High Plant Availability Research Articles

Performance evaluation of SWCC SWRO plants

The study deals with the performance evaluation of three SWCC SWRO plants, two supplying water to remote area towns and the third supplying water to Jeddah: • the 4400 m 3/d Umm Lujj Plant, commissioned July 1986, • the 2275 m 3/d Al-Brik Plant, commissioned Dec 1983 and • the 12000 m 3/d Jeddah Plant, commissioned 1979. No membrane replacement took place in any of the three plants. In spite of this, the three plants show only a modest annual decline (from design) in productivity ranging from 2.5% at Jeddah plant to 3.5% at Umm Lujj, and 7.17% at Al-Birk plant. The larger decline at Al-Birk plant is possible due to biological fouling of membrane. Product water quality at Umm Lujj and Al-Birk with TDS less than 250 ppm, is within WHO recommended standard of 500 ppm. Salt rejection by both stages of 99.5% at both Umm Lujj and Al-Birk plants indicates that their membranes did not suffer any serious structural damage. The decline in salt rejection at both plants is less than 0.2% per year. On the other hand there has been a decline in salt rejection in Jeddah plant, indicating structural damage to the membrane over the last 10 years. Both Umm Lujj and Jeddah plant had high plant availability, over 95% but their water recovery was modest 24 – 28%. Biological fouling was a problem with the Al-Birk plant in which the feed was chlorinated (4 ppm) & dechlorinated while no biological fouling was reported for the other two plants in which the feed was disinfected by (0.5 – 1 ppm) CuSO 4. Other problems encountered were material corrosion especially with SS 316 and SS 316L in both pretreatment and desalination parts of Jeddah plant.

Modultechnik — Zielsetzung, Aufbau, Konsequenzen und Erprobung

AbstractModular technique: objectives, layout, test facility. In spent fuel reprocessing plants the hot process cells cannot be entered by the personnel without intensive decontamination of the cells and the equipment. In the German reprocessing plant the FEMO technique (i. e. remote handling modular design) is used to achieve high plant availability and to reduce the radiation burden of the personal. The characteristics of the FEMO technique are two canyon cells in which the process equipment is installed in standardized racks arranged on both sides of each cell. The unit of process equipment and rack is designated as the module. This article reports the objectives of the modular technique, the resulting layout, and the test facility program to confirm this maintenance concept.

Desalting - prospects for improvement in technology and reduction in costs

Desalting can already be considered as a reliable means of water production or water quality improvement. At the beginning of this decade, more than 2000 land-based desalting units having a combined capacity of more than 7 million cubic meters per day were operating or under construction. Many of these plants were reported to be operating reliably, demonstrating high plant availability factors. However, in most cases, the desalted water costs are still to high, especially for use in agriculture. In the past decade, desalting cost (in prevailing prices) increased, in some cases very drastically, despite improvement in technology. The main reasons for this were, obviously, the steep increase in energy costs and high rate of overall price inflation. In some cases, however, the cost of desalting was not increased in real prices, especially when using processes having relatively low specific energy consumptions. Desalting of brackish water even decreased in real prices due to impressive improvement in membrane processes, mainly reverse osmosis. For seawater desalting, recent developments and especially those now under development related to reverse osmosis membranes and efficient power recovery systems, are expected to reduce significantly the specific investment and overall operating costs. In the field of distillation, one of the more promising desalting options is that of low temperature multieffect distillation (MED) plants coupled to coal or nuclear power plants. A large prototype MED, using cheap alluminum tubing, has been recently built by Israel Desalination Engineering and is scheduled to start operation in the latter part of 1982. Various potential improvements of the MED process and optimized matching of system parameters with considered power plants will be analyzed. The two above discussed desalting options will be evaluated economically by assuming a common set of economic groundrules. The evaluation will be made for two stages of technological developments; current technology and projected technology. Recently made cost evaluations for large capacity plants, applying the two above-mentioned desalting options indicate specific investments in the range oa about $2/m 3 -year and unit water costs in the range of 60 to 70 cents/m 3, for current or near term technology and in the range of 40 to 60 cents/m 3 for projected technology. The two more important cost factors affecting competitiveness of these two options are unit energy and membrane replacement cost. A detailed analysis of these, as well as other cost factors, along with a breakdown of the cost effectiveness of the various projected technological improvements will be given and analyzed.

