Refining

In industry water is used for various processes, e.g. for heating, for cooling, as steam to drive turbines, as a reaction medium and for cleaning. Depending on the application water requires a specific quality / purity.

Water Management in Refineries

As in other industries, water is used as a raw, auxiliary and/or operating material in a variety of processes. Water management and adequate monitoring are necessary for an efficient and trouble-free production. Impurities or faults in the process lead to deposition and corrosion, the formation of transformation products within the water cycle (e.g. Disinfection By-Products) or to product losses and contamination of the water cycle. Therefore, the continuous monitoring of various water streams is of special importance.

Explosive gasses, vapours and/or mist are often present in industrial plants of the upstream / exploitation sector and any spark could cause an explosion. Nevertheless, online water analyzers need to be installed as close as possible to the process to ensure fast analyses. For this reason, special precautions must be taken.

Normally, the installation of analyzers is made in Ex-proof certified containers that meet the requirements of the respective Ex zone. However, the construction of such a container is expensive and in most cases, the access to these shelters is limited due to special safety precautions. Stand-alone analyzers that are directly equipped with Ex-proof housings remedy the situation.

In accordance with international regulations and standards (EN 60079-2:2011-11 and IEC 600079-2), LAR offers a wide range of tailor-made protective housings for their online water analyzers.

Types of water used in industry

Schematic presentation of types of water used in industry
Schematic presentation of types of water used in industry

Raw Water

To meet the demand of water, the industry uses raw water from springs, surface water or drinking water sources. Depending on the application, the water must have a specific quality. Under certain circumstances treatment of the water must take place. In order to determine the quality of raw water and to protect the water system against contamination continuous monitoring is indispensable. As monitoring parameters the TOC (total organic carbon), COD (chemical oxygen demand), and toxicity are used.

Depending on the raw water source the measuring technique has to deal with different challenges. In contrast to surface water, water from springs and drinking water are almost pure. Therefore, the measurement technique must be specialized to low measurement ranges. When surface water from rivers and lakes is used animal and plant residues (organic material) such as algae, bacteria or shells can be present, whereby the measurement technique has to deal with organic particles and when sea water is used, high salt concentrations have to be dealt with.

Treated Water

Depending on the purpose for which the water is drawn, the raw water must be pretreated to boiler feed water, cooling water or pure water. For this, sand and activated carbon filter, desalination and decalcification facilities as well as reverse osmosis are used. After the pretreatment the water is monitored for impurities to protect the downstream water system and/or to ensure a high quality production.

For continuous monitoring application-specific analyzers for the measurement of pure water with low particle density are recommended.

Water-steam-cycles

Boiler feed water is used for the operation of boiler plants. In general, the treated water is supplied to a steam generator. A portion of the steam produced therein drives a turbine and thus generates electricity. The other portion is used for heating processes. During the heat transfer the steam produced cools down and condenses.

Pollution and interferences in water-steam cycles are responsible for nearly 50% of all unwanted downtimes in power plants. The main reasons here are corrosion and deposits. Depending on the type of power plant, circuit design and the materials used, the water chemistry can vary. Moreover, the water sample has a high temperature. As a consequence, online analyzers used within this application have to align to the measurement tasks of the boiler feed water application. Otherwise, contamination is detected too late or not at all.

Industrial Waste Water

Generally, waste water is characterized by suspended and dissolved pollutants. In contrast to municipal waste water, industrial waste water has a more complex water matrix. It may contain chemicals that are highly toxic. Such water requires a more intensive treatment than municipal waste water. Therefore, the difficulties associated with industrial waste water are enormous. Whether adhesive properties, high and fluctuating loads or diverse water matrices, industrial waste water treatment plants must be adapted to specific water compositions in order to optimally perform the cleaning process. For an efficient monitoring, the measurement technique must be adjusted to the specific challenges of difficult water samples.

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