Bypass Pipe Research Articles

APPLICATION OF ER FLUIDS IN PNEUMATIC CYLINDER SPEED CONTROL

The variable speed rodless cylinder system has tow magnet type rodless cylinders which aremechanically coupled with both slide tables mounted on the cylinder tubes. One cylinder is drivenby pneumatic pressure, and the other is filled with the ER fluid. The bypass piping is laid such thatthe ER fluid circulates as the piston move. An electrode which located in the middle of this bypasspiping is applies an electric field to the ER fluid. The viscous resistance of the ER fluids againstthe pneumatic driving force is operated by the applied electric field to the ER fluid. In consequencethis system enable the pneumatic cylinder to be controlled smoothly any speed setting not only atstart up and stoppage but also any position of the stroke.

Preliminary Optimal Design Model for Wastewater Treatment Plant

A mathematical programming model for the least-cost design of a wastewater treatment plant is presented for the preliminary screening of projects. This model represents the treatment plant as a network of unit processes and uses a cost function that depends not only on waste removal efficiency, but also on influent flow rate and concentrations of various effluent quality criteria, such as biochemical oxygen demand, phosphorus, and nitrogen. The model also incorporates the concept of generalized bypass piping, allowing a bypass after each unit process, which makes it possible to enhance the flexibility and economy of designs. The proposed approach facilitates a number of important decisions for the optimal design of wastewater treatment plants, especially selection of the combination of unit treatment processes, their sizes and removal efficiency levels, and the flow distribution. Since the cost functions are simplified in this model, more elaborate mathematical programming models should be used to reach a final decision.

Evaluation of prefailure stages of heat-resisting steels by the eddy-current method : 39119 Volkov, B.I.; Agafonov, V.A.; Bologov, G.A.; Fedorov, A.L. Soviet Journal of Nondestructive Testing, Vol. 23, No. 6, pp. 417–422 (Feb. 1988)

Experiments were carried out to evaluate the possibilities of evaluating, by the nondestructive eddy current method, early stages of damage in heat-resisting chrome-molybdenum-vanadium steels used in the conditions of development of the creep deformation process. A correlation was found between the parameters of the signal of eddy current attached transducer and the degree of damage in the metal of bends of steam by-pass pipes of 12Kh1MF steel can be evaluated using, as the information-carrying parameter, the modulus of the signal of the eddy current attached transducer.

Reconstruction of asphalt shaft waterbars of contraction joints of sections of the powerhouse at the lower Kama hydroelectric station

The Lower Kama hydroelectric station on the Kama River, the foundation of which is composed of ancient alluvial river deposits, is a typical run-of-river hydrostation with respect to design and layout. The 486-mtong powerhouse, 71-m-long overflow dam, and earth dam form a single barrier. The powerhouse is combined with outlets and is divided into eight sections. Two vertical units are located in each section. The sections are separated by 30-cm-wide contraction joints. The cavity of the contraction joints between sections is sealed on the upstream and downstream sides by asphalt shaft waterbars Nos. 12 and 14, the design of which is shown in Figs. 1 and 2. The rooms of the powerhous along the joints are sealed by contour {elastic) waterbars. The shaft waterbars along the foundation slab of the sections are connected to horizontal asphalt waterbars of a U-shaped profile. On the upstreamside a spare shaft is made in the joint for the possibility of making asphalt waterbar No. 13. The cavity of the joint during normal operation is filled with water to elevations corresponding to the lower pool levels and elevation of the bypass (pipe d = 100 mm), which provides discharge of water seeping into the joint into the lower pool, bypassing shaft waterbar No. 14. The capacity of the bypass when k = 1 m is 1 ma/min. During temporary operation of the hydrostation at an intermediate reservoir elevation of 62 m considerable leaks into the joint were observed, in connection with which the water levels for a number of joints exceeded the design. This led to complications in operating the equipment, including flooding of the cable galleries. Attempts to heat the asphalt waterbars by an electrical heating system embedded in the waterbar structure did not yield positive results as a consequence of breaks in the circuit of the heating electrodes during Construction works. In 1983 the Kama Hydroelectric Station Construction Association {Kamges~nergostroi) turned to the Institute for Special Operations (Gidrospetsproekt) and the State All-Union Trust for Reinforcement of Foundations and Structures (Gidrospetsstroi) with the request to give recommendations and to perform repair and restoration works on the shaft waterbars in order to provide the design water level in the cavity ofthesectionjoin ts.

