Feed water pump

If the d-a tank should be. sealed and artificially pressurized with steam gas (sometimes they are, or should be), then each 10 psi adds 23.1 ft of artificial head to the. sy.stem s NPSHa. If the boiler feed water pump has a NPSHr of 30 ft at the duty point, now you can see why boiler feed water pumps are sometimes considered problematic regarding eavitation. This also demonstrates the need to seal and artifieially pressurize d-a tanks to get the NPSHa above the NPSHr of the pump. 

The on-line feed water pump tripped, but the operator ignored the alarm signal, presumably because he thought the backup pump w ould start up automatically. 

Figure 3-59. Typical temperature rise for boiler feed water pump. (By permission, Transamerica Delaval Engineering Handbook, 4th ed., H. J. Welch, ed., 1983, Transamerica Delaval, Inc., IMO Industries, Inc., Div.)...

Boiler feed water pump, 194 Calculations, 189-191 Corrections, 192, 193 Required by pump, 180, 181, 182,188-190 Newton s lavs, chart, 226 NFPA Codes, 398... 

A less common type of fuel-gas trip to a heater is a low-pressure trip. A pressure transducer generates a milliamp output from a boiler feed-water pump. Should this milliamp output fall below a certain level, the... 

In the secondary loop, a feed water pump circulates water through a heat exchanger where the primary and secondary loops exchange heat. The water in the secondary loop is turned to steam here and feeds a turbine, where electricity is generated. In the boiling-water reactor, there is only one loop, and as a result, the overall efficiencies are higher at the added expense... 

Steam turbines. In modern plants the centrifugal synthesis gas compressors, including recycle, are almost exclusively driven by a steam turbines. These are generally extraction turbines with a condensing section. Steam is extracted at suitable pressure levels (e.g. 45-55 bar) to provide, for example, the process steam in steam reforming plants, and for other drivers, e.g., air compressor, ammonia compressor, boiler feed water pumps, and blowers. 

Mechanical energy consumption 14.6 MW (preparation system, mills and feed-water pump are steam turbine driven)... 

The accident at TMI-2 was initiated at 4 am by a minor malfunction, or transient, in the non-nuclear part of the reactor. The main feed-water pumps stopped running, caused by either a mechanical or electrical failure, which prevented the steam generators from removing heat. This minor event would... 

Secondary circuit water boiling up and abrupt increase of heat removal from the primary coolant occurs to result probably in its freezing. Steam turbine drive of feed water pump and by-pass pipelines connecting steam generator inlet and steam header through orifices are provided in the secondary circuit to decrease consequences of such accidents. 

The water leak rate increases as the tubes break, but is limited by the feedwater pump capacity. After the water leak rate reaches the peak value, the main steam pressure decreases because the turbine trips due to the reduction of the main steam flow rate, and the feed water pump trips due to the reduction of its rotational firequency. Due to these quasipassive features, the water leak rate decreases and adverse consequences can be avoided by providing two pressure relief pipings with rupture disks at Ae bottom of the steam generator which operate at a pressure of 11 kg/cm. ... 

Waste Heat Recovery Boilers, Economisers,and Boiler Feed Water Pump... 

A sulfuric acid plant generally produces more steam than it can consume internally. The excess steam can be used for generating power or for driving certain equipment like the main air blower, boiler feed water pump, etc., by steam turbines. The turbines could be condensing, backpressure, or extraction types. 

Some of the plant drives are running on power purchased from external sources and some on steam turbines/power produced internally, e.g., the air blower, boiler feed water pumps, etc., can be run on steam turbines directly while other pumps are run on external power. 

Waste heat recovery boilers and economisers, feed water pumps, and safety valves ... 

The boiler is upstairs. There is no hoist to take up the bags of raw material. The bags are being taken up manually. Reactor and boiler cannot be observed easily from control room. Boiler feed water pump is behind the BFW tank and cannot be observed. Only one escape ladder (right hand side) can be used, but quick escape is difficult (Fig. 6.7). 

Run boiler feed water pumps alternately so that all of them are in working... 

It is desirable to have diesel generators sets of sufficient capacity as stand by the soiurce of power with automatic change over faciUly. These shall be used for operating equipment for emergency use such as alkali circulation pumps and induced draught fans for scrubbers, refrigeration units (to prevent escape of volatile solvents), fire hydrant pumps, boiler feed water pumps, and plant lighting. 

Stmctural saddle supports and woik platforms may be obtained from the vendor. Vendor shall supply all standard fittings and valves for feed water, blowdown, vent, safety, as well as steam stop valves, instmmentation, level controllers with low-level alarms, and boiler feed water pumps with motors. All of these shall be supplied with test certificates and approval of statutory authorities. 

It will be seen that passing a large quantity of water through the economiser coils needs considerable power to run the feed water pumps. 

The feed water pump is run intermittently only to maintain the water level in the flash drum (which is a separate unit), corresponding to the amount of water evaporated. Such steaming-type economisers can be seen in a sulphuric acid plant. 

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