CN214781299U - Zero-discharge treatment system for active coke flue gas purification acid-making wastewater - Google Patents

Abstract

The utility model provides an active burnt gas cleaning system acid waste water zero release processing system, include: the defluorination subsystem is used for removing fluoride ions in the acid-making wastewater: the evaporative crystallization subsystem is communicated with the defluorination subsystem and is used for carrying out evaporative crystallization on the acid making wastewater to separate out a sodium chloride product; and the bipolar membrane subsystem is communicated with the evaporation crystallization subsystem and receives part of acid making wastewater continuously discharged by the evaporation crystallization subsystem, and is used for treating the part of acid making wastewater to prepare acid liquid and alkali liquid. Because the acid making wastewater contains a certain amount of sodium sulfate, the concentration of the sodium sulfate is ensured to be less than the crystallization point of the sodium sulfate by continuously discharging a part of the acid making wastewater with a small flow, thereby ensuring the product quality of sodium chloride. In addition, the bipolar membrane subsystem is used for treating part of acid-making wastewater discharged by the evaporation crystallization subsystem to prepare acid liquid and alkali liquid, and the acid liquid and the alkali liquid can be used for other water treatment processes.

Description

Zero-discharge treatment system for active coke flue gas purification acid-making wastewater

Technical Field

The utility model relates to an industrial wastewater treatment technical field especially relates to an active burnt gas cleaning system acid waste water zero release processing system.

Background

The common flue gas purification methods in iron and steel industry enterprises are chemical, wet, semi-dry, dry and the like. Among the various flue gas purification technologies, the activated coke flue gas purification technology has the advantages of mature technical conditions, high desulfurization efficiency, good adaptability to units and the like, and becomes one of the most widely applied steel smelting ultralow emission flue gas purification technologies. The active coke flue gas purification technology takes coal-based active coke as an adsorbent to adsorb and remove SO in flue gas₂The absorbed active coke is regenerated by heating, and the high-concentration SO is resolved₂The mixed gas can be directly used for preparing commercial concentrated sulfuric acid, thereby realizing resource utilization of sulfur. The sulfur-rich gas generated by the technical analysis tower enters an acid making unit to generate sulfuric acid, part of wastewater is generated in a desulfurization acid making process, and the wastewater discharged from a workshop after the wastewater is subjected to removal treatment is returned to a sintering water adding system after meeting the requirement of a pollutant discharge limit value of the workshop discharge port in the emission Standard of Water pollutants for iron and Steel industry (GB 13456-2012). Dewatering the slurry to obtain mud cake, returning to raw material field, and mixing with sintered ore.

The existing acid-making wastewater is recycled to a sintering water-adding system, and the following problems exist:

1) after chloride ions enter an active carbon system, the flowability of active carbon particles is deteriorated, the active carbon is easy to accumulate and generate heat, and SO is adsorbed₂The temperature can be rapidly increased in the process, so that the risk of fire disaster is caused;

2) the corrosion of high chloride ions to sintering machines, large flues, electric dust removal of machine heads and active carbon systems is aggravated;

3) chloride ions are enriched due to the adsorption of the activated carbon, and the activated carbon has inactivation risk;

4) the concentration of chloride ions in the sulfur-rich gas in the desorption tower is further improved, so that the concentration of chloride ions in the acid-making wastewater is further improved, and the chloride ions are circularly enriched in the system.

The prior acid-making wastewater is applied to a sintering wet desulphurization system and has the following problems:

1) the serious corrosion of the equipment of the desulfurization system is easily caused, and the accidents of the desulfurization tower and the dust remover body are rotten and penetrated;

2) the filter bag of the dust collector has high chloride ion content, so that the air permeability of the filter bag is gradually reduced, the pressure difference is continuously increased, and the service life of the filter bag is shortened;

3) the problem of breakage caused by high pressure difference occurs for many times, and the risk of exceeding the standard of particulate matter emission exists.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an active burnt gas cleaning system acid waste water zero release processing system can separate the chloride ion in the system acid waste water and crystallize and produce the sodium chloride product, and the system acid waste water retrieval and utilization after the processing adds the water system to the sintering, has solved the influence of system acid waste water to the follow-up procedure equipment corruption, finally reaches the waste water zero release, has realized waste water resourceization when the environmental protection.

