啤酒锥形发酵罐冷带设计与应用

啤酒锥形发酵罐冷带类型和面积影响发酵过程温度控制，而温度高低、麦汁浓度下降快慢和发酵时间长短，三者相互制约，从而影响啤酒的质量。将从啤酒锥形发酵罐冷带设计和应用进行探讨。     

外循环气升式发酵罐体积溶氧系数及其应用于柠檬酸发酵的研究

对10L外循环气升式发酵罐的体积溶氧系数进行了研究，得出了体积溶氧系数与操作条件之间的关联式。在此基础上，进行了柠檬酸发酵试验，并与10L机械搅拌发酵罐进行比较，实验结果表明，研制的外循环气升式发酵罐的发酵结果优于机械搅拌发酵罐。因此，外循环气升式发酵罐用于柠檬酸的发酵生产具有较好的前景。     

Analysis of acetic acid productivity in a continuous two‐stage bioreactor with cell recycling

The performance of a two‐stage system with cell recycling and fresh feed at each stage is studied numerically for continuous acetic acid production. In this system, both filtrate and bleed broth from the first stage are supplied to the second fermenter. At high substrate conversions, this configuration is found to provide higher acetic acid productivities than either a previous configuration where only the first‐stage bleed broth is fed to the second stage or a single recycle chemostat at the same bleed ratios. Copyright © 2005 Society of Chemical Industry     

Optimization of pullulan production from synthetic medium by Aureobasidium pullulans in a stirred tank reactor by response surface methodology

The production of pullulan from synthetic medium by Aureobasidium pullulans P56 in a stirred tank fermenter was investigated. The kinetics of polysaccharide, pullulan and biomass production was determined. Response surface methodology was used to investigate the effects of three factors (initial sugar concentration, aeration rate and agitation speed) on the concentration of pullulan in batch cultures of A pullulans. In the experiments, the range of values used for the three variables described were; 30–70 g dm^?3 initial sugar concentration, 200–600 rpm agitation speed and 1.0–3.0 vvm aeration rate. No previous work has used statistical analysis in determining the interactions among these variables in pullulan production. Results of the statistical analysis showed that the fit of the model was good in all cases. Aeration rate, agitation speed and sugar concentration had a strong linear effect on pullulan concentration. Moreover, pullulan concentration was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions with the exception that the interaction between agitation speed and aeration rate was insignificant (P > 0.05). Maximum pullulan concentration of 17.2 g dm^?3 was obtained at the optimum levels of process variables (initial sugar concentration 51.4 g dm^?3, aeration rate 2.36 vvm, agitation speed 345.3 rpm). These values were obtained by fitting of the experimental data to the model equation. Scanning electron microscope (SEM) photographs of polysaccharide particles containing different concentrations of pullulan were also taken to observe the morphological differences of the samples. Copyright © 2005 Society of Chemical Industry     

Comparison of lipase production by Geotrichum candidum in stirring and airlift fermenters

The production of lipase by Geotrichum candidum in both, stirred tank and airlift bioreactors were compared. G candidum an imperfect filamentous fungus, grows well in liquid medium, and produces a lipase with specific affinity for long‐chain fatty acids with cis‐9 double bonds but, lipase production is generally not efficient because the optimum medium composition and fermentation conditions are not known. Response surface methodology was used to optimize the agitation speed (100–500 rpm) and aeration (0.2–1.8 vvm) for production of lipase by G candidum in a bench‐scale stirred fermenter. A Central Composite Rotatable Design (CCRD) was used to optimize lipase activity and productivity. Lipase production in an airlift fermenter was also studied with aeration ranging from 1 to 3 vvm. A previously optimized culture medium containing 3.58% of peptone, 0.64% of soy oil and an initial pH of 7.0, was used in the experiments, incubating at 30°C. In the stirred reactor the optimum conditions of agitation and aeration for lipase production and productivity were 300 rpm and 1 vvm, leading to an activity of 20 U cm^?3 in 54 h of fermentation and 0.3900 (U cm^?3 h^?1) of productivity. The best aeration condition in the airlift fermenter was 2.5 vvm, which yielded similar lipase activity after 30 h of fermentation, resulting in a productivity of 0.6423 (U cm^?3 h^?1). In the absence of mechanical agitation similar lipase yields were achieved but in less time, resulting in productivity, about 60% greater than in a stirred fermenter; the lower energy demand for the same lipase yield offers economic advantages. Copyright © 2004 Society of Chemical Industry     

Liquid circulation time in concentric-tube airlift columns with non-newtonian fermentation broths

Liquid circulation times were measured in a 40-dm³ concentric-tube airlift fermenter with simulated media over a wide range of rheological properties. Circulation times decreased with increasing shear-thinning, and the influence of draft-tube geometry on circulation time was found to depend on the shear-thinning of the media. A semi-theoretical correlation for both Newtonian and non-Newtonian fermentation media was developed.     

Performance characteristics of a tower fermenter with mechanical foam control

For a bubble column (BC) treating foaming liquids, the characteristics of a rotating-disk mechanical foam-breaker (MFRD) fitted to the BC were examined. The foaming behaviour of the BC and the foam-breaking behaviour of the MFRD under various operating conditions were related to the changes in liquid hold-up in the foam. The gas hold-up in a mechanical foam-control system (MFS) with the MFRD was confirmed to be greater than the gas hold-up in a non-foaming system (NS) including antifoam agent (AF). Comparison of the volumetric mass transfer coefficient between the MFS and the non-foaming system, in terms of the specific power input, also demonstrated the superiority of mechanical foam control for oxygen transfer performance.     

化工过程的非线性内模控制策略（Ⅱ）─—发酵过程

针对连续发酵过程，建立了基于非线性内模控制策略的调节器设计方法．当分别用稀释速率和加料基质浓度作为操作变量以控制产品产率时，通过仿真评价了所构成系统的品质指标．仿真实验结果表明，非线性内模控制策略可以用于发酵过程的控制，并具有良好的鲁棒性．     

环流反应器中肌苷发酵液的氧传递研究

根据肌苷发酵过程主要是溶氧传质控制的结论,本文研究了操作变量和装置结构变量对环流发酵反应器中氧传递的影响,定量地得到气含率,液体循环速度和结构因素对氧传递的关系。对发酵反应器中溶氧浓度分布进行了摸拟计算,依据计算的结果提出了较佳的 D_E/D 和 L_E/D 的结构。     

重组毕赤酵母产a-葡聚糖酶甲醇流加控制的研究

本文在摇瓶发酵的基础上,利用5L发酵罐进行重组毕赤酵母甲醇诱导产Ⅸ．葡聚糖酶发酵条件的优化。结果表明,菌体湿重250g／L时开始诱导,诱导表达阶段溶氧控制在10％～20％,甲醇诱导90h时仪．葡聚糖酶酶活达330U／mL。