Blade Turbines water cooled

Figure 9-23. Water-cooled turbine blade. (Courtesy General Electric Company.)...

A fermentation broth contained in a batch-operated, stirred-tank fermentor, with a diameter D of 1.5 m, equipped with a flat-blade turbine with a diameter of 0.5 m, is rotated at a speed N= 3 s. The broth temperature is maintained at 30 °C with cooling water at 15 °C, which flows through a stainless steel helical coil, with an outside diameter of 40 mm and a thickness of 5 mm. The heat evolution by biochemical reactions is 2.5 x 104kJ h 1, and dissipation of mechanical energy input by the stirrer is 3.5 kW. Physical properties of the broth at 30 °C density p = 1,050 kg m , viscosity p — 0.004 Pa s, specific heat cp = 4.2kj kg-1 °C-1, thermal conductivity k = 2.1 kj h 1 m 1 °C 1. The thermal conductivity of stainless steel is 55kJh-1m-loC-1. 

Siiica S1O2 Scale in boilers and cooling water systems Insoluble turbine blade deposits due to silica vaporization Hot process removal with magnesium salts adsorption by highly basic anion exchange resins, in conjunction with demineralization distillation... 

The condensing steam turbine has a relatively low thermal efficiency because about two-thirds of the steam enthalpy is lost to cooling water in the condenser. Expensive boiler feedwater treatment is required to remove chlorides, salts, and silicates, which can be deposited on the blades causing premature failure. The blades are already under erosion conditions because of water drops present in the condensing steam. Even with these disadvantages, the condensing turbine is still selected, especially in a process that requires very large compressor drivers and relatively low amounts of process steam. 

Silica SiOj Results in the formation of scale in boilers and cooling water systems, can produce insoluble scale on turbine blades due to silica vapori2ation in high pressure boilers (usuallu over 600 psi). 

Accident evaluations specific to the GT-MHR confirmed that the passive safety characteristics of the previous steam cycle modular high temperature gas-cooled reactor designs were maintained. Events initiated by one or more turbine blade failures were assessed. It was found that the resulting differential pressure forces across the prismatic core did not exceed the allowable graphite stresses. Since the dominant risk contributor for the steam cycle design were initiated by water ingress from the steam generators, the GT-MHR is expected to have a lower risk profile to the public. References 4 and 5 provide more information on the GT-MHR safety evaluations. 

Transient overloads create damage which can cause premature failure they thus need to be considered during the design stage. If these cannot be eliminated by design then the tests should be carried out to determine the reduction in life. Examples of such overloads include water hammer in cooling pipes (as above) and gust turbulence for wind turbine blades. 

Phenolic resins are typically made by the batch process in a stainless steel reaction kettle that is jacketed for steam or cooling water and equipped with a turbine blade or an agitator for stirring and a condenser. Molten phenol and formalin, typically 37-50 wt% formaldehyde, are charged into the kettle and agitation begun. 

---