CN116173730A - Desulfurization liquid zero discharge method - Google Patents
Desulfurization liquid zero discharge method Download PDFInfo
- Publication number
- CN116173730A CN116173730A CN202310337310.1A CN202310337310A CN116173730A CN 116173730 A CN116173730 A CN 116173730A CN 202310337310 A CN202310337310 A CN 202310337310A CN 116173730 A CN116173730 A CN 116173730A
- Authority
- CN
- China
- Prior art keywords
- desulfurization
- slurry
- chlorine
- island
- dialysis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/96—Regeneration, reactivation or recycling of reactants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/0082—Regulation; Control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
- B01D1/30—Accessories for evaporators ; Constructional details thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/73—After-treatment of removed components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/025—Reverse osmosis; Hyperfiltration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/08—Apparatus therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
- B01D61/10—Accessories; Auxiliary operations
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/02—Crystallisation from solutions
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Water Supply & Treatment (AREA)
- Nanotechnology (AREA)
- General Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Environmental & Geological Engineering (AREA)
- Biomedical Technology (AREA)
- Sustainable Development (AREA)
- Crystallography & Structural Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention discloses a desulfurization liquid zero discharge method which comprises the following steps: combining raw flue gas in the desulfurization island with a desulfurization reagent to generate desulfurization slurry; a bypass connected in parallel with the desulfurization island is established outside the desulfurization island, and part of desulfurization slurry is continuously led out; the led desulfurization slurry is subjected to chlorine dialysis to obtain dialysis slurry and chlorine-enriched produced water; the dialysis slurry flows back to the desulfurization island and is desulfurized in the desulfurization island; concentrating the chlorine-rich produced water or/and evaporating to dryness and crystallize. According to the scheme, chloride ions in the desulfurization slurry are directly discharged out of the desulfurization island along with the chlorine-rich produced water, and the balance of the internal chloride ions is maintained after the desulfurization island is supplemented with water. The chlorine-rich produced water only contains a small amount of sulfate radical and calcium magnesium hardness ions while taking away the chloride ions, and further has a small scaling trend due to concentration and decrement by a back-end process, so that the conversion efficiency and effect of sulfur dioxide into gypsum are ensured, and meanwhile, the cost is reduced and the process is simplified.
Description
Technical Field
The invention relates to the field of environmental protection, in particular to a zero discharge method of desulfurization liquid of flue gas.
Background
Flue gas desulfurization devices have been commonly installed in the thermal power industry. The limestone-gypsum Wet Flue Gas Desulfurization (WFGD) technology has a series of advantages of wide application range of coal types, high desulfurization efficiency and the like, and becomes the leading technology of domestic and foreign flue gas desulfurization. In the wet desulfurization and flue gas washing process, flue gas fly ash is washed and enters limestone-gypsum slurry, harmful substances such as chloride ions, heavy metal ions and the like contained in the flue gas fly ash also enter a flue gas desulfurization system, and in the gypsum treatment process, the flue gas fly ash enters a desulfurization wastewater link along with flushing water, so that desulfurization slurry rich in heavy metal and chloride ions is formed.
At present, most of desulfurization waste water of power plants is directly discharged after conventional treatment, and the conventional desulfurization waste water treatment mainly adopts a triple box process of three steps of neutralization, reaction and flocculation treatment, and finally the waste water containing more salt substances is discharged. The waste water contains more cations such as calcium, magnesium, copper, iron, manganese and the like and Cl - 、SO 4 2- Plasma anions, although marginally capable of reaching standard emissions, are often discharged directlyThe water body causes serious pollution. Only a few domestic power plants are forced to realize zero emission of desulfurization wastewater due to special reasons, and the advanced desulfurization wastewater treatment technology is still in a fumbling stage, which can be called a factory, and the desulfurization wastewater generated by the existing flue gas treatment method can be concentrated, reduced and evaporated to realize zero liquid emission of wastewater.
The desulfurization slurry is subjected to desulfurization treatment to obtain solid gypsum, and desulfurization wastewater is generated. Cl in the desulfurization wastewater - From flue gas, limestone and make-up water, chlorine elements contained in the coal are converted into HCl after being combusted in a boiler furnace, the HCl is absorbed by desulfurization slurry, the limestone is ground into fine powder as an absorbent, and chlorine elements, heavy metals and the like are quickly dissolved out in a slurry pool.
