Trickle valves

Trickle valves Manual or automatic valves or openings that allow a given quantity of air or other gas to pass from one space to another. 

Figure 1-8. Typical trickle valve (courtesy of Emtrol Corporation).

Trickle valves are either stuck closed or open, possibly due to the hinges being warped or bound. Warpage could be due to... 

Trickle valves have fallen off due to inadequate bracing and/or high superficial gas velocity in the regenerator. 

High catalyst level can prevent the primary cyclones from draining or prevent the trickle valves from operating properly. 

Trickle Valves ara either stuck closed or opened Trickle Valves are either warped or eroded Trickle Valves have fallen off Holes in the Diplegs Cracks in the Plenum Diplegs diameter either "too small or too large ... 

ABB Lummus s RTD consists of a two-stage reactor cyclone system (see Figure 9-2). The riser cyclones (the first stage) are hard-piped to the riser. Attached to the end of each riser cyclone dipleg is a conventional trickle valve as shown in Figure 9-3. Each trickle valve has a small opening to prevent catalyst defluidization, which can be a problem, especially during start-ups. 

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... 

EROSION RESISTANT DIPLEQS -AND TRICKLE VALVES -MINIMIZE OAS IfPYLOW INTO DiPLfiOS -SMOOTH OIPLEQ LEVELS MFROVE EPRCtENCY... 

The dumping mode of trickle valve operation occurs at low solids velocities, low aeration and/or leakage rates, low cyclone pressure drops, and low valve torques. These are the opposite of what causes the more desirable eonstant triekling flow. This mode of flow causes more frequent bloekage of solids and may cause exeessive wear in the upper part of the dipleg discharge. 

Trickle valve diplegs in commerdal units often exhibit erosion in the upper part of the dipleg and/ or in the upper part of the flapper. This is beeause gas leakage is preferentially through the upper part of the trickle valve (Fig. 27A). The relatively high leakage... 

Figure 27 Trickle valve leakage and erosion prevention.

Bristow TC, Shingles T. Cyclone dipleg and trickle valve operation. In Grace JR, Shemilt LW, Bergougnou MA, eds. Fluidization VI, 1989, pp 161-168. 

Broodryk and Shingles (1995) studied parallel cyclone operation with cyclones in the freeboard above a turbulent fluidized bed. They found that too low an overall pressure drop (caused by inlet gas velocities of less than about 15 m/s) resulted in preferential flow of gas through two of their three cyclones. They also found that poor trickle valve design and/or operation could induce an imbalance in the gas flow into the cyclones. When preferential gas flow occurred, it resulted in significant solids carryover and reduced cyclone efficiency. 

We have seen that, for a high conversion process, tracer experimentation on cold mock-ups give the minimum diameter a pilot plant can have. Other considerations dictate its final size. It has to be big enough to allow a fair replication of the grid and of the heat exchanger of the commercial plant, A man has to be able to squeeze himself into the vessel at times to repair various internals, e,g, trickle valves on cyclone diplegs. Sixty... 

Fig. 11.1.4. Flapper-type underflow sealing valves featuring free-swinging hinged seal plates. Ducon type CA Trickle Valve (left) and type FA Trickle Valve (right). Courtesy Ducon Technologies Inc.

TEEPOL—Royal Dutch/Shell Group Trickle Valve—Ducon Technologies Inc. 

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