Heater drains pumps

The first reason was that this Government-funded project had cut comers to save money - power stations depend on everything working, so any normal power station would have two Condensate Extraction Pumps to pump water out of the turbine condenser, two Heater Drains Pumps to pump water through the feed heaters, and two Main Boiler Feed Pumps to drive water into the boilers. Each of the pumps could do the job by itself, but a redundant spare would normally be provided to ensure overall plant reliability. However, at PFR we only had one of each. This will have saved a lot of money during constmction, but it had been a false economy, since one failure meant the whole power station stopped making electricity. 

The condenser is cooled by the circulating water system which typically incorporates three electrically driven pumps loss of one pump will call for a power reduction, but will not yield a turbine trip in the short term. The condensate is pumped forward to the dearator (or the feedwater tank) through low pressure heaters and a condensate cleanup system with ion exchange filters by means of three 50% condensate pumps. The drmnage from the heaters is pumped forward through the cleanup system by means of a dedicated low pressure drain pump. 

The condenser is of the surface, twin pass type. It is of a twin shell construction. There are two deaerators that utilize extraction steam from the low pressure turbines, five low pressure feedwater heaters that utilize extraction steam from the low pressure turbines, three high pressure heaters that utilize extraction and exhaust steam from the high pressure turbine, three one-half-sized condensate pumps and condensate booster pumps, and three one-half-sized feedwater pumps. Heater drains from the three high pressure feedwater heaths are cascaded to the deaerator, drains from the five low pressure heaters are cascaded to the condenser. 

The steam produced in the reactor pressure vessel is directed to the high-pressure part of the turbine downstream, the condensate formed on the high-pressure turbine is separated and directed to the heater drains. The residual steam powers the low-pressure part of the turbine and, finally, is completely condensed in the main condenser. The main condensate is purified in the condensate demineralizers where corrosion products and ionic impurities are retained. The feedwater then is recycled via preheaters to the reactor pressure vessel. In older BWR plants, all the condensates are purified in the condensate polishing system in the newer, forward-pumped plants only the main condensate is purified there, while the heater drains are directly pumped to the feedwater tank. In some of the BWR plants the feed-water tank is equipped with an electromagnetic filter for removal of suspended corrosion products (mainly iron oxides). 

Law, R. J., Indig, M. E., Lin, C. C., Cowan, R. L. Suppression of radiolytic oxygen produced in a BWR by feedwater hydrogen addition. Proc. 3. BNES Conf Water Chemistry in Nuclear Reactor Systems, Bournemouth, UK, 1983, Vol. 2, p. 23-30 Lin, C. C. Chemical behaviour and distribution of volatile radionuclides in a BWR system with forward-pumped heater drains. Proc. 3. BNES Conf. Water Chemistry in Nuclear Reactor Systems, Bournemouth, UK, 1983, Vol. 1, p. 103—110 Lin, C. C. Chemical behaviour and steam transport of nitrogen-13 in BWR primary systems. 

In BWR plants with forward-pumped heater drains, however, a large fraction of the iodine and other non-gaseous fission products carried by the primary steam is directly returned to the reactor water without passing the condensate polishing system. When calculating source strengths from the activity concentrations in the reactor water, the fission product input with the feedwater has to be taken into account as an additional source for the reactor water (Lin, 1983). 

Lin (1983) also reported on a detailed investigation of the distribution of iodine volatilized from the reactor water in BWR water—steam circuits with forward-pumped heater drains. In this plant design, only the main condensate is directed to the condensate polishing system, whereas the different drains from the turbine are fed directly back to the feedwater tank. Under such plant conditions, about 75% of the iodine carried by the main steam flow is precipitated together with the condensate in the moisture separator downstream from the high-pressure part of... 

Lin, C. C. Chemical behaviour and distribution of volatile radionuclides in a BWR system with forward-pumped heater drains. Proc. 3. BNES Conf. Water Chemistry of Nuclear Reactor Systems, Bournemouth 1983, Vol. 1, p. 103-110... 

In the GE model, differences in the characteristics of the corrosion product particulate material are emphasized in detail they are considered to arise from the different types of condensate cleanup systems (powdex or deep-bed) employed in the plants and from the option of forward-pumped heater drain systems. The model includes many empirical coefffcients obtained through laboratory experiments and, above all, by the aid of a large number of data from measurements at operating BWR plants. For this reason, the model is mainly applicable to plants of GE design (Alder et al., 1992). 

