CN115745250A - Treatment system and method for carbon brick production waste gas washing circulating water - Google Patents

Abstract

The invention relates to a treatment system and method for cleaning circulating water of waste gas from carbon brick production. The washing circulating water of the waste gas cleaning device from carbon brick production is returned to the tar/oil slick integrated processor to remove tar and slick oil, and then enters A large amount of suspended matter is removed in the primary coagulation settler, and then lifted to the deep oil removal filter for deep oil removal, and then enters the ozone catalytic oxidizer to remove most of the organic pollutants, ammonia nitrogen and remaining oil, and then enters the adsorption The remaining organic pollutants are removed in the reactor, and then enter the secondary coagulation precipitator to remove the powdered activated carbon adsorbed with organic pollutants and the remaining suspended matter, and finally lift it into the circulating water tank for cleaning the carbon brick production waste gas Circulating water supply. The present invention treats the carbon brick production waste gas washing circulating water through a multi-stage physical and chemical combination process, greatly reduces the concentration of circulating water pollutants, meets the water quality requirements for recycling, and solves the environmental pain points and difficulties of carbon brick production wastewater.

Description

A system and method for treating waste gas washing circulating water from carbon brick production

technical field

The invention relates to a treatment system and method for washing circulating water of waste gas produced by carbon bricks.

Background technique

The blast furnace in the iron and steel industry is a smelting equipment that uses steel plates as the furnace shell, and the shell is lined with refractory bricks. From top to bottom, the blast furnace body is divided into five parts: the furnace throat, the furnace body, the furnace waist, the furnace bosh, and the hearth. Due to the good technical and economic indicators of blast furnace ironmaking, simple process, large production volume, high labor production efficiency, and low energy consumption, the iron produced by this method accounts for the vast majority of the world's total iron production. Among them, the refractory bricks used as the bottom and hearth lining of the blast furnace are carbon bricks. Carbon bricks are refractory products with high temperature resistance and good wear resistance, which are made of electric calcined coal as the main raw material and fired at high temperature with an appropriate amount of binder. Carbon bricks will produce waste gas during the high-temperature firing process. The waste gas contains a variety of oils and benzene-ring organic substances. The waste gas is discharged after being treated with circulating washing water. After the circulating washing water contacts the waste gas in the above links, the waste water Contains a large amount of organic pollutants. In order to ensure the process of recycling the exhaust gas, it is necessary to treat the circulating washing water.

At present, there are few reports on the treatment of this wastewater, and it is still in a technical blank. The water quality of this wastewater is shown in Table 1.

Table 1 Typical carbon brick production exhaust gas washing cycle water quality

project unit index suspended matter mg/L 340 Conductivity μS/cm 8.02×10⁴ Ammonia nitrogen mg/L 9.14×10³ pH dimensionless 6.02 CODcr mg/L 2.16×10⁵ Sulfide mg/L ND Petro mg/L 488 total cyanide mg/L 67.6 phenol mg/L 183 naphthalene mg/L 0.137

Due to the complex composition of the wastewater, which contains a large amount of tar, organic matter, salts, ammonia nitrogen and other pollutants, conventional water treatment processes are difficult to handle, and it also poses a large environmental safety risk. Therefore, an economically feasible treatment process is urgently needed to solve the problem of blank carbon brick production wastewater treatment technology.

Contents of the invention

The purpose of the present invention is to provide a treatment system and method for cleaning circulating water of waste gas produced by carbon bricks, through integrated treatment of tar/slick oil + primary coagulation sedimentation + deep oil removal filtration + ozone catalytic oxidation + adsorption + secondary The multi-stage physicochemical combined process of coagulation and sedimentation + recycling can treat the waste gas washing circulating water from carbon brick production, greatly reduce the concentration of pollutants in circulating water, meet the water quality requirements for recycling, and completely solve the carbon brick production industry. The pain points and difficulties in environmental protection of production wastewater in China.

