Comparison between CHC and traditional circulating water treatment methods

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This post was last edited by Manny_UV44b on 2019-10-21 at 15:48. Comparison between CHC and traditional circulating water treatment methods: CHC is a chemical-free circulating water treatment system that utilizes hydrocavitation technology to remove scale, eliminate bacteria and algae, and prevent corrosion, thereby ensuring the long-term stable operation of the circulating water system. Hydrocavitation refers to the creation of a state of low pressure and high flow velocity at a certain point in a pipe through which liquid flows; when the pressure of the liquid is lower than its saturated vapor pressure, the bubbles within the liquid continue to expand and increase in size. As the fluid moves, when the bubbles reach areas with high pressure and low flow velocity, they collapse and burst. The lifetime of a phenomenon bubble is approximately 0.1 μs; when it collapses suddenly, it releases enormous amounts of energy, generating micro-jets with a speed of about 110 m/s and high impact force, resulting in a collision density as high as 1.5 kg/cm2. During the sudden collapse of a bubble, localized high temperatures and pressures (5000 K, 1800 atm) are generated, with a cooling rate of up to 10 to the 9th power K/s. This is sufficient to kill the vast majority of bacteria and algae, and it can also cause bicarbonates to decompose into carbonate precipitates, carbon dioxide, and water. The three problems that circulating water needs to address are scaling, corrosion, and bacteria and algae. The differences between CHC and traditional chemical dosing methods are evident in several aspects: 1. Scale control: The formation of scale is caused by the thermal decomposition of bicarbonates, which results in carbonates adhering to the inner walls of pipes and equipment; this significantly affects heat exchange efficiency and can also lead to corrosion beneath the scale. (1) The traditional method of chemical dosing involves adding scale inhibitors to prevent scaling, and adding acid (usually sulfuric acid) to reduce pH and alkalinity, thereby lowering the likelihood of scaling. However, in actual production, scaling is inevitable in the system, especially in the heat exchangers where temperatures are high. Scale inhibitors cannot completely prevent scaling, which is why chemical manufacturers are constantly working to improve their technologies. (2) CHC causes the bicarbonates to decompose in advance within the cavitation chamber through hydraulic cavitation, resulting in the formation of carbonate precipitates. These precipitates are then removed using a centrifuge and filters integrated into the system. Water free of temporary hardness is used as the cooling medium, thereby preventing scale formation. 2. Control of corrosion: Corrosion is divided into general corrosion and local corrosion. Practice and statistics show that general corrosion accounts for 8.5%, while local corrosion accounts for 91.5%. Underscale corrosion and undersludge corrosion are the types of local corrosion with the fastest corrosion rate; it is often these types of corrosion that cause perforations and leaks in pipes and equipment. (1) The traditional approach is to use corrosion inhibitors to delay corrosion; these inhibitors are effective on smooth metal surfaces. However, once scaling occurs, their effectiveness in preventing corrosion beneath the scale is reduced, and this is the main reason why the corrosion rate in most companies does not meet the **standards. (2) Although no chemical agents are added in CHC, hydraulic cavitation prevents scaling in the system, thereby avoiding the most severe form of corrosion that occurs beneath the scale ； At the same time, the system includes pipes arranged in the circulation tank to drive away dirt and other debris from the tank to the filtration system for eventual disposal, thereby preventing dirt from entering the pipes along with the water and forming sludge, which in turn avoids corrosion caused by that sludge. This approach enables the corrosion rate of the circulating water system to remain within **standard levels. CHC also incorporates two test coupons for measuring the corrosion rate, with one further used to detect bacterial colonies. 3. Control of bacterial algae: The main hazard posed by bacterial algae is that their secretions combine with soil to form biological sludge, which causes rapid corrosion beneath it; moreover, many of the bacterial metabolites and secretions themselves are highly corrosive. (1) The traditional approach involves alternating the use of oxidative and non-oxidative bactericides, usually 2–4 times per month. In practice, the bacterial population in closed-loop water systems is unstable and fluctuates like a wave; as a result, large amounts of biological sludge are inevitably formed in the system. Otherwise, there would be no need to use sludge removers for regular treatment. (2) CHC achieves sterilization and algicidal effects through the instantaneous high temperature and pressure generated by hydraulic cavitation; this technology has passed the world’s strictest British L-8 standard certification for Legionella control. Unlike chemical treatment methods that carry out sterilization only a few times per month, CHC provides continuous sterilization on an ongoing basis, thereby maintaining the colony count within a safe range over time. Combined with the mud filtration system in the tank, it eliminates biological sludge completely. Of course, CHC also has certain limitations of its own. Apart from the comparisons mentioned above, here is a comparison of its advantages and disadvantages compared to traditional chemical dosing methods:

**Advantages/Disadvantages**
**Traditional method:** 1. Lower cost and wide applicability; 1. Treatment effectiveness falls short of expectations. 2. Low investment requirement, only a chemical dosing device is needed; 2. Frequent operation, requiring many workers. 3. Almost no need for maintenance; 3. Increases total salt content, causing environmental pollution.
**CHC:** 1. Excellent treatment effectiveness; 1. Higher initial investment cost. 2. Can reduce total salt content, thus being environmentally friendly; 2. Requires shutdown for installation. 3. Can be operated automatically; 4. Saves water and energy, resulting in very low operating costs.

Recently, there has been a push to conserve water and energy in industrial water use, as well as to control the salt content in wastewater. The main components of water treatment chemicals are salts, and acid addition for adjustment also results in the formation of salts. In recent months, many companies have been seeking appropriate solutions to this issue. CHC does not require the addition of any chemicals; removing temporary hardness alone reduces the total salt content to some extent. The removal of temporary hardness and the decrease in alkalinity increase the concentration ratio of the circulating water, thereby achieving water savings. Moreover, the system’s operation without scale or sludge over the long term also improves heat exchange efficiency, thus helping to save energy.