Cement kiln bypass discharged air chlorine ash removal washing resource utilization method

Abstract

The invention discloses a water-washing resource utilization method for removing chlorine ash through bypass exhaust of a cement kiln. The water-washing resource utilization method comprises the following steps: 1) removing chlorine ash from the cement kiln; 2) feeding the dechlorinated ash into a premixing tank for premixing; (3) pumping the premixed slurry into a first-stage washing tank, stirring and cleaning; 4) pumping the slurry in the first-stage washing tank into first-stage centrifugal equipment, and carrying out solid-liquid separation; (5) feeding the solid ash separated in the step (4) into a secondary washing tank, stirring and cleaning; 6) pumping the slurry in the second-stage washing tank into second-stage plate and frame equipment, and carrying out solid-liquid separation; (7) treating the water separated in the step (4) in a decalcification reaction tank; and (8) feeding the purified salt-containing water into an evaporation system, and separating out sodium chloride and potassium chloride. The content of chloride ions in the cement clinker is reduced, the cost of cement raw materials is saved, the cost of treatment except chlorine ash is reduced, and the resource utilization of potassium chloride and sodium chloride can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of cement clinker production lines, and particularly relates to a method for resource utilization of chlorine-removing ash water washing from bypass air extraction of a cement kiln. Background Art

[0002] In the process of implementing the present invention, the inventors found that the prior art has at least the following problems:

[0003] In the process of cement clinker production, chloride ions and alkali metals will circulate and accumulate in the cement kiln firing system, affecting the stable operation of the cement kiln and also the quality of the clinker. In the standard GB / T 21372-2024 "Portland Cement Clinker", it is required that the chloride ion content of the cement clinker ≤ 0.06%, and the content of alkali metals (Na2O + 0.658K2O) ≤ 0.6%.

[0004] With the use of alternative fuels in the cement kiln and the co-disposal of solid and hazardous wastes, the amount of chloride ions and alkali metals input into the cement kiln increases. To ensure the stable operation of the cement kiln and the quality of the clinker, a bypass air extraction system is generally added to the cement kiln. A certain amount of high-temperature air is extracted from the flue gas chamber part with a higher concentration of chloride ions and alkali metals in the cement kiln to discharge part of the chloride ions and alkali metals from the cement kiln system. The chlorine-removing ash collected by the bypass air extraction system contains a high content of chloride ions and alkali metals.

[0005] CN113003964A - A continuous water washing and chlorine removal device for fly ash from waste incineration discloses a continuous water washing and chlorine removal device for fly ash from waste incineration. The device includes a chlorine removal device unit, and the device unit includes a main body, a sleeve, a mixing area partition, a water outlet weir, a stirrer, a fly ash feed pipe, a cleaning liquid inlet pipe, and a slurry lifting pipe. The device successively includes a vertical flow ash-water precipitation area, an ash-water rising area, an ash-water mixing and chlorine removal area, and a slurry concentration area from top to bottom. It realizes continuous fly ash cleaning, fly ash ash-water separation, and the transportation of slurry and wastewater in one cleaning device, and cannot solve the above technical problems either. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for resource utilization of chlorine-removing ash water washing from bypass air extraction of a cement kiln, which reduces the chloride ion content in the cement clinker, saves the cost of cement raw materials, reduces the cost of outsourcing the disposal of chlorine-removing ash, and can also realize the resource utilization of potassium chloride and sodium chloride.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: A method for resource utilization of chlorine-removing ash water washing from bypass air extraction of a cement kiln, including the following steps:

[0008] 1) The cement kiln produces chlorine-removing ash;

[0009] 2) The chlorine-removing ash enters the premixing tank for premixing;

[0010] 3) The premixed slurry is pumped into the first - stage water - washing tank for stirring and cleaning;

[0011] 4) The slurry in the first - stage water - washing tank is pumped into the first - stage centrifugal equipment for solid - liquid separation;

[0012] 5) The solid ash separated in step (4) enters the second - stage water - washing tank for stirring and cleaning;

[0013] 6) The slurry in the second - stage water - washing tank is pumped into the second - stage plate - and - frame equipment for solid - liquid separation;

[0014] 7) The water separated in step (4) is treated in the de - calcification reaction tank;

[0015] 8) The purified brine enters the evaporation system to separate sodium chloride and potassium chloride.

