Pyrolysis was carried out in an entrained flow drop-tube furnace(DTF)and tube furnace(TF)using Pingzhuang lignite coal with various catalyst concentrations(2 wt%,4 wt%,and 6 wt%)of KCl and CaCl2 for the syngas compone...Pyrolysis was carried out in an entrained flow drop-tube furnace(DTF)and tube furnace(TF)using Pingzhuang lignite coal with various catalyst concentrations(2 wt%,4 wt%,and 6 wt%)of KCl and CaCl2 for the syngas component at 800°C-1200°C.Five catalysts(KCl,CaCl2,NiCl2,MnCl2,and ZnCl2)at 6 wt%were chosen for DTF at 800°C-1200°C.An online gas chromatograph analyzer and the Fourier transform infrared spectra were used for the analysis of the syngas and char structure.Results showed that the overall CO2 and CH4 content in DTF was lower than that in TF,mainly due to the CH4 carbon reaction at high temperature.Moreover,the CO%in DTF was higher than in the TF experiment,as char reacts with carbon dioxide to form carbon monoxide.In DTF experiment,the maximum and minimum CO2 content was 15.20%with 6 wt%Mn at 800℃ and 0.33%with 6 wt%K at 1100℃,respectively.The maximum CO%was found in raw coal.Concentrations of Mn^2+,Zn^2+,and K can significantly increase H2%,whereas Ca^2+ and Ni^2+have a minor effect on H2%;however,the overall presence of catalyst has a positive impact on the H2 content.展开更多
Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Uni...Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Union achieved commercialised production.In this century,a few pilot projects in Australia also achieved short-term small-scale commercialised production using modern UCG technology.However,the commercialisation of UCG,especially medium-deep UCG projects with good development prospects but difficult underground engineering conditions,has not progressed smoothly around the world.Considering investment economy,a single gasifier must realise a high daily output and accumulated output,as well as hold a long gasification tunnel to control a large number of coal resources.However,a long gasification tunnel can easily be affected by blockages and failure,for which the remedial solutions are difficult and expensive,which greatly restricts the investment economy.The design of the underground gasifier determines the success or failure of UCG projects,and it also requires the related petroleum engineering technology.Combining the advantages of the linear horizontal well(L-CRIP)and parallel horizontal well(P-CRIP),this paper proposes a new design scheme for an“inclined ladder”underground gasifier.That is to say,the combination of the main shaft of paired P-CRIP and multiple branch horizontal well gasification tunnels is adopted to realise the control of a large number of coal resources in a single gasifier.The completion of the main shaft by well cementation is beneficial for maintaining the integrity of the main shaft and the stability of the main structure.The branch horizontal well is used as the gasification tunnel,but the length and number of retracting injection points are limited,effectively reducing the probability of blockage or failure.The branch horizontal well spacing can be adjusted flexibly to avoid minor faults and large cracks,which is conducive to increasing the resource utilisation rate.In addition,for multi-layer thin coal seams or ultra-thick coal seams,a multi-layer gasifier sharing vertical well sections can be deployed,thereby saving investment on the vertical well sections.Through preliminary analysis,this gasifier design scheme can be realised in engineering,making it suitable for largescale deployment where it can increase the resource utilisation rate and ensure stable and controllable operations.The new gasifier has outstanding advantages in investment economy,and good prospects for application in the commercial UCG projects of medium-deep coal seams.展开更多
基金supported by the Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51621005)
文摘Pyrolysis was carried out in an entrained flow drop-tube furnace(DTF)and tube furnace(TF)using Pingzhuang lignite coal with various catalyst concentrations(2 wt%,4 wt%,and 6 wt%)of KCl and CaCl2 for the syngas component at 800°C-1200°C.Five catalysts(KCl,CaCl2,NiCl2,MnCl2,and ZnCl2)at 6 wt%were chosen for DTF at 800°C-1200°C.An online gas chromatograph analyzer and the Fourier transform infrared spectra were used for the analysis of the syngas and char structure.Results showed that the overall CO2 and CH4 content in DTF was lower than that in TF,mainly due to the CH4 carbon reaction at high temperature.Moreover,the CO%in DTF was higher than in the TF experiment,as char reacts with carbon dioxide to form carbon monoxide.In DTF experiment,the maximum and minimum CO2 content was 15.20%with 6 wt%Mn at 800℃ and 0.33%with 6 wt%K at 1100℃,respectively.The maximum CO%was found in raw coal.Concentrations of Mn^2+,Zn^2+,and K can significantly increase H2%,whereas Ca^2+ and Ni^2+have a minor effect on H2%;however,the overall presence of catalyst has a positive impact on the H2 content.
文摘Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Union achieved commercialised production.In this century,a few pilot projects in Australia also achieved short-term small-scale commercialised production using modern UCG technology.However,the commercialisation of UCG,especially medium-deep UCG projects with good development prospects but difficult underground engineering conditions,has not progressed smoothly around the world.Considering investment economy,a single gasifier must realise a high daily output and accumulated output,as well as hold a long gasification tunnel to control a large number of coal resources.However,a long gasification tunnel can easily be affected by blockages and failure,for which the remedial solutions are difficult and expensive,which greatly restricts the investment economy.The design of the underground gasifier determines the success or failure of UCG projects,and it also requires the related petroleum engineering technology.Combining the advantages of the linear horizontal well(L-CRIP)and parallel horizontal well(P-CRIP),this paper proposes a new design scheme for an“inclined ladder”underground gasifier.That is to say,the combination of the main shaft of paired P-CRIP and multiple branch horizontal well gasification tunnels is adopted to realise the control of a large number of coal resources in a single gasifier.The completion of the main shaft by well cementation is beneficial for maintaining the integrity of the main shaft and the stability of the main structure.The branch horizontal well is used as the gasification tunnel,but the length and number of retracting injection points are limited,effectively reducing the probability of blockage or failure.The branch horizontal well spacing can be adjusted flexibly to avoid minor faults and large cracks,which is conducive to increasing the resource utilisation rate.In addition,for multi-layer thin coal seams or ultra-thick coal seams,a multi-layer gasifier sharing vertical well sections can be deployed,thereby saving investment on the vertical well sections.Through preliminary analysis,this gasifier design scheme can be realised in engineering,making it suitable for largescale deployment where it can increase the resource utilisation rate and ensure stable and controllable operations.The new gasifier has outstanding advantages in investment economy,and good prospects for application in the commercial UCG projects of medium-deep coal seams.
