Water washing recycling and quality-based utilization system for fly ash

Abstract

The utility model discloses a water washing recycling quality-divided utilization system for fly ash, which comprises a sodium sulfate solid calcium section, a centrifugal machine and filter press combined dechlorination section and a fly ash water washing liquid quality-divided purification section, an inlet of a sodium sulfate dissolver is respectively connected with a secondary filtrate tank B and a concentrated liquid outlet of a sulfate radical remover; an inlet of the solid calcium and chlorine dissolving reactor is respectively connected with an outlet of the sodium sulfate dissolver and an outlet of the fly ash storage bin, and an outlet of the solid calcium and chlorine dissolving reactor is connected with a feeding hole of the first-stage centrifugal machine A. The water content of the washing ash is greatly reduced through the third-stage high-pressure filter press, and by integrating the solid calcium reducing and chlorine dissolving reactor, the calcium carbonate separator, the heavy metal remover and the sulfate radical remover, the recycling and quality-divided utilization of the fly ash is realized, the calcium fixing capacity of the washing fly ash is improved, and the utilization rate of a medicament and the water quality index of a purified washing liquid are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to solid waste treatment technical field especially is related to a fly ash's water washing resource utilization system of grading utilization. BACKGROUND

[0002] Compared with landfill, incineration can make the disposal of municipal solid waste more thoroughly, and waste incineration for power generation has become the best way to dispose of municipal solid waste. Fly ash, as a product of waste incineration for power generation, is designated as hazardous waste (code HW18) because it contains heavy metal inorganic harmful substances such as Cd, Cr, Cu, Ni, Pb and Zn, and also enriches organic carcinogens such as dioxins. At the same time, alkali metals and alkaline earth metal chlorides in municipal solid waste enter fly ash with flue gas in the high-temperature incineration process, resulting in high content of chlorides in incineration fly ash, increasing the leaching toxicity of heavy metals, and seriously affecting the safe disposal and resource utilization of fly ash. For example, in the process of harmless treatment and resource utilization of fly ash, chlorides will affect the strength of cement and aggregate; in the process of co-processing fly ash with a cement kiln, chlorides will react with limestone to produce adhesive substances, causing corrosion and skinning of the cement kiln wall. In addition, chlorides can also promote the volatilization of heavy metals at high temperatures. Therefore, desalination treatment of waste incineration fly ash is a prerequisite for the harmless and resource utilization of fly ash.

[0003] CN218555139U discloses a fly ash washing system, relating to the technical field of fly ash treatment and separation, which comprises a premixing part, a first-stage washing part, a second-stage washing part, a third-stage washing part and a water treatment system connected in sequence. The premixing part is used for mixing fly ash with water into fly ash slurry. The first-stage washing part is used for first-stage washing of the fly ash slurry to dissolve chloride ions and separate solids. The second-stage washing part is used for second-stage washing of the fly ash slurry to dissolve chloride ions and separate solids. The third-stage washing part is used for final washing of the fly ash slurry to make the finally produced wet fly ash and filtrate meet the treatment standard. The water treatment system is used for harmless treatment of waste liquid. The device does not need hot air drying, has small steam demand and does not need to rely on a cement kiln. Disadvantages: (1) The fly ash washing adopts a sequencing batch immersion washing process, the single-stage immersion washing time is greater than or equal to 1h, and the treatment efficiency is low; (2) The sequencing batch immersion washing process causes low working efficiency of a centrifugal machine and poor adaptability; (3) The washing system is provided with 15 tank bodies, has large occupied area, complex process, many maintenance points and high investment.