In order to achieve the above object, the technical solution of the present invention is a method for processing waste gas washing circulating water produced by carbon bricks, comprising the following steps:

1) Return the washing circulating water of the carbon brick production waste gas scrubber to the integrated tar/oil slick processor, and remove the heavy tar and light slick oil at the same time by gravity;

2) After being treated by the tar/slick integrated processor, it enters the first-stage coagulation-settler, and removes a large amount of suspended solids through coagulation and sedimentation;

3) The wastewater treated by the primary coagulation settler is lifted into the deep degreasing filter for deep degreasing;

4) The wastewater treated by the deep degreasing filter enters the ozone catalytic oxidizer, and removes most of the organic pollutants, ammonia nitrogen and remaining oil through ozone catalytic oxidation;

5) The wastewater treated by the ozone catalytic oxidizer enters the adsorption reactor, and powdered activated carbon is added to the adsorption reactor at the same time, and the remaining organic pollutants are removed by powdered activated carbon adsorption;

6) The waste water treated by the adsorption reactor enters the secondary coagulation-settler, and the powdered activated carbon and the remaining suspended matter adsorbed by organic pollutants are removed by coagulation and sedimentation;

7) The water treated by the secondary coagulation-settler is lifted into the circulating water pool, and the water in the circulating pool is used for circulating water supply to the carbon brick production waste gas scrubber.

As one of the implementation methods, in step 1), the residence time of the waste water in the tar/oil slick integrated processor is 20-30 hours, and then the waste water passes through the slick oil scraping device and the bottom of the tar/oil slick integrated processor. The set tar collection and discharge device removes floating oil and tar respectively.

As one of the implementations, in step 2), after the wastewater enters the first-stage coagulation-settler, coagulant and flocculant are sequentially added and stirred. The concentration of coagulant is 50-150mg/L, and The dosing concentration is 1-2 mg/L. After the coagulation and flocculation reaction, a large amount of suspended solids will form sediment and be discharged; the total residence time of the wastewater in the primary coagulation-settler is 12-14 hours.

As one of the embodiments, the deep oil removal filter is provided with an oil removal filter material, and the oil removal filter material performs deep oil removal on the waste water through filtration and adsorption; the oil removal filter material uses a walnut shell filter material , the hydraulic load is 6-9m ³ /(m ² ·h), and the filling height is 1.5-2.5m.

As one of the embodiments, the ozone catalytic oxidizer adopts a three-stage series connection, the total residence time is 20-30h, and the single-stage height is 3m, and each stage of the ozone catalytic oxidizer is equipped with a catalyst and an ozone aeration device .

As one of the implementations, the filling rate of the catalyst is 40-80%, the catalyst is an aluminum-silicon composite supported metal oxide, the specific surface area is 200-250m ² /g, and the particle size is 3-5mm. The ozone dosage of the ozone aeration device is 30-80mg/L.

As an embodiment, in step 5), the concentration of powdered activated carbon added to the adsorption reactor is 500-700mg/L, and the residence time is 1.5-3h.

As one of the implementations, in step 6), after the wastewater enters the secondary coagulation settler, coagulant and flocculant are added in turn and stirred, the concentration of coagulant is 40-100mg/L, The dosing concentration is 1mg/L. After the coagulation and flocculation reaction, the powdered activated carbon adsorbed with organic pollutants and the remaining suspended matter form sediment and discharge; the total residence time of the wastewater in the secondary coagulation-settler is 12-14h .

As one of the implementation modes, the water outlet of the first-stage coagulation-settler is provided with an overrunning pipe, which is respectively connected to the ozone catalytic oxidizer, the second-stage coagulation-settler and the circulating water pool.

The present invention also provides a treatment system for washing circulating water of waste gas produced by carbon bricks, including a tar/slick integrated processor, a first-stage coagulation settler, a deep oil removal filter, an ozone catalytic oxidation device, an adsorption reactor, a secondary coagulation-settler, and a circulating water tank; the water outlet of the carbon brick production waste gas scrubber is connected to the water inlet of the tar/slick integrated processor, and the water outlet of the circulating water tank is connected to the The carbon brick production waste gas scrubber is connected to the water inlet.