Cl in the desulfurization wastewater - And sulfate radical are above 10000mg/L, and contain high-concentration calcium-magnesium hardness ions, which means that the calcium sulfate of the water is in a saturated state. In order to achieve the aim of zero emission of wastewater, the wastewater is required to be concentrated and then evaporated to dryness for crystallization, and a reverse osmosis membrane component is mostly adopted for the concentration treatment; in the concentration process of the reverse osmosis membrane component, saturated calcium sulfate is quickly separated out and scales on the reverse osmosis membrane, so that the reverse osmosis membrane is blocked, and the concentration treatment cannot be normally performed. Therefore, a two-alkali process is usually adopted to remove hardness ions in the desulfurization wastewater before concentration, so as to reduce the scaling tendency of calcium sulfate in the pre-concentration section of the desulfurization wastewater.
However, the two-alkali process for removing the hard requires adding a large amount of liquid alkali, lime, sodium carbonate and other medicaments, has high dosing cost and simultaneously generates a large amount of chemical sludge. If the direct precipitation would require a longer residence time, there may be problems with large floor space of the precipitation tank and frequent mud run out; if the membrane process such as tube ultrafiltration is used for separating mud from water, additional energy costs are incurred. The final sludge is further subjected to plate and frame filter pressing and then is transported and treated, so that sludge disposal cost is generated.
Therefore, how to reduce the cost of zero liquid discharge in the desulfurization industry of power plants is one of the important technical problems that a person skilled in the art needs to solve.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention aims to provide a desulfurization liquid zero-emission system for flue gas and a desulfurization liquid zero-emission method thereof.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a desulfurization liquid zero release method comprises the following steps:
combining raw flue gas in the desulfurization island with a desulfurization reagent to generate desulfurization slurry;
a bypass for continuously leading out part of the desulfurization slurry is established outside the desulfurization island;
the led desulfurization slurry is subjected to chlorine dialysis to obtain dialysis slurry and chlorine-enriched produced water;
the dialysis slurry flows back to the desulfurization island for circulating desulfurization;
concentrating the chlorine-rich produced water or/and evaporating to dryness and crystallize.
Further preferred is: the bypass is arranged in parallel with the desulfurization inner circulation of the desulfurization island.
Further preferred is: divalent ions in the desulfurization slurry are intercepted by chlorine dialysis, and monovalent ions in the desulfurization slurry are dialyzed, so that chlorine-rich produced water is continuously discharged outside the desulfurization island.
Further preferred is: and the dialysis slurry flows back into the desulfurization island and is converged into the desulfurization slurry for circulating desulfurization.
Further preferred is: the chloride ion content of the desulfurization slurry is less than 20000mg/L.
Further preferred is: the concentration is reverse osmosis concentration.
Further preferred is: and evaporating and crystallizing to obtain the bypass flue evaporation.
After the technical scheme is adopted, compared with the background technology, the invention has the following advantages:
according to the zero discharge method of the desulfurization liquid, a bypass is added on a circulating desulfurization path in a desulfurization island, the bypass is communicated with the circulating desulfurization path, and the desulfurization slurry in the desulfurization island is led out for chlorine dialysis, so that chlorine ions are continuously discharged out of the desulfurization island along with dialysis water, and meanwhile, the residual slurry after dialysis is led back into the desulfurization island for circulating desulfurization, after the desulfurization island is supplemented with water, the concentration of the chlorine ions in the desulfurization island is ensured to be controlled below 20000mg/L all the time, divalent ions are still contained in the dialysis slurry, the divalent ions do not need to be concentrated and evaporated to be crystallized in the prior art, the circulating desulfurization in the desulfurization island is realized, the scaling phenomenon of second-order ions on a membrane used for concentration is avoided, and the process is simplified, and the cost is greatly reduced; in addition, the chlorine-rich produced water obtained through dialysis can be concentrated or/and evaporated to dryness for crystallization to obtain solid materials, so that the purpose of zero discharge of liquid is achieved.
Drawings
FIG. 1 is a process flow diagram of a flue gas desulfurization liquid zero release system according to an embodiment of the present invention;
fig. 2 is a process flow diagram of the desulfurization liquid zero-discharge system provided in the comparative example in the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
It should be noted that, in the present invention, terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are all based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element of the present invention must have a specific orientation, and thus should not be construed as limiting the present invention.
Examples
As shown in fig. 1, the desulfurization liquid zero-emission system is used for the purpose of liquid zero emission of waste gas treatment in a thermal power plant, realizes direct treatment operation on desulfurization slurry in a desulfurization island, improves the solidification treatment effect of the desulfurization island, and simultaneously can realize the purpose of liquid zero emission.
The desulfurization liquid zero-emission system can remove a large amount of chloride ions in desulfurization slurry, and has the following structure:
the desulfurization liquid zero-emission system comprises a desulfurization island and an external system which are sequentially connected, wherein the external system comprises a chlorine dialysis unit, a decrement unit and a drying unit.
