Surge line

Fig ure 5-2. Compressor boost capacity is limited by the surge line. 

The actual mass flow rates and speeds are corrected by factor ( /0/ ) and (l/ /0) respectively, reflecting variations in inlet temperature and pressure. The surge line joins different speed lines where the compressor s operation becomes unstable. A compressor is in surge when the main flow through a compressor reverses direction for short time intervals, during which the back... 

Performance maps These are performanee maps based on design or initial tests (base lines) of the various maehinery parameters. These maps, for example present how power output varies with ambient eonditions, or with properties of the fuel, or the eondition of the filtration system or how elose to the surge line a eompressor is operating. On these maps, the present value is displayed, thus allowing the operator to determine the degradation in performanee oeeur-ring in the units. 

The increase in compressor pressure ratio decreases the operating range of the compressor. The operating range of the compressor stretches from the surge line at the low flow end of the compressor speed line to the choke point... 

A compressor surges at certain conditions of low flow, and the compressor map, a plot of head versus flow, has a surge line defining the limits. Surge controls help the machine avoid surge by increasing flow. For an air compressor, a simple spill to the atmosphere is sufficient. For a hydrocarbon compressor, recirculation from discharge to suction is used. 

Figure 2.19 illustrates the basic controls required to keep the compressor out of surge by quickly introducing an artificial load as the surge line is approached within some limit. In order to do this, the response speed of both the flow sensor and the valve must be very fast. 

Both axial and centrifugal compressors are subject to an unstable region of low flow operation called surge. This region is defined by the pressure-flow relationship which has a peak determined by the operating speed. For various compressor speeds, these peaks may be connected to determine a surge line, which defines a region of unstable operation at lower flows. 

The manufacturer will normally supply a set of curves for each compressor section (Figure 17.7), at the design speed with further curves at +/ — 10% or +/ — 20% speed. The surge line will be marked, indicating the region of unstable operation that must be avoided. The manufacturer should also specify the polytropic efficiency. 

While this approach results in a significant improvement in computation time, the approximate solution may not be accurate enough for the application. Particularly, where control applications are concerned, these unstructured elements are related to the integral part of the control loops and an inaccurate solution may have catastrophic effects mainly if the process is highly dynamic (e.g., surge lines and radicalic systems), where the correction selection of the discretization time of the control action is also critical. 

Variable-speed driver Water droplets, dust may cause damage. No surge line... 

Boronmeters in the pressurizer surge line, makeup pumps and cleanup systems ... 

The stability of the pressure of the primary system is assured by the pressurizer (8). This is a vertical vessel whose volume is normally 60 per cent filled with water and 40 per cent by steam. The lower part of it (filled with water) is connected by a surge line with one of the two primary cooling circuits electrical heaters are immersed in the water. The upper part (filled with steam) can be sprayed by cold water. 

For that purpose, a number of studies and analyses were performed including metal samples tests, and they proved the applicability of the LBB conception. As a result, acoustic leakage control system ALUS was installed, covering also surge line DN 200 pipes, and the system shows good results. Additionally for the same purpose, two new systems of that type are now in process of qualification. 

Another information system was installed on the surge line and database was created for real time monitoring of pipe metal temperature to evaluate the possible effect of the fluid stratification. It was proven that the stratification phenomenon does not create unacceptable stresses on the pipe metal. 

Other reactor coolant system penetrations are the pressurizer surge line in one hot leg the four direct vessel injection nozzles for the safety injection system two return nozzles to the shutdown cooling system, one in each hot leg two pressurizer spray nozzles vent and drain connections and sample and instrument connections. 

THE PRESSURIZER LIQUID SAMPLE LINE IS TO TAP INTO the surge LINE AS... 

The 42-in. and 30-in. pipe diameter are selected to obtain coolant velocities which provide a reasonable balance between erosion-corrosion, pressure drop, and system volume. The surge line is sized to limit the frictional pressure loss through it during the maximum in-surge so that the pressure differential between the pressurizer and the heat transfer loops is no more than 5 percent of the system design pressure. The spray line sizing is discussed in Section 5.4.10. 

The pressurizer, as shown in Figure 5.4.10-1, is a vertically mounted, bottom supported, cylindrical pressure vessel. Replaceable direct immersion electric heaters are vertically mounted in the bottom head. The pressurizer is furnished with nozzles for the spray, surge, and safety lines, and pressure and level instrumentation. A manway is provided in the top head for access for inspection of the pressurizer internals. The pressurizer surge line is connected to one of the reactor coolant hot legs and the spray lines are connected to two of the cold legs cit the reactor coolant pump discharge. Heaters are... 

The pressurizer surge line is sized to accommodate the flow rates associated with the RCS expansion and contraction due to the transients specified in Section 3.9.1. 

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