The present invention has the following advantages after adopting the above-mentioned technical scheme:

(1) Multi-cascade treatment with high efficiency: integrated treatment of tar/slick oil + primary coagulation sedimentation + deep oil removal filtration + ozone catalytic oxidation + powder activated carbon adsorption + secondary coagulation sedimentation + multiple recycling With advanced physicochemical technology, the removal rate of COD can reach 80-85%, the removal rate of NH ₄ -N can reach 60-70%, the removal rate of SS can reach 90-95%, and the removal rate of petroleum can reach 80-90%.

(2) The system is simple: the treatment efficiency is high. After the carbon brick production waste gas washing circulating water is treated, the COD, NH ₄ -N, SS, petroleum and other pollutants in the waste water can all meet the water quality requirements of the circulating washing, no need External waste water.

(3) Reduced floor space: Through multi-cascade processing technology and the use of skid-mounted devices, it can be integrated into integrated processing skid-mounted equipment, reducing land occupation and installation difficulty.

(4) Flexible treatment: due to the small volume of circulating water for washing waste gas from carbon brick production, and the intermittent operation of the circulation system, the present invention adopts a rapid start-stop physical and chemical method, which can maintain a 100% synchronization rate with the upstream circulation washing production line , At the same time, it adopts a partial surpassing process. On the one hand, it can flexibly surpass when the upstream water flow is good, saving operating costs, and on the other hand, it can ensure the treatment effect when the upstream water flow is bad.

(5) Low investment: The multi-cascade physical and chemical processing method is adopted. Each processing unit is relatively independent and efficient, and also complements each other in processing functions, which greatly improves the processing efficiency and saves investment.

(6) Good stability: Pre-treatment is set to reduce the petroleum and suspended solids entering the ozone catalytic oxidation device. At the same time, the ozone catalytic oxidation uses a catalyst with high catalytic performance, which greatly improves the removal efficiency of pollutants. Advanced treatment is set after the ozone catalytic oxidation device, and adsorption and coagulation sedimentation are used to ensure that the effluent is reused up to the standard, so that the whole system has the advantages of strong impact load resistance and good stability.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the flow chart of the treatment process of carbon brick production exhaust gas washing circulating water that the embodiment of the present invention provides;

In the figure: 1. Carbon brick production exhaust gas scrubber; 2. Tar/slick oil integrated processor; 3. Primary coagulation settler; 4. Deep degreasing filter; 5. Ozone catalytic oxidizer; 6. Adsorption reactor; 7. Secondary coagulation settler; 8. Circulating pool.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment one

Carbon bricks are gradually heated up in the production kiln, and gradually cracked into gaseous substances containing various organic substances. After being collected through the gas collection port on the sealing cover, they are treated with dust removal gas and then enter the tail gas scrubber to wash the various organic substances cracked into water. At the same time, the temperature of the tail gas is controlled, and the washed water flows into the sump, and is lifted by the self-priming pump and sprayed into the washing tower for recycling. Due to continuous recycling, the water is gradually enriched with various complex organic substances and suspended substances, resulting in benzene The ring substances exceed the standard, the washing effect becomes poor, the heat exchange effect becomes poor, and the exhaust gas contains excessive water vapor, resulting in white smoke.

Carry out water quality testing on the washing circulating water of carbon brick production exhaust gas washing device 1, its COD _cr ≤25×10 ⁴ mg/L, ammonia nitrogen ≤1×10 ⁴ mg/L, conductivity ≤10×10 ⁴ μS/cm, SS≤400mg/L, petroleum ≤500mg/L, therefore, it is necessary to treat the washing circulating water to make the effluent meet COD _cr ≤5×10 ⁴ mg/L, ammonia nitrogen ≤0.4×10 ⁴ mg/L, SS ≤40mg/L, petroleum ≤100mg/L, meeting the requirements for recycling.

