Mod 30ML User manual

MOD 30ML Demonstration Guide
INDUSTRY: Water / Waste Treatment
Water.DOC 11/8/99 Filter Backwash Demonstration
Filter Backwash Control
Introduction
Waste water treatment is one of the most common applications found in many industries. It involves two
stages of purification of waste water: Primary waste treatment, which is first treatment and involves
removal of floating and settleable solids which are contained in the waste water; and Secondary Waste
treatment, which uses biochemical reactions to remove suspended oils, settleable solids, soluble organics
which are present in water which has undergone the primary treatment.
The following demonstration involves primary waste treatment and shows the use of:
•integration of automatic sequential control and operator commands
•front panel display of filter and pump status
•operator notification and acknowledgement
•initiation of backwash seuqence through front panel
The Control System
The primary treatment is generally done with the help of a filter vessel. The raw waste water enters the
filter bed through a control valve, and the level is allowed to rise to near full capacity. All the floating and
settleable solids are filtered as the raw water passes through the filter bed. As the solids keep accumulating
on the filter, liquid flow is restricted and this causes an increase in the pressure of the filter. When this
pressure reaches a value either the filter manufacturer or the plant operator feels to be an allowable limit,
the filter must be cleaned. This process of cleaning the filter is known as filter backwash.
Fig.1. shows the primary treatment control system.
Raw Water
Air Pump
Air Valve
BW Pump
BW Water
Wash Water
Clean Water
Filter
Fig.1. Primary treatment Control System

Water.DOC 11/8/99 Filter Backwash Demonstration
The filter has three stages of operation:
Initialization:
This sets initial conditions. All the valves are closed, all motors are turned off and the tank level is at zero.
In Service:
The raw water is filled to 98% of the tank volume to provide adequate pressure for outgoing clean water.
The high level alarm opens the clean water valve, and level and flow are maintained at steady values. This
continues as long as the filter head pressure is within the allowable limits. All other valves remain closed
and pumps are off.
Backwash:
When the pressure crosses the limit, the backwash sequence is activated as follows:
1. The raw water valve is closed, and the clear water valve remains open till water level reaches zero.
2. When the level is zero, the air scour valve opens and air blower pump is turned on. Air is blown into
the filter, dislodging the solids which are removed through a drain valve.
3. Air blowing is then stopped and wash water is allowed in to fill the tank to 5% of the total level by
opening the wash water valve.
4. The drain valve is opened to let out dirty water and broken-up solids.
5. The wash water pump is then turned off, the level decreases to zero and backwash is complete.
Demonstration Guide
The MOD 30ML is performing the process simulation as well as the filter control and backwash sequence.
One analog input is used to simulate header pressure.
If the MOD 30ML demonstration kit is NOT used, the I/O should be disabled. To do this, use the TAG
key to scroll to the SIMULAT display and use the arrow keys to make sure it shows DISABLE. When the
I/O is disabled, all load changes can be made from their corresponding faceplate displays using the ramp
keys. The simulation will disregard any I/O that is connected to the instrument.
Load Changes
In order to create the situation necessary for backwash, the following disturbance can be introduced:
Pot #1 - header pressure
If the demonstration box is not used, the header pressure can be manipulated from the appropriate front
panel display using the ramp keys.
Alarms
Two alarms are configured to provide operator notification:
Loss of header pressure 91%
Backwash required > 98%
Operator Changes
The following operations may be done from the front panel display:
Put filter in service
Clear totalizer (clean water)
Manipulate header pressure
Initiate backwash sequence

