Choosing a filter suitable for steel plant boiler water requires comprehensive consideration of multiple factors. Here are some key considerations:

1. Raw water quality

Impurity type and content

Suspended matter and silt: If the raw water of the steel plant contains a large amount of suspended matter and silt, such as steel plants near rivers and affected by the rainy season, mechanical filters are essential. Quartz sand or anthracite filter media in mechanical filters can effectively intercept these large particles of impurities and prevent them from entering subsequent water treatment equipment.

Organic matter and residual chlorine: When there are more organic matter or residual chlorine in the raw water, such as steel plants that use urban water as raw water, activated carbon filters should be given priority. The strong adsorption capacity of activated carbon can remove organic matter, residual chlorine, color and odor in the water, preventing these substances from causing corrosion or other water quality problems in the boiler.

Hardness ions (calcium, magnesium, etc.): For raw water with higher hardness, ion exchange filters are the key choice. In some steel mills that use groundwater as raw water, the calcium and magnesium ion content in the water may be high. Ion exchange resins can remove these hardness ions, prevent the formation of scale in the boiler, reduce heat transfer efficiency and increase energy consumption.

Microorganisms and colloids: If the raw water contains a lot of microorganisms and colloids, such as seawater infiltration water from steel mills in coastal areas, ultrafiltration filters and precision filters are particularly important. Ultrafiltration filters can remove microorganisms, macromolecular organic matter and colloids, and precision filters further intercept tiny particles remaining after ultrafiltration to ensure that the water quality meets the boiler requirements.

Salt content: Under raw water conditions with high salt content, such as steel mills that use brackish water or seawater as raw water, reverse osmosis filters are an effective means of deep desalination. It can remove most of the salt in the water and produce water that meets the low salt content standard for boiler water.

Water quality fluctuations

For steel mills with large fluctuations in raw water quality, a filter combination with strong adaptability and buffering capacity should be selected. For example, in steel mills where the raw water quality changes significantly during the rainy and dry seasons, multi-stage filters can be connected in series, including mechanical filters, activated carbon filters, precision filters, etc., to cope with different water quality conditions and ensure a stable filtering effect.

2. Boiler type and parameters

Boiler pressure

Low-pressure boiler (pressure less than 1.3MPa): For low-pressure boilers, the water quality requirements are relatively low. Generally, after being treated by mechanical filters, activated carbon filters and ion exchange filters to remove suspended matter, organic matter, hardness ions and other impurities, the water demand of the boiler can be basically met.

Medium-pressure boiler (pressure between 1.3 - 3.8MPa): Medium-pressure boilers require stricter water quality control. In addition to the above basic filtering equipment, precision filters and ultrafiltration filters should also be equipped to ensure that impurities such as tiny particles and colloids in the water are completely removed to prevent the formation of deposits on the heating surface of the boiler.

High-pressure boiler (pressure greater than 3.8MPa): High-pressure boilers have extremely high water quality requirements. In this case, the reverse osmosis filter is an important component, which is used in conjunction with other filters (such as mechanical filters, activated carbon filters, ion exchange filters, precision filters and ultrafiltration filters) to provide nearly pure water inlet to the boiler through deep desalination and fine filtration.

Boiler heat load and evaporation volume

For boilers with large heat load and evaporation volume, since the circulation and treatment volume of water are also correspondingly large, it is necessary to select a filter with a larger processing capacity, and the flux and filtration speed of the filter should be considered to meet the water demand of the boiler. At the same time, in order to ensure continuous and stable water supply, the backup and switching mechanism of the filter should also be considered to prevent the boiler from lacking water due to filter maintenance or failure.

3. Operating cost

Equipment procurement cost

The price of different types of filters varies greatly. Mechanical filters and activated carbon filters are relatively low in price, while reverse osmosis filters and ultrafiltration filters are more expensive due to the advanced membrane technology involved. On the premise of meeting the boiler water quality requirements, the filter combination should be reasonably selected according to the economic strength and budget of the steel plant to avoid unnecessary equipment investment.

