Hydraulic Feed Systems

The feedstock was selected as typical samples of petroleum coke and hard coals with varying ash content. The feedstock composition data were taken from literature [16] and laboratory analyses. 

There have been investigations in alternative liquids substituting for the water, such as liquid CO2 [20], methanol, different kinds of hydrocarbons [21] and several kinds of oil contaminated water streams [22]. Although there is a clear potential for upgrading the efficiency, there has been no economic breakthrough of such alternatives. 

Recently the phase inversion-based coal-C02 slurry (PHICCOS) feeding system was presented as an alternative feeding method [23,24]. The main idea behind it is to prepare a coal-water-slurry that is compressed to 80 bar using conventional techniques. Downstream, the coal-water-slurry should be contacted with liquid CO2 at 30 °C. The principle of phase inversion postulates that a hydrophobic liquid, such as CO2, displaces water on the surface of the coal especially on the carbonaceous parts, also referred to as selective 

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TEMPERATURE CONDITIONS FOR PROCESS WITH A HYDRAULIC SULFUR FEED SYSTEM ARE SHOWN IN PARENTHESIS... 

Tellus System. A system for bricklayers working inside steel converters. A horizontal working platform is hydraulically raised or lowered by a centra] column, around which is provided a spiral automatic feed system to deliver bricks to the bricklayers. 

Injection units are rated in terms of the maximum injection pressure and injection volume available. Injection pressure is the theoretical maximum available at the downstream end of the screw. This is a function of the screw diameter and the foree aeting on it. It should not be confused, as it often is, with the hydraulic line pressure acting on the injection cylinder that supplies the force to the screw, nor should it be taken as the pressure available to fill the mold cavities. This is much less because of pressure losses in the nozzle and mold feed systems. Injection pressures are normally quoted in megapascals (MPa), atmospheric pressures (bar), or pounds per square inch (psi) (Table 7.3). 

These pumps are used as both feed pumps and dosing pumps. The drive system in most cases is pneumatic. Hydraulic drive systems are used when there are very demanding requirements. When used as a dosing pump, it must be remembered that the fleeting low pressure at the points of reversal is accompanied by a decrease in the applied quantity. The accuracy of gear pumps cannot be achieved. 

Once the maximum feed pressure has been reached, depending on the nature of the feed pump, then the feed system is closed and the tube press is isolated. Hydraulic fluid is now introduced between the elastomeric sleeve and the pressure vessel outside it, so as to squeeze the filter cake by meaus of the flexible sleeve. Squeezing pressures up to 140 bar are used, to dewater the filter cake, often to a degree of dryness where further thermal drying is unnecessary. The sleeve is then sncked off the cake by vacuum, and the inner tube is lowered free of its housing, and a pnlse of compressed air cracks the cake, which falls off the candle into a receiving vessel below it. 

Sedimentation Tanks These tanks are an integral part of any activated-sludge system. It is essential to separate the suspended solids from the treated liquid if a high-quality effluent is to be produced. Circular sedimentation tanks with various types of hydraulic sludge collectors have become the standard secondary sedimentation system. Square tanks have been used with common-wall construc tion for compact design with multiple tanks. Most secondary sedimentation tanks use center-feed inlets and peripheral-weir outlets. Recently, efforts have been made to employ peripheral inlets with submerged-orifice flow controllers and either center-weir outlets or peripheral-weir outlets adjacent to the peripheral-inlet channel. 

Most hydraulic systems have built-in sources of air. Leaky seals in gas-pressurized accumulators and reservoirs can feed gas into a system faster than it can be removed, even with the best of maintenance. Another lesser-known but major source of air is air that is sucked into the system past actuator piston rod seals. This occurs when the piston rod that is stroked by some external means while the actuator itself is not pressurized. 

There are many kinds of loss-lubrication systems. Most types of linear bearings are necessarily lubricated by this means. An increasingly popular method of lubrication is by automatic or manually operated one-shot lubricators. With these devices, a metered quantity of oil or grease is delivered to any number of points from a single reservoir. The operation may be carried out manually, using a hand-pump, or automatically, by means of an electric or hydraulic pump. Mechanical pumps are usually controlled by an electric timer, feeding lubricant at preset intervals, or are linked to a constantly moving part of the machine. 

The hydraulic pinch points in the feed preheat system are identified with a single-gauge pressure survey. The bottlenecks are often related to ... 

The decision to retrofit or install new filters is influenced by plant-specific factors such as the condition of the existing filters, compatibility of the filters to retrofit, availability of space within the plant, etc. Bayer s analysis of the costs and benefits of the retrofit compared to the investment in new filters did not show a clear favourite either decision could be justified. With regard to the rubber lining, gaskets, hydraulic system etc., the Kellys were in very good condition. Because of this, the decision was made to retrofit two of the filters and to use them in a separate brine circuit for the new electrolysers, with a second circuit feeding the amalgam plant. 

When operational characteristics of the oil systems were examined in detail, it was found that the oil supply came from the main turbine lube oil system. The operators said that after a start in cold weather they had trouble maintaining anything but the minimum lube oil temperature of 120°F (49°C) until the turbine was at power. The feed pump hydraulic coupling specifications indicated that a minimum temperature of 140-160°F... 

In the SBRs, the soluble organics in the hydrolysate are converted to a mixture of insoluble biomass (that can be settled and separated), water, and carbon dioxide. The ADP calls for three parallel SBR systems to ensure flexibility for low or high feed rates. Each SBR system has its own aeration system. The design criteria call for a hydraulic retention... 

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