Load Schedules

The load schedule specifies for normal at-power operation a unique plant steady state at each power level over the normal operating range, typically from 25 to 100% of full power. This includes the values of all plant forcing functions such as turbo-machine power inputs and reactor and cooler heat rates. For normal operating transients the load schedule gives conditions at which a transient begins and ends. If the transient is an upset event, then while it begins from a point on the load schedule it may terminate at some stable off-normal condition not found on the load schedule. 

In the PCU during rapid transients the rate at which inventory must be changed according to the load schedule may not be physically achievable. The helium fill and bleed system has limited capacity. In this case turbine bypass control is used to more quickly vary the power output of the shaft. In this scheme the power output of the turbine is changed by bypassing high pressure compressor outlet coolant to the exit of the turbine. The pressure drop across the turbine is reduced so power is reduced while at the same time the frictional losses through the rest of the PCU circuit increase. The result is a rapid reduction in shaft power. However, PCU efficiency is reduced under turbine bypass control and so control is typically transitioned back to inventory control over time. 

The values of plant process variables for steady-state hydrogen production rates between 75 and 100% of full power are given by the load schedule reported here. The objective in designing this schedule was to achieve near constant hot side temperatures in both the nuclear and chemical plants. Briefly, mass flow rates are maintained proportional to power throughout, inventory control is used in the PCU, and electrolytic cell area and current are maintained proportional to hydrogen production rate. 

Figure 4 Load schedule for reference interface - HTE temperatures...

The performance of the reference interface is characterised in Vilim (2007). In that work the GPASS/H code was used to determine the full power condition, the combined plant efficiency and the partial power load schedule. The values of the main operating parameters are summarised in Table 1. 

Partial power operation takes place over a continuum and is constrained by the load schedule. The load schedule specifies the value of each process variable as a function of plant power. Good operability as characterised by minimal thermal stresses during power change is achieved by developing a load schedule that maintains temperatures constant with respect to load at the hottest points in the plant (e.g. reactor outlet). 

The load schedule performance is assessed in terms of how well temperatures on the hot side of the combined plant are maintained constant. Also of interest are the pressures on the helium side for assessment of creep under pressure load. The pressures in the HTSE plant were maintained at 5 MPa over the load schedule from the point downstream of where the reactant water is fed in up to the point where the products enter the pressure-work recovery turbine. 

Operational Procedures operator commands, override control, process monitoring, parameter modification, load scheduling, startup and shutdown, fault-finding instructions, user manuals and documentation... 

Load schedule, power factor correction scheme, relay coordination study and diagram. 

Correction The Construction Manager must insist that every subcontractor submit its own labor-loaded schedule and check them for compatibility with each other and with the master project schedule. 

Based on a limited amount of test data, it appears that the units may not be able to meet specific local air pollution codes. Particulate stack plumes are visible, especially when operation requires an accelerated loading schedule to lower primary combustion temperatures. 

Silicate grouts, depending upon grout and catalyst concentrations, may take from several days to as much as 4 weeks to reach maximum strength. Creep studies should be correlated to specific field loading schedules in order to give realistic results. 

At this stage the engineer can begin to prepare a load schedule for each subsidiary switchboard and motor control centre, and a master schedule for the main switchboard. The development of the single-line diagrams during the project is discussed in sub-section 1.7. 

The above method can be used very effectively for estimating power requirements at the beginning of a new project, when the details of equipment are not known until the manufacturers can offer adequate quotations. Later in a project the details of efficiency, power factor, absorbed power, rated current etc. become well known from the purchase order documentation. A more accurate form of load schedule can then be justified. However, the total power to be supplied will be very similar when both methods are compared. 

Table 1.5. Subsidiary load schedule for the low voltage process switchboard...

Table 1.8. Master load schedule for the high voltage main switchboard...

During the detail design phase of the project the load schedules will be modified and additional loads will inevitably be added. At least 10% extra load should be added to the first estimate i.e. 1203 kW. The total when rounded-up to the nearest 100 kW would be 13,300 kW. 

The development of a detailed construction schedule is necessary for the coordination of the various contractors and monitoring the progress of the construction. A resource-loaded schedule for construction activities is necessary. Labor requirements must be evaluated from both availability and the density within the construction project. A general rule of thumb is to plan on one construction worker for every 200 gross square feet of building. In the case of compact process facilities, this can require spot density of one worker... 

Marshall, 1994) Marshall, P and Silver, R. Sizewell B Computer Controversy Looms Over Fuel Load Schedule, jVMc/eow/cs Week, 34, pi. 1994... 

A resource-loaded schedule, including resource constraints Other constraints such as financial, political, regulatory, and logistics Start and end dates for the project... 

The electrical conditions of cell operation are determined by the load schedule. Typically, primary batteries are used with complicated, and often arbitrary, loading schedules. The current drain of a transistor radio battery, for example, is a function of the volume setting the times of turning the set on and off are arbitrary. Batteries in electronic watches and pacemakers are loaded continuously but the discharge current is pulsed. The cases of continuous discharge to a constant load are rather infrequent. 

Embankment height (m) Traffic load distribution at cap level (kN/m ) Pile distance, in square pattern based on load schedule (m)... 

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