Gas mixer for next-generation pyrolysis reactors
Ceramic 3D printing revolutionizes the production of e-fuels
Description of the component:
The project of ExxonMobil R & E Co. and Keramik Innovation Berthold dealt with the development of a gas mixer. The mixer is a component of the new generation of chemical plants for the pyrolysis of hydrocarbon feedstocks. One of its many applications is the production of e-fuels.
The mixer is manufactured from aluminum oxide using ceramic FDM 3D printing. The filament used for this was produced by Keramik Innovation Berthold in cooperation with Krahn Ceramics GmbH.
The challenge:
The new generation of pyrolysis reactors operates at higher temperatures than their predecessors. In addition, a "heat wave" moves back and forth in the reactor. As a result, the components are permanently exposed to a temperature difference of up to 1,200 °C. This new process control makes it possible to reduce the size of the system by up to 40%. Despite the higher process temperatures, the new systems require less energy due to the reduction in size.
However, the use of technical ceramics is increasingly necessary. Honeycomb pipes are used to transport gas upstream and downstream of the mixing unit instead of metal pipes.
The weak point of the first test systems was the mixing unit. This consisted of a 25 cm high column of ceramic multi-hole disks. After a maximum of five days of operation, individual disks of the column failed due to cracks. The cause was identified as the thermal stress generated in the column. Simulation calculations at ExxonMobil showed that a massive reduction in the thickness of the mixing unit was the solution.
Solution:
A new mixing concept was jointly developed, which was achieved by a special forced guidance of the gas through the fine rods. This gas flow is achieved by offsetting the bars in each position. As a result, there are no free-flowing channels as with a normal screen structure. The smallest version of the resulting mixer has 702 such rods.
Traditional alternatives for ceramic production would be
- The extrusion of a ring, green machining of the 1404 holes and threading of 702 rods that are also extruded
- Production of four pressing tools and subsequent assembly before firing (= garnishing). In the process, 0.8 mm thick components have to be pressed, which causes considerable difficulties in handling.
The mixer is therefore a component that can only be produced cost-effectively using ceramic 3D printing.
Conclusion:
This mixer can be used by all users who require a homogeneous gas mixture in the smallest possible space.
It also impressively demonstrates that 3D-printed ceramics can be the most cost-effective solution for complex challenges thanks to the freedom they offer in component design. In the next stage of development, the mixer is planned as a resistance-heated version. This will enable the direct input of process energy.