[0004] CN217912142U relates to a kind of waste incineration fly ash washing systems, including sequentially connected first-stage water washing barrel, horizontal screw centrifuge one, second-stage water washing barrel, horizontal screw centrifuge two, third-stage water washing barrel, horizontal screw centrifuge three, heavy metal leaching barrel, plate-and-frame filter press two, fourth-stage water washing barrel and horizontal screw centrifuge four;Wherein, the filtrate outlet of horizontal screw centrifuge one is communicated to plate-and-frame filter press one, the mud cake outlet of plate-and-frame filter press one is communicated to second-stage water washing barrel with the mud outlet of horizontal screw centrifuge one;The filtrate outlet of horizontal screw centrifuge two is communicated to first-stage water washing barrel, the filtrate outlet of horizontal screw centrifuge three is communicated to second-stage water washing barrel, and the filtrate outlet of horizontal screw centrifuge four is communicated to third-stage water washing barrel.The soluble chlorine content of washing fly ash is further reduced by using "three-stage washing+one-stage heavy metal leaching+one-stage washing", while the water ash ratio of fly ash washing is reduced, the water ash ratio can be 1.5:1, the operation load of water treatment and MVR (steam mechanical re-compression) system is reduced.Disadvantages: (1) three-stage washing+one-stage washing is used, and centrifuge is used in solid-liquid separation device, so the energy consumption is large, and the investment and operation cost are high;(2) although the water ash ratio is 1.5:1, because the number of washing times is increased, the water consumption per ton of ash is large, at the same time, the heavy metal reagent input amount in water treatment process is also increased, so the operation cost is increased;(3) the calcium ion content in primary filtrate is high, which is easy to cause the scaling of MVR (steam mechanical re-compression) evaporator equipment, and at the same time, the quality of chloride salt is affected. Practical new type content

[0005] In view of the deficiencies of the prior art, the utility model provides a kind of fly ash's washing resource utilization system of quality differentiation to solve the problems raised in the above background art, the utility model can be aimed at fly ash characteristics and end resource utilization path selection multistage alkaline washing, more conducive to realizing the resource utilization of fly ash;Double-alkali reagent dosing is used in washing liquid purification unit, to improve the calcium fixation capacity of washing fly ash;Sulfate removal device is set, to ensure the quality of chlorides;Process water is recycled, no wastewater and waste residue are generated, and no secondary pollution is generated.

[0006] In order to achieve the above-mentioned utility model purposes, the utility model provides a kind of fly ash's washing resource utilization system of quality differentiation.

[0007] The technical scheme of the utility model is a kind of fly ash's washing resource utilization system of quality differentiation, comprising: I sodium sulfate calcium fixation section, II fly ash washing liquid quality differentiation purification section, III centrifuge and filter press joint dechlorination section;

[0008] The I sodium sulfate calcium fixation section includes sequentially connected sodium sulfate dissolver, calcium fixation and chlorine dissolution reactor;

[0009] In the sodium sulfate calcium fixation section, the inlet of the sodium sulfate dissolver is connected with the secondary filtrate tank B and the sulfate remover concentrated liquid outlet respectively, the outlet of the sodium sulfate dissolver is connected with the inlet of the calcium fixation and chlorine dissolution reactor, and the outlet of the calcium fixation and chlorine dissolution reactor is connected with the feeding port of the primary centrifuge A.

[0010] The filtrate SS remover, the calcium carbonate extraction reactor, the calcium carbonate separator, the heavy metal extractor, the Ph adjuster, the sulfate remover, the evaporation raw water tank and the evaporation crystallization equipment are connected in sequence.

[0011] The inlet of the filtrate SS remover is connected with the outlet of the primary filtrate tank A, and the water washing liquid outlet of the filtrate SS remover is connected with the calcium carbonate extraction reactor, the calcium carbonate separator, the heavy metal extractor, the Ph adjuster, the sulfate remover and the evaporation raw water tank in sequence.

[0012] The primary centrifuge A, the secondary centrifuge A, the secondary centrifuge B, the tertiary high-pressure filter press, the secondary water washing tank, the tertiary water washing tank, the primary filtrate tank A, the secondary filtrate tank A, the secondary filtrate tank B and the tertiary filtrate tank are connected in the combined dechlorination section of the centrifuge and the filter press.

