Energy must be applied in a controlled and safe way in many industrial and thermal processes. One of the most common methods of providing thermal energy is the use of gas burners. Their high efficiency, ease of use, low emissions, and straightforward control make them vital for various industries and even residential heating systems. However, to guarantee optimal safety and performance, it’s crucial to have a comprehensive understanding of gas burner equipment and how they function.
What is a Gas Burner?
A gas burner is a device that generates a stable and controllable flame by using gaseous fuels (such as natural gas, liquefied petroleum gas (LPG), and various process gases) along with the required combustion air to provide the necessary heat or energy for a system. They are widely used in heating systems, including boilers and furnaces, and are available in various sizes and capacities depending on specific operational requirements. Proper burner efficiency is essential for minimizing fuel consumption, reducing environmental pollutants, and optimizing the overall performance of thermal systems.
Gas Burner Equipment
A gas burner consists of a set of components and subsystems designed to ensure safe and efficient combustion. Gas burner equipment include electrical, mechanical, and control elements, all working together to fulfill specific tasks. Gas burners are categorized into two types: nozzle-mix and premixed. This article focuses on the equipment of nozzle-mix gas burners.
The article “Gas Burners; main applications and key features” offers an in-depth discussion on gas burners. To gain more information, it is advisable to review this article.
Burner Combustion Head
combustion head is one of the critical elements of gas burner equipment, responsible for creating a turbulent airflow with vortices in front of the burner as the combustion air passes through it. These turbulences help improve the mixing of fuel and air and increase flame stability. The careful design of the combustion head, including factors like fuel spray patterns, the positioning of gas nozzles, and components such as diffusers or swirlers, directly influences the efficiency of fuel and air mixing.
In cases where fuel and air are not properly mixed, resulting in a non-homogeneous mixture, high-temperature zones or fuel-rich areas may form, leading to the production of NOx and carbon monoxide. Therefore, the correct design of the combustion head plays a crucial role in reducing pollutants, enhancing flame stability, and improving the overall performance of the burner.
Burner Ventilation System
Another important component of gas burner equipment is the burner ventilation system, which is responsible for providing the combustion air required for the burner. Ventilation systems can be classified into two main types: natural draft and forced draft.
Natural Draft System
In this type, the necessary combustion air is supplied without the use of mechanical equipment, relying purely on natural draft. The mechanism of the natural draft ventilation system is based on buoyancy force and the density difference between the hot gases inside the combustion chamber and the surrounding air. In this process, the lower density of the hot gases compared to the surrounding air creates a natural suction, directing the air flow upward.
These systems have a simple design due to the lack of mechanical equipment, but to create suction, the combustion chamber in them must have a relatively high height. Additionally, an air damper is employed to regulate the flow of incoming combustion air. The natural draft ventilation system is one of the most common ways to supply combustion air in fired heaters.
Raadman RSun series burners are among the top choices for industrial fired heaters, with the required air being supplied via the natural draft ventilation system.
Forced Draft System
Forced draft ventilation system is made up of parts such as an electro motor, fan, inlet air damper, silencer, and sand trap (dust collector). The electro motor provides the necessary rotational power to the burner fan impeller. When the impeller rotates, combustion air is blown towards the burner, and when mixed with the fuel gas, the combustion process occurs. In some electro motors, inverters are used, allowing the speed of the motor to be adjusted, which ensures precise regulation of the burner airflow to meet different requirements.
An air damper, located at the fan inlet, features multiple adjustable blades that open and close. Its primary function is to control the airflow into the burner, ensuring an optimal fuel-to-air ratio for efficient combustion.
The silencer and sand trap are secondary components of the burner ventilation system that significantly contribute to its overall efficiency. The silencer is responsible for reducing the noise generated by the airflow. The sand trap filters dust and suspended particles, preventing contaminants from entering the ventilation system and protecting the internal burner components from damage.
In premixed burners, an air filter is installed at the fan inlet to prevent dust and suspended particles from entering the air supply system. This filter enhances combustion quality and improves the overall efficiency of the burner.
Electronic System
An electronic system is another key piece of gas burner equipment, made up of two primary circuits: the power circuit and the control circuit. The power circuit includes components such as bimetals, contactors, and switches, which are responsible for switching the current ON and OFF. The control circuit includes relays and controllers, which handle burner management and combustion control. AutoFlame controller is one of the most widely used controllers, especially in the burners manufactured by Raadman Industrial Group.
Burner Control System
A control system in this case consists of a range of electronic and mechanical components and circuits that are responsible for monitoring, regulating, and safeguarding the combustion process. This control system ensures accurate fuel and air supply, flame monitoring, and prevents burner improper operation. Relays, controllers, air and fuel actuators, flame detectors, and switches are key parts of the burner control and command system.
In older control systems, relays were used to manage burner operations. These relays could only turn the burner ON and OFF, lacking the capability for modulating control (continuous regulation of the burner output). On the other hand, modern burners utilize advanced control systems like AutoFlame.
These systems allow for continuous and modulating burner operation by accurately regulating the fuel and air supply, thereby optimizing energy usage, improving combustion efficiency, and reducing emissions. AutoFlame Mk8 M.M smart controller, which manages both the boiler and burner simultaneously, can control all essential parameters at the same time.
