Pressure Water Accumulators

A hydraulic accumulator is supplied with pressure water whose economic pressure is in the region of about 200 atmospheres, by one or more pumps (see p. 138). The complete station is suitably installed separate from the presses in a room of its own. 

The water operates in a closed circuit it flows from the supply tank to the pumps which feed it into the accumulator. The latter supplies it through controls to the press and on completion of the power stroke the water passes through the controls into a low -pressure air-vessel and hence via an overflow valve back into the supply tank. 

The two main types are the air-loaded and the dead-weight accumulator. 

Dead-weight accumulators are obsolete and only very few have been constructed during the past 20 years. They consist of a vertically arranged cylinder whose piston is loaded by a heavy weight made up of cast-iron plates or a vessel filled with ore or scrap metal. The weight depends on the water pressure required it amounts, for example, to about 140 tons at a piston diameter of 300 mm and an operating water pressure of 200 atm. The drawbacks of this accumulator type are its large overall 

The air-loaded accumulator generally consists of a water bottle and a battery of air bottles connected to the former (Fig. 176). The ratio of the volume of water to the total volume of the bottles is as a rule about 1 10. The pressure drop between highest and lowest water level, i. e. on withdrawal of the total usable contents of pressure water, is about 10 to 12%. The compressed air serves the only purpose of loading the water to the required pressure and consequently, the air is not consumed. 

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Fig. 72 shows the hydraulic circuit diagram of an extrusion press operated from a pressure water accumulator. The press has separate controls for the piercing- and main cylinders. When w orking without piercer, the control lever of the piercer control is set to return. When the lever of the main control is shifted to advance, the filling water flows from the air-vessel through the filler valve into the main cylinder and through... 

Fig. 161. Pressure water accumulator for combined tube and rod extrusion press shown in Fig. 1.58...

Fig. 176. Pressure water accumulator with two water bottles fed by three horizontal pumps (By Hydraulik, Duisburg)...

Simplified Cycle. A simplified fossil steam cycle appears in Figure 19. The water accumulates in the bottom of the condenser, called the hotweU. It goes through a feed pump to pressurize it. The pressurized water passes through one or more feedwater heaters, which raise the temperature. The water then enters the boiler where heat from the fuel converts it to steam. The steam expands through the engine, usually a turbine, which extracts work. In the middle of the turbine some of the steam is extracted to supply heat to the feedwater heater. The remainder expands through the turbine and is condensed. The rejected heat is carried away by the condenser coolant, which is usually water, but sometimes air. The condensed steam then returns to the... 

High-pressure fluid flows into the low-pressure shell (or tube chaimel if the low-pressure fluid is on the tubeside). The low-pressure volume is represented by differential equations that determine the accumulation of high-pressure fluid within the shell or tube channel. The model determines the pressure inside the shell (or tube channel) based on the accumulation of high-pressure fluid and remaining low pressure fluid. The surrounding low-pressure system model simulates the flow/pressure relationship in the same manner used in water hammer analysis. Low-pressure fluid accumulation, fluid compressibility and pipe expansion are represented by pipe segment symbols. If a relief valve is present, the model must include the spring force and the disk mass inertia. 

As briefly mentioned in Section 4.3.S.2, Atiyeh et al. [152] performed water balance measurements and calculations to determine the effect of using DLs with MPLs (on either or both cathode and anode sides). In their fuel cell test station, water collection systems were added in order to be able to collect and measure accurately the water leaving both anode and cathode sides of the fuel cell. Based on the operating conditions (e.g., pressures, temperatures, relative humidities, etc.) and the total amount of water accumulated at the outlets of the test station, water balance calculations were performed fo defermine the net water drag coefficient. Janssen and Overvelde [171] used this method to observe how different operating conditions and fuel cell maferials affected... 

The main constituent of Mang Xiao is sodium sulfate. As the intestines cannot absorb sulfate, it stays in the intestines and increases osmotic pressure to accumulate water in the intestines, stimulate them and soften the feces. 