As shown in Figure 1, the present embodiment provides a method for processing waste gas washing circulating water from carbon brick production, including the following steps:

1) Return the washing circulating water of the carbon brick production exhaust gas cleaning device 1 to the tar/slick integrated processor 2, and the residence time is 24 hours; the top of the tar/slick integrated processor 2 is provided with a slick scraper In addition to the device, the bottom is equipped with a tar collection and discharge device. Under the action of gravity, the oil slick floats on the upper surface, and the tar is deposited on the bottom. The heavy tar and dense tar are removed simultaneously by the oil slick scraper device and the tar collection and discharge device. light oil slick;

2) After being treated by the tar/slick integrated processor 2, it enters the first-stage coagulation-settler 3, and the first-stage coagulation-settler 3 is successively provided with a coagulation area, a flocculation area, a sedimentation area, and an intermediate water tank; First enter the coagulation area, add coagulant to the coagulation area, the coagulant to be added is PAC, the dosage concentration is 100mg/L, and start the coagulation stirring device in the coagulation area to stir evenly; then the waste water enters In the flocculation area, add a flocculant to the flocculation area, the flocculant to be added is PAM, and the dosage concentration is 1mg/L. Suspended solids and other pollutants are trapped at the bottom of the sedimentation area and then discharged, and the clean water enters the intermediate water tank from the upper part of the sedimentation area, and then is lifted to the next stage by the lift pump; the total residence time of the wastewater in the first-stage coagulation-settler 3 is 12h ;

3) The waste water treated by the first-stage coagulation-settler 3 is lifted into the deep degreasing filter 4 through the lift pump, and the deep degreasing filter 4 is provided with degreasing filter material, and the degreasing filter material adopts walnut shell filter material , the hydraulic load is 7m ³ /(m ² ·h), and the filling height is 2m. The deoiling filter material can degrease the waste water deeply by means of filtration and adsorption, especially tar with high viscosity;

4) The wastewater treated by the deep degreasing filter 4 enters the ozone catalytic oxidizer 5, and the ozone catalytic oxidizer 5 is provided with a catalyst layer and an ozone aeration device, and the ozone aeration device is located below the catalyst layer, and the catalyst layer of the catalyst layer Aluminum-silicon composite is used as the carrier, loaded with metal oxide (Cu/TiO ₂ ), the specific surface area is 230m ² /g, the particle size is 4mm, and the dosage of ozone is 60mg/L. Most of the organic pollution is removed by ozone catalytic oxidation. substances, ammonia nitrogen and residual oil; optimally, the ozone catalytic oxidizer 5 adopts the form of three-stage series connection, the total residence time is 24h, and the single-stage height is 3m;

5) The wastewater treated by the ozone catalytic oxidizer 5 enters the adsorption reactor 6, and at the same time, powdered activated carbon is added to the adsorption reactor 6, and the stirring device arranged in the adsorption reactor 6 is started to stir evenly, and the powdered activated carbon added is The concentration is 600mg/L, and the residence time is 2h; due to the strong adsorption capacity of powdered activated carbon, the refractory dissolved organic matter that has not been removed by the previous process can be removed through the adsorption of powdered activated carbon, and the concentration of powdered activated carbon can be adjusted in real time according to the quality of incoming water. The dosage is used to adjust the treatment efficiency, and the ability to resist fluctuations in water quality is strong;

6) The wastewater treated by the adsorption reactor 6 enters the secondary coagulation-settler 7, and the secondary coagulation-settler 7 is sequentially provided with a coagulation area, a flocculation area, a sedimentation area and a discharge water tank; the wastewater first enters the coagulation Add coagulant to the coagulation area, the coagulant to be added is PAC, and the dosage concentration is 50mg/L, and at the same time start the coagulation stirring device in the coagulation area to stir evenly; then the waste water enters the flocculation area, Add flocculant to the flocculation zone, the flocculant to be added is PAM, and the dosage concentration is 1mg/L, and at the same time start the flocculation stirring device in the flocculation zone to stir evenly; then the wastewater enters the sedimentation zone, after sedimentation treatment, the front adsorption reactor 6 The powdered activated carbon adsorbed with organic pollutants and the remaining suspended solids are turned into sludge and then discharged from the system at the bottom of the sedimentation area to achieve the purpose of removing organic matter and remaining suspended solids. Clean water enters the discharge water tank from the upper part of the sedimentation area, and then Lift to the circulating pool 8 by the lifting pump; the total residence time of the waste water in the secondary coagulation settler 7 is 12h;