Water.DOC 11/8/99 Filter Backwash Demonstration
Initial Conditions
Filter status - Initialize
Level - 0%
Header Pressure - 20%
Backwash pump, air scour pump, waste water pump OFF
1. Activity: Step through the tag displays (FILTER, PUMP STATUS, FLOWS, CW TOTAL,
HEAD PRESSURE). Press the SCROLL key on the FILTER, PUMP STATUS, and FLOWS
displays.
Look for: Filter status INITIALIZE
Level 0.0
All pumps OFF
Raw water and clear water flow 0 GMP
Header pressure 20%; bright segments indicate alarm trippoints for header
pressure
Clear water total 0 gallons
Benefit: The operator can view and manipulate all process values and discrete device status
associated with the process unit.
2. Activity: From the FILTER display, press the SCROLL key until OPC is displayed. Use the
UP/DN arrow keys to scroll to INSRVCE and press ENTER.
Look for: Scroll key function changes to entry function to confirm activity.
Bar graphs begin to indicate tank filling
Display indicates filter INSRVC
Activity: Press the scroll key to display level and total
Look for: Digital indication of increasing level and clear water total
Benefits: Sequences can be initiated from front panel, eliminating external pushbuttons
Keys may be assigned different functions according to operator requirements
Operator messages and sequence steps can be displayed on front panel
3. Activity: Use the TAG key to scroll to the FLOW PARMETERS display
Use the scroll key to view raw water flow and clear water flow in gallons per
minute
Look for: Raw water flow in gallons per minute (settles at 98%)
Clear water flow in gallons per minute (settles at 55%)
Benefits: Digital and graphical indication of process values for ease of operation

Water.DOC 11/8/99 Filter Backwash Demonstration
4 Activity: Use TAG key to scroll to HEAD PRESSURE display
Increase the header pressure to 91% using the ramp keys, or Pot #1 on the
demonstrator box
Look for: Bar graph indication of increasing header pressure
Flashing display and alarm light indicating alarm
Activity: Press the Alarm key
Look for: Alarm display with operator message, LOSS OF HD PRES
Benefit: Notification to operator that backwash requirement is imminent
5 Activity: Acknowledge the alarm and press the RET key to return to the header pressure
display
Raise the header pressure above 98% using the ramp keys or Pot #1 on the
simulator box
Press the alarm key when the alarm occurs
Look for: Alarm message, BAKWASH RQUIRED
Activity: Acknowledge the alarm and return to the tag display
Benefits: Message notification to operator through front panel, without requiring
additional external display
Operator required to acknowledge message
6 Activity: Press and hold the TAG key until *DEVICE* appears on the top line
Press the NXT (scroll) key until EVENTS appears on the bottom line
Press the DOWN arrow
Look for: BAKWASH RQUIRED on top line
PAD 3 on bottom line
Activity: Press the DOWN arrow
Look for: Current date on top line
Time of acknowledgement on second line
ACKED on bottom line
Benefit: Verification that message was received and acknowledged by operator
Activity: Press TAG key twice to return to main filter display

Water.DOC 11/8/99 Filter Backwash Demonstration
7 Activity: With OPC selected, use the UP/DN arrow keys to scroll to BCKWASH and
press ENTER
Look for: Level begins to decrease because raw water valve is closed
Low level alarm
Activity: Use TAG key to scroll to pump status displays
Look for: Air pump turns on for air scour
Air pump turns off and wash water pump turns on
Wash water pump turns OFF, backwash pump turns ON, and wastewater drains
BACKWASH COMPLETE message and alarm
Benefits: Comprehensive process information easily readably by operator
Discrete device status & description without external equipment
8 Activity: Acknowledge the BACKWASH COMPLETE and LEVEL LOW alarms
Press the TAG key to scroll to the CW TOT (clear water total) display
Look for: Total clear water in gallons; totalization has stopped during backwash
operation
Activity: Use UP/DN arrows to scroll to YES and press ENTER
Look for: Total is cleared
Benefits: Total flow available at front panel without external totalizer
Totalized value can be cleared from front panel
(Note: this could also be set up to clear based on a pre-determined count)
At the completion of backwash, the filter automatically returns to the INITIALIZE state. To repeat this
demonstration, return to the main filter display and select INSERVICE on the command line.