Chlorine dioxide generator

　　The chlorine dioxide generator consists of a kettle‑type reactor connected via an acid‑resistant conduit to a water‑jet vacuum unit. It is a compact, multi‑stage chemical‑method chlorine dioxide generator that is easy to operate, boasts high conversion efficiency and purity, offers versatile applications, and is environmentally friendly. The kettle‑type reactor employs a two‑stage or multi‑stage design; the primary reactor is equipped with an air distributor, while the secondary reactor features a balancing pipe, ensuring more complete reaction and enabling compliant discharge of residual liquid. The generated chlorine dioxide can be formulated into an aqueous solution or a stabilized chlorine dioxide solution.

　　As a novel oxidant and disinfectant, chlorine dioxide has emerged as a leading choice in the water‑treatment sector, thanks to its high efficiency, broad‑spectrum activity, absence of residual byproducts, and strong oxidative capabilities for decolorization, deodorization, and removal of off‑odors. Compared with traditional disinfectants such as ultraviolet light, ozone, sodium hypochlorite, and liquid chlorine, chlorine dioxide offers distinct advantages, making it increasingly the preferred option among industry professionals.

　　(1) System Composition

　　The chemical‑method chlorine dioxide generator consists of a feed system, a reaction system, a safety system, an automatic control system, and an absorption‑dosing system.

　　(2) Classification

　　One type is a high-purity chlorine dioxide disinfectant generator, while the other is a composite chlorine dioxide disinfectant generator. As the names suggest, the former produces chlorine dioxide as its primary product, whereas the latter generates a mixed solution containing chlorine dioxide, chlorine gas, and other components.

　　(3) Reaction Principle

　　Principle of a certain type of reaction:

　　5NaClO₂ + 4HCl = 4ClO₂ + 5NaCl + 2H₂O or 2NaClO₃ + H₂O₂ + H₂SO₄ = 2ClO₂ + Na₂SO₄ + O₂ + 2H₂O

　　2NaClO₂ + NaClO + 2HCl = 2ClO₂ + 3NaCl + H₂O

　　Type II reaction principle: NaClO₃ + 2HCl = ClO₂ + 1/2Cl₂ + NaCl + H₂O

　　Principle of the high-purity sulfuric acid process: 2NaClO3 + H2O2 + H2SO4 → 2ClO2 + Na2SO4 + O2 + 2H2O

　　(4) Use of raw materials

　　Type of raw materials used: sodium chlorite (industrial grade, ≥85% purity) and industrial-grade hydrochloric acid (≥31% concentration).

　　or concentrated sulfuric acid (industrial grade, 83.0 ± 2.0% concentration), sodium chlorate (industrial grade, ≥99% purity), hydrogen peroxide (industrial grade, ≥27.5% concentration), sodium hypochlorite 10%

　　Class II raw materials: sodium chlorate (industrial grade, ≥99% purity) and industrial-grade hydrochloric acid (≥31% concentration).

　　(5) Process Flow

　　2NaClO3 + 4HCl = 2ClO2 + Cl2 + 2NaCl + 2H2O

　　Hydrochloric acid and sodium chlorate are metered into the reactor, where, under heating, a chemical reaction produces chlorine dioxide and chlorine gas. The resulting gases are then drawn into the disinfection water stream via an eductor for dosing.

　　(6) Specification Classification

　　The specifications of chlorine dioxide disinfectant generators are determined based on the equipment’s chlorine dioxide production rate (g/h). The specifications of composite chlorine dioxide disinfectant generators are determined based on the equipment’s effective chlorine production rate (g/h).

　　(7) Performance Characteristics

　　A. The process may employ negative-pressure aeration and positive-pressure injection technologies to produce chlorine dioxide disinfectant solution.

　　B. The equipment’s core reactor is fabricated from a high‑temperature‑ and corrosion‑resistant composite material, ensuring a long service life. The reactor is designed as a multi‑stage tower with staged heating; the main reactor operates at temperatures as high as 70°C, which both maintains a high ClO₂ concentration and enhances the conversion rate of the feedstock.

