CN102091522A - Method and equipment for removing alkaline waste water of zirconium silicate by smoke and dust - Google Patents

Abstract

The invention relates to equipment for removing alkaline waste water of zirconium silicate by acidic smoke, adopting a wet desulfurizer, and comprising perforated cylinders and a spray thrower, wherein the perforated cylinders are concentrically arranged above the cavity body of a water film deduster; the spray thrower is installed above the perforated cylinders; the perforated cylinders are put on a bracket; the other end of the bracket is positioned at the bottom of the cavity body of the water film deduster; and both the perforated cylinders and the bracket are fixed to the inner wall of the cavity body by a stabilizing frame. Alkaline waste water is input into the spray thrower of the wet desulfurizer and sprayed by a nozzle to form smog in the cavity body; and acid waste water enters the cavity body through a smoke inlet along the tangential direction, and generates neutralization with the alkaline waste water. In the invention, waste is treated by waste water, thus saving large funds and manpower, effectively solving the pollution of environment caused by the two wastes of strong acidity and strong basicity, and especially solving the problem of waste water treatment of zirconium silicate pertinently.

Description

Method and equipment for eliminating zirconium silicate alkaline wastewater by using flue gas and dust

technical field

The invention relates to a method and equipment for treating zirconium silicate alkaline wastewater, in particular to a method and equipment for eliminating zirconium silicate alkaline wastewater by using flue gas and dust.

Background technique

Zirconium and its compounds are more and more widely used in national defense and civilian products, especially in structural ceramics and functional ceramics, involving machinery, electronics, energy and other fields.

For the production process of zirconium oxychloride (zirconia), the one-acid-one-alkali method is commonly used at home and abroad, and the boiling chlorination method is a relatively advanced zircon decomposition method in the world. Zirconium oxychloride (zirconia) products have a very broad application prospect in nickel-metal hydride power battery anode materials (hydrogen storage material AB2), fuel cells (especially high-temperature solid oxide fuel cells), and battery separator paper. The development of zirconium and its compounds in China is not very fast, but the zirconium silicate alkaline wastewater produced by it has brought many problems to environmental protection.

The strongly alkaline (PH=12--13) wastewater produced after the production of zirconium oxychloride contains more zirconium silicates and the like. The current treatment process is very simple. After passing through the regulating tank, it enters the flocculation tank for sedimentation, and then enters the inclined tube sedimentation tank. However, from the preliminary treatment of high silicate alkaline wastewater, there are many suspended solids in the effluent water, and the water body is still whitish. The alum flowers that appear in the flocculation tank are small and difficult to settle. When the pH value of the raw water is adjusted to below 9 during flocculation and sedimentation A similar jelly-like substance is formed without adding any other agents (this jelly-like substance should be orthosilicic acid, which cannot be settled directly, and PAC and PAM can basically not settle down; or stir vigorously after forming a jelly-like substance The effect of adding PAC and PAM after dilution is still very poor.) According to various experimental information from the laboratory, it is difficult to achieve a treatment plan that is simple and easy to implement and suitable for industrial scale operation.

At the same time, with the improvement of the level of industrialization, the consumption of energy has also risen sharply. Coal occupies an important proportion in my country's energy structure. When coal is burned, it will produce a lot of soot and sulfur dioxide and other substances that pollute the environment. Sulfur dioxide is the main culprit of acid rain. Therefore, the relevant national laws and regulations have become more and more strict on the control of the emission level of smoke and sulfur dioxide. At the same time, there is an urgent need to post-process the flue gas after combustion to make it meet the emission standards stipulated by relevant regulations. The smoke and dust rich in acidic oxidizing organisms, such as disulfur dioxide and nitrogen trioxide, is discharged into the atmosphere and encounters water vapor to form sulfuric acid, sulfurous acid, and nitric acid, forming acid rain, which is extremely harmful.

Acidic wastewater and alkali-containing wastewater are two typical industrial wastewater. Some acidic wastewater contains inorganic acids (such as sulfuric acid, nitric acid, hydrochloric acid, etc.), and some contain organic acids (such as acetic acid, formic acid, citric acid, etc.). Alkaline wastewater contains alkaline substances, such as caustic soda, sodium carbonate, sodium sulfide, ammonia, etc.