In the desulfurization liquid zero-emission system provided by the invention, the desulfurization island comprises a limestone pulping tank, a limestone-gypsum flue gas desulfurization tower and a clarification tank;
the limestone pulping tank is used for preparing limestone slurry, a limestone powder feeding port, a water inlet and a slurry outlet are formed in the limestone pulping tank, and a stirring device is preferably arranged in the limestone pulping tank;
the limestone-gypsum flue gas desulfurization tower is reaction equipment for flue gas desulfurization and gypsum generation, an original flue gas inlet is arranged on the side wall of a tower kettle, a clean flue gas outlet is arranged at the top of the tower, a circulating slurry outlet, a gypsum slurry outlet and an air inlet are arranged at the bottom of the tower, the circulating slurry outlet is connected with the liquid inlet end of a slurry circulating pipeline of the desulfurization tower, the liquid outlet end of the slurry circulating pipeline is connected with a slurry spraying device arranged at the top of the inner cavity of the desulfurization tower, the air inlet is connected with an oxidation fan matched with the slurry outlet, and the gypsum slurry outlet is connected with a clarification tank. It should be noted that: and a slurry outlet is formed in the side wall of the limestone-gypsum flue gas desulfurization tower and is connected with the chlorine dialysis unit and used for guiding out desulfurization slurry, and the slurry outlet is positioned on the slurry reflux path.
The clarifier is equipment for settling gypsum slurry, and the clarifier is provided with a gypsum slurry inlet and a clear liquid outlet, wherein the gypsum slurry inlet is communicated with the gypsum slurry outlet of the limestone-gypsum flue gas desulfurization tower and is used for introducing the gypsum slurry into the clarifier, and the clear liquid outlet is communicated with a clear liquid reflux port arranged on the limestone-gypsum flue gas desulfurization tower to realize the reflux of clear liquid.
The waste gas enters a limestone-gypsum flue gas desulfurization tower from an original flue gas inlet and is in countercurrent contact with slurry sprayed from the tower top; in the countercurrent contact process, the slurry absorbs sulfur dioxide in the original flue gas, then falls into the bottom of the tower, and the desulfurized clean flue gas is discharged from a clean flue gas outlet at the top of the tower; reacting the slurry falling into the bottom of the tower with air blown into the tower through an air inlet to oxidize calcium sulfite in the slurry into gypsum; part of tower bottom slurry is sent to the tower top through a slurry circulation pipeline and is sprayed out again, and the other part of tower bottom slurry is discharged through a gypsum slurry outlet arranged at the tower bottom and is led into a clarifier for precipitation, clear liquid of the clarifier flows back into a limestone-gypsum flue gas desulfurization tower, and the following steps are needed: the slurry at the bottom of the tower is delivered to the tower top through a slurry circulation pipeline and is sprayed again, and then part of sprayed slurry is led out through a slurry outlet and is discharged into a chlorine dialysis unit. It should be noted that: the desulfurization slurry is slurry for circularly absorbing sulfur dioxide flue gas in a flue gas desulfurization tower by a limestone-gypsum method, and mainly contains solid calcium sulfate, calcium hydroxide, calcium carbonate components, ionic high-concentration calcium ions, magnesium ions, sulfate ions, chloride ions, partial metal ions and the like. That is to say: according to the technical scheme, the chlorine dialysis treatment is carried out on the mixture of the solid object and the liquid slurry, so that the chlorine dialysis treatment is carried out on the part of the extracted desulfurization slurry on the basis of the internal circulation of the desulfurization slurry in the limestone-gypsum flue gas desulfurization tower, the dechlorination slurry is discharged back into the limestone-gypsum flue gas desulfurization tower, the internal circulation desulfurization operation is continued, and the concentration of chloride ions in the desulfurization slurry in the limestone-gypsum flue gas desulfurization tower is ensured to be basically stable after the desulfurization island is supplemented with water.
