricated at smaller thickness.		While the material is moderately expensive, fabrication is difficult. Much of cost will be in welding labor.
Pd stabilized Titanium	Superior resistance to chlorides, even at higher temperatures. Is often used on sea water application where Titanium's resistance may not be acceptable.		Very expensive material and fabrication is again difficult and expensive.
Nickel	Very good resistance to high temperature caustic streams.		Moderate to high expense. Difficult to weld.
Hastelloy Alloy	Very wide range to choose from. Some have been specifically developed for acid services where other materials have failed.		Fairly expensive alloys. Their use must be justified. Most are easy to weld.
Graphite	One of the few materials capable of withstanding weak HCl streams.		Brittle, very expensive, and very difficult to fabricate. Some stream components have been know to diffusion through some types of graphites.
Tantalum	Superior resistance to very harsh services where no other material is acceptable.		Extremely expensive, must be absolutely necessary.

Cooling Towers
A. With industrial cooling towers, cooling to 90% of the ambient air saturation level is possible.
B. Relative tower size is dependent on the water temperature approach to the wet bulb temperature:
Twater-Twb	Relative Size
5	2.4
15	1.0
25	0.55
C. Water circulation rates are generally 2-4 GPM/sq. ft (81-162 L/min m2) and air velocities are usually 5-7 ft/s (1.5-2.0 m/s)
D. Countercurrent induced draft towers are the most common. These towers are capable of cooling to within 2 °F (1.1 °C) of the wet bulb temperature. A 5-10 °F (2.8-5.5 °C) approach is more common.
E. Evaporation losses are about 1% by mass of the circulation rate for every 10 °F (5.5 °C) of cooling. Drift losses are around 0.25% of the circulation rate. A blowdown of about 3% of the circulation rate is needed to prevent salt and chemical treatment buildup.

Conveyors

A. Pneumatic conveyors are best suited for high capacity applications over distances of up to about 400 ft. Pneumatic conveying is also appropriate for multiple sources and destinations. Vacuum or low pressure (6-12 psig or 0.4 to 0.8 bar) is used for generate air velocities from 35 to 120 ft/s (10.7-36.6 m/s). Air requirements are usually in the range of 1 to 7 cubic feet of air per cubic foot of solids (0.03 to 0.5 cubic meters of air per cubic meter of solids).

B. Drag-type conveyors (Redler) are completed enclosed and suited to short distances. Sizes range from 3 to 19 inches square (75 to 480 mm). Travel velocities can be from 30 to 250 ft/min (10 to 75 meters/min). The power requirement for these conveyors is higher than other types.

C. Bucket elevators are generally used for the vertical transport of sticky or abrasive materials. With a bucket measuring 20 in x 20 in (500 mm x 500 mm), capacities of 1000 cubic feet/hr (28 cubic meters/hr) can be reached at speeds of 100 ft/min (30 m/min). Speeds up to 300 ft/min (90 m/min) are possible.

D. Belt conveyors can be used for high capacity and long distance transports. Inclines up to 30° are possible. A 24 in (635 mm) belt can transport 3000 cu. ft./h (85 cu m/h) at speeds of 100 ft/min (30.5 m/min). Speeds can be as high as 600 ft/min (183 m/min). Power consumption is relatively low.

E. Screw conveyors can be used for sticky or abrasive solids for transports up to 150 ft (46 m). Inclines can be up to about 20°. A 12 in (305 mm) diameter screw conveyor can transport 1000-3000 cu. ft./h (28-85 cu. m/h) at around 40-60 rpm.

Crystallization

A. During most crystallizations, C/Csat (concentration/saturated concentration) is kept near 1.02 to 1.05

B. Crystal growth rates and crystal sizes are controlled by limiting the degree of supersaturation.

C. During crystallization by cooling, the temperature of the solution is kept 1-2 °F (0.5-1.2 °C) below the saturation point at the given concentration.