When the mass fraction of acid in wastewater is greater than 3%-5%, it is called waste acid, and when the mass fraction of alkali in wastewater is greater than 1%-3%, it is called waste lye. When the mass fraction of acid in wastewater is less than 3%-5% or the mass fraction of alkali is less than 1%-3%, it is called acid wastewater and alkaline wastewater. Acid-base wastewater can be divided into the following categories according to the pH value:

Strong acid wastewater PH<4.5, weak acid wastewater PH=4.5-6.5

Neutral wastewater PH = 6.5-8.5 weak alkaline wastewater PH = 8.5-10.0, strong alkaline wastewater PH > 10.0.

To sum up, the two types of wastewater need to invest special funds and a lot of technical force in the currently commonly used treatment schemes, which will undoubtedly bring severe tests to enterprises.

Contents of the invention

The above-mentioned two types of industrial wastes that produce strong alkali wastewater and acid waste gas are currently facing environmental protection problems. In order to solve the above technical problems, the present invention provides a method for eliminating zirconium silicate alkaline wastewater by using acidic flue gas and dust. The method and equipment use waste water to treat waste, save a lot of money and manpower, and effectively solve the environmental pollution caused by the strong acid and strong alkali of the two types of waste, and especially solve the problem of zirconium silicate waste water treatment in a targeted manner.

The dust removal and desulfurization equipment provided by the invention not only has a high dust removal and desulfurization rate, but also enables the discharged flue gas after treatment to meet the requirements of relevant laws and regulations, and also specifically solves the strong alkalinity of the zirconium silicate solution. It tends to be neutral, and has the advantages of easy installation, low price and no need to take up valuable space.

The invention provides a swirl type wet desulfurizer, which is concentrically fixed above the cavity of a conventional water film dust collector by a cylindrical screen cylinder and installed on the screen cylinder The swirl scrubber formed by the sprayers 3 above together. The principle of this design is: the flue gas is discharged into the flue gas inlet 8 of the wet desulfurizer, and the high-silicate alkaline wastewater is input into the ring pipes 4 and 6 of the wet desulfurizer through a special pipeline to implement the neutralization process. The structure of the sprayer 3: the spraying devices respectively arranged in the middle and the upper part of the cavity, each layer of spraying devices are three rows, each row is composed of two nozzles, the diameter of the nozzle is 1.5 mm; or the sprayer 3 It is a circular pipe with the same diameter as the screen cylinder 7 and installed concentrically. Four liquid inlet pipes 11 are evenly installed along the circumference of the circular pipe, and there are many nozzles on the lower side of the circular pipe. The average concentration of sulfur dioxide in the flue gas is 150mg/m ³ . Since the size of the dust particles is only 0.8 μm to 5 μm, these particles are suspended in the desulfurizer to form smoke, while the particles of zirconium silicate alkaline wastewater sprayed by the nozzle The size is 3 μm to 5 μm. When the soot particles are smaller than the size of the high silicate alkaline wastewater spray particles, the soot particles are surrounded by the high silicate alkaline wastewater spray particles. When the soot particles are equal to the high silicate alkaline wastewater particle size Hours, the spray particles and the high silicate alkaline wastewater particles adhere one-to-one. When the soot particles are larger than the high silicate alkaline wastewater particle size, the soot particles are surrounded by the high silicate alkaline wastewater spray particles In this way, the high silicate alkaline wastewater with soot particles sinks into the circulating pool together, because in the high silicate alkaline wastewater sprayed for the first time, only the outer layer of each droplet adheres The soot particles undergo chemical action, but no chemical and adhesion phenomena occur inside the soot particles, so the two waste materials that descend into the circulating pool still have the possibility of continuing to undergo adhesion and chemical action. This phenomenon is taken into consideration in our design, so multiple injection cycles are carried out, and a liquid collector is installed at the outlet of the flue gas so that the flue gas discharged out of the desulfurizer does not contain moisture. (As shown in accompanying drawing 1).

