Boiler Combustion Efficiency System Pays Dividends

Industrial Boiler

Steam and hot water use is prevalent throughout industrial processes. Production of these two media is most commonly accomplished with a boiler, many of which are heated by combustion of fossil fuel. Fuel fired boilers of a certain size become the focus of regulatory requirements for emissions. All boilers consume what would be construed by their owners as large amounts of costly fuel. Because of their high pressure and temperature, and the presence of a controlled combustion within an occupied facility, safety is a paramount concern.

There, fortunately, is a single solution that can help to attain useful goals with the three concerns of safety, fuel cost, and regulatory compliance. Applying an efficiency controller to manage the fuel to air ratio of the combustion system will deliver benefits far in excess of the cost to incorporate the necessary devices. The three basic goals for the fuel air controller are:

• Maximize fuel efficiency
• Minimize regulated emissions
• Maintain safe operating condition

A good portion of all three goals can be accomplished through careful concerted parallel control of combustion air supply and fuel supply. The fuel air ratio must be subject to continual adjustment in response to current air conditions (which can vary on a daily basis) and the level of O2 in the flue gas. Controlling the air fuel ratio supports the following goals:

• Preventing excess fuel vapors from entering the flue and creating an unsafe condition
• Providing the correct amount of air to effectively combust the fuel supplied to the burner
• Preventing excess air flow from reducing net heat transfer to the feedwater
• Maintaining regulated emissions within required limits
• Limiting fuel consumption to the minimum necessary to meet demand

Fireye® is a leading manufacturer of flame safeguard controls and burner management systems for commercial and industrial applications throughout the world. Their products, the first of which was developed in the 1930's, enhance the safety and efficiency of all fuel fired burners.

There are numerous capabilities built in to the company's PPC4000 series of fuel air ratio controllers. Some of the more notable include:

• Precise fuel air ratio attained using parallel control of servos to regulate fuel and air supplies.
• User selected burner profiles
• Alarm contacts
• PID operation
• An array of inputs and outputs to accommodate sensors and devices needed to monitor and control boiler operation
• Compatible with other products that provide additional flame and burner monitoring safety
• Multiple boiler sequencing and cold start thermal shock protection
• On board boiler efficiency calculation
• User interface, optional larger touchscreen interface

Glance through just the first two pages of the document below to get a full description of the capability of this compact and comprehensive controller. You can get more detailed information, or get a professional evaluation of your current system efficiency, by contacting the combustion experts at CTi Controltech.

Fireye PPC 4000 Combustion Efficiency Controller from CTi Controltech

Liquid Level Measurement With Differential Pressure

Flange mount differential pressure transmitter
Courtesy Azbil North America

Industrial process operations frequently involve the use of liquid storage tanks for raw materials, in-process liquids, or finished product. Regardless of the tank usage, the data point indicating the liquid level in the tank is useful for effective process operation and safety.

Deriving tank liquid level can be accomplished utilizing a number of technologies, classed as direct or inferred. Direct level readings indicate level by interacting with the interface of the liquid surface and the unfilled area of the tank. A simple example of this would be a float, the position of which is read on a scale or transmitted to a controller. Inferential measurements are derived by directly measuring a condition which is affected in a predictable manner by the tank liquid level.

Differential pressure is an inferential methodology for determining liquid level. A differential pressure transmitter measures the total pressure of the fluid column and subtracts the pressure exerted on the surface of the liquid, delivering a signal indicating the net pressure exerted by the liquid column in the vessel. This value can be used to calculate the height of the liquid column, weight of the fluid, percentage of tank fill, or other useful values. The differential pressure method of liquid level measurement has some key features:

• Cost effective
• Limited moving parts in a complete installation, generally consisting of isolation valves for transmitter servicing
• Best applied to clean liquids with known uniform density
• Provides good accuracy over a wide operating range
• Easily mounted or retrofitted to vessel surfaces
• Low maintenance requirements
• Specifically designed seals can be utilized to provide hygienic vessel connections, or device protection from high temperature or corrosive process media

Like any measurement technology, the differential pressure method of liquid level measurement provides the best results when properly installed and maintained. There are numerous installation configurations and options to fulfill a wide variety of applications. A product application specialist can help you specify the best arrangement for your application.

