Flow gas flows

For counter flow, gas flowing up a column through a falling shower film of liquid, Fair s correlation of collected data is to he used as a guide ... 

Packing height of composite foam reactor Recycle liquid volume (1) Gas-liquid flow Gas flow rate, liBRT ... 

Figure 1. Slurry reactors classified by the contacting pattern and mechanical devices (a) slurry (bubble) column (b) countercurrent column (c) co-current upflow (d) co-current downflow (e) stirred vessel (C) draft tube reactor (g) tray column (h) rotating disc or multi-agitated column reactor (i) three-phase spray column — liquid flow —> gas flow.

Any form of convection, of course, increases the value of Ks. In slurry operation with no liquid flow, gas flow induces convection. In an agitated slurry reactor, stirring causes convection. In a pulsating slurry reactor, pulsation of the slurry induces convection and in a three-phase fluidized bed, the movements of both gas and liquid phases cause convection. Any one or more modes of convection will increase the value of the solid-liquid mass-transfer coefficient. In broad terms, the convective liquid-solid mass-transfer coefficient is correlated by-two steady state theories. Here we briefly review and compare them. 

The software is completely in ANSI-C. Dynamic memory allocation and pointer technique are particularly important for the utilization of automatic grid adaptation and the coupling of different FE kernels. The code consists of several FE kernels, which assemble the matrix equations for the specific partial differential equations of a physico-chemical problem, e.g. saturated groundwater flow, gas flow, multiphase flow, tracer transport and reactive transport. These FE kernels may be connected to each other via internal interfaces (so-called models) and with the common libraries to simu-... 

DSMC Simulations of Nanoscale and Microscale Gas Flow Gas Flow in Nanochannels... 

Bubbly flow In bubbly flow, gas flows as small bubbles dispersed in the continuous wetting fluid. This flow pattern is observed at moderate velocities for low gas frictions, where coalescence is minimal. 

Gas-liquid mixtures are sometimes reacted in packed beds. The gas and the liquid usually flow cocurrently. Such trickle-bed reactors have the advantage that residence times of the liquid are shorter than in countercurrent operation. This can be useful in avoiding unwanted side reactions. 

The performance of fluidized-bed reactors is not approximated by either the well-stirred or plug-flow idealized models. The solid phase tends to be well-mixed, but the bubbles lead to the gas phase having a poorer performance than well mixed. Overall, the performance of a fluidized-bed reactor often lies somewhere between the well-stirred and plug-flow models. 

The most common alternative to distillation for the separation of low-molecular-weight materials is absorption. In absorption, a gas mixture is contacted with a liquid solvent which preferentially dissolves one or more components of the gas. Absorption processes often require an extraneous material to be introduced into the process to act as liquid solvent. If it is possible to use the materials already in the process, this should be done in preference to introducing an extraneous material for reasons already discussed. Liquid flow rate, temperature, and pressure are important variables to be set. 

It was noted earlier that dryers are quite difierent in character from both distillation and evaporation. However, heat is still taken in at a high temperature to be rejected in the dryer exhaust. The appropriate placement principle as applied to distillation columns and evaporators also applies to dryers. The plus/minus principle from Chap. 12 provides a general tool that can be used to understand the integration of dryers in the overall process context. If the designer has the freedom to manipulate drying temperature and gas flow rates, then these can be changed in accordance with the plus/minus principle in order to reduce overall utility costs. 

The column is swept continuously by a carrier gas such as helium, hydrogen, nitrogen or argon. The sample is injected into the head of the column where it is vaporized and picked up by the carrier gas. In packed columns, the injected volume is on the order of a microliter, whereas in a capillary column a flow divider (split) is installed at the head of the column and only a tiny fraction of the volume injected, about one per cent, is carried into the column. The different components migrate through the length of the column by a continuous succession of equilibria between the stationary and mobile phases. The components are held up by their attraction for the stationary phase and their vaporization temperatures. 

Gibbs free energy or Gibbs molar free energy molar flow of gas phase acceleration of gravity enthalpy, molar enthalpy, weight enthalpy Henry s constant Planck s constant height horsepower radiation intensity molar flux... 

A volatile oil contains a relatively large fraction of lighter and intermediate oomponents which vaporise easily. With a small drop in pressure below the bubble point, the relative amount of liquid to gas in the two-phase mixture drops rapidly, as shown in the phase diagram by the wide spacing of the iso-vol lines. At reservoir pressures below the bubble point, gas is released In the reservoir, and Is known as solution gas, since above the bubble point this gas was contained in solution. Some of this liberated gas will flow towards the producing wells, while some will remain in the reservoir and migrate towards the crest of the structure to form a secondary gas cap. 

When fluid flow in the reservoir is considered, it is necessary to estimate the viscosity of the fluid, since viscosity represents an internal resistance force to flow given a pressure drop across the fluid. Unlike liquids, when the temperature and pressure of a gas is increased the viscosity increases as the molecules move closer together and collide more frequently. 