Pressure relief valves play an important role in LNG piping systems. Any section of LNG piping that can trap LNG must have a pressure relief valve to prevent failure of that section of pipe should all the LNG vaporize. These pressure relief valves are similar to those used on LNG storage tanks. Spring-loaded valves that reseat following a reduction in pressure are preferred to those that do not and vent all the LNG in that line. Pressure relief valves should be protected from water accumulation to prevent freezing in the open position since the LNG vapor that is released will likely be very cold. 

A transparent PEM fuel cell with a single straight channel was designed by Ma et al.11 to study liquid water transport in the cathode channel (this study is also mentioned in Section 2.5). The pressure drop between the inlet and outlet of the channel on the cathode side was used as a diagnostic signal to monitor liquid water accumulation and removal. The proper gas velocities for different currents were determined according to the pressure drop curves. 

The saturated zone is formed by porous material in which all the pore spaces are filled with water. The water table is defined as the depth at which pore water pressure equals atmospheric pressure. If a hole is dug down to the saturated zone, the location of the water table can be easily determined it is at the depth to which water accumulates in the hole. In coarse porous material, the location of the water table itself very nearly approximates the transition between saturated and unsaturated material in a fine-textured porous material, enough water may move upward by capillarity to cause complete saturation of a measurable thickness above the water table (the capillary fringe). 

Most of the basic conditions and parameters of the simulation are the same as in Table 5 those which are different are given in Table 6. The map of the cell is presented in Fig. 29. Application of a pressure gradient changes the distribution of water vapor concentration at the cathode dramatically. Due to the pressure gradient water accumulates in front of the Red channel. This leads to a significant flux of water into this channel (cf. Fig. 30). Under current density 0.4 A cm-2 the flux of water is about 0.1 A cm-2 (cf. Fig. 30). The Red channel, therefore, collects water. 

The most straightforward synthesis of acyclic carbonates from C02 is its dehy-drative condensation with alcohols (Scheme 6.7). This reaction is catalyzed by a variety of soluble and solid catalysts, with organometallic Sn derivatives such as Bu2Sn(OMe)2 playing a significant role. Typical reaction conditions include 140-180°C and up to 300 bar C02 pressure. A particular problem is that water accumulation affects unfavorably the chemical equilibrium furthermore, it acts as a catalyst poison and therefore it must be removed from the reaction mixture. Orthoesters (e.g., trimethyl orthoacetate) and acetals (e.g., dimethyl acetal) that work as internal water scavengers can be used as starting materials instead of the... 

In the case of the inner planets, there was no dissipation of those gaseous compounds that either condensed on (depeding on temperature and pressure conditions) or chemically reacted with the solid and liquid phases. Under the conditions of the proto-Earth water accumulated, an event of major importance. It was this accumulation that made the formation of the biosphere possible, the evolution of which led to the appearance of a thinking species, man. 

BCGSs normally have large in-place hydrocarbon volumes but very low recovery factors (Masters 1979, 1984, 2001 Nuccio et al. 1992). Unlike conventional hydrocarbon systems, gas accumulations are sometimes downdip from normally-pressured, water-bearing reservoirs (Masters 1979, 1984, 2001 Nuccio et al. 1992). Furthermore, gas accumulations often do not have a downdip water contact (Law 1984a,b, 1985 Masters 1979, 1984, 2001). 

When the column feed passes through a heater (e.g., a refinery fractionator or vacuum tower), any water lying at low points in the coils must be blown out prior to startup. In multipass coils, water must be separately blown out of each pass block valves are sometimes installed on each pass to permit this (7). If blowing into the tower, it must be performed when the tower can still tolerate water. The coils must be kept hot and/or purged from then on to prevent condensation. One pressure surge incident (7) occurred when water accumulated in one heater pass entered a refinery vacuum tower which was under full vacuum and circulating 280°F oil. 

Tower trays were repeatedly upset due to pressure surges resultii from water accumulating in the tower during short unit outages. The source of water was condensation of purge steam used under the cohmm relief valves to prevent their inlets from plugging. 

Coluinn consisted of two secticms, separated an upward bulging internal head, which served as a draw pan. The liquid outlet was 3 in above the lowest po water accumulated below that. When hot oil later filled the pan, a pressure surge occurred and damaged trt ... 

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