The screen cylinder fixed in the cavity of the water film dust collector is a multi-layered concentric winding of a certain aperture, a certain width and a length of the screen into a cylindrical shape, and a multi-layer circular screen with a certain aperture on the bottom. constituted. The length and width of the screen mesh constituting the side are determined by the flue gas discharge of the boiler. Generally, its length should be such that the number of layers on the side of the final screen cylinder is about 5-30 layers, preferably 12-20 layers, round The outer diameter of the cylinder is preferably about 0.7-0.8 of the inner diameter of the cavity, and its width (that is, the height of the screen cylinder) accounts for about 1/4-1/2 of the height of the entire water film dust collector, preferably about 1/3 . If the height is too large, the dust removal space below will be reduced, and the dust-rich flue gas will enter the screen cylinder, causing blockage, and the dust removal space below also has a certain desulfurization or neutralization effect. Excessive reduction of this space will also reduce Desulfurization effect; if the height is too small, the contact area with the flue gas will be reduced, thereby reducing the desulfurization effect.

The screen mesh constituting the side and bottom surface of the screen cylinder can be made of any high temperature resistant and corrosion resistant material (such as stainless steel). Their apertures can be the same or different, generally 3.6mm respectively. If the aperture is too small, the dust in the flue gas will block the mesh; if the aperture is too large, the speed of the flue gas passing through the screen cylinder will be accelerated, and the sulfur removal effect will decrease.

The screens constituting the side and bottom surfaces of the screen cylinder can be made from mesh wires of a certain diameter, respectively. The selection of mesh diameter mainly considers manufacturing cost and corrosion resistance factors. The larger the diameter, the higher the price of the screen, and the higher the manufacturing cost of the cyclone scrubber; if the diameter is too small, the service life of the cyclone scrubber will be shortened due to corrosion. The diameter of the mesh is generally 0.5-1.5mm.

There is a bracket made of high-temperature and corrosion-resistant materials (such as stainless steel) under the screen cylinder. The screen cylinder is placed on the bracket, and the side of the screen cylinder is fixed on the side of the dust collector cavity with a stabilizer. on the inner wall. The other end of the bracket is placed at the bottom of the dust collector cavity and fixed on the inner wall of the dust collector cavity with a stabilizer. The height of the bracket depends on the height of the water film dust collector itself. If the bracket is too high, the bottom position of the cyclone scrubber (that is, the installation height of the screen cylinder) will rise, causing the height of the screen cylinder to drop, thereby reducing the sulfur removal efficiency. If the bracket is too low, the dust removal space will be reduced.

The cyclone scrubber in the dust removal and desulfurization equipment of the present invention also includes a sprayer 3 located above the screen cylinder. The sprayer of the patent of the present invention can be capable of spraying zirconium silicate alkaline waste water to the screen cylinder, and the liquid collector 5 is also installed at the outlet of the flue gas in the dust removal and desulfurization equipment. The drop collector 5 can be made up of multilayer (usually 4-5 layers) screen meshes made of high temperature resistant and corrosion resistant materials (such as stainless steel). The aperture of the screen is usually 0.5-6mm. The purpose is to further reduce the water content in the flue gas after desulfurization, so as to prevent the water vapor from reacting with the residual acid particles in the flue gas to form acid rain and discharge into the atmosphere.

During use, the flue gas enters the dust removal and desulfurization equipment of the present invention from the flue gas inlet 8 at the lower part of the water film dust collector along the tangential direction, and the flue gas rotates and rises in the cavity. Under the action of centrifugal force, the dust particles are flung to the wall of the cavity and are adhered by the zirconium silicate alkaline wastewater liquid film and undergo chemical action, because the zirconium silicate alkaline wastewater is initially treated from the original production plant There are more suspended solids in the effluent, forming an alkaline waste liquid similar to jelly, and its colloidal properties are mentioned by the way:

Air μ=17.9×10 ^-6 Pa·s, v=14.8×10 ^-6 m/s

Water μ=1.01×10 ^-3 Pa·s, v=1.01×10 ^-6 m/s

Zirconium silicate alkaline wastewater μ=1.33Pa·s, v=1.19×10 ^-4 m/s

In summary, zirconium silicate alkaline wastewater is used as a medium for flue gas treatment, and the water and its zirconium silicate solution have a certain colloidal adhesion, which can make the acidic oxides in the flue dust And zirconium silicate prolonged and more thorough chemical action all play a positive role. Also be designed with the reason place of screen cloth among the present invention.

