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CONVENTIONS |
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Throughout this
article, the terms
- Propane, Butane, LPG, and LP are
used interchangeably;
- NatGas (or NatGas) is abbreviated as NG or
NatGas;
- LP/Air, LPG/Air, Propane/Air, mixed
gas, and
Synthetic NatGas are used interchangeably;
- SNG is the abbreviation for
Synthetic NatGas;
- Mixer and Blender are used
interchangeably.
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INTRODUCTION |
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Alternate
Energy Systems, Inc. manufactures LPG Vaporizers, LPG Vapor
/ Air Mixers (Blenders), and complete Systems for use as
standby plant, for peak shaving, and as primary gas supply.
Since the company was founded in 1974, we have manufactured
a wide variety of individual components and packaged
systems. These components and packages, complete with
interconnecting piping, wiring, and control and monitoring
equipment, are thoroughly factory tested, and are ready for
connection to liquid LPG supply, properly sized electrical
supply, and mixed gas outlet.
In
addition to LP and LP/Air Systems, AES also manufactures
gas/gas blenders for applications such as NatGas
Stabilization; Landfill Gas Replacement/Backup; Digester Gas
Replacement and Enrichment; Coke Gas Replacement/Backup;
Air/Nitrogen Blending; etc.
Alternate
Energy Systems (AES) is a company operated by dedicated
people.
People with a vast knowledge of the industry. People who are
aware of energy problems - and know how to solve them. Every
member of AES has been closely involved with the energy
industry in the past and continues to offer a more valid and
precise solution for your energy needs now and in the
future.
All equipment
manufactured by Alternate Energy Systems is available in
various sizes and configurations, and with various options.
Please consult with your area distributor or the factory for
your specific requirements. |
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WHAT IS
A LPG STANDBY PLANT? |
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A "standby
plant" - as the term implies, is something standing by to do a job. A
Propane standby
plant, offered to industrial and utility users of NatGas, is a system that is an
alternate source of energy in the event the NatGas source becomes
unavailable (because of curtailment, maintenance shutdown, or
catastrophic failure).
While some facilities use oil as a standby
fuel, oil is not a direct replacement for NatGas and will not burn in NatGas
burners or equipment. Thus, oil requires a separate set of burners, controls and
piping (which increases the equipment cost).
Propane or LPG is an ideal standby fuel for
NatGas. Propane, when mixed with air, will duplicate the burning
characteristics of NatGas and allows the user to utilize existing NatGas
burners, piping and controls. There is generally no need to change the setup
of the combustion equipment when the fuel supply changes from NatGas to
LP/air, or from LP/air to NatGas.
A standby system generally consists of:
- LPG STORAGE TANK(s);
- A PUMP to transfer LPG to the Vaporizer;
- A VAPORIZER to convert the liquid LPG to a gas;
- A MIXER or BLENDER to mix the vaporized
LPG with air.
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WHY USE A
STANDBY SYSTEM? |
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While there are many
reasons a standby system is used, the principal reason is insurance against interruption
of normal NatGas supply. Another incentive is that many utility companies offer what
is known as an "interruptible rate" to industrial customers.
First - interruption of
NatGas?
Many are not aware that
NatGas
utilities (local distribution companies [LDC]) purchase or contract from a pipeline, a certain amount of
NatGas
transportation capacity for a
certain period. The contracted capacity has to be sufficient to supply all
"firm gas" customers (both residential and industrial) on the coldest day
of the year.
By definition, this means that the contracted transportation capacity is
under-utilized during the other 364 days in a year.
To better utilize the contracted transportation capacity, LDCs like to add large gas users as
"interruptible" load. If the pipeline capacity that is normally occupied
by the interruptible customers is needed to supply gas to "firm"
customers, the LDCs ask their interruptible customers to stop using
NatGas and to switch to their LP/Air standby system.
As an incentive for these
interruptible customers to install a standby system, the LDCs
offer steep discounts on the price of NatGas. The savings are available
year-round, regardless whether or not the NatGas is ever curtailed.
Since the "interruptible rate" is enjoyed every
day of the year, not just during cold months when gas is most critical, it is possible to
amortize the cost of a standby facility, including the installation, over a very short
period of time, usually in less than two years, in some cases in as little
as 6 months..
With a useful life of a
standby system of 15-25+ years, this means that significant energy cost
savings are being realized by the owner of the standby system
year-after-year, with only upkeep and maintenance as recurring expenses.
