Method and system for disposal of wastewater from washing of fly ash using waste heat from cement kiln

Abstract

The application discloses a method and system for disposing water washing fly ash wastewater by using cement kiln waste heat, and first carries out a system starting stage step to prepare steam and saturated critical state concentrated brine, and then enters a system running stage step after the concentrated brine meets the requirements; the system starting stage step comprises waste heat utilization and preparation of saturated critical state concentrated brine; the system running stage step comprises waste heat utilization, washing ash wastewater preheating and washing ash wastewater spray separation. The system comprises a cement kiln waste heat recovery unit for recovering cement kiln tail waste heat flue gas heat to change the water washing fly ash wastewater into a superheated state, a washing ash wastewater spray evaporation separation unit for carrying out spray evaporation on the superheated washing ash wastewater and separation of steam, concentrated brine and crystallized salt, and a washing ash wastewater preheating unit for realizing washing ash wastewater recovery heat pump condensing heat and steam condensation heat. The application greatly reduces washing ash wastewater disposal energy consumption by recycling cement kiln waste heat and using waste heat.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and energy conservation and environmental protection technology, and in particular relates to a method and system for treating water-washed fly ash wastewater using waste heat from cement kilns. Background Technology

[0002] Co-processing of municipal solid waste fly ash in cement kilns has become a novel technology for fly ash disposal. This technology not only enables large-scale disposal of fly ash but also fully utilizes it as a resource. However, fly ash needs to undergo dechlorination treatment before entering the cement kiln; otherwise, chloride ions in the fly ash will not only affect the normal production of the cement kiln but also the quality of cement clinker, thus limiting the scale of fly ash disposal.

[0003] Fly ash washing technology is the main method for removing chloride ions from fly ash. This method transfers soluble substances (potassium, sodium, and chloride ions) from the fly ash to the washing wastewater. Therefore, the washing wastewater has a high salt content and is classified as high-salt wastewater. If this wastewater is to be reused in the washing process, it must be desalinated. Currently, the main treatment process for fly ash washing wastewater uses MVR technology, which stands for mechanical vapor recompression. MVR is an energy-saving technology that reuses the energy of the secondary steam it generates, thereby reducing the demand for external energy. However, this technology uses electricity to drive the compressor, and the motor has a very high power output, causing the electricity consumption of the MVR section to account for more than half of the total energy consumption of the entire washing process.

[0004] In addition, the amount of flue gas generated at the tail end of cement kilns is very large, but the quality of this waste heat is low and it is difficult to use directly. At present, almost all cement plants directly discharge this part of the exhaust gas.

[0005] In summary, the problems with existing technologies are:

[0006] (1) The desalination technology for fly ash wastewater from water washing adopts the MVR method. This technology is driven by electricity, which consumes a lot of electricity, resulting in high energy consumption of the entire water washing system.

[0007] (2) The waste heat flue gas from cement kilns cannot be directly applied to the treatment of fly ash washing wastewater. Because fly ash washing wastewater is high-salt wastewater with a saturated vapor pressure higher than atmospheric pressure, the atmospheric boiling point of fly ash washing wastewater is greater than 100℃, around 105-110℃, which is similar to the temperature of cement kiln flue gas, so it is difficult to apply it directly. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method and system for treating water-washed fly ash wastewater using waste heat from cement kilns. This method achieves efficient utilization of the heat from the waste gas at the kiln tail of the cement kiln, and significantly reduces the energy consumption for treating water-washed fly ash wastewater.

[0009] This invention is implemented as follows: a method for treating fly ash wastewater using waste heat from a cement kiln, comprising the following steps:

[0010] The system startup phase is carried out first, producing steam and concentrated brine at the critical saturation state. Once the concentrated brine meets the requirements, the system operation phase is then initiated.

[0011] The system startup process consists of the following steps:

[0012] Waste heat utilization: The waste heat flue gas from the tail of the cement kiln is introduced into the second type of absorption heat pump mechanism and sent to the evaporator and generator in the heat pump mechanism respectively; the heat pump mechanism is used to divide this part of the heat source into two parts of heat energy, the heat pump absorber in the heat pump mechanism generates high heat energy, and the heat pump condenser generates low heat energy.

[0013] To produce concentrated brine at the saturated critical state: Wastewater from ash washing is preheated in a heat pump condenser, then fed into the first medium channel of a heat exchanger. It is then pumped to the heat pump absorber via a booster pump for heat exchange, becoming superheated wastewater. This superheated wastewater is then sent to a spray evaporation separation mechanism, where it is converted into steam and concentrated brine. The steam enters the second medium channel of the heat exchanger. The concentrated brine is pumped into the heat pump absorber for heat exchange, then into the spray evaporation separation mechanism for continuous heating and evaporation until it reaches the saturated critical state, at which point it enters the spray evaporation separation mechanism. During system startup, the heat pump condenser and heat exchanger are cooled by cooling water.

[0014] The system operation phase steps are as follows:

[0015] Waste heat utilization: The waste heat flue gas from the tail of the cement kiln is introduced into the second type of absorption heat pump mechanism and sent to the generator in the heat pump mechanism; the heat pump mechanism is used to divide this part of the heat source into two parts of heat energy, the heat pump absorber generates high heat energy, and the heat pump condenser generates low heat energy.

