CN1053430C

CN1053430C - Process for treating water

Info

Publication number: CN1053430C
Application number: CN 97105004
Authority: CN
Inventors: 张小安; 杨平石; 耿殿雨
Original assignee: ZHANG XIAO AN
Current assignee: ZHANG XIAO AN
Priority date: 1997-01-07
Filing date: 1997-01-07
Publication date: 2000-06-14
Anticipated expiration: 2017-01-07
Also published as: CN1187470A

Abstract

The present invention belongs to a water processing method. A deoxidization antiscaling water processing method which sacrificing electrolyzing anodes and a device are used for processing boiler and industry cooling water. The method is characterized in that water flows through between two electrodes, wherein an anode uses an iron plate, and a cathode uses a stainless steel plate or other metal plates. Bivalent ferrous hydroxide generated by the anode reacts with dissolved oxygen in water to generate trivalent iron hydroxide which is a floc-shaped colloidal particle in water and becomes the nucleus of crystallization evolved by salt in water. Then, the trivalent iron hydroxide forms water slag which is discharged through pollution discharge.

Description

Water treatment method

The present invention belongs to a water treatment method for removing oxygen and preventing scale for boiler and industrial cooling water.

The invention is especially suitable for water treatment of hot water heating boilers, small steam boilers and circulating cooling water systems, and can prevent and reduce scaling and corrosion of the systems. The elimination of dissolved oxygen and the prevention of scale formation have long been the problem sought to be solved by research, in an effort to improve the technology.

The prior art in the aspect of oxygen removal is as follows:

1. the technique is that the water is heated to above 60 deg.C, then the dissolved oxygen is oxidized on the surface of iron filings to consume the dissolved oxygen.

2. The technology is a high-level arrangement device, is large in size and needs steam to heat water supply to over 104 ℃, so that dissolved oxygen escapes from water.

3. The oxygen is removed in vacuo and the water is heated to above 60 ℃ to allow dissolved oxygen to escape from the water under negative pressure.

The technology adopted in the aspect of scale prevention comprises magnetic field treatment, electronic treatment, electrostatic treatment and the like, which utilizes a physical method to influence or change the existence form of salts in water to achieve the purpose of scale prevention, and utilizes an ion exchange method to replace calcium and magnesium ions in the water to achieve the purpose of softening water and preventing scale. They are intensively embodied in the technical schemes provided by Chinese patent CN1090257A, Chinese patent CN1082514A, U.S. patent US3801482, U.S. patent US4872959, U.S. patent US5494559, Chinese patent CN 2106956952, Chinese patent CN95209598, Chinese patent CN1048446, Chinese patent CN1031192 and the like.

The invention aims to overcome the defects of the prior art, and a new technical method which can simultaneously solve the problems of oxygen removal and scale prevention and reduce the use cost is searched for in the aspect of water treatment of heating boilers and industrial cooling water.

The technical scheme of the invention is as follows: arranging a positive electrode and a negative electrode which are electrified with direct current, wherein the anode [1]is made of iron or iron alloy materials, the cathode [2]is made of stainless steel or other metal materials, the treated water [3]passes between the two electrodes at natural temperature, the anode is consumed in electrode reaction, and the following chemical reaction occurs in the process:

1. the reactions taking place at the cathode are:

2. the reactions occurring at the anode were:

3. in water:

as seen from the above reaction, since the generated ferrous hydroxide is oxidized into ferric hydroxide after encountering dissolved oxygen in water, the dissolved oxygen in water is eliminated. Ferric hydroxide in water forms flocculent colloidal particles which become the crystal core of salts in water, so that the separated salts form water slag which is discharged during sewage discharge. The iron has flocculation effect on calcium and magnesium salts in water, particularly has more obvious flocculation effect after a small amount of sodium hydroxide or sodium carbonate is added, and can improve the pH value and accelerate the oxidation reaction in water. If 0.1-500 ppm of sodium hydroxide or sodium carbonate or the mixture of sodium hydroxide and sodium carbonate is added into water before or after electrolysis, salt precipitation in water is accelerated, and the following chemical reactions occur:

the precipitated salts are attached to the surface of the ferric hydroxide, thus achieving the purpose of scale prevention.