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WHAT
IS A PEAKLOAD SHAVING PLANT? |
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Peakload
Shaving is a term used by utility companies. As stated before, LDCs purchase a
certain amount of gas over a fixed period of time. The best laid plans cannot take into
consideration unexpected cold spells, a burst pipeline, or other events that could happen to
disrupt the planned quota.
If the LDC should need more gas than it has contracted,
they pay a premium price if the gas is available, to begin with. So, to insure
extra gas and avoid premium price for gas above the contracted amount, many utility
companies use LP, blended with air, to duplicate the properties of NatGas. This
blended gas is then used to supplement the LDC's gas supply, allowing a more consistent
fuel flow rate from their supplier and help meet peak demand loads. (PeakShaving
System Web Page)
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WHO USES A STANDBY PLANT? |
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Utilities and municipalities;
ceramics product manufacturers;
glass plants; bakeries; metal processing firms; textile industries; chemical companies; or,
any industrial company that uses large amounts of NatGas in any of its processes. |
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WHAT IS
LP-GAS? |
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LP-Gas or LPG is the
abbreviation for liquefied petroleum gas, with the most commonly known being
Propane and
Butane. At normal atmospheric pressure and temperatures, LP-Gas is in the gaseous state.
However, it is converted to the liquid state with moderate pressure. This is why LPG is
transported and stored in tanks or containers having at least 250 psi working pressure.
The main source of LPG is
NatGas and crude oil
mixtures as they come from active oil and NatGas wells. Though Propane is similar to
NatGas (Methane), Propane has 2516 BTU per cubic foot (22390 kcal/m³), compared to 1020 BTU per
cubic foot (9005 kcal/m³) for NatGas. That is why Propane, when mixed in proper proportion with air,
is an excellent supplement or replacement to NatGas.
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Properties of |
Natural Gas |
Propane |
Butane |
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Chemical formula |
|
CH4 |
C3H8 |
C4H10 |
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Boiling point of liquid at atmospheric pressure |
°F
°C |
-259
-162 |
-44
-42 |
32
0 |
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Specific Gravity of vapor (Air = 1) |
|
0.6 |
1.53 |
2.00 |
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Specific Gravity of liquid (Water = 1) |
|
|
0.51 |
0.58 |
|
Calorific value @ 60 °F (15°C) |
BTU/cuft
kcal/m3 |
1012
9005 |
2516
22,390 |
3280
29,190 |
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BTU/gal
kcal/liter |
|
91,690
6,100 |
102,032
6,790 |
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BTU/lb
kcal/kg |
|
21,591
11,995 |
21,221
11,790 |
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Latent heat of vaporization |
BTU/gal
kcal/kg |
|
785
103 |
808
93 |
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Liquid weight |
lbs/gal
kg/liter |
|
4.24
0.508 |
4.81
0.576 |
Vapor volume from 1 gallon of liquid at 60 °F
Vapor volume from 1 liter of liquid at 15 °C |
cuft
m3 |
|
36.39
0.272 |
31.26
0.234 |
Vapor volume from 1 lb. of liquid at 60 °F
Vapor volume from 1 kg of liquid at 15 °C |
cuft
m3 |
|
8.547
0.534 |
6.506
0.406 |
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Combustible limits |
% of gas in air |
5 - 15 |
2.4 - 9.6 |
1.9 - 8.6 |
Amount of air required to burn 1 cuft. of gas
Amount of air required to burn 1 m3 of gas |
cuft
m3 |
9.53 |
23.86 |
31.02 |
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Ignition temperature in air |
°F
°C |
1200
650 |
920 - 1020
490 - 550 |
900 - 1000
480 - 540 |
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Maximum flame temperature in air |
°F
°C |
3568
1964 |
3595
1980 |
3615
1991 |
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Octane Number |
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100 |
Over 100 |
92 |
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All data is approximate. For actual properties of
any particular batch, contact your fuel supplier. |
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Approximate
Vapor Pressure in psig
Approximate
