CN113413723B - Method for treating waste gas by using ion exchange resin - Google Patents

Abstract

The application relates to a method for treating waste gas by using ion exchange resin, including flue gas pretreatment-resin oxidation-desulfurization and denitrification-oxidant solution recycling, and using oxidant to convert common ion exchange resin into a form with oxidizing groups, so that common ions The exchange resin has both ion exchange function and strong oxidizing property. By intermittently spraying the regenerant, it can achieve non-stop production and non-stop production, and at the same time realize the oxidation, exchange and partial regeneration of the exchange resin, and has high-efficiency desulfurization and denitration performance.

Description

A kind of method that utilizes ion exchange resin to treat waste gas

technical field

The present application relates to the technical field of flue gas desulfurization and denitrification, and relates to a method for treating waste gas by using ion exchange resin, in particular to a method for purifying flue gas desulfurization and denitrification with ion exchange resin while partially regenerating.

Background technique

Industrial flue gas refers to the flue gas and dust produced by the combustion of industrial boilers. The main pollution factors in the flue gas of industrial boilers: sulfur dioxide (SO ₂ ), nitrogen oxides (NO _x ) and particulate matter, etc., are one of the main factors affecting the atmospheric environment, and SO ₂ , NO _x and particulate matter in the flue gas cannot reach the standard stably Emission of industrial boilers, effective control of sulfur dioxide and nitrogen oxides in industrial flue gas is the main problem in the industry.

At present, most of the small coal-fired boilers adopt the simple wet desulfurization and dust removal integration technology, the dust removal efficiency is about 90%, the desulfurization efficiency is about 50% (all use low-sulfur fuel), and the denitration efficiency is less than 10%. The flue gas purification technologies of large coal-fired boilers are mainly bag-type dust removal, sodium-alkali/calcium desulfurization, and selective catalytic reduction (SCR) desulfurization. The dust removal efficiency of the bag filter is high, reaching 99.8%; the desulfurizer is automatically added with desulfurizer, and the desulfurization efficiency reaches over 90%; the denitration efficiency of the SCR denitrification device is over 50% when it is put into operation, but due to the temperature window of the catalyst, it cannot be guaranteed Higher delivery rate.

Another problem is the regeneration process of the ion exchange resin. After the ion exchange resin is used for a period of time, the adsorbed impurities are close to the saturated state, so it is necessary to regenerate the ion exchange resin. Elution is removed to restore its original composition and properties. However, during the regeneration process, it is necessary to stop production and eluate the ion exchange resin separately, and the construction period is long, and one needs to be backed up and one used. At the same time, in the entire desulfurization and denitrification process, the entire process needs to be shut down, and the ion exchange resin is eluted and regenerated by chemical reagents alone, which is time-consuming and labor-intensive or starts with standby equipment, which requires a large investment and may affect Production safety, reducing process progress, resulting in different degrees of economic losses and negative impacts on environmental protection.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present application provides a method for simultaneous partial regeneration of ion exchange resin for purifying flue gas desulfurization and denitrification.

The present application provides a method for partial regeneration of ion exchange resin material by intermittent spraying. The specific steps are: intermittently spraying oxidant solution, passing through the ion exchange resin layer at a certain flow rate, and partially regenerating the ion exchange resin;

The time interval of the intermittent spraying is 4-72 hours, the spraying time is 4-8 min/time, and the spraying amount of the oxidant spraying solution is 1/4-1/6 of the resin volume dosage each time. The oxidant is one or more of K ₂ Cr ₂ O ₇ , NaClO, Ca(ClO) ₂ , NaClO ₂ , H ₂ O ₂ , and KMnO ₄ .

A method of utilizing an ion exchange resin to treat waste gas of the present application comprises the following steps:

Flue gas pretreatment - resin oxidation - desulfurization and denitrification - regeneration liquid recycling.

Flue gas pretreatment: The treatment includes the process of dust removal and cooling of flue gas;

Resin oxidation: intermittently spray the oxidant solution, the oxidant spray solution passes through the resin layer at a certain flow rate, so that the ion exchange resin becomes an oxidized ion exchange resin;

Desulfurization and denitrification: H ₂ SO ₄ , HNO ₃ and H ₂ SO ₃ , the oxidation products of SO2 and NO _x in the flue gas, are simultaneously adsorbed by the ion exchange resin to achieve simultaneous desulfurization and denitrification;

Solution recycling: The oxidant spray solution is recycled, and the waste liquid is recycled after regeneration.