Fine dust particles and sulfur dioxide enter the cyclone scrubber together with the flue gas. The scrubber is equipped with layers of screens, the gas enters the screen cylinder from the side of the screen cylinder, and a sprinkler is installed above the screen cylinder. In addition to the reaction between the atomized part of the zirconium silicate alkaline wastewater sprayed out by the shower and the acid-base particles, part of it forms a water flow, which is sprinkled on the screen to form uniform liquid bubbles. Under the action of the airflow, the liquid bubbles on the screen are "boiling", and a large number of bubbles are formed, and then burst, accompanied by a small amount of liquid to form droplets. Since the trapping process of the screen is the joint action of mesh wire, liquid film, and liquid droplets, it has a high trapping capacity for fine particles and gaseous pollutants. In addition, since all the gas passes through the liquid film, the gas-liquid contact is quite sufficient on the mesh surface. A neutralization reaction occurs with the alkaline waste liquid. In summary, most of the dust particles and sulfur dioxide in the gas have a neutralization reaction with the zirconium silicate mist in the sprayer area, and the other part is on the mesh surface. The neutralization reaction with the zirconium silicate solution is finally discharged by the waste water outlet 9. The flue gas treated in the cyclone scrubber enters the swirl plate demister (a stainless steel plate placed at an angle, not shown in the figure) in the liquid dropper, so that the flue gas-moisture is separated, and the water is separated The final flue gas rises to the multi-layer screen in the drop collector to further remove moisture. The purified flue gas enters the chimney from the upper part and is exhausted into the atmosphere.

Description of drawings

Fig. 1 is the sectional view of cyclone type wet desulfurizer of the present invention;

Fig. 2 is a cross-sectional view of the cyclone wet desulfurizer of the present invention along the line B-B;

Fig. 3 is a cross-sectional view along line A-A of the cyclone wet desulfurizer of the present invention.

Detailed ways

The preferred examples of the patent of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the flue gas enters the water film dust collector from the flue gas inlet 8, and rotates up in the cavity, and the larger dust particles are thrown to the inner cavity wall to have a chemical reaction with the zirconium silicate alkaline wastewater. Discharge from waste water outlet 9. Fine dust particles and sulfur dioxide enter together with the flue gas into the screen 7 concentric with the cavity fixed by the bracket 1 and the stabilizer 2 . The screen cylinder 7 is equipped with layers of screens, and the gas enters the screen cylinder from the side of the screen cylinder 7, and the sprinkler 3 with ring pipes 4 and 6 is arranged above the screen cylinder 7 (see accompanying drawing 3 ). The sprayer 3 is a circular pipe with the same diameter as the screen cylinder and installed concentrically, and the lower part of the circular pipe has many spray ports. Zirconium silicate alkaline wastewater is supplied to the sprayer 3 through four liquid inlet pipes 11 (see FIG. 3 ), so that the zirconium silicate alkaline wastewater sprayed out from each liquid injection port has a uniform pressure. The zirconium silicate alkaline waste water stream sprayed out by the sprayer 3 forms uniform liquid bubbles on the screen. Under the action of the airflow, the liquid bubbles on the screen are "boiling", and a large number of bubbles are formed, and then burst, accompanied by a small amount of zirconium silicate alkaline wastewater to form droplets. The dust particles and sulfur dioxide in the gas are absorbed and reacted by the liquid film, and then discharged from the outlet of the neutralized high silicate alkaline wastewater at the bottom of the chamber. A liquid dropper 5 is installed above the cyclone scrubber, and the liquid dropper filters the moisture contained in the treated gas to separate gas from water, and the purified flue gas enters the chimney from the upper flue gas outlet 10 , into the atmosphere.