Vapor Pressure in bar |
|
Temperature |
Propane
----> To
----> Butane |
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° F |
° C |
100% |
95/5* |
80/20 |
60/40 |
50/50 |
40/60 |
20/80 |
100% |
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-40 |
-40.0 |
3.6
0.248 |
1.3
0.090 |
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-30 |
-34.4 |
8
0.552 |
5.5
0.379 |
4.5
0.310 |
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-20 |
-28.9 |
14
0.965 |
11
0.758 |
9.2
0.634 |
4.9
0.338 |
1.9
0.131 |
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-10 |
-23.3 |
20
1.38 |
17
1.17 |
16
1.10 |
9
0.621 |
6
0.414 |
3.5
0.241 |
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0 |
-17.8 |
28
1.93 |
24
1.66 |
22
1.52 |
15
1.03 |
11
0.758 |
7.3
0.503 |
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10 |
-12.2 |
37
2.55 |
32
2.21 |
29
2.00 |
20
1.38 |
17
1.17 |
13
0.896 |
3.4
0.234 |
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|
20 |
-6.7 |
47
3.24 |
41
2.83 |
36
2.48 |
28
1.93 |
23
1.59 |
18
1.24 |
7.4
0.510 |
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30 |
-1.1 |
58
4.00 |
52
3.59 |
45
3.10 |
35
2.41 |
29
2.00 |
24
1.66 |
13
0.896 |
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|
40 |
4.4 |
72
4.96 |
63
4.34 |
58
4.00 |
44
3.03 |
37
2.55 |
32
2.21 |
18
1.24 |
3
0.207 |
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50 |
10.0 |
86
5.93 |
77
5.31 |
69
4.76 |
53
3.65 |
46
3.17 |
40
2.76 |
24
1.66 |
6.9
0.476 |
|
60 |
15.6 |
102
7.03 |
93
6.41 |
80
5.52 |
65
4.48 |
56
3.86 |
49
3.38 |
30
2.07 |
12
0.827 |
|
70 |
21.1 |
127
8.76 |
109
7.52 |
95
6.55 |
78
5.38 |
68
4.68 |
59
4.07 |
38
2.62 |
17
1.17 |
|
80 |
26.7 |
140
9.65 |
128
8.83 |
125
8.62 |
90
6.21 |
80
5.52 |
70
4.83 |
46
3.17 |
23
1.59 |
|
90 |
32.2 |
165
11.4 |
149
10.3 |
140
9.65 |
112
7.72 |
95
6.55 |
82
5.65 |
56
3.86 |
29
2.00 |
|
100 |
37.8 |
196
13.5 |
172
11.9 |
168
11.6 |
137
9.45 |
123
8.48 |
100
6.90 |
69
4.76 |
36
2.48 |
|
110 |
43.3 |
220
15.2 |
197
13.6 |
185
12.8 |
165
11.4 |
148
10.2 |
130
8.96 |
80
5.52 |
45
3.10 |
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* HD5, Commercial Grade Propane
All data is approximate.
For actual properties of
any particular batch, contact your fuel supplier. |
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WHAT IS A
LPG VAPORIZER? |
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As shown
above,
LPG (Propane, Butane, or Propane/Butane Mixture) at ambient pressure
(above its boiling point temperature) is a gas that is stored in
pressurized containers (tanks) in liquid form. The space in the tank
that is not filled with liquid is occupied by vapor. As this vapor is
being used as fuel for connected equipment (burners, heaters, etc.),
liquid LPG must vaporize (change its state from liquid to gas) to occupy
the space above the liquid.
Any time a
change of state occurs, energy is required. If the ambient temperature
is above the boiling point of the LPG (Propane -44°F / -42°C; Butane
32°F / 0°C at ambient pressure; see
chart above for the boiling
temperature of LPG at various pressures), this energy is transferred in
the form of heat from the ambient air through the steel walls of the
storage tank, into the LPG. As the heat is transferred from the ambient
air to the vaporization process, the ambient air "looses" this energy
and cools down.
The amount of
heat that is transferred into the LPG determines the rate of
vaporization. As the ambient air cools down, the rate of vaporization
slows down, and stops completely when the ambient air is at the same
temperature as the boiling point of the LPG. Therefore, naturally
occurring vaporization cannot be used for large gas loads, or in low
ambient temperatures.
A vaporizer is
designed to receive the liquid LPG and raise its temperature (heat the
liquid) well above the boiling point at the delivery pressure. In other
words, a vaporizer generates the (heat)energy that is required to
maintain the gaseous state of the LPG.
The heat required to change the
state of the LP from liquid to gaseous is also called the latent heat of
vaporization. Typical LPG requires a heat input of approximately 800 BTU
to vaporize 1 gallon of liquid (approximately 100 kcal per kg of
liquid). AES vaporizers are designed to generate approximately 1.5 times
the latent heat of vaporization. The excess heat is carried by the LP
vapor as superheat. Superheat is required to maintain the gaseous state
of the LP downstream of the vaporizer.
