True Professional Engineer
This is a blog to share my experience in manufacturing / industrial engineering and management system setup.
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Friday, August 25, 2017

Example in setting up SOP for electrode boiler feed water de-ionization system

In the past, we normally carry out training to our subordinate with hands holding practice. But with new management style of educated management team today, a lot of SOP with standard format are requested. The amount of paperwork also increased tremendously, to the extend that wometimes there is no time to spend in production floor.

Below is an SOP prepared to train my engineering subordinate on maintenance of de-ionization system for electrode boiler. It is posted for sharing, and as a record that I so this now. 😂

To provide as training material for basic understanding on why de-ionization system is required for our electrode boiler and to provide a clear guide on how to maintain the system effectively.

To cover a brief explanation on the importance of de-ionization system with regards to electrode boiler.

To explain detail procedures in checking functionality of de-ionization column together with conductivity meter function.

3.1 Engineers/Executives

3.2 Engineering Supervisors

4.1 CONTROLLED COPY to be kept by HOD

4.2 UN-CONTROLLED COPY to be kept in [Engineering FOM Folder]

5.1 Refer to EQUIPMENT LOG AND FILING PROCEDURE for how to manage completed log sheets.

5.2 Electrode Steam Boiler Log.

5.3 ROC CCT-3300 series Conductivity Controller Operation Manual

Total Dissolved Solids (TDS) are the total amount of movable charged ions, including positively charged Cations and negatively charged Anions. These ions are originated from dissolved minerals, salts or metals in a given volume of water. It is expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm).

TDS is directly related to the purity and quality of water. Water with higher content of TDS is known as hard water. If we boil hard water, after the water being evaporated, the dissolved solids will be depositing on heating surface and form scale on the surfaces. More deposit will be formed when we boil water with higher TDS.

Water fed into boiler must be with high quality with minimum TDS. This is to ensure that no or minimum scale will be built up on the heating surfaces. Formation of scale on heating surfaces will retard heat transfer rate and if the rate of heat transfer is too low, then the heating elements will be overheated and burnt easily.

As conductivity is easier to measure, it is used in algorithms estimating salinity and TDS, both of which affect water quality. Depending on the steaming rate, the quality of water required will be different. Our electrode boiler steaming rate is comparatively low and thus only ion exchange columns are used for our de-ionization process to improve water quality.

Deionization is the process by which mineral ions in water are removed. Using specific ion-exchange resins (an insoluble matrix usually found in a bead shape), the ions in water can be drawn out and replaced. First, water flows through a certain resin that will cause the cations in the water to be drawn out, replacing the cations with hydrogen ions (cations) instead. The water, now very acidic, runs through another resin that will absorb the anions in the water, replacing these ions with hydroxide anions. The hydrogen and hydroxide will then combine to form water in a chemical reaction, leaving mineral-free water with very low TDS which will then minimize scaling of heating elements in our electrode boilers.

When the hydrogen and hydroxide ions are depleted in the resins column, the de-ionization effect will be low. In such case TDS will be increased and the conductivity measured will be higher too. This means that the de-ionization column would have to be sent for regeneration.
One important point to take note is that water flow rate passing through ion exchange column plays an important part in efficiency of ion exchange.

Parameters Setting as below:
Parameter order
Electrode Constant
Radis point setting
Measurement Unit
4mA transfer value setting
20mA transfer value setting
Alarm High Limit
Alarm Release

Note: The conductivity meter we used on the boiler feed water system is ROC CCT-3300 series conductivity controller (our unit is CCT-3200T for display only).  Refer to the CCT-3300 Series conductivity controller manual for detail on how to set the parameters.

8.1 How to carry out spot check on functionality of de-ionization system.

8.2 The engineering supervisor should go up to boiler platform and carry out the following check as a spot check to the effectiveness of technician in carry out their duty in logging boiler log.

8.3 It is advisable for the supervisor to shut the feed water supply to de-ionization system and feed water tank for 30 minutes to create some room before carrying out the following trial.

8.4 Check inlet and outlet connections to both de-ionization column and make sure that they are connected to the correct inlet and outlet holes. Take note on the IN and OUT marking on the cap.

8.5 Check all fittings in and out from the boiler, including those for the boiler gauge glass. Any deposit of white particle on the fittings indicates some minor steam leakage and the white particle that deposit after evaporation of steam or water is an indication of high TDS water.

