- Customer: Korea Nitto Optical (KORENO)-
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Koreno has been manufacturing the polarizing thin films for TFT LCD since July, 2000. It's a joint venture of Nitto Denko and was chosen as a high-tech company in the foreign companies' complex in Cheonbuk Industrial Complex located in Pyeongtaek City of Kyeonggi-Do, Korea by Korean government. * Location 165 Cheongbuksandan-ro Cheongbuk-myeon Pyeongtaek-si Gyeonggi-do, South Korea * Capacity - 200 million panel per month - Annual Sale $850 million per year * Main Customer Samsung Electronics Company (SEC) |
- Flow Meters Delivered: MVX Series Vortex Flow Meters and ME Series Electromagnetic Flow Meters
- Specifications:
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Vortex Flow Meter
Model: MVX-040-I-F (1 Set)
MVX-050-I-F (2 Sets
MVX-080-I-F (1 Set)
MVX-100-I-F (3 Sets)
- Fluid: Saturated Steam (Density: 7.128 Kg/m3) - Flow Rates: From 1200 to 7000 Kg/h (Span) - Connection: JIS 10K Flanges
- Material:
Body & Flange - SUS 316 & SUS 304 Indicator - Cast Aluminum - Oper'/Design Pressure: 10 barg / 16 barG - Oper'/Design Temperature: 194.279℃ / 350℃ - Flow Direction: Right to LeftBOT -TOP - Power: 24VDC
- Output: Pulse
- Accuracy: ± 1%, Reading
Quantity: 7 Sets
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1. Background
The end user, Korea Nitto Optical (KORENO), is currently expanding their production capacity by building a new plant besides the existing plant over three phases. The facility our meters were delivered to and installed for was built as part of the 1st phase. And the contract for this phase was awarded to POSCO Engineering Co., Ltd. And the part of the contract where the system for heating control and the waste water control shall be built was subcontracted to Kukje Building Management System Co., Ltd.Kukje BMS then selected our MaxiFlo MVX series vortex flow meters and ME series electromagnetic flow meters to measure and control the flows of steam and waste water.
2. Production and Delivery
A total of 7 vortex flow meters of varying sizes from 40mm to 100mm for measuring saturated steam and 3 electromagnetic flow meters of 100m (together with a batch controller for each electromagnetic flow meter) for measuring waste water were ordered in the middle of September 2013. And they were all delivered in time (20 days after receiving the downpayment) and were installed by Kukje BMS site engineers.All the meters were set up and calibrated according to the order specifications and therefore, all the installing engineers had to do was to insert the meters between the flanges of pipes according to the flow directions, tighten the flange bolts, connect the powers and output cables, and up they went. Oh, not quite.
3. Troubles and Sorting Them Out
About 1 month had passed since we had delivered the meters and received all the payment, when the site manager of Kukje BMS called us up and said that they suspected that the electromagnetic flow meters were not giving pulse outputs to the batch controllers (we delivered these, too, as a package) and asked us to visit the site and solve the problem.After checking everying was done correctly as was supposed to over the phone, I decided to pay a visit to the site rather to be just nice than to look into what was really going on, because I was sure that some very simple thing was missing and it could be sorted out in minutes.
At the site, I checked first the indicators of the 3 batch controllers that were supposed to receive output pulse signals from the electromagnetic flow meters to see that one was showing value and the other 2 did not register any values. It later turned out that the other 2 were not wired correctly. They had connected the cables to 4-20mA output instead of the pulse output terminals. So, there were no problem with the electromagnetic flow meters or with the batch controllers, exactly as I had envisioned. Further the site engineers confirmed that all the elctromagnetic flow meters were showing accurate flows and the batch controllers were acting as they were supposed to,i.e., starting the pumps and stopping them when the batch is full.
And then the site engineer casually said that they were not receiving any pulses from the vortex flow meters. So, I went, "What? Why didn't you tell me about it before? I could have been better prepared, had I known that there were such problem with the vortex flow meters." I was not upset but was quite alerted becase I didn't expect this even in my wildest dream because they have kept silence about it for such a long time after installation. Anyways, we went upstairs where the vortex flow meters for steam were installed.