D. A generally acceptable crystal growth rate is 0.10 - 0.80 mm/h

Drivers and Power Recovery

A. Efficiencies: 85-95% for motors, 40-75% for steam turbines, 28-38% for gas engines and turbines.

B. Electric motors are nearly always used for under 100 HP (75 kW). They are available up to 20,000 HP (14,915 kW).

C. Induction motors are most popular. Synchronous motors have speeds as low as 150 rpm at ratings above 50 HP (37.3 kW) only. Synchronous motors are good for low speed reciprocating compressors.

D. Steam turbines are seldom used below 100 HP (75 kW). Their speeds can be controlled and they make good spares for motors in case of a power failure.

E. Gas expanders may be justified for recovering several hundred horsepower. At lower recoveries, pressure let down will most likely be through a throttling valve.

Drying of Solids

A. Spray dryer have drying times of a few seconds. Rotary dryers have drying times ranging from a few minutes to up to an hour.

B. Continuous tray and belt dryers have drying times of 10-200 minutes for granular materials or 3-15 mm pellets.

C. Drum dryers used for highly viscous fluids use contact times of 3-12 seconds and produce flakes 1-3 mm thick. Diameters are generally 1.5-5 ft (0.5 - 1.5 m). Rotation speeds are 2-10 rpm and the maximum evaporation capacity is around 3000 lb/h (1363 kg/h).

D. Rotary cylindrical dryers operate with air velocities of 5-10 ft/s (1.5-3 m/s), up to 35 ft/s (10.5 m/s). Residence times range from 5-90 min. For initial design purposes, an 85% free cross sectional area is used. Countercurrent design should yield an exit gas temperature that is 18-35 °F (10-20 °C) above the solids temperature. Parallel flow should yield an exiting solids temperature of 212 °F (100 °C). Rotation speeds of 4-5 rpm are common. The product of rpm and diameter (in feet) should be 15-25.

E. Pneumatic conveying dryers are appropriate for particles 1-3 mm in diameter and in some cases up to 10 mm. Air velocities are usually 33-100 ft/s (10-30 m/s). Single pass residence time is typically near one minute. Size range from 0.6-1.0 ft (0.2-0.3 m) in diameter by 3.3-125 ft (1-38 m) in length.

F. Fluidized bed dryer’s work well with particles up to 4.0 mm in diameter. Designing for a gas velocity that is 1.7-2 times the minimum fluidization velocity is good practice. Normally, drying times of 1-2 minutes are sufficient in continuous operation.

Drum Type Vessels
A. Liquid drums are usually horizontal. Gas/Liquid separators are usually vertical
B. Optimum Length/Diameter ratio is usually 3, range is 2.5 to 5
C. Holdup time is 5 minutes for half full reflux drums and gas/liquid separators
Design for a 5-10 minute holdup for drums feeding another column
D. For drums feeding a furnace, a holdup of 30 minutes is a good estimate
E. Knockout drum in front of compressors should be designed for a holdup of
10 times the liquid volume passing per minute.
F. Liquid/Liquid separators should be designed for settling velocities of 2-3 inches/min
G. Gas velocities in gas/liquid separators, velocity = k (liquid density/(vapor density-1))^0.5,
			where k is 0.35 with horizontal mesh deentrainers and 0.167 with vertical mesh deentrainers. k is 0.1 without mesh deentrainers and velocity is in ft/s
H. A six inch mesh pad thickness is very popular for such vessels
I. For positive pressure separations, disengagement spaces of 6-18 inches before the mesh pad and 12 inches after the pad are generally suitable.

Electric Motors and Turbines
A. Efficiencies range from 85-95% for electric motors, 42-78% for steam turbines
28-38% for gas engines and turbines
B. For services under 75 kW (100 hp), electric motors are almost always used.
They can be used for services up to about 15000 kW (20000 hp)
C. Turbines can be justified in services where they will yield several hundred
horsepowers. Otherwise, throttle valves are used to release pressure.
D. A quick estimate of the energy available to a turbine is given by:
where: Delta H = Actual available energy, Btu/lb
Cp = Heat Capacity at constant pressure, Btu/lb 0F
T1 = Inlet temperature, 0R
P1 = Inlet pressure, psia
P2 = Outlet pressure, psia
K = Cp/Cv

Evaporation

A. Most popular types are long tube vertical with natural or forced circulation. Tubes range from 3/4" to 2.5" (19-63 mm) in diameter and 12-30 ft (3.6-9.1 m) in length.

