Pump, hydraulic system

Figure 9.18 provides an overview of the application envelope and the respective advantages and disadvantages of the various artificial lift techniques. As can be seen, only a few methods are suited for high rate environments gas lift, ESP s, and hydraulic systems. Beam pumps are generally unsuited to offshore applications because of the bulk of the required surface equipment. Whereas the vast majority of the world s artificially lifted strings are beam pumped, the majority of these are stripper wells producing less than 10 bpd. 

The bulk of hydrauhc fluids is specified and purchased on bid. Specifications and approval fists are issued by some manufacturers of hydraulic pumps and system components that require lubrication as well as power for control signal transmission. U.S. government military specifications for hydraulic fluids are fisted ia Table 12, and ASTM tests that are applicable to hydraulic fluids iaclude the foUowiag ... 

Relief Yalve normally selected for liquid relief service such as hydraulic systems, fire and liquid pumps, marine services, liquefied gases, and other total liquid applications. The valve characteristically opens on overpressure to relieve its rated capacity, and then reseats. 

In nearly all mechanical power applications in the oil and gas industry it is necessary to transmit the power generated by a prime mover to an operation (e.g., drawworks of a drilling rig, or a production pumping system). The transmission of rotary power to such operation elements is carried out by a power transmission system. Mechanical power transmission is typically carried out by power betting systems, chain systems, gear systems and by hydraulic systems, or some combination of these three [1,5]. 

Fluid power encompasses most applications that use liquids or gases to transmit power in the form of mechanical work, pressure and/or volume in a system. This definition includes all systems that rely on pumps or compressors to transmit specific volumes and pressures of liquids or gases within a closed system. The complexity of these systems range from a simple centrifugal pump used to remove casual water from a basement to complex airplane control systems that rely on high-pressure hydraulic systems. 

This is the energy source for hydraulic systems. It converts electrical energy into dynamic, hydraulic pressure. In almost all cases, hydraulic systems utilize positive displacement pumps as their primary power source. These are broken down into two primary sub-classifications constant-volume or variable-volume. In the former, the pumps are designed to deliver a fixed output (i.e. both volume and pressure) of hydraulic fluid. In the later, the pump delivers only the volume or pressure required for specific functions of the system or its components. 

Most hydraulic systems use a positive displacement pump to generate energy within the system. Unless the pressure is controlled, these pumps will generate excessive pressure that can cause catastrophic failure of system component. A relief valve is always installed downstream of the hydraulic pump to prevent excessive pressure and to provide a positive relief should a problem develop within the system. The relief valve is designed to open at a preset system pressure. When the valve opens, it diverts flow to the receiver tank or reservoir. 

A similar action takes place in a fluid power system in which the fluid takes the place of the projectile. For example, the pump in a hydraulic system imparts energy to the fluid, which overcomes the inertia of the fluid at rest and causes it to flow through the lines. The fluid flows against some type of actuator that is at rest. The fluid tends to continue flowing, overcomes the inertia of the actuator, and moves the actuator to do work. Friction uses up a portion of the energy as the fluid flows through the lines and components. 

The purpose of a hydraulic pump is to supply the flow of fluid required by a hydraulic system. The pump does not create system pressure. System pressure is created by a combination of the flow generated by the pump and the resistance to flow created by friction and restrictions within the system. 

As the pump provides flow, it transmits a force to the fluid. When the flow encounters resistance, this force is changed into pressure. Resistance to flow is the result of a restriction or obstruction in the flow path. This restriction is normally the work accomplished by the hydraulic system, but there can also be restrictions created by the lines, fittings or components within the system. Thus, the... 

A hydraulic system must have a reserve of fluid in addition to that contained in the pumps, actuators, pipes and other components of the system. This reserve fluid must be readily available to make up losses of fluid from the system, to make up for compression of fluid under pressure, and to compensate for the loss of volume as the fluid cools. This extra fluid is contained in a tank usually called a reservoir. A reservoir may sometimes be referred to as a sump tank, service tank, operating tank, supply tank or base tank. 