[0013] The feeding ports of the secondary water washing tank are connected with the solid phase outlets of the primary centrifuge A and the filtrate SS remover, the feeding ports of the tertiary water washing tank are connected with the solid phase outlets of the secondary centrifuge A and the secondary centrifuge B, the feeding port of the tertiary high-pressure filter press is connected with the discharging port of the tertiary water washing tank, and the discharging port of the tertiary high-pressure filter press is the output of the building material regeneration material.

[0014] Preferably, a dispersant adding pipeline is arranged on the pipeline from the primary filtrate tank A to the filtrate SS remover, and the filtrate SS remover is selected from any one of a plate and frame filter press, a vacuum belt filter and a membrane concentration device.

[0015] Preferably, a sodium carbonate adding pipeline is arranged in the calcium carbonate extraction reactor for secondary calcium fixation.

[0016] Preferably, the calcium carbonate separator and the heavy metal extractor are selected from any one of a plate and frame filter press and a vacuum belt filter.

[0017] Preferably, the water content of the fly ash filter cake produced by the tertiary high-pressure filter press is less than 15%.

[0018] Preferably, the backflow of the tertiary high-pressure filter press is connected to the secondary water washing tank.

[0019] Preferably, the processing capacity of the primary centrifuge A and the secondary centrifuge A is the same, and the processing capacity of the secondary centrifuge B is half of that of the primary centrifuge A.

[0020] The utility model discloses a system includes: sodium sulfate solid calcium, centrifuge and filter press combined dechlorination, fly ash washing liquid separate quality purification, three processes, the specific steps are as follows:

[0021] S1: ton bag ash pre-solution pulping: ton bag fly ash is sent into the unpacking machine through the forklift, after crushing and screening, into the solid calcium chlorine solution reactor, and sodium sulfate solution (the secondary water washing liquid and sodium sulfate configuration) is added according to the water-cement mass ratio 1.5-3:1 ratio to carry out premixing to obtain fly ash slurry, sodium sulfate is added in the solid calcium chlorine solution reactor and reacts with calcium ions in fly ash to generate calcium sulfate precipitate, that is, primary solid calcium, sodium sulfate solution is mixed with fly ash, and the reaction of sulfate and calcium ions generates precipitate, and the solid calcium rate reaches about 80%, and at the same time, the soluble chlorides in fly ash are dissolved into the water washing liquid.

[0022] S2: the fly ash slurry from the solid calcium chlorine solution reactor is fully stirred and dissolved, and the dissolved fly ash slurry enters the primary centrifuge A for solid-liquid separation, and the separated primary water washing ash enters the secondary water washing tank for second-stage elution and dissolution, and the separated water washing filtrate enters the primary filtrate tank;

[0023] The filtrate of the primary filtrate tank is transported to the filtrate SS remover, a dispersing agent is added in this process, and solid-liquid separation is carried out again by using the filtrate SS remover, and the dispersing agent is uniformly pulped in the secondary dissolution process of the solid phase. The solid containing the water washing ash after separation enters the secondary water washing tank, the filtrate after separation enters the calcium carbonate extraction reactor, and the water washing liquid SS amount after the treatment of the filtrate SS remover is less than 20mg / l;

[0024] S3: the primary water washing ash and the tertiary water washing filtrate from the tertiary filtrate tank are fully mixed in the secondary water washing tank for secondary water washing, the fly ash slurry from the secondary water washing tank enters the secondary centrifuge A for solid-liquid separation, the secondary water washing ash after separation enters the tertiary water washing tank for third-stage elution and dissolution, and the water washing filtrate after separation enters the secondary filtrate tank A;

[0025] The filtrate of the secondary filtrate tank A is transported to the secondary centrifuge B, a flocculating agent is added in this process, and solid-liquid separation is carried out by using the secondary centrifuge B, the solid containing the water washing ash after separation returns to the tertiary water washing tank, the filtrate after separation is transported to the secondary filtrate tank B, and the filtrate is transported to the sodium sulfate dissolver for pre-solution pulping;

[0026] S4: the secondary water washing ash and water are fully mixed in the tertiary water washing tank for tertiary water washing, the moisture content of the wet fly ash after high-pressure filter pressing is ≤15%, and the removal efficiency of soluble chloride ions reaches more than 99%; it is convenient for subsequent transportation and resource utilization, and the energy consumption of deep dewatering is reduced.