The flue gas pretreatment includes the process of dedusting and cooling the flue gas. Generally, the exhaust temperature of boiler flue gas is about 120 ℃ ~ 180 ℃, and the adaptable temperature of ion exchange is below 60 ℃. Before entering the ion exchange material, the flue gas temperature needs to be reduced to 40-90 ℃, preferably 50-70 ℃ ℃, so that the ion exchange resin can reach the best use state during ion exchange, so that the removal rate can be increased. Optionally, the pretreatment of the industrial flue gas also includes dedusting treatment. Since there are a large number of dust particles in the industrial flue gas, the gaps in the resin layer will be blocked and covered on the anion exchange resin, thereby reducing the working exchange of the ion exchange resin. capacity, it is very easy to cause the desulfurization and denitrification effect in the subsequent process to decline.

In the flue gas cooling process, a flue gas-water heat exchanger can be used to reduce the temperature of the flue gas, and the water heated up after absorbing the heat of the flue gas is transported back to the boiler for use, which can greatly improve the thermal efficiency of the boiler. While reducing environmental pollution and protecting the environment, it can also generate certain economic benefits. Achieved "energy saving and environmental protection". The flue gas cooling process can also use a flue gas cooling system to achieve the same cooling effect.

According to at least one embodiment of the present application, the flue gas contains SO ₂ 500-2000 mg/m ³ before pretreatment, the NO concentration is 200-800 mg/m ³ , and the flue gas SO ₂ after being cooled by the flue gas heat exchanger and NO emission concentrations are less than 35mg/m ³ .

The ion exchange resin is a macroporous strong base or weak base anion exchange resin, and the anion resin is preferably a strong base anion exchange resin.

The ion exchange resin may be selected from styrenic resins and acrylic resins.

According to at least one embodiment, the anion exchange resin contains one of quaternary amino functional groups, secondary amino functional groups, primary amino functional groups or tertiary amino functional groups.

The anion exchange resin is selected from CO3 type strong base resin, OH type strong base resin, and preferably OH type strong base resin.

Specifically, one or more of commercially available D201SC resin, D309 resin, D301 resin, D301SC resin, D402 resin, SQD816 resin, and SQD817 resin can be used.

The resin oxidation process is to use a certain concentration of oxidant to spray the solution, pass through the resin layer at a certain flow rate, and the anions of the ion exchange resin undergo ion exchange reaction, so that the ion exchange resin becomes the form of an oxidant, so that the ion exchange resin has both ion exchange, oxidation.

The oxidant is K ₂ Cr ₂ O ₇ , NaClO, Ca(ClO) ₂ , NaClO ₂ , H ₂ O ₂ , KMnO ₄ and the like.

Compared with gas oxidant, liquid oxidant solution is preferred in the present application, and liquid oxidant of suitable concentration is configured by spraying, which can improve the efficiency of oxidation and ion exchange.

This application uses the basic principle of ion exchange to change the form of the exchange group of the ion exchange resin, so that the ion exchange resin not only becomes an "oxidant" with the effect of a strong oxidant, but also is an "ion exchanger" with an ion exchange function. When the gas passes through the resin layer, the SO ₂ and NO in the flue gas are first oxidized into nitrogen dioxide, nitrogen pentoxide and sulfur trioxide which are easily soluble in water, and then adsorbed by the ion exchange resin to achieve simultaneous desulfurization and denitrification. the goal of.

According to at least one embodiment, the strong base anion exchange resin has a strong base anion exchange group (-CH ₂ N-(CH ₃ ) ₃ Cl ^- ), and a common strong base anion exchange resin has exchangeable ions on the exchange group. It is chloride ion and has no oxidizing properties. The structure is as follows:

If a liquid oxidant solution of a certain concentration, taking NaClO solution as an example, passes through the resin layer at a certain flow rate, the ClO in the solution ^- that is, replaces Cl ^- transforms part of the resin into RClO:

RCl+NaClO→RClO+NaCl

The structural formula of RClO is as follows:

^The ClO adsorbed on the resin is unstable and still acts as a strong oxidant. Therefore, the transformed ion exchange resin has become the oxidant form.

According to actual needs, add a small amount of alkaline solution (for example, 1 wt%) to the liquid oxidant solution to adjust the pH value of the system. The oxidizing property of NaClO is extremely strong under acidic conditions (PH5-6), its oxidizing property is quickly exhausted, and the oxidation duration is short; It can maintain the oxidizing property for a long time. Therefore, in order to properly lengthen the oxidation time of NaClO to reduce unnecessary consumption, it is necessary to add an appropriate amount of lye to adjust the pH of the solution.

RCl+NaOH→ROH+NaCl

The alkali can be one or more of NaOH, KOH, NaHCO ₃ , Na ₂ CO ₃ , and ammonia water.

In the oxidant spray solution of the present application, based on the solution as 100%, the oxidant content is 0.3-4wt%, the alkali solution is 1-6wt%, and the rest is water.

