Introduction
Hydrotreated vegetable oil, HVO for short, is a renewable fuel. It is also referred to as green diesel or hydro processed esters and fatty acids (HEFA), and is an important part of the global transition to lesser fossil fuel use, cleaner air, and controlled emissions.
Beyond reducing the use of fossil fuels, HVO also recycles waste streams. Since it has properties similar to fossil diesel, it can be used in existing diesel engines without blending limitations – this means that convincing consumers to make the switch is a lot easier than it would be with other renewable energy sources.
Compared to fossil diesel, HVO offers a cleaner and more consistent fuel profile. It has a higher cetane number, negligible sulphur content, and is free from aromatic hydrocarbons and oxygen, resulting in more efficient combustion and lower regulated emissions while remaining fully compatible with existing diesel infrastructure.
All in all, HVO is a great substitute for non-renewable fuels, even offering some benefits over other renewable fuels. So, producing HVO is a great decision, one that will stand the test of time as fossil fuels deplete and the climate gets increasingly unpredictable.
Before you can produce consumer-ready HVO, though, you need to pretreat your feedstock.
Your HVO pretreatment system must be safe, efficient, reliable, flexible, and sustainable. So, that’s what we’re going to explore in this blog series: how to plan your HVO pretreatment plant.
As always, let’s start at the very beginning.
Why do we even need HVO?
To fight against global warming, we have no choice but to reduce fossil fuel use. As is the objective of the European Commission’s “Fit for 55” policy and the Renewable Energy Directive (RED) II, the continent wants to reduce net greenhouse gas emissions by at least 55% by 2030 compared to 1990 levels.
HVO is part of the answer. The questions? How do we reduce the use of fossil fuels? How do we better recycle waste streams?
The need for the HVO pretreatment process.
Some of the feedstocks used to produce HVO have naturally occurring or commonly found impurities. Insoluble solid impurities, chlorides, polyethylene, metals, proteins, phospholipids, moisture, free fatty acids, and other unwanted compounds.
Using your feedstocks without removing the impurities present in them compromises the quality and yield of HVO produced. It also harms your equipment and reduces the lifespan of your catalyst.
The need for the HVO pretreatment process also arises from the types of feedstocks used. Traditionally, a wide variety of triglyceride- and fatty acid-containing raw materials have been used in HVO production. Think vegetable oils, animal tallow, waste and used cooking oils (UCO). Nowadays, in a bid towards greater sustainability and to avoid the food-vs-fuel fight for certain resources, HVO producers are also increasingly using alternative feedstocks. Think non-food-grade vegetable oils, sludge palm oil mill effluent (POME), distiller's corn oil, and low-quality animal fats. Even byproducts from oil refining, like oil recovered from spent bleaching earth, fatty-acid distillates, distillation pitches, acid oils from soap stock, and even non-glyceride compounds are being used to produce HVO.
All of these alternative feedstocks offer creative solutions to problems of limited resources. But they also present different challenges in terms of impurities. That’s why the HVO pretreatment process is an integral part of the overall HVO production process. It enables you, as an HVO producer, to leverage unconventional feedstocks to generate greener, cleaner, and recycled energy.
Selecting an HVO pretreatment plant manufacturer.
Setting up an HVO pretreatment plant isn’t a solitary endeavour. You must partner up with an experienced HVO pretreatment plant manufacturer to help you plan, design, build, operate, and maintain the facility.
The best HVO pretreatment plant manufacturers typically originate from the oils and fats industries. This is because the technologies used for HVO pretreatment are very similar to those used for vegetable oil and fat refining for use in the food industry. Kumar Metal Industries is a good example of this: our 80 years of experience across the oilseeds and oils processing value chains have given us the expertise needed for the HVO pretreatment process. This is demonstrated not only by our diverse projects across the world but also our extensive portfolio of similar technologies.
This isn’t to say that there are no modifications to traditional processes. As HVO producers have begun diversifying their feedstocks, increasingly leaning towards low-quality feedstocks, we plant manufacturers also have to optimise our equipment and processes to clean these feedstocks. Our OM Innovation Centre is the home of such developments at Kumar, helping us meet evolving customer needs.
Regardless of which HVO pretreatment plant manufacturer you work with, there are some things you should look into before kicking off your project:
- Your plant manufacturer should be able to offer flexible pretreatment systems that can process a range of feedstocks so that your plant remains functional and efficient even as the raw material landscape evolves in the future.
- The HVO pretreatment system they offer should give you high yields of pretreated oils and fats.
- The HVO pretreatment system must also have minimal unplanned downtime so as not to interrupt your operations, timelines, and budgets.
- Your HVO pretreatment plant manufacturer must also support you with technologies for wastewater treatment and water recycling. This is an important part of maintaining safe and sustainable operations.
- No relationship with an equipment provider should end with a sale. Your plant manufacturer will ideally be able to support you with commissioning, maintenance, audits, and any other service you need through the lifecycle of your HVO pretreatment plant.
- In terms of process efficiency, the HVO pretreatment system your process engineering partner gives you must offer a long catalyst lifecycle, maximum energy efficiency, minimum utility waste, and as low an environmental footprint as possible.
Now that you have some background on hydrotreated vegetable oil, the need for HVO pretreatment, and what to look for in a process engineering partner, you’re ready to dive deeper into the process. In part two of this blog post, we’ll explore the specifics of the HVO pretreatment process, pretreatment plant features, and why an investment in the right HVO pretreatment system will stand the test of time in an evolving energy market. Stay tuned.
