Isothermal Refining by Organic Solvent Nanofiltration - ISOREF

Lead Research Organisation: Imperial College London
Department Name: Department of Chemical Engineering

Abstract

Crude oil refining is (after chemicals production) the second most energy intensive industry in advanced economies. For example, refining consumes 6% of the total energy used in the US. Current refinery technology is based on distillation for separation of the crude oil into fractions with varying molecular weights, followed by further reactions on some of these fractions (reforming, hydrotreating, cracking etc), which must then be further distilled. Distillation involves converting a large fraction of a liquid feed into a gas by boiling, so that compounds present in the feed can be separated by means of differences in their boiling points. In refining, distillation typically account for more than half of all the energy consumed, since the phase change on boiling requires significant energy input.

One way of avoiding this large energy consumption would be to carry out fractionation in the liquid phase via a membrane. If a mixture of hydrocarbons is pressed by pressure against a membrane, and the membrane is permeable to only some of the materials, then we can separate the molecules that pass through the membrane from those that do not. This avoids the large energy injections of evaporation or distillation. Theoretical calculations show that the energy required for concentrating a mixture by membrane separation is less than 5% of the energy associated with distillation.

Not surprisingly, people have been interested in using membranes to separate and concentrate liquids for some time. The majority of membrane separations to date are water based. A major success is in the area of desalination, where membranes are used to separate fresh water out of seawater. Membranes are not generally used for molecular separations in organic systems, because until recently there were few membranes stable in organic liquids. This has changed recently - research at Imperial College has developed membranes that are stable in most organic systems. These have been commercialised through an Imperial spin out company, Membrane Extraction Technology (MET) which was acquired by Evonik Industries on 1 March 2010. Evonik MET has made a substantial investment in a large scale membrane manufacturing facility in West London, delivering on the UK Government's vision for Manufacturing the Future.

In many cases the required separation cannot be achieved in a single pass through a membrane, because the membrane does not discriminate highly enough between the different molecules that are present. In these cases, to achieve the required separation, the liquid can be processed through membranes multiple times. This arrangement of membranes is known as a membrane cascade.

Given the advances that have been made in the development of membranes for organic systems and their application in membrane cascades, this project will research the use of membranes for refining crude oil. Membranes do not require boiling and condensation, and so can be operated at a single temperature. This will reduce the needs for heating and cooling, and so the associated heat losses. Thus we expect that isothermal refining with organic solvent nanofiltration membranes will significantly reduce the energy requirements for manufacturing fuels and lube products from crude oil.

The project will work with a synthetic clean crude, made up to simulate the key hydrocarbon components of a real material. Experimental and simulation work will be used to design a membrane cascade to separate the synthetic crude; this cascade design will then be assembled and operated to prove the concept. Further simulations will then estimate what energy savings would result if isothermal refining were employed with a real crude. The project will work closely with partner Shell Gobal Solutions, who are a major company in oil refining and refinery technology.

Planned Impact

The economic benefits of the research proposed are (i) the business around licensing the technology developed to refinery operators globally, production of the required membranes, and installation of the capital plant, and; (ii) energy savings by the refinery operator through using isothermal refining.

The separations research group at Imperial College has a strong demonstrated record in the commercialisation of membranes derived from its research. Evonik MET, based in West London, is the only dedicated manufacturing facility for organic solvent nanofiltration membranes in the world. The fundamental processes they use were developed at Imperial College with EPSRC research funding. Therefore the group has experience in the development of manufacturing processes and commercialisation of research.

If the proposal is successful, it will be the first step in a revolutionary new technology for crude oil refining. We estimate that distillation consumes some 300 MJ per barrel of crude, and that isothermal refining might reduce this by at least 150 MJ per barrel. A barrel contains around 6400 MJ and is worth around US$100 or £60; so our savings of 150MJ correspond to about 2% of a barrel or £1.20 per barrel. Global oil production is around 75 million barrels per day, or 27 billion barrels per year. Therefore potential impact is over £32 billion per annum. Realistically, technology penetration is unlikely to reach past 1% of oil refined in the next 10 years, and so a more realistic figure for savings is around £320 million per annum by 2024.

These economic benefits have parallel social benefits. The manufacture of the capital assets and membranes isothermal refining would require, creates high level and knowledge intensive employment, and improves the national accounts through exports achieved. The reduction in energy consumption has environmental benefits, reducing carbon dioxide emissions and making more efficient use of the finite resource which crude represents.

Publications

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Description AT THE OUTSET, WE BELIEVED THAT MEMBRANE TECHNOLOGY COULD REPLACE DISTILLATION AS A WAY OF SEPARATING MIXTURES OF MOLECULES, AS IT WOULD USE LESS ENERGY. OUR DETAILED ANALYSIS THROUGH EXPERIMENTS AND MODELLING, SUGGESTS THAT IN FACT A MEMBRANE PROCESS TO REPLACE BINARY DISTILLATION COULD BE HIGHLY COMPLEX AND MIGHT CONSUME EQUIVALENT ENERGY TO BINARY DISTILLATION.
Exploitation Route WE HAVE STARTED A FUNDED RESEARCH COLLABORATION WITH EXXON ENGINEERING IN THE US BASED ON OUR RESULTS, AND WILL TAKE THEM FORWARDS IN THIS FRAMEWORK.
Sectors Chemicals,Energy,Pharmaceuticals and Medical Biotechnology

 
Description WE HAVE USED THEM TO PINPOINT THAT MEMBRANES WILL BE MORE EFFECTIVE IN SAVING ENERGY WHEN APPLIED TO COMPLEX MIXTURES, THAN BINARY (TWO COMPONENT) MIXTURES WHICH REQUIRE HIGH PURITY. ADDITIONALLY, WE HAVE USED THIS GRANT TO SUPPORT OUR OUTREACH ACTIVITY. A subsequent application we made to EPSRC to continue this work was declined. However we have been successful in setting up a collaboration with ExxonMobil Research and Engineering, and Georgia Tech, funded by Exxon to continue and this has resulted in a paper in Science in 2020.
Sector Chemicals,Energy,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology
Impact Types Economic

 
Description Hydrocarbon production, refining, and chemical products and processes
Amount £400,000 (GBP)
Organisation ExxonMobil 
Sector Private
Country United States
Start 05/2018 
End 06/2020
 
Description Outreach Activity at The Imperial Festival, 28-29 April 2018 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact The College's annual Imperial Festival was held on 28-29 April 2018. It was freely open to the general public and included sessions for schools and alumni providing an opportunity to go behind-the-scenes and explore the latest research at Imperial College. The Festival included live interactive experiments, new technology demonstrations, in-depth talks, lab tours, musical and dance-based performances, and creative workshops within zones themed around Robots, Superbugs, Health & Body, the Future, and Energy and Environment. The Barrer Centre demonstrated a membrane system used to purify water and compared it directly with a coventional system based on water evaporation (ie boiling) and condensing. The energy requirement for the membrane system was significantly less than for the conventional system.
Year(s) Of Engagement Activity 2018
URL https://www.imperial.ac.uk/festival/