Ultrasonic level gauges are mostly used in water distribution metering tanks, return sludge tanks, digestion sludge tanks, effluent metering tanks, etc. How to use EchoTREK SBP/STD/STB/STV/SBB ultrasonic liquid level meter in sewage treatment plants. To make the control more reliable, you can consider adding another ultrasonic liquid level meter at the same height around it to match the previous float level switch. Compare to prevent misoperation of the water inlet pump due to failure of the liquid level switch.
1. According to the original design idea, the original PLC program control sequence can be changed to
The sequence of automatically opening the pump is:
When the liquid level is lower than 2.90 meters When the liquid level rises above 3.12 meters, a low liquid level alarm is issued;
When the liquid level rises above 3.12 meters, one pump is turned on;
When the liquid level rises above 3.34 meters, two pumps are turned on Pumps;
When the liquid level rises above 3.56 meters, three pumps are turned on;
When the liquid level rises above 3.78 meters, four pumps are turned on;
When the liquid level rises above 4.00 meters, five pumps will be turned on and a high liquid level alarm will sound.
The sequence of automatically stopping the pumps is:
When the liquid level drops below 3.78 meters, shut down one pump (turn on four pumps);
When the liquid level drops below 3.78 meters, When the liquid level drops below 3.56 meters, shut down one pump (turn on three pumps);
When the liquid level drops below 3.34 meters, shut down one pump (turn on two pumps);
< p>When the liquid level drops below 3.12 meters, one pump is turned off (one pump is turned on);When the liquid level drops below 2.90 meters, the water inlet pump is fully shut down and a low liquid level alarm is issued. ;
The starting and stopping sequence of a single pump is the same as when controlled by the float level switch.
2. In addition to the above methods, the calculation and judgment functions of PLC can also be fully utilized and redesigned with new ideas to simplify the program.
According to the original process design, the distance between the lowermost float level switch and the bottom of the pool is 2.90 meters, and the distance between every two adjacent ones is 0.22 meters. When the liquid level rises, subtract the measured value to Divide the height of the bottom float level switch by 0.22 meters and then round to the next round, which is the number of pumps to be turned on. When the liquid level drops, subtract the measured value to the height of the bottom float level switch divided by 0.22 meters. Then round up and add one to get the number of pumps to be started. When the liquid level is higher than 4.00 meters, a high liquid level alarm is issued, and when the liquid level is lower than 2.90 meters, a low liquid level alarm is issued.
3. How the EchoTREK SBP/STD/STB/STV/SBB ultrasonic level meter can be used in sewage treatment plants to realize the possibility
Modify the float level switch to control the water inlet pump After installing the ultrasonic liquid level meter, no other investment is allowed except adding an ultrasonic liquid level meter, and there is no cost to modify the software. There is no need to increase the investment in this part, and it will not have any impact on computer monitoring. After the transformation, it not only reduces the cost of the float level switch, relays, PLC modules and multiple cables and the occupation of PLC bytes, but also fully embodies the original design ideas and fully implements the abandoned automatic control part. utilization. How EchoTREK SBP/STD/STB/STV/SBB ultrasonic liquid level meter can be used in sewage treatment plants to achieve automatic control and make scientific and reasonable arrangements for the start and stop time and frequency of pumps to avoid human errors and increase operational safety. performance, reliability and stability.
If you have any questions, please contact Qingtian Instrument.