Water supply system main components

Based on the system requirements discussed above, fuel cell APUs will consist of a fuel processor, a stack system and the balance of plant. Figure 1-13 lists the components required in SOFC and PEM based systems. The components needed in a PEM system for APU applications are similar to that needed in residential power. The main issue for components for PEM-based systems is the minimization or elimination of the use of external supplied water. For both PEM and SOFC systems, start-up batteries (either existing or dedicated units) will be needed since external electric power is not available. 

Besides the main components, particular emphasis was placed on the essential subsystems/peripherals/balance-of-plant, including utility and auxiliary subsystems (instrument/operating air supplies, nitrogen supply, demineralised water/KOH systems, ventilation, etc.), process and safety control subsystems, and extensive test data acquisition subsystems. Also power conditioning (converters and inverters) as a way of improving the operability and efficiency of the overall system was considered. Some of the integration issues investigated in detail were ... 

The cold water feed can be provided by direct coimec-tion to the mains (in which case all components must be able to withstand mains pressure) or from a feeder tank (which is in an elevated position and filled from the mains through a float valve similar to the water closet-cistern float valve). For mains pressure systems most utilities or water supply authorities require the installation of a nonreturn valve. Whereas low pressure (feeder tank) systems are open to the atmosphere through a vent pipe, mains pressure systems must be protected against overpressure (due to thermal expansion of water as heated) by a pressure relief valve, as well as against collapse (implosion), which could be caused by a suction effect (vacuum formation) in case of an aceidental water discharge, by an air intake (or breather) valve. 

The major auxiliary systems of SMART consist of a component cooling system (CCS), purification system and make-up system. The function of the CCS is to remove heat generated in the main coolant pumps (MCPs), control element drive mechanisms (CEDMs), pressurizer (PZR), and the internal shielding tank. Feedwater supplied from the condensate pump of the turbo-generator is used as the coolant to remove heat. The purification system purifies the primary coolant and controls water chemistry to provide reliable and safe operation of the reactor core and all equipment in any mode of operation. The make-up system fills and makes-up the primary coolant in case of a primary system leak and supplies water to the compensating tanks for the PRHRS it consists of two independent trains, each with one positive displacement makeup pump, a makeup tank, and piping and valves. 

Most release units can also send back a response, allowing a two-way hydroacoustic link to the OBS, e.g., to determine the distance to the system, to ask for state of health, or to send simple commands. Some research vessels are equipped with permanently installed transducers, but more often, mobile transducer systems are used on board. For the mobile units, the ship has to stop and the transducer lowered into the water to achieve a coupling of the acoustic signal to the water column. The hydroacoustic signal uses frequencies between 5 kHz and 20 kHz with different modulation techniques. Normally, the signal is coded each unit uses unique codes for release and other commands. Because the release unit is the central component to recall the OBS, its power supply is usually completely independent from the main system. Some models even use... 

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