Circulating pumps used

This external recirculation loop is operated with a solution that has been clarified, that is, from which crystals have been removed. This is performed in order to prevent secondary nucleation in the external recirculation loop, which now has the higher resistance level due to the heat exchanger used there. If no crystals are suspended in this external loop, it is not possible for the circulation pump used there to produce secondary nuclei. However, the statement that this solution is free of crystals is only partially correct In fact, in the clarification zone of a DTB crystallizer, the main mass of the crystals has indeed been separated out of the solution by sedimentation, but the finer crystals (fines) and the crystal nuclei with settling rates greater than upstream velocities are not separated out. The sum total of these... 

Chemical pumps Built to handle abrasive and corrosive industrial materials. They can be of either centrifugal or positive displacement type. Circulator pumps Used to circulate fluid through a closed or looped system. They are usually centrifugal pumps, but a few use positive displacement technologies. 

For circulating water through a refractometer any commercial water circulating pump may be used.J... 

In extremely cold environments, engines can quickly become difficult, sometimes nearly impossible, to start. If ordinary gasoline- or diesel-oil-fired heaters are used, the coolant circulation pump, air fan, etc, must be powered from the vehicle s batteries, thus curtailing the time the system can be used, especially at very low temperatures when it is needed the most. By adding PbTe thermoelectrics to such heater systems, about 2% of their thermal output can be turned into electricity to mn the heater s electronics, fuel pump, combustion fan, and coolant circulation pump, with stiH sufficient power left over to keep the vehicle s battery fliUy charged. The market for such units is in the hundreds of thousands if manufacturing costs can be reduced. 

Forced Circulation System—Using foreed eireulation in a waste heat reeovery system allows the use of smaller tube sizes with inherent inereased heat transfer eoeffieients. Flow stability eonsiderations must be addressed. The reeireulating pump is a eritieal eomponent from a reliability standpoint and standby (redundant) pumps must be eonsidered. In any event, great eare must go into preparing speeifieations for this pump. 

A low-pressure-drop liquid cyclone is sometimes used to clarify liquor discharged from the evaporator. The driving force is the pressure drop across the circulating pump. Thickened slurry is returned through a wide-open cyclone underflow connection to the circulating piping before the pump suction. 

Failure of the integrity of the DjO system in sequence 5 resulted from a small leak in the DjO system and failure of the operating personnel to isolate the leak which dominated the sequence. The probability of the small leak that challenges of the tank used to pressurize seals for the main circulating pumps was estimated to be 0.5 0.21 g. 

As long as the circulation pump was kept running, water could not settle out in the dead-end. The foreman knew the pump had to be kept running. When he was transferred to another plant, this information was lost, and the pump was used only for emptying the tank. 

The second area will be feedwater pumps. It is normal to have a duplicate standby feedwater pump. Sometimes this may be two for each boiler or one duplicate pump to serve any selected boiler. These will usually require manual changeover in the even of failure of the duty pump. It is practical to automate this changeover by using pressure sensors and motorized valves. The same can apply to oil-circulating pumps, gas boosters, water-treatment plant and any other valves and motors. It is possible to do most things, but in the end there is the cost to be considered. An... 

The circulation pump should be a centrifugal type with a plastic or PVC impellor, or cast iron with adequate corrosion inhibitor. The acid tank, hoses, and other equipment should be connected to and from the boiler using suitable connection points. This usually is the bottom BD connection (with the valve removed) and the open manhole as the top point. 

New systems or processes may also need to be qualified from an operational safety perspective. This is particularly relevant in the case of chemical synthesis involving exothermic reactions. Critical safety aspects are usually identified using hazard operability or HAZOP assessments and studies. For example, a HAZOP analysis of an exothermic reaction vessel would involve consideration of the consequence of failure of the motors for mixers or circulation pumps for cooling water. Thus, the qualification of such a system would involve checks and assessment to ensure that the system/process can be operated safely and that pressure relief valves or other emergency measures are adequate and functional. 

The catalyst for the in situ FTIR-transmission measurements was pressed into a self-supporting wafer (diameter 3 cm, weight 10 mg). The wafer was placed at the center of the quartz-made IR cell which was equipped with two NaCl windows. The NaCI window s were cooled with water flow, thus the catalyst could be heated to 1000 K in the cell. A thermocouple was set close to the sample wafer to detect the temperature of the catalyst. The cell was connected to a closed-gas-circulation system which was linked to a vacuum line. The gases used for adsorption and reaction experiments were O, (99.95%), 0, (isotope purity, 97.5%), H2 (99.999%), CH4 (99.99%) and CD4 (isotope purity, 99.9%). For the reaction, the gases were circulated by a circulation pump and the products w ere removed by using an appropriate cold trap (e.g. dry-ice ethanol trap). The IR measurements were carried out with a JASCO FT/IR-7000 sprectrometer. Most of the spectra were recorded w ith 4 cm resolution and 50 scans. 

Simple pumps for circulating gas or liquid can be made using two valves with a chamber between them. One ingenious pump uses a heat engine (A. R. Pearson and J. S. G. Thomas, 1925). The hard glass or silica bulb A (Figure 80, T) contains air initially at atmospheric pressure. This is heated with tap T closed and when the... 

Friction reducers such as partially hydrolyzed polyacrylamide may also be used in drilling fluids (19). They allow fluid to be circulated through the well bore more easily thereby reducing horsepower requirements for the circulating pumps and thus decreasing well treatment costs. 

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