超临界二氧化碳管道输送安全是碳捕集与封存技术(Carbon Capture and Storage,即CCS)的一个重要环节。当超临界管道压力过高时,一般采用节流方式泄放管内高压,节流过程产生的温降可以根据绝热假设进行预测。根据绝热假设及能量守恒关系...超临界二氧化碳管道输送安全是碳捕集与封存技术(Carbon Capture and Storage,即CCS)的一个重要环节。当超临界管道压力过高时,一般采用节流方式泄放管内高压,节流过程产生的温降可以根据绝热假设进行预测。根据绝热假设及能量守恒关系,通过求解临界节流过程中出口速度与音速的关系式,建立临界节流比与绝热指数关系;烟气二氧化碳中含有杂质,会影响节流过程中产生的温降,根据伯努利方程及等温焓差迭代方法计算节流温降,并依据二元交互作用系数混合规则分析超临界二氧化碳管道中杂质对节流温降的影响。研究结果表明:当二氧化碳中含有的杂质为二氧化硫时,有助于提高节流后的温度,并降低发生干冰堵塞的可能,然而当杂质为氮气时则会进一步降低节流后的温度。通过实例分析给出烟气二氧化碳节流具体操作建议:当采用多级节流时,较高的初始温度可以防止放空管出口处形成干冰。展开更多
临汾致密气井采用排水采气工艺,井口高压节流易发生冰堵风险,目前采用真空加热炉加热后节流的解决方案。但是,致密气井压力衰减速度快,导致真空加热炉使用周期短、利用率低,且体积和质量大,设备搬迁困难。为此研究电磁加热、催化式红外...临汾致密气井采用排水采气工艺,井口高压节流易发生冰堵风险,目前采用真空加热炉加热后节流的解决方案。但是,致密气井压力衰减速度快,导致真空加热炉使用周期短、利用率低,且体积和质量大,设备搬迁困难。为此研究电磁加热、催化式红外加热、涡流管加热、石墨烯加热等新技术在致密气井的适用性,首先对比分析了各项加热技术的优缺点,建立了以加热功率和温度为边界的选型图版。其次,提出了含水致密气加热功率计算方法,并建立了加热技术选型流程。最后结合现场生产工况,热毯式电磁加热技术覆盖5~160 k W、0~95℃的工况范围,能够满足现场加热需求,且设备体积和质量小、拆装便捷、加热效率高,可减小设备投资、提高设备利用率。建立的加热技术边界图版和选型方法流程,可为致密气井加热技术选型提供支撑,从而实现降本增效、节能减排的目标。展开更多
For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow ...For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow loss in a compressor stator passage during the throttling process. The flow loss was divided accurately and quantitatively, based on the evolutionary process of the vortex structures. According to the position of the singular points of the vortex structures, the influence of the evolution of the vortex structures on the generation and development of the flow loss was analyzed on a microscale scale. Thereafter, this paper provided the vortex dynamic mechanism of the flow loss, which was important to enrich the theoretical system of the flow field in the compressor. The results show that: the flow loss at the top of the stator tip is caused by the low-energy fluid clusters, which are transported and accumulated by the vortices from the endwall; the transport effect of the pressure separation vortex at the upper half-height only migrates the position of the flow losses, but there is new flow loss generated by its shear action to the endwall. The dominant flow loss during the throttling process concentrates upon the closed separation bubble around the middle of the suction side of the stator.展开更多
节流过程是热力学的基本过程之一,它描述了实际气体在绝热等焓过程中的温度变化,其变化趋势由反转曲线方程决定。本文首先回顾了反转曲线方程的一般计算方法,并利用实际气体的Onnes状态方程,推导了它的严格形式。进而,利用两种常用的状...节流过程是热力学的基本过程之一,它描述了实际气体在绝热等焓过程中的温度变化,其变化趋势由反转曲线方程决定。本文首先回顾了反转曲线方程的一般计算方法,并利用实际气体的Onnes状态方程,推导了它的严格形式。进而,利用两种常用的状态方程(van der Waals方程与Dieterici方程),得到了反转曲线方程的近似的具体形式。进而,以氮气为例,将理论结果与实验数据进行了系统的比较,发现由这两种状态方程得到的反转曲线分别在低温区及高温区与实验数据相符。最后,分别对两者产生偏差的区域进行了分析。展开更多
