Piping arrangements drums

Horizontal blowdown drum/catch tank This type of drum, shown in Fig. 23-49, combines both the vapor-liquid separation and holdup functions in one vessel. Horizontal arums are commonly used where space is plentiful. The two-phase mixture usually enters at one end, and the vapor exits at the other end. To overcome reentrainment of liquid droplets, due to high inlet velocities, various devices and piping arrangements are used to provide a more uniform distribution of vapor-liquid mixtures into the separator, as shown in Fig. 23-50. For two-phase streams with very high vapor flow rates, inlets may be provided at each end, with the vapor outlet at the center of the drum, thus minimizing vapor velocities at the inlet and aiding vapor-liquid separation. 

If required, piping at horizontal freestanding drums should be supported from the shell of the drum, the platform steel, or the concrete piers supporting the drum. Piping associated with drums located within structures should be supported from the struaural steel. Exhibit 5-24 shows tjpical pipe supports at a horizontal drum, and Exhibit 5-25 shows a typical pump suaion arrangement... 

All drum filters (except the single-compartment filter) utilize a rotary-valve arrangement in the drum-axis support trunnion to facih-tate removal of filtrate and wash hquid and to allow introduction of air or gas for cake blowback if needed. The valve controls the relative duration of each cycle as well as providing dead portions of the cycle through the use of bridge blocks. A typical valve design is shown in Fig. 18-121. Internal piping manifolds connect the valve with various sections of the drum. 

Piping to Burners - First and second stage piping and headers, as well as the burner lines themselves, are sized to minimize pressure drop and velocity effects. Thus, maldistribution of flow to the burners will be minimized. The burner lines are fabricated from standard 1(X) mm pipe, and are arranged in a split grid layout with distribution headers and split feed lines on opposite sides, for both first and second stage burners. First and second stage headers must be sloped so that any condensate will drain back to the seal drums. However, the burner lines must be accurately installed in a horizontal plane. 

Figure 3.15a. An arrangement similar to a conventional water-tube boiler. Steam is generated in cooling pipes within the reactor and separated in a steam drum. 

Process lines (a) which interconnect nozzles on process equipment more than 20 feet apart (closer process equipment can be directly connected by pipe lines) (b) product lines which run from vessels, exchangers or more often from pumps to the unit limits, to storage or header arrangement outside the plant (c) crude or other charge lines which enter the unit and usually run in the yard before connecting to exchangers, furnaces or to other process equipment, e.g., holding drums or booster pumps. 

Erratic distillation lower operation may be due to the uneven flow of a vapor-liquid mixture in a vertical run of pipe. An example of such an arrangement is the reflux drum-condenser combination pictured in Figisre 18-6. 

The Control Valve The other end ofthe filtrate pipe discharges after a 90 bend into the control valve faceplate, arranged parallel to the face of the drum. The so-called control plate is fixed to the control valve and forms the counterpiece to the faceplate. Various filtrate pipe sections are connected through apertures in the control plate. These apertures control the filter cycle inasmuch as, according to its position, the cell is evacuated by the vacuum connection, blocked or blown out with... 

When specified, steam drums and deaerators are usually furnished as a proprietary item. Layout is limited to confirmation of nozzle and support locations to suit piping and structural configurations and platforming for operator and maintenance access. Exhibit 5-3 illustrates a typical deaerator arrangement. 

Relief valves are usually furnished as part of the reactor piping. system and should be located in accordance with the arrangements shown in Chapters 5 (Drums) and 10 (Towers). 

The CUSH code has been developed to provide a complete representation of a primary circuit containing.several hundred channels with appropriate pumps, steam drums, headers, tall pipes and other features associated with a practical arrangement. Each channel is represented one-dimensionally and such aspects as the appropriate single- and two-phase pressure drops and coolant density distribution are calculated. A three-dimensional specification of the nuclear power distribution is required as input to CUSH. Specifications of the feed-water flow for a given steam output are also needed to determine the sub-cooling at channel entry and may be derived from the JAVAN complete steam plant model. 

---