A Detailed Guide for Selecting an Industrial Burner Gas Train

January 29, 2025
Time to read: 17 Minutes

As a fundamental component in manufacturing processes, burners play an essential role in supplying thermal energy. Their proper and safe operation relies on several factors, among which the selection of a suitable gas train is crucial. The gas train is responsible not only for fuel delivery to the burner but also for influencing efficiency, operational stability, and safety. Choosing the right burner gas train involves evaluating factors such as gas type, necessary pressure and flow rate, transmission distance, and safety requirements. Neglecting these factors can lead to decreased efficiency, increased safety hazards, and higher operational costs.

This article aims to provide a comprehensive guide for selecting the appropriate burner gas train by examining technical principles, relevant standards, and design considerations to best meet the specific requirements of industrial burners.

To learn more about burner gas trains, you can explore the article “A Comprehensive Guide to Industrial Burners,” which provides in-depth information on industrial burners and their various types.

The Role of the Gas Train in Industrial Burner Operation

The gas train of a burner ensures the proper transfer of gas with the required pressure and flow rate from the supply source to the burner. Any instability in pressure or delays in fuel supply may lead to burner malfunctions, decreased efficiency, or even production downtime. As a result, the gas train must be carefully designed and selected according to the burner’s unique requirements.

Key Considerations in Selecting a Burner Gas Train

These factors include key parameters that ensure the gas supply system operates safely and efficiently. The selection of a burner gas train is influenced by factors such as the type of gas, working pressure, required flow rate, pipeline length, and pressure drop—each of which plays a crucial role in the design and operation of the gas train.

Gas Type: The type of gas (natural gas, propane, butane, or mixed gases) influences the technical characteristics of the burner gas train. For example, natural gas is usually transmitted at low to medium pressures, whereas liquefied gases require lines that are more resistant to high pressures.

Working Pressure: Industrial burners require specific gas pressures, which must be supplied by the gas train.

Required Flow Rate: Depending on their type and application, industrial burners need specific amounts of gas per time unit. The pipeline diameter should be chosen in a way that meets the required flow rate with minimal pressure drop.

Pipeline Length and Pressure Drop: As the length of the pipeline increases, the pressure drop also increases. When designing gas trains for longer distances, using pipes with a larger diameter or installing pressure boosting stations becomes necessary.

Relevant Standards and Regulations

The selection of the burner gas train must comply with national and international standards. Some of the key standards are as follows:

ASME B31.8: Gas Transmission and Distribution Piping Systems
API 5L: Seamless and Welded Pipes
NFPA 54: National Fuel Gas Code
Iranian National Standard 7595 (Equivalent to BS EN 676:2008): This standard is for gas burners with a fan and outlines the requirements for using a gas train.

According to Iranian National Standard 7595 (Equivalent to BS EN 676:2008), all parts of the burner gas train, positioned after the manual adjustment valve, must be designed for the supply pressure and be safeguarded with suitable safety equipment to prevent any overpressure. All components of the gas train, for hazardous gases, should be made from materials with suitable durability. Maintenance instructions must specify maintenance intervals and appropriate lifespan or cycles to ensure safety.

Iranian National Standard 7595 for Equipment Used in Burner Gas Train

Adhering to Iranian national standards such as Standard 7595 for gas supply equipment in burners ensures the safety and efficiency of the systems. his standard provides technical details for valves, filters, regulators, and safety equipment against excessive pressures.

Manual Shut-off Valve

A manual quick shut-off valve should be considered upstream of all controllers to isolate the burner. Although this valve is not provided with the burner equipment, the manufacturer’s instructions must outline the requirement for its installation. Additionally, burners must be equipped with these manual shut-off valves as they are essential for proper startup and operation.

Filter/ Strainer

A filter/strainer must be installed at the inlet of the shut-off valve to prevent foreign objects from entering. The maximum hole size of the strainer must not exceed 5.1 millimeters, and the mesh should prevent particles larger than 1 millimeter in diameter from passing.

