General industrial cooling water usage accounts for 50% to 60% of total urban water consumption. Thermal power plants, large chemical enterprises, and metallurgy and other enterprises require a large amount of cooling water for heat exchange in their production processes.
During the operation of industrial circulating cooling water systems, water evaporation leads to increased concentration of circulating water, exceeding standards for salt content and anion and cation levels, and causing noticeable changes in pH value, which deteriorates water quality. Furthermore, the temperature, pH, and nutrients in the circulating water provide favorable conditions for microbial reproduction, and cooling towers, exposed to sunlight, become an ideal environment for algae growth. Therefore, it is necessary to implement circulating water treatment to control scaling, corrosion, and microbial growth.
The main problems in circulating cooling water
Scale:
As circulating water evaporates during the cooling process, the salt concentration in the water increases, causing certain salts to exceed their solubility and precipitate. Common examples include calcium carbonate, calcium phosphate, and magnesium silicate scales. These scales have a dense texture, significantly reducing heat transfer efficiency. A scale thickness of 0.6 mm can lead to a 20% decrease in the heat transfer coefficient.
Dirt:
Dirt in circulating water mainly consists of organic matter, microbial colonies and secretions, silt, dust, etc. Unlike scales, dirt has a fluffy texture. It not only reduces heat transfer efficiency but also causes corrosion underneath the scales, leading to a shorter equipment lifespan.
Corrosion:
Corrosion of heat transfer equipment in circulating water is mainly due to galvanic corrosion. This occurs as a result of equipment manufacturing defects, the presence of sufficient oxygen in the water, corrosive ions (such as Cl-, Fe2+, Cu2+), and the mucus secreted by microbes in the dirt. The consequences of corrosion are severe and can result in the equipment becoming unusable in a short period of time, leading to the scrapping of heat exchangers and water piping equipment.
Microbial slime:
Circulating water contains sufficient oxygen, the right temperature, and eutrophic conditions, making it an ideal environment for microbial growth and reproduction. If not controlled in a timely manner, this can quickly lead to a deterioration in water quality, odor, blackening, and the deposition of a large amount of slime scale in cooling towers, which can even cause blockages. This greatly reduces the cooling effect and increases equipment corrosion. Therefore, it is crucial to control the propagation of microorganisms in circulating water treatment.
Suspended Solids in Cooling Water
When treating cooling water, it is important to add water treatment agents like acrylic acid-acrylate copolymers. These agents effectively inhibit the formation and deposition of scale, particularly calcium carbonate, calcium sulfate, and calcium phosphate.
Water treatment agents also disperse suspended solids that are smaller than 2 microns. In most cooling water applications, suspended solids larger than 30 microns are rarely found. Due to their weight, they have difficulty entering the air stream in cooling towers and subsequently the cooling water system. Therefore, the majority of suspended solids in cooling water fall within the 2 to 30 micron size range.
Based on extensive practice and analysis, we have determined that maintaining the concentration of suspended solids in treated cooling water below 5 mg/l is crucial for the proper functioning of cooling tower systems.
The importance of cooling water filtration
1. Improve the performance of water treatment agents, reduce consumption
2. Reduce heat exchanger failure, improve heat transfer efficiency
3. Reduce cooling water consumption, reduce the increase in water supply
4. Improve the safety coefficient of equipment
Cooling water bypass filtration
Currently, sand filters and multi-media filters are widely utilized. However, the system faces the challenge of requiring a large volume of water for backwashing. Additionally, the filter media in these systems needs regular replacement, which is a cumbersome operation. Moreover, the disposal of the discarded filter media is also a drawback of sand filters and multi-media filters.
Feature-Tec Solutions
Feature-Tec's MacVital system, with its extra-large flow design and high filtration efficiency, can easily solve the problem of circulating and cooling water filtration. It is suitable for replacing automatic backwashing equipment such as sand filters and multi-media filters.
Feature Tec MacVital System
MacVital System Benefits
Mobility
Automated Operation
Compact design
Visualized interface
Savings in expenses and operating costs
Gas backwashable
Reduces solid waste and water consumption