Strainers are used primarily to catch only very large particles and will be found in applications where this type of protection is required. Most hydraulic systems have a strainer in the reservoir at the inlet to the suction line of the pump. A strainer is used in lieu of a filter to reduce its chance of being clogged and starving the pump. However, since this strainer is located in the reservoir, its... 

Main system relief valves are generally installed between the pump or pressure source and the first system isolation valve. The valve must be large enough to allow the full output of the hydraulic pump to be delivered back to the reservoir. This design feature, called a full-flow bypass, is essential for all hydraulic systems. The location... 

Pressure regulators, often referred to as unloading valves, are used in fluid power systems to regulate pressure. In hydraulic systems, the pressure regulator is used to unload the pump and to maintain or regulate system pressure at the desired values. 

All hydraulic systems do not require pressure regulators. The open-center system does not require a pressure regulator. Many systems are equipped with variable-displacement pumps, which contain a pressureregulating device. 

Over the years the performance standards of hydraulic equipment have risen. Whereas a pressure of about 1000 psi used to be adequate for industrial hydraulic systems, nowadays systems operating with pressures of 2000-3500psi are common. Pressures above 5000psi are to be found in applications such as large presses for which suitable high-pressure pumps have been developed. Additionally, systems have to provide increased power densities, more accurate response, better reliability and increased safety. Their use in numerically controlled machine tools and other advanced control systems creates the need for enhanced filtration. Full flow filters as fine as 1-10 micron retention capabilities are now to be found in many hydraulic systems. 

With the trend toward higher pressures in hydraulic systems, the loads on unbalanced pump and motor components become greater and this, coupled with the need for closer fits to contain the higher pressures, can introduce acute lubrication problems. Pumps, one of the main centers of wear, can be made smaller if they can run at higher speeds or higher pressures, but this is only possible with adequate lubrication. For this reason, a fluid with good lubrication properties is used so that hydraulics is now almost synonymous with oil hydraulics in general industrial applications. Mineral oils are inexpensive and readily obtainable while their viscosity can be matched to a particular job. 

Probably the most important single property of hydraulic oil is its viscosity. The most suitable viscosity for a hydraulic system is determined by the needs of the pump and the circuit too low a viscosity induces back-leakage and lowers the pumping efficiency while too high a viscosity can cause overheating, pump starvation and possibly cavitation. 

The term passive interception is used to describe recovery systems that rely upon natural groundwater flow to deliver free-phase NAPLs to the collection facility without the addition of external energy (such as pumping). These systems often include linear interception-type systems such as trenches (or French drains), subsurface dams ( funnel-and-gate structures), combined hydraulic underflow with skimming, and density skimming units. 

Setting up an effective pumping recovery system requires a thorough understanding of subsurface conditions, especially the hydraulic conductivity, storativity, variations in vertical and horizontal geologic conditions, regional hydraulic gradient,... 

Consider the isothermal hydraulic system sketched below. A slightly compressible polymer liquid is pumped by a constant-speed, positive displacement pump so that... 

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... 

Motor vehicles are among the most complex assemblies of mechanical and electronic devices in existence. A piece of fire apparatus is among the most complex of all motor vehicles with hydraulic systems, power systems, pumps, compressed air, and lighting systems, to name a few. Today, computers have taken over more and more of the work that had previously been done by mechanical devices. All of these systems operate in addition to the normal subsystems discussed next. 

Brake, hydraulic, and recoil-cylinder fluids fall in much the same field of operating conditions. These are employed in systems in which operating units are exposed to low temperatures, and in practically all cases the connecting tubing lines are so exposed. Temperatures are not likely to go very high, but for aviation, temperatures as low as —70° F. may be frequent. Practically all brake systems and many hydraulic systems employ reciprocating units packed with synthetic rubbers. Hydraulic systems employ rotary pumps and often rotary motors these cannot be soft packed but are only capillary-sealed—i.e., close clearances. These pumps and motors drop in volumetric efficiency as viscosity falls. 

