Dividends From Boiler Combustion Efficiency System

Fuel fired boiler operation can be costly. Maintaining high
combustion efficiency returns substantial cost savings.

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 application experts at Classic Controls.

Fuel Air Ratio Controller for Combustion Efficiency from Classic Controls, Inc.

Laser Spectroscopy Applied to Oxygen Measurement

Combining the analytical function of laser spectroscopy with the simple installation package of an industrial transmitter, the Sick TRANSIC100LP provides direct real time in-process oxygen measurements in a wide range of industrial processes. The short video shows how the unit is easy to install and uncomplicated to operate as part of a process measurement and control system.

Fast results and low maintenance are hallmarks of TRANSIC100LP operation. There are no sample prep requirements and no consumables. Sick explains the operating principle of the transmitter in their technical data sheet...

"The TDLS Tunable Diode Laser Spectroscopy is primarily used in high-end gas analyzers and is characterized by its highly selective measurement capability. The oxygen properties are used for O2 measurement: That means O2 atoms in the near infrared range are stimulated at specific wavelengths. A laser diode modulates the radiation precisely over an absorption peak. The high-energy radiation transfers energy to the O2 atoms and the signals becomes weaker. In the measuring probe, the laser beam hits the O2 atoms and is weakened according to the concentrations of oxygen present there. A receiver measures the intensity of the arriving radiation and accurately determines the absorption. One distinct advantage of laser spectroscopy is it´s insensitivity to possible interference. For O2 in particular, there is no absorption of other gases in the range of sampled absorption peaks."

Watch the video for more detail and some application examples. Share your gas analysis requirements and challenges with process measurement specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Filled Impulse Lines With Pressure Sensors or Gauges

Pressure transmitters and gauges are often installed
with impulse lines.
Image courtesy Yokogawa

Pressure sensors intended for use in industrial process measurement and control applications are designed to be robust, dependable, and precise. Sometimes, though, it is necessary or beneficial to incorporate accessories in an installation which augment the performance of pressure sensors in difficult or hazardous environments. There are some scenarios where the sensor must be isolated from the process fluid, such as when the substance is highly corrosive.

A way to aid pressure sensing instruments in situations where direct contact must be avoided is by using a filled impulse line. An impulse line extends from a process pipe of vessel to a pressure measurement instrument or sensor. The line can have a diaphragm barrier that isolates the process fluid from the line, or the line can be open to the process. There are best practices that should be followed in the design and installation of an impulse line to assure that the line provides a useful transmission of the process pressure to the sensor and whatever degree of isolation or protection is needed remains in effect.

The filled impulse line functions via the addition of a non-harmful, neutral fluid to the impulse line. The neutral fluid acts as a barrier and a bridge, allowing the pressure sensing instrument to measure the pressure of the potentially harmful process fluid without direct contact. An example of this technique being employed is adding glycerin as a neutral fluid to an impulse line below a water pipe.

Glycerin’s freeze point is lower than water’s, meaning glycerin can withstand lower temperatures before freezing. The impulse line connected to the water pipe may freeze in process environments where the weather is exceptionally cold, since the impulse line will not be flowing in the same way as the water pipe. Since glycerin has a greater density and a lower freezing point, the glycerin will remain static inside the impulse line and protect the line from hazardous conditions.

The use of an isolating diaphragm negates the need for certain considerations of fill fluid density, piping layout, and the need to create an arrangement that holds the fill fluid in place within the impulse line. System pressure will be transferred across the diaphragm from the process fluid to the fill fluid, then to the pressure sensor. It is important to utilize fluids and piping arrangements that do not affect the accurate transference of the process pressure. Any impact related to the impulse line assembly must be determined, and appropriate calibration offset applied to the pressure sensor reading.

An essential design element of a filled impulse line without an isolating diaphragm is that the fill fluid must be compatible with the process fluid, meaning there can be no chemical reactivity between the two. Additionally, the two fluids should be incapable of mixing no matter how much of each fluid is involved in the combination. Even with isolating diaphragms employed, fluid harmony should still be considered because a diaphragm could potentially loose its seal. If such a break were to occur, the fluids used in filled impulse lines may contact the process fluid, with an impact that should be clearly understood through a careful evaluation.

Share your pressure measurement requirements and challenges with experienced application specialists, combining your own process knowledge and experience with their technical expertise to develop an effective solution.

Digital Valve Positioner

D3 digital positioner is suitable for linear or rotary valves
Image courtesy of  Flowserve - PMV

A digital positioner is primarily intended for use with modulating control valves. Full featured units will accommodate single or double acting actuators, as well as rotary and linear valves. A digital positioner is a precision instrument and should be treated with a commensurate amount of care to prevent damage during installation and setup.

The positioner will read a control signal input, such as 4-20 mA. The internal processing of the digital positioner will regulate the operation of air supply and venting valves integral to the positioner, regulating the motive pressure on the actuator and the resulting valve trim position. Positional feedback of the valve position is provided by a potentionmeter.

Units can be provided with one of several different communications options to enable setup and diagnostic information to be transmitted across a network. Good air supply quality and pressure will assure the best positioner performance. Various spindle and bracket arrangements are available to facilitate proper mounting of the digital positioner to the valve actuator.

The use of a digital positioner enables superior modulating valve control and repeatability, along with improved diagnostic information. More detail is contained in the document provided below. Share your fluid control challenges with valve automation experts, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

PMV Digital Valve Positioner from Classic Controls, Inc.