Pumps boiler feed

Fig. 25. Schematic of large fossil steam turbine system where BFPT = boiler feed pump turbine. To convert MPa to psi, multiply by 145.

Thermal power plant auxiliaries such as flow control of primary air fan, ID fan and forced-draught fans, boiler feed pumps circulating water pumps and condensate pumps, coal handling plant (e.g. ball mill, wagon tippler, and stacker reclaimer)... 

These applications have considerably more stringent performance requirements than any other application. Circulating water pumps, boiler feed pumps, forced-draught (FD) and induced-draught (ID) fans, pulverizers (ball mills) and condensate pumps are components in a thermal power station that may require extra safety in a standard motor to make it able to fulfil these requirements and withstand abnormal service conditions and system disturbances. Abnormal operating conditions may be one or more of the following ... 

Power house auxiliaries ID fans, FD fans, primary and secondary air fans, boiler feed pumps and slurry... 

Makay, E., How to. Avoid Field Problems With Boiler Feed Pumps, Hydrocarbon. Processing, V. 55, No. 12, 1976. 

The efficiency of the cycle, ignoring work done by the boiler feed pumps, is given by change in enthalpy as follows ... 

Large power stations use complex feed heating systems before the boiler feed pumps (LP) and after the boiler feed pumps (HP), which can give high overall thermal efficiencies of 39 per cent. However, for the smaller machine, it becomes uneconomic to consider multiple bleeds from the turbine, and the final choice is dictated by the extra cost for the additional complexity against lower running costs due to increased efficiency. As a minimum, a contact type de-aerator is often employed which would extract a small bleed of around 2-3bar from the turbine. 

Typical pump cross-sections are shown in Figures 32.7-32.10. Figure 32.11 illustrates a multi-stage design where identical stages are assembled in a pressure casing as in a boiler feed pump. 

Feed points for AVT treatments vary, usually hydrazine is added to the base of the deaerator but it also can be added to the base of the condensate extraction pump. Ammonia (where used) or amine is injected into the suction side of the boiler feed pump. 

Selection of Boiler Feed Pumps, Bulletin 781.1, Goulds Pumps, Inc. Seneca Falls, N.Y., Jan. 31, 1968. 

Steam condensate at 1 atm and 95°C (Pv = 526 mmHg) is returned to a boiler from the condenser by a centrifugal boiler feed pump. The flow rate is 100 gpm through a 2.5 in. sch 40 pipe. If the equivalent length of the pipe between the condenser and the pump is 50 ft, and the pump has an NPSH of 6 ft, what is the maximum height above the condenser that the pump can be located ... 

Boeing Rocketdyne, corporate decision making by, 24 386 Boggsite (BOG), 16 813 Boghead coal, 6 705 Bohr, Niels, 21 289 Bohr frequency, 23 128 Bohrium (Bh), l 492t Boiler deposits, in industrial water treatment, 26 131 Boiler economizers, 10 146 Boiler feed pumps, 21 56 Boilers, 10 152 23 215-216... 

Recommendations also are made by the Hydraulic Institute of suction specific speeds for multistage boiler feed pumps, with S = 7900 for single suction and 5 = 6660 for double suction. Thus the required NPSH can be found by rearrangement of Eq. (7.14) as... 

Two of the units at the Oak Creek Power Plant have full-sized steam turbine driven boiler feed pumps, along with half-sized motor driven boiler feed pumps for use at low loads and unit startup. The boiler feed pump turbines are supplied with steam from a particular turbine "bleed-point". 

Turbine bleeder pressure is roughly proportional to unit load at less than one half unit load, the bleeder pressure becomes too low to power the boiler feed pump turbines. Therefore, either the motor driven boiler feed must be employed, or a "booster" supply must be used to provide steam to the boiler feed pump turbine using steam which is throttled from a higher pressure. 

Figure 11. Cost of driving the boiler feed pump with alternate energy sources.

Gaggioli, R.A. and Fehring, T., "Economics of Boiler Feed Pump Drive Alternatives", Combustion, 49, 9 (1978), 35-39. 

Cost of package boiler plants. Price includes complete boiler, feed-water deaerator, boiler feed pumps, chemical injection system, stack, and shop assembly labor. 

Related Calculations. Use this procedure for any condensate or boiler-feed pump handling water at an elevated temperature. Consult the Standards of the Hydraulic Institute for capacity curves of... 

Centrifugal boiler-feed pumps usually have a maximum allowable temperature rise of 15°F. The minimum allowable flow through the pump to prevent the water temperature from rising more than 15°F is 30 gal/min for each 100 bhp input at shutoff. 

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