In order to achieve the aim, the utility model provides an active burnt gas cleaning system acid waste water zero release processing system, include:

the defluorination subsystem is used for removing fluoride ions in the acid-making wastewater:

the evaporative crystallization subsystem is communicated with the defluorination subsystem and is used for carrying out evaporative crystallization on the acid making wastewater to separate out a sodium chloride product;

and the bipolar membrane subsystem is communicated with the evaporation crystallization subsystem and receives part of acid making wastewater continuously discharged by the evaporation crystallization subsystem, and is used for treating the part of acid making wastewater to prepare acid liquid and alkali liquid.

Optionally, the fluorine removal subsystem comprises:

the chemical precipitation fluorine removal device adopts a fluorine removal medicament to carry out chemical precipitation on the acid making wastewater so as to remove fluorine ions in the acid making wastewater;

the flocculation and precipitation device is used for carrying out flocculation and precipitation on the acid making wastewater by adopting a flocculation medicament so as to remove fluorine ions in the acid making wastewater;

and the clarification and precipitation device is used for clarifying and precipitating the acid making wastewater so as to separate suspended matters in the acid making wastewater from the acid making wastewater.

Optionally, the fluorine removal agent is sodium metaaluminate.

Optionally, the flocculating agent is polyacrylamide.

Optionally, the evaporative crystallization subsystem comprises, in serial communication:

the evaporative crystallization device is used for carrying out evaporative crystallization on the acid making wastewater to obtain sodium chloride salt and condensed water;

a centrifugal device for separating the sodium chloride salt from the acid-making wastewater;

and the drying device is used for drying the sodium chloride salt to produce qualified sodium chloride dry salt.

Optionally, the evaporative crystallization device is an MVR evaporator.

Optionally, the drying device is a drying fluidized bed.

Optionally, the centrifuge device is a centrifuge.

Optionally, the bipolar membrane subsystem comprises, in serial communication:

the diluting device is communicated with the evaporative crystallization subsystem and receives part of acid making wastewater continuously discharged by the evaporative crystallization subsystem, and is used for adding industrial fresh water into the part of acid making wastewater for dilution;

the calcium and magnesium removing device is used for removing calcium ions and magnesium ions in the part of acid making wastewater;

and the bipolar membrane device is used for treating part of acid making wastewater to prepare acid liquor and alkali liquor.

Optionally, the calcium and magnesium removing device comprises chelating resin.

The utility model provides an active burnt gas cleaning system acid waste water zero release processing system handles system acid waste water through removing fluorine subsystem earlier, can contain the fluorine with the play water and fall below 20mg/L, satisfies the technological requirement who gets into the evaporation crystallization subsystem, then passes through the evaporation crystallization subsystem carries out the evaporation crystallization, and output sodium chloride is meanwhile, receives through bipolar membrane subsystem evaporation crystallization subsystem lasts exhaust part system acid waste water to guarantee that evaporation crystallization subsystem's system acid waste water sodium sulfate's concentration is less than its crystallization point, thereby ensure the product quality of sodium chloride. In addition, the bipolar membrane subsystem is used for treating part of acid-making wastewater discharged by the evaporation crystallization subsystem to prepare acid liquid and alkali liquid, and the acid liquid and the alkali liquid can be used for other water treatment processes. The utility model provides an influence of system acid waste water to the follow-up process equipment corruption, finally reach the waste water zero release, realized waste water resourceization when the environmental protection.

Drawings

FIG. 1 is a schematic view of an active coke flue gas purification acid-making wastewater zero-discharge treatment system provided by an embodiment of the utility model;

FIG. 2 is a flow chart of the zero discharge treatment method for the wastewater from acid production by purification of activated coke flue gas provided by the embodiment of the utility model;

wherein the reference numerals are:

10-a defluorination subsystem; 11-a chemical precipitation defluorination device; 12-a flocculation and precipitation device; 13-a clarification and sedimentation device; 20-evaporative crystallization subsystem; 21-an evaporative crystallization device; 22-a centrifuge device; 23-a drying device; 30-a bipolar membrane subsystem; 31-a dilution unit; 32-a calcium and magnesium removal device; 33-bipolar membrane device.

