Transport of Solids, Liquids, and Gases Flashcards
Transporting Solids - Conveyor Belt & Pneumatic Conveyor
raw and intermediate streams over relatively short distances, within plant boundaries or to storage yards, sheds, facilities
Transporting Solids - Trucks
raw, intermediate & finished products over short to medium distances outside the premises of processing plants or storage depots
Transporting Solids - Railways
intermediate & finished products over medium to large distances to storage depots
Transporting Solids - Ships & Barges
intermediate & finished products over medium to large overseas destinations
Transporting Liquids & Gases - Trucks
intermediate & finished streams over relatively short or medium distances
Transporting Liquids - Railways
intermediate & finished products over long distances (AB, SK to BC, TX)
Pipelines (liquids, slurries, gases)
intermediate & finished products over relatively long distances
Transporting Liquids & Gases - Ships
raw materials & finished products over medium to large distances/destinations (across oceans). For example, crude oil & CNG/LNG
Flowlines
connect and move raw products (oil & gas) from wellheads to the inlet of gathering pipelines
Gathering pipelines
move raw products from Flowlines to processing plants or storage tanks
Feeder pipelines
move raw products, crude oil, natural gas and NGLs from processing plants and storage tanks to transmission pipelines
Transmission pipelines
transport crude oil, natural gas, NGLs and refined products across provinces/states and countries
Distribution pipelines
made up of ‘main’ and ‘service’ lines, deliver natural gas to homes and businesses
Pipes
-Used to transport liquids, gases, slurries, powders,
small particles (as in pneumatic conveying)
-Can be ‘seamed’ or ‘seamless
How are pipes specified
a nominal pipe size (NPS) and a Schedule Number that defines their wall thickness
-NPS does not match the actual pipe ID or OD.
-Schedule Numbers are 5, 10, 40, 80, 120 & 160 (A higher Schedule Number implies a thicker pipe wall)
What are pipes made out of
carbon steel, stainless steels, concrete, ceramics, plastics, etc
Tubes (usually small diameter)
Tubes are specified by their actual outside diameter, whereas the Gauge Number defines their wall thickness
-Tubes are generally ‘seamless’.
-Gauge Numbers can vary from 7 to 22.
* A higher Gauge Number implies a thinner pipe wall.
What are tubes made out of
stainless steels, copper, aluminum, alloys, polymers, plastics, rubber, glass
Barlow’s formula
-internal pressure at minimum yield
-ultimate burst pressure
-maximum allowable pressure
Py (internal pressure at min yield) = 2Sy (yield strength) t (wall thickenss) /do (outside diameter)
Gate valve
mainly for on/off control, with low pressure drop
Globe valve
good for regulating flow, uses a cylinder movement over a seat
Ball valve
for on/off control with low pressure drop, for quick shut‐off (a 90° turn for shut‐off)
Needle valve
used for accurate flow control
Butterfly valve
for on/off flow control in large diameter pipes.
Diaphragm valve
controls flow by movement of a diaphragm. Used in pharmaceutical applications
Plug valve
a slim valve for on/off control
Solenoid valve
an electrically actuated valve for hydraulic, pneumatic or electrical fluid control
3‐Way valve
for redirecting the flow
Parts of a Globe Valve (pg 16 slides)
- body; 2. ports;
- seat; 4. stem;
- disc (when open);
- handle (when open);
- bonnet; 8. packing;
- gland nut;
- fluid flow (when open);
- Disc position (when shut);
- Handle position (when
shut)
Fittings are used to connect
-straight sections of pipes or tubes,
-change to different pipe sizes, and
-for manipulating the flow direction.
Most common types of fittings
elbows, tees, wyes (or ‘Y’s), crosses, couplings, unions, reducers, caps, plugs
Connection or joining methods
threading, welding, solvent welding, soldering, brazing, compression, flare, flange, mechanical sleeve, crimped or pressed
Elbows
Also known as “ells,” these are used to change the direction of flow by 45o or 90.
Tees, Ys, Crosses
Used to combine or split pipe or tube sections; tees and Ys have one input and two outputs (or vice versa); crosses have one input and
three outputs (or vice versa)
Couplings, Unions, Reducers
Used to connect two straight pieces of pipe or tubing
Compression fittings
Used to pressure‐tighten connections, better at preventing leakage
Caps, Plugs
Used for creating a dead end (which might be opened or used later on).
Pumps
“moving” fluids (liquids, gases, slurries, pastes, etc) by “converting” energy (electrical, mechanical, chemical, etc) into “work”
that translates into an increased pressure head
-In (simple) pumps, the pressure of outlet stream is
higher than the atmospheric pressure.
Vacuum pumps
pressure of inlet stream is lower than the atmospheric pressure
Priming a Pump
A liquid pump cannot draw air; hence, the feed line and the pump itself must be filled with the liquid before initiating the pumping.
This is especially important for centrifugal pumps
Net Positive Suction Head or NPSH
for pumps is the difference between the pressure at pump suction
and the liquid vapor pressure.
Importance of NPSH
The NPSH must be POSITIVE for proper pump performance and to eliminate the risk of cavitation (the generation of vapour bubbles
in a liquid), which can also damage the pump)
Pumps – Power Requirement
P (input power) = pgHQ/n
n= pump efficiency (less than 1)
H = energy head to fluid (m)
Positive displacement pump
a constant amount of inlet stream is trapped and forced (displaced) as the outlet stream
Centrifugal pump
converts rotational kinetic energy to the hydrodynamic (pressure) energy; the flow direction changes by 90o as the fluid flows
radially outward over the impeller
Axial‐flow pump
similar in principle to the centrifugal pump, but the flow direction is unchanged.