Azbil Industrial Pressure Transmitters from CTi Controltech

Industrial Valves - When Butterfly Valve Is The Best Choice

Butterfly Valve
Courtesy Durco - Flowserve

Industrial process control valves are available in uncountable combinations of materials, types, and configurations. An initial step of the selection procedure for a valve application should be choosing the valve type, thus narrowing the selection field to a more manageable level. Valve "types" can generally be classified by the closing mechanism of the valve.

A butterfly valve has a disc that is positioned in the fluid flow path. It rotates around a central axis, the stem, through a 90 degree arc from a position parallel to the flow direction (open) to perpendicular (closed). A variety of materials are used in the valve body construction, and it is common to line the valve with another material to provide special properties accommodating particular process media.

What attributes might make a butterfly valve a beneficial selection over another valve type?

Manually Operated Butterfly Valve
Courtesy Ebro Armaturen

• The closure arrangement allows for a comparatively small size and weight. This can reduce the cost, space, and support requirements for the valve assembly.
• Generally low torque requirements for valve operation allow for manual operation, or automation with an array of electric, pneumatic, or hydraulic actuators.
• Low pressure drop associated with the closure mechanism. The disc in the flow path is generally thin. In the fully open position, the disc presents its narrow edge to the direction of flow.
• Quarter turn operation allows for fast valve operation.
• Some throttling capability is provided at partially open positions.
• Small parts count, low maintenance requirements.

What may be some reasons to consider other valve types?

• Butterfly valve throttling capability is generally limited to low pressure drop applications
• Cavitation can be a concern.
• Some sources mention the possibility of choked flow as a concern under certain conditions.

Butterfly valves, like other valve types, have applications where they outperform. Careful consideration and consultation with a valveexpert is a first step toward making a good selection. Combine your process know-how with the product application expertise of a professional sales engineer to produce the best solutions to your process control challenges.

Severe Service Valves - More Than Just Heavy Duty

Severe Service Industrial Control Valves
Courtesy Flowserve - Kammer

Industrial process control applications can be associated with some very stringent and challenging performance requirements for the physical equipment and components that are part of the process chain. In fluid based operations, the control valves can be a point of significant impact of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Industrial valves that are intended for application at the extremes are generally referred to as severe service valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define a severe service valve.

So, how do you know when to focus valve selection activities on severe service valves, as opposed to general purpose valves?

There are a number of basic criteria that might point you in that direction:

• Very extreme media or environmental temperature
• High pressure drop operation that may cause cavitation
• Rapid and extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid

Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are in evidence that might overrun the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of a severe service condition is identified, a careful analysis of the possible operating conditions will reveal the performance requirements for the valve.

There are numerous manufacturers of severe service valves, each seeming to concentrate on a particular niche. Kammer, a brand in the Flowserve family, has an interesting approach to accommodating the highly varied requirements of severe service applications. Their product line consists of a number of standard configurations, but also includes semi-modular components that can be combined to meet the many custom requirements of severe service applications.

I have included a technical bulletin (you know it's technical when it's not in color) that describes and nicely illustrates how the company employs various interchangeable body styles and packings with their multi-stage plug to meet a wide range of severe service challenges. Browse the bulletin, as it has some good cutaway views of valve interiors. 

You can always get more information, or discuss your special requirements, with a product application specialist. They have access to technical resources that can help with selecting the right valve components to meet your severe service applications.

Kammer Severe Service Valves For Industry from CTi Controltech

Industrial Process Control Valve Quality Detail

Wafer Style Resilient Seated Butterfly Valve
Courtesy EBRO Armaturen

Industrial process control operations have a lot riding on every component integral to the process. The operator's challenge is to get every individual element to work as planned, every time. Most process engineers would likely agree with the premise that high quality components tend to deliver higher reliability and consistent performance. Employing properly specified, high quality, componentry throughout a process installation is a generally accepted methodology for achieving the goal of consistent process output and quality.

Any process that involves fluid is bound to have valves as primary control elements. Proper selection from among the many different types used for process control, as well as the many manufacturers, can be a challenge in its own right.

How do you determine the quality level of a valve?

In industrial valves, like many products, it's in construction details that quality resides. One manufacturer, EBRO Armaturen, gives us a detailed look inside and throughout their soft seal butterfly valve. The video is included below, and it is short and to the point.

Attention to detail is what makes your operation work at its best performance level. That same level of attention also contributes to the design and manufacture of a great product. Invest two minutes to watch the video. The construction details are educational, probably things you did not know. You can get more information, or discuss your process control challenges, through contact with an application specialist.