Dewpoint conditions

While these curves apply only to the specific conditions listed, some generally applicable obaerva-atlons should be made. With an inlet pressure of 2425 psla a distance of at least 200 miles would be required for the gas to reach dewpoint conditions for the higher dewpoint gas shown (49°F at 1000 psla). 

Diaphragm pump, 142, 143 Deentrainment commercial equipment, 619 cyclone dimensions, 620 cyclones, 616,620,621 empty drums, 615,617 wire mesh nads. 615.616.618.620 Densities, hulk, data, 677-679 Desalination, 632 performance, 640 Design basis, 12 questionnaire 13, 14 Detergent manufacture, 35 Dewpoint conditions, 376 calculation, 378... 

Flexibility. Temperature and dewpoint conditions in the hopper can be set to exactly match the material being processed. 

Because Norske Shell was using these turboexpanders in a dewpoint control process, it was necessary to factor in other specific conditions. For instance, these mrboexpanders could be exposed to possibly violent process transient conditions. For this reason, the magnetic bearings required a flux control system to increase the response capability, which was developed by the original equipment manufacturer in concert with the magnetic bearing manufacturer. The load factor of... 

Saturated air is difficult to measure accurately a deviation of 3-5 K must be accepted. In some air conditioning systems, very humid air may condense on surfaces below the dewpoint temperature of the air. Poorly insulated ducts containing humid air can cause serious problems. See Fig. 9.57. 

Moisture may be removed from air by passing it over a surface which is colder than its dewpoint (see Figure 24.9). In air-conditioning systems this is a continuous process, providing that the moisture condenses out as water and can be drained away. If the apparatus dewpoint is beIowO°C, the moisture will condense as frost, and the process must be interrupted from time to time to defrost the evaporator. 

Polarization citrve for PEMFCs with two different cathode diffusion layers carbon fiber paper with one MPL and carbon fiber cloth with two MPLs. Operating conditions ceU temperature of 85°C, O2/H2 dewpoint temperatures of 90/100°C gas pressures of 2 atm. CFP DL was a TGP-H-090 with 20 wt% PTFE in the MPL. CCs were PWB-3 from Stackpole cathode CC had 15 wt% PTFE in the MPL near the CL and 30 wt% PTFE in the MPL near the flow field. The anode CC had 15 wt% PTFE in both MPLs carbon loading on the MPL was not specified. The catalyst Pt loading was 0.4 mg cm and the Nation loading was 1.1 mg cm for all catalyst layers the membrane was a Nation 115. (Modified from E. Antolini et al. Journal of Power Sources 163 (2006) 357-363. With permission from Elsevier.)... 

This nay be a difficult specification to meet on offshore platforms in the North Sea, and such a stringent hydrocarbon dewpoint requirement nay not be necessary for the gas pipeline operating conditions likely to be utilized in the North Sea. 

If produced gas is to be injected back into the producing formation or seme other formation, rather than delivered to a gas pipeline, it may be possible to inject the third product stream into the injection gas stream, or to inject it separately into the reservoir. However, this may be only a temporary solution to the problem, since the intermediate components could be reproduced again, and may be in higher concentrations than they were the first time. If injected gas is ultimately delivered to a gas pipeline, and if intermediate components have been injected also, the gas conditioning problem to meet dewpoint requirements will be more difficult at a later date. 

Often it is known or suspected that future platform operating requirements nay change, which requires separation system flexibility. For example, the initial plan may be to inject gas into the producing field, but a gas pipeline outlet for the gas may be expected several years later. At that time the gas would not have to be delivered at as high a pressure, but more extensive gas conditionlng would be required to meet hydrocarbon dewpoint requirements It may be possible to utilize surplus gas conpression horsepower for gas conditioning purposes at that time As another example, it may be planned to initially load low vapor pressure crude oil into tankers at the offshore platform, but later after pipeline completion to deliver high vapor pressure crude oil to the pipeline. 

The dewpoint of a gas is a direct function of the concentration of the various hydrocarbon components in the gas. Increasing concentrations of any hydrocarbon heavier than methane will increase the tendency of liquids to condense at some pressure-temperature condition, but small quantities of pentanes and heavier components create more liquid condensation problems than somewhat larger quantities of intermediate hydrocarbons such as butanes, propane, and ethane. The heavier the hydrocarbon, the greater will be the effect of a given quantity on the dewpoint of the gaa. 