For example, for small steel mills with limited funds and not particularly high water quality requirements, they can give priority to the combination of mechanical filters and ion exchange filters with relatively affordable prices, and meet the basic water demand of boilers through reasonable process design.

Energy consumption cost

Some filters need to consume a lot of energy during operation. For example, reverse osmosis filters require high pressure to drive water through semipermeable membranes, so they need to be equipped with high-pressure pumps, which will increase energy consumption. When selecting filters, energy costs should be considered comprehensively. For areas with high energy prices, the use of high-energy consumption filters can be reduced by optimizing the process, or more energy-saving models and equipment can be selected.

For example, in some steel mills with high electricity costs, if the hardness of raw water is not particularly high, it is possible to consider strengthening the pretreatment effect of ion exchange filtration and reducing the deep treatment scale of reverse osmosis filtration, thereby reducing overall energy consumption.

Maintenance and consumables costs

The maintenance and consumables costs of different filters are also different. For example, ion exchange filters require regular resin regeneration, which involves the use of chemical reagents such as acids and alkalis; the membrane components of reverse osmosis filters and ultrafiltration filters need to be cleaned and replaced regularly, which will increase maintenance and consumables costs.

Therefore, when choosing a filter, the difficulty of maintenance and the cost of consumables should be considered. For steel mills with limited technical skills of maintenance personnel, filters with simple maintenance and low consumables costs should be selected, such as mechanical filters, whose main maintenance work is regular backwashing, and the cost is relatively low.

4. Floor space and space layout

Filter size and quantity

Filters of different types and specifications have different floor spaces. Mechanical filters and activated carbon filters are usually large in size, especially when the processing capacity is large, they need to occupy more space. Precision filters and ion exchange filters are relatively small. In the case of limited space in the water treatment workshop of a steel plant, the type, size and number of filters need to be reasonably selected according to the actual site size.

For example, if the site is relatively narrow, a combination of efficient and compact ultrafiltration filters and precision filters can be selected to replace some traditional filters with large floor space, and at the same time, efficient water treatment functions can be achieved through reasonable pipeline connection and layout.

Pipeline connection and supporting facilities

The pipeline connection and supporting facilities of the filter also need to consider the spatial layout. Reverse osmosis filters require supporting facilities such as high-pressure pumps and water storage tanks. The connections between these equipment need to be reasonably planned to reduce the floor space and facilitate operation and maintenance. At the same time, the direction and slope of the pipeline should also be considered to ensure smooth water flow and avoid water accumulation and backflow problems.

5. Maintenance management capabilities

Technician professional level

If the technicians of the steel plant are familiar with the technical principles, operation methods and maintenance skills of a certain filter, then when selecting the filter, they can give priority to this type of equipment. For example, for steel plants that have been using ion exchange filters for a long time, the technicians are experienced in maintenance operations such as resin regeneration. Then, when updating or expanding the water treatment system, ion exchange filters can continue to be used, combined with other new filters, to give full play to the advantages of technicians.

On the contrary, if the technicians lack understanding of some advanced membrane filters (such as reverse osmosis filters and ultrafiltration filters), then before introducing these equipment, professional training is required for the technicians to ensure that they can operate and maintain these filters correctly.

Maintenance plan and resources

Developing a reasonable maintenance plan is essential for the normal operation of the filter. Different filters have different maintenance cycles and requirements. For example, activated carbon filters require regular replacement of activated carbon, ion exchange filters require regular regeneration of resin, and reverse osmosis filters and ultrafiltration filters require regular cleaning of membrane components.

Steel mills need to choose filters that can adapt to their maintenance plans according to their own production plans and resource allocation. If maintenance resources are limited, filters with long maintenance cycles and simple operations should be selected, such as mechanical filters, which have relatively long backwash cycles and relatively simple maintenance operations, and do not require too many professional maintenance resources.