Abstract
Construction ventilation system is divided into two stages based on completion status of shafts in the underground petroleum storage project in Jinzhou, China. With the help of theoretical analysis and numerical simulations by using FLUENT software, in the first stage, reasonable construction ventilation is designed and cases with different outside temperature are discussed to investigate the effect of ventilation performance. It is found that with temperature difference increases, peak value of CO concentration, exhausting time of dirty air and required time to meet the CO concentration qualification decrease, but the influence degree is quite limited. Gallery-type network ventilation technique (GNVT) refined from theories of operation ventilation for road tunnel and mining ventilation network, is proposed to conduct the second stage construction ventilation. Ventilation performance of different ventilation schemes with various shafts’ states and diverse arrangements of fans are also analyzed in this study. It turns out that Axial-GNVT with shafts taking in fresh air and access tunnel ejecting dirty air has much better performance than traditional forced ventilation from access tunnel. Improved energy saving scheme is finally adopted to guide the construction. In addition, it is worth mentioning that there is no need to build middle ventilation shafts and construct shafts as large and long as possible. Field test of wind speed, dust, poisonous gas, atmospheric pressure, temperature are performed to detect ventilation effectiveness. Reduction coefficient =0.69is obtained from the test results in consideration of super-large section and it also indicates that there is no difference if the axial fan is at the shaft mouth or in the bottom.
Highlights
At present, water sealed underground petroleum storage caverns in rock, located in coastal regions where granite, welded stuff and other stable lithological rocks are widely distributed, is no doubt a project with better comprehensive economic effect and is the main way used for strategic petroleum reserve [1,2,3,4,5,6,7,8]
I.e., storage caverns have been connected to the ground surface through more than access tunnel, the second-stage construction ventilation, shafts could help air circulation, four main study schemes have been investigated to improve ventilation effectiveness for the second and third steps: a) Effect of different locations, diameters and lengths of shaft on ventilation performance. b) The best network direction of Gallery-type network ventilation technique (GNVT). c) Best fan’s locations around shaft, and nine more cases are studied to discuss the best position in the bottom of shaft. d) Two natural ventilation with shaft schemes simulation
Partial model of scheme 1 is developed to detect ventilation performance in Figure 11(g), as can be seen that one vortex region is produced in the left wall of the shaft, which causes big flow loss and less air flow is introduced into storage cavern, wind speed could come to 4 m/s
Summary
Water sealed underground petroleum storage caverns in rock, located in coastal regions where granite, welded stuff and other stable lithological rocks are widely distributed, is no doubt a project with better comprehensive economic effect and is the main way used for strategic petroleum reserve [1,2,3,4,5,6,7,8]. Cornel et al [18] have focused on multi cross tunnels in one underground coal mine project and performed ventilation network numerical simulation by using Canvent. Li [19] has identified the construction ventilation air safety and health standards combining with the ventilation in the similar engineering construction experience, propane caverns ventilation calculation model was established to determine whether the ventilation program was reasonable based on the theory of three-dimensional numerical simulation and the application of network ventilation via FLUENT software. Stage excavation has been adopted in such underground storage caverns project with large-section and forced ventilation is the preferred alternative method in the first stage. Field air quality tests (wind speed, dust, poisonous gas (methane, CO, SO2, H2S), atmospheric pressure, temperature) with the optimal ventilation scheme developed from above research results are conducted in the constructed tunnels every day to inspect ventilation performance
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