Bài giảng Kỹ thuật phản ứng sinh học: Chương 6 - Bùi Hồng Quân

Bài giảng Kỹ thuật phản ứng sinh học: Chương 6 Nâng cấp các phản ứng sinh học, cung cấp cho người học những kiến thức như: Khái niệm cơ bản; Nguyên tắc nâng cấp phản ứng sinh học; Kỹ thuật nâng cấp phản ứng sinh học. Mời các bạn cùng tham khảo!
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Bài giảng Kỹ thuật phản ứng sinh học: Chương 6 - Bùi Hồng Quân http://buihongquan.comChương 6. Nâng cấp các phản ứng sinh học  6.1. Khá i niệ m cơ bả n  6.2. Nguyên tá c nang cá p phả n ứng sinh họ c  6.3. Kỹ thuạ t nang cá p phả n ứng sinh họ c12/23/2018 Bioreaction engineering. 257 http://buihongquan.com The stirred tank bioreactor (STR) A typical bioreactor used for microbial fermentations is shown in the following figure:Laboratory scale bioreactors with liquid volumes of less than 10 litres areconstructed 12/23/2018 out of Pyrex glass. For larger reactors, stainless steel (V4A, 316L ) is258 Bioreaction engineering. used. http://buihongquan.com The stirred tank bioreactor (STR)Stainless steelStainless steel refers to various alloys of primarily iron, nickel and chromium.Molybdenum may also be added to increase the resistance of the steel tocorrosion. Stainless steels come in different grades. The commonly encounteredgrades are designated by standard codes, for example: 302 | 304 | 316 | 318In general, the higher the number, then the greater the resilience of the steel.The grade of stainless steel most widely used in the construction ofbioreactors is 316L. The L indicates the steel has a low carbon content.Stainless steels used in bioreactors are often polished to a mirror finish.This finishmakes cleaning and sterilization easier. Stainless steel components used in theconstruction of bioreactors are joined in an oxygen-free environment using aspecial technique known as TIG welding.TIG stands for Total Inert Gas and thetechnique involves the use of argon to displace the air.The presence of oxygen in the welds can cause corrosion at the weld.12/23/2018 Bioreaction engineering. 259 http://buihongquan.com The stirred tank bioreactor (STR)Standard geometryA stirred tank reactor will either be approximately cylindrical or have a curvedbase. Acurved base assists in the mixing of the reactor contents.Stirred tank bioreactors are generally constructed to standard dimensions.That is, they are constructed according to recognized standards such as thosepublishedby the International Standards Organisation and the British Standards Institution.These dimensions take into account both mixing effectiveness andstructural considerations.12/23/2018 Bioreaction engineering. 260 http://buihongquan.com The stirred tank bioreactor (STR) Standard geometryA mechanically stirred tank bioreactor fitted with • a sparger and • a Rushton turbinewill typically have the following relative dimensions:12/23/2018 Bioreaction engineering. 261 http://buihongquan.comRatio Typical values RemarksHeight of liquid in reactor to height HL/Ht ~0.7-0.8 Depends on the level of foamingof reactor produced during the fermentationHeight of reactor to diameter of tank Ht/Dt ~1 - 2 European reactors tend to be taller than those designed in the USADiameter of impeller to diameter if tank Da/Dt 1/3 - 1/2 Rushton Turbine reactors are generally 1/3 of the tank diameter. Axial flow impellers are larger.Diameter of baffles to diameter of tank Db/Dt ~0.08 - 0.1Impeller blade height to diameter W/Da 0.2of impellerImpeller blade width to diameter L/Da 0.25of impellerDistance between middle of E/W 1impeller blade and impeller bladeheightA tanks height:diameter ratio is often referred to as its aspect ratio. 12/23/2018 Bioreaction engineering. 262 http://buihongquan.comExample 1: Calculate the dimensions of the reactor A stirred tank bioreactor is ...