Periodic


Solution We wish to avoid as much as possible the production of di- and triethanolamine, which are formed by series reactions with respect to monoethanolamine. In a continuous well-mixed reactor, part of the monoethanolamine formed in the primary reaction could stay for extended periods, thus increasing its chances of being converted to di- and triethanolamine. The ideal batch or plug-flow arrangement is preferred, to carefully control the residence time in the reactor.  [c.50]

Rather than use a cloth, a granular medium consisting of layers of particulate solids on a support grid can be used. Downward fiow of the mixture causes the solid particles to be captured within the medium. Such deep-bed filters are used to remove small quantities of solids from large quantities of liquids. To release the solid particles captured within the bed, the flow is periodically reversed, causing the bed to expand and release the particles which have been captured. Around 3 percent of the throughput is needed for this backwashing.  [c.74]

Find a way to overcome the constraint while still maintaining the areas. This is often possible by using indirect heat transfer between the two areas. The simplest option is via the existing utility system. For example, rather than have a direct match between two streams, one can perhaps generate steam to be fed into the steam mains and the other use steam from the same mains. The utility system then acts as a buffer between the two areas. Another possibility might be to use a heat transfer medium such as a hot oil which circulates between the two streams being matched. To maintain operational independence, a standby heater and cooler supplied by utilities is needed in the hot oil circuit such that if either area is not operational, utilities could substitute heat recovery for short periods.  [c.184]

Short-term exposure. This is the maximum concentration to which workers can be exposed for a period of up to 15 minutes continuously without suffering from (a) intolerable irritation, (b) chronic or irreversible tissue change, or (c) narcosis of sufficient degree to increase accident proneness, impair self-rescue, or materially reduce efficiency, provided that no more than four excursions per day are permitted, with at least 60 minutes between exposure periods, and provided the daily time-weighted value is not exceeded.  [c.260]

The effects of pollution can be direct, such as toxic emissions providing a fatal dose of toxicant to fish, animal life, and even human beings. The effects also can be indirect. Toxic materials which are nonbiodegradable, such as waste from the manufacture of insecticides and pesticides, if released to the environment, are absorbed by bacteria and enter the food chain. These compounds can remain in the environment for long periods of time, slowly being concentrated at each stage in the food chain until ultimately they prove fatal, generally to predators at the top of the food chain such as fish or birds.  [c.273]

Na Mg Al Si P S Cl across each row of the periodic table and de-  [c.151]

The definitive reference series in inorganic chemistry although the complete periodic table is not covered.  [c.194]

Y is in a higher group in the periodic table than X  [c.200]

Prepared by use of HjOj or by electrolytic oxidation. Persulphuric acids, perborates, are of importance. (Permanganates, perchlorates and periodates are not salts of per-acids.) Organic per-acids are prepared similarly. The  [c.299]

Each country adopts such and such a class as a function of its climatic conditions. France has chosen classes B, E, and F, respectively for the summer, winter, and cold wave periods. The first is from 1 May to 31 October, the second is from 1 November to 30 April, while the third has  [c.215]

To lessen the risk of pumping sludges or slurries into a unit, the practice is to leave a safety margin of 50 cm (heel) below the outlet nozzle or install a strainer on the pump suction line. The deposits accumulate with time and the tanks are periodically emptied and cleaned.  [c.327]

Drill ships are used in deep water and remote areas, and these vessels are equipped with a drilling unit positioned in the middle of the ship. Positioning is achieved dynamically by computer controlled thrusters. The ample storage space allows operation for long periods of time without re-supply.  [c.34]

This kind of pressure solution / precipitation is active over prolonged periods of time and may almost totally destroy the original porosity. Precipitation of material may also occur in a similar way on the surface of fault planes thus creating an effective seal via a process introduced earlier as diagenetic healing.  [c.87]

This rather low recovery factor may be boosted by implementing secondary recovery techniques, particularly water Injection, or gas injection, with the aim of maintaining reservoir pressure and prolonging both plateau and decline periods. The decision to implement these techniques (only one of which would be selected) Is both technical and economic. Technical considerations would be the external supply of gas, and the  [c.188]

If high wellhead pressures are available over long periods, cooling can be achieved by expanding gas through a valve, a process known as Joule Thomson (JT) throttling. The valve is normally used in combination with a liquid gas separator and a heat exchanger, and inhibition measures must be taken to avoid hydrate formation. The whole process is often termed low temperature separation (LTS).  [c.251]

Servicing of items is a routinely scheduled activity which is managed in the same way as inspection, and the periods between services will depend on the design of fhe equipment. The periods may be set on a calendar basis (e.g. every 24 months) or on a service hours basis (e.g. every 10,000 operating hours).  [c.343]

The oil company will also be required to periodically submit reports to the national oil company (NOG) or government, and to partners in the venture. These typically include  [c.346]

There is no single solution to the organisational structure required to achieve this objective, and companies periodically change their organisation to try to improve efficiency. The above list shows information required for daily operations, and a quite different list would be drawn up for development planning. Often the tasks required for production and development are split up, and this is reflected in the organisation. The following structure is one example of just part of a company s organisation.  [c.348]

