• IHI Corporation

Hydrogen energy, now attracting attention in the world. In addition to hydrogen, IHI has focused on ammonia which is a hydrogen carrier easier to transport and store than hydrogen, and accelerated a study on hydrogen energy utilization technologies such as co-combustion technology enabling the stable combustion of ammonia, and high efficiency hydrogen production technology from renewable energy. IHI's technologies make it possible to take another step closer to energy decarbonization.

• IHI Transport Machinery Co., Ltd.

Compared to conventionally used coal (high-rank coal), low-rank coal has a lower calorific value, but it is less expensive. One effect expected from the shut-down of nuclear power plants following the Great East Japan Earthquake of 2011 was rising demand for low-rank coal, but low-rank coal has the disadvantageous characteristic of being prone to heat build-up during storage. The "coal storage facility heating prediction system" developed by IHI Transport Machinery Co., Ltd. (IUK) is capable of (1) simulating the heat generated in coal considering the kind of coal, (2) comprehensive assessing of the analysis results, (3) advising on the management and planning of coal storage including facilities.

• Niigata Power Systems Co., Ltd.

Niigata Power Systems Co., Ltd. has successfully halved the costs and shortened the lead time to one third as well as improved production capacity while getting rid of conventional manufacturing practices. To this end, its production division reviewed the upstream design to standardize and visualize processes and eliminate waste work.

• KATO Shoji, SAITO Toshiyuki

Niigata Power Systems Co., Ltd. has added the V28AHX to its NIIGATA 28AHX Series, the bestselling engine series which has sold over 200 units. The V28AHX offers an increased output range, completing a lineup of highefficiency engines with an output ranging from 2070 to 6660kW.

• CHOI Wonyoung, OMORI Daisuke, ITO Takamasa, TAKAHASHI Katsumi, TANAKA Akihiro

The spontaneous heating behavior of sub-bituminous coal stored in a 120-ton experimental silo was investigated. The temperature distribution in the coal bed and the oxygen concentration in the silo were measured. A heated zone formed in the central part of the coal bed, and its maximum temperature reached over 45°C during storage. After nitrogen entered the silo, the heating of the coal bed was suppressed due to the resultant reduction in oxygen concentration in the silo. The heating behavior was numerically analyzed using a computational fluid dynamics (CFD) model that took into account gas flow through the coal bed and heat generated by oxygen being absorbed into coal particles. The numerical temperature distribution in the coal bed was consistent with the experimental results.

• ONIKI Toshiro, NABEMOTO Toyonobu, FUKUI Toshiki

The development of technologies for treating nuclear waste generated by nuclear power plants and reprocessing plants during their operation or decommissioning is underway both in Japan and abroad. Of the many types of treatment technologies that have been developed, vitrification technology is attracting attention as being the most promising technology for converting such waste into a stable state. As a brief review of technical developments aimed at reducing nuclear waste and finding a solution to the final disposal issue, this paper describes approaches to completing the development of vitrification technology in Japan, including IHI's activities.

• KAWAKUBO Tomoki, UNNO Masaru, NUMAKURA Ryusuke, SHIMOHARA Naoto,KOTANI Koji

A turbo-compressor is a type of multi-stage centrifugal compressor that is often used in factories to boost or compress gaseous fluids. By making its overall size more compact than ever before, it is possible to reduce the initial costs associated with the installation of a new compressor. In order to realize a more compact compressor, the same amount of fluid must be processed in a smaller space; that is, a higher flow capacity will be required for each of the constituent compressor stages. However, squeezing fluid forcibly into a smaller space will result in a higher through-flow velocity and/or a more acute flow turning, which inevitably makes it difficult to maintain or improve the stage efficiency. Moreover, raising the height or reducing the thickness of the blades for the purpose of widening the cross-section of the passage may result in an increase in blade stress and/or a reduction in the blade's natural frequency. This report describes the efforts made to overcome the above-mentioned technical challenges that occurred in the development of a high-flow compressor stage that is intended to be applied in integrally-geared turbo-compressors.

• ZHENG Xinqian, LIN Yun, KAWAKUBO Tomoki, TAMAKI Hideaki

In recent years, higher performance, including higher flow capacities and pressure ratios, is required of the centrifugal compressors used in turbochargers, while compactness is also required in views of improved installability and lower costs. Due to these mutually conflicting requirements, the internal flow velocity tends to increase and the circumferential pressure distortion generated by the non-axisymmetric geometric nature of the discharge scroll gets harsher, and both of these result in the reduction of the stable operating range. In an attempt to overcome this difficulty, a vaneless diffuser with a non-axisymmetric passage geometry has been developed which can suppress the circumferential pressure distortion and consequently retard the occurrence of the destabilizing flow conditions. Performance tests of both the axisymmetric and the non-axisymmetric diffusers confirmed that the non-axisymmetric design can extend the stable flow range by 28% over the conventional axisymmetric design.