About Teknik Kimia

Tanpa sadar, setiap saat kita berhubungan dengan Proses Teknik Kimia. Uncontiously, we are dealing with Chemical Engineering Process everytime. Teknik Kimia menekankan pembelajaran merekayasa proses untuk memproduksi secara massal bahan-bahan kimia. Sebuah contoh menarik di ceritakan berikut ini:

One interesting example is told below:

Proses pelarutan garam (Salt dissolving process)

Bayangkan sebuah tangki berdiameter 1,5 m yang didalamnya telah diisikan larutan garam sedalam 0,75 m, lalu bayangkan bila diatasnya diletakkan air murni setebal 0,75 m, dengan sangat hati-hati tanpa mengganggu air garam dibawahnya. Bila isi tangki tersebut dibiarkan tanpa gangguan, air garam akan ber difusi di tahap molekuler, dan berpermeasi ke dalam air murni, yang konsentrasi akhirnya akan menjadi setengah dari kadar garam awal.

Tetapi proses ini sangat lambat, dan dapat dihitung bahwa konsentrasi garam pada permukaan akan hanya 87,5% dari konsentrasi seharusnya setelah ditunggu 10 tahun; dan akan mencapai 99% dari konsentrasi yang seharusnya setelah 28 tahun.

Pada sisi lain, telah dibuktikan bahwa dengan pengaduk sederhana yang berputar mengaduk isi tangki pada kecepatan 22 rpm akan membuat pencampuran sempurna lebih kurang dalam waktu 60 detik.

(Wood,J.C., 1922, in Trayball, R.E., Mass Transfer Operations, 3rd Ed., Mc.Graw Hill.)

How about pouring our coffee in the morning?

Bagaimana dengan penyeduhan kopi di pagi hari? Saat menyeduh kopi dipagi hari, cobalah untuk menggunakan gelas yang tembus pandang; letakkan gula dan kopi dalam lapisan, lalu tuangkan air panas dan biarkan seduhan anda tersebut, tanpa mengaduknya. Hingga matahari terbenam, kumpulan gula di dasar gelas masih akan tetap ada, dan kopi masih juga pahit.

When starting the day with morning coffee, try using a transparent glass; pour the sugar and coffee, then pour the boiling water and leave it, with out mixing.
By the sun-sets, the sugar in the bottom of the glass is still clearly visible, and the coffee is yet, bitter.

Topik seperti inilah yang dipelajari dalam Teknik Kimia.

About Granulator

Drying / Cooling

These are the most frequent applications of large fluid bed systems. Different process systems are applied depending upon product, volatiles, operational safety and environmental requirements.

Open system

Featuring atmospheric air in a once-through system where water is to be removed. Normally a push-pull system is used to balance the pressure to be slightly negative in the free board of the fluid bed. Depending upon the product and available heat source, direct or indirect heating may be applied. The exhaust air is cleaned by e.g. bag filter, cyclone with or without wet scrubber.

In cases where products pose a dust explosion risk, open cycle systems feature pressure shock resistant components or alternatively semi-closed cycle, self-inertizing layouts can be considered.

Closed cycle system

Featuring drying in an inert gas atmosphere (usually nitrogen) recycling within the system. It must be used for drying feedstocks containing organic volatiles or where the product must not contact oxygen during drying.Closed cycle systems are gastight, and addition of inert gas is controlled by monitoring the oxygen content of the drying gas and the system pressure, which is kept positive. The evaporated volatiles are recovered in a condenser.

Agglomeration / Granulation

Fluid bed processing requires that the solids are in particulate form prior to entering the fluid bed. In the special case of fluid bed spray granulation, particles are built up in the fluid bed by spraying a liquid into the fluidized layer particles. Particulate solids ideal for fluid bed processing may be formed in an independent process step such as crystallization, coagulation, or polymerization, followed by mechanical dewatering. Particles may also be formed by spray drying. In other cases dry or wet solid particles may have to undergo a degree of agglomeration or granulation prior to entering the fluid bed.

Rewet agglomeration system

In the rewet agglomeration system, a fine powder is conveyed to an agglomeration chamber where the powder is dispersed in air and contacted with a spray of liquid. Moist, porous agglomerates are formed and subsequently dried under lenient fluidization conditions in a Vibro-Fluidizer®. After cooling, the powder is discharged, classified, and fines recycled for further agglomeration together with fines from the exhaust air dust collector. Rewet agglomeration systems are typically used for food products like coffee, cocoa-sugar, where instant properties and coarse particles are required.

Survey of agglomeration and granulation processes using fluid bed technology
Feed material	Particle formation	Drying
Fine, dry powder Dry powder	Rewet agglomeration Tumbling layer	Fluid Bed Drying
Friable wet cake Plastic wet cake Pasty wet cake	Milling Extrusion Back-mixing and tumbling layer or extrusion
Liquid	Fluid bed spray granulation

Batch Fluid Bed Systems

Batch fluid bed processing allows several process steps (mixing, agglomerating, drying and cooling) to be carried out in a single unit. The batch process assures uniformity of all product within a batch and allows every unit of final product to be traced to a given batch run.

Batch

Niro supply a full range of customized batch fluid bed systems for food ingredients, chemical and pharmaceutical applications. Systems are available in various sizes, from laboratory and pilot-scale to large production units. Our batch fluid bed technology is developed by our sister-company Aeromatic-Fielder (located in Switzerland and UK) and it:

• enables control bulk density

• improves dispersibility

• reduces dust

• provides timed release of active ingredients

• enables tablet compression

Processors known as:

• Agglomeration

• Coating

• Drying

• Granulation

All fluid bed systems can be pre-assembled in modules or skids to provide rapid on-site start-up.