The earlier brake fluids of such materials as castor oil, glycerols, and alcohols could not meet the requirements of wide temperature range if the liquid was low enough in viscosity at the low temperature, it was too thin at the high for the pumps to operate motors at speed. If high enough in viscosity at the upper temperature, it was cheese at the low. Operators found that out in Arctic maneuvers, by way of broken shock absorber arms, burst brake and hydraulic system tubing, and sheared pump shafts. 

Nuclear Boiler Assembly. This assembly consists of the equipment and instrumentation necessary to produce, contain, and control the steam required by the turbine-generator. The principal components of the nuclear boiler are (1) reactor vessel and internals—reactor pressure vessel, jet pumps for reactor water circulation, steam separators and dryers, and core support structure (2) reactor water recirculation system—pumps, valves, and piping used in providing and controlling core flow (3) main steam lines—main steam safety and relief valves, piping, and pipe supports from reactor pressure vessel up to and including the isolation valves outside of the primary containment barrier (4) control rod drive system—control rods, control rod drive mechanisms and hydraulic system for insertion and withdrawal of the control rods and (5) nuclear fuel and in-core instrumentation,... 

The demands of this hydraulic system are best satisfied by the use of a single-stage centrifugal pump. These pumps are widely used throughout the chemical processing industry and offer several key advantages over other types as listed below ... 

Oligoethylsiloxanes and products based on them are as a rule transparent colourless nontoxic liquids. They can be used at operating temperatures ranging from -60-70° C to +180° C. The applications of these liquids are quite varied. They are used as coolants and heat carriers in hydraulic systems, as liquids for diffusion pumps, damping liquids and bodies for instrument oils and lubricants. 

On the human scale it is possible to copy this behaviour with pistons and hydraulic systems but can this be mimicked on the nanoscale If it can, then therein lies the potential to manufacture molecular scale pumps that could be incorporated into nanoscale devices. Furthermore if the contraction and expansion cycle could be linked to an external signal, such as the change in chemical environment associated with diseased tissue or tumour, the pump could form the basis of an in vivo drug delivery system that identified and treated diseases before they became manifest to a medical practitioner. 

The design diagram of the hydraulic system is presented in Figure 13. The pressure generated by the pump pmov (2 MPa) and characteristics of branches (pipe lengths and diameters, coefficients of resistances 7,) are given. 

It may be helpful to express the change of viscosity of a silicone oil in a different manner. If we compare a typical silicone oil with a standard hydrocarbon oil of viscosity index 100, the two having the same viscosity at 100° F., we find that after cooling to —35° F. the silicone oil has seven times the viscosity it had, whereas the hydrocarbon oil has increased 1,800-fold in viscosity. This relative constancy of viscosity of the silicone oil makes it particularly suitable for use as a fluid in hydraulic systems for the transmission of power. Silicone oils do not react with the common metals of construction, and they are so inert that even at 300° F. they do not discolor r become acid or form sludge. They are satisfactory lubricants in hydraulic pumps and in any other device where conditions of hydrodynamic lubrication prevail. When used as lubricants, methyl silicone oils do not suffer loss of viscosity through shear breakdown under continuous load at high speed. 

Figure 34 Freeze-drying plant condenser and shelves cooled with LN2. Clean-in-place system in chamber and condenser. 1, LN2 inlet to condenser and heat exchanger 2, N2 outlet from the condenser and heat exchanger 3, heat exchanger for the brine in shelves 4, brine to and from shelves 5, pressure plate for stoppering of vials 6, piston rod with bellows 7, hydraulic piston for 5 and 6 8, hydraulically operated valve 9, hydraulic system 10 and 13, water and steam inlet 11, pumping system 12, water outlet. (AMSCO Finn-Aqua GmbH, D-50354 Hiirth, Germany.)...

The rate of addition of solid fuel is controlled from the metering bin. A hydraulic system drives the metering bin conveyor. When the metering bin conveyor is stationary the electrically driven pump on the hydraulic power unit recirculates the hydraulic fluid to the reservoir. To start the metering bin conveyor a solenoid valve is opened allowing hydraulic fluid to turn the hydraulic motor. The flow and pressure of fluid to the hydraulic motor and ultimately the conveyor speed is controlled by a 12 position regulator valve on the hydraulic power unit. 

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