[0027] S5: The filtrate after step S2 enters a calcium carbonate extraction reactor to perform secondary calcium fixation and extract calcium carbonate with a purity higher than 98%, and then extract heavy metals to ensure that 95% of the heavy metals are recovered from the water washing liquid;

[0028] S6: The filtrate is then subjected to a neutralization reaction to adjust the pH to 6-7;

[0029] S7: The water washing liquid after the pH adjustment enters a sulfate remover, and the concentrated water containing a large amount of sulfate returns to a sodium sulfate dissolver; the concentrated liquid of the sulfate remover is reused for calcium fixation of fly ash, so that the amount of sodium sulfate per ton of fly ash can be reduced by 1-3%; the produced water is subjected to evaporation and crystallization, and the sulfate in the produced water of the sulfate remover is lower than 50 mg / l or higher, thereby ensuring the water quality for evaporation and the salt quality for crystallization.

[0030] Compared with the prior art, the utility model has the following advantages:

[0031] (1) The utility model can select multi-stage alkaline water washing according to the characteristics of fly ash and end resourceization path, and is more conducive to realizing resourceization utilization of fly ash.

[0032] (2) The solid-liquid separation technology combining the horizontal screw centrifuge and the plate and frame filter press improves the automation of the production line and greatly saves investment and operating cost.

[0033] (3) The water washing liquid purification unit adopts double-alkali reagent addition, improves the calcium fixation capacity of the water washing fly ash, and further reduces the operating cost.

[0034] (4) The filtration device is selected by adapting the membrane element, improves the quality of the water washing chlorides, and realizes stable and up-to-standard water washing chlorides as products.

[0035] (5) The whole process is water recycling, no wastewater and waste residue are generated, and no secondary pollution is generated. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The utility model discloses a process flow chart. DETAILED DESCRIPTION

[0037] The utility model will be described clearly and completely in combination with the drawings.

[0038] The embodiment is based on a kind of solid waste high-efficiency desalination equipment mainly including fly ash elution unit, water washing liquid purification unit and evaporation crystallization unit, as shown in figure 1. Figure 1 A fly ash water washing resourceization and quality utilization system, comprising: I sodium sulfate calcium fixation section, II fly ash water washing liquid quality purification section, III centrifuge and filter press combined dechlorination section;

[0039] The sodium sulfate solid calcium section includes a sodium sulfate dissolver, a solid calcium chlorine dissolving reactor connected in sequence;

[0040] In the sodium sulfate solid calcium section, the inlet of the sodium sulfate dissolver is connected with the secondary filtrate tank B and the sulfate remover concentrated liquid outlet respectively, the outlet of the sodium sulfate dissolver is connected with the fly ash storage outlet and the inlet of the solid calcium chlorine dissolving reactor, and the outlet of the solid calcium chlorine dissolving reactor is connected with the feeding port of the primary centrifuge A.

[0041] The fly ash water washing liquid quality purification section II includes a filtrate SS remover, a calcium carbonate extraction reactor, a calcium carbonate separator, a heavy metal extractor, a Ph adjuster, a sulfate remover, an evaporation raw water tank and an evaporation crystallization device.

[0042] The inlet of the filtrate SS remover is connected with the outlet of the primary filtrate tank A, and the water washing liquid outlet of the filtrate SS remover is connected with the calcium carbonate extraction reactor, the calcium carbonate separator, the heavy metal extractor, the Ph adjuster, the sulfate remover and the evaporation raw water tank in sequence.

