A Thermal Oxidizer Is Made Up of The Following Parts:
- System for waste feed. Inlet piping with isolation and control valves, flame arrester, disentrainment, or water liquid-seal drums are all examples of this.
- Fuel piping trains, including inlet piping with isolation and control valves, to the burner and pilot.
- High-temperature refractory liner in the combustion chamber.
- Inlets for air (air dampers or blowers).
- Pilot, waste burner and assist fuel burner.
- Temperature, overfire, fuel, and air controls are all included in the flame safety package.
- Sample ports for measuring the pollution-control device’s performance.
What Is a Thermal Oxidizer and How Does a Thermal Oxidizer Unit Work?
A thermal oxidizer is a combustion device that is used to reduce air pollution by eliminating hazardous air pollutants (HAP), volatile organic compounds (VOC), and odorous emissions released by industrial processes.
How Thermal Oxidizer Operation Works:
- A polluted airstream is forced through the oxidizer, usually with the help of a system fan. When the process airstream is insufficiently oxygenated for combustion, ambient air is introduced.
- The air is preheated before entering the burner/combustion chamber by passing through an air-to-air heat exchanger (if one is available). Thermal oxidizers can run with or without an inbuilt heat exchanger, depending on whether you want to save money on fuel or capital.
- To assure VOC destruction, the air in the combustion chamber is heated to a suitably high temperature and maintained at that temperature with turbulence. Temperatures of >1400°F are typical, with dwell durations of.5–1.0 second. The VOCs are converted to CO2 and H2O as a result of the thermal oxidizer process.
- The hot, clean air passes through the heat exchanger’s hot pass (if equipped).
- After that, the cooled, clean air is released into the environment.
How Does the Waste System Work for Thermal Oxidizer Systems?
After you obtain a proper answer to the question of what is a thermal oxidizer, you can start learning about its components. The selection of a thermal oxidizer begins with the needs of the plant and the process. The first step is to figure out how fast each waste stream moves (maximum, normal, minimum). Examine whether numerous waste streams can be merged or must be kept separate with separate waste trains and burners if there are several waste streams. The majority of thermal oxidizers and regenerative thermal oxidizers have only one waste train, although some have two or more.
High- and low-pressure waste streams, as well as wastes that react when mixed, are examples of different sorts of waste streams. It’s critical to have a thorough waste composition for each stream, as well as waste temperatures and pressure accessible. A booster blower or, in the case of liquid, a pump will be necessary if the pressure is low. The waste must be delivered under high pressure through the feed piping, equipment (arresters, drums, valves), and burner.
Importance Of Fuel in Thermal Oxidizer Operation
If the heat content of the waste is low, Fuel Assist fuel may be required for the thermal oxidizer. The waste is the fuel with medium-to-high waste heating properties. Pilot gas, on the other hand, will be required to ignite the waste stream or aid the gas burner. Natural gas is typically used; however, propane and other fuel gases can also be used. Oil-fired pilots or even high-energy electric ignition can be used in places where fuel gas is not accessible; however, both are more sophisticated and expensive than standard gas pilots.
Separate trains control the assist and pilot fuels. Pressure gauges, a pressure switch, and solenoid valves will be installed on the assist line (normally double block and bleed). The fuel is turned on and off by the valves, and the fuel flow for the combustion process is regulated by a modulating control valve. A pressure gauge, pressure switch, and a single solenoid valve for on/off operation are usually included in a pilot gas line. Manual isolation valves will be installed on all gasoline lines. Strainers or pressure regulators are frequently added in thermal oxidizer systems.
What Is a Thermal Oxidizer Combustion Chamber Going to Do to Enhance the Depletion Process?
Vertical, horizontal, or down-fired combustion chambers are all possible. The vertical configuration is the most common, in which the combustion chamber also serves as the stack. When secondary pollutant or heat recovery is required, horizontal combustion chambers are used. When a particle is present, the down-fired model is employed. Combustion chambers can be circular, rectangular, or multi-sided in design (with six to 20 sides). The sharp corners of rectangular chambers might make effective burner mixing and operation difficult. For large thermal oxidizers that require final assembly on the job site, multi-sided units are used. The multi-side units have a circular open corner that does not cause complications.
The configuration and location of the combustion chamber are also determined by the amount of plant space available. The thermal oxidizer is usually placed away from any buildings or other equipment. However, in other plants, there isn’t enough room for such an arrangement. In these instances, the unit may need to be mounted on the roof or on an elevated platform to ensure that the oxidizer exhaust is safely elevated.
Small units can sometimes be found inside a plant building, with the stack running through the roof. These are unusual circumstances that necessitate a safety inspection for hazardous leaks and combustible items. Because exhaust temperatures of 1400 to 1800 degrees Fahrenheit (760 to 982 degrees Celsius) must disperse, the safety of nearby people and equipment must be assessed. To keep the high temperatures under control, the combustion chamber is coated with refractory. Personnel protection shielding is included to protect operators and anyone working in the area because the outside shell of the chamber can reach temperatures of 250 to 350°F (121 to 177°C).
What Roles Do Burners Play in A Thermal Oxidizer Unit?
The most critical components in the system are the waste and assist burners. To finish the oxidization process, they offer adequate distribution, mixing, and turbulence.
Only a waste burner is required when the heat content of the trash is sufficient. A simple drilled pipe burner can be employed by a thermal oxidizer manufacturer for an application where the flow and composition range are limited.
Internal combustion, carbonization, pulsations, and poor combustion will occur if the fluxes and composition change. To avoid these issues, burner tips and mixing nozzles are typically utilized to provide the required waste-to-air distribution, mixing, and turbulence. Their designs and placement are crucial for efficient combustion with low CO and NOX emissions.
To improve functioning, some burners incorporate small secondary combustion chambers and recirculation. Flame-arrester burners are used to avoid flashback of the flame into the pipework and upstream process when the waste stream contains air or oxygen.
Air or steam atomizing burners are used to atomize liquid waste. In some circumstances with “light” liquid waste (low viscosity and density), a simple mechanical atomizer with high pressure can be used.
Finally, you are in a good position to design an air-pollution-control system if you have examined all of the conditions under which the oxidizer will function. Thermal oxidizers that have been appropriately designed should provide many years of dependable thermal oxidizer service.