Pump-down processes

At the beginning of a pump down process, the gas ballast pump should always be operated with the gas ballast valve open. In almost all cases a thin layer of water will be present on the wall of a vessel, which only evaporates gradually. In order to attain low ultimate pressures the gas ballast valve should only be closed after the vapor has been pumped out. LEYBOLD pumps generally offer a water vapor tolerance of between 33 and 66 mbar. Two-stage pumps may offer other levels of water vapor tolerance corresponding to the compression ratio between their stages -provided they have pumping chamber of different sizes. 

These flow resistance considerations are important to vacuum systems when through these, gas flows are restricted in connection with pump-down processes or venting processes or when measuring leaks, for example. 

Generally this type of unit serves to compress gases from vacuum up to atmospheric pressure. Often after initial startup, the unit must pump-down the system (such as a closed process system of vessels) by gradually bringing down the... 

Many systems are shut down for periods of the year, either for process closure or if not required in winter. The advice of the supplier should be sought as to the correct procedure. In the case of refrigerant circuits, it is advisable to pump down into the receiver or condenser to minimize leakage losses. Water towers should be drained in winter in this climate, if not in use, and the tank heater disconnected. 

Frasch process for mining sulfur. Superheatad watar at 165°C is sent down through the outer pipe to form a pool of molten sulfur (mp = 119°C) at the base. Compressed air, pumped down the inner pipe, brings the sulfur to the surface. Sulfur deposits are often 100 m or more beneath the earth s surface, covered with quicksand and rock. 

The metal ions are often added as salts of organic compounds, which form chelates. This causes a delayed gelation. Likewise, the components of the gelling agent are pumped down in two stages. Some metal cations cannot be used with brines. On the other hand, brines are often produced from wells, and it is desirable to find uses for them to avoid disposal processes. 

Drilling muds are fluids that are pumped into the bore holes to aid in the drilling process. Most are water based and contain barite, hgnite, chrome lignosulfate, and sodium hydroxide [11], but oil-based drilling muds are still used for economic and safety reasons [12]. Used muds can be removed by vacuum trucks, pumped down the well annulus, or allowed to dewater in pits, which are then covered with soil or disposed of by land farming. 

The magnitude of the allowable temperature for the bake-out process in question will, indeed, be determined essentially by the material in the chamber. Precise pump-down times can then be estimated by calculation only if the quantity of the evolving and pumped vapors is known. Flowever, since this is seldom the case except with drying processes, a quantitative consideration of this question is abandoned within the scope of this publication. 

The backing pump must be suitably rated with regard to the volume of the vessel and the desired pump-down time. This pump-down time is arranged according to the desired process duration if the process is to be finished after 12 -15 h, the pump-down time should not last longer than 1 h. The size of the backing pump may be easily calculated according to Section 2.3.1. 

The pressure dependence of the pumping speed is taken into account in the nomogram and is expressed in column ( ) by p p. If the pump pressure p p is small in relation to the pressure Pg ji which is desired at the end of the pump-down operation, this corresponds to a constant pumping speed S or during the entire pumping process. 

A pilot-scale demonstration remediating harbor sediment was conducted 1 year before the SITE demonstration. Based on the pilot-scale demonstration, the processing costs for a fuU-scale, 110-ton/day unit were projected to be 230/ton (September 1992 U.S. dollars). It is assumed that the unit will be down approximately 30% of the time for maintenance and design improvements in the first year of operation. Based on this system availability, 28,105 tons can be processed in one year. This cost included estimates for variable costs, fixed costs, and deprecia-tion/insurance. Variable costs include diesel fuel for a mobile generator, hydrogen, and caustic. Fixed costs include labor diesel fuel for pumps, heaters, process equipment, and instrumentation propane, water and sewer and parts and supplies. Depreciation/insurance costs include capital cost depreciated over a 3-year period, general insurance costs, and pollution liabihty insurance. This analysis does not include costs for setup and demobilization (D128007, pp. 5.12-5.14). 

What approximate composition of DDAB surfactant in water would you recommend to pump down an oil well to improve oil recovery if the main cost of the process was the cost of the surfactant ... 

A schematic of a batch parametric pumped adsorption process is sketched in Figure 19.12(a), whereas Figure 19.12(b) shows the synchronized temperature levels and flow directions. At the start, the interstices of the bed and the lower reservoir are filled with liquid of the initial composition and with the same amount in both. The upper reservoir is empty. The bed is kept cold while the liquid is displaced from the interstices into the upper reservoir by liquid pumped from the lower reservoir. Then the temperature of the bed is raised and liquid is pumped down through the bed. Adsorption... 

Both field and laboratory observations are consistent with the idea that dissolution can proceed faster than precipitation in carbonate sediments (also see Pytkowicz, 1971 Berner et al., 1978 Moulin et al 1985 Burton and Walter, 1987), and that the pore waters reach steady-state ion activity products close to those of the most unstable phase (dissolution processes will be discussed later in this chapter). Carbonate ion may be "pumped" down to values at saturation with less soluble phases, as dissolution of the more soluble material eventually causes its removal. However, the persistence of high magnesian calcites in sediments for long periods of time indicates that this process does not involve a large amount of mass transfer under normal marine conditions. 

Steps 2-4 were carried out in a vacuum reactor consecutively. Thus, the plasma reactor follows the cycle (1) pump down from ambient environment (2) O2 plasma (3) TMS plasma (4) HFE plasma (5) exposure to ambient air. The sequences of plasma processes are O2/TMS, TMS/HFE, and HFE/O2, or can be expressed -(02/TMS/HFE/)-. 

The plasma deposition step when the anode assembly was removed in flow system is designated by the process code Tfs. In the plasma deposition in a closed reactor system, the reactor chamber was first pumped down to less than 1 mtorr. The reactor chamber was then isolated from the pumping system by closing the main valve located in between. TMS gas, controlled by an MKS mass flow meter (model 247C), was then fed into the reactor. After the system pressure reached a preset point, TMS gas feeding was stopped and DC power was applied to initiate the glow... 

Over 80 percent of the world s production of sulfur is mined in Louisiana and Texas by a very clever method, the Frasch process. The sulfur, mixed with limestone, occurs at depths of about one thousand feet, under strata of sand, clay, and rock. A boring is made to the deposit, and four concentric pipes are sunk (Fig. 17-3). Superheated water (155°) under pressure is pumped down the two outer pipes. This melts the sulfur, which collects in a pool around the open end. Air is forced down the innermost pipe, and a bubbly froth of air, sulfur, and water rises through the space between the innermost pipe and the next one. This mixture is allowed to flow into a very large wooden vat, where the sulfur hardens as a product 99.5% pure. 

Figure 24-2 The Frasch process for mining sulfur. Three concentric pipes are used. Water at about 170°C and a pressure of 100 Ib/in (7 kg/cm ) is forced down the outermost pipe to melt the sulfur. Hot compressed air is pumped down the innermost pipe. It mixes with the molten sulfur to form a froth, which rises through the third pipe.

The terms EOR and lOR should refer to reservoir processes. Any practices that are independent of the recovery process itself should not be grouped into either EOR or lOR. Such practices include reservoir characterization, reservoir simulation, use of hardware and equipment (pumps, down-hole separators, etc.), use of special well types (horizontal wells, multilaterals, smart wells, etc.), improved reservoir management, infill drilling, and so on. Oil here means hydrocarbon, including oil and natural gas. 

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