Understanding Natural Gas Furnaces

Gas-fired ovens, or natural gas furnaces, utilize naturally-occurring gaseous mixtures of carbon (C) and hydrogen (H) as their main source of fuel. These hydrocarbons can be found in isolated natural gas fields and extracted using specialized drilling rigs or they can be extracted from oil wells where they exist as off-gas.

It is a fossil energy source that has more closely aligned with renewables compared to petroleum and coal, as a result of its significantly decreased carbon emissions following combustion. Therefore, natural gas is dispensed to millions of homes globally, where it is employed to fuel central heating systems and ovens that are significantly more efficient than electric alternatives. In addition, it is a widely used fuel source for furnaces in industrial spaces.

A natural gas furnace usually works by utilizing a conventional burner, this utilizes a pilot light and a gas feed to generate a flame which is contained within a refractory burner tile. Multiple feeds may supply pure fuel and primary air or the fuel may be introduced as a pre-mix of natural gas and air to produce a steady and safe flame.

There are both advantages and disadvantages to this technology. This article will look at some of the pros and cons of utilizing a natural gas furnace in more detail.

Cost of Natural Gas Furnaces

The upfront cost of any furnace depends largely upon the complexity of its architecture, its size, and any extra functionalities that an application may need. If it requires plumbing into a supply line (which is usually the case) a natural gas furnace could be more costly to install. If a supply line is unavailable, compressed natural gas (CNG) can be utilized.

Natural gas furnaces are generally cheaper to run because of lower fuel costs and improved energy efficiency, although they are more expensive upfront. A natural gas furnace will usually reach desired temperatures more quickly than an electrically-powered alternative and consumes a lot less fuel whilst heating-up. In the long-term, this results in appreciable savings.

Performance Levels of Natural Gas Furnaces

Due to the direct generation of high-temperature combustion gas which is directed through a heating chamber by using an air blower, a natural gas furnace will heat up quickly. Carbon steel or ceramic coils positioned inside the furnace absorb this radiating heat and distribute it with high uniformity throughout the firebox. This design allows the highly-efficient and quick production of temperatures over 1200 °C (2192 °F).

Thermcraft has recently developed a custom gas-fired box furnace with six direct burners that could produce temperatures of 1260 °C (2300 °F) for a total of 2.4 million BTU's.

This performance is subject to the components it is made up of and the efficiency of each chamber in the natural gas furnace. Procedures should be put in place to avoid direct flame impingement which can result in localized, overheated spots on the radiant coils. This can cause structural fatigue which can only be rectified by replacing the element.

Emissions and Gas Generation in Natural Gas Furnaces

The main disadvantage of natural gas furnaces is the production of emissions and the possibility of sample cross-contamination. Burning any fossil fuel heightens carbon monoxide (CO) safety concerns, which can be harmful to personnel. To ensure the safety of plant operators, flue gases must be contained carefully or vented in compliance with regulatory standards, and any potential leaks must be detected and eliminated.

Given that the production of process gases and particulates is unavoidable, natural gas furnaces are generally not suitable for heat treatment of chemically-sensitive products. However, electrical furnaces regularly employ natural gas curtain burners around controlled-environment heating chambers to preserve the purity of inert atmospheres.

This information has been sourced, reviewed and adapted from materials provided by Thermcraft, Inc.

For more information on this source, please visit Thermcraft, Inc.


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