Normal Startup Research Articles

Experimental study on fluidized-bed start-up process with hot gas

For simulating the Pressurized Fluidized Bed Combustion (PFBC) start-up with high-temperature oil-fired gas, systematical experimental study and theoretical analyses were carried out on an Atmospheric Fluidized Bed Combustion (AFBC) test facility which has a water-cooled distributor in cross-section of 0·664 m×0·656 m. The characteristics of heat transfer of the water-cooled distributor were revealed. The effects of some operating parameters on the normal start-up process are evaluated. The findings reported in this paper are used to provide a data base for designing PFBCB start-up systems. It can also be applied to the design of AFBC boilers and the improvement of existing ones. © 1998 John Wiley & Sons, Ltd.

Real time generation of operating procedures to support flexible start-up operation

Start-up operating procedures are usually generated in advance which may not be flexible when facing different initial operating conditions. This is especially true when meeting abnormal situations during operation. In such cases, the existing procedures must be revised based on the current status of the plant. To improve this, a method for normal start-up operation which generates operating procedure on the fly by using the current status of the plant is presented here. Such a method has been implemented into a real time support system called PRETISS. Several experiments has been carried out to prove the effectiveness of the method and the support system.

A Quasi-Steady Performance Prediction Model for Dynamic Characteristics of a Volute Pump

A performance prediction model generally applicable for volute-type centrifugal pumps has been extended to predict the dynamic characteristics of a pump during its normal starting and stopping periods. Experiments have been conducted on a volute pump with different valve openings to study the dynamic behaviour of the pump during normal start-up and stopping, when a small length of discharge pipeline is connected to the discharge flange of the pump. Such experiments have also been conducted when the test pump was part of a hydraulic system, an experimental rig, where it is pumping against three similar pumps, known as supply pumps, connected in series, with the supply pumps kept idle or running. Instantaneous rotational speed, flowrate, and delivery and suction pressures of the pump were recorded and it was observed in all the tested cases that the change of pump behaviour during the transient period was quasi-steady, which validates the quasi-steady approach presented in this paper. The nature of variation of parameters during the transients has been discussed. The model-predicted dynamic head-capacity curves agree well with the experimental data for almost all the tested cases.

A project milestone bonus plan: Bringing a plant startup on‐line, on time, on cost

AbstractStarting up a major appliance plant is an enormously complex task involving thousands of projects at numerous locations, all coming together to attain an on‐cost production plan. This task is tough enough to manage when the plant is a greenfield startup in the United States. It is several magnitudes more complex when it is undertaken by a US. company in central Mexico in a new joint venture with a Mexican partner.In such a recent joint‐venture greenfield startup, a major appliance manufacturer went from concept to full production in less than half the normal startup time. According to this case study, giving the technical team bonus incentives helped build the commitment necessary to achieve success.

The Effect of BWR Startup Environments on Crack Growth in Structural Alloys

During startup of a Boiling Water Reactor (BWR), the water chemistry and temperature are constantly changing. Special operational practices can be performed to control the dissolved oxygen level using, for example, vacuum deaeration. To assess the impact of startup practice on environmental cracking in the structural materials used in the BWR, a large program was performed to evaluate crack growth at representative environmental conditions for both conventional and vacuum deaeration startup practices. Five alloys were studied: Types 304 and 316 nuclear grade stainless steel, Inconel 600, carbon steel, and A508-2 low alloy steel. Tests were performed using fracture mechanics type specimens with constant load crack growth measured at appropriate stress intensity levels. The program intent was to compare the crack growth rates for the two practices. The results show that normal startup and startup deaeration environments had varied effects. Sensitized Type 304 stainless steel exhibited a decrease in crack growth rate and concomitant decrease in severity of intergranular fracture morphology at the low temperatures under deaeration. In contrast, the Type 316 nuclear grade displayed very little influence of startup deaeration due to its inherent resistance to stress corrosion cracking. Inconel 600 showed up to a factor of five reduction in crack growth rate in the deaeration environment. The response of the carbon steel to deaeration was mixed—limited benefit was seen at low temperature, none was seen at the higher temperature. Finally, the low alloy steel displayed some improvement in behavior at low temperature at the high stress intensity value investigated. In summary, the program showed that a modest benefit, in terms of stress corrosion cracking mitigation, could be attributed to deaeration during startup, particulary for Type 304 stainless steel and Inconel 600.

Start-Up Pressures in Short Pump Discharge Lines

Critical transient pressures may occur during normal start-up in pump discharge lines not provided with control valves. Requirements for the computation of these transient pressures are described and a method of analysis is presented in the form of an example problem. The special terms, total start-up time, short pipeline and potential start-up head are defined and analyzed. Alternative methods of calculating or estimating the time for pump to reach rated speed are described. Differences in pressures for short and long pipelines are reviewed.

Operation and Performance of Modern Reheat Boilers

Abstract This paper illustrates typical designs of reheat boilers and discusses operating procedures for normal start-up, quick start-up, normal operation, and shutdown under normal or emergency conditions.