In the desulfurization liquid zero-emission system provided by the invention, the chlorine dialysis unit is nanofiltration dialysis equipment and is used for separating chloride ions in the desulfurization slurry, and the chlorine dialysis unit is separated into a concentrated water side and a water production side by utilizing a nanofiltration dialysis membrane; the concentrated water side of the chlorine dialysis unit is provided with an inlet and a reflux outlet, and the inlet is communicated with the slurry outlet of the limestone-gypsum flue gas desulfurization tower and is used for introducing desulfurization slurry into the concentrated water side of the chlorine dialysis unit; the water producing side of the chlorine dialysis unit is provided with a separation outlet which is communicated with the reverse osmosis decrement unit. The reflux outlet is communicated with the limestone-gypsum flue gas desulfurization tower, slurry on the concentrated water side is led into the limestone-gypsum flue gas desulfurization tower for circulating spraying treatment, the separation outlet is communicated with the decrement unit, and the water producing side of the decrement unit is subjected to subsequent concentration and decrement treatment. The desulfurization slurry is continuously led into the concentrated water side of the chlorine dialysis unit from the limestone-gypsum flue gas desulfurization tower, a large amount of chloride ions enter the water producing side of the desulfurization slurry along with the permeate liquid through the nanofiltration dialysis membrane, and a large amount of chloride ions in the desulfurization slurry are dialyzed and taken out, and the following needs to be described: the chlorine-enriched produced water which is led into the water producing side by dialysis contains a large amount of chloride ions, and almost no sulfate radical and calcium magnesium hardness ions which cause calcium sulfate scaling, thereby achieving the purposes of removing chlorine by dialysis and ensuring that the back-end decrement unit does not scale.
The nanofiltration dialysis membrane is a membrane group which can tolerate high suspended matters (the suspended matters content is 10-15%), and can intercept most of second-order ions such as calcium, magnesium and sulfate ions and permeate most of monovalent ions such as chloride ions at the same time, so that the chloride ions are discharged out of the desulfurization island. The nanofiltration dialysis membrane is a flat membrane component. Meanwhile, the internal circulation of the desulfurization island flushes the surface of the membrane at a large flow rate, and at the same time, calcium sulfate possibly generated on the surface of the membrane can be scaled on the generated instant stripping surface of the membrane at a very high membrane surface flow rate, so that the long-term stability of the membrane performance is realized.
Preferably: the concentrated water outlet of the chlorine dialysis unit is provided with a pressure regulating valve, the opening of the pipeline is dynamically controlled by the pressure regulating valve, when the dialysis equipment works, the opening of the valve is regulated down, and the pressure in front of the valve (namely, the working pressure required by chlorine dialysis in the nanofiltration dialysis equipment) can be suppressed to about 8-10 Bar; when the nanofiltration dialysis equipment is stopped, the opening of the valve is fully opened, and the nanofiltration dialysis equipment is depressurized.
In the desulfurization liquid zero-emission system provided by the invention, the decrement unit is reverse osmosis equipment, two sides of a membrane arranged in the decrement unit are divided into a concentrated water side and a water producing side by the decrement unit, the chlorine dialysis unit is communicated with the concentrated water side of the decrement unit, the concentrated water side is communicated with the water producing side by a reverse osmosis membrane, and the pressure is applied to the concentrated water side, so that the concentrated water side is reverse-osmosis into the water producing side, the concentration of the concentrated water side is improved, and the decrement and concentration effects are achieved, namely: and introducing chlorine-rich produced water containing a large amount of chloride ions from the chlorine dialysis unit to the concentrated water side of the decrement unit, and continuously increasing the chloride ions on the concentrated water side for concentration by utilizing the reverse osmosis action in the decrement unit to obtain chlorine-rich concentrated water. It should be noted that: the reverse osmosis membrane is a sea-pale grade reverse osmosis membrane, the rejection rate of sodium chloride is over 99 percent, the concentration multiple is determined by the actual water quality, and the water quantity after concentration is required to be matched with the treatment capacity of a rear-end evaporation crystallization unit.
In the desulfurization liquid zero-emission system provided by the invention, the decrement unit is communicated with the drying unit, and specifically: the concentrated water side of the decrement unit is communicated with the drying unit. The drying unit is a drying crystallization device, and the drying crystallization device is used for drying and crystallizing chlorine-rich concentrated water with high concentration by evaporation, so that the chlorine-rich concentrated water is led into an evaporation zone of the drying unit for drying and crystallizing, thereby realizing drying treatment of concentrated solution and avoiding liquid discharge of the concentrated water.
In the desulfurization liquid zero-emission system provided by the invention, the drying unit is a drying crystallization device, the drying crystallization device is any device for realizing liquid drying and crystallization, and the device is any one of an effective forced circulation evaporation system (MED), a falling film mechanical vapor compression evaporation system (MVC), a vapor mechanical recompression evaporation (MVR) or a bypass flue evaporation system; in this embodiment, the evaporation and drying crystallization apparatus is illustrated by taking a bypass flue evaporation system as an example, but is not limited to the bypass flue evaporation system.