There are two major types of LPG vaporizers: Vaporizers that supply a
small portion of the
vaporized LPG as fuel for the burner that supplies the heat for the vaporization process
(i.e. Water Bath Vaporizers); and vaporizers that use an outside source of heat, such as steam or hot water, to vaporize
the LPG. |
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WHAT ARE MIXERS AND BLENDERS? |
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After the
liquid Propane has been vaporized, it needs to be blended in proper proportion with air to
duplicate the characteristics of NatGas. This is where mixers and blenders come in.
There are several methods to mix air and
LPG vapor. Probably the most simple method is to use a venturi tube and a nozzle. This
method, as well as other methods, holds very accurate air-to-fuel ratios through a narrow
range. This type mixer does not generally require compressed air for operation. However,
the maximum achievable system pressure is somewhat limited. The mixture of air and vapor
is fed into a surge tank, where it is maintained at a set pressure, and then drawn from
the surge tank for use. This type system is usually recommended for intermittent periods
of use and is very simple to operate.
Blenders and modulating proportioning
mixers are usually more complex, but are usually also more accurate than
Venturi-type mixers. They are also capable of blending LP vapor with air in
much larger
volumes at much higher pressure. These systems are recommended for continuous or long periods of
usage, and are ideally suited for PeakShaving and larger installations.
Regardless of the type vaporizer and
blender, a standby
system can be designed for the requirements of small users, or the requirements of large
industrial and utility users. In times of uncertain oil prices and supplies, a
standby system should be considered by all Natural Gas users. Just like we keep a spare
tire for our automobile in the event of a flat, a standby system is a spare fuel supply in
the event Natural Gas is interrupted or demand cannot be met.
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ALTERNATE
ENERGY SYSTEMS' VAPORIZERS |
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Alternate Energy Systems manufactures LPG vaporizers with capacities from
168 gallons per hour (322 kg/h)
to 14000 gph (28000 kg/h). To meet the requirements of customers and particular applications around the world, we are employing
a variety of design concepts and configurations. Their heat source can be hot water (Water Bath Vaporizers; Circulating Hot-Water
Vaporizer) or steam (Steam Vaporizers). All vaporizers are manufactured to the rigid codes of the American Society of Mechanical
Engineers (ASME), the latest edition of NFPA #58 and/or #59, and most are approved for Factory Mutual (FM) or
Industrial Risk Insurers (IRI) installations, in addition to approvals by Canadian Standards Association (CSA),
American Gas Association (AGA), and Canadian Gas Association (CGA). Most
vaporizers are also available with the European CE Mark.
As a manufacturer, we go far beyond the requirements and
codes and are continually working to produce equipment with the most modern engineering techniques available.
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WATER BATH
VAPORIZERS WB-xxxx series |
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AES manufactures two
lines of Water Bath Vaporizers, the 08-Series for capacities from 168
gph to 508 gph (322 kg/h to 975 kg/h), and the 05-Series for capacities
from 455 gph to 10005 gph (873 kg/h to 20 metric tons per hour).
All AES water bath
vaporizers are of "horizontal" design. Top and sides are insulated to
hold the temperature of the water bath. The vaporizing tube bundle and
all LPG piping conform to the standards of the ASME Boiler and Pressure
Vessel Code and the latest edition of NFPA Pamphlet #58. The design is
approved by Factory Mutual (FM) and Canadian Standards Association
(CSA), and is accepted for Industrial Risk Insurers (IRI) installations.
The vaporizers are also available with European CE Approval (third-party
inspection by TÜV Rheinland and TÜV Süd).
A mixture of water and
antifreeze is the heat transfer medium. A pump constantly circulates the
solution to reduce heat stratification. The vaporizers are skid mounted,
factory tested, primed, painted and ready for installation. They are
ready for connection to properly sized electrical supply, liquid propane
inlet and vapor outlet.
The vaporizers come with
2 sets of Operating Manuals and Test Reports, are designed for outdoor
installation, and require only nominal preventive maintenance.
The model number (WB-xxxx)
designates the vaporization capacity in gallons per hour Propane
vaporization at 0°F (-18°C) inlet temperature.