[0043] The centrifuge and filter press combined dechlorination section III includes a primary centrifuge A, a secondary centrifuge A, a secondary centrifuge B, a tertiary high-pressure filter press, a secondary water washing tank, a tertiary water washing tank, a primary filtrate tank A, a secondary filtrate tank A, a secondary filtrate tank B and a tertiary filtrate tank.

[0044] The feeding ports of the secondary water washing tank are connected with the solid phase outlets of the primary centrifuge A and the filtrate SS remover respectively, the feeding ports of the tertiary water washing tank are connected with the solid phase outlets of the secondary centrifuge A and the secondary centrifuge B respectively, the feeding port of the tertiary high-pressure filter press is connected with the discharging port of the tertiary water washing tank, and the discharging port of the tertiary high-pressure filter press is the building material regeneration material output.

[0045] In the embodiment, a dispersant adding pipeline is arranged on the pipeline from the primary filtrate tank A to the filtrate SS remover, and the filtrate SS remover is selected from any one of a plate and frame filter press, a vacuum belt filter and a membrane concentration device.

[0046] In the embodiment, a sodium carbonate adding pipeline is arranged in the calcium carbonate extraction reactor for secondary solid calcium.

[0047] In the embodiment, the calcium carbonate separator and the heavy metal extractor are selected from any one of a plate and frame filter press and a vacuum belt filter.

[0048] In the embodiment, the fly ash filter cake produced by the tertiary high-pressure filter press has a water content of less than 15%.

[0049] In the embodiment, the backflow of the tertiary high-pressure filter press is connected to the secondary water washing tank.

[0050] In the embodiment, the processing capacity of the primary centrifuge A and the secondary centrifuge A is the same, and the processing capacity of the secondary centrifuge B is half of that of the primary centrifuge A.

[0051] The utility model discloses a system, which comprises three processes of sodium sulfate solidification, centrifuge and filter press combined dechlorination and fly ash washing liquid purification, and the specific steps are as follows:

[0052] S1: ton bag ash pre-solution pulping: ton bag fly ash is sent into a bale breaker by a forklift, and after crushing and screening, the fly ash is introduced into a calcium solidification and chlorine dissolution reactor, and sodium sulfate solution (second-stage washing liquid and sodium sulfate) is added in a proportion of 1.5-3:1 to the fly ash to obtain fly ash slurry, and in the calcium solidification and chlorine dissolution reactor, sodium sulfate reacts with calcium ions in the fly ash to generate calcium sulfate precipitate, i.e., primary calcium solidification, and the sodium sulfate solution is mixed with the fly ash, and the sulfate ions and calcium ions react to generate precipitate, and the calcium solidification rate reaches about 80%, and at the same time, the soluble chlorides in the fly ash are dissolved into the washing liquid.

[0053] S2: the fly ash slurry from the calcium solidification and chlorine dissolution reactor is fully stirred and dissolved, the dissolved fly ash slurry is introduced into a primary centrifuge A for solid-liquid separation, and the primary washing ash after separation is introduced into a secondary washing tank for second-stage elution and dissolution, and the washing filtrate after separation is introduced into a primary filtrate tank;

[0054] The filtrate of the primary filtrate tank is transported to a filtrate SS remover, a dispersing agent is added in the process, and the filtrate is separated again by using the filtrate SS remover, and the dispersing agent is uniformly dissolved in the solid phase in the secondary dissolution process. The solid containing washing ash after separation is introduced into a secondary washing tank, the filtrate after separation is introduced into a calcium carbonate extraction reactor, and the washing liquid SS amount after treatment by the filtrate SS remover is less than 20 mg / l;

[0055] S3: the primary washing ash and the third-stage washing filtrate from a third-stage filtrate tank are fully mixed in the secondary washing tank for secondary washing, the fly ash slurry from the secondary washing tank is introduced into a secondary centrifuge A for solid-liquid separation, the secondary washing ash after separation is introduced into a third-stage washing tank for third-stage elution and dissolution, and the washing filtrate after separation is introduced into a secondary filtrate tank A;

