Nippon Steel & Sumikin Engineering Co., Ltd.

Keita Suzumura

Kazuhiro Takahashi

Hideki Fujii

Akira Kawakami

Akihiro Itoh

Teruhiko Hayashi

Masayuki Igarashi

Provided is a multiplex pipe and a system for recovering steam from a geothermal well, which are capable of solving all of the various problems with a neutralization pipe prepared by painting or the like of an alkali-resistant coating on the inner face of an acid-resistant single pipe. A multiplex pipethat is configured to recover steam from a geothermal well GT, includes: a casing pipelocated outside; and a duplex pipethat is slidable relative to the casing pipein the casing pipe, and has a first gapwith an inner face of the casing pipe, the duplex pipe including an outer pipehaving acid-resistance and an inner pipehaving alkali-resistance, the outer pipeand the inner pipedefining a second gaptherebetween. An alkali solution is injected to acid hot-water stored in an acid geothermal well GT via a hollowof the inner pipeto neutralize the acid hot-water, and the neutralized hot-water V is allowed to spout to the ground via the first gap, thus recovering flashing steam.

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Tokyo, Japan

Keita Suzumura