For any fixed gas composition, the dewpoint la a function of both the pressure and temperature of the gas. The question of what gas dewpoint limitation is necessary to prevent condensation of liquids in the gas pipeline Introduces a somewhat complex problem of vapor-liquid phase equilibrium under high pressure pipeline conditions, and the interrelated problem of the flowing pressure-teoperature profile for the gas in a pipeline. Gas of different compositions will behave somewhat differently, but we can... 

As previously mentioned, most onshore gas pipeline systems in the USA and Europe operate at pressures in the 500 to 100C psia range. Ground temperatures at pipeline depth approach J32°F in winter In many areas, so it is possible for the gas temperature to approach this level. Both of the gas streams whose dewpoint curves are shown on Figure 1 would oondense liquids at such conditions. In the North Sea, however, the environmental conditions will be different, and we also expect that gas pipeline systems will be designed to operate at higher pressure levels. 

The effect of retrograde condensation on a crude oil component such as octane is particularly significant, and small amounts of these heavier components if left in the gas also have a great effect an hydrocarbon dewpoints. Even with extensive gas conditioning cooling it is difficult to remove all crude oil ccanpcnenta from the vapor streams at a pressure of 1500 psl. Note that the K-value for octane at 0°F and 1500 psi is not as low as at 100°F and 1000 psi. 

The mixture will be all gas if the selected temperature is greater than the dew-point temperature or the selected pressure is less than the dewpoint pressure. The lower dashed line on Figure 12-1 shows that no solution is obtained for these conditions. This situation occurs when Sz/Kj is less than 1.0. 

At temperatures and pressures between those of the bubblepoint and dewpoint, a mixture of two phases exists whose amounts and compositions depend on the conditions that are imposed on the system. The most common sets of such conditions are fixed T and P, or fixed H and P, or fixed S and P. Fixed T and P will be considered first. 

A C02-CH4 methane process gas stream, similar to a typical high CO2 natural gas has been under test by SEPAREX for CO2 removal in a 2-in. diameter element pilot plant since September 1981. The feed gas contains 30% CO2 and is delivered to the membrane test unit at 250-450 psig under ambient temperature conditions. The objective of the system is to reduce the CO2 level of the methane to less than 3.5%. The membrane system consists of 5 pressure tubes in series, each tube containing three 40-in. long elements. The gas is conditioned to maintain it at a minimum of 20°F above the dewpoint. The system was operated at a variety of flow rates, pressures, recoveries and temperatures. Selected data are presented in Figures 6 through 8. 

Clean, conditioned gas stripped of heavy hydrocarbons 0.5-1.0 MMscfd Dewpoint 45 F... 

Blmodal size distributions of the H-Coals showed little change at reduce air conditions. Emissions of S0a from the coal derived liquids were also quite low (with correspondingly low acid dewpoints) as these chemically cleaned fuels contained only a fraction of the sulfur normally found 1n petroleum liquids (0.15% versus 2.29% typically). 

The problems of interest are finding the conditions for onset of vaporization, the bubble-point for the onset of condensation, the dewpoint and the compositions and the relative amounts of vapor and liquid phases at equilibrium under specified conditions of temperature and pressure or enthalpy and pressure. The first cases examined will take the A, to be independent of composition. These problems usually must be solved by iteration, for which the Newton-Raphson method is suitable. The dependence of K on temperature may be represented adequately by... 

Depending on the particular operation, offgases from the incinerator may range from 1100° to 2100°F. Typically, the gases are sent to a conditioning chamber to lower the temperature to 500° to 600°F before they enter a scrubber. While the incinerator is in operation, the gases may remain above the acid dewpoint and corrosion problems will be minimal. But because most incinerators are cyclic operations with frequent periods of idleness, gas condensation in the inlet and outlet scrubber ductwork during shutdowns can cause serious deterioration. 

Even though the gases entering a stack may be above the acid dewpoint and safe from a corrosion point of view, if the stack is tall (>200 ft), the temperature may drop below the dewpoint once it reaches the top. This presents a familiar problem to many lining materials. The wet condition at the top of the stack causes lining failure and forces frequent maintenance. With the borosilicate glass block from bottom to top, the stack designer need not try to determine the transition point and then specify different materials for each section of the stack. 

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