Preferably, the oxidant spray solution of the present application has an oxidant content of 0.5-3 wt % and an alkali solution content of 1-4 wt %.

The present application adopts the method of intermittently spraying the liquid oxidant solution, the specific spraying interval is 4-72 hours, preferably 4-36 hours, and the solution spraying time is 4-8min/time.

The spraying amount of the oxidant spraying solution is 1/4-1/6 of the resin volume dosage each time.

According to the actual working conditions, if the concentration of SO ₂ and NO _x in the flue gas is high and the ion exchange resin material needs to be regenerated in time, the spraying time interval can be appropriately reduced, for example, 4-8 hours for spray regeneration of the ion exchange resin material. If the concentration of SO ₂ and NO _x in the flue gas is low, the spraying time interval can be appropriately extended, such as spraying and regenerating the resin for 1-3 days.

The resin oxidation process includes: oxidation reaction and hydration reaction of flue gas.

The oxidation reaction includes liquid oxidation reaction and solid oxidation reaction process.

The liquid oxidation reaction means that after the flue gas enters the ion exchange layer, SO ₂ and NO in the flue gas first undergo an oxidation reaction with the liquid NaClO carried on the surface of the ion exchange resin and in the crevices. SO ₂ and NO are oxidized to form SO ₃ and NO ₂ which are soluble in water; the reaction equation is as follows:

The solid-state oxidation reaction means that after the flue gas enters the ion _- exchange resin layer, the unreacted SO and NO in the flue gas continue to carry out oxidation reaction with the ion-exchange resin (RClO) that has become a "solid oxidant". , SO ₂ and NO in the flue gas are oxidized to form SO _{3 ,} NO ₂ and N ₂ O ₅ ;

The ion exchange resin after the redox reaction returns to the chlorine form (RCl) and still has the ion exchange capacity.

The hydration reaction means that SO ₃ , NO ₂ and N ₂ O ₅ generated after oxidation are rapidly dissolved in water and become H ₂ SO ₄ and HNO ₃ , part of SO ₂ that has not been oxidized, and an aqueous solution in the resin layer. A hydration reaction occurs to generate H ₂ SO ₃ .

The ion exchange reaction refers to that H ₂ SO ₄ , HNO ₃ and H ₂ SO ₃ generated after oxidation and hydration reactions are simultaneously adsorbed by the ion exchange resin to achieve the purpose of simultaneous desulfurization and denitration.

When the ion exchange resin runs for a long time, the saturated NaClO in the resin pores and the ClO ^- adsorbed on the resin exchange group will gradually decompose, causing unnecessary losses, and the oxidant may also decompose by itself. Therefore, part of the ion exchange resin is regenerated in time to avoid unnecessary loss of strong oxidants. The intermittent spraying of the present application can regenerate the resin in time, solve the above problems well, and improve the turnover rate and utilization rate of the ion exchange resin.

When the concentration of SO ₂ and NO in the flue gas exceeds the standard, it means that the ClO ^- on the resin is exhausted and has lost its oxidizing ability, and needs to be regenerated.

In the present application, by controlling the intermittent spraying method of the oxidant spraying solution, and adjusting the spraying time, interval time and frequency, the partial regeneration function of the resin can be realized at the same time.

Taking the oxidant solution NaClO+NaOH as an example, when the spray solution passes through the resin layer, part of the resin becomes RClO type again, which can continue to play the role of oxidizing SO ₂ and NO. The basic principle is as follows:

Conventional ion exchange process, the ion exchange process is to remove some ions, and the regeneration process uses a regenerant to elute some ions adsorbed on the resin, so the exchange and regeneration are completely opposite processes, and it is impossible to carry out at the same time. .

In the present application, by intermittently spraying the liquid oxidant solution, the regeneration and exchange of the resin can be carried out simultaneously. Since the oxidant is also a regenerant, it has a strong oxidizing effect on SO ₂ and NO in the flue gas. When the oxidant and the flue gas pass through the resin layer at the same time, the liquid oxidant will have a redox reaction with the SO ₂ and NO in the flue gas. Specifically, when the oxidant (ie the regenerant) and the flue gas enter the resin layer at the same time, since the concentration of the oxidant is nearly ten thousand times different from that of SO and NO in the flue gas, the resin first adsorbs the anions in the liquid oxidant such as ClO ^- , The RClO resin is formed to achieve partial regeneration of the resin. _{The regenerated resin has the functions of oxidation and ion exchange for SO 2 and} NO in the flue gas at the same time. redox reaction. (Take NaClO as an example):

NaClO+NO→NaCl+NO ₂

NaClO+2NO ₂ →NaCl+N ₂ O ₅

NaClO+SO ₂ →NaCl+SO ₃

In the conventional desulfurization and denitrification process, the ion exchange resin will fail in long-term operation, and the entire ion exchange resin needs to be shut down to replace or regenerate the ion exchange resin separately. The shutdown and shutdown will affect the operation cycle and operating cost, and the regeneration cycle generally takes 15-20 days.

