Boiler blowdown from

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 ... 

Ammonium Nitrate Plants - In ammonium nitrate plants, wet scrubbers can be considered for prill towers and the granulation plant. Particulate emissions of 0.5 kg/t of product for the prill tower and 0.25 kg/t of product for granulation should be the target. Similar loads for ammonia are appropriate. Other effluents that originate in a nitrogenous fertilizer complex include boiler blowdown, water treatment plant backwash, and cooling tower blowdown from the ammonia and nitric acid plants. 

The blowdown from the boiler(s) will be run to a flash-steam vessel mounted adjacent to the feed tank. Flash steam will be introduced into the feed tank through a dip pipe terminating in a distribution manifold. The drain from the flash vessel may then be taken to a residual blowdown heat exchanger. Any remaining heat is then transferred to the make-up water to the tank before the blowdown runs to drain. 

Blowdown from the boiler(s) should always be taken to either a blowdown sump or blowdown vessel before discharging into drains. Both should be adequately sized to give cooling by dilution and be fitted with vent pipes to dissipate pressure safely. The boiler(s) should have independent drain lines for the main manually operated blowdown valve and the drains from a continuous blowdown system. Where more than one boiler is connected to either system the line should be fitted with a check or secondary valve capable of being locked. 

When a boiler may not be shut down for maintenance of the level control chambers isolating valves can be fitted between the water-level control and the steam space. In this instance, the valves must be capable of being locked in the open position and the key retained by a responsible person. When these valves are closed during maintenance periods the boiler must be under manual attendance. Fitting of these valves should only be with the agreement of the insurance company responsible for the boiler. Drains from the water-level controls and level gauges should be collected at a manifold or sealed tundish before running to the blowdown vessel. 

Using a skimmer, the BD water is taken from close to the top surface of the BW, either from the side of the FT boiler shell or WT boiler top drum or from a top-mounted sparge pipe extending down 3 to 6 inches below the waterline (but above the top set of tubes in a FT boiler). Blowdown is provided on either a continuous blowdown or an intermittent blowdown basis. 

Generally, water is used in this plant to cool, leach, filter wash, scrub, heat, and washdown. The unreacted ore is slurred and sent, along with chromium and other impurities originally present in the ore, to the treatment plant. The boiler blowdown, which is sometimes contaminated with chromium escaping from the process area, adds to the volume of wastewater coming from the plant. The non-contact cooling water from the plant contains dissolved sulfate, chloride, and chromate thus it is sent to a wastewater treatment plant. The scrubber water may be used to slurry the ore or discharged. 

As discussed under boiler feedwater treatment, boiler blowdown is required to prevent the build up of solids in the boiler that would otherwise cause fouling and corrosion in the boiler. Carry over of solids from the boiler to the steam system via tiny water droplets should also be avoided. Total dissolved solids (TDS) and silica (SiC>2), as measured by the conductivity of water, are both important to be controlled in the boiler3. Dissolved solids carried over from the boiler will be a problem to all components of the steam system. Silica is a particular problem because of its damaging effect on steam turbines, particularly the low-pressure section of steam turbines where some condensation can occur. Blowdown... 

Qloss = heat losses from the stack, casing and boiler blowdown... 

Increasing condensate return for steam systems to reduce makeup water requirements, reduce aqueous waste from boiler feedwater treatment and boiler blowdown (see Chapter 23). 

Other sources of water for reuse may be from large industrial balance tanks and lakes, process save-all tanks, oxidation ponds, and receiving pits for boiler blowdown, or ion-exchange regeneration effluents. 

The saturator makeup includes the water effluent from the distillation system, which eliminates any liquid effluents from the plant, except blowdown from boilers, saturator or cooling tower, which are small flows. 

The cleared ICB effluent is approximately 98 wt percent water, 0.8 wt percent sodium sulfate, 0.7 wt percent sodium chloride, and traces of agent impurities and degradation products (PMACWA, 2006). The WRS and the brine reduction system (BRS) reclaim water from the biotreatment system effluent and the blowdown from both the cooling tower and the steam boiler. In addition, some process water passes through an RO system to feed the steam boilers and munitions washout system the retentate is fed to the WRS. 

Cooling water, yard runoff, and boiler blowdown are excluded from definition of "process water."... 

Use of hot water blowdown from boiler to preheat incoming cold feed water Put blinds in gas ducts at inlet and exit of process units to conserve heat during plant shutdowns. 

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