In order to suppress the harm of gas explosion,the current study researched on the body of vacuum chamber.The previous studies verifed that it could obviously lower the explosion overpressure by reasonably arranging v...In order to suppress the harm of gas explosion,the current study researched on the body of vacuum chamber.The previous studies verifed that it could obviously lower the explosion overpressure by reasonably arranging vacuum chamber on pipe.That is to say,the vacuum chamber has the effect of absorbing wave and energy.To further deeply analyze the vacuum chamber suppressing gas explosion,this research designed the L-type pipe of gas explosion,and compared the experimental results of gas explosion with vacuum chamber and without vacuum chamber.Besides,using the gas chromatograph,this study also investigated the gas compositions in the pipe before and after explosion.The results show that:(1)without vacuum chamber,the maximum value of explosion overpressure is 0.22 MPa,with60 ms duration,and after explosion,the concentration of oxygen drops to 12.07%,but the concentration of carbon monoxide increases to 4392.3 10à6,and the concentration of carbon dioxide goes up to7.848%,which can make the persons in danger suffocate and die;(2)with vacuum chamber,explosion overpressure drops to 0.18 MPa,with 20 ms duration or less,and after explosion,the concentration of oxygen still remains 12.07%,but the concentration of methane is 7.83%,however the concentration of carbon monoxide is only 727.24 10à6,and the concentration of carbon dioxide is only 1.219%,at the this moment the concentration ratio of toxic gas drops by more than 83%in comparison to be that without vacuum chamber.Consequently,the vacuum chamber can guarantee that most methane does not take part in chemical reaction,and timely quenches the deflagration reaction of gas and oxygen.Because of the two points mentioned above,it reduces the explosion energy,and lowers that the overpressure of blast wave impacts and damages on the persons and facilities,and also decreases the consumption of oxygen and the production of the toxic gas.Therefore,it is safe to conclude that the vacuum chamber not only absorbs wave and energy,but also prevents and suppresses explosion.展开更多
In this paper, a miniaturized bionic electronic nose system is developed in order to solve the problems arising in oil and gas detection for large size and inflexible operation in downhole. The bionic electronic nose ...In this paper, a miniaturized bionic electronic nose system is developed in order to solve the problems arising in oil and gas detection for large size and inflexible operation in downhole. The bionic electronic nose chamber is designed by mimicking human nasal turbinate structure, V-groove structure on shark skin surface and flow field distribution around skin surface. The sensitivity of the bionic electronic nose system is investigated through experimentation. Radial Basis Function （RBF） and Support Vector Machines （SVM） of 10-fold cross validation are used to compare the recognition performance of the bionic electronic nose system and common one. The results show that the sensitivity of the bionic electronic nose system with bionic composite chamber （chamber B） is significantly improved compared with that with common chamber （chamber A）. The recognition rate of chamber B is 4.27% higher than that of chamber A for the RBF algorithm, while for the SVM algorithm, the recognition rate of chamber B is 5.69% higher than that of chamber A. The three-dimensional simulation model of the chamber is built and verified by Computational Fluid Dynamics （CFD） simulation analysis. The number of vortices in chamber B is fewer than that in chamber A. The airflow velocity near the sensors inside chamber B is slower than that inside chamber A. The vortex intensity near the sensors in chamber B is 2.27 times as much as that in chamber A, which facilitates gas molecules to fully contact with the sensor surface and increases the intensity of sensor signal, and the contact strength and time between odorant molecules and sensor surface. Based on the theoretical investigation and test validation, it is believed that the proposed bionic electronic nose system with bionic composite chamber has potential for oil and gas detection in downhole.展开更多
基金Financial support from the State Key Laboratory Cultivation Base for Gas Geology and Gas Control of Henan Polytechnic University of China(No.WS2012A04)
文摘In order to suppress the harm of gas explosion,the current study researched on the body of vacuum chamber.The previous studies verifed that it could obviously lower the explosion overpressure by reasonably arranging vacuum chamber on pipe.That is to say,the vacuum chamber has the effect of absorbing wave and energy.To further deeply analyze the vacuum chamber suppressing gas explosion,this research designed the L-type pipe of gas explosion,and compared the experimental results of gas explosion with vacuum chamber and without vacuum chamber.Besides,using the gas chromatograph,this study also investigated the gas compositions in the pipe before and after explosion.The results show that:(1)without vacuum chamber,the maximum value of explosion overpressure is 0.22 MPa,with60 ms duration,and after explosion,the concentration of oxygen drops to 12.07%,but the concentration of carbon monoxide increases to 4392.3 10à6,and the concentration of carbon dioxide goes up to7.848%,which can make the persons in danger suffocate and die;(2)with vacuum chamber,explosion overpressure drops to 0.18 MPa,with 20 ms duration or less,and after explosion,the concentration of oxygen still remains 12.07%,but the concentration of methane is 7.83%,however the concentration of carbon monoxide is only 727.24 10à6,and the concentration of carbon dioxide is only 1.219%,at the this moment the concentration ratio of toxic gas drops by more than 83%in comparison to be that without vacuum chamber.Consequently,the vacuum chamber can guarantee that most methane does not take part in chemical reaction,and timely quenches the deflagration reaction of gas and oxygen.Because of the two points mentioned above,it reduces the explosion energy,and lowers that the overpressure of blast wave impacts and damages on the persons and facilities,and also decreases the consumption of oxygen and the production of the toxic gas.Therefore,it is safe to conclude that the vacuum chamber not only absorbs wave and energy,but also prevents and suppresses explosion.
基金This work was supported by the Key Scientific and Technological Research and Development Projects in Jilin Province （Grant No. 20180201038GX）, Jilin Province Development and Reform Commission （Grant Nos. 2016C029 and 2017C051-3）, the Education Department of Jilin Province （Grant Nos. [2015] 490, JJKH20170791K J, JJKH20170812KJ and 20150520075 JH） and the China Postdoctoral Science Foundation （Grant No. 2016M601383）.
文摘In this paper, a miniaturized bionic electronic nose system is developed in order to solve the problems arising in oil and gas detection for large size and inflexible operation in downhole. The bionic electronic nose chamber is designed by mimicking human nasal turbinate structure, V-groove structure on shark skin surface and flow field distribution around skin surface. The sensitivity of the bionic electronic nose system is investigated through experimentation. Radial Basis Function （RBF） and Support Vector Machines （SVM） of 10-fold cross validation are used to compare the recognition performance of the bionic electronic nose system and common one. The results show that the sensitivity of the bionic electronic nose system with bionic composite chamber （chamber B） is significantly improved compared with that with common chamber （chamber A）. The recognition rate of chamber B is 4.27% higher than that of chamber A for the RBF algorithm, while for the SVM algorithm, the recognition rate of chamber B is 5.69% higher than that of chamber A. The three-dimensional simulation model of the chamber is built and verified by Computational Fluid Dynamics （CFD） simulation analysis. The number of vortices in chamber B is fewer than that in chamber A. The airflow velocity near the sensors inside chamber B is slower than that inside chamber A. The vortex intensity near the sensors in chamber B is 2.27 times as much as that in chamber A, which facilitates gas molecules to fully contact with the sensor surface and increases the intensity of sensor signal, and the contact strength and time between odorant molecules and sensor surface. Based on the theoretical investigation and test validation, it is believed that the proposed bionic electronic nose system with bionic composite chamber has potential for oil and gas detection in downhole.