　　C. The automatic control system features automatic alarm and protection functions for undervoltage, material shortage, overheating, and water shortage (with automatic shutdown).

　　D. Raw material delivery utilizes metering pumps imported from Germany, Japan, the United States, Italy, and other countries, ensuring stable and reliable operation.

　　E. The equipment’s automatic control system is highly robust, with an LED display that dynamically shows various process parameters during operation—such as temperature, pressure, liquid level, dosing rate, residual chlorine dioxide in the effluent, and influent flow rate—and allows seamless switching between manual and automatic modes. It accepts standard 4–20 mA signals for residual chlorine dioxide and influent flow rate, enabling online closed-loop control of both parameters. Additionally, it supports remote communication via a communication interface.

　　(8) Scope of Application

　　1. Disinfection of domestic, drinking, and tap water in various settings;

　　2. Sterilization and disinfection of restaurants, hotels, households, and tableware, as well as air‑environment disinfection.

　　3. Final sterilization and disinfection of equipment, pipelines, and vessels in food and beverage plants and the fermentation industry.

　　4. Sterilization of pipelines, facilities, and the environment in dairy plants and slaughterhouses;

　　5. Sterilization and disinfection of hospital wastewater;

　　6. Sterilization and disinfection of swimming pools, industrial circulating water, and bathwater;

　　7. Antifungal treatment for the disinfection, sterilization, and deodorization of hospitals, healthcare facilities, and clinical instruments;

　　8. Preservation of food and final rinse disinfection for households, hotels, restaurants, fruits and vegetables, fish, meat, and other food items;

　　9. Stock various oral disinfectants, deodorizers, and wound‑cleaning solutions, among others.

　　10. Sterilization and deodorization in wastewater reuse;

　　11. Flour and bleaching agents for various food products;

　　12. Bleaching agents for the paper-making and textile dyeing industries;

　　Basic Requirements

　　1) The design of the generator and its electrical components shall comply with the requirements of GB 19517 and GB 5083, or with the corresponding international standards and standards recognized by international organizations.

　　2) The PVC material used in the generator shall comply with the requirements of GB/T 4219.1 and QB/T 3802, or with the corresponding international standards and standards recognized by international organizations.

　　3) The manufacture of the generator shall comply with the provisions of JB/T 2932 or the relevant international standards and standards recognized by international organizations.

　　4) The generator’s reaction system shall be equipped with safety and explosion‑proof devices.

　　5) All pipelines shall be free of leaks.

　　6) The feed liquid transfer system shall be equipped with an interlock device.

　　7) The hydrochloric acid and sodium chlorate used during generator operation shall comply with the relevant national standards.

　　Technical Requirements

　　1) Chlorine dioxide disinfectant generator

　　The chlorine dioxide output of the generator shall not be less than its rated value.

　　In the disinfectant solution produced by the generator, the mass percentage of chlorine dioxide (expressed as available chlorine) shall be not less than 95% of the total available chlorine.

　　The conversion rate of the main raw material, sodium chlorite, is not less than 80%.

　　2) Chlorine dioxide composite disinfectant generator

　　1) The effective chlorine output of the generator shall not be less than its rated value.

　　In the disinfectant solution produced by the generator, the mass percentage of chlorine dioxide (expressed as available chlorine) shall be not less than 55% of the total available chlorine.

　　2) The conversion rates of key raw materials, such as sodium chlorate and sodium chlorite, shall be no less than 60%.

　　3) Under normal operating conditions, the generator shall have a service life of not less than 5 years, with a mean time between failures of not less than 8,000 hours.

　　4) Under normal operating conditions, the generator shall exhibit excellent sealing performance. When used indoors—provided adequate ventilation is ensured and the ambient temperature is maintained between 5°C and 40°C—the chlorine concentration in the indoor environment shall comply with the requirements of HJ/T 30, with a maximum permissible concentration of less than 1 mg/m³.

　　5) When used for drinking water, the total concentration of residual disinfection by-products, such as chlorite and chlorate, shall not exceed 0.7 mg/L.

