On-stream factor

The heart of an electrolysis plant is its electrolysers. The factors that improve the Rol are features such as low energy consumption and high on-stream factors, flexibility of plant load, high current densities and short electrolyser downtime periods for maintenance. 

All these modifications lead to the fulfilment of all aspects for an improvement of the Rol by KU single element technology and high efficiency of the latest cell design, such as low energy consumption with a high on-stream factor for the plant, simple and rapid maintenance of the electrolysers, plant load flexibility and high current densities. 

This would account for a typical 3-4 week turnaround period with the remaining days representing unplanned feed outages. Extending the turnaround interval to 5 years with an improved on-stream factor of about 0.98 is a reasonable target for refiners. 

Economic analysis of costs based on pilot-scale demonstration results gave an estimated cost of 98 to 206 per ton of waste treated. 85 to 90% of these costs are for raw materials (cement and Chloranan) and labor. The lowest value ( 98 per ton) is based upon the vendor s expectation of reducing chemical consumption by 33%, attaining an on-stream factor of 90%, and using a new 2300-lb/min batch processing unit. These costs do not include profits of the... 

Eighty percent on-stream factor at 292 days per year. 

To determine the required selling price of hydrogen, a cash flow analysis was performed using an after-tax internal rate of return (IRR) of 15%. Other major assumptions used in the analysis were equity financing for a 20 year plant life including two years of construction time, a 90% on-stream factor with 50% plant capacity in first year of production, 30% of capital investment is spent in the first year and 70% in the second year, a tax rate of 37%, and ten year straight-line depreciation. 

Dihydrate process maintenance costs are substantially less than those for hemi processes due to less severe process conditions. The on-stream factor is also higher for the average dihydrate facility. 

The plant operates 330 days/yr (90 percent on-stream factor). 

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). 

If the predicted corrosion rate indicates only short exposures, then the design engineer should allow for frequent inspection of the plant and periodic replacement of the affected equipment. This affects process economics in two ways, as it reduces the on-stream factor (number of days of production per year) and increases the maintenance costs. Usually the economic impact of frequent shutdown and replacement is so negative that use of a more expensive alloy with better corrosion resistance can be justified. 

As was expected, demetallation/denitrification of the feed stock was substantially lower than that for Catalyst Systems B and C. Even though product pattern with this system was superior, short catalyst cycle length and consequently limited On-Stream Factor (OSF) weighed heavily against it. Short catalyst cycle length was operationally uneconomical due to frequent shut downs. 

The technologies for production of syngas from hydrocarbons are based on either steam-reforming or partial oxidation. In the former case, the hydrocarbons react with steam with considerable addition of heat to produce a syngas with a H2/CO ratio of 3 or more. Partial oxidation may be carried out either thermally or catalytically (or by a combination) to produce a syngas with an H2/CO ratio less than 2. Regardless of technology, CO2 may be added to the feed to adjust the gas composition to a low H2/CO ratio. In all cases, limits for the formation of carbon on catalysts or soot in the condensate must be considered to avoid rapid deactivation and low on-stream factors. 

Reliability and on stream factor Average Average Expected above average/high... 

In comparison with other oxo processes the procedure is much simpler and many steps in the original process are superfluous (cf. Section 5) [57]. The actual oxo catalyst is simply made within the oxo unit by reacting suitable Rh salts with TPPTS of appropriate quality without any additional preformation step. The reaction system is self-adjusting the on-stream factor of the whole system is > 98%. Typical reaction conditions and performances on a 14-year average are given in [56, 57]. 

It takes into account the on-stream factors that can cause unscheduled shutdowns. It is an important project consideration, particularly if the process is a primary source of makeup hydrogen to a hydro processor or other mainstream refinery processes. 

Membrane systems are extremely reliable with respect to the on-stream factor. The membrane separation process is continuous and has few control components that can cause a shutdown. Typically, the response to unscheduled shutdowns is rapid. 

Reliability takes into account the on-stream factors which can cause unscheduled shut-downs. Membrane systems are extremely reliable with respect to the on-stream factor. The membrane separation process is continuous and few control components can cause a shut-down. Typically, the response to unscheduled shut-downs is rapid for GS whereas PSA systems are moderately reliable owing to the numerous valves associated with the process which can cause unexpected shut-downs. The new PSA are designed with alternative modes of operation, in which 100% of design capacity can be achieved while by-passing any failed valve or instrument, with only a slight recovery loss. Failures are automatically detected and by-passed by the microprocessor-based control system. Flowever, stronger and periodic control cycles are required. The cryogenic process is considered by refiners to be less reliable than PSA or membrane... 

This is especially true during the startup and the first 3-4 years of operation when the on-stream factor (40%-50% denoted for large-scale plants) has a consequent disastrous effect upon revenue, earnings, and profitability. 

With hydroprocessing units, most refiners try to maximize feed rate while (a) meeting other process objectives and (b) maintaining a high on-stream factor. Some try to maximize conversion, while others just want to hit a key process target at minimum cost. 

High residue conversion levels up to 95 wt%, and an on-stream factor of around 87% with high quality products have been reported [Trimm et al, 1990]. A special additive is used in the CANMET process to suppress coke formation and obtain higher conversion. 

On-Stream factor 350 days per year (continuous operation)... 

Plant complexity for the process may result in on-stream factors less than those typically ejqiected for the steam reforming process. 

However, the following apply generally. Steam reforming of natural gas will undoubtedly continue as the process of choice for most new methanol installations. Energy efficiency for this route is competitive the reliability is such that on-stream factors of well over 90% are possible, and the capital cost will generally be the most attractive of all potential alternatives. Single-train capabilities of up to 3000 tpd are possible with this proven technology. 

Me Namara, D.J., Sherwood, D.E., Ginestra, J.M., Ijistra, W.D. 2007. Correct catalyst selection leads to improved on-stream factor in high conversion resid upgrading units. In Second Russia CIS Bottom of the Barrel Technology Conference and Exhibition, Marriot Grand Hotel, Moscow, 18—19 April. 

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