Flanged and Screw Plug Electric Heating Assemblies for Industrial Applications

Flanged Tubular Electric Heater Assembly
Hotwatt

Electric heating, though not the most energy efficient means of delivering heat, provides some distinct advantages as a means of controlling the temperature or thermal component of fluids and solids throughout commercial and industrial settings.

Tubular elements are a common form of electric heater. Essentially a metal tube with resistance wire and electrical insulation inside, tubular elements can be configured into almost uncountable shapes and sizes. Manufacturers typically offer a range of standard sizes and ratings, but that should never deter you from making contact to discuss your ideas for a custom arrangement.

Two mounting schemes that are readily used on tanks or other vessels are the screw plug and flanged heater assemblies. In each case, tubular heaters are bent in a "U" shape and fitted into either a pipe flange or a threaded plug. A junction box encloses the electrical terminations for the heating elements, providing a single ended assembly that can be easily mounted to an industrial standard mechanical connection. These assemblies are useful for tank or vessel OEMs that wish to provide a fluid heating option to their customers.

Examples of Screw Plug Electric Heaters
Hotwatt

Electric heat enables a properly configured controller to proportion heat into a subject fluid across a wide range, from very small packets that could be fractional percentages of full capacity to the fully available output of the heater. The units are compact, rugged, and can be configured to accommodate a broad array of industrial environments and applications.

Selecting or specifying a unit is uncomplicated. Determine the amount of heating capacity needed, then select the assembly mounting type (flange, screw plug, or other). Select an element sheath material that is compatible with the process media and a termination enclosure that suits the surrounding environment. Application assistance is available from product specialists who are well versed in the available options and can help you specify an assembly that provides excellent performance and an extended service life.

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

Process Heater
(courtesy of
AMETEK Process
Instruments)

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:

Process Heaters, Furnaces and Fired Heaters: Improving Efficiency and Reducing NOx from Belilove Company-Engineers

On-Off Temperature Control Using PLC Ladder Logic

Diagram of on / off control.

In control theory, an on–off controller is a feedback controller that switches abruptly between two states. It is often used as a control method for a process which can tolerate an ongoing, changing band of change, referred to as the hysteresis. A very common example for temperature are residential thermostats. They control the temperature of your home, turning off at your comfort setting, then after some significant change occurs, and they turn on again to eliminate that difference. The process cycles continually.

A common method of temperature control is an on/off control system using comparison instructions in a PLC program where outputs are energized until the set point is reached.

The video below provides a temperature control example where the heater turns on when the temperature falls to or below 597 degrees, and turns off when the temperature reaches 603 degrees or more.

To control the circuit, S1 is programmed in the heater output circuit. Addressed to the move instruction is a thermocouple that provides an analog value to the temperature. The temperature is moved from the source to the destination when S1 is activated and is displayed on the LED panel.

Using the less than or equal to, and greater than or equal to, instructions addressed to the same integer file the source values have A and B are compared to control the heater. With source a less than source be at the less than equal to instruction, the low temp and heater outputs are enabled. The heater remains on as long as the low temp output is true and the high temp output is false.

As the temperature rises above source B at the less than or equal to instruction, low temp turns off and heating continues. Reaching 603 degrees or more, the high temp output is enabled, since source A is equal to source B of the greater than equal to instruction.

When the high temp output is true, the heater turns off and remains of until the temperature reaches 597 or lower.  The cycle is repeated to maintain the average set point temperature at the other at 600 Fahrenheit.

(Re) Introduction to BCE (Belilove Company-Engineers)

Electric Heating Elements in Life Science and Analytical Instruments

Life science and analytical instrumentation are designed to determine the identity and structure of inorganic and organic liquids and gases, and then detect, separate and analyze their individual compounds.

These processes require the application of heat to the sample. Very specialized heating elements are normally required to achieve the temperatures (300 deg. C to 500 deg. C) to achieve breakdown of the samples into base components. Since sample sizes are normally very small, the heating elements must also be small, react quickly, and be easy to control.

Typical applications for these heaters are mass spectrometers (MS), high performance liquid chromatographs (HPLC), other gas chromatography (GC), flow instrumentation, toxic gas analyzers, and laboratory culture instruments.

BCE is a leading designer and fabricator of high performance, highly accurate, fast responding heating elements for life science and analytical instruments.

Intrinsic Safety for Hazardous Areas Explained

Intrinsic Safety Barriers are devices that limit power delivered from a safe area into a hazardous area. The possibility of an explosion is prevented, not merely contained (by a housing or a conduit). The total energy is maintained within safe limits, not electrical energy (voltage and current), eliminating an ignition from excessive heat. The use of an intrinsically safe design offer many cost and safety advantages.

• Easy access to components - no time spent opening/closing explosion proof enclosures.
• Safety assured due to low voltage system.
• Use of standard wiring, cable runs, and light gauge cable.
• Calibration and maintenance the same as if in a general purpose area.
• No special hazardous area procedures for opening enclosures, area gas testing, or shut-down process.
• Simple use of plug-in modules.

The document below provides an excellent explanation into Intrinsic Safety and goes far more in to the background, concepts, principles, and devices used in this approach to safety in hazardous areas.

Intrinsic Safety Explained from Belilove Company-Engineers

For more information, contact:

BCE

P.O. Box 55936
21060 Corsair Blvd
Hayward, CA 94545

www.belilove.com
Phone: (510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

Designing a Process Control Loop? Or maybe a Custom Thermal System? Call a Sales Engineer.

Sales Engineers are a valuable,
readily available resource.

Are you an engineer tasked with designing a new control loop for a manufacturing line? Or perhaps you're an engineer at an OEM designing a new piece of equipment requiring an electric heater, control and sensor?

Call a sales engineer to make your job easier.

Projects and tasks are best completed and accomplished through the proper application of the right resources. There exists an access point to high level technical knowledge and assistance that can be easily tapped and brought to bear on your successful task or project completion.

Local distributors and representatives for process equipment and control manufacturers provide services that may help you save time and cost, while also achieving a better outcome for the entire project. Consider a few elements the technical sale rep brings to your project:

• Product Knowledge: Sales engineers will be current on product offerings, proper application, and capabilities. They also have information regarding what products may be obsolete in the near future. This is an information source at a level not generally accessible to the public via the Internet.
• Experience: As a project engineer, you may be treading on fresh ground regarding some aspects of your current assignment. There can be real benefit in connecting to a source with past exposure to your current issue. 
• Access: Through a technical sales engineer, you may be able to establish a connection to “behind the scenes” manufacturer contacts with essential information not publicly available. The rep knows people, makes it his/her business to know the people that can provide answers to your  application questions.

Certainly, any solutions proposed are likely to be based upon the products sold by the representative. That is where considering and evaluating the benefits of any proposed solutions become part of achieving the best project outcome.

Develop a professional, mutually beneficial relationship with a technical sales team. Their success is tied to your success and they are eager to help you.

Electric Heating Element Types and Selection Guide

The following, courtesy of Hotwatt,  is a good reference for selecting an electric heating element for both OEM and process heating applications.

Included are all types of industrial electric heaters - cartridge, band, tubular, immersion, duct, circulation and cable.

OEM & Industrial Electric Heating Element Catalog by Hotwatt from Belilove Company-Engineers

Handy Electric Heating Engineering Constants and OHMs Law

Here is a very handy "cheat-sheet" for calculating Ohm's Law and other engineering constants that come in very handy when calculating wattages, voltages and current draw of electric heating elements.

These equations are important when sizing any type of electric heating element including cartridge, band, immersion, or flexible heaters.

To calculate any wattage, voltage or current, you need to know two of the variables and refer to the diagram in the document to calculate the third.

Another important quick reference chart is Fahrenheit to Centigrade temperature conversion as shown below.

When You Need a Custom Heating Element or Thermal System Design

OEMs often need custom designed heating elements for their equipment. Designing an electric heating element, or a complete thermal system, requires both electrical and mechanical engineering skills. Often, you can save time and money by calling in an expert with the proper experience to assist.

Belilove Company-Engineers has decades of experience developing custom thermal solutions in many industries - from low tech to cutting-edge high tech, from foodservice appliances to semiconductor processing equipment, Belilove has "been there, done that". So the next time you need an electric heating element, temperature sensor, or controller, Think Belilove.

In the Market for an Industrial Annunciator? Here's a Guide to Help

Alarms and Annunciators

Annunciators are found in industrial control rooms, boiler rooms, power substations and just about any type of process control operations room where the process conditions need to be closely monitored and where constant status indication is important.

Here is an outline for the primary selection criteria for an integrated logic alarm annunciator:

Chassis

• Panel mount
• Surface mount
• Rack mount

Alarm Points

• How many alarm points do you have? Annunciators break down alarm points by "cell" and you call out the number of cells based on the layout desired. For instance, a 1x4 would be 1 annunciator cell tall by 4 cells wide. 

Pushbuttons (and Location)

• Occupying bottom right module cell space
• On the bottom right trim of the chassis
• Located remotely

The Available Panel, Box or Cabinet Space Available

• Dictates how alarm points and pushbuttons are arranged.

Networkable or Stand-alone?

Configuration via software?

Event recording?

Do you need electrical outputs?

• Audible and visual signals: horn, beacon, bell
• Common Trouble Alarm (CTA) Relay: notification of any alarm within the system (commonly used for remote beacon or dial-up) 
• Group CTA functions: for critical and noncritical groups 
• Auxiliary Contact Repeat Relay: individual repeater output per input 
• Reflash Alarm Relay: alarm counter 

Field contact voltage?

Source voltage?

Alarm type grouping? 

For a detailed annunciator selection guide (courtesy of RONAN Engineering) visit this annunciator selection guide link.

Thermocouple Basics - Wire Type, Connectors, Construction

Industrial thermocouples, as the temperature sensor in a thermal system, are explained in the video below.

Seebeck Effect
(image courtesy of Wikipedia)

Thermocouple "Types", based upon standardized color designations is discussed, as well as thermocouple connectors, polarity and some aspects of construction (such as grounded vs. ungrounded vs. open tip).

Thermocouples are a fairly accurate, economic temperature sensor used in many industrial applications. They operate on the "Seebeck Effect" which is the phenomena of dissimilar metal conductors producing a measurable voltage difference between two substances.

Thermocouples are used widely in industrial thermal system design in industries such as power generation, primary metals, pulp and paper, petro-chemical, and OEM equipment.

For more information contact:
Belilove Company Engineers
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

Thick Film Heating Elements: An Excellent Choice for Custom OEM Thermal Designs

Custom Thick Film
Heaters and Circuits

Thick film heating elements, originally designed for the automotive and military industries, are manufactured by depositing several layers of conductor, resistors and dielectric on to an insulator via a screen printing process. The dielectric is normally some type of glass or ceramic and provides electrical insulation for the screen printed heating tracks.

Thick film heating elements are almost always custom designed for OEM applications. They can be designed in all shapes and sizes, and have an ability to provide very high watt densities with excellent controllability. The largest markets for these heating elements are appliances, analytical instruments, automotive, semi-conductor, medical device, scientific and military equipment.

Because of their inherent low mass, and their ability to carry high watt densities, thick film heaters are very efficient and are an excellent choice where a rapid heat-up (response) is required.

Advantages of thick film heaters are:

• Watt-Density up to 175 watts per sq. in. 
• Operating Temperature to 500 deg C
• Low Profile
• Excellent Control
• Very uniform heat profile
• Temperature sensors can be included on the heater
• Custom heating profiles
• Very rapid heater response
• Vibration and shock resistant
• Very customizable shapes, sizes and wattages

Electric Heating Systems for Liquid-Gas Vaporization

Electric Circulation Heater

Hydrocarbon and non-hydrocarbon based gas products are transported and stored at low temperatures. The most common examples of liquified gasses are liquified natural gas, butane, propane, nitrogen, and oxygen. In liquid form gases are more convenient and efficient to transport, however once at their destination, they must be changed back to the gaseous state.

There are many ways to accommodate the phase change from liquid to gas and picking the best option is dependent on many criteria including plant location, climate conditions, available energy sources, and infrastructure available.

Transitioning from liquid phase to gas phase is a gradual process usually taking place at higher pressures, through several containment vessels, heat exchangers or heating coils which slowly warms the liquified gas.

Some thermal heat exchanging systems use fluids such as hot oil, hot water or a glycol-water solution to efficiently transfer heat to the liquified gas.

Advantages of Epoxy Electrical Feedthroughs Over Glass-to-Metal and Ceramic Seals

Epoxy Electrical
Vacuum Feedthrough

Advances in semiconductor and medical device development has continually challenged manufacturing processes in ultra-clean environments. Getting power and control signals into high vacuum chambers has always been difficult. The vacuum seal has to be tight and not allow any contamination so that product quality is maintained.