B. Forced circulation tube velocities are generally in the 15-20 ft/s (4.5-6 m/s) range.

C. Boiling Point Elevation (BPE) as a result of having dissolved solids must be accounted for in the differences between the solution temperature and the temperature of the saturated vapor.

D. BPE's greater than 7 °F (3.9 °C) usually result in 4-6 effects in series (feed-forward) as an economical solution. With smaller BPE's, more effects in series are typically more economical, depending on the cost of steam.

E. Reverse feed results in the more concentrated solution being heated with the hottest steam to minimize surface area. However, the solution must be pumped from one stage to the next.

F. Interstage steam pressures can be increased with ejectors (20-30% efficient) or mechanical compressors (70-75% efficient).

Filtration

A. Initially, processes are classified according to their cake buildup in a laboratory vacuum leaf filter :  0.10 - 10.0 cm/s (rapid), 0.10-10.0 cm/min (medium), 0.10-10.0 cm/h (slow)

B. Continuous filtration methods should not be used if 0.35 cm of cake cannot be formed in less than 5 minutes.

C. Belts, top feed drums, and pusher-type centrifuges are best for rapid filtering.

D. Vacuum drums and disk or peeler-type centrifuges are best for medium filtering.

E. Pressure filters or sedimenting centrifuges are best for slow filtering.

F. Cartridges, precoat drums, and sand filters can be used for clarification duties with negligible buildup.

G. Finely ground mineral ores can utilize rotary drum rates of 1500 lb/dat ft2 (7335 kg/day m2) at 20 rev/h and 18-25 in Hg (457-635 mm Hg) vacuum.

H. Course solids and crystals can be filtered at rates of 6000 lb/day ft2 (29,340 kg/day m2) at 20 rev/h and 2-6 in Hg (51-152 mm Hg) vacuum.

Mixing and Agitation
A. Mild agitation results from superficial fluid velocities of 0.10-0.20 ft/s (0.03-0.06 m/s). Intense agitation results from velocities of 0.70-1.0 ft/s (0.21-0.30 m/s).
B. For baffled tanks, agitation intensity is measured by power input and impeller tip speeds:
	Power Requirements		Tip Speeds
	HP/1000 gal	kW/m3	ft/s	m/s
Blending	0.2-0.5	0.033-0.082	-----	----
Homogeneous Reaction	0.5-1.5	0.082-0.247	7.5-10.0	2.29-3.05
Reaction w/ Heat Transfer	1.5-5.0	0.247-0.824	10.0-15.0	3.05-4.57
Liquid-Liquid Mixtures	5.0	0.824	15.0-20.0	4.57-6.09
Liquid-Gas Mixtures	5.0-10.0	0.824-1.647	15.0-20.0	4.57-6.09
Slurries	10.0	1.647	-----	----
C. Various geometries of an agitated tank relative to diameter (D) of the vessel include: Liquid Level = D Turbine Impeller Diameter = D/3 Impeller Level Above Bottom = D/3 Impeller Blade Width = D/15 Four Vertical Baffle Width = D/10
D. For settling velocities around 0.03 ft/s, solids suspension can be accomplished with turbine or propeller impellers. For settling velocities above 0.15 ft/s, intense propeller agitation is needed.
E. Power to mix a fluid of gas and liquid can be 25-50% less than the power to mix the liquid alone.

