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Study micromixing pada tangki teraduk secara kontinyu Ali Altway; W Widiyastuti; M Rachimoellah; Sugeng Winardi
Jurnal Teknik Kimia Indonesia Vol 3, No 1 (2004)
Publisher : ASOSIASI PENDIDIKAN TINGGI TEKNIK KIMIA INDONESIA (APTEKIM)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/jtki.2004.3.1.3

Abstract

The aim of this work is to study the influence of micromixing on product distribution for parallel reaction systems in an agitated tank. The understanding of micromixing is needed besides macromixing to obtain the optimum process. The neutralization reaction of NaH2BO3 and oxidation-reduction reaction between lodide-lodate to generate iodine are selected to perform parallel reaction systems. These reactions were conducted in a flat bottom cylindrical tank 0.2 m in diameter (T) at room temperature (30oC) agitated by six blades fan turbine having diameter (Da)=1/3T and impeller width (W)=1/4T. The impeller clearance was I/3H. The height of liquid in the tank is equal to its diameter (H=T). This tank was operated as continuous reactor type. The inf1uences of impeller speed, residence time and feed position were analyzed. Segregation number and the yield of iodine generation determine the micromixing degree and the performance of reactor respectively. The impeller rotation speed was varied 100-300 rpm. The residence time varied 6.01, 4.005 and 3.005 minutes. The feed position was varied on [r"=r/D, z'=z/H] cylindrical coordinate as follows [1.4, 180o, 0.23], [1.4, 180o, 0.33] and [2.4, 180o, 0.92] which represent bulk swept impeller and near surface regions respectively. By increasing the impeller rotation speed and residence time, the iodine yield decrease.The iodine yield is proportional to segregation number. The segregation number Leads to micromixing degree which higher micromixing degree corresponds to the iodine yield decreasing. The impeller swept position gives the smallest the iodine yield compared to others. Keywords: Micromixing, Yield, Segregasion Number.AbstrakPenelitian ini bertujuan untuk mempelajari pengaruh micromixing pada distribusi produk untuk reaksi paralel dalam sistem tangki teraduk. Pemahaman tentang micromixing dalam suatu sistem diperlukan disamping macromixing untuk mendapatkan proses yang optimum. Pada penelitian ini reaksi paralel ini diwakili oleh reaksi netralisasi NaH2BO3 dan reaksi oksidasi-reduksi Iodide-lodate yang menghasilkan lodin. Reaktor beroperasi kontinyu pada suhu kamar (30oC) berupa tangki silinder berdasar datar berdiameter (T)=0.2 m yang diaduk dengan fan turbin enam blade berdiameter (Da)=1/3T dan lebar impeller (W)=1/4T yang dipasang 1/3H dari dasar. Tinggi cairan sama dengan diameter tangki (H=T). Pengaruh kecepatan putar impeller, waktu tinggal dan posisi umpan dianalisa. Bilangan segregasi dihitung untuk menentukan derajat micromixing dan menghitung yield pembentukan iodin untuk menentukan unjuk kerja reaktor. Kecepatan putar impeller divariasi 100-300 rpm. Waktu tinggal divariasikan 6.01, 4.005 and 3.005 menit. Posisi umpan [r'=r/D, z'=z/H] yang merupakan koordinat silinder divariasikan [1.4, 180o, 0.23], [1.4, 180o, 0.33] and [2.4, 180o, 0.92] yang menyatakan masing-masing daerah bulk bawah, sapuan impeller dan dekat permukaan. Semakin tinggi kecepatan putar impeller dan semakin lama waktu tinggal, yield iodin yang dihasilkan semakin keci1. Yield iodin yang dihasilkan sebanding dengan bilangan segregasi. Bilangan segregasi menunjukkan tingkat micromixing dimana semakin besar tingkat micromixing semakin kecil yield iodin yang dihasilkan. Posisi umpan yang memberikan yield iodin yang terkecil adalah pada daerah sapuan impeller. Kata Kunci: Micromixing, Yield, Bilangan Segregasi.
Aplikasi Packet Diffusion Model untuk Menganalisis Pengaruh Fenomena Micromixing terhadap Jalannya Reaksi Kimia Paralel di dalam Reaktor Tangki reraduk Kontinyu dengan Aliran Umpan Terpisah Ali Altway; Sugeng Winardi; M Rachimoellah
Forum Teknik Vol 28, No 2 (2004)
Publisher : Faculty of Engineering, Universitas Gadjah Mada

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Abstract

The effect of turbulent  mixing on  the  course  of two fast parallel competitive  chemical reactions  (netralization  of sodium  biborate  snd  iodide-iodate  oxidation-reduction  reactions) carried  out  in  continuous  stiwed  tank  reaktors  have been  studied  theoretically,  using  PacketDiffusion  Model,  and  experimentally  to  validate  the  theoretical predictions.System studied  consists  of flat bottom  cylindrical  tank  0.2 m in  diameter.  The height of liquid  in  the  tank  is  also  0.2 m. The  tank  was equipped  with Fan Turbine  with diameter equal  to I/3  tank  diameter. Sulphuric  acid solution  (0.5  Il,Q was fed into  the  tank through  2 mm-diameter pipe,  and  the  aquous  solution containing 0.0909  M NaH2Boj,  0.0909  M H:Bo:,  0.0116667  M KI, and  0.0023333  M KIO3wasfed  into  the  tank  through  I0  mm-diameter  pipe.  The rate  of acid solution  was  varied  0,045,  0.068,  and 0.09  liter/minute,  while the  rate  of  the  other solution  was varied  I,  1.5,  and  2 liter/minute  (the  rate  variation  coruespond  to  the  mean residence  time variation of 6, 4, and 3 minutes). The  impeller  rotation  speedwas  varied;  9,12,  and  I5  rps.  The iodine  concenftation  in  the  tank  influent  was  analyzed  using  spectrophotometer.The  simulation  works  conclude  that  the  selectivity  of iodine  decrease  with  increasing impeller  rototion  speed for the  mean  residence  time of 3 and 4 minutes,  while for the  mean residence  time of  6 minutes,  the iodine  selectivity increase  with  increasing  impeller  rotation speed. Increasing  the  mean residence  time from 3 to  4 minutes will decrease  the  iodine selectivity, while  increasing  the  mean residence  time further to  6 minutes  will  increase  the selectivity.  The theoretical  prediction  using  Packet  Difusion  Model agree fairly well  with  the experimental data.  The  experimental studies  also  showed  that  the feed position  in  the  region  of high  turbulent  intensity  (impeller  region)  give  lower iodine  selectivity compaired  to  the selectivity  in  the  region  of lower  turbulent  intensity.  The  Packet  Dffision  Model  cannot simulate  the  effect  offeed  position  on the  iodine  selectivity.Keywords:  Packet  Diffusion Model, Micromixing, and  Continuous  Stirred  Tank  Reactor