Feed water pipes

In the previous example it was assumed that the CO boiler would receive its feed water from existing equipment. The cost of deaerators and related feed water equipment would increase the investment somewhat. Also, running feed water piping a considerable distance to the CO boiler was assumed not to be required in the example. 

All high-pressure feed water piping along with control valves to fill up the boiler shall be designed, fabricated, and erected by vendor. 

Vendor shall supply all standard fittings and valves for feed water, blowdown, vent, safety, as well as steam stop valves, instmmentation, level controllers and low-level alarms, and boiler feed water pumps with motors (optional). All of these shall be supplied with test certificates and approval of statutory authorities. Feed water piping along with bypass pipe to fill up the flash dmm directly shall be designed, fabricated, and erected by vendor. 

However, the most catastrophic cases to have happened are two cases caused by a break of a main feed-water pipe with corrosion accelerated by water flow. These happened in the Trojan power station in 1985 (368 mm pipe) and in the Surry 2 power station in 1986 (460 mm elbow). In both cases, ferritic steel with low chromium content was involved, with low oxygen water which favours the formation of Magnetite (Fc304), which is not very hard and more easUy attacked by the formation of soluble ferrous ions in an unfavourable water pH (<8.5 or >11). In the case of Surry 2, four casualties were caused by the explosion. 

The SG features an annular tube bundle with helical tubing. The steam is generated tube-side. The feed water piping is connected to two feed water headers, located symmetrically inside the reactor vessel within a calm zone, provided each with two tube plates laid out vertically. The tubes depart circumferentially from the tube plates. 

Based on experiences from Finland, other countries (including Slovakia) have changed the old feed water piping systems of the SGs in their NPPs. At this point, it is worth noting that the incident at unit 2 of the Paks NPP (Hungary, 2003) related to the cleaning of fuel assemblies in a special tank, which was necessary due to insufficient passivation of the pipelines in the SG after steam water pipe system exchange in 1997. 

The basic 1977 design was improved after 1994 by installing a new feed water pipeline system. There was also a change in the type of steel used in these pipes. Instead of conventional carbon steel, austenite steel was used in the distribution boxes as well as the feed water pipes. 

The main advantage of this approach is that a visual inspection of the feed water pipe can be performed directly due to the placement of the whole water distribution system over the primary pipe bundle. Using this system, any potential defects are easier to observe. Another advantage arises from the seven boxes with ejectors that mix the feed water with boiler water, thus decreasing the thermal load. An additional advantage is that it is possible to check and exchange of the distribution boxes if they get damaged. 

Visual inspection on 29 April 2002 focused on the heterogeneous weld, which connects a feed water pipe made of carbon steel (GOST 20K) to a new feed water pipeline system made from austenitic steel (CSN17248). Several samples were taken for MS analysis from the weld as well as the surrounding area in the form of powders or small particles (descriptions of the samples are given in Table 4.25 and Figures 4.67 and 4.68). The heterogeneous weld was well polished. 

Internal body surface, about 1 m below the feed water pipe inlet... 

In connection to the planned commissioning of Mochovce NPP 3 and 4 (announced officially on 3 October 2008), it is recommended that all feed water pipes and water distribution systems in the steam generators should be replaced immediately before starting operation with new ones constmcted from austenitic steels. The Bohimice design with feed water distribution boxes is highly recommended, and seems to be acceptable from a practical point of view. 

Feed the pipe from the exhaust manifold into a water tank with baffles as shown below. 

The gas and electrolyte mixture flows through two openings in the front plate and passes to separator where the gas is separated from the electrolyte. The gases are then washed with distilled water and led to the gas holders. The hot electrolyte flows to the coolers and after cooling passes to the lower channels of the electrolyzer and then to the individual chambers. The feeding water is brought by a funnel to the upper part of the separator where it is first used to wash the gas. The separating columns connected by an overflow pipe also act as pressure controllers. 

X Water pipes roof coverings household goods chemical equipment the arts alloys pest control inorganic dyes feed additives photography seed disinfectants fungicides algicides electroforming 111, 23, 3512, 3522,3529, 372, 4, 94... 

Fig 38 39. Here are some pictures to help you make an easy self humidifying chamber, most things to make the chamber can be obtained from local hardware shops the plastic car registration plate nuts bolts from car accessory shops. All that is needed to keep the tank humid is an air stone some tube a small aquarium air pump, Simply make a small hole near the top of the tank feed the pipe through to the water container, attach the air brick pump. The inner angled drip lids are simply shaped 2mm plastic sheet. 

The flow diagram of the installed SCWO bench scale plant (Figure I) shows that feed, water and air are pumped and compressed separately, typically to 26-30 MPa. After preheating and mixing, the reactants are fed into the pipe reactor (PR) or double pipe reactor where oxidation takes place. After cooling and gas-liquid separation, the aqueous product and the off-gas are analysed. The whole SCWO bench scale apparatus is controlled automatically. 

Feed-water Heaters.—Types include the open heater (Cochrane, Webster) in which the exhaust steam and water mix, and the closed heater, in which the water circulates in tubes surrounded by exhaust steam. Open heaters give slightly higher feed temperatures at the same back pressure, or slightly less back pressure at the same feed temperature. Filters, separators, etc., are provided to remove oil from the exhaust. The open heater forms a convenient receptacle for various drips, for the automatic introduction of any cold water make-up supply and for certain forms of feed-water treatment and purification. It may be of the thoroughfare type in which all exhaust steam in the pipe passes through the heater, or of the draw in type in which a branch from the auxiliary exhaust leads to the heater as a dead end. Open heaters must be located on the suction side of the feed pump and above (preferably 3 ft. or more above) the level of the feed-pump suction valves. 

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