The Analysis and Design of Improved Control Systems for Recirculation Boilers

The importance of providing effective boiler control system performance in order to maintain high power plant availability is explained. Methods of predicting likely boiler perturbations are developed and the limitations of conventional boiler control systems investigated. Multivariable frequency response analysis methods are applied to the design and integrity analysis of an improved control system for an LMFBR (Liquid metal cooled fast breeder reactor) power plant boiler. This improved control scheme provides large stability margins and low interaction between loops. Its improved response to disturbances and resilience to system failures will contribute to greater plant availability.

The Value of Prototype Testing in the Development of the In-Vessel Handling Machine for FFTF

Refueling system components for LMFBR’s require a high degree of accuracy because of the need to function remotely without visual access. Also, they must have proven reliability to assure minimum plant outage for reactor refueling. The experience gained in the development of the in-vessel handling machine (IVHM) for the Fast Flux Test Facility reactor dramatically indicates that construction, testing, and modification of the design are an essential part of the development of this type of equipment. It is suggested that design and development schedules for this type of equipment must allow for production and testing of prototypes to assure that functional requirements of plant equipment will be achieved. The money spent on such testing must be considered as an investment rather than as a direct cost, with the return on investment being high reliability and consequently high plant availability. The IVHM is described briefly, and some specific lessons learned during prototype testing are presented.

Auslegungskriterien und Konstruktive Gestaltung der Sicherheitsumschliessung bei Siedewasserreaktoren

A survey on design, essential criteria and function of the containment system for AEG—Telefunken's present boiling water reactor product line is given. Safety enclosures of other BWR's are in most aspects similar with respect to the basic design principles, so this review might serve as a guide. The system presented consists of a steel primary containment with pressure suppression pool protected by reinforced concrete, of a leak-tight shell around the primary containment with a reventing system, of a reinforced concrete reactor building as secondary containment and of auxiliary systems for air conditioning and filtering and for decay heat removal. A study reveals that the smallest primary containment is the most economic, because primary containment size governs reactor building dimensions. Since the same fuel elements are being used for all plants — the power being proportional to their number —, the hight of the reactor pressure vessel is almost independent of thermal power. There seems to be a potential to size pressure suppression containments nearly independently of thermal power. Therefore the limits of compact construction are shown. Design criteria presented for the overall containment system consider access to components for operation, inspection and recurring tests in order to maintain high plant availability. They take into account system lay-out under all possible loads and operating conditions as well as quality assurance. They consider independence, separation and diversification of systems as well as redundancy. The criteria are aimed at system and — as a consequence — environment protection under accident and, if necessary, external hazard conditions. A flash-light is thrown on some new test results and on conservatively predicted performance of the containment system under reactor accident conditions, showing margins to keep the system safely under control even under highly degraded conditions.

Some Experiences on Computer Control Applications in Cement Plants

The paper describes briefly the cement manufacturing process and its i importance in today's world economy. It further sketches the successive steps of the introduction of process control to the operation of a cement plant. The optimization of the production process i s emphasized in the light of plant integration and automatization of its departments. Reduced process variability, lower production costs, increased power efficiency, and higher plant availability and production capacity are shown as results of plant automation. Some views are given on the influence of computer control on basic plant conception and on the standard of mechanical and electrical equipment suppliers. The paper elaborates somewhat on the impact of automation on plant operators and equipment suppliers as well as the role of the General Systems Designer and Consultant in applying modern technologies in designing sophisticated systems and in counseling the cement industry community.

High plant availability at Hunterston

High plant availability at Hunterston