Temporary shut-down

Since continuity of the process and safety are prime considerations, plant security will require duplication of all items of apparatus so that a temporary shut-down for repair or maintenance will not reduce the cooling capacity. 

In a plant producing 200 kt/a of ethylene from cracked naphtha, acetylene in the product was hydrogenated to ethylene in a catalytic unit operated under conditions mild enough not to hydrogenate ethylene. During a temporary shut-down and probably owing to operating error, the internal temperature in the catalytic unit rose to... 

An important influence on production cost has, of course, the so-called on-stream factor, the number of production days per year. It is standard practice to assume that a well designed and operated plant should be capable to reach a minimum of 330 days per year, a value on which economic calculations are usually based. Modern plants often achieve higher on-stream factors. A beneficial effect is also that many plants achieve higher capacity than the original design. Plant outages because of operational problems or temporary shut downs for economic reasons because of unfavorable market situation can lower the profitability considerable. The on-stream factor is an average value, because plants should shut down only every 2 to 3 years for a major turn-around for repair and preventive maintenance. Only a very few short unscheduled shut-downs for repair work should occur between two turn-arounds. A start up needs between 15 to 30 hours and consumes a considerable amount of natural gas without an equivalent production (100 000-200 000 DM/d). 

A propane leak at TOCDF caused a temporary shut down of operations. DCD Fire Department was summoned. The fire department set up gas detectors and determined that there was no immediate danger. No agent or munitions involved. 

To identify the main factors of safe work of the advanced melters EP-500/3,4, six years of experience using the melter EP-500/lp are summarized efficiency, technological deviations, and equipment failures, as well as violations of water-cooled system, off-gas system, control and measuring instruments that resulted in the temporary shut down of the vitrification process are studied. 

Air current segregation, which often results in fluctuations in the dust content of the discharged material, can lead to severe downstream problems with equipment depending on fluidisation for their operation, such as air slides and volumetric feeding devices. Investigations carried out in aluminium plants have shown that the consequences of such periodic fluctuations in quality are anode effects and temporary shut down of distribution systems. 

The legs of the platform can be used as settling tanks or temporary storage facilities for crude oil where oil is exported via tankers, or to allow production to continue in the event of a pipeline shut down. The Brent D platform in the North Sea weighs more than 200,000 tonnes and can store over a million barrels of oil. Topside modules are either installed offshore by lift barges, or can be positioned before the platform is floated out. 

Total reflux exists in a distillation column, whether a binary or multicomponent system, when all the overhead vapor from the top tray or stage is condensed and returned to the top tray. Usually a column is brought to equilibrium at total reflux for test or for a temporary plant condition which requires discontinuing feed. Rather than shut down, drain and then re-establish operating conditions later, it is usually more convenient and requires less... 

The northern Canadian Cordillera is one of the most well-endowed (richest) tungsten districts in the world (e.g., Dick Hodgson 1982). The highest grade tungsten deposit in this district is the Cantung mine, a world-class tungsten skarn with recent reserve estimates of 2.9 Mt at 1.21%W03 indicated and 0.73 Mt at 0.74%W03 inferred (Clow et al. 2006), and over 4.6 Mt at 1.6%W03 removed prior to temporary mine shut-down in 2003 (Rasmussen 2004). 

If there is just one point outside the action limits, there should be an immediate evaluation. If there are two points or more in a brief period of time, the system should be shut down and analyzed for the cause. An example is Figure 5.13. As stated there, one possibility is a temporary contamination in the distilled water supply, which is certainly a concern even for a short period of time. A system out of statistical control, even for a short period of time, diminishes the reliability of any results. 

A temporary haven can be a room or building that, because of its design and construction, can provide protection to a few people for the expected duration of a toxic release. Usually control rooms in plants are set up as safe havens for operators, to enable them to effect an orderly and safe shutdown of the facility and isolate the source of the release. These control rooms are usually fitted out with special HVAC systems that can be shut down quickly, air intakes that close tightly, and a separate supply of breathing air capable of supporting the necessary personnel for an extended period of time. 

The first death occurred on the third day and on the fourth day, the number of deaths increased so that a temporary morgue had to be set up. The town s eight physicians were too few in number to attend to all who were affected. All during this period, the plants continued to spew pollution, containing particulates, sulfur dioxide/sulfuric acid, zinc, lead and cadmium, into the air. It was not until the morning of the 30th that the Donora Zinc Works shut down and later that afternoon, rains finally arrived and washed the smog from the air. 

This chapter deals with the discussion of all OPUS data processing and manipulation procedures, which are shown in Fig. 10.1. These functions allow you to transform or analyze the spectral data after it has been acquired. The results of all operations are temporary files, i.e. existing only in the computers memory, called work files that must be saved explicitly. If you exit OPUS without saving the work files to disk, the results of the data manipulation will be lost. OPUS warns you in case you attempt to shut down the program. 

The problem of leaks in gasket joints is common, especially in steam lines, both for conventional and for nuclear plants. It rarely entails shutting down the plant for necessary maintenance. Some temporary solutions adopted by various plants are ... 

Cold start Shut-down strategy importance on freezing of process water on catalyst layer of MEA Results the degree of dryness in the stack significantly influences cold start-up ability, increasing dryness improves performance the optimal shut-down strategy allows start-up from -6 C without any performance loss, lower temperatures will see temporary performance loss Schiebwohl et ai, 2009... 

If an instrument or instrument system malfunctions, the operator tries to correct the problem. If an alarm, flow or temperature measuring instrument or shut down system malfunctions, the operators first response should be an attempt to restore it to service. It may be a plugged impulse line, inadvertent flow shut off to an analyzer, etc. If the Instrument System is a Class I or 2, immediately go to Step 2. If the alarm is a Class 3, the Lead Operator (or Shift Foreman) should be consulted and follow established procedures and his knowledge of the unit and the specifics of the situation to determine the temporary steps required. At the minimum, a note in the maintenance logbook must be made to initiate repairs. Stop Here for Class 3 Alarms. 

Prior to shutting down, erect a temporary platform at the converter manhole from which catalyst will be removed. Provide safe access to the platform. 

COMPLETE PLANT SHUT DOWN COMPLETE SHUT DOWN OF ONE SECTION COMPLETE SHUT DOWN OF A LINE INTERRUPTION OF LINE FOR <8 HRS SHIFT. TEMPORARY INTERRUPTION OF LINE < 4HRS. 

In January 1967, N Reactor was shut down because its plutonium production capability was not needed, but in April 1967 DOE agreed to operate N Reactor solely in a power-production mode for supplying steam to HGP in response to electrical power needs in the Northwest. On June 21, 1967, a fire in the 109-N Steam Generator Building Cell 3 of the reactor resulted in a temporary shutdown. The N Reactor was restarted on July 21 of the same year. 

Answer The xenon builds up after the pile is shut down cbsorling the react vlty forr.erly held by the temporary poison. Thus, in the operating period after poison discharge it is possibi.e to attain turnarc-iund at a high power level. . ith only the horizontal, rod controls, and, ohoroforo, nerr.it a rapid rise to the ccrailibriam power level. 

Hun (or Poison Run) A short period (few hours) of operation of a reactor after a sxarTi-up with ter.porary poison charged in the active zone. After the reactivity has reached a maximuni and is decreasing the reactor is shut down so the temporary poison can be discharged. 

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