- Eliminate Telescopic Valve Sludge removal
Eliminate Telescopic Valve Sludge removal
By: Mukwonago Staff
Removing sludge from a clarifier through a telescopic valve often results in thin sludge removal and dilute solids in a digester.
We were going to modify the rectangular clarifiers to cosolidate sludge in 2 sumps, instead of the original 4. After giving the issue time, we opted to install automatic valves that allow us to bypass the telescopic valve and use the sludge pump to pull sludge from each sump. The computer control allows us to withdraw the sludge on a schedule (we\'re using 6 cycles) and we can adjust the time each valve remains open.
The project is allowing us to feed the digester on a more regular basis (single shift operation), reducing water to the digester (saving on heating costs), and is expected to reduce the weekend overtime.
- Adding a Drain to the Belt Press Sludge Feed Line
Adding a Drain to the Belt Press Sludge Feed Line
By: Matt Kube
When we begin a press run, the first slug of sludge is not properly conditioned for dewatering. It can take a couple minutes before polymer lines are purged and the proper balance of sludge and polymer is achieved.
If this initial slug of sludge is added directly to the press, it binds the belt and makes a mess. So we had the water department install saddle valves in each sludge feed line. By opening the valve on start-up we can "waste" the poorly conditioned sludge until the proper conditioning takes place.
It is also used during clean up to drain the feed line so small dribbles of sludge don't continue to fall on the belt.
- Drain/Flush Port on Sludge Heat Exchangers
Drain/Flush Port on Sludge Heat Exchangers
By: Roger Tarman
The small drains on our sludge heat exchangers are inadequate to drain or flush sludge from it. They are easily plugged by rags when draining and don't allow a large volume of water for back flushing. By welding a one-and-a-half inch pipe to the clean out port we can now use a higher volume of flushing water for back flushing. By quick coupling a small length of hose we can drain the heat exchanger by piping directly to the floor drain -- without making a mess when opening the port cover.
The inspection port cover can be easily removed to perform the drilling and welding in the shop so there is no out of position work.
- Drip Leg to Keep Condensate Out of Manometer
Drip Leg to Keep Condensate Out of Manometer
By: John Kaeppel
To prevent condensate from forming in the manometer, John added a small drip leg to the line that connects to it. Note that the line from the manometer to the leg slopes downward so condensate drips down into the drip leg. The valve at the bottom is used to drain the condensate.
- Pressure Washing Vivianite from Sludge Heat Exchangers
Pressure Washing Vivianite from Sludge Heat Exchangers
By: Waukesha Staff
Vivianite builds up on our digester lines, valves, and heat exchangers. To keep heat exchanger efficiency up on our sludge heater, we pressure wash the tubes once a year. The pressure washer wand is extended with a 1/4 inch pipe with a 45 threaded onto the end. This directs the pressure washer stream on the tube walls.
To prevent the "cleanings" from propelling out the other end of the tubes and making a mess, we placed two 4 x 8 sheets of particle board at a 90 degree angle to each other using a 2 x 4 as a brace in the corner. A plastic tarp is placed around the ends to catch any pieces that blow by.
Though it's not pretty, this set-up really does the trick. Without it vivianite pieces would be blown everywhere.
The wand is inserted into the tubes and rotated on each pass to clean the entire inside circumference of the tube. Notice how there is a quick disconnect in the middle of the wand extension. This makes for easy storage and provides a means of turning the angled end of the wand.
If the vivianite is really stubborn, run the wand though from both ends.
- Routing Filtrate to Flush Sludge Squeezings
Routing Filtrate to Flush Sludge Squeezings
By: Ed Artymuik
There always seems to be a small amount of sludge that squeezes between the belts in the high pressure section of our belt press. Unfortunately, this sludge builds up in the drain collection pans. To flush this accumulation of sludge, some filtrate from the gravity section is diverted to this area.
This piping arrangement does cause the lower filtrate drain collection pan to overflow.
- Tube-In-Tube Thermophylic Digestion
Tube-In-Tube Thermophylic Digestion
By: Dean Falkner
There have been people interested in attempting thermophylic digestion. A key issue has been how to put enough heat into the digester to reach thermophylic operation, because most people believe that the highest water temperature one can safely use in a heat exchanger is 160-170 degrees F.
We approached Walker Process, a manufacturer of tube in tube heat exchangers. They cited the fact that the higher water temperatures can cause sludge glazing (loss of heat exchanger capability) if the sludge is heated to the higher temperatures in the heat exchanger. However, there's not enough hot water in a tube in tube heat exchanger to overheat the sludge. Therefore, all one has to do is stop the water flow if sludge flows stop. I've been told that Chicago is running water temperatures approaching 200 degrees F for their thermophylic digester operation.
If you are thinking about thermophylic digestion, contact your heat exchanger manufacturer and get their input. You may have much more capability than you ever dreamed!
- Waste Gas Burner Automation
Waste Gas Burner Automation
By: Dean Falkner
The anaerobic digesters never produce the right amount of gas. The most critical issue is the fact that the conventional digester gas pressure reliefs are subject to freeze-up during the winter time with sub-zero temperatures.
The waste gas system can be easily automated to provide venting when necessary, actual burning of the gas at the waste gas burner, and avoiding of gas-loss at the pressure relief valves.
The components needed to achieve a successful operation include:
1. An intrinsically safe pressure transducer or intrinsically safe pressure switch.
2. A PLC capable of being programmed to open a valve and initiate an ignitor system. Ideally, it will try reignition every 10 minutes or so of burner operation. The program and input requirements is dependant on the type of unit selected for pressure monitoring (item 1). The output requirement must be consistant with the valve operator (item 3).
3. A suitable valve operator to open the gas wasting valve. We used a simple air-operated valve opener....requiring only control of the solenoid to do the job. It is a simple system that can significantly reduce the potential of major digester damage associated with relief valve freezing in sub-zero weather.
- Waste Gas Burnner Photo Cell Upgrade & Working Platform
Waste Gas Burnner Photo Cell Upgrade and Working Platform
By: Roger Tarman, Matt Kube, Ed Artymuik
In Wisconsin, state construction code requires a UV photocell for flame detection on waste gas burners. At Waukesha, the original set up literally burnt up in a matter of days. The flame would not only burn up the wires, but the liquid tight flex conduit. It was redesigned with special wire that had high temperature insulation and boiler insulation was packed around the UV photo sensing eye and the wires. Instead of using liquid tight flex conduit, a pipe was welded onto the UV flame detector enclosure to an appropriate distance from the flame.
To make it easier to do all this work a platform was made. This made it not only nicer to perform the work, but made it a safer operation also.