Pipings of steam were all installed at elevated locations close to the ceiling and the walls. I guessed it was to save the plant space and for safety reasons because steam pipes are very hot usually over 200 degrees. And therefore it was extremely difficult and dangerous to climb up and get access to where the meters were installed. One site engineer went up and shouted that the indicators were all dead and there were no signs of the meter working. "That's really strange.", I thought. So, I climbed up and confirmed that it was actually true was really surprised. I measured the supply voltage with a multimeter and confirmed that the power was 24VDC and was correct. Then I moved to the next one and repeated the same thing. In doing so, I found one indicator was severely damaged by a burn. I stopped the work because it was too late close to the off-duty hour. I showed the burnt indicator to the site manager, explained to him that possibly a user's mistake of applying 220VAC could have been the cause of all the problems and suggested him that I would come back with a new one to replace this burnt one. But for the other ones, I didn't have any clue whatsoever that might be causing the problem. So, I thought it better to start from the beginning step by step with the new set and try to see what differences can there be. When I came back to the office, I took a photo of the burnt boards as below. It's literaly scorched.
When I visited the site again with the new indicator, it powered on ok. At this point I got more confused. Why wouldn't the other ones power on? I decided to test the other ones by replacing the circuit boards with those of new one. I first opened the back cover of the indicator to expose the terminal strips and the circuit boards of another one. I loosened the 3 screws and at that moment, one of the site engineers who was watching what I was doing said that the indicator powered on, and then off again. What happened was that when the circuit board touched the indicator chassis, which is connected to the sensor body, then to the pipe and then finally to ground, the indicator turned off, but when the circuit board was lifted away and not touching the chassis, it powered on, even though it was not showing any flow rate, while it should. I could worry about the flow reading later. What was important was to have all the meters power on first.
Now, I made a progress to finding the cause of the problem. But why was it happening? What happened to the circuits?
I concluded that all the meters were damaged in their internal circuit because the installing engineers first applied 220VAC by mistake.
So, I explained to this to the site manager and told them that all the circuit boards had to be replaced. The site manager agreed and we removed all the indicators and took them back to our facility.
Back at our facility, we tested each board from the site by applying power, and then having it connected and disconnected to the building's ground. It confirmed that the situation at the site was replicated at our facility. We then took new boards and repeated the same test but what happened with the boards from the site didn't happen with the new boards. At this point I conferred with confidence that they applied wrong power (not necessarily 220VAC because there were 24 VAC instead of 24VDC, too.).
On the 3rd visit, I started reinstalling the indicators from a big pipe (100mm). It powered on ok and to my great relief, it showed the flow rate value. So, I shouted to myself, "Yeah, way to go". Then did the rest of the meters at the same place one by one. As a result, 2 100mm pipes showed values, 80mm, on and off and 50mm, none. When I finished replacing the indicators of the 4 meters, it was already late. So, I called it a day and decided to come back the next day.
On the 4th visit, I replaced the remaining 3 sets. The result was that 100mm showed flow rate but 50mm and 40mm didn't show the flow rates. But I confirmed that there were no error with the indicator and the sensor by observing the indicator while kicking on the pipe near the sensor. When I did, the indicator showed value briefly because the vibration of the pipe increased the impact of vortices sensed by the detector.
Now, I declared that the work was finished and complete, and that successfully. In summary, all 4 meters on big pipes (100mm and 80mm) showed the flow rates, but the other 3 meters on small pipes (50mm and 40mm) didn't show flow rates. Given the results, the site manager confirmed that the valves were not fully open, the system was designed to host the eventual demand when the plant was finished over 3 phases. So, the system was running at 1/3 of it's designed capacity. Therefore he agreed that the flow rates of the smaller pipes are below the minium flow velocity requirement of 4 m/s. So, I asked him to open the valves just for test purpose to establish that the other flow meters for smaller pipes were actually ok. But he said that he had no authority to do it and was satisfied with the result in hand.
He then asked to see the pulse signals coming from the meters to PLC distribution panel. So, I took the pulse counter and connected to several meters that were showing the values and in came the signals. Bingo! Job done.
4. Epilogue
As one can see, from the beginning, there were no problem with the 7 sets of our MVX series vortex flow meters delivered. The site engineers mistakenly hooked up 24 VAC instead of 24VDC and burnt up the circuits of the indicators, which they indirectly admitted. They said if it was actually true, then they could claim the damages on the PLC subcontractor who designed the power supply for the meters.I personally paid 4 visits to the site because all our engineers were out installing the ultrasonic flow meters at other sites. And I was the only one available and with required knowledge (though I admit it's not that sufficient). I had cuts and bruises during the work. I had to replace 8 circuitboards entirely. And that cost was very high.
But I didn't mentioned any of it to the site manager. My only focus was on solving the problem and getting the hands-on experience with vortex flow meters and steam because we have little experience with them both. And it was quite an experience and good and resourceful experience.
After the job was finished, I searched the internet for some knowledges about steam and this is what I first found. You can enjoy them, too.
Goods places to learn about Steam
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However, the original design persists more or less and is still the preferred flow meter when it comes to measuring the flow of water in large quantities. It is known as the Woltman flow meter.
답글삭제Flowmeter Types