In this embodiment, the drying unit is a bypass flue evaporation system, and is that a small amount of flue gas extracted from the upstream of the air preheater passes through a spray drying tower, and the chlorine-rich concentrated water is pumped into the spray drying tower through a water pump to be mixed with the hot flue gas of the boiler. The flow of the flue gas needed by the spray drying tower is controlled through the baffle door, so that a set flow field is formed in the spray drying tower, fine liquid particles passing through the nozzle are mixed with hot flue gas, the chlorine-rich concentrated water is fully evaporated due to the large contact specific surface area, and the temperature of the hot flue gas is reduced and controlled to be higher than the acid dew point or the air expected outlet temperature, so that no condensation or evaporation of liquid entrainment occurs before the flue gas enters the dust remover. The desulfurization waste water containing soluble and suspended solid particles is evaporated at high temperature flue gas. Heavy metal ions and other ions in the chlorine-rich concentrated water can be crystallized and separated out, and evaporated solid entrainment is collected into a downstream electric dust collector and mixed into whole plant fly ash for centralized treatment.
It should be noted that: the desulfurization liquid zero-emission system comprises a desulfurization island and an external system which are sequentially connected, wherein the external system comprises a chlorine dialysis unit, a decrement unit and a drying unit. The reduction unit can be omitted under the condition that the water yield of the chlorine-rich water is less and the drying unit can only be used for realizing the evaporation and crystallization. The specific method is as follows: the decrement unit can be omitted under the condition that the water yield of the chlorine-rich water and the evaporation capacity of the evaporation mode are matched.
In the desulfurization liquid zero-emission system provided by the invention, the water on the water production side of the decrement unit is recycled, and the recycling refers to water supplementing of other process sections of the power plant or a desulfurization island.
The invention also provides a desulfurization liquid zero-emission process method, which is carried out in the desulfurization liquid zero-emission system according to the technical scheme, and comprises the following steps:
guiding out desulfurization slurry in the desulfurization island, preparing limestone slurry from limestone powder in a limestone pulping pond, and then conveying the limestone slurry serving as a desulfurization absorbent into a limestone-gypsum flue gas desulfurization tower; the waste gas enters a limestone-gypsum flue gas desulfurization tower from an original flue gas inlet and is in countercurrent contact with slurry sprayed from the tower top; in the countercurrent contact process, the slurry absorbs sulfur dioxide in the original flue gas, then falls into the bottom of the tower, and the desulfurized clean flue gas is discharged from a clean flue gas outlet at the top of the tower; reacting the slurry falling into the bottom of the tower with air blown into the tower through an air inlet to oxidize calcium sulfite in the slurry into gypsum; a part of the bottom slurry is sent to the tower top through a slurry circulation pipeline and is sprayed again, and the other part of the bottom slurry is discharged through a gypsum slurry outlet arranged at the tower bottom;
the slurry discharged from the gypsum slurry outlet enters a clarification tank for precipitation to obtain clear liquid, and the clear liquid flows back into a desulfurization island for desulfurization operation;
meanwhile, the slurry circularly sprayed in the limestone-gypsum flue gas desulfurization tower is discharged from a slurry outlet at the side of the limestone-gypsum flue gas desulfurization tower, the discharged slurry is desulfurization slurry, and the desulfurization slurry is continuously introduced into a communicated chlorine dialysis unit for chlorine dialysis treatment, namely: the desulfurization slurry enters a chlorine dialysis unit for separation to obtain dialysis slurry and chlorine-enriched produced water respectively;
the dialysis slurry is discharged through a reflux outlet of the chlorine dialysis unit, enters the desulfurization island, and is converged into the desulfurization slurry in the desulfurization island to continue circulating desulfurization operation;
the chlorine-rich produced water is discharged through a separation outlet of the chlorine dialysis unit and enters the decrement unit for concentration, so that chlorine-rich concentrated water and concentrated produced water are respectively obtained;
the concentrated produced water is recycled;
and discharging the chlorine-rich concentrated water through a concentrated water outlet of the deweighting unit, and entering the drying unit for evaporating and crystallizing to obtain a solid chlorine-rich product.