All WB vaporizers are
manufactured with a protective enclosure for the burner and the control
components. Models WB-1805 and above are equipped with an extended
control room (maintenance house), which is available as an option for
the smaller models WB-455 to WB-1505.
Model numbers ending in
"8" utilize a European-style compact power burner; model numbers ending
in "5" utilize Maxon TOT burners (or similar types). Both series are
equipped with an Agency-approved Safety Controller and and with an
electronic flame safe guard (Honeywell 7800 series). This combination
elevates the safety of the vaporizers to "Performance Level 4" (formerly
known as SIL 3). Both series of vaporizers are equipped with "Smart"
Liquid Carryover Protection function by a Rosemount pressure transmitter
and a Rosemount temperature transmitter in the vapor outlet.
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08-Series: MODEL WB-168 THRU WB-508
These models are manufactured with a
European-style, high-efficiency compact power burner. All vaporizer
functions are constantly monitored by a Programmable Logic
Controller with Ethernet interface (PLC; Siemens S7-1200 or
Allen-Bradley MicroLogix-1100), which communicates with a graphic
display operator interface (color LCD display with touch screen).
The operator interface is used to monitor and display the system
status; any failure message will be displayed in plain English;
first-outage-monitor (Alarm History) and graphic trend recording are
standard. The PLC is installed together with the Honeywell Satronic
flame control module in the control panel, which is mounted in the
vaporizer control room. The full-size step-in control room is
equipped with country-specific receptacles and light fixture.
The vaporizers are
equipped with a “smart” liquid carryover protection. Vapor pressure
and temperature are constantly monitored by a dedicated Rosemount
pressure transmitter and a Rosemount temperature transmitter. Their
signals are processed in the PLC and are compared against the vapor
pressure/ temperature saturation curve of the LPG that is being
vaporized. The properties of the LPG (Propane/Butane percentage),
and the “safety margin” (how close the pressure/temperature are
allowed to come to the saturation curve) can be entered through the
operator interface. If the safety margin is “breached”, the liquid
inlet solenoid valve is closed after an adjustable alarm delay
period has elapsed.
A Dräger GasLeak
Monitor with long-life infrared sensor (expected life 10+ years)
monitors combustible gas levels in the control room. The vaporizer
will be shut down if the concentration reaches 40% LEL. An
Agency-approved Safety Controller elevates the safety rating of the
08-series vaporizers to "Performance Level 4"
(SIL 3).
Electrical requirements are AC 120/220 V 50/60 Hz, 15 A, single
phase.
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05-Series: MODEL
WB-455 THRU WB-5505
These models are manufactured with
high-efficiency Maxon TOT (or similar) power burners. An electronic
thermostat (Rosemount temperature transmitter) provides
low-fire/high-fire burner modulation. All vaporizer functions are
constantly monitored by a Programmable Logic Controller with
Ethernet interface (PLC; Siemens S7-1200 or Allen-Bradley
MicroLogix-1100), which communicates with a graphic display operator
interface (color LCD display with touch screen). The operator
interface is used to monitor and display the system status; any
failure message will be displayed in plain English;
first-outage-monitor (Alarm History) and graphic trend recording are
standard. The PLC is installed together with the Honeywell flame
control module in the control panel, which is mounted in the control
room. The full-size step-in vaporizer control room can be extended
to form a maintenance house, providing additional weather protection
for operating and maintenance personnel (extended control rooms are
standard on models WB-1805 and above). All control rooms are
equipped with country-specific receptacles and light fixture.
The vaporizers are
equipped with a “smart” liquid carryover protection. Vapor pressure
and temperature are constantly monitored by a dedicated Rosemount
pressure transmitter and a Rosemount temperature transmitter. Their
signals are processed in the PLC and are compared against the vapor
pressure/ temperature saturation curve of the LPG that is being
vaporized. The properties of the LPG (Propane/Butane percentage),
and the “safety margin” (how close the pressure/temperature are
allowed to come to the saturation curve) can be entered through the
operator interface. If the safety margin is “breached”, the liquid
inlet solenoid valve is closed after an adjustable alarm delay
period has elapsed.
A Dräger GasLeak
Monitor with long-life infrared sensor (expected life 10+ years)
monitors combustible gas levels in the control room. The vaporizer
will be shut down if the concentration reaches 40% LEL. An
Agency-approved Safety Controller elevates the safety rating of the
05-series vaporizers to "Performance Level 4"
(SIL 3).
