Valve Magazine - Fall 2011

The beaches and vast expanse of the southern California coast serve as a drawing card both for recreation and residency. Yet while the sound of the ocean can prove refreshing and soothing, excessive noise from businesses, traffic, construction and industrial operations can disrupt and impact the quality of a community.

Such is the case today with a heavily populated, coastal California town that constantly strives to reduce noise and its impact within its urban environment. The city has a noise ordinance that establishes exterior noise standards by land use. The ordinance regulates a variety of noise generators, with a focus on commercial and heavy industrial operations.

One of the operations that is a source of problems is a major “in-town” refinery. However, the refinery constantly works to reduce its disturbances. In a recent case, they pinpointed and removed a noisy valve.

THE REFINERY

When founded over 90 years ago, the refinery was distant from heavily populated areas. Today, however, the refinery complex is tightly surrounded by areas consisting of industrial, commercially-zoned, recreational and residential properties.

Land use to the north of the refinery
is primarily residential mixed with some
commercial and light industrial zoning.
Heavy industrial operations with a small
parcel of commercial and multiple-fam-
ily residences dominate the west side of
the refinery, while to the east is a golf
course along with light commercial and
heavy industrial zones. The noise prob-
lem was most prevalent, however, at the
southern length of the refinery, which
borders single-family residences, sepa-
rated from refining processes only by
the width of a four-lane avenue.

THE REFINING PROCESS IN A NUTSHELL To understand the source of the noise, it is helpful to review the refining process itself. This particular refinery receives crude oil both from a marine terminal and by conventional pipeline. The oil is heated and processed in the crude unit for primary distillation and separation into various components. It is processed first in the crude distillation tower where the oil is fractionated into the following streams:

; Liquid and non-liquid petroleum gas products, such as fuel gas, propane and butane.

; Light liquid products (naphtha), which are further upgraded in the naphtha hydrotreater and platformer for subsequent blending into gasoline.

VALVE NOISE
BROADBAND VS. TONAL
In general, valves in refineries pro-
duce two types of noises. They are:

; Broadband—Typically, noise generated by valves and piping components is broadband. That means human ears can hear the noise, but it is difficult to distinguish between sources.

; Tonal—Valves can also generate tones, but these situations are rare. Tones drive the overall sound pressure level, and therefore the human ear perceives them as being louder than the same overall level from a broadband source.

Tones are typically generated
by a resonance, which can be
either mechanical or acoustical in
nature.

; Middle distillates (kerosene and diesel), which are produced from the middle of the distillation tower. The kerosene goes to either jet fuel blending, the distillate hydrotreater for ultra-low sulphur diesel (ULSD) production or No. 6 fuel blending. The diesel goes to the distillate hydrotreater for ULSD production.

; The material remaining in the bottom of the crude distillation tower (the material is called atmospheric tower bottoms or ATB) is sent to the vacuum tower for further separation.