High suction temperature

High suction temperature. Most installations will have the ability to inject a light hydrocarbon liquid upstream of the compressor s suction. This liquid vaporizes and, hence, cools the hot vapor flowing to the compressor suction. Typically, the vapor has overheated because the antisurge valve has been... 

Rotor sliding across bearings High discharge pressure Low suction flow High suction temperature... 

Pump Suction. The net positive suction head required (NPSHR) affects the resistance on the suction side of the pump. If it drops to or near the vapor pressure of the fluid being handled, cavitation and loss of performance occurs (13). The NPSHR is affected by temperature and barometric pressure and is of most concern on evaporator CIP units where high cleaning temperatures might be used. A centrifugal booster pump may be installed on a homogenizer or on the intake of a timing pump to prevent low suction pressures. 

Loss Factor. The loss factor is a correction fector for standard horsepower curves for high suction pressures at low ratios of compression. The bhp (brake horsepower) is obtained from the curves. Figures 12-21A-C. These curves are a plot of the n or k value of the gas versus the required brake horsepower (required to compress 1 million fti of gas at 14.4 psia and suction temperatures) for various ratios of compression. 

Where the ratio of suction to discharge pressure is high enough to cause a serious drop in volumetric efficiency or an unacceptably high discharge temperature, vapour compression must be carried out in two or more stages. Two basic systems are in use. 

Cold suction gas provides cooling for the compressor and is sufficient to keep small machines at an acceptable working temperature. Refrigerantshaving high discharge temperatures (mainly ammonia) require the use of water-cooled cylinder heads. Oil coolers are needed under some working conditions which will be specified by the manufacturer. These maybe water cooled or take refrigerant from the system. 

Abnormally low suction pressures will lead to high discharge temperatures, owing to the high compression ratio, and possible malfunction of other components. Air cooling coils may frost excessively, or water chillers freeze. 

Capacity.—Rates of gasification are high when temperatures are high f.e., when the cold gas efficiency is low. Average rates in suction producers are 5 to 20 lb. per square foot of fuel bed horizontal cross-section area per hour. A mean rate of 10 lb. may be expected for anthracite coal. 

The reversal of gas flow raised the suction temperature, which caused the motor driver to automatically trip-off on high temperature for surge protection. 

As in the Braun process, the size of the primary reformer is reduced and the size of the air compressor increased in the AMV process compared to more conventional process schemes. This is due to the operation with excess process air and with high methane leakage. Power consumption in the synthetic gas compressor is low because of the low synthesis pressure and the low suction temperature (gas direct from the low temperature Selexol CO2 removal unit), but this is compensated by increased power consumption for the compression of excess nitrogen and high power consumption in the refrigeration section. 

In some cases, blade-type rotary compressors are used in low temperature appHcations as high volume, low stage, or booster compressor (Fig. 9). These booster compressors are appHed at suction conditions varying from —87 to —20°C with compression ratios of 7 1 using CFC-12, HCFC-22, or ammonia. 

Now let s consider Figure 2-2. This is a pump in suction lift draining an opened tank that s 8 feet below the pump centerline. This pump is installed high on a mountain at 7,000 feet above sea level. The Ha is 26.2 feet. The Hsj is -8.0 feet. The water temperature is 50° F, so the Hvp is 0.411. The Hf is 1 foot and the Hi is 2.0. According to the information ... 

Usually, the closed liquid drain header is run as a separate line to the drum and provided with a high level cut-off valve with local manual reset. In some cases the closed drain system is segregated into a number of subheaders, as described earlier. Hydrocarbon liquids may be bypassed around the drum through a connection from the closed drain header directly to the pumpout pump suction, provided that the liquid can be routed to a safe disposal location, considering its vapor pressure and temperature. Emergency liquid pulldown connections, if provided, are routed to the blowdown drum via the closed drain header. 

At a constant speed, a constant volume of gas (at suction conditions of pressure and temperature) will be drawn into the cylinder. As the flow rate to the compressor decreases, the suction pressure decreases until the gas available expands to satisfy the actual volume required by the cylinder. When the suction pressure decreases, the ratio per stage increases and therefore the discharge temperature increases. In order to keep from having too high a discharge temperature, the recycle valve opens to help fill the compressor cylinder volume and maintain a minimum suction pressure. 

As flow rate to the compressor increases, the suction pressure rises until the volume of gas at actual conditions of temperature and pressure compressed by the cylinder equals the volume required by the cylinder. A flare valve is needed to keep the suction pressure from rising too high and overpressuring the suction cylinder, creating too high a rod load or increasing the horsepower requirements beyond the capability of the driver (see Chapter 11 for further discussion). 

Positive pumps are normally fitted with relief valves. These are not usually fitted to centrifugal pumps unless the process material is likely to explode if it gets too hot. As an alternative to a relief valve, such pumps may be fitted with a high-temperature trip. This isolates the power supply. Or a kick-back, a small-diameter line (or a line with a restrietion orifice plate) leading from the delivery line baek to the suction vessel, may be used. The line or orifice plate is sized so that it will pass just enough liquid to prevent the pump from overheating. Small-diameter tines are better than restriction orifice plates as they are less easily removed. 

After cooling, the solid is filtered by suction and washed with alcohol at 96°C. The product is dried at ordinary temperature in a high vacuum. A colorless solid is obtained (quantitative yield), which is completely soluble in water. The aqueous solution is strongly alkaline in reaction when acidified with acetic acid and heated on a water bath, it yields a precipitate of 7-chloro-5-phenyl-2-oxo-2,3-dihydro-1 H-benzo[fl-1,4-diazepine. 

The product is hydrogenated in 4,000 cc of ethanol at room temperature and under normal atmospheric pressure with a catalyst prepared In the usual manner from 400 g of Raney nickel alloy. The calculated amount of hydrogen is taken up in approximately 75 hours. After filtration and evaporation to a small volume, the residue Is distributed between 1,000 cc of chloroform and water each. The chloroform solution is then dried over sodium sulfate and evaporated to a small volume. Precipitation of the hydrogenation product with petroleum ether yields an amorphous white powder which Is filtered by suction, washed with petroleum ether and dried at 50°C In a high vacuum. 1. athyl-2-podophyllinic acid hydrazide is obtained in a practically quantitative yield. 

Hydrocarbons, hot Single suction, often of the special type called refinery pumps, designed particularly for high temperature service. Closed with large inlets. 

Hot corrosives Single suction, with many refinery pump types also used here because of high temperatures and corresponding suction pressures. ... 

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