文摘超临界二氧化碳管道输送安全是碳捕集与封存技术(Carbon Capture and Storage,即CCS)的一个重要环节。当超临界管道压力过高时,一般采用节流方式泄放管内高压,节流过程产生的温降可以根据绝热假设进行预测。根据绝热假设及能量守恒关系,通过求解临界节流过程中出口速度与音速的关系式,建立临界节流比与绝热指数关系;烟气二氧化碳中含有杂质,会影响节流过程中产生的温降,根据伯努利方程及等温焓差迭代方法计算节流温降,并依据二元交互作用系数混合规则分析超临界二氧化碳管道中杂质对节流温降的影响。研究结果表明:当二氧化碳中含有的杂质为二氧化硫时,有助于提高节流后的温度,并降低发生干冰堵塞的可能,然而当杂质为氮气时则会进一步降低节流后的温度。通过实例分析给出烟气二氧化碳节流具体操作建议:当采用多级节流时,较高的初始温度可以防止放空管出口处形成干冰。
文摘临汾致密气井采用排水采气工艺,井口高压节流易发生冰堵风险,目前采用真空加热炉加热后节流的解决方案。但是,致密气井压力衰减速度快,导致真空加热炉使用周期短、利用率低,且体积和质量大,设备搬迁困难。为此研究电磁加热、催化式红外加热、涡流管加热、石墨烯加热等新技术在致密气井的适用性,首先对比分析了各项加热技术的优缺点,建立了以加热功率和温度为边界的选型图版。其次,提出了含水致密气加热功率计算方法,并建立了加热技术选型流程。最后结合现场生产工况,热毯式电磁加热技术覆盖5~160 k W、0~95℃的工况范围,能够满足现场加热需求,且设备体积和质量小、拆装便捷、加热效率高,可减小设备投资、提高设备利用率。建立的加热技术边界图版和选型方法流程,可为致密气井加热技术选型提供支撑,从而实现降本增效、节能减排的目标。
基金supported by a project funded by the China Postdoctoral Science Foundation(Grant No.2017M621268)the National Natural Science Foundation of China(Grant Nos.51436002,51506020,and 51706051)
文摘For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow loss in a compressor stator passage during the throttling process. The flow loss was divided accurately and quantitatively, based on the evolutionary process of the vortex structures. According to the position of the singular points of the vortex structures, the influence of the evolution of the vortex structures on the generation and development of the flow loss was analyzed on a microscale scale. Thereafter, this paper provided the vortex dynamic mechanism of the flow loss, which was important to enrich the theoretical system of the flow field in the compressor. The results show that: the flow loss at the top of the stator tip is caused by the low-energy fluid clusters, which are transported and accumulated by the vortices from the endwall; the transport effect of the pressure separation vortex at the upper half-height only migrates the position of the flow losses, but there is new flow loss generated by its shear action to the endwall. The dominant flow loss during the throttling process concentrates upon the closed separation bubble around the middle of the suction side of the stator.
文摘节流过程是热力学的基本过程之一,它描述了实际气体在绝热等焓过程中的温度变化,其变化趋势由反转曲线方程决定。本文首先回顾了反转曲线方程的一般计算方法,并利用实际气体的Onnes状态方程,推导了它的严格形式。进而,利用两种常用的状态方程(van der Waals方程与Dieterici方程),得到了反转曲线方程的近似的具体形式。进而,以氮气为例,将理论结果与实验数据进行了系统的比较,发现由这两种状态方程得到的反转曲线分别在低温区及高温区与实验数据相符。最后,分别对两者产生偏差的区域进行了分析。
