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Comfort Heating Systems/Saving Natural Resources
Published in Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo, Energy Conservation Guidebook, 2020
Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo
The gas burner of a furnace or heating system is primarily responsible for the mixing of air and gas in a proper ratio to ensure combustion. The 15:1 air/gas ratio is quite common in most geographical areas of the United States.
Computational simulation of incineration of chemically and biologically contaminated wastes
Published in Journal of the Air & Waste Management Association, 2021
Paul Lemieux, Timothy Boe, Anna Tschursin, Martin K. Denison, Kevin Davis, Dave Swensen
A natural gas burner (firing rate of approximately 5861 kW [20 mmBtu/h]) is located at the feed end of the rotary kiln. The burner is used to heat- the kiln during startup and to co-fire when processing waste material that has a low heating value. For typical operation, the burner is shut off because waste material will release enough heat to operate the rotary kiln (i.e., self-sustained burning). For the system modeled, the air flow into the kiln (leakage air, combustion air) results in an oxygen concentration at the kiln exit of approximately 11% O2 dry (i.e., a stoichiometric ratio of approximately 1.8 for the kiln). The gas flow at the kiln exit is stratified and ranges in temperature from approximately 1482°C (2700 °F) near the bed to approximately 260°C (500 °F) at the top of the kiln, resulting in a bulk exit temperature of approximately 1038°C (1900 °F).
Combustion characteristics of various biogas flames under reduced oxygen concentration conditions
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Biogas flame for the existing natural gas burner has been investigated numerically under distributed combustion conditions in this study. Reduction of the oxygen concentration has been provided in order to achieve distributed combustion by simulating of combustion products recirculation. It can be readily said that distributed combustion provides more uniform thermal field inside the combustor. Therefore, it is concluded that biogas can be burned under distributed combustion conditions. In addition of this conclusion, different types of biogases on thermal field have also been investigated and it has been revealed that different types of biogases have not affected thermal field substantially. The mixture temperature has been determined as 600 K to simulate a real combustion process and its effect on thermal field has also been examined within the present study. It is demonstrated that the high mixture temperature leads to reduced emission levels in terms of NOX and CO. When the oxygen concentration in the oxidizer is decreased, the predicted NOX and CO levels are nearly zero whereas the predicted CO2 levels are higher slightly. It can be consequently concluded that distributed combustion method burning biogas fuel can be used in any combustion equipment such as furnace, and gas turbine. In this way, both more uniform thermal field and less emission level can be obtained.
A concept and industrial testing of a superheated steam rotary dryer demonstrator: Cocurrent-triple pass design
Published in Drying Technology, 2019
Y. Chryat, M. Esteban-Decloux, C. Labarde, H. Romdhana
The partially desuperheated steam is recycled by a SHS-blower, superheated by a heat exchanger and then supplied to the inlet of the dryer. The removed vapor from the product is supplied to a cooling unit for energy recovery. A wet scrubber is used to clean the exhaust vapor by spraying water. The use of water also leads to cooling down the SHS up to the saturation state. The saturated steam is then condensed. The non-condensable gases (e.g., air, VOC) are removed and burned off. The vapor can be superheated up to 600°C with combustion gases produced by a natural gas burner (22–110 kW). The combustion furnace (3 m length, 1 m diameter) is made of steel covered with refractory concrete. The superheater consists of series of 6 shell-and-tube exchangers. The first two series consist of 50 tubes each (21.3 mm diameter, 1 m length). The last 4 series consist of 28 tubes each (26.9 mm diameter, 1 m length). Within each tube series, the SHS flows through a set of tubes and exchanges heat with the combustion gases flowing outside the tubes in cross flow. The outlet combustion gas is finally used in a heat recovery exchanger to preheat the primary combustion air.