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Accurate gas measurements play an integral role in ensuring direct reduction iron (DRI) plants operate at the highest levels of efficiency while achieving low emissions targets. Our range of analytical solutions ensure effective results across the process.
Our experts explore the challenges of the direct iron reduction (DRI) process for steelmaking. Listen to discover how accurate gas analysis can support safety, process efficiency, and emissions monitoring.
KG: Hello everyone. Welcome to another episode of Servomex’s podcasts on our star processes and applications. I’m Karen Gargallo, business unit manager for Industrial Processes and Emissions. In this episode, we will be discussing the direct reduction iron process, so DRI. And I’m joined today by MinWoo Lim, who you should already be familiar with if you have listened to our podcasts on liquefied natural gas and on the ethylene dichloride process. And all these, of course, podcasts you can find on the expertise section of our website.
Our second guest today, who is a bit newer to our podcast recordings for Servomex, is one of our product managers. Keith Warren. I think we’ll give some, obviously, opportunity for MinWoo and Keith to introduce themselves. Please go ahead, we’ll start with you, MinWoo.
MWL: Hello everyone, I’m MinWoo Lim, applications development engineer in Asia. Thank you for inviting me to the DRI application podcast.
KW: And my name’s Keith Warren, I’m the product manager for Process Oxygen and Zirconia here at Servomex, based in the United Kingdom Technical Centre in Crowborough.
KG: Thank you. So DRI, or direct reduction iron, process… For those who are not familiar with the process, direct reduction of iron is when oxygen is removed from iron or other materials which contain iron. This reaction happens in the solid state. It is a reduction process; the reducing agents that are used are carbon monoxide and hydrogen.
These two components can come from either natural gas, syngas, or coal. Decades ago, the more traditional way of producing iron was utilizing a chemical reaction between iron oxide and carbon monoxide generated from heating coke in a blast furnace. However, since then, there are now more reliable and more productive processes to produce three different types of iron, cold, hot, and hot-briquetted iron.
So, with these three types of iron that I mentioned, MinWoo can you provide, obviously, some information on the differences between these and how they are produced?
MWL: Yep. In the DRI process there are three types of DRI: cold DRI, hot DRI, and hot-briquette iron. Cold DRI is that, after reduction, the DRI is cooled in the lower part of the shaft furnace, to about 50oC. This material is typically used in the nearby electric arc furnace and passivated to prevent any oxidation and loss of the metallization. Cold DRI is ideal for continuously charging to electric air furnaces.
Hot DRI is that DRI can be transported to an adjacent electric arc furnace at up to 650oC, to take advantage of the residual heat which allows steelmakers to increase the productivity and reduce production cost.
Last one is the hot-briquetted iron (HBI), which is the preferred DRI production for the merchant metallics market, because it is much denser than other DRI, which reduces the reoxidation rate and minimizes yield losses from briquettes.
HBI is made by compressing DRI, discharging it from the shaft furnace at over 650oC into pillow-shaped briquettes.
KG: Thanks MinWoo. With the name of the process, direct reduction, it is a reduction process. There are different reduction reactions that are involved when iron is produced, so Keith can you provide the different types of reactions, please?
KW: Yeah, principally there’s two reaction types in the direct iron reduction process. The first is where you can use hydrogen to remove the oxygen from the iron or by direct reduction where the hydrogen reacts to form a water vapor. And there’s also the ability to use carbon monoxide to remove oxygen from iron or where that will then reduce iron and the by-product of CO2. The hydrogen iron reduction technology is principally a new technology where you are using hydrogen instead of coal as a reducing agent, and that extracts the iron from iron ore.
The water is emitted instead of carbon dioxide during the steel production process, and this can significantly reduce the carbon impact of the process, because you are no longer producing CO2. Instead of the existing furnace as a melting furnace, a reduction reaction between the hydrogen iron ore occurs through a facility called a fluid reduction furnace to produce the iron. Low-carbon iron still has a disadvantage in that it is less economical, as the unit price of hydrogen is typically four times that of coal.
KG: So the use of hydrogen for reduction means that it will result in no carbon dioxide emissions, which is key in making the process cleaner. However, there’s also the consideration with costs, as you mentioned. So now that we know how iron can be produced in different types of reduction reactions, as with any reaction or process, they need to be controlled to be as safe and as efficient as possible and, to achieve this, the gases that are involved in the process need to be measured. Can you please highlight, MinWoo, some of the key measurement requirements in the DRI process?