In the present application, by intermittently spraying the oxidant for partial regeneration, it can achieve non-stop production and non-stop production, and at the same time satisfy the integration of exchange resin oxidation, exchange and regeneration. The performance and ion exchange performance are a major breakthrough in the current desulfurization and denitration process. It can realize partial regeneration of ion resin within one day, and the turnover rate and utilization rate of ion exchange resin are high; it not only saves construction period, uninterrupted production, but also can greatly reduce operation Cost, reduce the investment and land occupation of standby equipment, simplify the regeneration process, improve the resin utilization rate, reduce the resin usage, break the practice of shutdown regeneration, avoid the confusion of "one backup and one use" for equipment shutdown and regeneration during continuous operation, saving One-time investment.

In addition, because the liquid oxidant may have the problem of self-decomposition, if the overall regeneration, the ion exchange resin usage rate/saturation amount needs to reach 80%, if the time is too long, the ion exchange desulfurization and denitration ability will be weakened, and the ion resin utilization rate will be low. Therefore, this application Through intermittent spraying, part of the resin can be regenerated in time within one day, and the resin cannot be fully saturated, which improves the utilization rate and turnover rate of the resin.

According to at least one embodiment, the oxidant consumption of the partial regeneration of the resin of the present application is only half of that of the entire regeneration of the resin (conventional shutdown and regeneration process), which greatly reduces operating costs.

In addition, the desulfurization and denitrification process of the present application can also adjust the spray interval according to the use of the resin, the concentration of SO ₂ and NO in the flue gas, the effect of desulfurization and denitrification, etc., and the ion exchange resin can be sprayed for regeneration. For example, flue gas In the case of high concentrations of SO ₂ and NO _x in the flue gas, the spray interval is 4-8 hours shorter; when the concentrations of SO ₂ and NO _x in the flue gas are low, the spray interval is longer, such as 1-3 The resin is sprayed and regenerated every day.

According to at least one embodiment, the prepared oxidant solution is sent into the water distribution system of the ion exchange device to regenerate and transform the ion exchange material. The oxidant spray solution is sprayed every 4 hours for 6 minutes each time.

To sum up, in the intermittent spraying process of the present application, the oxidant spraying solution will have six reactions simultaneously in the ion exchange layer, SO ₂ is described as the representative ion:

(1) Liquid oxidation reaction

SO ₂ in the flue gas first undergoes an oxidation reaction with the liquid NaClO carried on the surface of the ion exchange material and in the gap:

(2) Resin solid-state oxidation reaction

_The unreacted SO2 in the flue gas continues the oxidation reaction with the ion exchange material (RClO) that has become a "solid oxidant":

(3) lye absorption reaction

Since the leaching liquid contains a small amount of NaOH, the residual SO ₂ is easily absorbed by the NaOH carried on the surface of the ion exchange material and in the crevices:

(4) Hydration reaction

The SO ₃ formed after oxidation dissolves rapidly in water and becomes H ₂ SO ₄ :

(5) Ion exchange reaction

The generated H ₂ SO ₄ is adsorbed by the ion exchange resin:

(6) Part of the ion exchange resin is regenerated and converted into RClO type:

The solution recycling refers to recycling the oxidant spray solution, recycling the waste liquid after regeneration, and preparing the oxidant spray again. After the leaching liquid passes through the resin layer, it is equivalent to regenerating part of the resin, and the discharged regeneration waste liquid contains a large amount of sulfate, sulfite, nitrate (Na ₂ SO ₄ , Na ₂ SO ₃ and NaNO ₃ ), In order to save water and reduce the amount of wastewater discharge, the discharged waste liquid passes through a ROH type ion exchange column, and a large amount of Na ₂ SO ₄ , Na ₂ SO ₃ and NaNO ₃ are adsorbed on the resin, and the treated alkaline All of the solution is recovered and used to prepare the oxidant spray solution again.

2ROH+Na ₂ SO ₄ →R ₂ SO ₄ +2NaOH

2ROH+Na ₂ SO ₃ →R ₂ SO ₃ +2NaOH

ROH+NaNO3 _{→ RNO3} +NaOH

In this process, if the ROH strong base type ion exchange column is saturated and needs to be regenerated, the regeneration of the ion exchange column can be used;

When the ROH strong base type ion exchange column is saturated, it is regenerated with a certain concentration of NaOH solution with twice the resin volume, the former regeneration waste liquid is discharged, and the latter regeneration waste liquid is kept for reuse in the next regeneration.