Pressure and Storage Vessels
Pressure Vessels
A. Design Temperatures between -30 and 345 °C (-22 to 653 °F) is typically about
25 °C (77 °F) above maximum operating temperature, margins increase above this range
B. Design pressure is 10% or 0.69 to 1.7 bar (10 to 25 psi) above the maximum operating
pressure, whichever is greater. The maximum operating pressure is taken as 1.7 bar (25 psi)
above the normal operation pressure.
C. For vacuum operations, design pressures are 1 barg (15 psig) to full vacuum
D. Minimum thicknesses for maintaining tank structure are:
	6.4 mm (0.25 in) for 1.07 m (42 in) diameter and under
	8.1 mm (0.32 in) for 1.07-1.52 m (42-60 in) diameter
	9.7 mm (0.38 in) for diameters over 1.52 m (60 in)
E. Allowable working stresses are taken as 1/4 of the ultimate strength of the material
F. Maximum allowable working stresses:
	Temperature	-20 to 650 °F	750 °F	850 °F	1000 °F
		-30 to 345 °C	400 °C	455 °C	540 °C
	CS SA203	18759 psi	15650 psi	9950 psi	2500 psi
		1290 bar	1070 bar	686 bar	273 bar
	302 SS	18750 psi	18750 psi	15950 psi	6250 psi
		1290 bar	1290 bar	1100 bar	431 bar
G. Thickness based on pressure and radius is given by:

	where pressure is in psig, radius in inches, stress in psi, corrosion allowance in inches.
	**Weld Efficiency can usually be taken as 0.85 for initial design work
H. Guidelines for corrosion allowances are as follows: 0.35 in (9 mm) for known corrosive fluids, 0.15 in (4 mm) for non-corrosive fluids, and 0.06 in (1.5 mm) for steam drums and air receivers.
Storage Vessels
I. For less than 3.8 m3 (1000 gallons) use vertical tanks on legs
J. Between 3.8 m3 and 38 m3 (1000 to 10,000 gallons) use horizontal tanks on concrete supports
K. Beyond 38 m3 (10,000 gallons) use vertical tanks on concrete pads
L. Liquids with low vapor pressures use tanks with floating roofs.
M. Raw material feed tanks are often specified for 30 days feed supplies
N. Storage tank capacity should be at 1.5 times the capacity of mobile supply vessels.
For example, 28.4 m3 (7500 gallon) tanker truck, 130 m3 (34,500 gallon) rail cars

Piping
A. Liquid lines should be sized for a velocity of (5+D/3) ft/s and a pressure drop of
2.0 psi/100 ft of pipe at pump discharges
At the pump suction, size for (1.3+D/6) ft/s and a pressure drop of 0.4 psi/100 ft of pipe
**D is pipe diameter in inches
B. Steam or gas lines can be sized for 20D ft/s and pressure drops of 0.5 psi/100 ft of pipe
C. Limits on superheated, dry steam or gas line should be 61 m/s (200 ft/s) and a pressure drop of 0.1 bar/100 m or 0.5 psi/100 ft of pipe. Saturated steam lines should be limited to 37 m/s (120 ft/s) to avoid erosion.
D. For turbulent flow in commercial steel pipes, use the following:

E. For two phase flow, an estimate often used is Lockhart and Martinelli:
First, the pressure drops are calculated as if each phase exist alone in the pipe, then

F. Control valves require at least 0.69 bar (10 psi) pressure drop for sufficient control

G. Flange ratings include 10, 20, 40, 103, and 175 bar (150, 300, 600, 1500, and 2500 psig)

H. Globe valves are most commonly used for gases and when tight shutoff is required. Gate valves are common for most other services.

I. Screwed fitting are generally used for line sizes 2 inches and smaller. Larger connections should utilize flanges or welding to eliminate leakage.

