KIOGE-2024
How Can We Make Industry More Climate-friendly?
Hydrogen for industry is the climate-friendly way to make industrial processes more sustainable. The industry requires large quantities of hydrogen. Unfortunately, the current methods of generating hydrogen emit the greenhouse gas carbon dioxide. To generate hydrogen in a more climate-friendly manner we need highly specialised pumps.
In 2022 KSB supplied pumps and valves for a project of construction of a 24 MW electrolysis plant in Norway for producing green hydrogen as a feedstock for green ammonia. The necessary hydrogen is to be generated by means of electrolysis using hydropower. The scope of supply for this project includes standardised chemical pumps of the MegaCPK type series with all wetted parts made of high-quality duplex steels, and SISTO-RSK swing check valves equipped with a special coating. Prior successful experience of supply to the projects of construction of polypropylene plants, air separators and carbon dioxide separators became the key reason why KSB won this order.
Without hydrogen not much would be happening in industry: Hydrogen is needed for producing ammonia, for example, which is a base material for fertiliser.
Hydrogen is also required for producing methyl alcohol, the source material for chemicals such as formaldehyde or acetic acid. Crude oil refineries use it to refine mineral oil or for producing synthetic fuels.
Using hydrogen would also be an option for the steel industry to produce pig iron without any carbon dioxide emissions. This sector is responsible for the lion’s share of greenhouse gas emissions in industry.
Unfortunately, the generation of hydrogen also produces large quantities of carbon dioxide. It escapes to atmosphere and further drives global warming. What is the reason for so much CO2 being released during hydrogen production and how to evoid this negative effect?
About 95 percent of the hydrogen used in industry today is so-called «grey» hydrogen. It is gained from natural gas – chemically referred to as «methane» – using the process of steam methane reforming (SMR) or more efficient method of autothermal reforming (ATR). However, both these methods produce large quantities of carbon dioxide – about ten tonnes for every tonne of hydrogen generated.
The most sustainable way of generating hydrogen is by electrolysis. In this method an electrolyser splits water (H2 O) with the help of electric power into its elements: hydrogen (H2 ) and oxygen (O2 ). If the power used is from renewable sources the hydrogen generated this way is climate neutral. This is why it is called «green hydrogen».
Green hydrogen would be the ideal solution. Unfortunately, it is not available in sufficient quantities – and it won’t be soon either.
BLUE HYDROGEN IS A REALISTIC INTERIM SOLUTION
Until electrolysis processes for hydrogen generation have become more advanced and sufficient capacities are available for producing green hydrogen, «blue» hydrogen could serve as an interim solution. It is generated in the same way as conventional grey hydrogen by natural gas steam reforming. The difference is that the CO2 produced in this process is separated using CCS (carbon capture and storage) technology instead of being released into the atmosphere. The CO2 can then be transported on board a vessel or through a pipeline to underground storage facilities.
Depleted gas and oil reservoirs in the North Sea could be used for storing CO2. Here, CO2 could be pressurised and pressed into deep, porous sandstone layers, where it will react with the rock and miner alise in the long term. A cover layer of rocks with a thickness of several kilometres will make sure the carbon dioxide cannot escape from the storage reservoirs.
Blue hydrogen, which is available to the industry within a short timeframe, has benefitted from the many years of experience with CO2 storage, as illustrated by the Sleipner project, 250 kilometres off the Norwegian coast.
This technology could serve as an interim solution to reach the climate targets faster in parallel to the infrastructure for green hydrogen being developed.
Studies have shown that blue hydrogen can be almost as sustainable as green hydrogen as long as two conditions are met: First, the technology used for reforming the natural gas has to enable separation of more than 90 percent of the carbon dioxide.
Secondly, leakage must be prevented when handling and transporting natural gas. Because of its high global warming potential, not more than one percent of the methane used must be emitted.
According to data of the International Energy Agency, this is already the case in countries such as Norway, the United Kingdom and the Netherlands. Under these conditions, the generation of blue hydrogen produces 2 to 3.5 kilograms of CO2 equivalent per kilogram of hydrogen – values that are comparable to those of green hydrogen production.
