Heat transport analysis in a district heating system applying waste heat from GTHTR300, a commercial design of high-temperature gas-cooled reactor

商用高温ガス炉GTHTR300の廃熱を利用した地域熱供給システムの熱輸送解析

笠原 清司  ; 村田 哲也*; 上地 優; 寺田 敦彦  ; Yan, X. ; 稲垣 嘉之; 森 治嗣*

Kasahara, Seiji; Murata, Tetsuya*; Kamiji, Yu; Terada, Atsuhiko; Yan, X.; Inagaki, Yoshiyuki; Mori, Michitsugu*

熱電併給高温ガス炉GTHTR300の廃熱を利用した地域暖房・路面融雪システムの解析を行った。熱利用地域には豪雪地帯である札幌と石狩を想定した。GTHTR300と熱利用地域間で熱水を循環させる給熱配管、給熱配管から地域内の熱供給配管へ熱を伝える熱交換器、地域内の熱供給配管のモデル化による熱輸送解析を行った。給熱配管としては、二重管の方が単管と比べて熱ロスや埋設のための掘削面積が小さい点で有利であったものの、配管コストの不利を補うほどではなかった。年間で最大となる1月の熱需要をまかなうためには520-529MWの熱が必要となり、この時GTHTR300は3基、給熱配管は6ループ、熱交換器(長さ約90m)と地域熱供給配管は3,450基必要となった。地域熱供給配管における熱ロスが全ロスの80%-90%を占め、断熱材が全建設コストの90%以上に上ったため、経済的な熱供給を行うためには断熱層厚さや断熱性能の最適化が必要である。

A district heating system for household heating and road snow melting utilizing waste heat from GTHTR300, a heat-electricity cogeneration design of high temperature gas-cooled reactor, was analyzed. The application area was Sapporo and Ishikari, cities with heavy snowfall in northern Japan. The heat transport analyses were performed by modeling components to estimate heat supply profile; the secondary loops between the GTHTR300s and the heat-application area; heat exchangers connecting the secondary loops to the tertiary loops of the district-heating pipes; and the tertiary loops between the heat exchangers and houses and roads. Though double pipes for the secondary loops were advantageous for having less heat loss and a smaller excavation area, these advantages did not compensate for the higher construct cost of the pipes. To satisfy heat demand in the month of maximum requirement, 520-529 MW of heat were supplied by 3 GTHTR300s and delivered by 6 secondary loops, 3,450 heat exchangers about 90 m long, and 3,450 tertiary loops. Heat loss to the ground from the tertiary loops comprised 80%-90% of the heat loss. More than 90% of the construction cost went into thermal insulators. The thickness and properties of the thermal insulator must be reevaluated for economical heat delivery.