[0016] In the above step (1), when the cement kiln is operating and the chloride ion and alkali content in the system reach the set values, the hot air in the smoke chamber part is extracted, so that the chloride ions and alkali metals are carried out of the kiln system with the hot air, and then through rapid cooling, cyclone, and dust removal treatment, the chlorine - removed ash is obtained.

[0017] In the above step (1), the chlorine - removed ash contains 15 - 40% chloride ions, 10 - 25% potassium oxide, 0 - 5% sodium oxide; other components include calcium oxide, silicon dioxide, aluminum oxide, and iron oxide.

[0018] In the above step (2), after the chlorine - removed ash is metered and regulated, it first enters the premixing tank and is premixed with the water filtered by the second - stage plate - and - frame to control the water - to - ash ratio at 1:3. The washing liquid generated by the second - stage plate - and - frame filtration is used for counter - current washing of the original chlorine - removed ash, fully dissolving most of the chloride ions in the original chlorine - removed ash, effectively increasing the chloride ion consumption in the washing liquid, reducing the make - up water volume of the system's clean water, and reducing the operating power consumption of the subsequent evaporation and salt - separation system.

[0019] In the above step (4), the separated water enters the subsequent water treatment system; the separated solid ash with a chloride ion content of < 3% enters the second - stage water - washing.

[0020] In the above step (5), the solid ash enters the second - stage water - washing tank for about 1 h of cleaning to ensure that the chloride ion content of the chlorine - removed ash separated in step (6) is < 1%.

[0021] In the above step (6), the separated water returns to step (2); the separated solid ash with a moisture content of < 30% and a chloride ion content of < 1% returns to the cement kiln for use as raw materials.

[0022] In the above step (7), the water separated in step (4) contains Cl - 、K + 、Na+ , Ca 2+ , Mg 2+ and suspended solids, add CO3 2- to remove Ca 2+ , Mg 2+ from the solution. CO3 2- uses Na2CO3 reagent; this reaction is carried out in a decalcification reaction tank. The water in the decalcification reaction tank, after being separated by a decalcification plate and frame, the solid substances enter the secondary water washing tank for further cleaning; the separated water enters a multi-media filtration or ceramic membrane system to remove suspended solids. If the water separated in step (4) directly enters the evaporation and salt separation system, it will cause scaling and blockage of this system. Therefore, Na2CO3 reagent is used for hardness removal, converting Ca 2+ , Mg 2+ into precipitates, and then discharging them through the decalcification plate and frame, controlling the hardness (calculated as Ca 2+ ) ≤ 100 mg / L; subsequently, the multi-media filtration or ceramic membrane system is used to reduce the suspended solids, controlling the suspended solids ≤ 10 mg / L, ensuring the stable operation of the evaporation and salt separation system and improving the quality of by-product salt.

[0023] In the above step (8), the steam required by the evaporation and salt separation system uses the steam generated by the cement kiln waste heat power generation system to heat up the purified brine, separating sodium chloride and potassium chloride. The condensed water generated by evaporation returns to the secondary water washing tank in step (5) for recycling. The heavy metal indexes of the crystallized salt after disposal meet the standard of "Washed Chloride of Pretreatment Products for Co-processing Fly Ash in Cement Kiln" T / CCAS - 010 - 2019, and are sold and comprehensively utilized as industrial salt. The sodium salt meets the index requirements of the national "Industrial Salt" GB / T5462 - 2015 second-class solar salt, and the separated potassium salt meets the standard of the national standard "Potassium Chloride" (GB6549 - 2011) Class 2 qualified products. The condensed water generated by evaporation is recycled, achieving zero discharge of wastewater.