Under the condition that the water yield of the chlorine-enriched water and the evaporation capacity of the evaporation mode are matched, the decrement unit can be omitted, namely: the invention also provides a desulfurization liquid zero-emission process method, which comprises the following steps:
limestone powder is prepared into limestone slurry in a limestone pulping tank, and the limestone slurry is then conveyed into a limestone-gypsum flue gas desulfurization tower as a desulfurization absorbent; the waste gas enters a limestone-gypsum flue gas desulfurization tower from an original flue gas inlet and is in countercurrent contact with slurry sprayed from the tower top; in the countercurrent contact process, the slurry absorbs sulfur dioxide in the original flue gas, then falls into the bottom of the tower, and the desulfurized clean flue gas is discharged from a clean flue gas outlet at the top of the tower; reacting the slurry falling into the bottom of the tower with air blown into the tower through an air inlet to oxidize calcium sulfite in the slurry into gypsum; a part of the bottom slurry is sent to the tower top through a slurry circulation pipeline and is sprayed again, and the other part of the bottom slurry is discharged through a gypsum slurry outlet arranged at the tower bottom;
the slurry discharged from the gypsum slurry outlet enters a clarification tank for precipitation to obtain clear liquid, and the clear liquid flows back into a desulfurization island for desulfurization operation;
meanwhile, the slurry circularly sprayed in the limestone-gypsum flue gas desulfurization tower is discharged from a slurry outlet at the side of the limestone-gypsum flue gas desulfurization tower, the discharged slurry is desulfurization slurry, the desulfurization slurry is introduced into a communicated chlorine dialysis unit for chlorine dialysis treatment, and the chlorine dialysis treatment comprises the following steps: the desulfurization slurry enters a chlorine dialysis unit for separation to obtain dialysis slurry and chlorine-enriched produced water respectively;
the dialysis slurry is discharged through a reflux outlet of the chlorine dialysis unit, enters the desulfurization island, and is converged into the desulfurization slurry in the desulfurization island to continue circulating desulfurization operation;
and discharging the chlorine-rich produced water through a separation outlet of the chlorine dialysis unit, and feeding the chlorine-rich produced water into a drying unit for evaporating and crystallizing to obtain a solid chlorine-rich product.
The evaporated crystallization can be performed by adopting a bypass flue for evaporation, but is not limited to the bypass flue for evaporation. The bypass flue evaporates into a small amount of flue gas extracted from the upstream of the air preheater, and the flue gas passes through a spray drying tower, and the chlorine-rich concentrated water is pumped into the spray drying tower through a water pump to be mixed with the hot flue gas of the boiler. The flow of the flue gas needed by the spray drying tower is controlled through the baffle door, so that a set flow field is formed in the spray drying tower, fine liquid particles passing through the nozzle are mixed with hot flue gas, the chlorine-rich concentrated water is fully evaporated due to the large contact specific surface area, and the temperature of the hot flue gas is reduced and controlled to be higher than the acid dew point or the air expected outlet temperature, so that no condensation or evaporation of liquid entrainment occurs before the flue gas enters the dust remover. The desulfurization waste water containing soluble and suspended solid particles is evaporated at high temperature flue gas. Heavy metal ions and other ions in the chlorine-rich concentrated water can be crystallized and separated out, and evaporated solid entrainment is collected into a downstream electric dust collector and mixed into whole plant fly ash to be treated together in a concentrated way.
According to the technical scheme provided by the invention, from the reduction of the concentration of chloride ions in the desulfurization slurry, an independent bypass is connected in parallel outside the desulfurization island, the desulfurization slurry is continuously led out, the desulfurization slurry is subjected to chlorine dialysis treatment to obtain dialysis slurry, the dialysis slurry intercepts the original second-order ions, and dialyzes monovalent ions, so that the concentration of the chloride ions in the dialysis slurry is reduced, the low-chlorine dialysis slurry flows back into the desulfurization island to carry out circulating desulfurization, the concentration of the chloride ions in the desulfurization island is kept below 20000mg/L, the concentration of the chloride ions in the desulfurization tower can be controlled at a lower level, and then the desulfurization system can be operated normally under the condition of low concentration of the chloride ions, namely, the desulfurization system in the desulfurization island is operated at a high concentration multiplying power, and the influence of scale formation on desulfurization operation is obviously reduced while high-efficiency desulfurization operation treatment is realized.
In addition, in the preferable technical scheme provided by the invention, the desulfurization concentrated water is directly supplied by using the circulating pump in the desulfurization island, so that the equipment investment is reduced, meanwhile, the space occupied by the equipment is reduced, and the equipment investment cost and the occupied area cost are further reduced; the external connection system, namely the bypass connected in parallel outside the desulfurization island, can directly utilize the circulating pump of the circulating pipeline to provide partial pressure required by chloride ions to permeate the membrane, so that the energy consumption of the whole chlorine dialysis process is reduced, and the surface of the membrane is continuously flushed under the high-flow circulation of desulfurization slurry, so that the scaling trend of the surface of the membrane is reduced, and the membrane pollution is delayed.
