scope:

1.1 Introduction

The purpose of this monograph is to provide design guidance on gravity-type oil-water separators for use in petroleum refineries, to provide practical advice on solving operating problems and improving separator performance, and to present information on the performance of existing separators.

This monograph deals solely with gravity-type oil-water separators, that is, those that rely on differences in specific gravity to separate oil globules from a wastewater stream. Two types of oil-water separators are covered in this mono-graph:

a. The conventional, rectangular-channel unit.

b. The parallel-plate separator.

Historically, the design of conventional oil-water separators was based on criteria developed from a 3-year, API-funded research study initiated in 1948 at the Engineering Experiment Station at the University of Wisconsin [1]. Since then, numerous oil-water separators based on the API-developed design criteria have been designed and put into operation throughout the petroleum industry. The criteria were developed as voluntary guidelines for designing conventional oil-water separators. Many other separators based in part on the API-developed design criteria have been adapted for a variety of other industrial wastewater treatment applications.

This monograph retains pertinent information from Chapters 5 and 6 of the 1969 edition of the API Manual on Disposal of Refinery Wastes, Volume on Liquid Wastes, and incorporates the recent findings of a literature review and 1985 survey of refinery separators. Data from this survey of the design and operation of oil-water separators have been incorporated in this monograph.

Although the theory of oil-water separators is briefly discussed, the emphasis of this monograph is on practical guidance for those involved in the design or operation of oil-water separators.