[0024] One of the technical solutions in the above technical solutions has the following advantages or beneficial effects. Adopting the process of "secondary countercurrent water washing + water quality purification + evaporation", the dechlorinated ash is treated on-site at the cement kiln to obtain potassium chloride and sodium chloride products. The dechlorinated ash after water washing can be returned to the cement kiln as raw materials. It reduces the chloride ion content in cement clinker, saves the cost of cement raw materials, reduces the cost of outsourcing the disposal of dechlorinated ash, and can also realize the resource utilization of potassium chloride and sodium chloride. Description of the Drawings

[0025] Figure 1 is the schematic diagram of the method for resource utilization of washing dechlorinated ash from bypass air extraction of cement kiln provided in the embodiment of the present invention; Detailed Embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Embodiment 1

[0028] See Figure 1 , a method for resource utilization of chlorine-removing ash water washing from the bypass air discharge of a cement kiln, comprising the following steps:

[0029] 1) The cement kiln produces chlorine-removing ash;

[0030] 2) The chlorine-removing ash enters the premixing tank for premixing;

[0031] 3) The premixed slurry is pumped into the first-stage water washing tank for stirring and cleaning;

[0032] 4) The slurry in the first-stage water washing tank is pumped into the first-stage centrifugal equipment for solid-liquid separation;

[0033] 5) The solid ash separated in step (4) enters the second-stage water washing tank for stirring and cleaning;

[0034] 6) The slurry in the second-stage water washing tank is pumped into the second-stage plate and frame equipment for solid-liquid separation;

[0035] 7) The water separated in step (4) is treated in the demineralization reaction tank;

[0036] 8) The purified brine enters the evaporation system to separate sodium chloride and potassium chloride.

[0037] In the above step 1), when the cement kiln is operating and the chloride ion and alkali contents in the system reach the set values, the hot air in the smoke chamber part is extracted, so that the chloride ions and alkali metals are carried out of the kiln system with the hot air, and then after rapid cooling, cyclone and dust removal treatments, chlorine-removing ash is obtained.

[0038] In the above step 1), the chloride ion content in the chlorine-removing ash is 15-40%, the potassium oxide content is 10-25%, and the sodium oxide content is 0-5%; other components include calcium oxide, silicon dioxide, aluminum oxide, and iron oxide.

[0039] In the above step 2), after the chlorine-removing ash is metered and regulated, it first enters the premixing tank and is premixed with the water filtered by the second-stage plate and frame, and the water-to-ash ratio is controlled at 1:3.

[0040] In the above step 4), the separated water enters the subsequent water treatment system; the separated solid ash with a chloride ion content < 3% enters the second-stage water washing.

[0041] In the above step 5), the solid ash enters the secondary water washing tank and is washed for about 1 h.

[0042] In the above step 6), the separated water is returned to step (2); the separated solid ash, with a moisture content of < 30% and a chloride ion content of 1%, is returned to the cement kiln for use as a raw material.

[0043] In the above step 7), the water separated in step (4) contains Cl - , K + , Na + , Ca 2+ , Mg 2+ and suspended solids. CO3 2- is added to remove Ca 2+ , Mg 2+ from the solution. Na2CO3 reagent is used for CO3 2- ; this reaction is carried out in a decalcification reaction tank. The water in the decalcification reaction tank, after being separated by a decalcification plate and frame, the solid matter enters the secondary water washing tank for further washing; the separated water enters the water quality purification system to remove suspended solids.

[0044] In the above step 8), the steam required for evaporation utilizes the steam generated by the cement kiln system, and the evaporated and condensed water is returned to the secondary water washing tank in step (5) for recycling.

[0045] Beneficial effects:

[0046] (1) After the chlorine-removing ash is washed with water, the chloride ion content is about 1%, and it can be used as a raw material for cement clinker.

[0047] (2) The quality of the by-products sodium chloride and potassium chloride meets the requirements of the secondary index of industrial dry salt in "Industrial Salt" (GB / T 5462-2015) and the requirements of Class I qualified products in potassium chloride for industrial and agricultural use in "Potassium Chloride" (GB 6549-2011), respectively.

[0048] (3) The wastewater in the water washing process is all recycled after being treated and evaporated, and is not discharged.

[0049] (4) The system does not generate waste gas pollutants.