Detailed Description

Through investigation, the final destination of the wastewater is different due to the difference of environmental evaluation requirements of the activated carbon purification process adopted in the sintering process of the domestic steel plant. The waste water generated by adopting the activated carbon adsorption desulfurization process mainly comprises the following steps: the blast furnace slag flushing, the steelmaking slag smothering and the workshop pretreatment are discharged into a comprehensive wastewater treatment station in a factory.

The main problems of each process are as follows:

A) blast furnace slag flushing

1) The blast furnace granulated slag is used for manufacturing cement building materials, and the quality of the granulated slag is influenced by high chloride ions, so that the quality of the granulated slag is unqualified. In addition, mercury contained in the wastewater enters the grain slag, which may cause the excessive mercury in the grain slag and influence the quality of building materials;

2) the existing wastewater is discharged into a blast furnace water slag system, the existing water slag water balance is damaged, and the wastewater overflows to a rain drainage system to generate pollution, so that an environment-friendly event is caused;

3) at present, the latest blast furnace adopts a water granulated slag system by a mini-beam method, water in the system is recycled, and if acid-making wastewater enters a circulating water tank once, the concentration of toxic and harmful substances brought by the acid-making wastewater can be continuously and circularly enriched, so that the corrosion of equipment is aggravated and the health of maintainers is influenced.

B) Slag smoldering in steel making

Currently, the Zhanjiang iron and steel base sintering wastewater adopts a steelmaking smoldering treatment mode. Because the indexes of the salt content, ammonia nitrogen and the like of the waste water are high, after the waste water is used, the peculiar smell is found in a slag treatment area, the environment is not friendly, and meanwhile, the corrosion of gas generated by slag stuffiness of the waste water to plants and equipment is serious.

C) Comprehensive wastewater treatment station for discharging pretreated workshop into factory

And (4) after removing substances such as suspended matters, heavy metal ions and the like from the wastewater generated by desulfurization through a workshop pretreatment device, discharging the wastewater into a whole-plant wastewater treatment station for comprehensive treatment. The workshop wastewater pretreatment device has no chloride ion removal process, is discharged to a comprehensive wastewater treatment station, and causes the increase of chloride of the wastewater treatment station. The influence of high chloride ion components is not considered in common wastewater stations, and the materials of the existing in-station equipment, pipelines and the like are not suitable for high chloride ion media. Meanwhile, a plurality of comprehensive water outlets are not monitored by heavy metal indexes, and certain environmental protection risks are caused after the water outlets are introduced into the wastewater.

In conclusion, the acid-making wastewater produced by the existing sintering activated carbon purification process does not have a good outlet. Based on this, the utility model provides an active burnt gas cleaning system acid waste water zero release processing system can follow country, enterprise's environmental protection angle right system acid waste water carries out the zero release and handles, will chloride ion among the system acid waste water separates and the crystallization produces the industrial product sodium chloride, and the system acid waste water retrieval and utilization after handling adds the water system to the sintering, solves the influence of system acid waste water to the follow-up process equipment corruption, has realized waste water resource when protecting the environment.

The following description of the embodiments of the present invention will be described in more detail with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.

As shown in figure 1, figure 1 is a schematic diagram of an active coke flue gas purification acid-making wastewater zero-emission treatment system provided by the embodiment of the utility model. The embodiment provides an active burnt gas cleaning system acid waste water zero release processing system, includes:

the defluorination subsystem 10 is used for removing fluorine ions in the acid-making wastewater:

the evaporative crystallization subsystem 20 is communicated with the defluorination subsystem 10 and is used for carrying out evaporative crystallization on the acid making wastewater to separate out a sodium chloride product;

and the bipolar membrane subsystem 30 is communicated with the evaporative crystallization subsystem 20 and receives part of acid making wastewater continuously discharged by the evaporative crystallization subsystem 20, and the bipolar membrane subsystem 30 is used for treating the part of acid making wastewater to prepare acid liquor and alkali liquor.

