Utility system blowdown

Utility System Blowdown. The generation of plant utilities also produces wastes that require proper treatment and disposal. Here we consider three categories ... 

The utility system also creates waste through products of combustion from boilers and furnaces and wastewater from water treatment, boiler blowdown, etc. Utility waste minimization is in general terms a question of ... 

Blowdown systems utilize a series of flash drums and condensers to separate the blowdown into its vapor and liquid components. The liquid is typically composed of mixtures of water and hydrocarbons containing sulfides, ammonia, and other contaminants, which are sent to the wastewater treatment plant. 

Wastewater streams from the utility functions include boiler and cooling tower blowdowns and waste brine and sludge produced by demineralizing and other water treatment systems. The quantity and quality of the wastewater streams depend on the design of the systems and the water source. These streams usually contain high dissolved and suspended solids concentrations and treatment chemicals from the boiler and cooling tower. The blowdown streams also have elevated temperatures. 

The earlier PSA units typically utilized 2,3, or 4 adsorber beds in a cyclic sequence in which one of the beds was always on an adsorption step while the other bed or beds were being regenerated. However, these systems were inherently inefficient for two reasons. First, the blowdown from adsorption pressure to the low waste pressure caused large losses of the desired product gas which was stored in the bed at high pressure. Second, some pure product gas was cycled to waste since it was used to purge a regenerating bed. 

The main arterial system of a plant is yard piping. It is here that long process lines are located interconnecting distant equipment and lines entering and leaving the units. Utility headers are located in the yard supplying steam, air, gas and water to process equipment. All relief and blowdown headers are located here. Often instrument lines and electrical supply conduits are also supported on the yard steel. 

Figure 11.1.1 illustrates six common industrial underflow or seal configurations. Most industrial cyclone systems utilize one of these seal designs or some variant thereof. The primary purpose of these underflow sealing devices is to isolate, more or less, the cyclone from the conditions that exist downstream of the sealing device. Without such a seal, either gas would blow out the bottom of the cyclone or it would flow up the cyclone. Neither of these conditions is normally desirable although a controlled amount of gas blowdown may be specified in some instances for solids conveying purposes. 

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