Burners / Dual Fuel

LP Standby Systems
LP standby systems use propane, butane or a blend of the two as a substitute or supplement for the primary natural gas supply.

LP Gas -- At a Glance:

• Appearance: Colorless, odorless vapor at room temperature & pressure. Odorants added for safety.
• Heating Value:
  Propane -- 91,300 Btu/gallon (2500 Btu/cu ft)
  Butane -- 100,000 Btu/gallon (3200 Btu/cu ft)
• Transportation & Storage: As a liquid by pressurizing it. At 70°F propane can be
  liquified by subjecting it to a pressure of about 175 psig. Butane requries only 45 psig.
• Availability: Generally available in most areas of North America. Supplies may become tight during harvest season in agricultural areas due to heavy demand by crop dryers.

Propane and butane both have higher heating values than natural gas, so the same amount of heat can be generated from smaller flows of these fuels.

Unlike natural gas, propane and butane are heavier than air. This higher density, combined with the difference in Btu value, requires different pressure and flow control settings when switching from natural gas.

Propane and butane actually have lower ignition temperatures than natural gas. However, this doesn't usually have any noticeable effect on the operation of industrial burners.

The simplest LP standby system consists of a storage tank, vaporizer, if needed, and regulators and valves to control the flow of LP to the burner systems. This is a parallel system to the natural gas supply system. Because of its simplicity and low cost, it's popular for small installations with only a few pieces of burning equipment. One inconvenience of these systems is that switchovers between fuels is often done manually.