Specifically, in this embodiment, the water quality of the acid production wastewater is approximately as follows:

TABLE 1

The data in table 1 show that the acid-making wastewater mainly contains sodium chloride, contains less sodium sulfate and contains a certain amount of fluoride ions. Because the fluorine ions in the acid making wastewater are high, the excessive fluorine ions entering the subsequent evaporation crystallization equipment can cause corrosion (such as a titanium alloy wall of an MVR evaporator), and the service life of the equipment is influenced, so that the fluorine removal treatment is firstly carried out.

In this embodiment, the fluorine removal subsystem 10 includes:

the chemical precipitation fluorine removal device 11 is used for carrying out chemical precipitation on the acid making wastewater by adopting a fluorine removal medicament so as to remove fluorine ions in the acid making wastewater;

a flocculation and precipitation device 12 for performing flocculation and precipitation on the acid production wastewater by using a flocculation reagent to remove fluorine ions in the acid production wastewater;

and the clarification and precipitation device 13 is used for clarifying and precipitating the acid making wastewater so as to separate suspended matters in the acid making wastewater from the acid making wastewater.

During specific operation, make the system acid waste water get into chemical precipitation defluorination device 11, add the defluorination medicament, produce the flocculation and precipitation behind the medicament fully reaction, then add the flocculation medicament in flocculation and precipitation device 12 and strengthen the settlement effect, it is right through clarification precipitation device 13 at last system acid waste water carries out the clarification sediment, with suspended solid and the system acid waste water separation in the system acid waste water, the warp except that after the processing of fluorine subsystem 10, can contain fluorine with the play water and fall below 20mg/L, satisfy the technological requirement that gets into the MVR evaporimeter.

In this embodiment, the chemical precipitation fluorine removal device 11, the flocculation and precipitation device 12, and the clarification and precipitation device 13 may be manufactured as an integrated device, and simultaneously achieve the three functions, or may be designed as different devices, which is not limited in this application.

In this embodiment, the fluorine removing agent includes, but is not limited to, sodium metaaluminate, and the concentration is about 3000 ppm.

In this embodiment, the flocculation reagent includes, but is not limited to, polyacrylamide, and can greatly improve the strength and settling rate of the floc, and the formed floc has high strength and good settling property, thereby improving the solid-liquid separation rate.

Further, the evaporative crystallization subsystem 20 includes, in serial communication:

the evaporative crystallization device 21 is used for carrying out evaporative crystallization on the acid making wastewater to obtain sodium chloride salt and condensed water;

a centrifugal device 22 for separating the sodium chloride salt from the acid production wastewater;

and the drying device 23 is used for drying the sodium chloride salt to produce qualified sodium chloride dry salt.

Specifically, the acid making wastewater enters an evaporative crystallization device 21 to be concentrated to a sodium chloride crystallization point, sodium chloride salt begins to be separated out, then the sodium chloride salt is separated from mother liquor through a centrifugal device 22, then the sodium chloride salt is sent to a drying device 23 to be dried through hot air, qualified sodium chloride dry salt is produced, and the produced dry salt can reach the standard of industrial dry salt secondary products, can be sold as an industrial salt product, and is used for the printing and dyeing industry and the like. The condensed water evaporated by the evaporation crystallization device 21 can be returned to the sintering for use as the mixed water, and because of the condensed water, the salt content in the water is lower (the conductivity is less than 500mg/L), which is completely superior to the water quality requirement of the existing sintered mixed material.

In this embodiment, the evaporative crystallization device 21 includes, but is not limited to, an MVR evaporator, the centrifugation device 22 includes, but is not limited to, a centrifuge, and the drying device 23 includes, but is not limited to, a drying fluidized bed.

Because the acid making wastewater contains a certain amount of sulfate, in order to ensure the product quality of sodium chloride, a part of mother liquor (part of acid making wastewater) needs to be continuously discharged in a small flow, and the concentration of sodium sulfate in the MVR system is ensured to be less than the precipitation concentration of sodium sulfate, so that the quality of sodium chloride is ensured. Therefore, part of the acid making wastewater continuously discharged by the evaporative crystallization subsystem 20 can be treated by the bipolar membrane subsystem 30 to prepare acid liquid and alkali liquid, and the acid liquid and the alkali liquid can be used for other water treatment processes to adjust the pH value.

