background

The Mars animal feed processing plant located in Frieden, Germany operates its boiler room in accordance with the standards issued by local certification bodies and the European unified standards DIN EN 12952 and 12953. This is also in line with the previously applied Technical Steam Directions (TRD).

The processing plant has formulated special measures for 72 hours of unsupervised operation of the boiler room in accordance with relevant requirements [1-5]. If FOG Fats, Oil and Grease contamination occurs in the recycled condensate, a reliable system is needed to prevent this contamination from entering the steam generator. Through online monitoring, the actual function of the system has been enhanced, and it can issue instructions for automatic discharge of contaminated condensate water.

The product specifications released by boiler manufacturers stipulate that boiler feedwater and returned condensate water must not contain organic pollutants.

Although the feedwater in the boiler comes from a controlled process, the returned condensate may be contaminated during the heat exchange process, so it must be closely monitored.

The previous approach of using ultraviolet sensors to detect organic pollution in condensate water has been phased out due to inaccurate measurement results and high maintenance requirements.

If the particulate matter content in the condensate is too high, it will not only interfere with optical measurements, but also accumulate on the optical window, and the optical window needs to be cleaned multiple times a day. In addition, UV sensors are not sensitive enough to detect low concentrations of organic compounds in condensed water.

　　Solution

Traditional sensors cannot effectively detect organic pollution, while total organic carbon (TOC) analyzers can provide users with comprehensive organic monitoring solutions. The TOC analyzer can not only detect any type of organic matter, but also integrate it into the production system for rapid online analysis. At the same time, the success or failure of the automatic monitoring system and the ability to minimize downtime also play a key role in sample preparation.

The temperature of condensed water increases and is often contaminated by particulate matter generated by pipeline corrosion (see Figure 1), and may also contain chemicals used for boiler maintenance. The pH value of condensed water is in the neutral to alkaline range.

Mars company's processing plant discovered a large amount of rust like particles in the condensate water. Although these particles are not organic pollutants, they can deposit and block the pipelines in the analyzer, thereby affecting the analysis.

Therefore, for the application in this article, sample preparation is crucial to ensure the accuracy and robustness of the analysis results. The processing plant has decided to trial the Sievers * M9 online TOC analyzer, which has been proven to be effective in the field of condensate monitoring, and prepare samples according to the specific requirements of this application.

The purpose of using the Sievers M9 TOC analyzer is to test the sample preparation and filtration process jointly established by the Sievers analyzer and an engineering company. The filtration process has the following characteristics:

• High temperature resistance up to 150 ° C • High pressure resistance up to 60 bar

Professional use of stainless steel filter components, sturdy and durable, resistant to acid and alkali corrosion

The rapid circulation filter has self-cleaning function, so the maintenance requirements are low

There are multiple options for filter aperture ranging from 1 µ m to 200 µ m, which can meet different applications. This trial uses a 5 µ m filter element (see Figure 5)

• Equipped with filtrate flow monitoring function

• Backwash filter and filtrate tube function (optional)

DOC filter or cooling coil in the filtrate flow (optional)

The device is compact in size (see Figure 2)

The Sievers M9 TOC analyzer adopts Sievers' professional membrane conductivity detection technology, which can ensure the accuracy of measurement [6,7]. The membrane conductivity detection technology uses a breathable membrane, which only allows carbon dioxide generated by organic matter oxidation to pass through the membrane to prevent other oxidation by-products from interfering with the measurement, thus providing accurate measurement results (see Figure 4). The Sievers M9 TOC analyzer has the advantages of low maintenance requirements, long calibration stability period, and high accuracy in measuring extremely low concentrations of organic matter, making it an ideal monitoring device for recovering condensate water. The advantages of this analyzer also include: no need for instrument air, minimal reagent consumption during continuous operation, short measurement time, compact size, and easy operation.

　　Conclusion

The Sievers M9 online TOC analyzer provides stable and accurate measurement data, suitable for monitoring low concentration recovered condensate water with 30-60 ppb TOC.

Simultaneously using upstream sample filtration and TOC analysis can greatly reduce maintenance costs, improve measurement sensitivity, and shorten downtime, which UV sensors cannot achieve. Our recommendation for maintenance work is to flush the entire filtration system with 0.1M HCl within the specified time frame (every 1-3 months).

Using a fast loop filter makes sample preparation simple, reliable, and requires low maintenance. Despite the high particulate matter content in the filtrate, the filtrate flow rate is still much higher than the 50 milliliters per minute required by the analyzer, thanks to the self-cleaning function designed by the filter manufacturer. We found that a 5 µ m pore size filter is sufficient to prevent clogging of the analyzer.

The trial results have proven that the Sievers M9 TOC analyzer, when paired with a sample filtration device, is a reliable monitoring system that can effectively monitor organic pollution in recycled condensate water and any challenging samples from Mars' processing plant. The Sievers M9 TOC analyzer and filtration device have not malfunctioned during the trial operation and do not require maintenance, providing reliable and accurate measurement data for the processing plant and ensuring the smooth operation of production equipment.

　　References

[1]:Water-tube boilers and auxiliary installations-Part 12:Requirements for boiler feedwater and boiler water quality; German version EN 12952-12:2003.

[2]:Shell boilers-Part 10:Requirements for boiler feedwater and boiler water quality; German version EN 12953-10:2003.

[3]:Section 2 TRD 604 Sheet 2–Additional requirements for the equipment of the steam boiler system(Excluded on 1 January 2013 by the Decree of 17 October 2012(GMBl S.902)).

[4]:Water-tube boilers and auxiliary installations-Part 7:Requirements for equipment for the boiler; German version EN 12952-7:2012.

[5]:Shell boilers-Part 6:Requirements for equipment for the boiler; German version EN 12953-6:2011.

[6]:'ASTM E2656-16 Standard Practice for Realtime Release Testing of Pharmaceutical Water for the Total Organic Carbon Attribute'.

[7]:Standard Methods for the examination of water and wastewater,23rd edition,2017,5310 Total Organic Carbon(TOC).