A Fundamental Investigation of the Capsule Transport : 4th Report, Numerical Analysis of Motion of Accelerating and Decelerating Capsules

An expression was obtained for the fluid drag on a capsule having two end-plates. Capsule motion in the start region where it was accelerated was calculated numerically based on the equation of motion in consideration of the characteristics of a blower and the air discharge through a by-pass pipe. Calculation was also made for stopping the capsule in the closed end region of the pipe utilizing the reaction of the air compressed by the capsule. It was found that the calculations agreed well with experimental results.

Cablegation: IV. The Bypass Method and Cutoff Outlets to Improve Water Distribution

ABSTRACT TWO techniques of improving the water distribution characteristics of cablegation systems are proposed and evaluated. The bypass method, which largely eliminates the problem of end effects, involves starting the plug at the first outlet and initially bypassing most of the flow to the downstream end of the pipeline, which is plugged. As the plug moves down the pipe, the bypass flow gradually decreases to zero. This method nearly equalizes the inflow distribution to all furrows and allows the use of a constant outlet opening size. The bypass can be accomplished by using a parallel bypass pipe and weir, or with a flow-through bypass plug. The bypass plug appears to be the lower cost method and is as effective as the weir in controlling the bypass. The second technique deals with the low outlet flows during the fmal stages of a set which are insufficient to reach the end of the furrows such that excess water is applied to the upper ends of the furrows. Two types of cutoff outlets, a gravity valve and a siphon type outlet were designed to abruptly cut off the flow at about the same time that runoff ceases, thus maximizing the uniformity of infiltration. The cutoff outlets are recommended for soils having relatively high sustained intake rates.

Towards an elastic-plastic fracture mechanics predictive capability for reactor piping

Intergranular stress corrosion cracks have been discovered in the recirculation bypass piping and core spray lines of several boiling water reactor (BWR) plants. These cracks initiate in heat-affected zones of girth welds and grow circumferentially by combined stress corrosion and fatigue. Reactor piping is mainly type 304 stainless steel, a material which exhibits high ductility and toughness. A test program described in this paper demonstrates that catastrophic crack growth in these materials is preceded by considerable amounts of stable crack growth accompanied by large plastic deformation. Thus, conventional linear elastic fracture mechanics, which only applies to the initiation of crack growth in materials behaving in a predominantly linear elastic fashion, is inadequate for a failure analysis of reactor piping. This paper is based upon research initiated by a need to develop a realistic failure prediction and a way to delineate leak-before-break conditions for reactor piping. An effective engineering solution for the type of cracks that have been discovered in BWR plants was first developed. This was based upon a simple net section flow stress criterion. Subsequent work to develop an elastic-plastic fracture mechanics methodology has also been pursued. A survey of progress being made is described in this paper. This work is based on the use of finite element models together with experimental results to identify criteria appropriate for the onset of crack extension and for stable crack growth. A number of criteria have been evaluated. However, the optimum fracture criterion has not yet been determined, even for conditions which do not include all of the complications involved in reactor piping.

Buckling and rupture of the double bellows expansion joint assembly at Flixborough

The cause of the Flixborough explosion was traced to some temporary pipework. A bypass pipe assembly collapsed, allowing large quantities of volatile cyclohexane to escape. At an early stage in the accident investi­gation, it was realized that this pipework must have failed, but the mechanism by which it had done so was not apparent. A detailed experi­mental and theoretical study had to be carried out to determine what went wrong. The temporary bypass pipe assembly consisted of a dog-leg shaped pipe attached by flexible bellows expansion joints to reactor vessels at each end. It was found that its failure was initiated by a form of structural instability of the bellows called squirming, and that this slightly bent the dog-leg pipe, which then collapsed by jack-knifing at one of its mitre joints. Separate experimental tests showed (i) that the bellows would have remained intact after squirming if the connecting pipe had not jack-knifed, and (ii) that, if the dog-leg pipe had not been bent by squirm­ing, it would not have jack-knifed. It was the combination of bellows and pipe together which proved dangerous, even though each alone was safe. This paper explains the mechanics of squirming and jack-knifing, and describes how a detailed quantitative picture of the original failure was eventually established.

An optimization model for regional water quality management

A nonlinear programing model for water quality management is developed and applied to the case of the upper Hudson River. The model is formulated as a geometric programing problem. It is shown that this formulation permits the simultaneous consideration of waste treatment processes, bypass piping, flow regulation, and artificial aeration in determining a least‐cost solution to a given water quality management problem.