Further, the bipolar membrane subsystem 30 comprises, in serial communication:

the diluting device 31 is communicated with the evaporative crystallization subsystem 20 and receives part of acid making wastewater continuously discharged by the evaporative crystallization subsystem 20, and is used for adding industrial fresh water into the part of acid making wastewater for dilution;

a calcium and magnesium removing device 32 for removing calcium ions and magnesium ions in the part of the acid making wastewater;

and the bipolar membrane device 33 is used for treating part of acid making wastewater to prepare acid liquor and alkali liquor.

In the embodiment, through calculation, about 0.8-1.3% of the total amount of the acid-making wastewater is discharged per hour on average, so that the sodium sulfate can be ensured not to be separated out, the concentration of the mother liquor sodium sulfate is kept at about 10% and is far lower than the crystallization point of 40%, and the quality of a sodium chloride product is ensured.

In this embodiment, the discharged part of the acid making wastewater is first diluted with industrial water and cooled, the salt content is diluted to about 15%, and about 2.5 times of industrial fresh water is added. Then the effluent is introduced into chelating resin for calcium and magnesium ion removal to ensure that the calcium and magnesium ions in the effluent are lower than 0.5mg/L, and then the effluent is introduced into a bipolar membrane device 33, after the treatment of the bipolar membrane device 33, about 7.5% of sodium hydroxide and 7.5% of mixed acid (mainly hydrochloric acid and sulfuric acid) are produced, the total amount of the liquid alkali and the mixed acid is about 3.5% of the original water amount, the liquid alkali in the part can be used for adjusting the pH in the resin regeneration and other processes in the previous stage, and the consumption is easier due to the small amount.

Based on this, please refer to fig. 2, fig. 2 is a flowchart of the zero discharge treatment method for wastewater from activated coke flue gas purification acid production provided by the embodiment of the present invention, and the present application further provides a zero discharge treatment method for wastewater from activated coke flue gas purification acid production, which includes the following steps:

step S1: adding a defluorination agent into the acid making wastewater to perform chemical precipitation defluorination, then adding a flocculation agent into the acid making wastewater to perform flocculation precipitation, and then performing clarification precipitation to obtain high-salt clear water;

step S2: evaporating and crystallizing the high-salt clear water to obtain sodium chloride salt and condensed water, and then separating the sodium chloride salt from the high-salt clear water and drying the sodium chloride salt to produce qualified sodium chloride dry salt;

step S3: and receiving part of high-salt clear water continuously discharged by the evaporative crystallization subsystem, and processing the part of high-salt clear water to prepare acid liquor and alkali liquor.

The steps are performed in sequence, qualified sodium chloride dry salt is produced after the acid liquor wastewater is treated, the produced dry salt can reach the standard of an industrial dry salt secondary product and is sold as an industrial salt product for printing and dyeing industry and the like, the evaporated condensate water can be returned to sintering to be used as mixing water, and the condensate water has low salt content (the conductivity is less than 500mg/L) and is completely superior to the water quality requirement of the existing sintering mixing water. The prepared acid solution and alkali solution can be used for other water treatment processes to adjust the pH value.

Compared with other zero-emission processes, the whole process flow is relatively simple, the operation is convenient, and the investment is low. The process does not produce miscellaneous salt (most zero-discharge processes can produce a small amount of miscellaneous salt more or less), and the miscellaneous salt is recycled; meanwhile, a nanofiltration membrane salt separation process is not used, so that the replacement cost and the operation cost of a membrane element are reduced, the operation cost of the whole process is lower, the operation cost is about 50 yuan/ton of water, the income of salt selling products is not included, and the method has obvious cost advantage for other zero-discharge processes with hundreds of yuan/ton of water cost.

In this embodiment, the evaporative crystallization subsystem 20 continuously discharges the portion of the high-salt fresh water so that the concentration of sodium sulfate in the high-salt fresh water is lower than the crystallization point, thereby ensuring the quality of sodium chloride.

In this embodiment, the part of the high-salt clear water is 0.8% -1.3% of the total amount of the acid-making wastewater.