[0056] The filtrate of the secondary filtrate tank A is transported to a secondary centrifuge B, a flocculating agent is added in the process, and the filtrate is separated by using the secondary centrifuge B, the solid containing washing ash after separation is returned to the third-stage washing tank, the filtrate after separation is transported to a secondary filtrate tank B, and the filtrate is transported to a sodium sulfate dissolver for pre-solution pulping;

[0057] S4: The secondary water washing ash and water are fully mixed in the third water washing tank for third water washing, and after high-pressure filter pressing, the moisture content of the wet fly ash is less than or equal to 15%, and the removal efficiency of soluble chloride ions is more than 99%; the subsequent transportation and resource utilization are facilitated, and the energy consumption of deep dewatering is reduced.

[0058] S5: The filtrate separated in step S2 enters a calcium carbonate extraction reactor for secondary calcium fixation and extraction of calcium carbonate with a purity higher than 98%, and then heavy metals are extracted to ensure that 95% of the heavy metals are recovered from the water washing liquid;

[0059] S6: Then the filtrate is subjected to a neutralization reaction to adjust the pH to 6-7;

[0060] S7: The water washing liquid after the pH adjustment enters a sulfate remover, and the concentrated water containing a large amount of sulfate returns to a sodium sulfate dissolver; the concentrated liquid of the sulfate remover is reused for calcium fixation of fly ash, so that the amount of sodium sulfate per ton of fly ash can be reduced by 1-3%; the produced water is subjected to evaporation and crystallization, and the sulfate in the produced water of the sulfate remover is less than 50mg / l or higher, thereby ensuring the water quality of evaporation and the quality of crystalline salt.

[0061] The above shows and describes the basic principles and main features of the present application and the advantages of the present application, and for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0062] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments that those skilled in the art can understand.

Claims

1. A fly ash water washing resource utilization system with quality separation, characterized in that, The application relates to a fly ash water washing liquid purification device. The sodium sulfate solid calcium section comprises a sodium sulfate dissolver and a solid calcium chlorine dissolving reactor connected in sequence. The fly ash water washing liquid purification section comprises a filter liquid SS remover, a calcium carbonate extraction reactor, a calcium carbonate separator, a heavy metal extractor, a Ph regulator, a sulfate remover, an evaporation raw water tank and an evaporation crystallization device. The filter liquid SS remover is connected with the outlet of the first filter liquid tank A. The centrifuge and filter press combined dechlorination section comprises a first centrifuge A, a second centrifuge A, a second centrifuge B, a third high-pressure filter press, a second water washing tank, a third water washing tank, a first filter liquid tank A, a second filter liquid tank A, a second filter liquid tank B and a third filter liquid tank. The feed inlet of the second water washing tank is connected with the discharge outlet of the first centrifuge A and the solid phase outlet of the filter liquid SS remover. The sodium carbonate adding pipeline is arranged in the calcium carbonate extraction reactor for secondary solid calcium.

2. The fly ash water washing resource utilization system according to claim 1, characterized in that, The calcium carbonate separator and the heavy metal extractor are selected from any one of a plate frame and a vacuum belt filter.

3. The fly ash water washing resource recovery and fraction utilization system according to claim 1, characterized in that, The fly ash filter cake produced by the third high-pressure filter press has a water content of less than 15%.

4. The fly ash water washing resource recovery and fraction utilization system according to claim 1, characterized in that, The backflow of the third high-pressure filter press is connected to the second water washing tank.

5. The fly ash water washing resource recovery and fraction utilization system according to claim 1, characterized in that, The processing capacity of the first centrifuge A and the second centrifuge A is the same, and the processing capacity of the second centrifuge B is half of that of the first centrifuge A.

6. The fly ash water washing resource recovery and fraction utilization system according to claim 1, characterized in that, ​ 7. The fly ash water washing resource recovery and fraction utilization system according to claim 1, characterized in that, ​

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