Gas Pressure Regulator

The feed gas must be regulated by a pressure regulator for operation and startup to ensure that the pressure at the main burner nozzle, with a capacity over 2 kW, remains stable. The main burner and pilot can be controlled independently.

For a deeper understanding of the various types of gas regulators, you can explore the article ” Gas Regulators; An Overview of 11 Different Types and the best Brands.”

Access to the pressure regulator should be designed so that it can be easily adjusted, but precautions must be taken to prevent unauthorized adjustments. A safety valve must be installed downstream of the gas pressure regulator, and the safety valve should discharge into a safe space.

Safety Devices for Gas Overpressure

If a gas pressure regulator is not installed or is removed from the system, a protective device must be put in place to prevent excessive gas pressure. This device, known as a shut-off valve, will stop the gas flow to the burner in the event of a regulator failure.

Safety Devices Against Low Gas Pressure

The burner should be equipped with a low-pressure protection device to perform a controlled safe shutdown if the gas pressure drops below the set limit.

Automatic Shut-off Valves

Every burner should have two safety shut-off valves installed in series. In situations where the main flame is ignited by a pilot flame, the ignition feed gas must be controlled using one of the following methods:

The feed gas must be under the control of the main safety shut-off valve downstream and equipped with a pilot gas limiter.
The feed gas should be under the control of the safety shut-off valves.

Leak Detection System (Valve Testing System)

The leak detection system is used for capacities above 1200 kilowatts and checks the solenoid valves for leakage after each burner shutdown. A leak test is conducted before restarting the burner after any power failure, and the test is performed in two stages:

Step 1: In case of a controlled shutdown, Solenoid Valve 1 closes immediately, and Valve 2 stays open for a short time, which causes the pressure between V1 and V2 to decrease through the butterfly valve. Once Valve 2 closes, the pressure between V1 and V2 should remain constant with no drop.
Step 2: Solenoid Valve 1 opens for a brief moment, causing an increase in the pressure between V1 and V2. The pressure between the valves should not drop below the set pressure of the gas pressure relay throughout the testing period.

If the pressure falls below the set level or the pressure between the two valves decreases during the first phase, the leak detection system will block the gas circuit.

Introduction to Equipment Used in the Burner Gas Train

The gas train of the burner consists of various components and equipment responsible for transferring, regulating, and controlling natural or liquefied gas from the source to the point of consumption. These components are designed to ensure the safe, efficient, and standard-compliant transfer of gas. Below are the main components of the burner gas train and their respective functions.

Piping: It is responsible for transferring gas from the source to the consumer. Steel materials are used for high-pressure and industrial systems, whereas polyethylene is commonly used for low and medium pressures, especially in urban pipeline construction.

Solenoid Shut-off Valves: The main solenoid valve is responsible for controlling the gas flow in either a single-stage or two-stage manner. The safety solenoid valve provides the ability to shut off the flow in emergency situations.

Gas Filters: They are responsible for removing suspended particles, dust, and impurities from the gas flow to protect sensitive equipment like regulators and burners. Gas filters are typically installed at the station inlet or before the regulators and end-use devices.

Gas Pressure Regulator: Its role is to reduce and control the gas pressure to the required level for consumption. Pressure regulators are categorized into high-pressure regulators and low-pressure regulators.

Safety Valves: These are used to vent excess gas to prevent sudden pressure increases, typically installed after the regulator in the burner gas train.

Pressure and Temperature Measuring Devices: These monitor the gas pressure and temperature in different lines, including manometers and thermometers.

Warning and Safety Systems: These systems detect leaks and hazardous conditions, such as pressure switches and pressure sensors.

High Pressure Gas Train | raadman — A view of high pressure gas train

Different Types of Gas Trains

Burner gas trains are classified into three categories based on the input pressure and the burner’s maximum capacity consumption: low-pressure gas train, high-pressure gas train, and multi-block gas train.

Low-pressure Gas Train

If the input pressure of the main gas train is less than 5 psi, the gas train equipment follows the diagram in Figure 2. In this case, low-pressure regulators (maximum input pressure of 360 millibar) are used.

