INVESTIGATION OF INCREASING PROCESS GAS COOLING PERFORMANCE BY IMPROVING AMMONIA OXIDATION REACTOR HEAT EXCHANGERS

Abstract

This study aims to increase the cooling performance of NOx gas by improving the heat exchangers of an industrial-type ammonia oxidation reactor with a diameter of 3.8 m and a height of 6.5 m in a nitric acid production plant with a capacity of 610 tons/day. The reactor produces 100% HNO3, 56% diluted nitric acid, and 33 tons/hour of superheated steam. To this end, the parametric analysis study, in which the horizontal and vertical distance between the exchanger tubes, the pipe diameters, and the distance between the exchanger packages (pre-evaporator, superheater, evaporator, economizer) were used separately, was carried out with the help of Ansys Fluent program and the flow properties and performance values were examined. The best cooling performance (for the inner part of the ammonia oxidation reactor) resulted from different parametric studies; there was a study in which the process gas temperature was obtained at 270.510C with a 56 mm horizontal distance between the heat exchanger tubes (a). Thus, a 9.1% decrease in the actual gas outlet temperature of the operating reactor was achieved. In other parametric studies, the lowest process gas temperatures are; it was found to be 323.200C for the distance between heat exchanger packages (L), 318.42 0C for the vertical distance between heat exchanger tubes (b), and 296.67 0C for the heat exchanger tube diameter (D). In addition, when the CFD simulation results, which provide the best cooling performance, are compared with actual operating data (SCADA online data), In the ammonia oxidation reactor, the fluid outlet temperature increased by 8.2% in the economizer, 9.7% in the evaporator and 4.3% in the superheater.

Keywords

• Process Gas Cooling
• Oxidation Reactor
• Heat Exchanger
• CFD Analysis

AMONYAK OKSİDASYON REAKTÖRÜ ISI DEĞİŞTİRİCİLERİNİN İYİLEŞTİRİLMESİYLE PROSES GAZI SOĞUTMA PERFORMANSININ ARTIRILMASININ ARAŞTIRILMASI

Abstract

Bu çalışmada, 610 ton/gün kapasiteli bir nitrik asit üretim tesisindeki 3,8 m çapında ve 6,5 m yüksekliğindeki endüstriyel tip amonyak oksidasyon reaktörünün ısı değiştiricilerini iyileştirerek, NOx gazının soğutma performansının artırılması amaçlanmıştır. Reaktör, % 100 HNO3, %56 seyreltilmiş nitrik asit ve 33 ton/saat aşırı ısıtılmış buhar üretmektedir. Bu amaçla, eşanjör boruları arasındaki yatay ve düşey mesafe, boru çapları ve eşanjör paketleri (ön buharlaştırıcı, aşırı ısıtıcı, buharlaştırıcı, ekonomizer) arasındaki mesafenin ayrı ayrı kullanıldığı parametrik analiz çalışması, Ansys Fluent programı yardımıyla yapılmış ve akış özellikleri ile performans değerleri incelenmiştir. En iyi soğutma performansı farklı parametrik çalışmalar sonucunda; ısı değiştirici boruları arasında yatay olarak 56 mm mesafede proses gazı sıcaklığının 270,5 0C elde edildiği çalışma ile sağlanmıştır. Böylece, reaktörün gaz çıkış sıcaklığında % 9,1'lik bir azalma sağlanmıştır. Diğer parametrik çalışmalarda ise en düşük proses gazı sıcaklıkları; ısı değiştirici paketleri arasındaki mesafe (L) için 323,2 0C, ısı değiştirici boruları arasındaki dikey mesafe (b) için 318,4 0C ve ısı değiştirici boru çapı (D) için 296,6 0C olarak bulunmuştur. Ayrıca, en iyi soğutma performansını sağlayan CFD simülasyon sonuçları, gerçek işletme verileriyle (SCADA verileri ile) karşılaştırıldığında; amonyak oksidasyon reaktöründe soğutucu akışkan çıkış sıcaklığı ekonomizerde %8,2, buharlaştırıcıda %9,7 ve süperheater'da %4,3 artmıştır.

Keywords

• Proses Gaz Soğutma
• Oksidasyon Reaktörü
• Isı Eşanjörü
• CFD Analizi

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