J. Pipe Schedule Number = 1000P/S (approximate) where P is the internal pressure rating in psig and S is the allowable working stress of the material is psi. Schedule 40 is the most common.
Pumps
A. Power estimates for pumping liquids:
kW=(1.67)[Flow (m3/min)][Pressure drop (bar)]/Efficiency
hp=[Flow (gpm)][Pressure drop (psi)]/1714 (Efficiency)
**Efficiency expressed as a fraction in these relations
B. NPSH=(pressure at impeller eye-vapor pressure)/(density*gravitational constant)
Common range is 1.2 to 6.1 m (4-20 ft) of liquid
C. An equation developed for efficiency based on the GPSA Engineering Data Book is:
Efficiency = 80-0.2855F+.000378FG-.000000238FG^2+.000539F^2-.000000639(F^2)G+
	.0000000004(F^2)(G^2)
where Efficiency is in fraction form, F is developed head in feet, G is flow in GPM
Ranges of applicability are F=50-300 ft and G=100-1000 GPM
Error documented at 3.5%
D. Centrifugal pumps: Single stage for 0.057-18.9 m3/min (15-5000 GPM), 152 m (500 ft)
maximum head; For flow of 0.076-41.6 m3/min (20-11,000 GPM) use multistage, 1675 m (5500 ft)
maximum head; Efficiencies of 45% at 0.378 m3/min (100 GPM), 70% at 1.89 m3/min (500 GPM), 80% at 37.8 m3/min (10,000 GPM).
E. Axial pumps can be used for flows of 0.076-378 m3/min (20-100,000 GPM)
Expect heads up to 12 m (40 ft) and efficiencies of about 65-85%
F. Rotary pumps can be used for flows of 0.00378-18.9 m3/min (1-5000 GPM)
Expect heads up to 15,200 m (50,000 ft) and efficiencies of about 50-80%
G. Reciporating pumps can be used for 0.0378-37.8 m3/min (10-100,000 GPM)
Expect heads up to 300,000 m (1,000,000 ft).
Efficiencies: 70% at 7.46 kW (10 hp), 85% at 37.3 kW (50 hp), and 90% at 373 kW (500 hp)

Compressors and Vacuum Equipment
A. The following chart is used to determine what type of compressor is to be used:

B. Fans should be used to raise pressure about 3% (12 in water), blowers to raise to less than 2.75 barg (40 psig), and compressors to higher pressures.
C. The theoretical reversible adiabatic power is estimated by:
Power = m z1 R T1 [({P2 / P1}a - 1)] / a
	where:
	T1 is the inlet temperature, R is the gas constant, z1 is the compressibility, m is the molar flow rate,
	a = (k-1)/k , and k = Cp/Cv
D. The outlet for the adiabatic reversible flow, T2 = T1 (P2 / P1)a
E. Exit temperatures should not exceed 204 0C (400 0F).
F. For diatomic gases (Cp/Cv = 1.4) this corresponds to a compression ratio of about 4
G. Compression ratios should be about the same in each stage for a multistage unit,
the ratio = (Pn / P1) 1/n, with n stages.
H. Efficiencies for reciprocating compressors are as follows:
	65% at compression ratios of 1.5
	75% at compression ratios of 2.0
	80-85% at compression ratios between 3 and 6
I. Efficiencies of large centrifugal compressors handling 2.8 to 47 m3/s (6000-100,000 acfm) at suction is about 76-78%
J. Reciprocating piston vacuum pumps are generally capable of vacuum to 1 torr absolute, rotary piston types can achieve vacuums of 0.001 torr.
K. Single stage jet ejectors are capable of vacuums to 100 torr absolute, two stage to 10 torr, three stage to 1 torr, and five stage to 0.05 torr.
L. A three stage ejector requires about 100 lb steam/lb air to maintain a pressure of 1 torr.
M. Air leakage into vacuum equipment can be approximated as follows: Leakage = k V(2/3) where k =0.20 for P >90 torr, 0.08 for 3 < P < 20 torr, and 0.025 for P < 1 torr V = equipment volume in cubic feet Leakage = air leakage into equipment in lb/h