[0050] After adopting the above scheme, the process of "secondary countercurrent water washing + water quality purification + evaporation" is used to treat the chlorine-removing ash on-site in the cement kiln to obtain potassium chloride and sodium chloride products. The chlorine-removing ash after water washing can be returned to the cement kiln for use as a raw material. It reduces the cost of outsourcing the disposal of chlorine-removing ash and can also realize the resource utilization of potassium chloride and sodium chloride.

[0051] Example 2

[0052] A method for resource utilization of chlorine-removing ash from cement kiln bypass flue gas by water washing, comprising the following steps:

[0053] (1) When the cement kiln is operating and the chloride ion and alkali content in the system are relatively high, about 1050 °C hot air is extracted from the smoke chamber, and the chloride ions and alkali metals are carried out of the kiln system with the hot air, and then are quenched, cycloned, and dust-removed. The proportion of hot air is generally 3% of the air distribution in the smoke chamber. Taking a 5000 t / d scale cement kiln as an example, the amount of chlorine-removing ash collected per day is about 10 t. The chloride ion content in the chlorine-removing ash is about 15-40%, the potassium oxide content is about 10-25%, and the sodium oxide content is about 0-5%; the other main components are calcium oxide, silicon dioxide, aluminum oxide, iron oxide, etc.

[0054] (2) After the chlorine-removing ash is metered and regulated, it first enters the premixing tank and is premixed with the water filtered by the secondary plate and frame, and the water-to-ash ratio is controlled at about 1:3;

[0055] (3) The premixed slurry is pumped into the first-stage water washing tank for stirring and cleaning, and the cleaning time is about 1 h;

[0056] (4) The slurry in the first-stage water washing tank is pumped into the first-stage centrifugal equipment for solid-liquid separation. The separated water enters the subsequent water treatment system; the separated solid ash, with a chloride ion content < 3%, enters the second-stage water washing;

[0057] (5) The solid ash separated in step (4) enters the second-stage water washing tank for stirring and cleaning, and the cleaning time is about 1 h;

[0058] (6) The slurry in the second-stage water washing tank is pumped into the second-stage plate and frame equipment for solid-liquid separation. The separated water returns to step (2); the separated solid ash, with a moisture content < 30% and a chloride ion content of about 1%, returns to the cement kiln for use as a raw material.

[0059] (7) The water separated in step (4) mainly contains Cl - , K + , Na + , Ca 2+ , Mg 2+ , and suspended solids, etc. In order to ensure the stable operation of the backend evaporation system and improve the quality of salt, CO3 2- needs to be added to remove Ca 2+ , Mg 2+ in the solution. In the present invention, Na2CO3 reagent is mainly used. This reaction is carried out in a decalcification reaction tank. The water in the decalcification reaction tank, after being separated by a decalcification plate and frame, the solid matter enters the second-stage water washing tank for further cleaning. The separated water enters the water purification system to remove suspended solids.

[0060] (8) The purified brine enters the evaporation system to separate sodium chloride and potassium chloride products for external sales. The steam required for evaporation can utilize the steam generated by the cement kiln system, and the condensed water from evaporation returns to the secondary water wash tank in step (5) for recycling.

[0061] Beneficial effects:

[0062] (1) After the chlorine-removing ash is washed with water, the chloride ion content is about 1%, and it can be used as a raw material for cement clinker.

[0063] (2) The quality of the by-products sodium chloride and potassium chloride meets the requirements of the secondary index of industrial dry salt in "Industrial Salt" (GB / T 5462-2015) and the requirements of Class I qualified products for potassium chloride for industrial and agricultural use in "Potassium Chloride" (GB 6549-2011), respectively.

[0064] (3) The wastewater in the water washing process is treated, evaporated, and then all recycled without external discharge.

[0065] (4) No waste gas pollutants are generated in the system.

