Selective Catalytic Reduction Systems for Industrial and Commercial Boilers (SCR's)

Selective Catalytic
Reduction Systems

During the combustion process in large industrial or commercial boilers, the natural nitrogen in coal combines with oxygen forming nitrogen oxides (NOx). Nitrogen oxides in the atmosphere are unacceptable because they contribute to ground level ozone and undergo reactions in the atmosphere to form unwanted, and possibly harmful, fine particles.

Selective Catalytic Reduction (SCR) is a means of converting nitrogen oxides (NOx) to harmless nitrogen, water and trace CO2 by using an advanced emissions control system that injects a liquid-reductant agent, typically anhydrous ammonia, aqueous ammonia or urea, through a catalyst into the combustion exhaust stream.

The name "selective" derives because it selectively reduces levels of nitrogen oxides and "reduction" because of the chemical reaction where the ammonia or urea is the reducing agent converts NOx to nitrogen, water and CO2.

Commercial selective catalytic reduction systems are typically found on large utility boilers, industrial boilers, and municipal solid waste boilers. They have been shown to reduce NO by 70-95%.

SCR systems are one of the most cost-effective technologies available, while delivering great efficiency, being capable of reducing NOx emissions by up to 95 percent.

For more information on SCR's (Selective Catalytic Reduction Sytems) contact CTi Combustion.

The Eccentric Plug Rotary Control Valve (also known as the Rotary Globe)

Eccentric Plug Rotary Control
or Rotary Globe Valve
(courtesy of Cashco)

Available in either a flanged or flangeless body style, the rotary globe control valve design provides excellent service life in a wide range of applications. This rotary globe design provides front access to the valve body, allowing use of various low-noise inserts, abrasion sleeve or alternate front- end seal retainers, making it one of the most user friendly control valves when it comes to maintenance.

The rotary globe control valve is a universal control valve that can be used in most control valve applications, with particularly excellent performance on steam. Where conventional ball or globe control valves have problems with body or trim wear, the design and typical options for rotary globe control valves provides longer life. The ease and flexibility of installing characterized inserts provides noise control for gases, and cavitation and flashing control for liquids. Also because of its design, it inherently can withstand temporary distortions due to “thermal shock” without compromising continued control of the process.

A very versatile control valve that provides easy maintenance and serviceability, saving time and money for plant operations.

Flow Control Valve Tutorial

Since CTi Controltech sells, services and specifies industrial control valves in Northern California, we're always looking for helpful resources to educate our employees and our customers on control valve operation.

We recently found a great resource of tutorials courtesy of Columbia Gorge Community College that we thought we should share with you. The video we are showing is titled "Flow Control Valves" done by an instructor named Jim Pytel who does an excellent job.

Boiler MACT Help

Are you ready for Boiler MACT?
(photo courtesy of Victory Energy)

In March 2011, the Environmental Protection Agency (EPA) imposed a rule for stricter emissions limits on industrial boilers, commercial boilers and process heaters. The rule is known as Boiler MACT (which stands for "maximum achievable control technology".  It is intended to affect the emissions of hazardous air pollutants with reduction to the highest degree possible, while still considering the costs incurred by achieving these reductions.

On January 31, 2013, after several stops and starts, the EPA published final amendments to the Boiler MACT rule.

There are two classes of pollution sources - area sources (minor) and major sources. For major sources the compliance deadline is January 31, 2016.  

The rules will require some large facilities to undertake broad energy use assessments. The assessment includes inspections of boilers, operation & maintenance procedures, and drawings. A list of suggested efficiency improvements, with projected costs and an expense-recouperation timeline, must also be submitted. 

Time is running out if you're a major source of HAP (hazardous air pollutants) and you need to act. The web site boilermactsolutions.org is an excellent resource and a great place to start.

Control Valves in Industrial Control Systems

Cashco rotary
control valve

One of the most ubiquitous final control elements in industrial control systems is the control valve. A control valve attempts to regulate flow through a pipe, reacting to a signal from some type of controlling device or balancing circuit, such as a simple on/off sensor, PID loop controller, or a programmable logic device (PLC). Control valves designs are available for simple (on/off) control of flow, or for more sophisticated applications that are intended to regulate flow between a fully opened valve and a fully closed valve.

Predictive Maintenance Inspection for Critical Service Valves

Critical service valves, and the process equipment they protect, represent large capital investments in a manufacturing plant. To protect those investments, and the improve performance of your facility, a predictive maintenance inspection plan for severe service valves needs to be implemented.

Predictive maintenance inspections identify leaky valves, their severity and potential impact. The resulting report provides data that prioritizes critical issues immediately, while allowing time scheduling and budget allocation for lower priority issues.

Increasing process reliability results in greater plant efficiency and profits. Plants should routinely check their critical service valves for leaks, and repair or replace defective valves. Adoption predictive maintenance inspection will result in cost savings, greater process reliability and better safety.

Oxygen Analyzers in Industrial Combustion

Diagram of zirconia
sensor for oxygen
measurement.
(Courtesy of Wikipedia)

Oxygen analyzers are used to measure the quantity of oxygen in air or in other mixtures of gases, such as exhaust flue gas from a process. Oxygen, along with nitrogen and hydrogen, is a major component of air making up 20.9% of the air we breath. Oxygen is also used in the industrial combustion process, and when fuel is burned in presence of oxygen, CO, CO_2, and H₂O are by-products of that combustion. By measuring the oxygen in combustion process the proper air-to-fuel ratio can be maintained for optimized process efficiency. 

Oxygen analyzers are used to determine exhaust gas concentration of oxygen in many applications from internal combustion engines to combustion applications in industrial plants. Many industries such as powergen, refineries, chemical plants, cement plants, asphalt production, and agrochemicals all require oxygen measurement.