Down-pumping

Shut down pump and remove scale or deposits. 

FIG. 18-22 Typical draft tube circulator, sbown bere for down-pumping mode for tbe impeller in tbe draft tube. 

Alarms are used to alert operators of serious, and potentially hazardous, deviations in process conditions. Key instruments are fitted with switches and relays to operate audible and visual alarms on the control panels and annunciator panels. Where delay, or lack of response, by the operator is likely to lead to the rapid development of a hazardous situation, the instrument would be fitted with a trip system to take action automatically to avert the hazard such as shutting down pumps, closing valves, operating emergency systems. 

Down-pumping axial flow impellers are more appropriate for most particle-suspension operations (Perry and Green, 1984). Typical dimensional ratios are DT/Da = 2-3.3, and Za/DT = 0.25-0.5. The power can be calculated as in the case of liquid agitation (see eq. (3.107)) (Perry and Green, 1984). 

In the experiments described thus far, the pump laser simply populates the intermediate excited state. The consequence is that the experiment becomes a means to study that excited state. Often we are more concerned with learning about the ground state than about excited states. For this purpose, it is useful to prepare a vibrational wavepacket of that ground state. One useful means to do this is to excite the species of interest to an allowed excited state and then to down-pump from that excited state back to the ground state, with a pulse that generates a packet rather than a stationary state. The simplest way to do this currently seems to be to raise the power level of the pulsed pump laser [26]. This process is shown schematically in Fig. 7. 

Problem 4 Pump pressure shuts down pumping. 

The high-vacuum plant (the scheme of the vacuum part is in Fig. 1) was used to study hydrogen permeability of titanium nitride. The plant comprise three-stage system of the rollout (roughing-down pump and two ion pump NORD-lOO, NORD-250), system of hydrogen supply and refinement (the electromagnetic valve V10 the cylinder with unrefined hydrogen silver-palladium filter FI the volume... 

Finger flanges have been modified to meet the requirements of elderly people who suffer from arthritis or rheumatism. Actuators can be adapted to deliver drug formulations to animals for veterinary purposes or for preclinical studies. Delivery systems can be fitted out with an upside down pump, which allows actuation in upright and upside down position. 

A modern high efficiency gas-liquid STR commonly consists of a radial gas dispersing impeller in combination with one or more axial down-pumping impellers, as seen in Fig. 2. The type and number of open impellers used in the tank depend on the gassed liquid height and the media viscosity (see Table 4). Recommended axial impellers are 45° four-bladed pitch blade turbines... 

Fig. 9 Relative power demand for a down-pumping 45° pitched-blade turbine. (From Refs. " l)...

Hari-Prajitno, H. Mishra, V.I. Takemaka, K. Bujalski, W. Nienow, A.W. McKemmie, J. Gas-liquid mixing studies with multiple up and down pumping hydrofoil impellers power characteristics and mixing times. Can. J. Chem. Eng. 1998, 76, 1056-1068. 

Injection downward into the impeller at about Z>/4 from the centerline of the impeller shaft and G/D above the impeller midplane. High-efficiency three-blade down pumping turbine. 

The propeller rotates clockwise in a down-pumping mode. The vessel (glass beaker) has a diameter of 7.2 cm and the fluid height is 6.5 cm corresponding to a stirred volume of 264 cm. The same fluid as the one considered in the coaxial mixer experiments was used. The rotating speed and the volume concentration of the particles were varied in order to investigate the... 

Extensive analysis and experimentation on dip-pipe design has been carried out by Penney and co-workers (Jo et al. 1994), and the reader is referred to this work for specific design recommendations for diameter and flow rate. Their recommendations are summarized in Table 6-3 for six-blade flat-blade and three-blade high-efficiency down-pumping impellers. These recommendations should be followed to prevent dip-pipe back-mixing, enhance local blending, and prevent solids plugging. 

High-efficiency three-blade down-pumping turbine. 

Jaworski Z., Nienow A.W., Oyster K.N.. An LDA Study of the turbulent Flow Field in a baffled Vessel Agitated by an Axial, Down-Pumping Hydrofoil Impeller, Can. J. chem. eng. 74 (1996)... 

Rinse column and shut down pump and lamp. 

Down-pumping axial flow impellers are more appropriate for most paiticle-suspension operations (Peiiy and Green, 1984). Typical dimensional ratios are = 2-3.3, and... 

Install a high-pressure interlock on V-101 to shut down Pumps P-101 A/B 2. Develop upgraded procedures and training so that the operators can respond to high pressure in V-101 3. Evaluate the feasibility of upgrading the MAWP of V-101 to 280 psig... 

---