Boiler Water Biocide and Algaecide
Boiler water biocide and algaecide is a chemical agent used to inhibit and eliminate bacteria, algae and other microorganisms in boiler water. It is mainly divided into two major categories: oxidizing type and non-oxidizing type. Appropriate agents can be selected according to boiler water quality, operating conditions and microbial species, and shall be applied in accordance with correct dosing methods.
I. Functions of Boiler Water Biocide and Algaecide
During the operation of boiler water, suitable water temperature and abundant nutrients tend to cause the breeding of bacteria, algae and microorganisms. These microorganisms form biological slime attached to the inner wall of boilers and pipelines, resulting in reduced thermal efficiency, increased energy consumption, and even potential safety hazards such as corrosion and leakage.
The main function of boiler water biocide and algaecide is to inhibit and kill such microorganisms, prevent the formation of biological slime, and ensure the safe and efficient operation of boilers.
II. Types of Boiler Water Biocide and Algaecide
Boiler water biocide and algaecide are classified into oxidizing and non-oxidizing types according to chemical properties.
Oxidizing Biocide and Algaecide
Chlorine and hypochlorites: such as sodium hypochlorite and bleaching powder, sterilize by releasing hypochlorite ions. However, the efficacy of chlorine decreases under high pH conditions, and it may react with organic matter in water to produce potentially toxic substances.
Chlorine dioxide: A strong oxidant with sterilization efficiency 25 to 26 times that of chlorine. Its performance is not affected by pH value, making it suitable for various water quality conditions.
Ozone: Possesses strong oxidizing property and can kill microorganisms rapidly. It is easy to decompose and must be generated and used on site.
Non-Oxidizing Biocide and Algaecide
Quaternary ammonium salts: such as dodecyl dimethyl benzyl ammonium chloride (1227), feature broad-spectrum and high-efficiency sterilization and algae removal performance, with low toxicity and no cumulative toxicity.
Isothiazolinones: Kill microorganisms by destroying their protein structures, and are characterized by broad-spectrum high efficiency and good biodegradability.
Organic sulfur compounds: Have excellent bactericidal effect on heterotrophic bacteria, iron bacteria, sulfate-reducing bacteria and other microorganisms, with low dosage requirement and fast sterilization speed.
III. Selection of Boiler Water Biocide and Algaecide
The following factors shall be taken into account when selecting boiler water biocide and algaecide:
Boiler water quality: Different water quality has different adaptability to chemical agents; select suitable products according to water quality characteristics.
Operating conditions: Factors such as temperature, pressure and flow velocity will affect the sterilization effect and stability of the agent.
Microbial species: Different microorganisms have different sensitivity to chemicals; targeted agents shall be selected according to dominant microbial types.
Environmental protection requirements: Prioritize environmentally friendly agents to reduce environmental pollution.
IV. Dosing Methods of Boiler Water Biocide and Algaecide
Initial dosing: The dosing concentration is generally 200–300 grams per ton of water, which can remove moss, algae and slime thoroughly at one time to ensure a clean system without residues.
Regular dosing: Dose periodically according to water quality and microbial growth. In summer, add the agent every 5 to 7 days at a dosage of 150 grams per ton of water; in winter, dose every 30 days at the same dosage of 150 grams per ton of water. The specific dosing cycle and dosage can be adjusted according to actual operating conditions.
Dosing mode: The agent can be poured directly into the boiler through a dosing funnel, or added into a water tank and delivered into the boiler along with the water supply system. For large boiler systems, metering pumps can be adopted for continuous dosing to maintain stable chemical concentration.
V. Precautions for Boiler Water Biocide and Algaecide
Avoid simultaneous use with anionic surfactants, otherwise the sterilization and algae removal effect will be weakened.
Discharge and replace water in a timely manner: A large amount of dirt will be stripped into circulating water after dosing. Filtration or sewage discharge shall be conducted in time to avoid sedimentation after foam dissipates.
Regular water quality testing: Monitor microbial indicators and chemical concentration, and adjust dosage and dosing cycle according to test results.
Safe operation: Some biocides and algaecides are corrosive or toxic. Operators shall wear protective equipment to avoid contact with skin and eyes.