One of the important reasons for internal reporting is to provide a data base of the activities which can be analysed to determine whether improvements can be made. Although the process of reviewing progress and implementing improvements should be ongoing, there will be periodic audits of particular areas of the company s business. Audits are often targeted at areas of concern and provide the mechanism for a critical review of the process used to perform business. This is simply part of the cycle of learning, which is one of the basic principles of management  [c.349]

The funding of the activities of the company is managed by the finance department, but the spending of the funds is managed by the technical managers. The budget reports are the mechanism by which the manager keeps track of how the actual revenue and expenditure is performing against the plan as laid out in the budget. The budget will be planned on an annual basis, split into 3-month periods, and will be updated each quarter.  [c.349]

The planning of decommissioning activities involves extensive periods of consultations with the relevant authorities and interested parties, such as fishing and environmental groups.  [c.366]

Operating strategies and product quality should be carefully reassessed to determine whether less treatment and more downtime can be accommodated and what cost saving this could make. Many facilities are constructed with high levels of built-in redundancy to minimise production deferment early in the project life. Living with periodic shutdowns may prove to be more cost effective in decline. Intermittent production may also reduce treatment costs by using gravity segregation in the reservoir to reduce water cuts or gas influx, as mentioned in Section 15.4.  [c.367]

The utilization of high strength bolts in the construction of bridges has spread during the past 20-25 years. Official regulations concerned with checking the state of bridges require periodic examination of the condition of these bolts as well. Such examinations - in accordance with the relevant DIN standard - are based on the correlation between the degrees of further swivelling of the nut and the applied torque Based on experience the following objections can be raised against this method  [c.3]

CH2CI-CO-CH3. Colourless lachrymatory liquid b.p. 119°C. Manufactured by treating propanone with bleaching powder or chlorine. It is used as a tear gas and is usually mixed with the more potent bromoacetone. chloro acids Complex chloroanions are formed by most elements of the periodic table by solution of oxides or chlorides in concentrated hydrochloric acid. Potassium salts are precipitated from solution when potassium chloride is added to a solution of the chloro acid, the free acids are generally unstable.  [c.93]

The modern lubricant is a highly technicological product containing 15 to 20 weight per cent of various additives that enable the engine to function under increasingly severe conditions. For example, the reduction in the automobile Cx coefficient (which lowers the engine cooling capacity) and the longer oil-change interval both of which are sought by the owner, force the lubricant to operate at higher temperatures and for longer periods of time.  [c.354]

Tender Assisted Drilling. In some cases oil and gas fields are developed from a number of platforms. Some platforms will accommodate production and processing facilities as well as living quarters. Alternatively these functions may be performed on separate platforms, typically in shallow and calm water. On all offshore structures however, the installation of additional weight or spaoe is costly. Drilling is only carried out during short periods of time if eompared to the overall field life span and it is desirable to have a rig installed only when needed. This is the concept of tender assisted drilling operations. A derrick is assembled from a number of segments transported to the platform by a barge. All the supporting functions such as storage, mud tanks and living quarters are located on the tender, which is a specially built spacious barge anchored alongside. It is thus possible to service a whole field or even several fields using only one or two tender assisted derrick sets. In rough weather, barge type tenders quickly become inoperable  [c.34]

Alkanes from CH to C4gFlg2 typically appear in crude oil, and represent up to 20% of the oil by volume. The alkanes are largely chemically inert (hence the name paraffins, meaning little affinity), owing to the fact that the carbon bonds are fully saturated and therefore cannot be broken to form new bonds with other atoms. This probably explains why they remain unchanged over long periods of geological time, despite their exposure to elevated temperatures and pressures.  [c.91]

PSCs are agreed with a schedule for exploration, appraisal and development, and production periods. During these times the terms of the PSC are usually fixed, thus reducing some of the uncertainties associated with tax and royalty systems where the royalty and tax rates may vary over the field lifetime.  [c.316]

An equipment item is designed to certain operating standards and conditions, beyond which it should not be operated. To ensure that the equipment is capable of performing safely at the design limit conditions, it must be periodically /nspectedand/or tested. For example, a water deluge system for fire-fighting would be periodically tested to ensure that it starts when given the appropriate signal, and delivers water at the designed rate. If equipment items have to be shut down to test or inspect them (e.g. inspecting for corrosion on the inside of a pressure vessel) this will make the equipment temporarily unavailable. If the equipment item is a main process system item, such as one of those shown in Figure 14.9, then the complete production train would be shut down. This would also be the case in testing a system that was designed to shut down the process in the case of an emergency. This causes a loss of production. Where possible, inspection and testing is designed to be performed on-line to avoid interrupting production, but otherwise such inspections are scheduled to coincide. The periods between full function testing of process equipment is sometimes set by legislation.  [c.343]


See pages that mention the term Periodic : [c.116]    [c.166]    [c.304]    [c.315]    [c.334]    [c.45]    [c.55]    [c.63]    [c.80]    [c.196]    [c.218]    [c.285]    [c.300]    [c.300]    [c.300]    [c.300]    [c.300]    [c.300]    [c.325]    [c.365]    [c.402]    [c.189]   
Gas turbine engineering handbook (2002) -- [ c.0 ]