Multiplex pipe and system for recovering steam from geothermal wells

摘要

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 pipe 10 that is configured to recover steam from a geothermal well GT, includes: a casing pipe 1 located outside; and a duplex pipe 4 that is slidable relative to the casing pipe 1 in the casing pipe 1, and has a first gap 5 with an inner face of the casing pipe 1, the duplex pipe including an outer pipe 2 having acid-resistance and an inner pipe 3 having alkali-resistance, the outer pipe 2 and the inner pipe 3 defining a second gap 6 therebetween. An alkali solution is injected to acid hot-water stored in an acid geothermal well GT via a hollow 7 of the inner pipe 3 to neutralize the acid hot-water, and the neutralized hot-water V is allowed to spout to the ground via the first gap 5, thus recovering flashing steam.