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05-Series: MODEL WB-7005
thru WB-1xxx5 These models are
usually configured for specific customer applications, for example for
use by utility companies in PeakShaving systems. Since PeakShaving
systems often operate at elevated pressures, the heat exchangers of
these vaporizers are enlarged to increase the dwell time of the LPG in
the vaporizer, thereby increasing the amount of superheat that is
transferred to the LP vapor (see above).
Other modifications can
include high-capacity water circulating pumps (to further reduce heat
stratification in the water bath); NatGas fired burners (instead of LP
fired burners); non-standard PLC configurations (i.e. for integration of
the vaporizer controls into an existing SCADA system); etc.
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STEAM VAPORIZERS
VSV-series |
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Alternate Energy Systems
offers a complete line of vertical steam vaporizers in standard
capacities from 200 gallons per hour to 3000 gallons per hour. Higher
capacities are available.
The steam tube is of
multi-pass design to transfer the maximum heat to the liquid. The tube
bundle and all propane piping conform to Section VIII, Division I of the
latest edition of the ASME Boiler and Pressure Vessel Code. The pressure
vessel carries the ASME ”U” stamp and is National Board registered.
VSV vaporizers in
standard configuration include an electronic steam temperature regulator
with pneumatic positioner (Spirax Sarco); dual liquid carryover
protection through ultrasonic liquid level transmitter in the pressure
vessel, and “smart” liquid carryover protection with Rosemount pressure
transmitter and temperature transmitter in the vapor outlet; liquid
inlet valve (solenoid valve); steam trap; and steam back check valve.
Temperature gauges in steam inlet and outlet, and in pressure vessel
shell and vapor outlet are standard.
Vaporizer design, wiring,
controls, and electrical components and their installation comply with
the latest editions of NFPA #58 and NFPA #70. All electrical components
on the vaporizer comply with Class I, Div 1, Group D.
All safety devices of the
vaporizer, including the dual liquid carryover protection, are monitored
by a programmable logic controller (SIEMENS or Allen-Bradley), which is
connected to an electronic operator interface with high-resolution color
LCD and touch screen. The operator interface provides start/stop control
for the vaporizer; it displays the system status, and any failure
conditions that may occur, in plain English (with date/time stamp). The
electrical enclosure for the PLC and the operator interface are to be
installed in a remote, non-classified location.
A small explosion-proof
enclosure at the vaporizer provides local start/stop and alarm reset
functions.
The electronic operator
interface also provides graphic TrendLine recording, first-out memory
(Alarm History), and built-in VNC server for remote monitoring and
control of all vaporizer function via the built-in Ethernet interface.
NOTE:
The steam consumption of VSV Steam Vaporizers is proportional to the
actual vaporization rate. As a "rule of thumb", 1 lb. of steam is
required for each gallon of liquid LPG (1 kg of steam for 4 kg of liquid
LPG).
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CIRCULATING
HOT WATER
BATH VAPORIZERS
VWB-series |
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Water Bath Vaporizers for
External Water Heaters (our VWB series) are specifically designed for
applications where the owner prefers to use an existing hot water
supply for the vaporization process.
Another typical application are installations where local or national
codes prohibit the use of any kind of open flame in the vaporization
process of LPG. Compared to vaporizers with local heat sources, the VWB
series offers an additional layer of safety due the lack of any
high-power/high-energy component anywhere near the LPG.
Design and configuration
of the VWB-series is very similar to the steam vaporizers (VSV-series),
including the safety and control components. |
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ALTERNATE
ENERGY SYSTEMS' BLENDERS and MIXERS |
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Alternate Energy Systems,
Inc. manufactures a complete line of LPG/Air blending and mixing systems, ranging in
capacity from 7 MM BTU to over 1000 MM BTU per hour.
Our complete line of venturi mixers and POM Mixers utilize
the finest quality material and knowledge to meet the requirement of agencies and
insurance companies governing the LPG industry.
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VENTURI MIXERS
HVS-series |
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Our
Venturi-type LP/Air mixers carry model numbers from HVS-7 (7 MM BTU/h
[1.7 MM kcal/h]) to HVS-200 (200 MM BTU/h [50 MM kcal/h]).
All HVS Systems are
designed to be used with an existing LPG vapor source, such as a
vaporizer, or as the replacement for less efficient or less reliable
LPG-vapor/air mixing systems. They come complete with steel skid, vapor
inlet header, venturi arrangements, surge tank, electric/electronic
controls, and all other equipment necessary for safe operation.