In the turbine system design, the TCDF-38 system composed of a single high-pressure turbine and single low-pressure turbine is adopted for the 300 MW(e) RMWR with the cascade heater drain system and without the moisture separator-reheater. This is because system simplification takes priority over improvements in the thermal efficiency. Furthermore, redundancy in the condensate and feedwater system (i.e., back-up pump and heater train) is eliminated because the risk of electric generation loss is lower in the small power plant. 

The reservoir may be either pressurized or atmospherie. It must have suffieient eapaeity to eontain all oil during drain-baek or shutdown. It must be equipped with an oil level indieator, a low-level alarm switeh, safety relief valve, a pump for oil makeup during operation, drain valve, heater, mist eliminator, strainers, and required valves. Expander reservoirs must be designed and eonstrueted in aeeordanee with applieable ASME eodes. Reservoir retention time is typieally between 5-18 min depending on turboexpander size and manufaeturer s sizing eriteria. This is an area where the owner/purehaser should ask for the manufaeturer s assistanee. 

Many systems are shut down for periods of the year, either for process closure or if not required in winter. The advice of the supplier should be sought as to the correct procedure. In the case of refrigerant circuits, it is advisable to pump down into the receiver or condenser to minimize leakage losses. Water towers should be drained in winter in this climate, if not in use, and the tank heater disconnected. 

The reaction mixture is pumped away from the reactor with an alkymer transfer pump, through a steam heater and an orifice mixer into the alkymer wash and surge tank. Dilute caustic solution is recirculated from the a.w.s. tank through the orifice mixer. Makeup of caustic is from a dilute caustic storage tank. Spent caustic is intermittently drained off to the sewer. The a.w.s. tank has an internal weir. The caustic solution settles and is removed at the left of the weir the alkymer overflows the weir and is stored in the right-hand portion of the tank until amount sufficient for charging the still has accumulated. 

The schemes with natural reflux are operated based on the principle of natural convection (i.e. circulation based on density difference between cold and heated fluid streams) to create a thermo-siphon. The hotter stream has the lower density. In natural reflux, the heated feed passes to the top of the heat exchanger and then to the bottom of tower by itself while the colder stream drains from the tower bottom to the heater. Forced reflux is based on using pumps for the circulation. 

Cabin climate control is a substantial energy drain that may account for 25% or more of the energy consumption in an EV. The flexible nature of the electric systems allows a number of temperature control alternatives ranging from positive temperature coefficient heaters to heat pumps for heating and cooling. 

The washed negative plates are loaded in a pressure ehamber equipped with heaters. The latter cause the temperature of the plates to rise above the boiling point of water. The pressure chamber is equipped with a condenser unit where the water vapours are liquefied and drained out. When the pressure chamber is loaded with plates, a vacuum pump is turned on and, after a definite vacuum level is reached, the heaters are turned on, too. The plates are dried for quite a long time (20—24 h) and when no more water condense forms, heating is stopped and the coohng system is turned on. When the temperature in the chamber reaches room temperature, the vacuum pump is stopped. This method is efficient, but too slow and expensive. 

Figure 20 Principle of a venting filter for in situ integrity tests. The integrity tests are carried out following the water intrusion method 1, primary filter with an 0.22 pm cartridge 2, secondary filter with an 0.22 pm cartridge installed as a backup filter, sterilized independently of the filter 1 3, test liquid reservoir (WFI) with heater 4, inlet valve for test liquid (WFI) 5, pure steam inlet 6, filtered air (5 bar absolute) 7, venting gas (1060 mbar) 8, drain line with valves 9, to water ring pump (WRP) 10, to condenser 11, to chamber 12, sanitary valves 13, temperature sensors.

Next, the feedwater enters a de-aerator where dissolved oxygen is removed. From the de-aerator, the feedwater is pumped to the steam generators through two high-pressure feedwater heaters, each incorporating drain cooling sections. 

Within the isothermal expansion at the temperature Tq the system is draining off the heat AQo being pumped out, transferred from the cooler B. This heat is, within the isothermal compression at the temperature Tw, delivered from into the heater A. We call it the output heat AQvv,... 

Preparation for Lay-Up. When a boiler is being cleaned in preparation for lay-up, the water side of the unit should be cleaned and then the unit should be fired to drive off gases. The fire side should then be cleaned. An oil coating on the fire-side metal surfaces is beneficial when the boiler is not used for extended periods of time. Another helpful treatment would consist of completely filling the boiler with an inert gas and seating it tightly to prevent any leakage of the inert gas. This will help prevent oxidation of the metal. Fuel-oil lines should be drained and flushed of residual oil and refilled with distillate fuel. H all boilers are to be laid up, care of oil tanks, lines, pumps, and heaters is similarly required. 

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