Today, the main markets for HVO are in Europe and the United States. Considering the policies we discussed in part one of this blog post, European demand for drop-in fuels like HVO and sustainable aviation fuel (SAF) is forecasted to increase significantly in coming years. This will all be the result of higher blending targets, new mandates for the aviation sector, and other such policy decisions. By 2030, it is estimated that the share of HVO in oil-based biofuel demand on the continent will increase to 35%.
Meanwhile, new markets in other parts of the world are also developing rapidly. In South Asia, biodiesel is the most common biofuel, but HVO is rapidly gaining ground.
All over the world, HVO production is predicted to exceed 20 million metric tonnes annually in a few years. So, it’s no surprise that industrial players are increasingly investing in the HVO pretreatment process.
In this part of this blog post, we’re going to explore the HVO pretreatment process, the equipment you’ll need, and the design considerations you should keep in mind. Even though you’ll have to work with an HVO pretreatment plant manufacturer, it always helps to understand the ins and outs of the process yourself. It helps you optimise your operations and make informed decisions throughout the lifecycle of your plant.
So, let’s dive right in.
The HVO pretreatment process
Every HVO production unit has quality requirements for feedstocks, usually set by the HVO technology provider. Pretreatment can help you meet these stringent quality requirements. The HVO pretreatment process also helps you protect your catalysts and equipment, increase their lifespan, and avoid operational problems. Most importantly, your HVO pretreatment system directly impacts the viability of your HVO plant because it determines whether (or the extent to which) a low-quality feedstock can be used.
The HVO pretreatment process involves physical refining as well as chemical refining. Step one? Degumming: acid degumming or enzymatic degumming. Then comes adsorption. If required, deacidification is also carried out.
All oils and fats contain gums or gum-like materials like phospholipids or phosphatides. Removing these impurities is critical as their presence, especially under high temperatures, can lead to loss of catalyst activity, catalyst pressure drops, and fouling of heat exchanger surfaces. The process of degumming is meant to eliminate these impurities – phospholipids, trace metals, and mineral salts.
Acid degumming treatment typically involves the use of citric or phosphoric acid. This addition of acid leads to a homogenous reaction with organic metal salts, making them water soluble.
Enzymatic degumming involves the use of enzymes as natural catalysts. They make phosphatides more water soluble.
Adsorption, dry pretreatment or bleaching, typically carried out using silica or bleaching earth/clay, is meant to further minimise contaminant levels. Not only does this stage remove residual phosphatides left after degumming, but it also reduces the metal content of your feedstock. The bleaching earth or adsorbent used in this process often cannot be recycled, though consumption of the material can be influenced by changing the oil flow. The best HVO pretreatment plant manufacturers help you optimise oil flow to minimise bleaching earth consumption.
While these processes are sufficient for the pretreatment of high-quality feedstocks like high-grade animal fats and vegetable oil, low-quality feedstocks may need additional steps. For instance, additional bleaching to eliminate polyethylene and plastic residues.
Chlorides, if present in the feedstock, are removed by water washing. Polyethylene, if present in the feedstock, is removed via crystallization and filtration. Fatty acids, if they need to be removed to eliminate corrosion risks, can be eliminated through steam stripping the feedstock in a vacuum.
Some poor-quality feedstocks may also need additional steps prior to the standard HVO pretreatment process. This would involve prefiltration to eliminate solid impurities, polyethylene, and nitrogen components. Sometimes, this pre-pretreatment process would involve heat treatment to remove metals, acid oils, and phosphor-containing components.
While these additional steps may be the right option for some for their HVO pretreatment plant, others (especially those who use acid oils, trap grease, distillation pitches, and other low-quality feedstocks) may follow an alternative pretreatment process altogether. Such an alternative process generally comprises fat splitting and fatty acid distillation.
This alternative HVO pretreatment process does a good job of treating feedstocks with high contaminant levels, but it has the disadvantages of lower yields and higher CAPEX and OPEX compared to classic HVO pretreatment systems. This is why alternative processes have been limited to difficult feedstocks and low-capacity HVO plants.
HVO pretreatment plant design and equipment
Most HVO pretreatment plants house process line equipment like pressure leaf filters, centrifuges, heat exchangers, dynamic mixers, and process vessels and reactors. The typical construction material for valves, pipes, and machines is 316 or 304 stainless steel. Your equipment requirements, plant design, and layout will depend on multiple factors, including the feedstocks you’re working with and your by-product disposal processes.
At the end of the day, the HVO pretreatment system that works for someone else may not be the one that works best for you. Every HVO pretreatment plant is unique, with its own feedstock selection, processing capacity, budget, and other constraints. Planning your HVO pretreatment plant well means identifying the possibilities and constraints of your specific situation and finding the equipment, space, and processes that suit them.
At Kumar, we’re engineering sustainable solutions that align with our customers’ net-zero, waste reduction, and value addition goals. Given our core expertise in oilseed processing, HVO pretreatment is a natural addition to our process engineering services and an integral part of our sustainability endeavours.
We’ve already successfully delivered over 700 projects across more than 78 countries. 577+ customers are enjoying are promises of efficiency, resilience, and profitability. Do you want to be the next? Reach out to us today.