MWL: The DRI process is a low carbon dioxide emission application they are making using virgin iron ore in the electric arc furnace. The iron ore is heated as it descends through the shaft furnace and oxygen is removed from the ore using the counter-flowing gases with high hydrogen and carbon monoxide content. This process requires accurate gas monitoring for efficient operation. The direct reduction iron process requires a variety of gas measurement points. Since natural gas is used in the feed gas for the shaft furnace, methane, which amount is required, and natural gas is converted to the reducing gas in liquid form in reformer, CO and carbon dioxide and water measurements are required.
The DRI process requires the multiple point of the methane and carbon monoxide and carbon dioxide and water measurement; the SpectraExact 2500 can be applied. In addition the point which the heat exchanger and cooling gas is supplied from the furnace requires an oxygen measurement, we will see an Oxy 1900 and OxyExact 2200.
KG: So you’ve mentioned, MinWoo, about making the process efficient, but we also have to consider the gases that are produced, from the DRI process, that are emitted to the atmosphere, to the environment. And of course, this is a major application for any process. So, with emissions monitoring, what would be the typical gases that would need to be considered from an emissions monitoring application?
MWL: Emissions monitoring is also an important part of the DRI process. The reaction between counterflow gases and iron oxide in the ore produce metal iron, and water vapor, and carbon dioxide. In addition, the process may generate nitrogen oxide as NOx, which must be continuously monitored to ensure environmental compliance. We can apply a SERVOPRO 4900 Multigas to the emission monitoring solution.
KG: Thank you MinWoo. You have mentioned, of course, one of Servomex’s products, the SERVOPRO 4900 Multigas, which can be used for emissions monitoring. So if we go back then to the products that can then be used for process control, Oxy 1900 and OxyExact 2200 were also mentioned. Keith, can you give a bit more information on the Oxy 1900 and OxyExact 2200, and other products in Servomex’s portfolio that can also be used in the DRI process?
KW: Principally, we have two products for the measurement of process oxygen which is the SERVOTOUGH Oxy 1900 and the SERVOTOUGH OxyExact 2200 products. Both products are of an industrial design and are able to be installed into a Zone 1, Class 1, Division 1 certification environment, so they’re very rugged and industrial analyzers which are ideally suited for this DRI application.
The products also have SIL2 hardware certification should that be required. Both my products are really optimized for safety and process control applications and they can both be incorporated into a measurement voting system, should that also be required. The Servomex SERVOTOUGH SpectraExact 2500 is a separate product that’s really optimized for measurements such as carbon monoxide, carbon dioxide, methane, and H2O measurements in DRI applications, so the two combined provide a perfect mix of analyzer products for this application.
The SpectraExact 2500 also has hazardous area certification and is of an industrial design suitable for DRI installations. Certification is Zone 2, and also it has a Zone 1 option as well using a purge system.
And, finally, we have our 4900 Multigas emissions analyzer, which is of a rack-mounted-type design, typically installed as part of a wider sampling system with sample conditioning, so that the emission samples can be presented to the analyzer in an optimal way. That analyzer can measure, typically, carbon monoxide, sulphur dioxide, NOx, and of course, oxygen. And this product has had a long history of being certified with TUV and MCERTS emissions approval. So, it’s a well-proven analyzer for emissions applications.
KG: So I think your last point said about emissions, but with the process control applications in DRI because of the use of carbon monoxide, hydrogen, definitely a consideration on having analyzers such as the Oxy 1900, the OxyExact 2200, and the SpectraExact 2500 series that are all certified for flammable samples such as CO and hydrogen in use for hazardous area installations.
These products are suitable for DRI, but then there must be some additional considerations that we need to keep in mind when, having a DRI process, we have products that are suitable for the different applications in a DRI process, but these are extractive analyzers, so suitable sampling systems must be designed and used to make, of course, the reliability of the whole measurement system very good. And what would be these considerations in the sampling system that we have to highlight, MinWoo?
MWL: Feed gas or reformer gas will require certification for the hazardous area, because it contains the flammable gas, such as methane. Therefore, not only measurement products, but also a heater and cooler and solenoid are included in the sampling system, when it needs to be installed in the flow with explosion proofing.
The measurement point such as the furnace also contains a higher level of moisture, so we should check the dew point and be careful not to condense in the cell. If customers have any questions regarding the DRI process and solution, please contact the Servomex team.
KG: We can, then, recap the DRI process and different reduction reactions and the products that can be used for DRI. So, discussing the applications and products in a dry process, we also have to look at what, of course, the motivations are with regards to the production of the DRI. Can you please give a bit more background on this, Keith?
KW: Yeah, there’s some real common challenges in the iron industry generally in that there are no new blast furnaces being constructed currently really due to the environmental pollution and emission issues that the old-style blast furnaces had. So, direct iron reduction, obviously, is potentially a much cleaner process by using the DRI process. However, of course up to now, really, the process has used either carbon monoxide or a syngas containing carbon monoxide and typically hydrogen, that’s being produced from natural gas as the reduction gas.
