Cost optimization in steam and cooling circuits

The more condensate and residual energy is reused, the less additional make up water is required that has to be treated chemically which is expensive.



In processes with the use of pure water, the online monitoring of organic contaminants is of great importance because they may lead to damages of the whole plant. The guidelines for the quality of condensate, steam and boiler feed water are becoming more stringent. Now, it is standard to set an alarm at 0.1-0.2 mg/l C. By use of an online TOC analyser system the quality and the organic parts in steam and cooling cycles can be monitored. The aim of online monitoring is to detect contaminated streams fast and to redirect them minimising expensive pure and hot water losses. Generating steam is a costly process. A medium-sized boiler consumes about 100 m³ of water per hour and produces 100 m³ of steam per hour. The costs for energy are 25-50 € per m³. Overall, about 2,500-5,000 € per hour, means € 21.9-43.8 million a year for the generating of steam are incurred.
Following relationship exist:
Boiler feed water = make up water + condensate return water.
The more condensate and residual energy is reused, the less additional make up water is required that has to be treated chemically which is expensive. Chemical additives are added to protect the boiler and piping stystem and to keep the water in certain purity. In particular, corrosion should be avoided because it reduces the boiler's heat transfer and damages the boiler and piping system. Depending on the remaining energy a price of 6-10 €/m³ is assumed for condensate water. With a make up water price of 1-2 €/m³ when draining the water results in a loss of 7-12 €/m³. For a medium sized boiler, this means an annual loss of approximately € 6.1 to 10.5 million. These high costs can be significantly minimised by reusing the condensate and the residual energy. Contaminated water and steam can be detected by TOC measurements and redirected, so that no further damages and costs will occur. Therefore, an optimal online measurement system must be determine TOC spills accurately and fast. It must have a high availability and a long lifetime cycle with low follow-up costs.
LAR's QuickTOCcondensate is specifically designed for condensate applications. It delivers the TOC values within 1 minute. The catalyst-free ceramic oven is the centrepiece of the QuickTOCcondensate. At 1,200°C, it reliably oxidises all carbon bonds and thus enables a complete analysis of samples. The patented calibration and validation feature QuickCalibration offers the opportunity to check the analyser at any time - automaticly and/ or by remote control. Another advantage is that this unique analyser does not need any liquid standards that must be produced or purchased expensively. These innovative methods of the TOC analyser help to optimise and reduce the processes and costs in steam and cooling circuits. 

The total organic carbon (TOC) is one of the most important sum parameters in the assessment of the organic pollution of water. Since it includes all carbon compounds as one mass, it is exactly defined and an absolute quantity. Therefore, it may be determined directly.

Read more about TOC measurement methods.

Total organic carbon analyzers of LAR Process Analysers AG

The chemical oxygen demand (COD) indicates the amount of oxygen which is needed for the oxidation of all organic substances in water and is thus an important indicator for water analysis. It is considered in the planning and controlling of treatment, as well as assessing its efficiency, thus forming the basis for the calculation of waste water charges.

The COD can be determined in laboratory or online, whereby these methods significantly differ in duration and consumables used.

Read more about COD measurement methods.

COD analyzers of LAR Process Analysers AG

The biochemical oxygen demand (BOD) indicates the amount of oxygen which is needed for the biological degradation of organic substances in water.

Since the generally used BOD5 excludes the nitrification part of the process, this parameter is poorly suited for the control of waste water treatment plants. Alternatively, the total BOD is well-suited, due to the determination of the nitrogen as well as the carbonaceous part of biological degradation.

Read more about the online measurement of BOD.

Toxicity is described as the direct harmful effect of a substance on organisms. These effects can already occur at low concentraions of toxic substances and are dependent on the incubation period and the dosage.

Some test methods that are available on the market can detect toxicity by using fish, daphnia, molluscs, algae or luminous bacteria and testing whether a water sample has a toxic effect on the organisms. They do not, however, identify exactly which toxins are present.

Read more about online toxicity measurements.

BOD / toxicity analyzers of LAR Process Analysers AG

The total nitrogen bound (TNb) shows the pollution of water caused by nitrogen compounds. Nitrogen may be present as ammonia, ammonium salts, nitrites, nitrates and organic nitrogen compounds.

In contrast to single measurements of the above-mentioned components, the TNb determination contains all these substances in a single analysis process.

Read more about online TNb measurements.

The total phosphorus (TP) is a sum parameter that shows the organic and inorganic phosphorus compounds in water. Phosphorus is an essential nutrient for humans as well as flora and fauna. However, the substance – depending on its concentration– may cause serious damage.

Read more about online TP measurements.

TN TP analyzer of LAR Process Analysers AG