Industrial Demineralized Water Equipment
Product Overview and Positioning
The industrial demineralized water equipment manufactured by Shanghai Tongjie Environmental Protection Technology Co., Ltd. adopts a combined process of "Pretreatment + Reverse Osmosis (RO) + Mixed Bed (MB) or Electrodeionization (EDI)" to perform deep demineralization of raw water, producing demineralized water with conductivity below 0.1 μS/cm.
The equipment operates on the principles of ion exchange and membrane separation, without the need for a heat source. The produced water quality meets the low salt content requirements of various industrial applications such as high-pressure boilers, electronics cleaning, and pharmaceutical preparation.
Process Flow and Principle
Raw water first passes through the pretreatment unit to remove suspended solids, residual chlorine, and some organic matter, then enters the Reverse Osmosis (RO) unit. The RO membrane is a polyamide composite membrane that, under an operating pressure of 1.0–1.8 MPa, removes more than 97% of dissolved salts, colloids, and microorganisms from the water. The conductivity of the RO permeate is typically reduced to below 50 μS/cm.
Depending on the final water quality requirements, the RO permeate enters a deep demineralization unit, which can be configured as either a Mixed Bed (MB) or Electrodeionization (EDI) system. The mixed bed process uses a homogeneous mixture of cation and anion exchange resins. Through ion exchange reactions, residual cations and anions in the water are replaced with H⁺ and OH⁻ ions respectively, producing water with resistivity up to 18 MΩ·cm. When the mixed bed resin becomes saturated, it is regenerated using acid and alkali. The equipment is designed with dual-bed switching operation to ensure continuous water supply.
The EDI process utilizes the selective permeability of ion exchange membranes and the continuous electrical regeneration of resins under a DC electric field to transfer residual ions from the RO permeate into the concentrate stream for discharge. EDI produces water with resistivity consistently above 17 MΩ·cm, and the process does not require chemical regeneration agents. The two deep demineralization units can be selected based on site conditions and maintenance requirements.
Equipment Structure and Core Components
The equipment consists of pretreatment filters, RO membrane modules, mixed bed or EDI modules, a chemical dosing system, a cleaning system, and a PLC control cabinet.
The pretreatment includes a multimedia filter and an activated carbon filter, which remove suspended solids and adsorb residual chlorine, respectively.
The RO membrane elements are spiral-wound brackish water membranes with FRP or stainless steel pressure vessels arranged in a single-stage, two-pass configuration.
The mixed bed unit is equipped with a resin trap and a regeneration system; the EDI module adopts a plate-and-frame or spiral-wound structure with built-in ion exchange membranes and resins.
The control system uses a PLC to enable automatic operation, online conductivity monitoring, mixed bed regeneration sequence control, and fault alarms.
Key Performance Indicators and Applicable Standards
The determination of product water quality targets is based on two inputs: (1) the water quality requirements for industrial demineralized water and boiler makeup water specified in industry standards; and (2) the influent requirements of customer’s downstream equipment, the quality requirements for process media, and the characteristics of the raw water. Based on this information, the company develops a targeted indicator plan. Typical control parameters include:
Product water conductivity: The upper limit is set according to customer’s equipment requirements. Mixed bed product water can reach below 0.1 μS/cm; EDI product water can reach below 0.06 μS/cm.
Product water resistivity: In accordance with GB/T 12145 Quality standard of water and steam for thermal power plant and steam power equipment for boiler makeup water, mixed bed product water is not less than 18 MΩ·cm, and EDI product water is not less than 17 MΩ·cm.
Product water silica content: Controlled at no more than 20 μg/L, as specified in boiler feed water quality standards.
Product water hardness and residual ion content: Determined according to the inlet specifications of downstream process equipment to ensure no scale formation.
Based on the customer’s complete water quality analysis report and the intended use of the product water, the company provides a process scheme and guaranteed performance values covering the above indicators during the design phase. These values are mutually confirmed and used as the acceptance criteria for the equipment.
An ideal solution for meeting short-term or long-term decentralized water supply demands
Application Fields
This equipment is used in the power industry for high-pressure and ultra-high-pressure boiler makeup water; in the electronics industry for pretreatment and primary demineralization in ultrapure water systems; in the pharmaceutical industry for pretreatment of purified water and water for injection; in the chemical industry for process ingredient and reaction medium water; and in the food and beverage industry for production water. The product water can be directly used as boiler feed water, process rinse water, or as feed water for further polishing.
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