KSB DRAWS ON DECADES OF EXPERIENCE IN GENERATING HYDROGEN
For producing hydrogen as well as for collecting, transporting and storing CO2 highly specialised pumps and valves are needed. They not only handle the pressurised liquefied carbon dioxide, but they also pump absorbers such as amine solutions, which bind the gas – like sparkling water. In addition, CCS systems require process water and contain numerous cooling circuits in which water is circulated. Leakage has to be prevented and the systems have to be corrosion resistant as dissolved carbon dioxide and amine solutions can be corrosive. It is further important to prevent low pressure zones from forming in the systems in which carbon dioxide would change from the liquid to the gaseous state. This requires a lot of practical experience.
KSB has got the advantage of knowing the chemical industry processes very well. We look back on decades of experience in generating grey hydrogen. This also benefits us when producing blue hydrogen. At a temporary test stand in Frankenthal we investigated the factors influencing the aggregation state of carbon dioxide in detail. This enabled us to find the most efficient pump and the right operating range for the corresponding task in the CCS process and to advise our customers accordingly.
KSB unique know-how in pump technology and global cooperation make it possible for the company to realize blue decarbonisation projects today.
VERSATILE PUMPS FOR EXTREME CONDITIONS IN CCS SYSTEMS
In smaller systems that process between 10,000 and 100,000 tonnes of CO2 per year, industrial companies frequently employ the Magnochem seal-less volute casing pump.
Its rotating shaft does not pass through the casing and therefore does not need to be sealed off, thus ruling out the risk of leakage at the seal. A magnetic coupling transmits the torque from the motor to the inside of the pump casing without any contact. This means the standardised chemical pump is hermetically sealed, providing protection against leakage.
The pump meets the highest of quality standards to ISO 5199. It is available in a large range of material variants. Its robust design is suitable for up to 40 bar. A version to API 685 is also on offer. Its great choice of hydraulic system sizes and magnetic couplings offers maximum flexibility.
The patented containment shrouds are extremely resistant to corrosion and do not produce eddy currents when a magnetic field passes through it. Undesirable heat losses which would reduce output and compromise pump efficiency are thus eliminated.
In addition, to improve safety and expand the application range of Magnochem pumps KSB introduces the newest patented MagnoProtect containment shroud which combines the very latest additive manufacturing technology and innovative safety provided by two static leakage barriers. This technology is compatible with all existing Magnochem types enabling them to meet the requirements of industrial safety and operate at temperatures up to 400 °C and pressures up to 40 bar.
In large systems that process about a million tonnes of CO2 per year, pumps to industry standard API 610 / ISO 13709 are employed. For example, multistage between-bearings pumps such as CHTR (type BB5).
This pump set is designed with bearings on both sides of the impellers to distribute the load equally at high pressure or larger flow rates. It has been developed with maximum reliability and ease of maintenance in mind: An optimised design balances out any pressure differences and reduces the axial thrust along the shaft, which is one of the main factors affecting the wear of bearings and seals.
Strong rolling element bearings or segmental thrust bearings hold the impellers in axial position and absorb the remaining axial thrust. Mechanical seals and bearings can be serviced without the need to open the pump.
SAFE VALVES FOR OPTIMUM FLOW CONTROL
Valves are just as important as pumps for producing blue hydrogen. Many companies opt for double-offset butterfly valves with a plastomer seat, such as DANAÏS 150. Plastomer materials are chemically resistant, enhance sealing properties and reduce wear compared to conventional seat materials.
Often the users of CCS systems also employ cage-guided singleseated control valves, which are fitted with a single valve disc supported by a cage or frame. This type of valve is often used in industrial plants when precise control of a fluid flow is required.
For liquefying carbon dioxide, they use metal-seated butterfly valves made of stainless steel. The metal contact between the valve disc surface and the seat surface provides a tight shut-off and minimises the risk of leakage.