Heat Exchangers
A.     For the heat exchanger equation, Q = UAF (LMTD), use F = 0.9 when charts for the LMTD Correction factor are not available
B.     Most commonly used tubes are 3/4 in. (1.9 cm) in outer diameter on a 1 in triangular spacing at 16 ft (4.9 m) long.
C. A 1 ft (30 cm) shell will contains about 100 ft2 (9.3 m2)
A 2 ft (60 cm) shell will contain about 400 ft2 (37.2 m2)
A 3 ft (90 cm) shell will contain about 1100 ft2 (102 m2)
C.     Typical velocities in the tubes should be 3-10 ft/s (1-3 m/s) for liquids and30-100 ft/s (9-30 m/s) for gases
E. Flows that are corrosive, fouling, scaling, or under high pressure are usually placed in the tubes
F. Viscous and condensing fluids are typically placed on the shell side.
G. Pressure drops are about 1.5 psi (0.1 bar) for vaporization and 3-10 psi (0.2-0.68 bar) for other services
H. The minimum approach temperature for shell and tube exchangers is about 20 °F (10 °C) for fluids and 10 °F (5 °C) for refrigerants.
I.        Cooling tower water is typically available at a maximum temperature of 90 °F (30 °C) and should be returned to the tower no higher than 115 °F (45 °C)
J.       Shell and Tube heat transfer coefficient for estimation purposes can be found in many reference Books or an online list can be found at one of the two following addresses:
	http://www.cheresources.com/uexchangers.shtml
	http://www.processassociates.com/process/heat/uvalues1.htm
K. Double pipe heat exchangers may be a good choice for areas from 100 to 200 ft2 (9.3-18.6 m2)
L. Spiral heat exchangers are often used to slurry interchangers and other services containing solids
M. Plate heat exchanger with gaskets can be used up to 320 °F (160 °C) and are often used for Interchanging duties due to their high efficiencies and ability to "cross" temperatures. More about compact heat exchangers can be found at:
	http://www.us.thermal.alfalaval.com/

Tray Towers
A. For ideal mixtures, relative volatility can be taken as the ratio of pure component vapor pressures
B. Tower operating pressure is most often determined by the cooling medium in condenser or the maximum allowable reboiler temperature to avoid degradation of the process fluid
C. For sequencing columns:
	1. Perform the easiest separation first (least trays and lowest reflux)
	2. If relative volatility nor feed composition vary widely, take products off one at time as the overhead
	3. If the relative volatility of components do vary significantly, remove products in order
	of decreasing volatility
	4. If the concentrations of the feed vary significantly but the relative volatility do not,
	remove products in order of decreasing concentration.
D. The most economic reflux ratio usually is between 1.2Rmin and 1.5Rmin
E. The most economic number of trays is usually about twice the minimum number of trays.The minimum number of trays is determined with the Fenske-Underwood Equation.
F. Typically, 10% more trays than are calculated are specified for a tower.
G. Tray spacings should be from 18 to 24 inches, with accessibility in mind
H. Peak tray efficiencies usually occur at linear vapor velocities of 2 ft/s (0.6 m/s) at moderate pressures, or 6 ft/s (1.8 m/s) under vacuum conditions.
I. A typical pressure drop per tray is 0.1 psi (0.007 bar)
J. Tray efficiencies for aqueous solutions are usually in the range of 60-90% while gas absorption and stripping typically have efficiencies closer to 10-20%
K. The three most common types of trays are valve, sieve, and bubble cap. Bubble cap trays are
typically used when low-turn down is expected or a lower pressure drop than the valve or sieve
trays can provide is necessary.
L. Seive tray holes are 0.25 to 0.50 in. diameter with the total hole area being about 10% of the total active tray area.
M. Valve trays typically have 1.5 in. diameter holes each with a lifting cap. 12-14 caps/square foot of tray is a good benchmark. Valve trays usually cost less than seive trays.
N. The most common weir heights are 2 and 3 in and the weir length is typically 75% of the tray diameter
O. Reflux pumps should be at least 25% overdesigned
P. The optimum Kremser absorption factor is usually in the range of 1.25 to 2.00
Q. Reflux drums are almost always horizontally mounted and designed for a 5 min holdup at half of the drum's capacity.
R. For towers that are at least 3 ft (0.9 m) is diameter, 4 ft (1.2 m) should be added to the top for vapor release and 6 ft (1.8 m) should be added to the bottom to account for the liquid level and reboiler return
S. Limit tower heights to 175 ft (53 m) due to wind load and foundation considerations.
T. The Length/Diameter ratio of a tower should be no more than 30 and preferrably below 20
U. A rough estimate of reboiler duty as a function of tower diameter is given by:
	Q = 0.5 D2 for pressure distillation
	Q = 0.3 D2 for atmospheric distillation
	Q = 0.15 D2 for vacuum distillation
	where Q is in Million Btu/hr and D is tower diameter in feet