7) The water treated by the secondary coagulation-settler 7 is lifted into the circulating water pool 8 through the waste water lifting pump, and the circulating water lifting pump is installed in the circulating water pool 8, and the circulating water that reaches the standard is lifted to the carbon brick through the circulating water lifting pump Produce exhaust gas scrubbing device 1, and circulate water supply to it.

In this example, through the multi-stage physical and chemical combination process of tar/slick oil integrated treatment + primary coagulation precipitation + deep oil removal filtration + ozone catalytic oxidation + powder activated carbon adsorption + secondary coagulation precipitation + recycling, the carbon The waste gas from the production of plain bricks is treated by washing the circulating water, which greatly reduces the concentration of pollutants in the circulating water, meets the water quality requirements for recycling, and completely solves the environmental pain points and difficulties of production wastewater in the carbon brick production industry. The high-quality and sustainable development of production enterprises is of great significance.

To optimize the above embodiment, the outlet of the first-stage coagulation-settler 3 is provided with an overrunning pipe, which is respectively connected to the ozone catalytic oxidizer 5, the second-stage coagulation-settler 7, and the circulating water pool 8, and the first-stage coagulation-settler 3 is detected. The outlet water quality can directly pass the effluent from the first-stage coagulation-settler 3 into the ozone catalytic oxidizer 5, the second-stage coagulation-settler 7 or the circulating water pool 8, which improves the treatment efficiency and saves operating costs at the same time.

Embodiment two

This embodiment provides a treatment system for washing circulating water of exhaust gas from carbon brick production, including a tar/slick integrated processor 2, a first-stage coagulation settler 3, a deep oil removal filter 4, Ozone catalytic oxidizer 5, adsorption reactor 6, secondary coagulation precipitator 7, circulation pool 8; the water outlet of carbon brick production waste gas scrubber 1 is connected to the water inlet of tar/oil slick integrated processor 2, and the circulation The water outlet of the pool 8 is connected with the water inlet of the carbon brick production waste gas scrubber 1 . Optimally, the water outlet of the first-stage coagulation-settler 3 is also provided with an overrunning pipe, which is respectively connected to the ozone catalytic oxidizer 5, the second-stage coagulation-settler 7 and the circulating water pool 8.

The process flow of using this system to treat carbon bricks to produce waste gas washing circulating water is shown in Figure 1, and the specific process methods and parameters are detailed in Example 1.

At the same time, the processing system of this embodiment can be integrated into an integrated processing skid-mounted device, which reduces land occupation and installation difficulty.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A method for treating waste gas washing circulating water in carbon brick production is characterized by comprising the following steps:

1) Returning washing circulating water of the carbon brick production waste gas washing device to the tar/floating oil integrated processor, and simultaneously removing tar with heavy density and floating oil with light density in a gravity mode;

2) The treated oil enters a first-stage coagulating sedimentation device after being treated by a tar/floating oil integrated processor, and a large amount of suspended matters are removed in a coagulating sedimentation mode;

3) Lifting the wastewater treated by the primary coagulating sedimentation device into a deep oil removal filter for deep oil removal;

4) The wastewater treated by the deep oil removal filter enters an ozone catalytic oxidizer, and most organic pollutants, ammonia nitrogen and residual oils are removed by catalytic oxidation of ozone;

5) The wastewater treated by the ozone catalytic oxidizer enters an adsorption reactor, and meanwhile, powdered activated carbon is added into the adsorption reactor, and the residual organic pollutants are removed through adsorption of the powdered activated carbon;

6) The wastewater treated by the adsorption reactor enters a secondary coagulating sedimentation device, and the powdered activated carbon adsorbing organic pollutants and the residual suspended matters are removed in a coagulating sedimentation mode;

7) And lifting the water treated by the secondary coagulating sedimentation device into a circulating water tank, wherein the water in the circulating water tank is used for circularly supplying water to the carbon brick production waste gas washing device.