[0066] After adopting the above scheme, the process of "secondary countercurrent water washing + water quality purification + evaporation" is used to treat the chlorine-removing ash on-site in the cement kiln to obtain potassium chloride and sodium chloride products. The chlorine-removing ash after water washing can return to the cement kiln as a raw material. It reduces the chloride ion content in the cement clinker, saves the cost of cement raw materials, reduces the cost of outsourcing the disposal of chlorine-removing ash, and also realizes the resource utilization of potassium chloride and sodium chloride.

[0067] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention.

[0068] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "set", "connected", "fixed", "swiveling connection", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the internal communication of two elements or the interaction relationship between two elements. Unless otherwise clearly limited, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for resource utilization of chlorine-removing ash washed by bypass air extraction from a cement kiln, characterized in that, It includes the following steps: 1) Produce chlorine-removed ash in the cement kiln; 2) The chlorine-removed ash enters the premixing tank for premixing; 3) The premixed slurry is pumped into the first-stage water washing tank for stirring and cleaning; 4) The slurry in the first-stage water washing tank is pumped into the first-stage centrifugal equipment for solid-liquid separation; 5) The solid ash separated in step (4) enters the second-stage water washing tank for stirring and cleaning; 6) The slurry in the second-stage water washing tank is pumped into the second-stage plate and frame equipment for solid-liquid separation; 7) The water separated in step (4) is treated in the demineralization reaction tank; 8) The purified brine enters the evaporation system to separate sodium chloride and potassium chloride.

2. The method for resource utilization of chlorine-removing ash water washing in the bypass air discharge of a cement kiln according to claim 1, characterized in that In the above step 1), when the contents of chloride ions and alkalis in the system reach the set values during the operation of the cement kiln, the hot air in the smoke chamber is extracted, so that the chloride ions and alkali metals are carried out of the kiln system with the hot air, and then through rapid cooling, cyclone and dust removal treatments to obtain the chlorine-removed ash.

3. The method for resource utilization of chlorine-removing ash washing by bypass air extraction from a cement kiln according to claim 2, wherein, In the above step 1), the chlorine content in the chlorine-removed ash is 15-40%, the potassium oxide content is 10-25%, and the sodium oxide content is 0-5%; other components include calcium oxide, silicon dioxide, aluminum oxide and iron oxide.

4. The method for resource utilization of chlorine-removing ash water washing in the bypass air release of a cement kiln according to claim 3, characterized in that, In the above step 2), after the chlorine-removed ash is measured and regulated, it first enters the premixing tank and is premixed with the water filtered by the second-stage plate and frame to control the water-to-ash ratio at 1:

3.

5. The method for resource utilization of chlorine-removing ash water washing in the bypass air release of a cement kiln according to claim 4, wherein, In the above step 4), the separated water enters the subsequent water treatment system; the separated solid ash with a chlorine content of <3% enters the second-stage water washing.

6. The method for resource utilization of chlorine-removing ash water washing in the bypass air release of a cement kiln as described in claim 5, wherein, In the above step 5), the solid ash enters the second-stage water washing tank and is washed for about 1 h.

7. The method for resource utilization of chlorine-removing ash washing in the bypass air release of a cement kiln according to claim 6, characterized in that In the above step 6), the separated water returns to step (2); the separated solid ash with a moisture content of <30% and a chlorine content of 1% returns to the cement kiln for use as a raw material.

8. The method for resource utilization of chlorine-removing ash water washing in the bypass air discharge of a cement kiln according to claim 7, characterized in that In the above step 7), the water separated in step (4) contains Cl - , K + , Na + , Ca 2+ , Mg 2+ and suspended solids. CO3 2- is added to remove Ca 2+ , Mg 2+ in the solution. Na2CO3 reagent is used for CO3 2- . This reaction is carried out in a decalcification reaction tank. The water in the decalcification reaction tank, after being separated by a decalcification plate and frame, the solid substances enter the secondary water washing tank for further cleaning; the separated water enters the water quality purification system to remove suspended solids.

9. The method for resource utilization of chlorine-removing ash washing in the bypass air discharge of a cement kiln according to claim 8, wherein In the above step 8), the steam required for evaporation uses the steam generated by the cement kiln system, and the evaporated and condensed water returns to the second-stage water washing tank in step (5) for recycling.

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