This technical scheme is selected between 0.5 ~ 300mm to the interval of the two poles of the earth, aim at: firstly, considering that the operating cost can be reduced by reducing the voltage, secondly, the phenomenon that the short circuit easily occurs in the bipole deformation, therefore under the condition of taking the insulation measure between the bipoles, the distance can be controlled to be smaller, but not less than 0.5mm, under the condition of not taking the insulation measure between the bipoles, the distance between the bipoles can be larger, but when considering that the distance between the bipoles is increased, the voltage which needs to obtain the same current intensity is also increased, thereby the operating cost is increased, therefore, the maximum distance between the bipoles is not more than 300 mm.

The magnitude of the current in operation theoretically depends on the amount of water treated (ton/hour) and also on the content of dissolved oxygen in water (mg/L). According to the chemical reaction equation:

when the content of dissolved oxygen in water andthe amount of water to be treated are known, Fe (OH) required for eliminating all dissolved oxygen in water can be obtained₂The amount of the product on the anode of the electrode, and applying Faraday first electricitySolving the law:

W＝k·I·τ

the magnitude of the current can be calculated

Wherein the amount of W-electrode-forming product (in grams);

i-amperage (amps);

tau-time on (hours)

The k-proportionality constant, expressed as the amount of product formed at the electrode when the amount of charge passed at the electrode is (1A.h), is the electrochemical equivalent of the product.

And the electrochemical equivalent of a substance is proportional to its chemical equivalent E, i.e.

K＝C·E

If the electrochemical equivalent is in grams, the chemical equivalent is gram equivalent, and C is a proportionality constant

C = \frac{1}{26.8} = 0.0373

Considering the problems of uniform current distribution on the plate, functional relation between current density and equipment cost, running cost and the like, the current density on the plate is determined to be 1 muA-1.5A/cm²It is preferable.

The invention is a method to solve two problems of deoxidization and scale prevention. Compared with the prior art, the method has the advantages of reducing cost, floor area, maintenance and management personnel and the like. More importantly, the common feature of the above-mentioned oxygenremoval technologies is that the temperature of the supplied water needs to be heated, and a group of heating devices is needed for the heating industry, so that the application range of the technologies is limited by the requirements, and the technologies are difficult to adopt for the heating industry in particular.

The deoxygenation method can remove the dissolved oxygen in water to less than 0.1ppm at the natural temperature of 5-25 ℃ without heating the feed water. Simultaneously scientifically and creatively utilizes the flocculating colloid Fe (OH) in water₃Effectively prevents the salt in the water from attaching to the surface of the metal wall to achieve the purpose of scale prevention. Therefore, compared with the prior art, the application range is wider, and the method is particularly suitable for the heating industry and the like.

The accompanying drawings visually and vividly show the technical implementation method of the invention, and [1]and [2]are respectively an anode and a cathode, which only show one application unit, and in practical use, parallel connection and series connection or a mixed application method of parallel connection and series connection can be applied according to requirements, and a plurality of units are arranged at the same time.

Claims

1. A water treatment method for removing oxygen and preventing scale of boiler and industrial cooling water is characterized in that an anode [1]made of iron or iron alloy material is arranged]And a cathode [2]made of stainless steel or other metal material]Treated water [3]The anode iron is consumed between the two electrodes, ferrous hydroxide is generated and reacts with oxygen in water to generate flocculent ferric hydroxide which becomes the crystal core of salts in water, the precipitated salts form water slag to be discharged, and 0.1-500 ppm of NaOH or Na is added into the water before or after electrolysis for accelerating the reaction₂CO₃Or mixing and adding NaOH and Na₂CO₃。

2. The method of claim 1, wherein the distance between the two electrodes is 0.5 to 300 mm.

3. The water treatment method according to claim 1, wherein the current density through the two electrodes is 1 μ A to 1.5A/cm²In the meantime.