Comparative example
(1) This comparative example provides a desulfurization wastewater zero release system comprising: the device comprises a desulfurization island (the desulfurization island comprises a limestone pulping tank, a limestone-gypsum flue gas desulfurization tower and a clarification tank), a pretreatment unit (the pretreatment unit comprises a dosing and hardness removal three-header and a mud-water separation unit), a reduction unit and a drying unit; the tower bottom is provided with a circulating slurry outlet, a gypsum slurry outlet and an air inlet, the circulating slurry outlet is connected with a liquid inlet end of a slurry circulating pipeline of the desulfurizing tower, a liquid outlet end of the slurry circulating pipeline is connected with a slurry spraying device arranged at the top of an inner cavity of the desulfurizing tower, and the air inlet is connected with an oxidation fan matched with the slurry spraying device; the gypsum slurry separation equipment specifically selects a gypsum cyclone; the gypsum dehydration equipment specifically selects a vacuum belt conveyor; the wastewater separation equipment specifically selects a wastewater cyclone; the dosing and hardness removing triple box specifically comprises a neutralization tank, a reaction tank and a flocculation tank which are arranged in series; the specific connection relationship between the devices is shown in fig. 2, and will not be described herein.
(2) The comparative example also provides a process method for carrying out zero emission of desulfurization wastewater in the system, which comprises the following steps:
limestone powder is prepared into limestone slurry in a limestone pulping tank, and the limestone slurry is then conveyed into a limestone-gypsum flue gas desulfurization tower as a desulfurization absorbent;
the waste gas enters a limestone-gypsum flue gas desulfurization tower from an original flue gas inlet and is in countercurrent contact with slurry sprayed from the tower top; in the countercurrent contact process, the slurry absorbs sulfur dioxide in the original flue gas, then falls into the bottom of the tower, and the desulfurized clean flue gas is discharged from a clean flue gas outlet at the top of the tower; reacting the slurry falling into the bottom of the tower with air blown into the tower through an air inlet to oxidize calcium sulfite in the slurry into gypsum; delivering one part of the tower bottom slurry to the tower top through a slurry circulation pipeline for re-spraying, and discharging the other part of the tower bottom slurry through a gypsum slurry outlet arranged at the tower bottom;
the slurry discharged from the gypsum slurry outlet enters a clarification tank for precipitation to obtain desulfurization wastewater;
the desulfurization wastewater contains chloride ions and sulfate radicals which are more than 10000mg/L and also contains high-concentration calcium magnesium hardness ions, which means that: the calcium sulfate in the desulfurization wastewater is in a saturated state, and is directly led into reverse osmosis equipment, so that scaling of the calcium sulfate is extremely serious, and effective reduction treatment cannot be achieved, and therefore, hard removal pretreatment is needed before concentration.
The desulfurization wastewater enters a dosing and hardness removal triple box, liquid alkali is added into the dosing and hardness removal triple box to adjust the pH value to be alkaline (namely, the pH value is 11) so as to enable magnesium ions to generate magnesium hydroxide sediment, bicarbonate in the magnesium hydroxide sediment is converted into carbonate radicals to react with calcium to generate calcium carbonate sediment, and then sodium carbonate is added to further enable the rest calcium ions to generate calcium carbonate sediment;
the slurry which is added with the medicine and generates the solid sediment enters a mud-water separation unit for sedimentation to obtain clear liquid; it should be noted that: the mud-water separation unit is usually a tubular ultrafiltration or a sedimentation tank, the sedimentation tank has the problems of large occupied area and mud leakage, the tubular ultrafiltration has the problems of relatively high investment and operation cost, and the mud needs to be further subjected to plate-frame filter pressing and then is transported outwards for treatment, so that the treatment cost of the mud is generated;
the clear liquid enters a decrement unit for decrement treatment, and concentrated produced water is recycled; the decrement unit is reverse osmosis equipment;
the decrement unit is a concentrated water drying unit which is eliminated by the evaporation equipment, and evaporation drying crystallization is carried out.
Therefore, in the comparative example, a plurality of devices are needed to be connected for the treatment of desulfurization wastewater, the aim of realizing the treatment for a plurality of times to reach the standard of zero emission of desulfurization liquid is obviously achieved, the problems of large equipment investment, high cost, high operation and maintenance cost and the like are obviously solved, the technical scheme set forth in the embodiment directly separates chloride ions from desulfurization slurry, and simultaneously, cations such as calcium, magnesium and anions such as sulfate radical are remained in the desulfurization slurry for circulation desulfurization, so that desulfurization operation can be carried out on the desulfurization slurry in a low-chloride ion environment, meanwhile, the separated off-stream drainage scaling tendency containing the chloride ions is greatly reduced, the reduction can be directly carried out by reverse osmosis equipment or the waste water enters a bypass flue for evaporation, the adding medicine for hardness removal and the subsequent mud-water separation process are omitted, and the economy of the whole process is improved while the process is simplified; also note that: the original circulating pump in the desulfurization island is utilized to provide the pressure required by the chloride ions to permeate the membrane for the external unit, so that the energy consumption caused by the external high-pressure pump is further reduced, and the surface of the membrane is continuously flushed under the large-flow circulation of desulfurization slurry, so that the scaling trend of the surface of the membrane is reduced, the membrane pollution is delayed, and the method has the remarkable effects of reducing the cost and improving the efficiency.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (7)
1. The desulfurization liquid zero release method is characterized in that: the method comprises the following steps:
combining raw flue gas in the desulfurization island with a desulfurization reagent to generate desulfurization slurry;
a bypass for continuously leading out part of the desulfurization slurry is established outside the desulfurization island;
the led desulfurization slurry is subjected to chlorine dialysis to obtain dialysis slurry and chlorine-enriched produced water;
the dialysis slurry flows back to the desulfurization island for circulating desulfurization;
concentrating the chlorine-rich produced water or/and evaporating to dryness and crystallize.
2. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: the bypass is arranged in parallel with the desulfurization inner circulation of the desulfurization island.
3. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: divalent ions in the desulfurization slurry are intercepted by chlorine dialysis, and monovalent ions in the desulfurization slurry are dialyzed, so that chlorine-rich produced water is continuously discharged outside the desulfurization island.
4. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: and the dialysis slurry flows back into the desulfurization island and is converged into the desulfurization slurry for circulating desulfurization.
5. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: the chloride ion content of the desulfurization slurry is less than 20000mg/L.
6. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: the concentration is reverse osmosis concentration.
7. The desulfurization liquid zero-discharge method according to claim 1, characterized in that: and evaporating and crystallizing to obtain the bypass flue evaporation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310337310.1A CN116173730A (en) | 2023-03-31 | 2023-03-31 | Desulfurization liquid zero discharge method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310337310.1A CN116173730A (en) | 2023-03-31 | 2023-03-31 | Desulfurization liquid zero discharge method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116173730A true CN116173730A (en) | 2023-05-30 |
Family
ID=86449060
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310337310.1A Pending CN116173730A (en) | 2023-03-31 | 2023-03-31 | Desulfurization liquid zero discharge method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116173730A (en) |
-
2023
- 2023-03-31 CN CN202310337310.1A patent/CN116173730A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4687649A (en) | Flue gas desulfurization process | |
| CN105948364B (en) | A kind of desulfurization wastewater zero-discharge treatment system based on bypass flue evaporation | |
| CN105481157A (en) | Method for zero emission treatment of desulfurization waste water based on flue gas waste heat evaporation | |
| CN107082523A (en) | A kind of wet desulphurization waste water reclaiming processing system and its processing method | |
| CN105254101A (en) | Desulfurization waste water zero-discharging treatment technology for coal-fired power plants | |
| CN205676302U (en) | A kind of based on fume afterheat evaporation desulfurization wastewater zero-discharge treatment system | |
| CN105621776B (en) | A kind of processing method of fire coal boiler fume wet desulphurization waste water | |
| CN101891330A (en) | Power plant wastewater treatment system and method | |
| CN106430786A (en) | Desulfurization wastewater treating method and device | |
| CN107758962A (en) | A kind of system of the preparing magnesium sulfate from desulfurization wastewater | |
| CN106492615B (en) | Desulfurization method and desulfurization system for coal-fired flue gas | |
| CN111423046A (en) | Power plant desulfurization wastewater advanced treatment and resource utilization system and method | |
| CN111233239A (en) | Zero-discharge process and system for resource utilization of desulfurization wastewater | |
| CN205556349U (en) | Novel zero release of desulfurization waste water is handled device | |
| CN106517628A (en) | Desulfurization-wastewater zero discharging device for coal-fired power plant | |
| CN205575837U (en) | Processing system of lime stone / lime - gypsum method flue gas desulfurization waste water | |
| CN115893559A (en) | Desulfurization wastewater zero-discharge system and desulfurization wastewater zero-discharge process | |
| CN206476848U (en) | A kind of desulfurization wastewater zero-discharge treatment system | |
| CN105621775A (en) | Novel desulfurated wastewater zero-emission treatment device and method | |
| CN112441601A (en) | System and method for extracting magnesium sulfate and sodium chloride from desulfurization wastewater | |
| CN219489757U (en) | Desulfurization waste water treatment device for coal-fired power plant | |
| CN219489796U (en) | Desulfurization liquid zero release system | |
| CN216572431U (en) | Wet flue gas desulfurization system | |
| CN208732818U (en) | A kind of Desulphurization for Coal-fired Power Plant Wastewater zero-discharge treatment system | |
| CN116173730A (en) | Desulfurization liquid zero discharge method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |