What is a Fired Heater in a Refinery? For Dummies

Posted on
Did you know that ancient algae impact our lives to this day?  Read on to learn how decomposed carbon-based life becomes petroleum products with the help of fired heaters!
Oil comes from the remains of plankton and algae mixed with sediment on the ocean floor.
What is a fired heater in a refinery? Fired heaters, or process heaters, are important to refineries and petrochemical plants because they heat and vaporize the hydrocarbon fluids to create necessities like gasoline, diesel, and jet fuel.
As of January 2019, there are 135 petroleum refineries in the US.[1] In 2018, oil refinery capacity in the US amounted to 18.76 million barrels per day.[2]

Basic Fired Heater Functions

  1. Heat is produced by burning fuel
  2. This heat transfers to the process fluid in the tubes via conduction, radiation, and convection
  3. Combustion gases created by burning fuel exit the fired heater through a stack

Anatomy of a Fired Heater

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. Stack: exhaust chimney or vertical pipe through which flue gases escape the fired heater
  2. Convection Tubes: tubes located in the convection section
  3. Header Box: internally insulated compartment enclosing headers or manifolds
  4. Radiant Tubes: tubes located in the radiant section
  5. Casing: a metal shell, typically lined with refractory, enclosing the firebox and convection section
  6. Refractory Lining: heat-resistant lining; commonly made from castable or ceramic fiber
  7. Convection Section: area where hot flue gases leave the radiant section and circulate at high speed through a tube bundle
  8. Arch (or Bridgewall): location where flue gas exits the radiant section
  9. Radiant Section: area where tubes are directly heated by radiation from burner flames
  10. Breeching: transition where flue gas travels from the convection section to the stack
  11. Finned Tube: specialized tube with protruding fins that increase surface area and heat absorption
  12. Corbels: refractory material used to direct flue gases onto tubes as it passes though the convection section
  13. Crossover: connecting piping between any two coil sections
  14. Shield Section/Shock Section: non-finned tubes that shield the convection section from direct radiation
Important terms:
Flue Gas: gas produced as a byproduct of combustion inside the fired heater
Draft: the negative pressure of the air and/or flue gas in the heater
Tubes/Coils: a continuous metal pipe that transports fluid through a fired heater

Understanding Heat Transfer

Fired heaters utilize all three heat transfer methods (conduction, convection, radiation).
pot explaining heat transfer
Radiation is the transfer of energy from a heat source to objects in its path through space. In fired heaters, this occurs when heat energy is absorbed by tubes exposed to flames in the radiant section.
Convection is the transfer of heat from one place to another via fluid movement, like gases flowing over process tubes in the convection section of the heater.
Finally, conduction is the transfer of heat via contact between two materials or moving from one section of an object to another. In a fired heater, conduction occurs when heat transfers from the tube walls to the fluid flowing inside.

Heater Styles

The temperature inside fired heaters can reach a toasty 2,200° F.
Heater and coil combinations vary by application, but cabin/box and cylindrical style are the main types of heaters. The main difference is the orientation of tubes in the radiant section. In a vertical cylindrical heater, the tubes are arranged vertically while a cabin heater’s tubes are usually horizontal.
The American Petroleum Institute (API) sets the industry standards for fired heater design, with aspects ranging from material selection to burner arrangement to efficiency protocols.

Draft Systems

There are several methods to supply air and remove flue gases based on the location of draft systems relative to the heater.
  • Natural draft: the airflow induced by negative pressure (i.e. a vacuum) in the heater relative to the pressure outside the heater. This requires no fans.
  • Forced Draft (FD): air is supplied by forced draft fans that “push” air for a greater heat release per burner.
  • Induced Draft (ID): fans “pull” air to remove flue gases and maintain negative pressure in the heater.
  • Balanced draft: forced draft fans supply air while induced draft fans expel flue gases in a dual-fan system.
Proper Flow of Process Fluid
Properly flowing fluid is critical for optimal performance. Problems like flame impingement (flames contact tube directly) and slow flow cause heat transfer issues and equipment damage.
Coking or fouling occurs when carbon deposits accumulate inside tubes, like plaque buildups in arteries. This buildup decreases the tube’s usable area, thus restricting flow and insulating the tube wall which leads to less heat transfer. Left uncorrected, buildup can cause tubes to rupture leading to fires and potentially dangerous situations.
Source: Primedia Workplace Learning – Furnaces