Example 1

Test of Cyclone Scrubber on Boiler

Under standard working conditions, the concentration of sulfur dioxide was measured at the flue gas inlet of the water film dust collector and at the flue gas outlet of the water film dust collector using a cyclone scrubber, respectively, using a Thermo Model 40 sulfur dioxide analyzer made in the United States. Experiments were carried out with two different concentrations of silicate alkaline wastewater, and the results are shown in Table 1:

Table 1

It can be seen from Table 1 that after installing the cyclone scrubber, when the initial pH value of zirconate alkaline wastewater was 9, the removal rate of sulfur dioxide was 72.6%, and when the initial pH value was 11, the removal rate of sulfur dioxide was 94.7%. At the same time, the alkalinity of zirconium silicate alkaline wastewater dropped to 7.

The existing boiler water film deduster is used to add a swirl scrubber to form a swirl type wet desulfurizer patented by the present invention. It has a high dust removal and desulfurization rate, so that the treated flue gas can meet the requirements of relevant regulations, and it has the advantages of convenient installation, low price and no need to occupy additional valuable space.

Claims (11)

1. An equipment for eliminating zirconium silicate alkaline waste water by acid flue gas, adopts wet desulfurizer, it is characterized in that, described wet desulfurizer is a cyclone scrubber, is included in the chamber of water film deduster A screen cylinder (7) arranged concentrically above and a sprinkler (3) installed above the screen cylinder, the screen cylinder (7) is placed on a support (1), and the other end of the support (1) Located at the bottom of the cavity of the water film dust collector, the screen cylinder (7) and the support (1) are both fixed on the inner wall of the cavity by a stabilizing frame (2). 2. equipment as claimed in claim 1, is characterized in that, described sprinkler (3) comprises the two-layer sprinkler device that is respectively arranged on the middle part and the upper part of described water film deduster cavity, each layer of spray The unit has three rows, each consisting of two nozzles. 3. The equipment according to claim 1, characterized in that, the shower (3) is a ring pipe with the same diameter as the screen cylinder (7) and is installed concentrically, and four ring pipes are evenly installed along the circumference Liquid inlet pipe (11), and there are many nozzles on the lower side of the annular pipe. 4. The equipment according to any one of claims 1-3, characterized in that, the screen cylinder (7) is a concentric multi-layer winding of a certain aperture, a certain width and a length of the screen into a cylindrical shape and Its bottom is equipped with a multi-layer circular screen with a certain aperture. 5. The equipment according to claim 4, characterized in that, the number of layers on the side of the screen cylinder (7) is 5-30 layers, and its outer diameter is 0.7-0.8 of the inner diameter of the water film dust collector cavity. , whose height is 1/4-1/2 of the height of the water film dust collector. 6. The equipment according to claim 5, characterized in that, the screens constituting the side and bottom surfaces of the screen cylinder (7) are all made of high temperature resistant and corrosion resistant materials with an aperture of 3.6 mm. 7. The device according to claim 6, characterized in that, the screens constituting the side and bottom surfaces of the screen cylinder (7) are all made of mesh wires with a diameter of 0.5-1.5 mm. 8. The equipment according to any one of claims 1-3, characterized in that a droplet collector (5) is installed at the flue gas outlet (10) above the wet desulfurizer. 9. The equipment according to any one of claims 1-3, characterized in that the acidic flue gas enters the chamber along a tangential line from the flue gas inlet (8) at the lower part of the water film dust collector. 10. the method that utilizes acid flue gas to eliminate the equipment that zirconium silicate alkaline waste water adopts as claimed in claim 1-9, it is characterized in that, described alkaline waste water is inputted into the sprinkler (3 of wet desulfurizer) ), the smoke is sprayed out from the nozzle to form smoke in the cavity; the acid waste water enters the cavity through the flue gas inlet (8) along a tangential line, and neutralizes with the alkaline waste water. 11. method as claimed in claim 10 is characterized in that, acid flue gas enters in the cavity of described water film deduster, and acid flue gas enters screen mesh cylinder (7) from the side of screen mesh cylinder (7), sprays Part of the alkaline waste water sprayed by the shower (3) forms a water flow, which is sprinkled on the screen to form uniform bubbles, and the acid fume and alkaline waste water are neutralized and reacted on the screen, and finally discharged from the waste water outlet (9).

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