Pressure balancing line

When inerts are continuously vented (e.g., vacuum condenser), it is important to prevent the vent line from choking with liquid. In one condenser, the arrangement shown in Fig. 15.10d experienced choking and instability before the pressure balance line was installed. The pressure balance line eliminated the problem. 

Flooded condenser schemes shown in Fig. 17.5a to c and f can be used instead of coolant flow variations. In such cases, the inerts normally leave finm the top of the condenser instead of the reflux drum (Fig. 17.8e). If the reflux drum is not flooded, a pressure balance line must be included otherwise, a stable pressure will be impossible to keep in the reflux drum. An overflow line should also be included in this arrangement. 

The core make-up tanks subsystem is a passive, subsystem that injects borated makeup water into the reactor coolant system. The core makeup tanks are coimected to the reactor coolant system through a discharge injection line and an inlet pressure balance line connected to a cold leg. 

The performance of pilot-operated PRVs depends on the pressure balancing line. If this line is blocked, pressure balancing between the top and bottom of the piston will not be possible, and the valve will lift at comparatively low operating pressure. This is the major disadvantage of pilot-operated valves. This type of valve can be recommended only if the operating fluid is clean. The pilot-operated valve is not very popular for hydrocarbon service. 

The second series of the EC funded project included five experiments for the investigation of the break location and CMT scaling (smaller CMT) on the PSIS behaviour. PACTEL operators made small changes to the CMT instrumentation to better detect CMT level and thermal stratification behaviour. The PSIS consisted of a Core Make-up Tank, which had connections to downcomer through an injection line and to one cold leg through a pressure balancing line. 

VIHAVAINEN, J., TUUNANEN, J. "Passive Safety Injection during SBLOCA from a Core Make-up Tank with a Pressure Balancing Line to Pressurizer Experiment in... 

Thus the ECCU always operates in complete heat balance at any desired hydrocarbon feed rate and reactor temperature this heat balance is achieved in units such as the one shown in Eigure 1 by varying the catalyst circulation rate. Catalyst flow is controlled by a sHde valve located in the catalyst transfer line from the regenerator to the reactor and in the catalyst return line from the reactor to the regenerator. In some older style units of the Exxon Model IV-type, where catalyst flow is controlled by pressure balance between the reactor and regenerator, the heat-balance control is more often achieved by changing the temperature of the hydrocarbon feed entering the riser. 

Our example system has a flow-controlled feed, and the reboiler heat is controlled by cascade from a stripping section tray temperature. Steam is the heating medium, with the condensate pumped to condensate recovery. Bottom product is pumped to storage on column level control overhead pressure is controlled by varying level in the overhead condenser the balancing line assures sufficient receiver pressure at all times overhead product is pumped to storage on receiver level control and reflux is on flow control. 

The pressure balance is off by about 21 Ib/fP. In design, this can be corrected by a slight adjustment in liquid level or by adding pressure drop to the inlet line (e.g., a valve). It is assumed here that no further trial calculations are needed. 

One important feature of Fig. 8.6 is the condensate drum balance line. Note, that this line is connected below the channel head pass partition baffle. This ensures that the pressure in the channel head, below the pass partition baffle, and the pressure in the condensate drum, are the same. If these two pressures are not identical, then the level in the condensate drum cannot represent the level in the channel head. For this reason, never connect the condensate drum vapor space to either the steam supply line or the top vent of the reboiler s channel head. 

One such turbine, in a refinery near London, would not drain properly, In order to push the condensate out of the turbine case, the operators were forced to raise the surface condenser pressure from 100 to 250 mm Hg (i.e., 20 in of mercury vacuum, in the American system). Note that the balance line shown in Fig. 8.11 keeps the pressure in the turbine case and the condensate drum, into which the turbine case is draining, both equal at the same pressure. 

SLOW PRESSURE STEAM NOZZLE SIZE DEAERATOR WATER Outlet Nozzle Size PIMP BALANCE LINE NOZZLE S I ZE/QTY. 

In the pressure-balanced design, the pressures of the main water and pilot lines are balanced at the nozzle to keep it closed. Upon activation of the system, one or more solenoid valves vent the pilot line and the pressure in the main riser opens the nozzle to cause flow. 

WATER ANO I PH. CONDENSATE NOZZLE. SI ZE 2PH. Condensate Nozzle Size 3 LOW PRESSURE STEAM NOZZLE SIZE 3 DEAERATOR wAter Outlet Nozzle Size PUMP balance LINE NOZZLE-S I 2E/QTY. DEAERATCR CRAIN NOZZLE SIZE PUMP K ICXBACK/Sparqer Nozzle Size ACCkSSCft I ES -----------------------------------... 

Figure 18 Schematics of electro-optical potential including the Casimir-Polder attraction of Eq. (48) for 87Rb atom between leads. The evanescent field, that decreases exponentially on it half wave-length expels atoms away of the surface to the location where attractive forces balance the light pressure. The line in the well cartoons the trap occupation.

A pressure balance over the complete line yields ... 

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