Valves flapper

No trickle or flapper valves are used on the first stage. The riser cyclone diplegs terminate with a splash plate (Figure 9-4A). The upper reactor cyclone diplegs use conventional trickle valves. Sealing the upper reactor cyclone diplegs with about two feet of catalyst provides... 

Flapper Valve, Trickle Valve, or Check Valve is often attached to the end... 

B. Troubleshooting and Mounting a Mechanical Pump, it will be noted in Fig. 6.2 that gas from a rotary pump is exhausted through an immersed flapper valve. For this valve to make a good seal it must be covered with oil. One common cause of the loss of ultimate vacuum performance in these types of pumps is a low oil level, and this should be the first item to be checked when a pump is not performing well. A telltale sign of low oil is a change in the sound of the pump. 

Preheater. Figure 2 is a schematic of the preheat section. Ground raw shale is allowed to slide into or is pneumatically transported (a minimal volume flow) into the lower part of the preheater. A standpipe of shale serves as a resistance seal to purging gas and allows the preheater to be pressurized by transporting gas. Although a slide valve near the bottom of the standpipe should provide adequate flow control for the shale, a flapper valve, screw feeder, or rotary lock may be considered as options. 

Figure 23.15 shows the flow diagram of one prototype pulse combustion dryer designed by Novadyne Ltd (Canada) (Kudra and Mujumdar, 1995, 2002 Kudra et al., 2003). In the flash dryer configuration, the unit consists of a pulse combustor, a pneumatic duct that extends from the tailpipe of the pulse combustor, and devices for materials feed and discharge. The pulse combustor uses a self-actuated flapper valve, and its operating frequency is about 70 Hz. The rated capacity of the combustor equal to 300 kW offers an evaporative capacity of about 275 kg/h of water. Wet particulate materials such as sawdust, hog fuel, corn fibers, or spent coffee grounds are injected directly into the tailpipe... 

Based on the manner in which fuel and air charge the combustion chamber, pulse combustors are divided into two general categories those with mechanical valves and those with aerodynamic valves (also called valveless combustors). Mechanical valves can be further divided into three types flapper valves, reed valves, and rotary valves. 

According to Kentfield (1993), a pulse combustor is a combustion-driven device with self-aspirating feature, and this effect is achieved as a consequence of the internal unsteady flow events. In contrast, a pulsed combustor is a device with cyclic but nonresonant combustion as dictated by wave events. Pulsed combustors usually operate at a much lower than natural frequency, often controlled by an ignition, fuel injection, or a valve sequence. Therefore, valveless or flapper valve combustors fall into category of pulse combustors while mechanically driven valves (e.g., rotary valve) used to control either air or fuel inflow, flue gas outflow, or both should be categorized as pulsed combustors, unless the operation of a mechanical valve is controlled by resonant phenomena in a feedback mode. Such a design is known as a frequency-tunable pulse combustor. 

An integrated mixer/valve with a cantilever-plate flapper valve allows for non-continuous mixing by diffusion [49]. The mixer/valve consists of two wafers (i) a lower silicon wafer with a cantilever-plate flapper valve and fluid ports and (ii) an upper glass wafer that contains the fluidic channel. Initially the sample flows down the channel. When it is time to mix a reagent with the sample, the reagent is injected into the sample stream, and the two mix diffusively in a few seconds. After the desired section of sample is prepared, the reagent is shut off and the mixed... 

The purpose of the matrix is to help you prioritize hazards for corrective aetion. The categorization of hazards is based on severity and likelihood. Some hazards may be very likely to occur but of very minor consequences. One example is the minute release of nitrogen gas from a flapper valve into a well-ventilated, open area. Even if release is frequent, the severity of the hazard is low because the quantities are so low. However, an explosion at a commercial nuclear power plant may be remote (but obviously not impossible, as demonstrated by Chernobyl, or the remote possibility of an earthquake creating a tsunami wave hits a nuclear power plant and causes a meltdown as demonstrated by the Fukushima Daiichi nuclear disaster), but the consequences are great. These two hazards must be treated differently. Engineers too often treat all hazards equally, either overreacting or underreacting to the risk. 

The schematic shows the major components of the system. Some of the principal components are the cryotank, a flapper valve, fluid lines, valves, relief valves, burst disks, electric switches, and bayonet couplers. 

Two event trees are shown to give an indication of the kind of information available to the engineer. Figures 14.5 and 14.6 are the event trees for operator error of leaving valve 5 open and the flapper valve, respectively. 

Figure 14.6 illustrates the results of a very high failure rate in the flapper valve. With the valve stuck open, an ice plug forms in the vent line, resulting in a very high risk at 143,000. The various other barriers lower the risk significantly. 

A Initiating event fast pressure rise flapper valve... 

East pressure rise due to flapper valve falls open... 

FIGURE 14.6 Flapper valve failure event tree. 

Though the flapper valve has not been discussed much, it too has a high failure rate and risk expectation number. In this case, the only courses of action are to either redesign the flapper valve to be more reliable or replace it with a more reliable valve. 

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