All HVS systems monitor
the gas pressure in the surge tank. Smaller systems up to two venturi
arrangements use pressure switches and standard controls. Larger systems
with three or more venturi arrangements use a pressure transmitter which
is connected to a Siemens or Allen-Bradley PLC. The PLC “sequences” the venturi
lines and controls all system safety functions. The PLC also
communicates with an Operator Interface (high-resolution color LCD
display with touch screen),
indicating system pressures, and any trouble conditions that may occur.
The PLC may also be used to “interlock” the HVS system with an external
vaporizer.
Installations where the
mixer system is separated from an open-flame vaporizer, and
installations with electric vaporizers, require the option “Explosion
Proof Control Components”, which includes explosion proof transmitters
and solenoid valves. The control panel for these mixers must be
installed in a non-hazardous location.
Beginning in March 2004,
all HVS Mixers are equipped with two solenoid valves per venturi train.
The “dynamic” solenoid valve opens and closes each time a venturi train
is activated to produce mixed gas. The “static” solenoid valves opens
when the mixer is started and stays open until the mixer is stopped, or
until a high-pressure alarm occurs. This feature provides an additional
level of safety and prevents the unwanted discharge of mixed gas in case
of a failure of the “dynamic” solenoid valve.
All systems are manufactured to the
requirements of the ASME code, latest edition of NFPA #58, and approved for Factory Mutual
(FM) or Industrial Risk Insurers (IRI) installations. The Model number (HVS) of the
venturi system designates millions of BTU per hour Propane-air mixture.
Standard models have an output pressure of 5 psi
Propane-air mixture. The output pressure can be adjusted between 4-9 psi. High pressure
models with output pressure greater than 10 psi to a maximum of 50 psi
LPG/Air mixture
are equipped with an ASME “U”-stamped surge tank and
require compressed air for operation. These air-assisted high-pressure
models are identified by an "HP" suffix (i.e. HVS-50-HP).
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PISTON OPERATED MIXERS POM |
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Alternate Energy Systems'
piston operated LPG/air mixing systems are designed around the patented
POM valve. This unique mixing valve is used in several different sizes
throughout the range of our products.
The systems described
here are intended to be used with existing LPG vaporizers, either as
replacement for less reliable LPG/air mixing systems from other
manufacturers, or in the conversion from straight LPG applications to
LPG/air systems. They are very simple in design, easy to integrate with
existing equipment, and require only AC 115 V 60 Hz or AC 220/230 V 50
Hz, single phase electrical supply for operation. They can be supplied
with several options, including automatic gas properties control; flow
controllers for PeakShaving applications; Ethernet/Internet interfaces
for remote monitoring and control; etc.
The impressive simplicity
of the POM provides the basis for a mixer design that offers the
ultimate in reliability, and that can be manufactured of any material
compatible with the medium being blended. Virtually maintenance free,
simple periodic maintenance is limited to the removal of the POM top
cover, removal of the piston, cleaning it with a solvent, wiping out the
piston chamber and replacing the piston and top cover. This can
typically be accomplished in 10-15 minutes.
By using a piston, there
are no design pressure or temperature restrictions commonly found with
diaphragms, which have high temperature restrictions or may stiffen and
crack in cold temperatures.
Compared to systems with
proportional mixing valves, which typically use differential pressure
feedback, POM systems impress with their simple installation, setup,
operation and maintenance, their unsurpassed operational reliability,
their quick response to load changes, and their turn-down ratio of 50:1
or better.
Compared to blending
systems that rely on the presence and accuracy of Vortex (or other types
of) flow meters to pre-set the blending ratio ("feed‑forward" or
"forward-control"), and then have to wait for a signal from a gas
analyzer (usually a Calorimeter) to make adjustments to the blending
ratio until the actual gas properties match the desired values
(feed-back), POM blenders are much faster to respond to load changes
(flow changes).
While the flow meter
based blenders cannot operate accurately without the presence of a gas
analyzer, POM blenders will maintain their blending ratio regardless of
the flow demand. This has been proven time-and-time again in demanding
applications. A typical example for this is the fuel supply to float
glass plants, where the periodic “reversals” (100% flow for 20 minutes;
100% to 0% in 10 seconds; no-flow for several seconds; 0% to 100% in
5-10 seconds) usually upset flow meter based blenders to the point that
some users have decided to use them for “Asset Protection” only, but not
for “Profit Protection” (keep the furnace warm, but don’t produce glass,
because the gas properties are not good enough). POM blenders, on the
other hand, have no problem maintaining the blending ratio even under
these conditions, and have therefore become a quasi-standard for the
glass industry.