8.6 After the water level in the feed water tank drop approximately 1 inch, the room in the tank would be good enough for the following test.

8.7 Turn on the supply valve to de-ionization system again and confirmed that water pressure drop across the system is lesser than 1.0 bar.

8.8 Partially close the valve toward the flow meter and set it to approximately 6 LPM (Litres per minute).

8.9 Check the conductivity meter and confirm that the conductivity is lower than 1µS/CM (microSimens per CM).

8.10 Set the flow rate back to approximately 6 LPM and let the system run back to normal.

8.11 During the above spot check, if the conductivity of feed water goes beyond 1µS/CM and the related technician who carry out boiler log did not report. Please guide accordingly. In case of repeated mistake, please carry out necessary disciplinary action.

8.12 Carry out the following procedures if the conductivity goes beyond 1µS/CM.

8.13 Change over to use the other column and carry out all above steps to double check that the new column is performing as expected.

8.14 Removed the exhausted column from system and replaced it with the standing by new unit.

8.15 Report to Engineer/Executive immediately for arrangement to re-generate the exhausted de-ionization column.

8.16 The duty is not end. Make sure you follow up within the week that the PR and PO are issued, old column removed to regenerate and regenerated column sent back to our plant.

8.17 The responsibility of supervisor only ends after the stand by unit of de-ionization column had been set back to stand by.

Tuesday, June 27, 2017

Power supply to control system

With the introduction of  PLC (Programmable Control Logic) into industrial automation, the use of 24 VDC power supply become a norm.

Industrial automation company such as Allen Bradley and Siemens, together with others companies like Phoenix, Omron and etc. do supply high quality power supply units. These are normally quite high in cost and they are claimed to be "more safe and stable".

After all,
  1. Are this claims justify the duty they provided?
  2. What is the differences between this and normal 24 Volts DC power supply unit?
  3. Is there any possibility that we can repair the power supply unit ourselves?
On browsing the internet, I come across this Power Supply Repair E-Handbook and believe it will give you the answer. You can checkout here to buy the product.

Note: sometimes, the links provided might be not accessible due to some WIFI setting. In such case, try it again when you are in a different WIFI coverage.

Monday, June 26, 2017

High technology problem after a electrical power shutdown

A recent expansion called for incoming electrical power shutdown for installation of new VCB (Vacuum Circuit Breaker).

It had been a normal practice that engineering team has to standby to rectify issues caused by power shutdown. I always refer to this as the "high technology problem", because this type of problem seldom happen to the traditional equipment with hard wired control circuit.

As the digital technology advanced, a lot of control had been digitized. More and more companies are now promoting the "4th Industrial Revolution". I believe that this is the right direction but sometimes I cannot stop myself doubting on how many of those involved really understand the practical problems behind this development.

Digitizing means more electronic components are used in plant automation. The advantages for electronic components are low power consumption, higher flexibility in equipment production and modification.  Nevertheless, digitizing also means that higher chances of component failure caused by electrical surge.

With a high number of PLCs and VFDs used in the plant automation, it had been a norm that a few VFD fail after power shutdown. This time, five VFDs need to be replaced.

The same happen to earth leakage and over current relays. One unit is replaced this time.

There may be someone thinking that it is caused by unhealthy electrical quality. The fact is we had carried out various electrical quality check and the same problem never end.

One other problem that frequently faced is the Ethernet communication used for production line PLCs and VFDs. The lines are fully auto, with ability to set in recipe which is known as flexibility. But the system tends to lost communication. Sometimes problem is rectified by replacement if Ethernet switches, but quite often the issue is solved by a few restarting of the control system and/or unplugging and plugging of Ethernet cables. We believe this is not a professional method, but it works.


New start to an old blog

This blog had been created for sometimes. For various reasons, it had not been updated effectively.

Today, I had decided to re-design its outlook and you can notice a lot of books appeared as its background on the bookshelf. This is one of the main reason because there are so much to share and yet there is so little time to write post.

Believing that Rome is not built in one day, with this new start, I will post idea as it appears and will progress to share any information which I find useful and believe they will help my audiences as it progress. Any comment will be welcome and I will try my best to improve along the way.

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