Auxiliary feed lines

Two medium-voltage buses supplied from the secondary windings of the two transformers on the Class IV primary medium-voltage buses, which supply power to the pumps in the service water system, ECCS, moderator circulation system, shutdown cooling system, HTS feed lines, steam generator auxiliary feed line, and the air compressors and chillers. 

Auxiliaries are additional boiler fittings that provide controls for ease of operation. They may include additional valves (such as check valves on feed lines, nonreturn valves on steam distribution lines, and the various boiler system drain valves), gauges, connections, and devices to regulate FW, air, and fuel and to provide for the efficient production, pressure, temperature, quality, and flow of HTHW or steam. 

The compressed oxidant can be added to the feed prior to reaching the reactor or added directly to the reactor through a separate feed line. Similarly, several other supplemental feed streams may be added to the organic feed at any point or fed separately to the reactor. These other feeds are typically added to allow for better control of conditions in the reactor. Examples include auxiliary fuel such as kerosene (to maintain reactor temperature for a low-heating-value waste), diluent water (to maintain reactor temperature for a high-heating-value waste), and base (to neutralize acids formed during oxidation). 

T is the transient of main feed-water loss due to loss of electric power supply. M, B indicate the lack of recovery of the outside lines and the non-operation of the station diesels for at least three hours (in the Rasmussen report, the probability of non-recovery of the outside lines in one hour is assumed equal to 2x 10" and the probability, to be combined with the preceding one, of nonrecovery for the other two hours of the same lines, is assumed equal to 5 x 10 ). L indicates the malfunction of the auxiliary feed-water system and therefore also of the turbine-driven pump. 

Again at Davis Besse, on 9 June 1985, a complete loss of normal and auxiliary feed-water occurred. During that event, some motor-operated valves provided with torque limiters in the auxiliary feed-water line could not be re-opened after having been inadvertently closed. It was determined afterwards that the bypass circuit of the torque switch had not been set to stay closed for a time sufficient to allow the opening of the valve in conditions of high differential pressure. 

Main feedwater is supplied to each of the two steam generators through its own main feedwater line. Each of the two lines is anchored at the interface between the auxiliary building and the turbine building, and has sufficient flexibility to provide for relative movement of its associated steam generators resulting from thermal expansion. Each main feed line contains a control valve, a non-return and an isolation valve. These valves are installed in the line before it enters the containment. The main feed lines are a closed system inside the reactor containment, and so they do not require any further valves in the line inside the containment. This is because any radioactivity within the contaimnent atmosphere has no way of passing into a closed system. 

In addition to the formation of scale or corrosion of metal within boilers, auxiliary equipment is also susceptible to similar damage. Attempts to prevent scale formation within a boiler can lead to makeup line deposits if the treatment chemicals are improperly ehosen. Thus, the addition of normal phosphates to an unsoftened feed water ean eause a dangerous eondition by elogging the makeup line with preeipitated calcium phosphate. Deposits in the form of calcium or magnesium stearate deposits, otherwise known as "bathtub ring" can be readily seen, and are caused by the eombination of ealcium or magnesium with negative ions of soap stearates. 

The basic fluid-bed unit consists of a refractory-lined vessel, a perforated plate that supports a bed of granular material and distributes air, a section above the fluid bed referred to as freeboard, an air blower to move air through the unit, a cyclone to remove all but the smallest particulates and return them to the fluid bed, an air preheater for thermal economy, an auxiliary heater for start-up, and a system to move and distribute the feed in the bed. Air is distributed across the cross section of the bed by a distributor to fluidize the granular solids. Over a proper range of airflow velocities, usually 0.8-3.0 m/s, the solids become suspended in the air and move freely through the bed. 

Feed systems utilizing gravity are rarely used. Line pressure is usually adequate for small systems. Auxiliary pumps are required in laiger systems to assure proper flow through all units and to avoid uneven flow should line pressure decrease as other demands for water or the process stream occur elsewhere in the facility. 

The extrusion line includes substrate feed equipment, an extruder, a die, a chill-roll assembly, slitters, a wind-up system, and auxiliary equip-... 

The power supplies to the FW pumps are utiliang static converter units which eliminate the large inrush currents at direct-on-line starting and therefore reduces the requirements on voltage stability (or rather short circuit strength) of the auxiliary power supply system busbars. Feedwater flow control is achieved by adjusting feed pump speed and the feedwater flow control valves. 

An alternative control structure would be to use a Total Q controller. In this scheme the heat transfer in the condenser/reboiler and the heat input in the auxiliary reboiler are added together and become the process variable signal to a Total Q controller. The setpoint of this controller is the output signal of the TCI temperature controller. The output signal of the Total Q controller goes to the control valve in the steam line feeding the auxiliary reboiler. 

The preboiler system is defined here to include feed water pumps and lines, and auxiliary equipment through which the feed water is pumped prior to actually reaching the boiler. If not restricted, one could include a vast variety of units in which the makeup water is conditioned, but which in themselves are not essentially a part of the holier system. This definition then includes such equipment as stage heaters and economizers. 

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