Once set, the POM will
blend any two gasses at a constant ratio: the result is an LPG / air
mixture which is compatible with natural gas, regardless of the
downstream demand. The POM system is a "pushthru" system. This means
that it is not necessary to reduce the compressed air or the LPG vapor
to zero pressure during the mixing process, before compressing both air
and gas to the desired pressure. The POM system utilizes the existing
pressure in the LPG to satisfy most industrial and utility peak shaving
applications.
The most common
application is the production of a LPG/air mixture (Synthetic Natural
Gas; SNG) which is compatible with natural gas, regardless of the
downstream demand. Other applications include NatGas/Air or
NatGas/Nitrogen blending to create replacement gas for Digester Gas,
Landfill Gas, Coke Oven Gas, etc.
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ALTERNATE
ENERGY SYSTEMS' PACKAGED SYSTEMS |
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Alternate Energy Systems,
Inc. manufactures a complete line of packaged standby equipment. These packages, complete with interconnecting piping and wiring, are ready for
connection to liquid LP inlet, properly sized electrical supply, and mixed gas outlet.
These packages are skid
mounted and can be factory-equipped or field-modified to accept flow control systems, specific gravity meters,
non-standard control systems; or a large number of other options to allow the customization of any system to
meet the requirements of any specific application.
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WATER BATH VAPORIZER WITH VENTURI
MIXER PACKAGE |
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These skid mounted,
packaged systems utilize a horizontal water bath type vaporizer with venturi type mixing
system and are designed for capacities of 14 MM BTU to 250 MM BTU per hour. Manufactured
to meet or exceed requirements of the ASME Pressure Vessel Code and latest edition of NFPA
Pamphlet #58, they are approved for Factory Mutual (FM) or Industrial Risk Insurers (IRI)
installations.
Standard design output pressure between 4 and 9 psi
Propane-air mixture. Higher pressures of 10 to 50 psi are also available and require
compressed air for operation. The vaporizer model number (WB) designates gallons per hour
Propane vaporization at 0 °F inlet temperature, and the mixer model (HVS) designates
millions of BTU per hour Propane-air mixture. Electrical requirements vary with
vaporizer/mixer size. The model number for the capacity requirement governs the type of
vaporizer, burner, and safety features. Refer to Sections Vaporizers and Mixers for more
information. |
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WATER
BATH VAPORIZER WITH POM MIXER PACKAGE |
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These skid mounted,
packaged systems utilize the water bath vaporizer and piston operated mixing system and
are designed for capacities of 20 MM BTU to 500 MM BTU per hour. Complete with
interconnecting piping and wiring, they are ready for connection to liquid
Propane inlet,
properly sized electrical and mixed gas outlet.
Requiring clean, dry compressed air for
operation, the mixing system is usually shares a concrete pad with the water bath vaporizer.
Applicable for continuous duty or total stand-by, the units are designed for
better than 50:1 turndown
ratio. Complete with PLC-based control panel, the systems have automatic safety shutdown
with manual re-start.
The vaporizer model number (WB) designates gallons per hour
Propane vaporization at 0 °F inlet temperature, and the mixer is sized according to
millions of BTU per hour Propane-air mix requirements and system pressure requirements.
Refer to Sections Vaporizers and Mixers for more information.
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OTHER MODULE UNITS |
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Many of the vaporizers
and mixing/blending systems manufactured by Alternate Energy Systems, can be manufactured
inside portable, prefabricated buildings; palletized on structural steel skids to include
compressors; or customized to meet the requirement of any user. For more information,
contact your area distributor or the factory. |
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ALTERNATE
ENERGY SYSTEMS' ACCESSORIES |
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Alternate Energy Systems
has a complete line of accessories and LPG equipment to compliment and complete any
Propane standby system. We manufacture or carry a complete line of pump packages, valves,
controls, metering systems, flow recorder/controller systems and tie-in assemblies. |
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All equipment manufactured by Alternate
Energy Systems is available in various configurations and with various options. Please
consult your area distributor or the factory for your specific requirements. |
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Alternate Energy Systems reserves
the right to make changes -or add improvements- without notice and without accruing any
obligation to make such changes or add such improvements to Products sold
previously. |
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