Conclusion

Fired heaters are very important to the refining process. Heat is produced via combustion and transferred to the crude oil by radiation, conduction, and convection. Heating and vaporizing separates oil into the products we use every day. Next time you drive a car or board a plane, remember that fired heaters enable us to convert algae into acceleration.
NEW FIRED HEATERS
[1] https://www.eia.gov/tools/faqs/faq.php?id=29&t=6
[2] https://www.statista.com/statistics/265273/oil-refinery-capacity-in-the-united-states/
Ask an expert
© 2024
Please fill out the form below and we will be in contact as soon as possible.
GET IN TOUCH
Name(Required)
This field is for validation purposes and should be left unchanged.
Please fill out the form below and we will be in contact as soon as possible.
GET IN TOUCH
Name(Required)
This field is for validation purposes and should be left unchanged.
ERWIN PLATVOET
As CTO of XRG, Erwin is a true innovator, whose career spans more than three decades in heat transfer and combustion industries. Erwin is a graduate of Twente University in the Netherlands with a MS in Chemical Engineering. Erwin has served the industry around the globe in a variety of roles including Research and Development Engineer, Cracking Furnace Specialist, and Director of Engineering, and now CTO. Erwin holds eight patents in fired heat transfer and emissions control technology, has published numerous papers, and co-authored the John Zink Combustion handbook and Industrial Combustion Testing book. Erwin has been an active member of the API 560 and API 535 subcommittees and taken an active role in revising these standards.
BAILEY HENDRIX
Bailey graduated from Oklahoma State University with a Bachelor of Science in Mechanical Engineering. Upon graduation, she joined the private sector as an Applications Engineer in Tulsa, OK at a local combustion company where she managed the sales activities for the process burner refining market. She quickly accelerated her career, becoming the Refining Account Manager responsible for all business development and sales of process burners in North and South America. Her strong leadership skills and interpersonal qualities led her to a position as the Western Hemisphere Sales Director for the process burner business, leading a group of sales engineers in the areas of new equipment, retrofits and burner management systems. Her financial and commercial acumen drives the success of XRG Technologies’ business development.
ALLEN BURRIS
Allen’s background includes 10 years of experience in designing and selling process burners. Allen is a graduate of Oklahoma State University with a BS in Mechanical Engineering and is a licensed professional mechanical engineer in the State of Oklahoma. His knowledge and superior customer focus led him to a career change to process design, custom-engineered fired heater sales, and associated sub-systems for the petrochemical, refining and NGL industries. With more than two decades of experience in the combustion and fired heater industry, Allen has what it takes to overcome challenges associated with complex projects and possesses.
TIM WEBSTER
With over 25 years of experience in the combustion industry, Tim brings a wealth of industry experience and technical expertise to XRG. Tim graduated with a Bachelor of Science in Mechanical Engineering from San Jose State University and received a Master of Engineering from the University of Wisconsin. Tim began his career engineering custom combustion systems for a wide range of applications including boilers, heaters, furnaces, kilns, and incinerators. Tim is a licensed professional mechanical engineer in the states of California, Texas, Louisiana and Oklahoma, has authored numerous articles and papers, and has co-authored several combustion handbooks.
matt martin
As the Lead Scientist at XRG, Matt has over 30 years of experience in the combustion industry. He specializes in CFD of fired equipment, including UOP platforming heaters, burners in process heaters, thermal oxidizers and flares with over 300 simulations of installed, field-proven equipment. Matt received a Bachelor of Science in Computer Science with a minor in Mathematics from the University of Tulsa. He has written numerous publications, is listed as inventor or co-inventor on 27 patents and was awarded the title of Honeywell Fellow in 2011 for technical excellence and leadership.
gina briggs
Gina is a native Oklahoman and attended the University of Tulsa, graduating with a BSBA in Accounting. She is a Certified Public Accountant and Chartered Global Management Accountant. Gina began her career with the Tulsa office of Deloitte Haskins and Sells, providing audit and tax services. Since leaving Deloitte, she has held CFO positions with privately held companies in the manufacturing, construction and distribution industries. In 2013, she began a consulting practice providing contract CFO services to companies, one of which was XRG and joined XRG as CFO in 2019. Gina has always enjoyed working in the small business arena, helping business owners to profitably grow and manage their businesses.