Sewers oily water

The area below the stack and windbreaker is paved with concrete, surrounded by a 200 mm curb, and graded to a central drain point from which a drain line is routed to a manhole in a vented section of the oily water sewer. The water inlet should be sealed and the manhole should be located at least 15 m from the windbreaker. 

The 300 mm water seal is maintained by the location of the overflows which discharge to the oily water sewer through the primary seal loop. The water... 

Common practice and a general guide is to prevent combustible vapors from transmitting from one process area to another process area, generally 15.2 meters (50 ft.) or more away. Usually unsealed receptacles, such as drain funnels, tundishes, drain boxes, are routed to the nearest local sealed catch basin and then into the oily water sewer main. The unsealed receptacles are only allowed in the same process area equipment where if vapors where released from an adjacent unsealed receptacle it would be "immaterial" due to the proximity to where the liquid is being drained and would normally emit vapors. 

In some cases a closed drainage system can be used which drains process components directly into the oily water sewer. This has the advantage of avoiding releases of vapors in any instance, but assurance must be obtained that back pressure from one drainage location will not backfeed liquids into another drain point when two valves are open simultaneously or other drainage valves can contain any backpressure on them from other drainage sources. 

A process oily water sewer system is a convenient location to direct oily wastes. The oily water system normally collects into a sump. If several lines connect into a common header, care should be taken to prevent backflow into another outlet source. In such cases use of an air gap, i.e., drainage in to a collection ftinnel has be advantageous. 

Oily water sewer (OWS), vents and drain funnels. 

Where drainage provisions are provided to the battery room, the fluid should first collect into a neutralizing tank before entering the oily water sewer system (OWS). 

In addition to a system for disposing of rain, fire, and wash-down water, many process units require special dedicated sewer systems (i.e., chemical and oily water sewers) for routine nonemergency drainage of process waste due to environmental, waste disposal, cross-contamination, or reactivity reasons. Chemical, process, or oily water sewers are usually not appropriate in capacity or purpose for use in drainage of large uncontrolled process spills, rain water, or fire water. 

Chemical, process, or oily water sewers are typically designed to receive drainage directly from tanks, vessels, pumps, equipment, and piping. Their... 

Process, chemical, or oily water sewer system branch and lateral lines should enter main lines through vapor-sealed and vented manholes. Branches and laterals in clean or storm water drainage systems may enter main lines without vapor seals if liquid-sealed catch basins are used on the inlets to these branches and laterals. 

The waste streams in most large plants can be classified under four basic sewer systems (1) Oily-water sewer, (2) acid (chemical) sewer, (3) storm-water sewer and (4) sanitary sewer. Typical sewer systems are shown in Figure 8-1. The design and operation of each type will be described in detail. 

On paved and unpaved surface areas adjacent to tanks, towers, exchangers, pumps and compressors where process waste spillage is likely to be considerable, drainage sho d be divirted to the oily-water sewer. Wash water heavily contaminated with hydrocarbons during turnaround or maintenance operations should be drained to the oily-water sewer. 

The oily-water sewer main should be run to the battery limit as a separate system and there connected to the oily-water trunk sewer which runs to an oil-water separator. 

The oily-water sewer flows to an oil-water separator for oil removal sediments are also removed in a sludge disposal chamber. Conventional chemical treatment will also be necessary. 

Diked or curbed areas at tank farm and storage locations will also require provisions for surface drainage and should be divided into suitable drainage areas. These drains should be run to the oily-water sewer main. 

The oily water sewer that also accommodates process condensates after desired pretreatment. 

The accidentally oily water sewer which is characterized by the addition of a storm basin. 

This system picks up drains around boilers and steam drums and is run as a separate system, preferably to the battery limit. It is permissible to tie into a sewer box in the oily water sewer system as long as it is located downstream from any sewer box that collects... 

Sewer boxes Used in oily water sewer systems, sewer boxes ... 

Sanitary sewer systems should be entirely segregated from oily water sewer systems. Similarly, process venting or blowdown systems should not be connected to the sewer system. 

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