Friday, July 22, 2016

Understanding the Magnetic Level Indicator (MLI)

magnetic level indicator
Magnetic Level Indicator
(courtesy of Orion)
The magnetic level indicator (MLI), also called a magnetically coupled liquid level indicator or a magnetic level gauge, is in wide-spread use throughout process industries around the world. Originally designed as an alternative to sight glass gauges, MLIs are now commonly specified in new construction and plant expansions.

Principle of Operation 

Magnetic level indicators use the law of magnetism to provide liquid level information. They can activate a switch or provide continuous level data via a transmitter. Unlike a sight glass, magnetic coupling allows the MLI to measure liquid levels without direct contact between the externally-mounted visual indicator and the fluid in the vessel.

A magnetic field consists of imaginary lines of flux originating from both the north and south poles that completely surrounds the magnet. This field acts on other objects (magnets or ferromagnetic materials) in the form of forces. When a magnetic field acts upon another body with sufficient force to influence it, the pair are said to be magnetically coupled to each other.

In an MLI, the magnets within a float and an indicator are magnetically coupled. The float, located inside the chamber, dynamically tracks the surface of the liquid as it rises and falls. The magnet assembly inside the oat generates a magnetic eld that penetrates through the chamber wall to couple with the visual indicator.

Typical applications include: 
magnetic level indicator
Various options for MLI
  • Alkylation units 
  • Boiler drums
  • Feedwater heaters
  • Industrial boilers
  • Oil / Water separators
  • Process vessels
  • Propane vessels
  • Storage tanks
  • Surge tanks
  • Wastewater tanks
Advantages of the MLI 

A magnetic level indicator is often used in applications where a sight glass (or glass sight gauge) is unsafe, environmentally risky, or difficult to see. 

Typical shortcomings of glass sight gauges include:
  • High pressures, extreme temperatures, deteriorating seals, and toxic or corrosive materials may cause a risk of fugitive emission of dangerous substances. 
  • Some chemical materials within a process vessel or storage tank can attack the glass, causing discoloration of the sight gauge, thus decreasing level visibility. 
  • Liquid/liquid interfaces can be very difficult to read in a sight glass particularly if the liquids are of similar color. Clear liquids can also be difficult to see in a sight glass. 
  • Liquids that tend to coat or build-up on surfaces can hinder visibility by forming an opaque film on the glass. 
  • To cover a large measuring span, sight glass assemblies typically must be staggered using multiple sections. 
The key reasons for selecting an MLI over a sight glass are:
  • Improved safety due to the absence of fragile glass and a substantially reduced number of potential leak points. 
  • Greatly increased visibility 
  • Reduced maintenance. 
  • Easier initial installation and addition of transmitters and switches without interrupting the process 
  • Lower long-term cost of ownership and legitimate return-on-investment benefits. 
  • Single chamber measurement over 20 ft. (6 m) without staggering chambers.

Thursday, July 21, 2016

Electric Heaters 101: Get the Heat Out of the Heater

cartridge heater
Internal view of swaged cartridge heater.
Metal-clad electric heating elements share one very common and very important requirement for optimal performance - get the heat away from the resistance wire and into the work as efficiently as possible.

At the heart of most resistance type electric heaters is a nichrome alloy wire, or ribbon, referred to as the heating "element". It acts as a resistor to the electrical current and gives off heat. With sheathed heaters, the heating element is then wrapped in some sort of electric insulating material such as mica or magnesium oxide (MgO), and then encased in a metallic sheath. Unfortunately, both the electric insulator and the metallic sheath act as heat insulators to some degree, which cause the nichrome wire to get very hot. Nichrome wire has a melting point of 1400 deg. C (about 2500 degrees F). While this sounds high, the wires and ribbons can easily exceed these temperatures in normal operation when not allowed to adequately conduct heat.

Very often electric heater failure can be directly attributed to poor conductivity between the heating element and the process medium. Whether it be a cartridge, strip, band, duct or immersion heater the principle is the same - lower resistance wire temperatures equal longer heater life.

