Heating Gas The Green Way
In a world of growing environmental awareness, it is exceedingly imperative to recognize technologies that offer both economic and environmental benefits.
One such technology is Cold Weather Technologies line of Natural Gas Dryline Heaters.
Cold Weather Technologies (CWT) heaters have been commercially marketed since 2005. Both Tecvalco Ltd. and the CWT heaters have a solid history of engineering and design behind them. Utilizing a unique Heat Driven Loop (HDL) technology, these heaters show major improvements over the traditional glycol-bath heaters, especially in improved safety and reduced environmental impact.
They drastically reduce the amount of glycol used in the heater, and replace the highly-ineffective and primitive fire tube with a much more efficient system of heat transfer. Also, removing the glycol bath allows the CWT heater to be more responsive to the inlet conditions of the natural gas, this, combined with the fact that the heater is only burning ounces of fuel gas, means a major reduction in how much gas the unit uses. Some field units have seen as much as 82 per cent reduction, but the standard falls more around 70 per cent.
Kenneth McCarthy, a Senior Project Engineer with National Grid, and Gregory Gerber, a Senior Foreman with the same company, noted that they compared the CWT heater to a wide range of alternate heating solutions before settling on their 2.3 million BTU/hour unit. It was installed at the Canarsie Gate Station in Brooklyn, New York back in January of 2008.
Of particular concern for National Grid was the existing footprint that they had to work within. “The heater could fit within the existing footprint of the existing heater,” they noted. “In addition, additional site permitting as required by the installation of a building for the modular boiler system would not be required.”
But this was just one area they found their new heater excelled in. They were also pleased by the significant reduction in the quantity of glycol required, as well as by the fact that the heater can run off existing on-site power supply. The reduction in glycol means eliminating a large cost associated with the fluid and containment, as well as being yet another way that the CWT heater is more environmentally responsible.
The greatest benefits were that the heater runs silently and reliably, and that it is simple to understand and operate. National Grid also noted that they have already seen a significant reduction in fuel gas consumption, and “less fuel consumption translates directly into a reduction in greenhouse gas emissions,” they added.
“I would strongly recommend that [anyone looking for a new heating solution] consider CWT heaters as they provide efficient, dependable operation, and hold advantages over the traditional water bath heaters. Their simplified design approach provides a system which is easy to understand and operate; requiring minimum training and maintenance,” McCarthy said. “Their heater has lived up to its expectations and as a result we have since contracted for the purchase of an additional heater for another site.”
National Grid has since purchased two more large-capacity heaters for their operations.
The CWT heater operates under a vacuum, with the air being removed from both the evaporator and the condenser parts of the heater. This allows the water to boil at a much lower temperature, resulting in a more effective heat transfer, and therefore less fuel gas required for heating. As a nice side affect, the vacuum also means there is no corrosion inside the unit.
The heater requires no external utility power, as it runs on 700 mV internally generated by a furnace power-pile that sits in the standing pilot. This is sufficient to operate the management and control system for the unit.
What makes this unit a favorite in the field is the simplicity of operation. The controls are all very familiar typical furnace controls. There are no moving mechanical parts, and very little maintenance. In comparison to the conventional fire tube, the CWT heater is extremely safe to light, and is practically silent.
The CWT dry line heater has undergone extensive testing by the Saskatchewan Research Council, which helped establish much of the data on the heater line. Additionally, SaskEnergy helped test the prototype of the unit in Maidstone and Melville, both in Saskatchewan, Canada. In the first 12 months that the Melville unit was in operation, SaskEnergy saw a 54% reduction in fuel gas used. SaskEnergy has since put into operation a significant number of units.
There are a wide variety of modular units available, starting at 70,000 Btu/hour, going up to 770,000 Btu/hour. Combining a number of units allows the company to provide heaters up to as much heat as required. Because the units are designed to deliver heat into process as required, regardless of the load, a stage-firing capability is important. This allows the heater to deliver just the right amount of heat into the fluctuating natural gas load.