But, of course, that in itself creates CO2 as a by-product of the process, and with the new change in global emissions, the CO2 has its own pollution issues, in that there’s obviously drives to go down the carbon capture route of the process, so that you actually capture the CO2 that you’ve generated from the process and are able to then store it, or reuse that carbon dioxide. Or, alternatively, of course, companies are looking at ways that they can operate the DRI process without generating so much (or ideally no) CO2 from the process, and to do that they would need to use a different reducing gas.
Typically hydrogen is being looked at as that reducing gas, which will then obviously reduce the CO2 emissions considerably in the process, as your only real emission of note would be water vapor, H2O. Of course, in order to use hydrogen in your direct iron process, it’s necessary to have a source of hydrogen fuel supplied for the process at the volumes required, and so companies have got to look at the requirements for potentially on-site generation of hydrogen to supply the process. And that obviously, ideally for a perfect low-carbon application, would be the generation of green hydrogen locally to the DRI facility. So, hydrogen has been a gas that’s been looked at as a clean alternative for the DRI process in the future.
KG: Thanks, Keith. So, good to know a bit more background on the current status of the DRI market. We know, of course, that the use of iron is quite important, you know, producing steel, which is the world’s most important material in terms of construction. And it’s also very good to note that more energy efficient, cleaner DRI processes are being developed.
So thank you, Keith and MinWoo, for your time and contribution. And thank you for all listeners to this episode of our podcast on DRI. Please visit our website, servomex.com. Click on the expertise section to find out more about the DRI process. There’s a lot of information supplied on the website and also podcasts on our other star processes such as LNG, ethylene oxide, and the EDC process. Again, thank you for your time and bye for now.
KW: Thank you.
MWL: Thank you.
The Midrex DRI process is a low-carbon-dioxide-emission application in steelmaking using virgin iron ore in an electric arc furnace. The iron ore is heated as it descends through a shaft furnace, and oxygen (O2) is removed from the ore using counterflowing gases with a high hydrogen and carbon monoxide content. This process requires accurate gas monitoring for efficient operation.
Emissions monitoring is also an important part of the DRI process. The reaction between the counterflow gases and iron oxide in the ore produce metallic iron, water vapor, and carbon dioxide (CO2). In addition, the process may generate oxides of nitrogen (NOx) which must be continuously monitored to ensure environmental compliance.
Servomex supplies the SERVOTOUGH Oxy 1900 for essential O2 monitoring in the DRI process. This is an industry-leading Paramagnetic O2 analyzer designed for hazardous areas. This is supported by the highly flexible SERVOTOUGH SpectraExact 2500 photometric analyzer for the other measurements. The SERVOPRO 4900 Multigas and SERVOPRO NOx analyzers provide required continuous emissions monitoring.
With wide experience in supplying solutions to industries using the direct reduction iron process, we are able to deliver the analyzers and sampling systems required for effective analysis.
As global experts in gas analysis, we have the extensive applications knowledge to provide the best support for DRI processes, with a range of technologies to meet measurement requirements.
Our comprehensive analytical solutions provide the best-fit technologies for each measurement point in the process, delivering accurate, reliable results that support process efficiency and emissions monitoring.
All our analyzers and systems are backed by a worldwide network of trained service engineers, ensuring reliable operation at a peak level of performance.
Karen leads the Industrial Process and Emissions Business Unit in providing solutions which support our customers as they overcome the challenges of making their processes safer, cleaner, and more efficient.
Karen Gargallo, Business Unit Manager, IP&E
Responsible for managing our oxygen analyzers in the Industrial Process & Emissions sector, Keith has been working with gas analysis solutions for more than 20 years, 12 of them at Servomex.
Keith Warren, Product Manager
Leading the life-cycle management of our Spectroscopic analyzer range, Rhys is responsible for the development of the markets they serve, and the strategic growth of those technologies.
Rhys Jenkins, IP&E Product Manager, Spectroscopic Analyzers
Overseeing the business development operations of our Industrial Process & Emissions team in China, Huiyu leads our pursuit of large international projects.
Huiyu Guan, Business Development Manager, IP&E, China
Stephen is responsible for managing the lifecycle of new Servomex Products, specifically, the introduction of new technologies into Servomex Analyzers. As STEM Team Leader he also coordinates the internal and external STEM program.
Stephen Firth, Product Manager- Strategic Projects
The high-specification OxyExact 2200 O2 analyzer offers an unrivaled combination of precision, flexibility and performance for optimum process and safety control.
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