Equipment Introduction | raadman — Introduction to low pressure gas train equipment

High-pressure Gas Train

If the input pressure of the main gas train is higher than 5 psi (360 millibar), high-pressure gas trains are utilized. The difference in this type of gas train is found in the regulators used. Figure 3 illustrates a graphical depiction of high-pressure gas trains fitted with shut-off valves.

Equipment | raadman — Introduction to high pressure gas train equipment

Multi-block Gas Train

It is one of the advanced and integrated systems for managing and controlling gas flow in industrial burners and high- and low-pressure thermal processes. In this type of gas train, a multi-block valve is used, combining several different functions (such as flow shut-off, pressure regulation, safety, and gas filtration) into one integrated unit. Figure below provides a graphical representation of a low-pressure gas train equipped with a multi-block valve. Figure 5 also depicts the multi-block valve used in the gas train.

Low-Pressure Gas Train with Multi-Block Valve | raadman — Low-pressure gas train equipment with multi-block valve

Multi-Block Valve | raadman — Low-pressure gas train with multi-block valve

Devices | raadman — Equipment of low-pressure gas train with multi-block valve

Calculation of Inlet Gas Train Pressure for the Maximum Operation of Burner

Given the importance of the issue, the selection of burner gas train components is made according to the available resources and the burner’s operational conditions. The calculations related to the gas train and the pressure losses caused by its components are explained in detail, and the results are presented as follows.

The minimum inlet gas train pressure, considering the pressure drop in the various components of the burner gas train, is calculated according to the equation below.

$P_{in} = \Delta P_{f} + \Delta P_{R} + \Delta P_{SV} + \Delta P_{GV} + \Delta P_{CH} + \Delta P_{CC} + \Delta P_{BGV}$

The parameters in the above equation are as follows:

$\Delta P_{f}$ : Pressure drop caused by the filter

$\Delta P_{R}$ : Pressure drop caused by the regulator

$\Delta P_{SV}$ : drop caused by the safety valve

$\Delta P_{GV}$ : drop caused by the main gas valve

$\Delta P_{in}$ : Minimum required inlet gas train pressure

$\Delta P_{CC}$ : Pressure drop caused by the boiler chamber

$\Delta P_{CH}$ : Pressure drop in the burner combustion chamber (for G25 gas, this parameter must be multiplied by 1/3)

$\Delta P_{BGV}$ : Pressure drop caused by the butterfly valve

In order to determine the minimum pressure needed for the burner gas train in a steady-state condition, the pressure drop values for each component of the gas train are initially obtained from the corresponding technical diagrams. Subsequently, with these values and Equation 1, the required inlet pressure is calculated and provided.

The minimum inlet pressure calculated by this method is based on the steady-state operational condition. Therefore, it is necessary to distinguish between this condition and the static pressure when the burner is off.
It is recommended that, to ensure the proper functioning of the burner, the inlet pressure of the gas train be 10 millibars higher than the calculated value.
The pressure drop parameter caused by the boiler combustion chamber is typically provided by the manufacturers.

The significance of selecting the correct gas train in industrial burners

Industrial burner gas trains directly affect the safe and efficient operation of the equipment. The design of these trains should consider factors such as working pressure, gas flow rate, the type of gas used, and process requirements. Compliance with standards like ISIRI 7595 and the use of safety valves, filters, and regulators are vital for ensuring safety and optimizing performance.

Proper design reduces the risks of leaks and explosions and cuts maintenance costs. The adoption of modern technologies like multi-block valves increases the efficiency of gas trains due to their integrated design and high safety features.

Industrial groups such as raadman, with their specialized knowledge and experience, offer a full range of services from the design to the installation of burner gas trains. These services are customized based on operational requirements and project-specific needs and are conducted in line with international standards. The precise design and implementation of industrial gas trains not only reduce costs but also guarantee sustainable efficiency and long-term safety of processes. This becomes even more crucial in industries that rely on stable energy channels and highlights the central role of gas trains in industrial infrastructure.

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