Optimal Planning for a Thermal Discharge Treatment System

The characteristics and economic implications of thermal pollution are considered within the context of the planning of a treatment system for a series of hypothetical nuclear power plants that are to be located adjacent to a river. It is assumed that these power plants will discharge sufficient heated cooling water to make these treatment facilities necessary. The problem that is being considered is to determine the optimal planning of a treatment system. The objective of the planning procedure is to minimize the total annual cost for the construction and operation of the entire system. The constraint on this minimization process is not to violate a maximum temperature requirement within each reach or section of the river. The problem is solved by considering the effect that a bypass‐piping system has on temperatures within the river. The technique of bypass piping consists of piping waste water downstream to reaches of a river where the regenerative powers of the physical system have reduced the level of pollution to the extent that more waste water may be disposed. By noting that the bypass‐piping system allows the beginning and end temperatures of a section of the river to be controlled, a procedure can be developed for separating the optimization model of the entire system. This model is separated into a set of small subproblems that are solved by simulation and a system problem that is solved by dynamic programing. The results of the implementation of this model showed that the bypass‐piping system significantly reduced the cost of the entire treatment system.

Multigoal Water Quality Planning Model

A nonlinear programming river basin model is presented which can be solved for the least-cost combination of treatment strategies to meet some predetermined quality goals. The model presented is unique in two respects: (1) the interaction of temperature and dissolved oxygen levels is explicitly modeled; and (2) five alternative treatment strategies are examined. Although both the behavior of thermal and oxygen demanding wastes have been modeled in a river, they are always modeled independently even though it is well known that the level of the temperature affects the rates of oxidation reactions and the saturation level of oxygen. In the model presented these relations are explicitly assumed. The treatment strategies examined simultaneously are on-site treatment, regional treatment, by-pass piping, flow augmentation, and cooling towers.

Hydromechanical complex at Serebryansk No. 1 Hydroelectric station

1. The hydraulic testing of the turbine penstock permitted the elimination of several defects detected in its shell. Of the two types of bulkhead flanges used in the tests, the erection of the plane flange is considerably simpler. 2. The installation of a drain ahead of each line of the penstock permits the water leaking through the gate seals, when the gate is closed, to be intercepted and discharged through outlet pipes into a ditch. The use of such drains can be recommended at similar hydroelectric stations. 3. Because the removal of the internal bracing of the transition chambers in the penstocks was carried out by oxygen flame cutting, which causes local heating of the lining and its peeling away from the concrete, the number of braces should be reduced to a minimum and external ribs of sufficient stiffness adopted instead. 4. In addition to by-pass pipes connecting the draft-tube chambers, it is also desirable to provide pipes for the direct communication of the draft tubes to the tailwater, for the equalizing of water levels before raising a maintenance gate, regardless of whether or not there is water in the other pipes.

MODELING AND CONTROL OF THE POLLUTION OF WATER RESOURCES SYSTEMS VIA MULTILEVEL APPROACH1

ABSTRACT. The problem of modeling and control of water pollution is considered. A general mathematical model, where the pollution effluent is discharged directly into the river, into the lake, or into a bypass pipe leading to an advanced Waste Water Treatment (AWT) plant, is developed. The Water Resource System (WRS) under consideration is decomposed into N subsystems. The pollution effluent input vector to each subsystem includes the water quantity and different water characteristics such as BOD, DO, pH, conductivity, temperature, algae, phosphates, nitrates, etc. Treatment cost functions and quality transition functions as well as system model constraints are introduced, where all functions can be nonlinear. A system Lagrangian is formed to incorporate the system constraints and coupling. The Lagrangian is decomposed into N independent subsystems, and a two level optimization methodology is introduced. Each subsystem is independently and separately minimized at the first level assuming known Lagrange multipliers. At the second level, the total Lagrangian is maximized with respect to the Lagrange multipliers using optimal values for effluent inputs from all subsystems obtained from the first level. Economic interpretation on the Lagrange multipliers reveals that they are merely prices imposed by the central authority (second level) for the pollution caused by the subsystems. Advantages of the multilevel approach are discussed.

流送パイプにおける磁選

This paper is the first piece of a serial work dealing with the results of a study made on a new type magnetic separator. It is devised to separate iron sands by-product from a slurry carried through a pipe line.The results obtained from this investigation are as follows.(1) The ratio of enrichment and the recovery of separated iron sands are subjected to the effect mainly from the shape of magnets, the arrangement of magnetic poles and the rate of volume flow in the by-pass pipe.(2) The ratio between the rate of volume flow in the bypass pipe and that of in the main pipe, ranging from 0.0151 to 0.0454 is sufficient for the purpose of magnetic separation.(3) When the magnetic separation has been carried out under the condition of mean magnetic flux density of 1, 000 gauss and 3-4% assay of feed, the ratio of enrichment becomes 16.5, the recovery 56% and the yield about 3 to 4%, respectively.