Air and Fuel Actuators
An air or fuel actuators are critical parts of a gas burner, which opens and closes the air and gas valves mechanically, pneumatically, or electronically. In modern burners, actuators are typically electric and receive signals from the burner controller. With the help of the actuator, the amount of combustion air and fuel entering the burner is adjusted based on its capacity. Actuators can be used for the gas modulating valve or the air damper.
Flame Detector
Another essential component of a gas burner is the flam detector, which monitors the presence or absence of a flame. If the flame goes out or fails to form, the sensor sends a command to the burner controller to cut off the fuel supply. These sensors are available in different types, depending on the system design and requirements.
These sensors can be infrared (IR) or ultraviolet (UV) types. They detect the presence of a flame by measuring the emitted wavelength, ensuring safe burner operation. AutoFlame detectors are among the most popular and widely used flame detection sensors, which are also employed in raadman burners.
Another type of flame detector is the frequency flame sensor, which detects the presence of a flame by analyzing the frequency of the flame oscillations and reports it to the burner control system. Among these, the Durag flame sensor is notable.
A different type of flame sensor is the ionization flame sensor or ionization rod, which identifies the presence of a flame by the ionization of surrounding gases and sends this information to the burner control system.
Ignition System
In gas burner, the ignition system provides the initial energy for combustion by generating an ignition. This method is primarily used in small burners, where the energy required for ignition is relatively low. For larger burners that need higher initial energy, a pilot burner is used. The pilot burner functions as an independent ignition source, lighting the main fuel. Essential components of the ignition system include the spark electrode and the ignition transformer.
Ignition Electrode
An ignition electrode is a metal component that creates an electric arc by receiving high voltage from the ignition transformer, igniting the fuel-air mixture. Located near the gas flow path, it is manufactured in different shapes and lengths based on burner design. Its high resistance to heat and corrosion, along with an adjustable position, ensures effective ignition and improved burner performance.
Ignition Transformer
An ignition transformer functions by converting regular input voltage (110V or 220V) into a high voltage required for generating a spark to ignite the air-fuel mixture. These transformers are classified based on their output voltage and power rating. Some offer higher voltage with lower current, while others are optimized for different burner sizes. A crucial characteristic of an ignition transformer is its high-voltage insulation capability.
Pressure switch
The pressure switch monitors the air pressure in forced draught burners or the gas pressure in fuel pipelines. Once the pressure reaches the designated threshold or falls below it, the internal contact of the switch is triggered, sending a signal to the burner controller to prevent operating if the pressure is inadequate.
Pressure switches are classified into two main types: air pressure switches and gas pressure switches. The air pressure switch is used to measure the fan air pressure, while the gas pressure switch monitors the incoming gas pressure and shuts down the burner if the pressure is inadequate. One of the most common pressure switches is Dungs, which is used in raadman burners.
Burner Gas Train
Another crucial part of gas burner equipment is the gas train, which transfers gas with appropriate pressure and flow rate from the supply source to the burner. The components of the gas train are designed to ensure the safe, efficient, and standard-compliant delivery of gas. Any fluctuation in pressure or delay in fuel supply can disrupt burner operation.
To learn more about gas trains and how to choose the right one, consider reading the article “A Detailed Guide for Selecting an Industrial Burner Gas Train“.
Depending on the type of burner, it may be necessary to adhere to specific standards such as the National Standard 7595 (translated from BS-EN 676), NFPA 85, and ASME B31.8 for the design and installation of the gas train to ensure the safe and stable operation of the system. The components of the burner gas train include:
Manual Shutoff Valve: This valve is placed at the beginning of the gas train and is intended for burner isolation. Burners are required to be fitted with these manual shutoff valves.
Gas Filter: A gas filter is used to remove suspended particles and contaminants from the gas stream to prevent damage to the equipment. Gas filters are usually installed before the pressure regulator.
Gas Manometer: Gas manometers are used to monitor the gas train pressure.
Gas Pressure Regulator: The device is used to decrease the gas train pressure to the required level for the burner. Additionally, regulators absorb pressure fluctuations and help maintain a constant pressure to the burner.
Relief Valve: The safety valve is usually placed after the gas pressure regulator and functions to release excess gas resulting from sudden pressure surges.
Safety Valve: The safety valve is a device that allows gas to flow only when it receives a positive signal from the burner control. If the flame detection sensor reports the flame being out or if any hazard such as pressure drop or overpressure occurs, this valve automatically closes and the gas flow is interrupted.
Main Valve: The gas modulating valve or main valve is a component used to control the gradual flow of gas into the burner. This valve opens and closes in stages or continuously, adjusting the gas flow according to the burner’s required capacity.
The Importance of Proper Selection and Adjustment of Gas Burner Equipment
Gas burners play a crucial role as one of the most important pieces of equipment in thermal and industrial processes, providing controlled and safe thermal energy. Through advanced designs and the use of precise and efficient gas burner equipment, these burners enable high efficiency, reduced fuel consumption, and a decrease in environmental pollutants.
The most critical components of gas burner equipment, including ventilation system, electronic control system, ignition system, flame detection, and gas train, all operate together to ensure the combustion process is safe and efficient. Proper selection and adjustment of gas burner equipment, along with regular maintenance, not only enhances burner performance but also helps avoid potential issues and safety risks.
Raadman gas burners, utilizing the latest technologies and advanced control systems such as AutoFlame, are an ideal choice for various industries and heating systems. Ultimately, understanding the operation and gas burner equipment, especially in industrial environments, is essential for achieving maximum efficiency and safety.
