Electric Actuator for Fuel Oil Control Valve

Control Valve Actuator

In a Power Station burning both low-sulphur fuel oil and natural gas, an electric control valve actuator was installed on an outdoor fuel oil control valve application. The existing 6” ball valves which utilized a pneumatic I/P positioner and spring diaphragm pneumatic actuator wasn’t performing well. A decision was made to use a ROTORK CVA electric control valve actuator because it provides extremely precise control-valve operation with repeatability and resolution performance at less than 0.1% of full scale.

Because the valve operates outdoors, and modulates frequently to control the flow of fuel oil held in storage tanks to the fuel oil pumps, its a difficult application to get precise control. The built-in Bluetooth communications makes it easy to set up, calibrate and monitor performance.

The valve failure mode is also very important, in both loses-of-signal and loss-of-power. The specified ROTORK Actuators use a charged super capacitor and the built-in programming of the actuator control to assure proper “fail-to” in any event.

Happy Holidays and Happy New Year from CTi Controltech

We at CTi Controltech believe the magic of the Holidays never really ends and the most important gifts we share are are family and friends. Thank you for a wonderful 2014 and we wish you peace, love, and prosperity in the upcoming year. Happy Holidays and Happy New Year!

High-integrity Pressure Protection System (HIPPS) Valves

A HIPPS (high-integrity pressure protection system) is a category of "instrumented system" designed to prevent an over-pressurization condition at a process plant.

For oil, gas and chemical producers, loss of containment is a critical matter.  Over-pressure on a tank, vessel or pipeline can potentially cause explosive, flammable, toxic or hazardous chemicals to be released causing possible loss of life or adverse effects on the environment. Loss of containment can also have huge negative effects on the plants bottom line.

HIPPS will shut off the source of the high pressure before the design pressure of the system is exceeded, as opposed to a relief system which will open an alternative outlet for the fluids in the system once a set pressure is exceeded. A relief system attempts to remove any excess inflow of fluids for safe disposal, where a HIPPS is designed to stop the inflow of excess fluids and containing them in the system.  Conventional relief systems are increasingly frowned upon because they typically vent, flare or discharge hazardous or toxic fluids in to the environment.

HIPPS valves are used as the final part of an instrumented system intended to prevent an unacceptably high pressure occurring in downstream equipment. They are always arranged to fail closed and spring/hydraulic actuators are usually the only practical alternative for operation.

You can see a full application note on HIPPS relating to valves and ancillary systems here. 

Industrial Burners and Safety Systems - Part Three

Igniters

Igniters provide proven ignition energy to immediately light-off the burner. They are permanently installed. Igniters are classified as follows by NFPA:

• Class 3 special: High energy igniter (HEI) capable of directly igniting the main burner fuel. Generally consists of a spark-rod, and power pack to deliver the high voltage pulse train, and required cabling. Operation time of igniter is no longer than required to light-off burner, within maximum allowed trial-for-ignition time.
• Class 3: Low capacity igniter applied particularly to gas and oil burners. Ignites the fuel input to the burner under prescribed light-off conditions. The range of class 3 igniters generally do not exceed 4 percent of full load burner input. Operation time of igniter is not longer than required to light-off the burner, within the maximum allowed trial-for-ignition time.
• Class 2: Medium capability igniter applied particularly to gas and oil burners to ignite the fuel input to the burner under prescribed light-off conditions. The range of class 2 igniters generally is 4 to 10 percent of full-load burner input. Class 2 igniters may remain in operation to support ignition under low-load or adverse operating conditions. Class 2 igniters cannot be used to extend main burner turn-down range.
• Class 1: High capacity igniter used to ignite the fuel input through the burner. Supports ignition under any burner light-off or operating conditions. Its location and capacity provide sufficient ignition energy at its associated burner to raise any credible combination of burner inputs of both fuel and air above the minimum ignition temperature. Tests are to be performed with this ignition system in service to verify that the igniter furnished meets the requirement of this class as specified in its design. Class 1 igniters can be used to extend the main burner’s turndown, where they are in service and flame if proved.

Industrial Burners and Safety Systems - Part Two

Combustion

Combustion (or burning) is a rapid combination of oxygen with fuel, resulting in a release of heat. Air (the oxygen source) is about 21% oxygen and 78% nitrogen by volume. Most fuels contain carbon, hydrogen, and sometimes sulphur. A simplification of combustion could be listed in the following three processes.

carbon + oxygen = carbon dioxide + heat
hydrogen + oxygen = water vapor + heat
sulphur + oxygen = sulphur dioxide + heat

These products of combustion are chemical compounds. They consist of molecules, combined in fixed proportions. Heat given off in any combustion process is excess energy which the molecules must release.

Stoichiometric combustion results when no fuel or air goes unused during the combustion process. Combustion with too much (excess) air is said to be lean or oxidizing. The excess air or oxygen plays no part in the combustion process. In fact, it reduces efficiency. Visually, excess air produces a short and clear flame. Combustion with too much fuel is called rich or reducing, producing incomplete combustion. This flame appears long and some- times smoky. The oxygen supply for combustion generally comes from ambient air.

Industrial Burners and Safety Systems - Part One

Fireye Burner Safety Systems

Burners are simple devices that convert fossil fuels into heat energy. In order to achieve safe and reliable operation, each burner must be equipped with a monitoring and control system. The complexity of a safe and reliable system is relative to the complexity of the process at hand. This system can be as simple as a single burner using a single fuel, to a complex multi-burner environment where many burners fire into a common combustion chamber where multiple fuels are burned simultaneously. Conditions affecting the complexity of control systems is not necessarily dependent upon large burner input, but IS dependent upon the following conditions:

• Type of process. 
• Type of burner. 
• Multi- or single burner environment. 
• Multi or single fuel operation. 
• Safety hazard of fuel burner. 
• Local codes and standards. 
• Redundancy and reliability factors. 
• Continuous or intermittent burner operation. 

Recent technological advances require knowledge of applications and systems and should be applied only by qualified technicians. Standards are set by local authorities and must be understood and properly operated in order to assure that safety requirements are met.