Thursday, August 1, 2013

Mg Soleil Project-8

IV. Magnesium Smelting
4.1 Kohama Smelting Process
4.2 Solar Furnace Used by Experiment (Fig. 2)

4.1 Kohama Smelting Process
A Kohama smelting process uses a solar furnace to generate the smelting temperature of 1,200 degrees C.  It is essential to efficiently harvest solar energy.  Places suitable for the magnesium smelting are located in the sun-belt zone including the equator.  The best places are the deserts having seaside areas in the zone.  The solar energy density in the desert is significantly high. It is about 3kW/㎡, about 3 times higher than that in Japan. The quantity of solar energy is about 7.5 times or more than that in Japan. The area of about 70 km2 covers the total energy consumption of Japan.  It is clear that if we will have means to efficiently harvest solar energy, we will be free from restriction on the choosing of the sites at which the smelting plants are located.
Kohama smelting technology uses a solar furnace which reflects light energy on mirror surfaces and condenses the light energy at a target point to generate the smelting heat.  The light energy is directly converted into the smelting heat. There is no energy transformation from solar energy to another form of energy.

Little loss is generated during a process to generate heat by light energy.  The light to heat conversion efficiency is excellent, 70% or higher.  See “Quality of natural heats”. Page 4
The Kohama smelting process employs the well-known Pidgeon process for the smelting process.  The magnesium smelting process comes in two varieties, reduction process (Pidgeon process) and electrolytic process. The Pidgeon process is mainly used at present.  The main reason for this is that the electrolytic process is expensive.  At present, China exclusively (about 90%) supplies smelted magnesium materials to countries in the world.  The Pidgeon process is carried at 1,200 degrees C and using a ferro-silicon (reducing agent). The smelting temperature is produced by burning Koks, resulting in emission of a large amount of carbon dioxide gas.

There is no problem in securing the smelting temperature of 1,200 degrees C.  The University of Prof. Kohama has long utilized the solar furnace for material research. The solar furnace produced high temperature near to 4,000 degrees C. Use of the plane mirror, not the parabolic mirror, suffices for the reflecting mirror, to produce 1,200 degrees C. It was experimentally confirmed that the Kohama smelting process operated as intended. This will be described in detail in “4.2 Solar Furnace Used by Experiment (Fig. 2)” to be given later.   In the current Pidgeon process, a ferro silicon is used for the reducing agent.  The ferro silicon is produced by using electric energy.   This is not economical.  Solar energy may be used in place of expensive electric energy.  Another catalyst of a high quality may be developed, if necessary.  This is not a difficult work. 

Yabe smelting process:
There is another professor who is developing another new magnesium smelting process.  He is Prof. Yabe (Tokyo Institute of Technology).  The Yabe smelting process uses a proprietary solar pumped laser for generating a temperature required for smelting magnesium.  The solar pumped laser generates a temperature of 20,000 degrees C, which is high enough to smelt magnesium.  The solar pumped laser is under demonstration test.  For details, please ask PEGASOS ELECTRA Co. Ltd. Prof. Yabe describes the basic concept of the "Mg soleil project" for realizing the “sustainable society” in "Magnesium Civilization", written by Prof. Yabe and Yamaji, published from PHP Shinsho. The Kohama project is somewhat different from the Yabe project. The difference resides in the smelting process. The Yabe smelting process uses the solar pumped laser, while the Kohama smelting process uses the solar furnace. 

4.2 Solar Furnace Used by Experiment (Fig. 2)
1.5m parabola mirror (search light used by Battleship YAMATO),
* Heliostat mirror
* Furnace core
* Smelted Mg
* Shell
Photograph-1 (Fig. 2)
Photograph-2 page 5 & 6

The heliostat tracking system using parabolic mirror elements was used in the experiment.
Magnesium-contained materials, reducing agents and heat sources, which were used in the experiment, are:
A. Magnesium-contained materials:
* Dolomite (from mine)
* Magnesium oxide (from final resultant material after use)
* magnesium hydroxide (from used generator)
* magnesium chloride
* magnesium chloride (seawater)
B Reducing agent:
* ferro-silicon (Pidgeon process)
* new carbon material
C. Heat source:
Heat source experiments were successfully conducted. Solar heat and electric furnace heat were used.
* Solar heat
* Biomass heat
* Waste heat from factory

A paper# describes the solar furnace that is currently used by Tohoku University. The solar furnace is of the heliostat type. The rotational parabolic mirror (diameter = 10 m, focal length = 3.2 m) is fixed. The heliostat is constructed such that seven mirror bands each consisting of plane mirrors are arranged one on another. The heliostat traces sunlight and applies solar energy concentrically to the target area. The computer controls the tracing operation of the heliostat. The temperature reached 3,727 degrees C at the target area. The solar furnace is installed at Research Institute for Scientific Measurements, Tohoku University.