R ₂ SO ₄ +2NaOH→2ROH+Na ₂ SO ₄

R ₂ SO ₃ +2NaOH→2ROH+Na ₂ SO ₃

RNO ₃ +NaOH→ROH+NaNO ₃

The technical route features and beneficial effects of the present application are:

1. This application utilizes spraying oxidant solution to convert common ion exchange resin into a form with oxidizing groups, so that common ion exchange resin has both ion exchange function and strong oxidizing property.

2. During the operation of ion exchange resin desulfurization and denitrification in this application, the equipment does not need to be shut down to carry out the transformation and regeneration of the resin at the same time, which breaks the practice of shutdown and regeneration, and avoids the confusion of "one backup and one use" for equipment shutdown and regeneration during continuous operation. It saves one-time investment, realizes partial regeneration of resin within one day, and improves the utilization rate and turnover efficiency of ion exchange resin.

3. During the operation of the equipment, part of the ion exchange resin is regenerated in time, which improves the utilization rate of the resin and greatly reduces the usage of the resin and oxidant. It is verified by the experimental data of this application that the part of the resin regenerates its consumption of regenerant. It is only less than half of the overall regeneration of resin, which greatly reduces operating expenses.

4. In the form of intermittent spraying of oxidant solution, the application can achieve non-stop operation and non-stop production, and at the same time meet the integration of exchange resin oxidation, exchange and regeneration. When the resin exchange is saturated, intermittent spraying of oxidant solution can be achieved. The resin is partially regenerated, and has both oxidation performance and ion exchange performance at the same time, and has efficient desulfurization and denitration performance.

5. The process of the present application is not only suitable for processing low-temperature flue gas, but also does not need to heat up the low-temperature flue gas generated by the production process (consuming a large amount of thermal energy), and can directly enter the ion exchange device to achieve double low-concentration discharge; it can also be discharged from the production process. The high-temperature flue gas can also be recycled through the flue gas heat exchanger, which can also save a part of the energy.

6. This application adopts ion exchange resin for desulfurization and denitration. By preparing suitable oxidant spray liquid, not only the technical effect of desulfurization efficiency of 99.5% and denitration efficiency of more than 98% can be achieved, but also partial resin regeneration can be realized by controlling intermittent spray oxidant, Improve the efficiency of resin usage.

Description of drawings

The accompanying drawings illustrate exemplary embodiments of the application and, together with the description, serve to explain the principles of the application, are included to provide a further understanding of the application, and are included in and constitute the specification part of the manual.

Fig. 1 is the process flow diagram of embodiment 1

Among them, 101-spraying tank, 102-desulfurization and denitrification main equipment, 103-ion exchange column, 104-regeneration liquid reuse tank, 105-regeneration liquid configuration tank, 106-PH, ORP, TDS monitor

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the related content, rather than limit the application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings.

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other if there is no conflict. The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Example 1

Taking the unit equipment processing 10000m ³ /h flue gas as an example, the desulfurization and denitrification process flow is as follows:

1. Flue gas pretreatment: the concentration of SO ₂ in the flue gas is 500-2000 mg/m ³ , and the concentration of NO is 200-800 mg/m ³ , the induced draft fan is turned on, and the flue gas after cooling by the flue gas heat exchanger is 10,000 m ³ / The flow rate of h passes through the main equipment, and the emission concentrations of SO ₂ and NO in the treated flue gas are both <35mg/m ³ .

2. Spray oxidant solution: The composition of spray oxidant solution is 2.5% NaClO+1% NaOH.

About 3.5m ³ of oxidant solution is pre-prepared in the drenching tank; during the operation of the main equipment, the pump 1 and valve 1 are turned on to control the drenching flow rate of 16m ³ /h (the flow rate is about 2 times the volume of the D201SC anion exchange resin, and the dipping solution is about 2 times the volume of the D201SC anion exchange resin. The time is about 6 minutes, and the total amount of spray is 1.6m ³ , which is equivalent to 0.2 times the volume of resin.) After the spray is completed, close the pump 1 and valve 1. At this time, ClO in the leaching solution ^- that is, replaces the Cl ¹ - on the resin exchange group to transform the resin into RClO, and the ClO ^- adsorbed on the resin is unstable and still has the effect of a strong oxidant. Therefore, the transformed ion exchange resin has become a strong oxidant. When the flue gas containing SO ₂ and NO passes through the resin layer, the ClO adsorbed on the resin exchange group ^- that is, redox reaction occurs with SO ₂ and NO in the flue gas, and SO ₃ , NO ₂ and N are generated after oxidation. ₂ O ₅ quickly dissolves in water and becomes H ₂ SO ₄ and HNO ₃ . Part of SO ₂ that has not been oxidized also undergoes hydration reaction with the aqueous solution in the resin layer to form H ₂ SO ₃ .