Historically glass-to-metal seals for wire feedthroughs have been the choice in these industries, but are constrained in size, geometry, flexibility and electro-magnetic shielding. At the same time, semiconductor and medical device equipment have an increasing need for higher power, more control, better monitoring, and increased signal shielding. These ever changing requirements, which push the capability of glass-to-metal seals,  open up opportunity for an alternative technology - epoxy electrical vacuum feedthroughs.

Engineered epoxy electrical feedthroughs offer the best of all technologies. Shapes, angles and curves are not a problem. Virtually any kind of shielded wire or cable can be used and still maintain a tight seal. And as equipment design requirements continue to challenge vacuum seals with space and shielding requirements, the advantages of epoxy vacuum seals look to be a promising solution as the technology itself continues to advance.

While glass-to-metal feedthroughs have advantages in high temperature and corrosive applications, many of todays semiconductor and medical device applications don’t see these conditions. In these lower temperature, and non-corrosive applications, the lower cost, easy prototyping and more flexible design capability of epoxy feedthroughs make them very attractive alternatives.

The epoxy's ability to flow and fill spaces completely make it an excellent choice for any special shapes and sizes a vacuum chamber may require for access.  For the most part, epoxy feedthroughs can be used in most applications where glass-to-metal or ceramic feedthroughs are used (with the exception of temperature and corrosion issues outlined above). In some applications, organics are not allowed, and the epoxy feedthrough would be excluded from these as well.

One additional advantage is that custom epoxy vacuum feedthroughs can be quickly provided in very small quantities for prototyping and R&D.

For more information on epoxy feedthroughs, visit this page.

Advancements in Electric Resistance Heaters - Ceramic Heating Elements

Aluminum nitride, high performance electric heating elements using Tungsten traces on ALN. Product manufactured by Durex and Oasis Materials.

• Power Densities up to 2500 Watts per square inch
• 0-400º C in a quarter of a second
• Extreme temperature uniformity
• Inert in acidic solutions
• Custom line widths and resistance values available
• Encapsulated Tungsten RTD trace
• 3D shapes and configurations
• Thermal conductivity of Oasis' Aluminum Nitride (ALN) is 190 W/mK
• Thermal conductivity of pure tungsten is 170 W/mK

Basics of OEM and Industrial Electric Heating Elements - Part 2

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Basic Heat Equations

Electric Heating Elements

It would appear at first that calculating all of the heat transfers and losses in a design would be a daunting task. Fortunately a number of equations were developed that help simplify this task. First the equations were divided into three tasks: the wattage needed to heat a material to a specific temperature in a given amount of time; the wattage needed to overcome the losses at operating temperature; and a special calculation needed to reach a melting or vaporizing point.

This equation calculates the amount of wattage (W) needed to raise the temperature of a material a specific amount in °F (ΔF) in a given number of hours (T), you first need to know the mass (m) of the material being heated and its specific heat value (c):

m × c ×ΔF

W=  -------------------

3.412 × T

The mass and specific heat of some materials may be found at www.hotwatt.com/table1.htm for metallic solids, www.hotwatt.com/table2.htm for solids other than metals, and www.hotwatt.com/table3.htm for certain liquids and gases.

Basics of OEM and Industrial Electric Heating Elements - Part 1

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Electric heating elements
for OEM and Industry
(courtesy of Hotwatt)

The simplest definition of an electric heater is any device that changes electrical energy into heat energy. But from that simple explanation, electric heaters explode into a myriad of types, sizes, applications, and designs depending upon what’s being heated, the degree of heating needed, and the method by which the heat is applied.

The measure of electrical energy is called the Joule after its discoverer, James Prescott Joule. Through numerous experiments, Joule determined that the quantity

(Q) of heat transferred from electrical energy is proportional to the square of the current (I² ) multiplied by the resistance (R) for the period of time (t) through which it passes:

Q ∝ I² × R × t

However, one seldom sees a reference to Joules used in modern electric circuits. Instead, the controlling factor becomes that of power (P):

P = I² × R

You’ll note the only difference between the formula for determining power and that of determining Joules is the time component. The time factor in heating becomes readily apparent in any device that gets hot when an electric current flows through it: its temperature rises as time passes.