Combustion systems play a critical role in producing heat and steam in many industries. These literal powerhouses enable processes, generate energy to fuel everything from industrial furnaces to commercial kitchen equipment, and make buildings comfortable. Whatever the use, every combustion application has a common goal: a safe, reliable and efficient system.
Yet, many factors can keep facilities from attaining this goal. Extreme operating conditions, unwanted pressure drops, excessive fuel consumption, difficult installations and intensive maintenance can escalate energy use, costs and risk. A smart fuel train design with automation components engineered for burner/boiler applications can help operators achieve a combustion system capable of overcoming these challenges.
A key component is the safety shutoff valve. Safety shutoff valves provide on/off control for complete shutdown and high/low/off fuel modulation for fully open to fully closed status.
In simplest terms, when a burner or boiler operates, a reliable valve provides proper flow. When the burner is not operating, the valve prevents fuel from flowing through the pipe train. If the valves fail, the consequences range from unplanned downtime and occupant discomfort (at best) to loss of life (at worst). It is safe to say that the first step in designing a combustion system is to select reliable safety shutoff valves and actuators.
There are five critical factors to keep in mind when designing combustion systems and specifying safety shutoff valves and actuators. By considering the following, the OEMs that manufacture burner systems and the plants or facilities that operate them can ensure safety and save energy, among other benefits.
1. Optimize Fuel Flow Path
The primary job of a safety shutoff valve and actuator is to reliably control the fuel flow between the source feed and the combustion chamber. If valves cannot reliably control flow, processes do not receive enough fuel, or they consume more fuel than necessary.
Some valve manufacturers have engineered safety shutoff valves with higher flow rates and better control capabilities. Designers have changed valve shapes, volumes and capacities to optimize fuel flow through the valves and the fuel train.
Every device installed on a fuel line influences fuel flow as it moves through, causing the pressure to drop. For example, some valves slow fuel flow or change the pressure profile. This can be a problem for end-users when inlet pressure is low, yet flow must be maintained for the burner to function. The high flow rating of some safety shutoff valves minimizes pressure drop and maintains fuel flow, improving burner efficiency and productivity.
2. Reduce Energy Use and Minimize Greenhouse Gas Emissions
Energy — fuel use — accounts for much of a plant’s utility costs and affects sustainability goals. If a combustion system uses fuel inefficiently, high emissions result. Any improvements to boiler efficiency can produce energy savings and increase sustainability. Modern safety shutoff valves and actuators are designed to allow higher fuel flow rates.
Valves with higher fuel flow rates help burners run at the set higher turndown ratio, which leads to better efficiency. This decreases burner startups and improves load control, extending the life of the burner and reducing the need to purge airflow.
A way to minimize energy use is to lower the firing rate by specifying multi-position motorized actuators. They can be placed in the low or high fire position, reducing the firing rate by meeting fluctuating boiler demand and avoiding unnecessary fuel consumption.
OEMs can minimize fuel use and emissions by modifying the combustion system design itself. Traditional system designs vent gas that gets trapped between two closed valves into the atmosphere, releasing emissions. Monoblock valves with integrated vent valves, by contrast, can simplify vent piping and help make it more efficient. Additionally, recycling the trapped fuel reduces its use and prevents it from entering the air.
3. Simplify Installation and Maintenance
Long installation time, frequent maintenance and labor-intensive steps can inflate a system’s total cost of ownership. OEMs can help optimize installation and maintenance by considering product design features that can improve performance, provide time savings during maintenance and minimize component footprint.
For instance, modular or monoblock solutions can simplify product installation. By combining two valves into one body casting, monoblock options require less labor than two discrete valves. Only one person is required to install the valve onto a pipe.
Besides time and costs, some components also save space. In industrial heating applications, burners and boilers usually are fitted into tight spaces that require compact equipment. Some safety shutoff valves offer equal or better flow on smaller pipe sizes compared to older products. Using these valves, system designers can also downsize other fuel train components, save piping and reduce the overall footprint while improving performance.
In addition, flexible connections and mounting simplify installation. Modular valve bodies can be mounted in any position, which saves installation time and space in retrofits or tight areas and optimizes on/off control. Another feature that can streamline installation and maintenance is a design that reduces the number of valve bodies that OEMs, installers and end-users must stock. In one design, the valve is threaded only in the end connector, so fewer body sizes need to be stocked, and end connectors can cover the range of pipe sizes.
Long after a system has been installed, boiler efficiency will inevitably decrease as components reach the end of their standard life spans. Deterioration can be slowed, however, with disciplined operating and maintenance practices. Without proper maintenance, systems can consume more fuel and risk fuel train failure.
Active management — including preventive maintenance, testing and device upgrades when necessary — is the best way to optimize system performance. All components must be tested to confirm proper response when needed. Components with features such as accessible pressure taps can simplify maintenance with upstream and downstream pipe taps with plugs for routine testing.
4. Consider the Operating Environment
Combustion systems may be located inside or outside a facility. Those inside experience relatively temperate conditions while those outside are exposed to scorching or frigid temperatures. They may be in remote or hazardous locations or face low source pressure or minimal power supply. No matter the location or environment, combustion equipment must operate reliably. If the fuel train and its components cannot withstand the operating environment, failure and its varying range of effects can occur.
Modern safety shutoff valves are engineered to handle a range of temperatures and pressures. They are rated for temperature swings from -40 to 150°F (-40 to 66°C) and are available with NEMA-approved Type 4 enclosures that protect against the elements. They also can come equipped with built-in particle strainers that remove debris. These valves can perform in both low pressure applications, like those found in densely populated urban regions, as well as high pressure ones in remote areas. With a high close-off pressure rating of up to 75 psi, they can endure high system pressure spikes without leaking.
For harsh environments, OEMs can source low temperature, stainless steel, solenoid-actuated fuel gas shutoff valves. In hazardous environments, lightweight aluminum solenoid valves are suitable for high flow, low pressure gas applications.
5. Get the Most out of Your Partnerships
Combustion applications are extremely critical; it is vital to partner with a single-source automation solutions provider with proven reliability. When evaluating current or potential industry partners, pay close attention to their products. Safety shutoff valves absolutely must work when they are needed. Reliable products that are heavily tested for a high cycle number provide confidence that systems will operate as intended and reduce warranty repairs and maintenance calls. Testing goes hand in hand with global industry standards and regulations. Approvals must include UL, CSA, Factory Mutual (FM), RoHs, CE and IEC because combustion systems manufactured in one area may be used in different regions.
Less critical, but still highly important: Do products support multiple fuel types, and is quick shipment offered? Valves that support multiple fuel types expand the application range, and good shipping options can speed product time to the user.
A safe, energy-efficient combustion system with reduced operational costs is a common goal across the worldwide combustion application market, as are optimized flow, lower installation costs and simplified maintenance. Optimized fuel trains start with compact, robust safety shutoff valves that comply with industry standards and offer high performance in flow and pressure. Fulfilling this goal may seem highly ambitious, yet it can become a reality with the right components, intelligent product designs and an expert industry partner.
1. Available and Emerging Technologies for Reducing Greenhouse Gas Emissions From Industrial, Commercial, and Institutional Boilers, EPA, October 2020.