The ion exchange resin after the redox reaction returns to the chlorine form (RCl) and still has the ion exchange capacity. The H ₂ SO ₃ , H ₂ SO ₄ and HNO ₃ in the resin layer are adsorbed by the ion exchange resin to achieve the purpose of desulfurization and denitration.

After 4 hours, turn on the pump 1 and valve 1 again, and intermittently spray the oxidant solution (the flow rate is about 2 times the resin volume, and the liquid spray time is about 6 minutes), and the anions in the oxidant such as ClO- and the ion exchange resin act to form RClO resin, Partial regeneration of the resin can be achieved. The regenerated resin has the functions of oxidation and ion exchange for SO ₂ and NO in the flue gas at the same time, realizing the redox of SO ₂ and NO in the flue gas while regenerating the ion exchange resin. reaction.

3. Recycling of leaching liquid: In order to make full use of the oxidant and lye in the leaching liquid, thereby reducing operating costs, the leaching liquid needs to be reused many times in actual production. The volume of the bottom box of the main equipment is about 5m ³ . When the liquid level at the bottom of the main equipment rises to the set position (observe the transparent liquid level gauge or take automatic liquid level control), turn on the pump 2 and valve 2, and pump the waste liquid into the In the spray tank, a new spray is configured according to the displayed values of PH, ORP and TDS (to achieve precise dosing and cost savings). When the liquid accumulation at the bottom of the main equipment drops to the set position, close the pump 2 and valve 2.

4. Liquid spray purification: In order to save water and reduce waste liquid discharge. When the drenching solution is reused 10 times, the drenching solution needs to be purified according to the TDS display value. Turn on pump 2, valve 3 and valve 4, control the flow rate to 2m ³ /h, pour the purified liquid into the drench tank, and configure a new drench according to the displayed values of PH, ORP and TDS. When the liquid accumulation at the bottom of the main equipment drops to the set position (observe the transparent liquid level gauge or take automatic liquid level control), close the pump 2, valve 3, and valve 4.

5. Regeneration of exchange column: When about 10m ³ of water is purified and recovered, the exchange column needs to be regenerated once. When regenerating, first use the recovery liquid in the recovery tank to regenerate. Open pump 3, valve 7, valve 9, valve 5, control the flow rate of 1m ³ /h, and discharge 0.5m ³ of regeneration waste liquid. When the regeneration and reuse liquid is used up, open valve 8, valve 6, close valve 5, Pour the regeneration liquid into the regeneration liquid reuse tank. When the configured regeneration liquid is used up, close the pump 3, valve 9 and valve 6. After the regeneration is completed, the exchange column is ready for use.

Example 2

The composition of the sprayed oxidant solution was 2% Ca(ClO) ₂ +1% NaOH, and other steps were the same as those in Example 1.

Example 3

The composition of the sprayed oxidant solution is: 1.2% NaClO ₂ +1% NaOH, and other steps are the same as in Example 1.

Example 4

The conditions for treating the flue gas were changed, and the oxidant and other steps were the same as in Example 1.

Example 5

The composition of the sprayed oxidant solution was 2% NaClO+2% NaHCO ₃ , and other steps were the same as those in Example 1.

Example 6

The composition of the sprayed oxidant solution was 3.5% KMnO ₄ +2% NaOH, and other steps were the same as in Example 1.

Example 7

The composition of the sprayed oxidant solution is 0.5% H ₂ O ₂ + 2% NaOH, and other steps are the same as in Example 1.

Comparative Example 1

1. Flue gas pretreatment: the concentration of SO ₂ in the flue gas is 500-2000 mg/m ³ , and the concentration of NO is 200-800 mg/m ³ , the induced draft fan is turned on, and the flue gas after cooling by the flue gas heat exchanger is 10,000 m ³ / The flow rate of h passes through the main equipment, and the emission concentrations of SO ₂ and NO in the treated flue gas are both <35mg/m ³ .

2. The common D201SC anion exchange resin is used to make the flue gas pass through the ion exchange resin. In the case of no oxidant spraying, it is necessary to stop the regeneration.