Packed Towers
A. Packed towers almost always have lower pressure drop than comparable tray towers.
B. Packing is often retrofitted into existing tray towers to increase capacity or separation.
C. For gas flowrates of 500 ft3/min (14.2 m3/min) use 1 in (2.5 cm) packing, for gas flows
of 2000 ft3/min (56.6 m3/min) or more, use 2 in (5 cm) packing
D. Ratio of tower diameter to packing diameter should usually be at least 15
E. Due to the possibility of deformation, plastic packing should be limited to an unsupported
depth of 10-15 ft (3-4 m) while metallatic packing can withstand 20-25 ft (6-7.6 m)
F. Liquid distributor should be placed every 5-10 tower diameters (along the length) for pall rings and every 20 ft (6.5 m) for other types of random packings
G. For redistribution, there should be 8-12 streams per sq. foot of tower area for tower larger than three feet in diameter. They should be even more numerous in smaller towers.
H. Packed columns should operate near 70% flooding.
I. Height Equivalent to Theoretical Stage (HETS) for vapor-liquid contacting is 1.3-1.8 ft
(0.4-0.56 m) for 1 in pall rings and 2.5-3.0 ft (0.76-0.90 m) for 2 in pall rings
J. Design pressure drops should be as follows:
	Service				Pressure drop (in water/ft packing)
	Absorbers and Regenerators
		Non-Foaming Systems			0.25 - 0.40
		Moderate Foaming Systems			0.15 - 0.25
	Fume Scrubbers
		Water Absorbent			0.40 - 0.60
		Chemical Absorbent			0.25 - 0.40
	Atmospheric or Pressure Distillation				0.40 - 0.80
	Vacuum Distillation				0.15 - 0.40
	Maximum for Any System				1.0
**For packing factors and more on packed column design see:

Reactors
A. The rate of reaction must be established in the laboratory and the residence time or space velocity will eventually have to be determined in a pilot plant.
B. Catalyst particle sizes: 0.10 mm for fluidized beds, 1 mm in slurry beds, and 2-5 mm in fixed beds.
C. For homogeneous stirred tank reactions, the agitor power input should be about
0.5-1.5 hp/1000 gal (0.1-0.3 kW/m3), however, if heat is to be transferred, the agitation should
be about three times these amounts.
D. Ideal CSTR behavior is usually reached when the mean residence time is 5-10 times the length
needed to achieve homogeneity. Homogeneity is typically reached with 500-2000 revolutions
of a properly designed stirrer.
E. Relatively slow reactions between liquids or slurries are usually conducted most
economically in a battery of 3-5 CSTR's in series.
F. Tubular flow reactors are typically used for high productions rates and when the residence
times are short. Tubular reactors are also a good choice when significant heat transfer to or from
the reactor is necessary.
G. For conversion under 95% of equilibrium, the reaction performance of a 5 stages CSTR
approaches that of a plug flow reactor.
H. Typically the chemical reaction rate will double for a 18 °F (10 °C) increase in temperature.
I. The reaction rate in a heterogeneous reaction is often controlled more by the rate of heat or
mass transfer than by chemical kinetics.
J. Sometimes, catalysts usefulness is in improving selectivity rather than increasing the rate of rn.

Refrigeration and Utilities
A. A ton of refrigeration equals the removal of 12,000 Btu/h (12,700 kJ/h) of heat
B. For various refrigeration temperatures, the following are common refrigerants:
	Temp (°F)	Temp (°C)	Refrigerant
	0 to 50	-18 to -10	Chilled brine or glycol
	-50 to -40	-45 to -10	Ammonia, freon, butane
	-150 to -50	-100 to -45	Ethane, propane
C. Cooling tower water is received from the tower between 80-90 °F (27-32 °C) and should be
returned between 115-125 °F (45-52 °C) depending on the size of the tower.
Seawater should be return no higher than 110 °F (43 °C)
D. Heat transfer fluids used: petroleum oils below 600 °F (315 °C), Dowtherms or other
synthetics below 750 °F (400 °C), molten salts below 1100 °F (600 °C)
E. Common compressed air pressures are: 45, 150, 300, and 450 psig
F. Instrument air is generally delivered around 45 psig with a dewpoint 30 °F below the coldest expected ambient temperature.