2. The method for treating the waste gas washing circulating water produced in the production of carbon bricks according to claim 1, which comprises the following steps: in the step 1), the retention time of the wastewater in the tar/oil slick integrated processor is 20-30 h, and then the oil slick and the tar are respectively removed through an oil slick scraping device arranged at the top of the tar/oil slick integrated processor and a tar collecting and discharging device arranged at the bottom of the tar/oil slick integrated processor.

3. The method for treating the waste gas washing circulating water produced in the production of carbon bricks according to claim 1, which comprises the following steps: in the step 2), after the wastewater enters a primary coagulator, sequentially adding a coagulant and a flocculant and stirring, wherein the adding concentration of the coagulant is 50-150 mg/L, the adding concentration of the flocculant is 1-2 mg/L, and after a coagulation flocculation reaction, a large amount of suspended matters form precipitates and are discharged; the total retention time of the wastewater in the first-stage coagulating sedimentation device is 12-14 h.

4. The method for treating the circulating water for washing the waste gas generated in the production of carbon bricks according to claim 1, which comprises the following steps: an oil removing filter material is arranged in the deep oil removing filter, and the oil removing filter material deeply removes oil from the wastewater in a filtering and adsorbing manner; the oil removing filter material is a walnut shell filter material, and the hydraulic load is 6-9 m ³ /(m ² H) a filling height of 1.5 to 2.5m.

5. The method for treating the circulating water for washing the waste gas generated in the production of carbon bricks according to claim 1, which comprises the following steps: the ozone catalytic oxidation device adopts a three-stage series connection mode, the total retention time is 20-30 h, the height of a single stage is 3m, and each stage of ozone catalytic oxidation device is provided with a catalyst and an ozone aeration device.

6. The method for treating the circulating water for washing the waste gas generated in the production of carbon bricks according to claim 5, wherein the method comprises the following steps: the filling rate of the catalyst is 40-80%, the catalyst adopts aluminum-silicon compound loaded metal oxide, and the specific surface area is 200-250 m ² The grain diameter is 3-5 mm, and the ozone adding amount of the ozone aeration device is 30-80 mg/L.

7. The method for treating the waste gas washing circulating water produced in the production of carbon bricks according to claim 1, which comprises the following steps: in the step 5), the concentration of the powdered activated carbon added into the adsorption reactor is 500-700 mg/L, and the retention time is 1.5-3 h.

8. The method for treating the waste gas washing circulating water produced in the production of carbon bricks according to claim 1, which comprises the following steps: in the step 6), after the wastewater enters a secondary coagulating sedimentation device, sequentially adding a coagulant and a flocculant and stirring, wherein the adding concentration of the coagulant is 40-100 mg/L, the adding concentration of the flocculant is 1mg/L, and after coagulation and flocculation reaction, the powdered activated carbon adsorbing organic pollutants and the rest suspended matters form sediment and are discharged; the total retention time of the wastewater in the secondary coagulating sedimentation device is 12-14 h.

9. The method for treating the waste gas washing circulating water produced in the production of carbon bricks according to claim 1, which comprises the following steps: and the water outlet of the primary coagulating sedimentation device is provided with an overrunning pipe which is respectively connected to the ozone catalytic oxidation device, the secondary coagulating sedimentation device and the circulating water tank.

10. The utility model provides a processing system of carbon element brick production waste gas washing circulating water which characterized in that: the device comprises a tar/floating oil integrated processor, a primary coagulating sedimentation device, a deep oil removing filter, an ozone catalytic oxidation device, an adsorption reactor, a secondary coagulating sedimentation device and a circulating water tank which are sequentially connected along the water flow direction; the water outlet of the carbon brick production waste gas washing device is connected with the water inlet of the tar/floating oil integrated processor, and the water outlet of the circulating water tank is connected with the water inlet of the carbon brick production waste gas washing device.

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