Hydroprocessing Technology

IsoTherming® Hydroprocessing Technology


The fundamental principle of the IsoTherming® technology is the ability to provide the hydrogen necessary for the chemical reactions using a liquid stream rather than a recycle gas system. The reactor feed is saturated with hydrogen, which eliminates the need for a recycle gas compressor and amine absorber. To satisfy hydrogen requirements within the reactor, supplementary hydrogen can be added by means of an external liquid recycle stream or inter-bed hydrogen injection.


See How IsoTherming® Hydroprocessing Technology Works:

A unique hydroprocessing technology, products and services help refiners make cleaner fuel efficiently and cost-effectively. IsoTherming® Technology is suitable in grassroots or revamp applications. Watch our 3D video!

Cleaner Fuels and
Reduced Energy Consumption


The IsoTherming® Hydroprocessing Technology is a commercially proven flexible process that provides refiners worldwide with a more economical means to produce today’s cleaner transportation fuels. Implementing the IsoTherming technology enables refiners to produce high-quality, low-sulfur fuels compliant with local environmental regulations and provides decresed consumption and operating costs when compared with historical trickle bed hydroprocessing technologies. The proven reliability and operational flexibility of the IsoTherming® technology also enable refinery stability and have many unique and commercially proven advantages compared to trickle bed technologies.

Process Technology
Process Technology
Commercially proven IsoTherming® Hydroprocessing Technology for producing clean fuels with reduced CAPEX and significantly lower energy demand
Comprehensive services from Elessent experts for engineering, training and technical support for the life of the plant
Engineered equipment for best-in-class performance and reliability
Advanced catalyst portfolio designed to optimize IsoTherming® technology performance

Robustness, Reliability and Safety


The IsoTherming® technology is a safe and easy to operate process. Elimination of the recycle gas compressor, high pressure heat exchangers and vessels not only reduces the quantity of high pressure equipment from the system and therefore reduces plot space requirements, but also significantly reduces the hydrogen inventory in the hydroprocessing unit. The IsoTherming® technology is also commercially proven to recover quickly from process upsets without loss of catalyst activity.

Optimal Reactor Design


The types of hydroprocessing application, product specification and chemical hydrogen requirements dictate optimal reactor design considerations. These include, but are not limited to, the number of catalyst beds and recycle ratio.

The IsoTherming® reactor design is robust and has been commercially proven to successfully process fluctuating feedstocks. This flexibility offers refiners the ability to process a wide variety of feeds to maximize refinery profits.  

Applications of IsoTherming® Technology:

  • Grassroots and Revamp
  • Kerosene Hydrotreating
  • Transmix Hydrotreating
  • Diesel Hydrotreating
  • FCC Feed Hydrotreating
  • Mild Hydrocracking
  • Dewaxing
  • Gas-To-Liquid (GTL) Upgrading
  • Heavy Oil Upgrading
Optimal Reactor Design

Reduced Operating Expenses


By eliminating the hydrogen gas compressor and its ancillary recycle loop equipment, significant maintenance and operating cost savings can be realized. In addition, for feed types with highly exothermic reactions, the IsoTherming® process recovers the heat of reaction by recycling a portion of the hot reactor effluent back to the inlet of the reactor. This direct transfer of heat to the feed in turn reduces the fired heater duty. Furthermore, the IsoTherming® process does not require heating of large quantities of recycle gas in the charge heater, providing additional fuel gas consumption savings. Overall, the IsoTherming® technology, has consistently demonstrated a 30-60% utility savings over trickle bed technology including:

Reduced Operating Expenses

Capital Cost Advantages

Conventional Scheme


The IsoTherming® technology has demonstrated significant capital cost advantages. These advantages are particularly pronounced in hydroprocessing revamps and low hydrogen consumption applications.

Capital cost savings over 30% have been achieved; however, these are dependent upon the application under consideration and global economic factors. 

Conventional Scheme

IsoTherming® Technology


As mentioned, the IsoTherming® technology recovers the heat of reaction by recycling a portion of the hot hydrotreated product back to the inlet of the reactor. As such, the feed/effluent exchanger heat duty requirements are reduced, which contributes to a significant reduction in high pressure heat exchanger shells that are required when comparing to an equivalent trickle bed design. Furthermore, separation of hydrocarbon and gas in order to recover the recycle gas is not required with the IsoTherming® process.

Consequently, the IsoTherming® process does not necessitate high or low pressure separation vessels and air coolers for the reactor effluent before entering the stripper or fractionator. For projects with low hydrogen consumption, the ability to supply the hydrogen through feed saturation without requiring a recycle pump results in even fewer pieces of high pressure equipment.Resulting in lower capital costs. 

IsoTherming® Technology

For example, one refinery with a commercially operating IsoTherming® Diesel Hydrotreating unit experienced a four-hour power failure event. Within five hours of power returning to the unit, the reactor returned to stable operation, producing on-spec product at the same reactor temperature.

The benefit of quick recovery time for the IsoTherming® technology is achieved for a variety reasons. First, the hydrogen content within the reactor is limited by solubility, reducing the number of hydroprocessing chemical reactions, (and associated heat release) that could occur. Secondly, the liquid in the reactor functions as a heat sink for the exothermic chemical reactions which limits undesired temperature rise and eliminates any potential for runaway in the IsoTherming® reactor.

This rapid return to original operating conditions without any long-term damage demonstrates the IsoTherming® technology’s robustness and inherently safe operation compared to trickle bed technology. In contrast, the unit downtime could be days in a similar power failure event in a trickle bed unit in addition to the potential of experiencing a reactor runaway or catalyst deactivation.

Commercially Proven Expertise


Elessent Clean Technologies continuously optimizes its liquid-full reactor design and unit configuration to process increasingly severe feedstocks at a lower capital cost. We are also actively identifying and evaluating opportunities for the IsoTherming® technology in new and emerging markets and applications.

Elessent licenses the IsoTherming® technology and offers products and services that support its customers throughout the life of the unit. With 24 licensed commercial units worldwide, the IsoTherming® technology is an innovative and commercially proven technology that is changing the way refiners are looking at hydroprocessing.

Elessent Clean Technologies can work with you to assess and design a custom-configured solution for your hydroprocessing challenges while offering unmatched technical support from design, to startup throughout the life of your plant.  

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