Which pumps provide constant flow?
-Positive displacement pumps produce the same flow rate, at a given speed, regardless of the discharge pressure
-positive displacement pumps provide constant flow (except for a slight internal leakage).
Safety in positive displacement pumps
a relief or safety valve on the discharge side is provided (which may allow the discharge back to the suction line or supply tank)
-They must not be operated with a closed discharge valve to avoid an excessive discharge pressure that can cause pipe bursts and/or severe pump damage
Rotary type positive displacement
(Gear, Screw, Peristaltic, etc): Moves the fluid using
a rotating mechanism to create a vacuum that captures and
draws in the liquid.
Reciprocating type positive displacement
(Piston, Diaphragm, etc): reciprocating motion pushes the fluid through (with the help of valves); usually more than one in parallel for uniform discharge rate, Duplex, Triplex,
Linear type positive displacement
(Rope, Chain,etc): Like a vertical conveyor belt, with holding cups
Centrifugal Pumps - Details
These convert rotational energy, to a moving fluid, from an electrical motor, to energy in the form of kinetic energy and hydrostatic (or pressure) head.
-The fluid gains both velocity and pressure while passing through the impeller
Diffuser section - Centrifugal Pump
The diffuser section of the casing decelerates the flow and further increases the pressure.
Where does the fluid enter and exit, centrifugal pump
The fluid enters axially into the casing, is pushed
tangentially and radially outward, and leaves
through the circumferential part of the impeller into
the casing.
Axial‐Flow Pumps
-Axial‐flow pumps essentially consist of a marine
propeller (an axial impeller) placed in a pipe.
-The propeller can be driven directly by a sealed
motor in the pipe or from the outside via by a drive
shaft that goes through the pipe.
-These pumps are small in size compared to other
pumps.
-These are more suited for low discharge pressure
and high flow rates.
Vacuum Pumps ‐ Ejectors
-Ejectors use steam pressure to draw water vapour
(and air) from a vessel, or a unit operation, under vacuum on a continuous basis, such as in evaporators, crystallizers, etc
Vacuum Pumps - suction pressure less than 10 kPa
For suction pressures less than 10 kPa, more than one ejector is used, usually with condensers in between 2 or more ejector stages.
-Condensation of steam greatly improves the ejector
efficiency (by decreasing the flow rate); direct contact barometric condensers are used commonly
Three stage vacuum system
can consist of a primary booster, a secondary high‐vacuum (HV) ejector, and a tertiary low vacuum (LV) ejector
Blower and Fans
-pushing a large volume of gases at lower pressures
-They use the centrifugal power supplied from the rotation of impellers to increase the kinetic energy of gases
Typical pressure ratio (discharge to suction) and pressure increase for fans and blowers
-Fans: 1.0 < Pressure ratio < 1.1
0 kPa < Pressure increase < 10 kPa
-Blowers: 1.1 < Pressure ratio < 1.2
10 kPa < Pressure increase < 20 kPa
Compressors
increase the pressure of compressible fluids, specifically (only) gases.
Industrial Applications of Compressors
Truck and Vehicle‐mounted compressors
* Medical and Hospital applications
* Laboratory and specialty gas compression
* Food, Beverage, Refrigeration applications
* Fertilizers, Polymers, Power plants, etc
* Oil & Gas applications, including Pipelines
* CCUS (carbon capture utilization & storage)
Most common compressor, most common pump
Whereas pumps are predominately the centrifugal types, compressors are more commonly the positive displacement type.
Three main parameters to consider- compressors
-Volumetric Capacity: Rate of gas delivered per unit time (typically as scfm @ 100 kPa and 20°C)
-Pressure capability: Largely based on the need. From single‐stage for lower pressures to multi‐stage for higher pressures.
-Power: Depends on the volumetric flow and pressure change considerations. Also consider efficiency, losses, belt‐ or direct‐driven motor, gas‐ or diesel‐engine, etc
-Other factors are: type of gas (flammable or corrosive?), controls, and capital & operating costs.
Two main types of compressors
- Positive Displacement:
-Rotary (Screw, Lobe, Scroll, Vane, etc)
-Reciprocating (Diaphragm, Piston – Single &
Double Acting, etc) - Dynamic:
-Centrifugal
-Axial
Rotary Positive Displacement Compressors - Screw
Uses male and female geared rotors.
Rotary Positive Displacement Compressors - Lobe
high‐volume & low‐pressure. Closer to blowers.
Rotary Positive Displacement Compressors - Scroll
Uses stationary and orbiting spirals. Intake at the outer edge of scrolls and discharge at the centre.
Rotary Positive Displacement Compressors - Vane
Uses a series of vanes, mounted in a rotor, which sweep along the inside wall of an eccentric cavity.
Reciprocating Positive Displacement Compressors - Diaphragm
uses a concentric motor that oscillates a flexible disc, alternatingly expanding and contracting the compression chamber.
Reciprocating Positive Displacement Compressors - Piston
Relies on the reciprocating action of piston(s)
to compress gas within a cylinder(s).
Single Acting: The gas acts only on one side of
the piston.
Double Acting: The gas acts on both sides of
the piston.
Dynamic Compressors - Centrifugal Compressors
use high‐speed impellers to impart velocity to produce an increase in pressure. Lower compression ratios than positive displacement types, but handle vast gas volumes.
Dynamic Compressors - Axial Compressors
increase pressure by increasing the velocity of the gas then slow the gas down by passing it through curved, fixed blades, which increases its pressure
