Header system

In pipe distributors, the pressure drop requited for good gas distribution is 30% of the bed pressure drop for upward facing holes, but only 10% for downward facing ones. The pressure drop calculation and the recommended hole density are the same as for a perforated plate. To maintain good gas distribution within the header system, it is recommended the relation... 

AH vapors, including hotweH odors, are captured in a header system linked with the incineration air of a steam boiler or hot oil vaporizer. Drain seals avoid escape of odors from the sewer lines. This completely eliminates total reduced sulfur (TRS) emissions. The SO2 emissions are subject to local regulations. 

To handle the methane gas generated from the 42.5-acre site, an active interior gas collection system was installed as shown in Figure 11. The installation consisted of 42 recovery wells, a gas collection header system, condensate traps, blower station and a flare station. In addition, a methane monitoring system consisting of thirty-two 2-inch wells was installed around the site (U.S. EPA, 1987). 

Fatigue Failure - The combined discharge header system should be designed in accordance with the same considerations of potential piping fatigue failure as described below for closed discharge systems. 

Potential vibration problems of this type should be considered early in the design stage of the flare header system. The following screening criteria have been developed to assist the designer in recognizing services with potential vibration problems requiring further detail evaluation ... 

Closed Drain Header Systems for Flammable Liquids... 

Conventional relief valves should only be used where the discharge is routed independently to atmosphere, or if installed in a header system, the back-pressure build-up when the device is relieving must be kept below 10% of the set pressure so the set point is not significantly affected. The set point increases directly with back-pressure. 

Liquid seal drums Emergency vent streams are usually passed through a liquid seal, commonly water, before going to the flare stack. The liquid seal drum is usually located downstream of the knockout drum, and some vendors designs include them in the base of the flare stack. A liquid seal drum is used to maintain a positive pressure in the vent header system and upstream system. It also reduces the possibility of flame flashbacks, caused when air is inadvertently introduced into the flare system and the flame front pulls down into the stack it also acts as a mechanical damper on any explosive shock wave in the flare stack. Figure 23-58 is a schematic of a typical flare stack liquid seal drum, designed per API RP 521 criteria. 

All waste hydrocarbon gases (vents, relief valves, and blowdowns) should be routed to a flare or returned to the process through a closed header system. Release of vapors to atmosphere may produce a vapor cloud, and even through the release may be remote from the facility it may drift or the effects of ignition (i.e., blast overpressure) of the cloud will be felt at the facility. 

In order to handle hot chlorine gas from the cells a header system has been developed (Fig. 23.16) whereby stray current dumpers take care of the brine condensates that would otherwise result in damage. 

Even though the reaction force due to the exhaust jet to atmosphere is significantly greater than the change in momentum component, the API makes no distinction for SRVs discharging into a closed header system compared with discharging through a tail pipe or direct to atmosphere. 

Many valves and other equipment are connected to the same header system, so the pressure in this system can vary greatly, causing a permanent variable superimposed backpressure on the SRV, as described in Section 3.4. This variable backpressure will act directly on the top of the disc of a conventional SRV and add itself to the original set point (opening pressure) of the SRV. 

Header systems with manual or automatic dispensing valves have been designed to carry adhesives and sealants over long distances within the plant. Distances of as much as 300 ft are not uncommon with drops at points of application. Figure 17.7 shows a modular header system. Adhesives and sealants are nearly ideal materials for application by robots. Robotic application is commonly used in the automobile industry to increase quality and to reduce labor and material cost.7,8... 

The feed is desulfurized and mixed with process steam before entering the steam reformer. This steam reformer is a top-fired box type furnace with a cold outlet header system developed by Krupp Uhde. The reforming reaction occurs over a nickel catalyst. Outlet reformed gas is a mixture of H2, CO, C02 and residual methane. It... 

The Hooker-Uhde Monopolar Membrane electrolyzer is shown in Figure 19. The active electrode surface of the HUMM electrolyzer is 1.7 m per cell element. The cell elements consist of anode frames of titanium and cathode frames of steel. Anode-cathode gap is approximately 3 mm. A separate frame is provided for holding the membrane. The electrode block rests on a support structure that serves as the header system for electrolyte and electrolysis products. Peformance of this electrolyzer is reported to be 2750 KWH/M ton NaOH at 35% caustic soda and 95% current efficiency at 3 KA/M current density (65). 

Figure 4. Sulfur spray header system and spray nozzle details...

A slightly more automated method would be to feed the water to each rotameter from a pressure-controlled header system (Fig. 11.46). The pressure would be measured with a diaphragm seal connected to a transmitter with a filled capillaiy. llie control valve would be a fail-open globe or V-ball valve with equal percentage characteristic. The controller would be reverse-acting with proportional and integral action. This arrangement allows... 

Preparation for Cell Room Energization. Electrolyzers are isolated from header systems by blanks or slip plates during commissioning of the brine, caustic, chlorine, and hydrogen systems. Immediately before startup of those systems, all blank plates should be removed, leaving only valves closed where it is appropriate to isolate electrolyzers. There should be a record of all blank plates and slip-plates and their locations. This will help to ensure that all are removed before startup. 

Three methods are used to remove condensate, primarily for calandria steam chests. Tracing and steam header systems can usually be handled by the first of these methods. The three methods are ... 

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