A control strategy of flow reversal with hot gas withdrawal for heat recovery and its application in mitigation and utilization of ventilation air methane in a reverse flow reactor

2013 ◽  
Vol 228 ◽  
pp. 243-255 ◽  
Author(s):  
Zhikai Li ◽  
Zhangfeng Qin ◽  
Yagang Zhang ◽  
Zhiwei Wu ◽  
Hui Wang ◽  
...  
Author(s):  
Krzysztof Gosiewski ◽  
Anna Pawlaczyk-Kurek

Abstract The problem discussed in the paper was revealed during experimental and simulation study of the waste fuel utilization (low concentrated CH4) which in coal mines is emitted to the atmosphere as the so-called ventilation air methane (abbreviation: VAM). When an intense heat recovery would be applied to the Reverse-Flow Reactor (RFR) then the reactor becomes susceptible to creation of temperature profiles asymmetry. This may adversely affects the heat recovery efficiency. When a strong asymmetry arises, it can significantly reduce the heat recovery and the system needs immediate counteraction. Commonly used control systems do not always cope with this problem. The paper discusses various RFRs control algorithms from the point of view of the ability to reduce symmetry to the acceptable range. The impact of the loss of reactor symmetry on possible heat recovery efficiency is also briefly discussed. The work is focused on RFRs which operate with significant heat recovery in a heat exchange unit in which heat is retrieved not at the rector outlet, but by cooling the hot gas from the center part of the reactor. Issues discussed in the paper are derived from being carried out in ICE-PAS through many years of simulation research, patent examinations, but primarily from the own experiences on the research & demonstration thermal flow reversal reactor (TFRR) for VAM combustion. Computer control & data recording system process data records of the experiments enabled effectively analyze the problem of creating and preventing thermal asymmetry.


2018 ◽  
Vol 5 (3) ◽  
pp. 490
Author(s):  
Yogi W Budhi

In principle, reactor perturbation by flow reversal can be used for manipulation of catalyst surface coverage if a dedicated and proper operation procedure can be developed. A mathematical model and analysis of reverse flow reactor behaviour for the ammonia oxidation over platinum have been performed. Series of reverse flow experiments were carried out on a laboratory reactor scale. The influence of flow reversals on the conversion and selectivity at various switching times was observed and evaluated. Other process variables such as gas residence time, reaction temperature, and oxygen concentration in the feed were points of interest. Assessment of reactor dynamics in the kinetic regimes can be achieved most expediently by implementing a comparable switching time and gas residence time. Model and experimental results indicate that regular reverse flow operation for manipulation of catalyst surface coverage always induces a decrease of conversion. It was also found that the selectivity due to flow reversal was rather insensitive to changes in the switching frequency.Keywords: Ammonia oxidation, Kinetic regime, Reactor modeling, Residence time distribution, Reverse flow reactor operation, Transient operation AbstrakPada dasarnya pertubasi reaktor oleh aliran balik dapat digunakan untuk mengatasi penutupan permukaan katalis manakala suatu suatu prosedur operasi yang spesifik dan sesuai bisa dibangun. Analisa dan model matematika kelakuan reaktor batik untuk oksidasi amoniak pada pelat platina telah dilakukan. Serangkaian percobaan aliran balik telah dilangsungkan dalam skala laboratorium. Pengaruh aliran batik terhadap konversi dan selektivitas pada berbagaijumlah putaran aliran telah diamati dan dievaluasi. Variabel proses lainnya, seperti waktu tinggal gas, temperature reaksi, dan konsentrasi oksigen pada umpan telah menjadi perhatian pada penelitian ini. Perkiraan dinamika reaktor dalam rejim kinetika umumnya dapat diperoleh melalui penelusuran implementasi jumlah putaran aliran dan waktu tinggal gas dengan perbandingan tertentu. Hasil percobaan dan pemodelan mengindikasikan bahwa operasi aliran batik reguler untuk memanipulasi penutupan permukaan katalis selalu mengakibatkan penurunan konversi. Selain itu, ditemukan juga bahwa selectivitas terhadap pembalikan aliran kurang sensitif terhadap perubahan pada frekuensi putaran aliran.Keywords: Distribusi waktu tinggal, Operasi reaktor aliran batik, Operasi transient, Oksidasi amoniak, Pemodelan reaktor, Rejim kinetika


AIChE Journal ◽  
2007 ◽  
Vol 53 (8) ◽  
pp. 2084-2096 ◽  
Author(s):  
Erasmo Mancusi ◽  
Lucia Russo ◽  
Antonio Brasiello ◽  
Silvestro Crescitelli ◽  
Mario di Bernardo

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