摘要:
煤制氢是煤炭能源低碳转型的有效方案,针对煤制氢通入天然气管网大规模输送过程中安全问题,研究了非预混二氧化碳(Carbon dioxide,CO2)喷射下掺氢天然气爆炸特性的影响。自主设计并搭建了爆炸实验平台,系统探究非预混CO2的喷射压力(0 ~ 1.00 MPa)和喷射时间(0 ~ 180 ms,喷射早于点火开启的时间)对爆炸火焰传播行为和压力特性的影响规律。结果表明:非预混CO2喷射显著影响甲烷/氢气/空气预混气爆炸行为。CO2喷射会引起湍流效应导致火焰褶皱和结构改变,从而增加火焰传播速度和爆炸压力。当喷射时间固定时(如0或120 ms),增加喷射压力会引入更多的CO2,增强局部湍流和扰动,加剧火焰加速和爆炸后果。随着喷射时间增加,不同喷射压力下最大爆炸压力均呈先增后减的趋势。CO2喷射对爆炸的湍流促进作用和稀释作用相互竞争,并存在临界喷射时间。过多的CO2喷射时会增强它的稀释作用,削弱CO2喷射对爆炸的湍流扰动能力,降低爆炸强度。此外,较大的喷射压力有着更小的临界喷射时间,同时较大喷射压力下的最大爆炸压力对喷射时间的变化有着更高的敏感性。喷射压力和时间是CO2喷射影响掺氢天然气爆炸危险的关键参数,为天然气管网氢能输送安全防控策略提供重要理论依据。
Abstract:
Coal-to-hydrogen is an effective solution for the low-carbon transformation of coal energy. To address the explosion safety issues during coal-to-hydrogen transportation via the natural gas pipeline network, the effect of non-premixed CO2 injection on the explosion characteristics of hydrogen-doped natural gas was investigated. An experimental explosion platform was independently designed and constructed to actively release CO2 into the hydrogen-doped methane explosion via a high-pressure gas injection device. The CO2 injection was turned on earlier than ignition to create a non-premixed turbulent atmosphere. The volume of CO2 injection was controlled by injection pressure (0, 0.5, 0.75, and 1.00 MPa) and injection time (0, 60, 120, and 180 ms). The explosion flame propagation dynamics and pressure behavior under non-premixed CO2 injection were analyzed. Results showed that injection pressure and injection time significantly influence the premixed explosion process. The injection of non-premixed CO2 into the premixed explosion induces turbulence, causing flame wrinkling. Structural changes in wrinkled flames increase the flame surface area, leading to accelerated flame propagation and enhanced explosion intensity. For a given injected time (e.g., 0 or 120 ms), increasing the injection pressure introduces more CO2, which enhances localized turbulence and disturbance in the flame, leading to further flame acceleration and more severe explosion consequences. As the injection time increases, the maximum explosion pressure of different injection pressures increases and then decreases. CO2 injection in the explosion plays a competitive relationship between turbulence promotion and dilution effect, and there is a critical injection time. Excessive CO2 injection can enhance its dilution effect, weakening the CO2 injection on the explosion of turbulence perturbation ability, which reduces the explosion intensity. Moreover, a larger injection pressure has a smaller critical injection time. Meanwhile, the maximum explosion pressure at larger injection pressures has a higher sensitivity to changes in injection time. Injection pressure and injection time are the key parameters of CO2 injection affecting the explosion hazard of hydrogen-doped natural gas. The findings provide fundamental guidelines for the safety prevention and control strategy of hydrogen transportation in the natural gas pipeline network.