Comparative Example 2

D201SC anion exchange resin is used, gaseous oxidant is introduced, refer to CN111359409A (Anion exchange resin desulfurization and denitration method):

1. Flue gas pretreatment: the concentration of SO ₂ in the flue gas is 500-2000 mg/m ³ , and the concentration of NO is 200-800 mg/m ³ , the induced draft fan is turned on, and the flue gas after cooling by the flue gas heat exchanger is 10,000 m ³ / The flow rate of h passes through the main equipment, and the emission concentrations of SO ₂ and NO in the treated flue gas are both <35mg/m ³ .

2. Pressurize by a booster pump, inject the treated industrial flue gas into the gas mixing chamber, pass into ozone for reaction, control the mole ratio of ozone to nitric oxide to 1.5, make the gas oxidant pass through the ion exchange resin, and save Spray solution recovery step.

Comparative Example 3

1. Flue gas pretreatment: the concentration of SO ₂ in the flue gas is 500-2000 mg/m ³ , and the concentration of NO is 200-800 mg/m ³ , the induced draft fan is turned on, and the flue gas after cooling by the flue gas heat exchanger is 10,000 m ³ / The flow rate of h passes through the main equipment, and the emission concentrations of SO ₂ and NO in the treated flue gas are both <35mg/m ³ .

2. Spray oxidant solution: The composition of spray oxidant solution is 2.5% NaClO+1% NaOH.

Pre-prepared about 3.5m ³ of oxidant solution in the drenching tank; during the operation of the main equipment, open the pump 1, the valve 1 to control the leaching flow rate of 16m ³ /h (the flow rate is about 2 times the resin volume, and the leaching time is about 6 1.6m ³ in total, which is equivalent to 0.2 times the volume of resin), close the pump 1 and valve 1 after the drenching is completed.

The regeneration process adopts the whole shutdown regeneration, which is different from the intermittent spray regeneration in Example 1.

Table 1 embodiment and comparative example desulfurization and denitration process efficiency

Comparing the resin regeneration process of Example 1 and Comparative Example 1, it can be seen that the ion exchange resin of Example 1 of the present application can realize the functions of desulfurization and denitration, oxidation, exchange and partial regeneration by spraying the oxidant solution, and does not need to stop work. Production is stopped, and the amount of oxidant (ie, part of the regenerant) is less; Comparative Example 1 needs to be shut down for the overall regeneration of the resin, which not only consumes the construction period, but also requires backup equipment, which covers a large area, expensive investment costs, and high operating costs.

Through the investigation of the amount of regenerant in Example 1 and Comparative Example 3, it can be seen from Table 2 that in Comparative Example 3, the overall regeneration of the shutdown resin is used, and it is necessary to use a large amount of regenerant. Under the condition of the same amount of flue gas, the regeneration per unit time The consumption of the agent is too much; while the embodiment 1 adopts the method of intermittently spraying the regenerant without stopping, and in the case of realizing the same flue gas treatment amount and the time to reach the standard, the use amount of the oxidant (that is, part of the regenerant) in the embodiment 1 is only It is 0.2 times the volume of the resin, and the consumption of the regenerant per unit time is less, and the partial regeneration of the resin can save costs and reduce operating costs.

It can be seen from Example 1 and Comparative Example 2 that, compared with gaseous oxidants, liquid oxidants are preferred in the present application, and liquid oxidants of suitable concentrations are configured by spraying, which can improve the efficiency of oxidation and ion exchange, and the spraying operation is simple and low in cost. , the operating conditions are simple and easy to control; and the intermittent spraying can realize partial regeneration of the resin, eliminating the process of regenerating the resin, simplifying the process and reducing the production cost.

Table 2 Example 1 and comparative example 3 use of regenerant

R-resin volume in Table 2

This application adopts the process of liquid oxidant + ion exchange, and uses the basic principle of ion exchange to change the form of the exchange group of the ion exchange resin, so that the ion exchange resin is not only an "oxidant" with the effect of a strong oxidant, but also an "ion exchange resin". It has the function of ion exchange and achieves the purpose of simultaneous desulfurization and denitrification (the desulfurization efficiency reaches 99.5%, and the denitration efficiency exceeds 98%). Moreover, the oxidant of the present application also has the effect of a regenerating agent, which can partially regenerate the resin through intermittent spraying, and realize transformation at the same time, and at the same time meet the integrated process of exchange resin desulfurization, denitration, oxidation, exchange and regeneration, breaking the resin The practice of shutdown regeneration reduces the use of regenerant and saves one-time investment.

In the description of this specification, references to the terms "one embodiment/mode", "some embodiments/modes", "example", "specific example", or "some examples", etc. are intended to be combined with the description of the embodiment/mode A particular feature, structure, material, or characteristic described by way of example or example is included in at least one embodiment/mode or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment/mode or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments/means or examples. Furthermore, those skilled in the art may combine and combine the different embodiments/modes or examples described in this specification and the features of the different embodiments/modes or examples without conflicting each other.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless expressly and specifically defined otherwise.