Oil viscosity is an important parameter required in predicting the fluid flow, both in the reservoir and in surface facilities, since the viscosity is a determinant of the velocity with which the fluid will flow under a given pressure drop. Oil viscosity is significantly greater than that of gas (typically 0.2 to 50 cP compared to 0.01 to 0.05 cP under reservoir conditions). 

If, however, the reservoir pressure drops below the bubble point, then gas will be liberated in the reservoir. This liberated gas may flow either towards the producing wells under the hydrodynamic force imposed by the lower pressure at the well, or it may migrate... 

Surface sampling involves taking samples of the two phases (gas and liquid) flowing through the surface separators, and recombining the two fluids in an appropriate ratio such that the recombined sample is representative of the reservoir fluid. 

For direct measurement from core samples, the samples are mounted in a holder and gas is flowed through the core. The pressure drop across the core and the flowrate are measured. Providing the gas viscosity (ji) and sample dimensions are known the permeability can be calculated using the Darcy equation shown below. 

In the solution gas drive case, once production starts the reservoir pressure drops very quickly, especially above the bubble point, since the compressibility of the system is low. Consequently, the producing wells rapidly lose the potential to flow to surface, and not only is the plateau period short, but the decline is rapid. 

One of the major differences in fluid flow behaviour for gas fields compared to oil fields is the mobility difference between gas and oil or water. Recall the that mobility is an indicator of how fast fluid will flow through the reservoir, and is defined as... 

Permeability (k) is a rock property, while viscosity (fi) is a fluid property. A typical oil viscosity is 0.5 cP, while a typical gas viscosity is 0.01 cP, water being around 0.3 cP. For a given reservoir, gas is therefore around two orders of magnitude more mobile than oil or water. In a gas reservoir underlain by an aquifer, the gas is highly mobile compared to the water and flows readily to the producers, provided that the permeability in the reservoir is continuous. For this reason, production of gas with zero water cut is common, at least in the early stages of development when the perforations are distant from the gas-water contact. 

Introduction and Commercial Application Section 8.0 considered the dynamic behaviour in the reservoir, away from the influence of the wells. However, when the fluid flow comes under the influence of the pressure drop near the wellbore, the displacement may be altered by the local pressure distribution, giving rise to coning or cusping. These effects may encourage the production of unwanted fluids (e.g. water or gas instead of oil), and must be understood so that their negative input can be minimised. 

Routine production tests are performed, approximately once per month on each producing well, by diverting the production through the test separator on surface to measure the liquid flowrate, water cut, and gas production rate. The wellhead pressure (also called the flowing tubing head pressure, FTHP) is recorded at the time of the production test, and a plot of production rate against FTHP is made. The FTHP is also recorded continuously and used to estimate the well s production rate on a daily basis by reference to the FTHP vs production rate plot for the well. 

Gas lift systems aim at lightening the liquid column by injecting gas into it, essentially stimulating natural flow. A gas lift string contains a number of valves located along the string. These valves are only required to kick-off the lifting process under normal... 

To prepare gas for evacuation it is necessary to separate the gas and liquid phases and extract or inhibit any components in the gas which are likely to cause pipeline corrosion or blockage. Components which can cause difficulties are water vapour (corrosion, hydrates), heavy hydrocarbons (2-phase flow or wax deposition in pipelines), and contaminants such as carbon dioxide (corrosion) and hydrogen sulphide (corrosion, toxicity). In the case of associated gas, if there is no gas market, gas may have to be flared or re-injected. If significant volumes of associated gas are available it may be worthwhile to extract natural gas liquids (NGLs) before flaring or reinjection. Gas may also have to be treated for gas lifting or for use as a fuel. 

In such a plant the gas stream passes through a series of fractionating columns in which liquids are heated at the bottom and partly vaporised, and gases are cooled and condensed at the top of the column. Gas flows up the column and liquid flows down through the column, coming into close contact at trays in the column. Lighter components are stripped to the top and heavier products stripped to the bottom of the tower. 

Keywords production decline, economic decline, infill drilling, bypassed oil, attic/cellar oil, production potential, coiled tubing, formation damage, cross-flow, side-track, enhanced oil recovery (EOR), steam injection, in-situ combustion, water alternating gas (WAG), debottlenecking, produced water treatment, well intervention, intermittent production, satellite development, host facility, extended reach development, extended reach drilling. 

The use of tracers enables efficient and reliable measurements of oil, gas and water flow in industrial process units and pipe line systems under production conditions thus fundamentally being non-destructive testing methods. Typical problems which can be efficiently assessed by tracer studies include ... 

Flow measurements using tracers are performed in all piping systems carrying oil, gas or water including separators, compressors, injector systems, and flares. Calibration of elsewhere difficult accessible flow meters is regularly performed by the tracer methods, which are based on international standards. Tracer flow measurements are also well suited for special purposes... 

Gas flaring in offshore installations and oil refineries represents a source of loss of energy making it important to operators and authorities to monitor the amounts of flared gas. In some countries the flare gas is subject to CO2 tax. Flow metering systems are installed on some but not all flare systems. 

The gaseous tracer method yields the equivalent piston flow linear velocity of the gas flow in the pipe without any constraints regarding flow regime under the conditions prevailing for flare gas flow. 

---