When applying cartridge heaters, special care has to be taken to the bore tolerance of the hole where the heater is inserted. The tighter the bore tolerance, the more efficiently the high internal wire temperatures are conducted away.  Tolerances of several thousandths of an inch can change the life expectancy of a cartridge heater significantly.

Strip and band heaters require tight, full surface area clamping to maximize life and performance, while duct heaters and immersion heaters require circulation to transfer heat away from the element, and keeping resistance wire temperature within reasonable operating limits.
strip heater
Internal view of band & strip heater.

Any situation where the heater is exposed to a stagnant air gap (or stagnant fluids) will most likely result in over temperature of the wire and failure at that point.  With this in mind, anyone applying traditional resistance type, electric heating elements must be very aware of maintaining very intimate contact between the heating element and the item or process being heated.

Whenever applying electric heating elements, the consultation of an applications expert is always recommended. They will be able to consider many other operational factors such as wire watt density, conduction properties, control scheme and overall thermal system dynamics.

Wednesday, July 20, 2016

Basics of Industrial pH Measurement

pH and ORP sensors & control
pH sensors & control
(courtesy of ECD)
Analytical measurement and control of pH within a system is necessary for many processes. Common applications include food processing, wastewater treatment, pulp & paper production, HVAC, power generation, and chemical industries.

To maintain the desired pH level in a solution, a sensor is used to measure the pH value. If the pH is not at the desired set point, a reagent is applied to the solution. When a high alkaline level is detected in the solution, an acid is added to decrease the pH level. When a low alkaline level is detected in the solution, a base is added to increase the pH level. In both cases the corrective ingredients are called reagents.

Accurately applying the correct amount of reagent to an acid or base solution can be challenging due to the logarithmic characteristics a pH reaction in a solution. Implementing a closed-loop control system maintains the pH level within a certain range and minimizes the degree to which the solution becomes acidic or alkaline.

An example of an automatic pH level control system is a water treatment process where lime softened water is maintained at a pH of 9, using carbon dioxide as a reagent. As the untreated water (or influent) enters the tank, the pH is continuously monitored by the pH sensor. The sensor is the feedback device to the controller where the set point is compared to the control value. If the values are not equal, the controller sends a signal to the control valve that applies carbon dioxide to the tank. The reagent is applied to the tank at varying rates to precisely control the pH level. With the pH level at 11 detected by the sensor, the controller commands the control valve to open and introduce more carbon dioxide. As the increased carbon dioxide mixes with the influent, the pH is lowered in a controlled manner. Reaching the set point, the carbon dioxide flow is minimized and the process is continually monitored for variation. The effluent is the treated water that is discharged out of the tank. The process continues to provide the lime softened water at the desired pH level.

Tuesday, July 19, 2016

Industrial Level Control White Paper: How to Minimize Your Insurance Risk with Overfill Protection

Tank Overfill Prevention
Tank Overfill Prevention

The Oil & Gas industry is no stranger to incidents that have resulted in stricter regulations and guidelines for operating safely and responsibly. Since the Buncefield overfill accident in 2005, overfill prevention has had a spotlight on it from global regulatory organizations to make sure this type of accident did not happen again. Both American Petroleum Institute (API) and Health and Safety Executive (HSE) have instituted new guidelines to help ensure proper overfill prevention through management systems and safety-integrated systems of level measurement in storage tanks. All of these guidelines are targeted at reducing the risk of a Buncefield-type incident occurring at any storage terminal on a global scale. There are benefits to risk reduction that go beyond just incident prevention, including a reduction in liability insurance for storage terminals. Storage terminal operators and insurance providers have different perspectives on liability insurance and how they evaluate and minimize the risk.