It should be understood by those skilled in the art that the above embodiments are only for clearly illustrating the present disclosure, rather than limiting the scope of the present application. For those skilled in the art, other changes or modifications can also be made on the basis of the above disclosure, and these changes or modifications are still within the scope of the present application.

Claims (8)

1. a method utilizing ion exchange resin to process waste gas, is characterized in that, comprises the steps: Flue gas pretreatment: The treatment includes the process of dust removal and cooling of flue gas; Resin oxidation: intermittently spray the oxidant solution, the oxidant solution passes through the resin layer at a certain flow rate, so that the ion exchange resin becomes an oxidized ion exchange resin; intermittently sprays the oxidant solution, passes through the ion exchange resin layer at a certain flow rate, and partially regenerates ions exchange resin; The time interval of the intermittent spraying is 4-72 hours, the spraying time is 4-8min/time, and the spraying amount of the oxidant solution is 1/4-1/8 of the resin volume dosage each time; The ion exchange resin is a macroporous strong base anion exchange resin; The ion exchange resin contains one of a quaternary amino functional group, a secondary amino functional group, a primary amino functional group or a tertiary amino functional group; The exchangeable ion on the exchange group of the strong base anion exchange resin is chloride ion; The oxidant is NaClO; The resin oxidation step includes: oxidation reaction and hydration reaction of flue gas; The oxidation reaction of the flue gas includes a liquid oxidation reaction and a solid oxidation reaction process; The liquid oxidation reaction means that after the flue gas enters the ion exchange layer, SO ₂ and NO in the flue gas first undergo an oxidation reaction with the liquid NaClO carried on the surface of the ion exchange resin and in the gaps. SO ₂ and NO are oxidized to form SO ₃ and NO ₂ which are soluble in water; The solid-state oxidation reaction means that after the flue gas enters the ion exchange resin layer, the unreacted SO ₂ and NO in the flue gas continue to undergo oxidation reaction with the ion exchange resin that has become a "solid oxidant". SO ₂ and NO in are oxidized to generate SO _3, NO ₂ and N ₂ O ₅ ; The hydration reaction means that SO ₃ , NO ₂ and N ₂ O ₅ generated after oxidation are rapidly dissolved in water and become H ₂ SO ₄ and HNO ₃ , part of SO ₂ that has not been oxidized, and an aqueous solution in the resin layer. A hydration reaction occurs to generate H ₂ SO ₃ ; Desulfurization and denitrification: H ₂ SO ₄ , HNO ₃ and H ₂ SO ₃ , the oxidation products of SO ₂ and NO _x in the flue gas, are simultaneously adsorbed by the ion exchange resin to achieve simultaneous desulfurization and denitrification; Solution recycling: The oxidant solution is recycled, and the waste liquid is recycled after regeneration. 2 . The method according to claim 1 , wherein the flue gas pretreatment step is to use a flue gas cooling system to reduce the temperature of the flue gas to 40-90° C. 3 . 3 . The method according to claim 1 , wherein the flue gas pretreatment step is to use a flue gas-water heat exchanger to reduce the temperature of the flue gas to 40-90° C. 4 . 4. The method according to any one of claims 2 or 3, wherein the temperature reduction process of the flue gas pretreatment step is: reducing the temperature of the flue gas to 50-70°C. 5. method according to claim 1 is characterized in that, contains a certain amount of lye in oxidant solution, and the alkali in described lye is selected from NaOH, KOH, NaHCO ₃ , Na ₂ CO ₃ , a kind of ammoniacal liquor In the oxidant solution, calculated on the basis of 100% of the oxidant solution, the content of the oxidant is 0.3-4wt%, the content of the alkali solution is 1-6wt%, and the balance is water. 6 . The method according to claim 1 , wherein, after desulfurization and denitrification, the SO ₂ concentration of the flue gas is less than or equal to 35 mg/m ³ , and the NO _x concentration is less than or equal to 50 mg/m ³ . 7. method according to claim 1 is characterized in that, sulfate, sulfite, nitrate in the regeneration waste liquid are processed by the ion exchange column of ROH type, and alkaline solution is all recovered, and is used for preparing oxidant solution again . 8. method according to claim 1 is characterized in that, sulfate, sulfite, nitrate in the regeneration waste liquid are processed by ROH strong base type ion exchange column, after described ROH strong base type ion exchange column is saturated. , use a certain concentration of NaOH solution with twice the resin volume for regeneration, the former double regeneration waste liquid is discharged, and the latter double regeneration waste liquid is reserved for reuse in the next regeneration.

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