To sum up, the embodiment of the utility model provides an active burnt gas cleaning system acid waste water zero release processing system handles system acid waste water through removing fluorine subsystem earlier, can fall to below 20mg/L with water fluorine-containing, satisfies the technological requirement that gets into the evaporation crystallization subsystem, then passes through the evaporation crystallization subsystem carries out the evaporation crystallization, and output sodium chloride is meanwhile, receives through bipolar membrane subsystem evaporation crystallization subsystem lasts exhaust partial system acid waste water to the concentration of sodium sulfate is less than its crystallization point in the system acid waste water of assurance evaporation crystallization subsystem, thereby ensures the product quality of sodium chloride. In addition, the bipolar membrane subsystem is used for treating part of acid-making wastewater discharged by the evaporation crystallization subsystem to prepare acid liquid and alkali liquid, and the acid liquid and the alkali liquid can be used for other water treatment processes. The utility model provides an influence of system acid waste water to the follow-up process equipment corruption, finally reach the waste water zero release, realized waste water resourceization when the environmental protection.

The above description is only for the preferred embodiment of the present invention, and does not limit the present invention. Any technical personnel who belongs to the technical field, in the scope that does not deviate from the technical scheme of the utility model, to the technical scheme and the technical content that the utility model discloses expose do the change such as the equivalent replacement of any form or modification, all belong to the content that does not break away from the technical scheme of the utility model, still belong to within the scope of protection of the utility model.

Claims (10)

1. The utility model provides an active burnt gas cleaning system acid waste water zero release processing system which characterized in that includes:

the defluorination subsystem is used for removing fluoride ions in the acid-making wastewater:

the evaporative crystallization subsystem is communicated with the defluorination subsystem and is used for carrying out evaporative crystallization on the acid making wastewater to separate out a sodium chloride product;

and the bipolar membrane subsystem is communicated with the evaporation crystallization subsystem and receives part of acid making wastewater continuously discharged by the evaporation crystallization subsystem, and is used for treating the part of acid making wastewater to prepare acid liquid and alkali liquid.

2. The active coke flue gas purification acid making wastewater zero emission treatment system of claim 1, wherein the defluorination subsystem comprises, in serial communication:

the chemical precipitation fluorine removal device adopts a fluorine removal medicament to carry out chemical precipitation on the acid making wastewater so as to remove fluorine ions in the acid making wastewater;

the flocculation and precipitation device is used for carrying out flocculation and precipitation on the acid making wastewater by adopting a flocculation medicament so as to remove fluorine ions in the acid making wastewater;

and the clarification and precipitation device is used for clarifying and precipitating the acid making wastewater so as to separate suspended matters in the acid making wastewater from the acid making wastewater.

3. The system of claim 2, wherein the fluorine removal agent is sodium metaaluminate.

4. The activated coke oven gas purification acid making wastewater zero emission treatment system of claim 2, wherein the flocculating agent is polyacrylamide.

5. The active coke oven gas purification acid-making wastewater zero-emission treatment system of claim 1, wherein the evaporation crystallization subsystem comprises in serial communication:

the evaporative crystallization device is used for carrying out evaporative crystallization on the acid making wastewater to obtain sodium chloride salt and condensed water;

a centrifugal device for separating the sodium chloride salt from the acid-making wastewater;

and the drying device is used for drying the sodium chloride salt to produce qualified sodium chloride dry salt.

6. The active coke oven gas purification acid-making wastewater zero-emission treatment system of claim 5, wherein the evaporation crystallization device is an MVR evaporator.

7. The system of claim 5, wherein the drying device is a drying fluidized bed.

8. The system of claim 5, wherein the centrifuge is a centrifuge.

9. The active coke oven gas cleaning acid-making wastewater zero-emission treatment system of claim 1, wherein the bipolar membrane subsystem comprises, in serial communication:

the diluting device is communicated with the evaporative crystallization subsystem and receives part of acid making wastewater continuously discharged by the evaporative crystallization subsystem, and is used for adding industrial fresh water into the part of acid making wastewater for dilution;

the calcium and magnesium removing device is used for removing calcium ions and magnesium ions in the part of acid making wastewater;

and the bipolar membrane device is used for treating part of acid making wastewater to prepare acid liquor and alkali liquor.

10. The activated coke oven gas cleaning acid making wastewater zero emission treatment system of claim 9, wherein the calcium and magnesium removal device comprises chelating resin.

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