Assessing Insurance Risk

Insurance agencies look at how much a storage terminal location has minimized the risk of events deemed catastrophic to the environment and employees. Overfill prevention is one aspect of the risk reduction that is reviewed for liability insurance. The insurance agency will review the local jurisdictional requirements and industry guidelines when determining the insurance rates. During this review, the insurance agent is looking for evidence that the safety measures are properly maintained, as well as having each safety measure functioning properly. It is important for the devices that are used as safety guards to have an ability to be easily tested and maintained. Many insurance agencies will make recommendations based on failure modes they have experienced to ensure safety. These recommendations include processes to maintain operation, but also features of the level transmitters or switches themselves. Level transmitters for tank level should have internal diagnostics that are able to identify issues when they exist. Level alarms (or switches) should be able to be proof tested either electronically or manually to ensure proper functioning. By choosing the appropriate level transmitters and switches with these capabilities, the overall risk of an incident is reduced and the insurance premium is much lower.

Assessing Operation Risk

From the insurance customer’s perspective, the narrative changes. Plant operations staff are concerned with the ability to operate profitably based on expenses and costs. Storage terminals have to deal with both fixed and variable costs that must be managed in order to operate profitably. As it was noted above, this can be managed by making sure that risk has been reduced across the terminal. Operators can receive the recommendations of the insurance agencies and work to make the best selections of their level instrumentation based on those recommendations. Typically, they can expect to be audited by the insurance entity (external or internal) to review their level instrumentation annually, so it is important to stay compliant. Operators take on a large amount of risk by not following the recommendations of the insurance agencies and could face fines for not complying with industry standards if an incident were to occur. They can evaluate the level instrumentation on the market, but it can help to get guidance from suppliers that parallels the insurance agency recommendations.

Level Transmitter and Switch Providers

By selecting the appropriate level instrumentation, a storage terminal site can demonstrate that it has taken measures to reduce the risk of overfill or other hazardous situations. As level instrumentation technology has advanced, continuous level transmitters have become more prevalent in storage terminal level control. There are many transmitters on the market that have self- diagnostics that are constantly running to assess the health of the device. Based on the storage terminal’s assessment of critical tank levels, the transmitter can identify when these levels are reached, allowing ample time to remove product from the tank as part of the overfill prevention system. Beyond previously using point level controls, continuous level measurement devices can provide real time level readings to control rooms while tanks are being filled/emptied. This helps the operator reduce the risk of having a dangerous event by knowing the tank level in real time. A further risk reduction step is to utilize additional point level controls as the failsafe alarms. The continuous level device can have the output set to alarm certain functions, but if those were to fail, then the additional alarms at high and low level can provide emergency shut down or emergency pumping of product to avoid an overfill. These devices can be as simple as a mechanical level switch with manual proof test capability, or they can be as sophisticated as an electronic point level switch using ultrasonic technology with built in self-test diagnostics. Either of these are industry acceptable and provide an added layer of protection to meet industry standards and reduce overfill risk.

Over ll Protection Resources

There are many level instrumentation products on the market that can help an owner/operator reduce the risk of an overfill spill or catastrophic event. They range from simple to complex, but all add to the goal of reducing the possibility of an incident. You can download the Magnetrol Tank Overfill Protection document here.

Thursday, July 14, 2016

Process Heaters, Furnaces and Fired Heaters: Improving Efficiency and Reducing NOx

process heater
Process Heater
(courtesy of
AMETEK Process
A process heater is a direct-fired heat exchanger that uses the hot gases of combustion to raise the temperature of a feed owing through coils of tubes aligned throughout the heater. Depending on the use, these are also called furnaces or red heaters. Some heaters simply deliver the feed at a predetermined temperature to the next stage of the reaction process; others perform reactions on the feed while it travels through the tubes.

Process heaters are used throughout the hydrocarbon and chemical processing industries in places such as refineries, gas plants, petrochemicals, chemicals and synthetics, olefins, ammonia and fertilizer plants. Some plants may have only two or three heaters while larger plants can have more than fifty.