# "Effects of the Miyagi-Earthquake on a Large Solar Furnace (Minor Special Issue on the Alternative Energy Technologies)"

DESERTEC project:
The project now progresses. Solar energy is condensed into thermal energy in the desert (Sahara Desert) being rich in solar energy.  The thermal energy generates steam, which in turn drives the steam turbine generator.  The generated electric energy is transmitted to the EU countries, through low loss HVDC transmission lines (submarine cables laid in the Mediterranean Sea). The average distance is 1,500 km between the desert and the EC countries. 6,000 km is the distance from the desert to Japan. It is clear that application of the DDESERTEC method to Japan is impossible.  Long transmission lines construction, high cost, and large power loss are inevitable.

IV. マグネシウム精錬
4.1 Kohama精錬

4.2 実験に使用したマグネシウム精錬用太陽炉設備(Fig. 2)
Kohama精錬法は太陽炉を用い1,200℃の精錬温度を得る。太陽光エネルギーの効率的な収集が必要である。精練所に適する場所は赤道付近のサンベルト地帯にある。この地帯の臨海地を持つ砂漠が最適だ。砂漠での太陽光のエネルギー密度は非常に高い。日本の3倍(約3kW/㎡)。日射量は約7.5倍。 日本の全消費エネルギーを約70㎞2の面積で賄える。太陽光の集光効率の高い手段ができれば、精錬所設置場所の選択の制約が緩和される。明らかである。
Prof. Kohamaの精錬では太陽炉を用い、光を鏡面で反射し集光し、それを熱源に直接利用している。太陽炉を用いた場合、太陽光を直接熱源に使用する。他のエネルギー形態への変換がない。光で熱を発生させる過程でのロスがほとんどない。その変換効率は70% 以上で圧倒的だ。See 「自然界で得られ熱の質」、page 4。
精錬には旧来のピジョンprocessを用いている。マグネシウム精錬には還元法(ピジョン法)と電解法がある。現在、ピジョン法が主流となっている。電解法は電気のコストが高いがその主な理由である。中国がピジョン法を採用しマグネシウムを世界にほぼ独占的に (90%前後) 供給している。ピジョン法では、1,200 ℃の温度とフェロシリコン(還元剤)を用いて還元が行われる。現在使用されているピジョン法ではコークスを燃やし、この高温を得ている。大量の炭酸ガスの発生は避けられない。
このprocessで必要とされる1,200 ℃の精錬温度の確保は全く問題がない。太陽炉については、Prof. Kohamaの大学は金属物性研究で古い実績を持っている。4,000 ℃近い温度を出している。1,200 ℃の温度を得るには反射鏡は平面鏡構成で十分であるとしている。
Kohama 精錬法はlabでその成功を確認してある。この実験で用いた設備を「実験に使用したマグネシウム精錬用太陽炉設備(Fig. 2)」に後述してある。

Yabe 精錬法:
今、別の角度から新しいマグネシウム精錬法を開発している学者がいる。Prof. Yabe (Tokyo Institute of Technology) だ。Yabe精錬法は独自の太陽光励起レーザー(solar pumped laser)を用いている。20,000℃の高温を得ている。これを用いて精錬に必要な温度を得ている。この太陽光励起レーザーは現在実証試験中。詳しくは、 (株)ペガソス・エレクトラ (PEGASOS ELECTRA Co. Ltd. ) にお問い合わせ願いたい。Prof. Yabeは「マグネシウム文明論」 (東工大の矢部孝・山路達也著, PHP新書)でマグネシウム循環社会の考え方を示している。Prof. Yabeのマグネシウム循環社会はPro. Kohamaのそれとはその実行の手法で少し違う。主な違いの一つがMgの精錬法である。

4.2 実験に使用したマグネシウム精錬用太陽炉設備(Fig. 2)
パラボラ鏡: 1.5m parabola mirror (戦艦大和の探照灯)
ヘリオスタッド: heliostat mirror
炉心: furnace core
精錬Mg: smelted Mg
Photograph-1 (Fig. 2)
Photograph-2 page 5 & 6
* ドロマイト(鉱山から)
* 酸化 Mg(使用済み最終酸化物から)
* 水酸化 Mg(使用済み発電器から)
* 塩化 Mg(海水から)
B. 還元剤:
* フェロシリコン(ピジョン法)
* 新炭素材料
C. 熱源:
* 太陽熱
* バイオマス熱
* 工場排熱

# "Effects of the Miyagi-Earthquake on a Large Solar Furnace  (Minor Special Issue on the Alternative Energy Technologies)"

DESERTEC project:
太陽光エネルギーの密度の高い砂漠で行われる。発電した電力を送電線(地中海に海底ケーブルを敷設)介してEU 諸国に送電する。平均距離 1,500kmである。DDESERTEC手法の日本へ適用は不可能。ここから日本への距離は6, 000kmである。


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