Tank Systems

For compressed storage of hydrogen, the gas is usually compressed to pressures between 200 and 350 bar though, more recently, storage pressures of 700 bar and even higher have been under trial. Such enormous pressures require consideration of questions regarding material choice, component dimensioning and safety. 

Hydrogen has a tendency to adsorb and dissociate at material surfaces, the atomic hydrogen then diffuses into the material and causes embrittlement and diffusion. Materials suitable for hydrogen applications are mainly austenitic stainless steel and aluminum alloys [12, 29]. 

With adequate material and dimensioning, gaseous hydrogen storage takes place in a closed system and thus hydrogen can be stored without loss for extended periods of time. 

Apart from storage in vessels, underground storage of large quantities of hydrogen in natural caverns has also been investigated [16]. 

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Laser-based profilometry systems have also been applied for nondestructive testing and measurement of both smooth-bore and rifled gun tubes. Working through Small Business Innovation Research program, the U.S. Army has developed laser-based profilometry systems for the inspection of the 120mm cannon used on the MI-Al Abrams main battle tank. Systems have also been built to measure the erosion of 25 mm and 155 mm rifled gun tubes. 

The resulting fault tree is shown in Figure 6, in which the top event is defined in terms of two intermediate events failure of the tank system or failure of the pumping system. Failure in either system would contribute to the overall system failure. The intermediate events are then further defined in terms of basic events. All of the basic events are related by AND gates because the overall system failure requires the failure of all of the individual components. Failures of the tanks and pumps are basic events because, without additional information, these events cannot be resolved any further. 

Knowledge-based systems typically use quaHtative methods rather than quantitative ones. For example, consider a simple tank system. The equation describing the flow rate of Hquid out of the tank is given below, where C is the orifice coefficient, d is the diameter of the orifice, and h is the height of Hquid in the tank. Based solely on the form of the equation, a human reasoner can infer that the flow rate F increases monotonically with the height b of Hquid in the tank. 

Second-Order Element Because of their linear nature, transfer functions can be combined in a straightforward manner. Consider the two tank system shown in Fig. 8-12. For tank 1, the transfer funcdion relating changes in/i to changes in can be obtained by combining two first order transfer functions to give ... 

McAllister gives the following equation for the vapor formed when filling a tank. This must be known when sizing the vapor piping for a manifolded expansion-roof tank system. 

The requirements above and in NFPA 30 must be properly applied after evaluation to ensure that they apply to the tank system concerned. The latest edition of NFPA 30 should be used as it is periodically updated. 

Continuous culture is not considered suitable for citric add production the requirement for a multi-tank system to separate growth and product formation would make the process uneconomic. 

The residence time distribution for a two-tank system is given by... 

When Equation 9 is used in Equation 8 along with the relationships for the residence time distributions one obtains the following dimensionless particle size distributions for one- and two-tank systems. 

Well-mixed tank systems (Fig. 2.18) are characterised by a first-order lag response. 

Figure 2.18. Simple continuous flow tank system.

Consider the necessity to extract a product which impedes a reaction in a continuous tank system. This can be accomplished with an integrated extraction unit, here a liquid-liquid extraction system. 

Figure 5.88. A pulse of tracer was simulated by setting k = 0 and setting = 0 for a duration of AT = 1. The residence time TAU in each tank was 20, or 160 for the entire 8-tank system.

The regulatory standards for leak detection in tank systems containing hazardous chemicals are more stringent than those for tanks containing petroleum motor fuels. Both above standards and those required in RCRA hazardous substances management should be met. 

Release Detection Approaches for Modern Tank Systems... 

Release detection is an important aspect of the management of USTs. U.S. EPA regulations required an upgrade of release detection during the 10-yr period between 1988 and 1998. The external or internal detection systems should be in compliance with the requirements for modern tank systems. 

There are three methods of release detection that are associated with modem tank systems.18,22 The first approach is to conduct an annual tank or line tightness test to detect small releases and to use more frequent monitoring by another method to detect large releases. All tank and line tightness tests must be performed at least once a year and must be able to detect leaks of 0.38 L/h (0.1 gal/h). In all cases where annual tightness tests are used, the regulation requires an additional form of leak detection in which tests on tanks are conducted at least monthly and those on pressurized lines at least hourly this ensures the detection of excessively large releases. For tanks, daily inventory records must be reconciled monthly, for pressurized lines, leaks of up to 11.4 L/h (3 gal/h) must be reliably detected. 

The third approach is to install an external monitoring system that can detect the presence of the stored chemical in or on the groundwater or in the backfill and soil surrounding the tank system. In many instances both internal and external methods are used in conjunction as a way to increase the liability of detection. 

New tank systems are also equipped with leak monitoring devices that take advantage of the double-walled construction. Leakage can be reported in real time and more accurately using these detection devices, which include water- or product-sensitive probes, or pressure detection devices if the space between the two walls is designed to remain under vacuum. 

It is more exposed to local building codes, which usually do not favor aboveground tank systems. 

U.S. EPA, Underground Storage Tanks, Cleaning Up Underground Storage Tank System Releases, U.S. EPA, Washington, March 2006. Available at http //www.epa.gov/OUST/overview.htm. 

U.S. EPA, Operating and Maintaining Underground Storage Tank Systems Practical Help and Checklists, EPA-510-B-05-002, U.S. EPA, Washington, September 2005. 

Two general methods have evolved. One uses a stirred tank system, while the other depends on the measurement of particle size or surface area change via particle counting or image analysis techniques. 

An alternative to the stirred tank system is a column-type device which provides for constant fluid flow through a powder bed. The mass transport process was shown to be primarily determined by the length and cross-sectional area of the cylinder and the fluid flow rate [36],... 

CONFLO 1, CONFLO 2 and CONFLO 3 - Continuous Flow Tank System... 

A power curve is a plot of the power function 4> or the power number Po against the Reynolds number for mixing ReM on log-log coordinates. Each geometrical configuration has its own power curve and since the plot involves dimensionless groups it is independent of tank size. Thus a power curve used to correlate power data in a 1 m3 tank system is also valid for a 1000 m3 tank system provided that both tank systems have the same geometrical configuration. 

Calculate the theoretical power for a six-blade flat blade turbine agitator with diameter DA = 3 m running at a speed of N = 0.2 rev/s in a tank system conforming to the standard tank configuration illustrated in Figure 5.5. The liquid in the tank has a dynamic viscosity p = 1.0Pas and a density of p = 1000 kg/m3. 

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