露天掘炭鉱における石炭地下ガス化試験

抄録

In our laboratory, fundamental tests on underground coal gasification (UCG) by using coal blocks were conducted for several years. Last year, a small scale field test on UCG was carried out at a part of developing area of Mikasa surface mine in Hokkaido.
At the field, two bore holes were drilled, one is incline bore hole and the other is vertical bore hole. The lengths of incline bore hole and vertical bore hole were about 5m and 1.4m, respectively. The vertical bore hole was used for an oxygen injection hole and ignition hole. The incline bore hole was used for a gas production hole. Some temperature sensors were installed around the incline bore hole to measure the temperature of around the production bore hole. AE sensors were also installed around the incline bore hole to estimate the gasification zone in the coal seam. Underground Coal Gasification (UCG) demands precise evaluation of the combustion area in the coal seam. Especially, the monitoring of fracture activity in the coal seam and around rock is important not only for efficient gas production but also for estimation of subsidence and gas leakage to the surface. The test was carried out for forty hours and production gases were analyzed at every thirty minutes.
Experimental results obtained showed that the combustion propagated along the linking hole inside coal seam. The temperature gradients inside the coal and the composition of production gas were changed under constant oxygen flow rate. But Average thermal value of generated gases by field test was about as much as generated gases by laboratory test.