Most of the unit operations in these plants require red heaters and furnaces. These operations include:
  • Distillation 
  • Fluidized Catalytic Cracking (FCC) 
  • Alkylation 
  • Catalytic Reforming 
  • Continuous Catalyst Regeneration (CCR) 
  • Thermal Cracking 
  • Coking 
  • Hydrocracking 
Typical process heaters can be summarized as follows: 
  • Start-Up Heater — Starts-up a process unit where it is required to heat up a fluidized bed of catalyst before adding the charge. 
  • Fired Reboiler — Provides heat input to a distillation column by heating the column bottoms and vaporizing a portion of it. Used where heat requirement is greater than can be obtained from steam. 
  • Cracking Furnace — Converts larger molecules into smaller molecules, usually with a catalyst (pyrolysis furnace). 
  • Process Heater — Brings feed to the required temperature for the next reaction stage. 
  • Process Heater Vaporizer — Used to heat and partially vaporize a charge prior to distillation. 
  • Crude Oil Heater — Heats crude oil prior to distillation. 
  • Reformer Furnace — Chemical conversion by adding steam and feed with catalyst.
Read the full document below:

Wednesday, July 6, 2016

Introducing Avenisense Plug & Play Sensors & Transmitters

Avenisense Devil
Avenisense Devil
Avenisense manufactures embedded plug & play sensors and transmitters for the continuous monitoring of oil and gas, fuels, lubrication oil quality, beverages, chemicals, paints & inks. Avenisense high-tech instruments enhance the profitability, safety of industrial processes, and play a key role in reducing the maintenance cost of lubricated machineries.

Avenisense has five branded sensor and transmitter products with designs for multiple markets and applications:
  • DEVIL for fuel monitoring - Embedded fuel quality insurance during transportation & distribution steps
  • DEVIL solvents gels polymers - A unique density/viscosity sensor for the monitoring of chemical reactions & mixes
  • DEVIL paints inks coatings - A unique embedded density/viscosity sensor for the painting, printing, and coating industry
  • DEVIL heavy oils - A unique embedded density/viscosity sensor for heavy petroleum products
  • DEVIL kerosene, fuels, gasoil - A unique embedded density/viscosity sensor for light & medium petroleum products
  • DEVIL lubricants & crude oils - The ultimate embedded density/viscosity sensor for lubricating & crude oils
  • DEVIL OEM - Ask us for the density/viscosity sensor that matches your colours
  • CACTUS® - Oil quality sensor for real-time, online condition monitoring, embedded onto rotating machineries
  • WATERACT® - Water activity sensor for harsh applications, moisture in oil sensor with integrated temperature probe
  • WATERACT®-AIR - High performance pressure & temperature sensor for harsh environments
  • NORTHDOME - The unique gas density transmitter
  • NORTHDOME FULL - The unique molar mass & normalized gas density transmitter
  • SPHERE® - High performance pressure & temperature sensor for harsh environments
Check out the video below for more information about Avenisense:

For more information, contact:
BCE (Belillove Company-Engineers)
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999

ASI Advanced Safety Integrity, SIL-2 Certified Point Gas Detector

SensAlert ASI Point Gas Detector
SensAlert ASI Point Gas Detector
The Sensidyne SensAlert ASI provides enhanced protection and dependability for critical safety applications where personnel, processes, and facilities are at risk. The thirdparty certified SIL-2 SensAlert ASI offers dependability and versatility while remaining the easiest to install, commission, operate, and maintain.

The product is third-party certified to IEC61508 Level 2 (SIL-2) for both hardware and software with certification to global hazardous area and performance standards. The Test-on-Demand feature with on-board gas generator provides remote functionality checks with generated gas while Predictive Sensor End-of-Life Indication provides advanced warning of impending sensor failure.

SensAlert ASI is a universal instrument platform for toxic & combustible gas detection and oxygen monitoring. Intrinsically safe or explosion proof installation configurations with options for remote sensors and gassing, duct mount, and sample-draw maximize application versatility. Intrinsically safe or explosion proof installation configurations for remote sensors and gassing, duct mount, and sample-draw maximize application versatility. The sensor head accepts all Plus Series sensor technologies – infrared, catalytic bead, and electro-chemical. Assignable and configurable relays together with communication options provide broad flexibility. The SensAlert ASI I.S. sensor head can be remote mounted up to 100 feet (30m) from the transmitter providing a useful option to position the transmitter in a personnel-accessible location while positioning the sensor closer to potential hazards.

For more information, watch the video below:

For more information, contact:
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999