| |
Search this site |
| |
|
| |
Telemetry |
| |
|
| |
Telemetry Applications
|
| |
|
| |
News:
|
| |
|
| |
|
|
| Sewage
Treatment |
|
|
 Sewage treatment works process raw sewage to a point, where
in some cases the result is near drinkable water, or to a lesser degree
suitable for discharge to rivers, without risk of pollution. Control of such
works is local, with reporting to a central (remote) location normally into a
Management Information System (MIS).
There are many facets to sewage
treatment and apart from the entry to the works, gravity is used as the means
of creating flow from one area of the works to the next. Dependent on its
location, there may need to be a lift of the sewage on its arrival at the
works, to a high point, often by Archimedean Screw (see fig. 1) and from there
gravity takes over.
Local monitoring and control is normally
computer based to sift a whole variety of separate pieces of data collected by
outstations, each reporting back to the centrally located computer. Intelligent
Outstations (D7000 / Frontier range) and or PLC's can be introduced at points
where stand alone control can be beneficial, with the outstation reporting
again to the computer and also receiving changes to its set-points when
necessary.
As described earlier the Intelligent Outstation and or PLC
is a flexible unit that allows the programmer to write control functions into
it so that it can process data as a stand alone function without referring to
another source of control, it can, however, be influenced by telemetry, when it
is part of a network of non related functions, so that for instance, if the
inlet flow became higher than the works could handle for instance in a storm
condition, it would divert the flow into holding tanks until the inlet flow
reduces, when it would then let out the held volume and mix it with the normal
inlet flow in varying degrees until it had coped with the current
flows.
This form of control is known as SCADA (Supervisory Control and
Data Acquisition) and will control all of the many facets of a works made up of
Entry Elevation, Inlet Screens, Storm Water and Preliminary Treatment,
Balancing and Storm Tanks, Grit Removal, Sedimentation, Biological Processing,
Aeration and Treatment and Disposal of Sludge and Solids.
 These are a few of the individual process areas of a treatment
works which link together to form a continuous flow. The type of data that is
collected for simultaneous analysis are levels, flows, pressures, temperatures
as well as the running condition of the many pieces of plant machinery.
Sewage Treatment is a series of relatively simple control functions that add
together to form a complex whole like a jigsaw.
Dynamic Logic's Telview
/ Datacentre/2 Master Station SCADA packages cover all of the requirements of
works of any size and uses its own range of outstations for data collection
and, in some instances, simple on the spot or remote control from the central
computer.
Fig 2 Summarises the flows through the works. |
|
 |
|
|
|
|
|
|
