Low pressure condenser

Figure 4 shows high-pressure condensate (small line) being added to low-pressure condensate without the usual troublesome hammer. The high-pressure condensate has a chance to cool before emerging into the low-pressure condensate line. 

Figure 4. Method for adding high-pressure condensate to low-pressure condensated without troublesome water hammer.

Often in plant operations condensate at high pressures are let down to lower pressures. In such situations some low-pressure flash steam is produced, and the low-pressure condensate is either sent to a power plant or is cascaded to a lower pressure level. The following analysis solves the mass and heat balances that describe such a system, and can be used as an approximate calculation procedure. Refer to Figure 2 for a simplified view of the system and the basis for developing the mass and energy balances. We consider the condensate to be at pressure Pj and temperature tj, from whence it is let down to pressure 2. The saturation temperature at pressure Pj is tj. The vapor flow is defined as V Ibs/hr, and the condensate quality is defined as L Ibs/hr. The mass balance derived from Figure 2 is ... 

This equation expresses the fraction of the high-pressure condensate returned as low-pressure condensate. The input information needed to apply the working equation are tj and P[. Values for h can be approximated from the following ... 

For moderate-temperature and low-pressure condensers, such as vacuum surface condensers (see Chap. 18), a single pass on the tube side is not uncommon. These exchangers are typically fixed-tubesheet... 

Low pressure, Condenser. In this H/Ex, hot flash vapor refrigerant condenses and cools on one side of the condenser, and condenser water, returning to the cooling tower, is on the other side. 

Sulfur dichloride decomposes at its boiling point. It is best distilled at low pressure, condensing it in a cooled vessel. ... 

A split-range control-system is normally used for an overhead low-pressure condenser (see Fig. 2). In this setup. Valve A controls makeup gas to the accumulator, and Valve B releases excess pressure. Valve A opens or closes according to a preset system pressure, delivering makeup gas whenever needed. 

As a rough approximation, the same relative reduction in low-pressure condensing coefficients due to noncondensable gases can also be applied to higher pressures. 

High-temperature, high-pressure steam is generated in the boiler and then enters the steam turbine. At the other end of the steam turbine is the condenser, which is maintained at a low temperature and pressure. Steam rushing from the high-pressure boiler to the low-pressure condenser drives the turbine blades, which powers the electric generator. Steam expands as it works hence, the turbine is wider at the exit end of the steam. The theoretical thermal efficiency of the unit is dependent on the high pressure and tanperature in the boiler and the low temperature and pressure in condenser. 

The steam flash drum is a device for steam recovery. Flash steam occurs at the drum where steam condensate or boiler blowdown experiences a drop in pressure causing some of the condensate or boiler blowdown to evaporate forming steam and thus produces steam at the lower pressure (Figure 15.11). For low-pressure condensate, flash steam is negligible and thus it is not worth to recover. However, for medium-and high-pressure condensate, it is important to recover flash steam. 

For moderate-temperature and low-pressure condensers, such as vacuum surface condensers (see Chap. 25), a single pass on the tube side is not uncommon. These exchangers are typically fixed-tubesheet designs. Such exchangers are fine from a purely process point of view. However, there is no practical way to disassemble the exchanger to clean the outside (i.e., the shell side) of the tubes. This inability to clean the shell side frequently leads to tremendous loss of efficiency after the condensers foul. 

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