　　Control Requirements

　　The control system automatically adjusts the dosage ratio in response to changes in water quality and is equipped with various safety features, including automatic shutdown upon water shortage and shutdown when no chemical is available. Under the control of an electromagnetic flowmeter, the chlorine dioxide generator delivers chemicals at a constant, pre‑set ratio in fully automatic mode, enabling unmanned operation and remote data transmission. It also includes a remote communication interface for interfacing with DCS systems.

　　Construction and Installation

　　1) The generator and the power distribution equipment should be installed in separate rooms, and each room shall be equipped with a 220 V AC power supply.

　　2) The hydrogen gas produced by the generator shall be vented outdoors, with its outlet located well away from any ignition sources. The operating room shall be equipped with explosion-proof lighting, and the premises must have adequate ventilation.

　　3) The generator is equipped with an inlet port and a disinfectant outlet; the diameter of the external piping should match these ports, and a check valve must be installed at the disinfectant outlet.

　　4) The inlet pipeline may be made of steel or plastic tubing, while the outlet medication pipeline must be made of polyvinyl chloride (PVC) or ABS plastic tubing.

　　5) Water supply and drainage facilities shall be provided adjacent to the generator.

　　6) Pay attention to equipment grounding and other related safety measures. The equipment room shall be equipped with drainage facilities, and its floor should be treated with a simple anti-corrosion coating.

　　7) A tap water supply with a pressure greater than 0.3 MPa shall be provided.

　　Implementation Standard

　　1) Product Standards

　　Technical Requirements for Environmental Protection Products: Chemical-Method Chlorine Dioxide Disinfectant Generator, HJ/T 272-2006

　　“Chemical-Method Composite Chlorine Dioxide Generator” GB/T 20621-2006

　　2. Engineering Standards

　　Code for Design of Building Water Supply and Drainage, GB 50015-2003

　　Code for Acceptance of Construction Quality of Building Water Supply, Drainage and Heating Engineering, GB 50242-2002

　　3. Relevant Standard Drawings

　　02SS104 “Selection and Installation of Secondary Water Supply Disinfection Equipment”

　　System Configuration

　　Chlorine dioxide generator host, reaction vessel, hydrochloric acid storage tank, sodium chlorate storage tank, material dissolver, material dissolving pump, hydrochloric acid metering pump, sodium chlorate metering pump, water ejector, indoor piping and valves, (water shortage alarm system, residual chlorine analyzer, PLC control cabinet, touch screen—fully automated configuration)

　　Precautions

　　1. Before the first operation, sufficient clean water must be added to the equipment; running the machine empty is strictly prohibited.

　　2. When the metering pump stops feeding, the water injector should continue to operate for at least one hour to ensure that all chlorine dioxide gas in the reactor is completely evacuated, thereby preventing gas from overflowing into the inlet pipe.

　　3. If the power‑driven water supply is suddenly interrupted, the metering valve should be closed immediately.

　　4. Hydrochloric acid is a strong acid; operators must wear protective gloves. The raw material sodium chlorite (NaClO₂) must not be stored together with any acidic substances and should be kept away from sources of ignition.

　　5. The equipment’s temperature-controlled water tank should be replenished with water regularly to prevent damage to the heater. The controller is equipped with a protective device: when the water level in the tank falls below the set threshold, the fault indicator on the control cabinet will illuminate, and water should be added immediately.

　　6. Chlorine dioxide is a strong oxidizing agent; the equipment’s flexible plastic tubing is prone to aging and may develop leaks, so it should be inspected and replaced regularly.

　　7. Regularly remove sediment from the reactor. If the liquid level indicated by the reactor’s level gauge exceeds the normal range, it indicates excessive sediment; flush the system immediately and inspect the quality of the raw materials.

　　8. When the raw materials contain impurities, they are prone to clogging; ensure regular cleaning and unclogging.

　　9. The equipment is heated by a water bath. When the equipment is not in use, drain the heating water and the reaction mixture to prevent freezing at temperatures below 0°C, which could damage the equipment. If the equipment is used intermittently, to avoid freezing of the heating water and reaction mixture, keep the temperature control unit running continuously.