Alternate Energy Systems, Inc.

A Company devoted to Your Energy Needs


Technology

Overview of Products, 
Concepts and Technology 
used by Alternate Energy Systems, Inc.

Download PDF file of this technical paper


Introduction  

 

Alternate Energy Systems' Vaporizers
Alternate Energy Systems' Mixers and Blenders
Alternate Energy Systems' complete Vaporizer/Mixer Module Units

Accessories for LPG and LPG/Air Systems
   

 Standby Plant Sizing Worksheet (Excel File)
    
Standby Plant Sizing Worksheet     for small screens    (Excel File)
 
Typical Savings on NatGas Rates for users of Standby Systems 
      
Definitions, Technical Data on LPG, NatGas, and LPG/Air Mixtures
     
     
  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.
 
  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.

 
  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.
 
  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.

 
  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)

 
  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.
 
  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/m), compared to 1020 BTU per cubic foot (9005 kcal/m) for NatGas. That is why Propane, when mixed in proper proportion with air, is an excellent supplement or replacement to NatGas.
   

 
Properties of

Natural Gas

Propane

Butane

Chemical formula   

CH4

C3H8

C4H10

Boiling point of liquid at atmospheric pressure

F
C

-259
-162

-44
-42

32
0

Specific Gravity of vapor (Air = 1)   

0.6

1.53

2.00

Specific Gravity of liquid (Water = 1)   

 

0.51

0.58

Calorific value @ 60 F (15C)

BTU/cuft
kcal/m3

1012
9005

2516
22,390

3280
29,190

BTU/gal
kcal/liter

  

91,690
6,100

102,032
6,790

BTU/lb
kcal/kg

  

21,591
11,995

21,221
11,790

Latent heat of vaporization

BTU/gal
kcal/kg

   

785
103

808
93

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

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

Ignition temperature in air

F
C

1200
650

920 - 1020
490 -   550

900 - 1000
480 -   540

Maximum flame temperature in air

F
C

3568
1964

3595
1980

3615
1991

Octane Number   

100

Over 100

92

All data is approximate. For actual properties of any particular batch, contact your fuel supplier.

    

Approximate Vapor Pressure in psig
Approximate Vapor Pressure in bar

Temperature

Propane    ---->    To    ---->    Butane

F

C

100%

95/5*

80/20

60/40

50/50

40/60

20/80

100%

-40

-40.0

3.6
0.248

1.3
0.090

                 

-30

-34.4

8
0.552

5.5
0.379

4.5
0.310

              

-20

-28.9

14
0.965

11
0.758

9.2
0.634

4.9
0.338

1.9
0.131

        

-10

-23.3

20
1.38

17
1.17

16
1.10

9
0.621

6
0.414

3.5
0.241

     

0

-17.8

28
1.93

24
1.66

22
1.52

15
1.03

11
0.758

7.3
0.503

     

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

  

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

  

30

-1.1

58
4.00

52
3.59

45
3.10

35
2.41

29
2.00

24
1.66

13
0.896

  

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

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

* HD5, Commercial Grade Propane
All data is approximate.
For actual properties of any particular batch, contact your fuel supplier.

 
  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 -44F / -42C; Butane 32F / 0C 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.

 
  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.

 
  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.

 
  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 TV Rheinland and TV Sd).

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 (-18C) 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.
   

  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 Drger 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.
 

  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 Drger 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).
 

  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.
 

 
  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). 

 
  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.

 
  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.

 
  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).

 
  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.

 
  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.

 
  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.

 
  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.

 
  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.

 
  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.

     
 

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.

     
 

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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