[0016] Preheating of ash washing wastewater: The ash washing wastewater is sent to the heat pump condenser for preheating. After preheating, it is sent to the first medium channel of the heat exchanger to exchange heat with the steam sent to the second medium channel of the heat exchanger. After heat exchange, it is mixed with circulating concentrated brine. Then, the mixture is sent to the heat pump absorber by a booster pump to produce superheated ash washing wastewater.

[0017] Wastewater spray separation for ash washing: Superheated wastewater from ash washing is sent to a spray evaporation separation unit. After spray depressurization and atomization, some of the superheated water evaporates rapidly into steam. At this time, the spray evaporation separation unit contains three phases of materials: steam, concentrated brine, and crystalline salt. The steam is divided into two parts: one part enters the second medium channel of the heat exchanger, and the other part enters the evaporator. After heat exchange in the heat exchanger and evaporator, the steam is converted into condensate for reuse. The concentrated brine, as a circulating carrier, enters the pipeline between the heat exchanger and the booster pump, and mixes again with the wastewater from ash washing after heat exchange. The crystalline salt is separated and reused.

[0018] Preferably, the waste heat flue gas at the kiln tail is the exhaust gas after the cement kiln tail exhaust fan, with a temperature of 100-110℃; the flue gas after waste heat utilization is discharged through the flue gas emission port.

[0019] Preferably, the formula for calculating the volume of waste heat flue gas (g) at the kiln tail of the cement kiln is as follows:

[0020] g=δ·(q1·(1-c1)·(t1-t2)·c 水 +q1·c1·(t1-t3)·c 盐 ) / ((t4-t5)·c 烟气 )

[0021] In the formula: g is the waste heat flue gas volume at the tail of the cement kiln, in Nm³. 3 / h;

[0022] δ represents the thermal efficiency, taken as 0.7-0.8;

[0023] q1 is the initial flow rate of the ash washing wastewater, in kg / h;

[0024] c1 is the salt concentration of the initial ash washing wastewater, in %;

[0025] t1, t2, and t3 are the initial ash washing wastewater temperature, average condensate temperature, and crystallization salt temperature, respectively, all in °C.

[0026] t4 and t5 are the inlet temperature and outlet temperature of the waste heat flue gas of the heat pump mechanism, respectively, both in °C.

[0027] c 水 c 盐 c 烟气 These are the specific heat of water, the specific heat of crystalline salt, and the specific heat of waste heat flue gas, respectively, with units of kJ / kg·℃, kJ / kg·℃, and kJ / Nm³. 3 ·℃.

[0028] Preferably, the temperature of the higher-grade thermal energy is 150-160℃, and the temperature of the lower-grade thermal energy is 50-60℃.

[0029] Preferably, the gauge pressure of the superheated ash washing wastewater is 0.26-0.38 MPa and the temperature is 140-150℃.

[0030] Preferably, the steam gauge pressure inside the spray evaporation separation mechanism is -0.02 MPa.

[0031] Preferably, in the system operation phase steps, the relationship between the initial ash washing wastewater flow rate and the circulating concentrated brine flow rate satisfies:

[0032] q1 = q2·τ / (1-c1)

[0033] In the formula: q1 is the initial flow rate of the ash washing wastewater, in kg / h;

[0034] q2 is the flow rate of the circulating concentrated brine, in kg / h;

[0035] τ is the steam coefficient, taken as 0.09-0.11;

[0036] c1 represents the salt concentration of the initial ash washing wastewater, expressed as a percentage.

[0037] Preferably, in the system operation phase steps, the ash washing wastewater refers to pretreated wastewater with a water hardness of <50mg / L, turbidity of <5NTU, and salt content of 6wt%-15wt%.

[0038] Preferably, in the system operation phase, the ratio of steam entering the heat exchanger to steam entering the evaporator is 1:11-14.

[0039] A system for treating fly ash wastewater using waste heat from a cement kiln includes a cement kiln waste heat recovery unit, a fly ash wastewater spray evaporation separation unit, and a fly ash wastewater preheating unit.

[0040] The cement kiln waste heat recovery unit is used to recover the heat of the waste flue gas at the kiln tail of the cement kiln using a heat pump to turn the water-washed fly ash wastewater into a superheated state. It includes a second type of absorption heat pump mechanism and a booster pump. The second type of absorption heat pump mechanism includes an evaporator, a generator, a heat pump absorber, and a heat pump condenser.

[0041] The ash washing wastewater spray evaporation separation unit is used to spray evaporate superheated ash washing wastewater and separate steam, concentrated brine, and crystalline salt, including a spray evaporation separation mechanism;

[0042] The ash washing wastewater preheating unit is used to recover heat from heat pump condensation and steam condensation in ash washing wastewater, and includes a heat exchanger.

[0043] The evaporator is provided with a flue gas inlet, a flue gas outlet, a steam inlet, and a condensate outlet. The generator is provided with a flue gas inlet and a flue gas outlet. The flue gas inlet of the evaporator and the flue gas inlet of the generator are both connected to the waste heat flue gas pipeline at the tail of the cement kiln. The flue gas outlet of the evaporator and the flue gas outlet of the generator are both connected to the flue gas emission outlet.

[0044] The heat pump condenser is provided with a ash washing wastewater inlet, and the ash washing wastewater outlet of the heat pump condenser is connected to the inlet of the first medium channel of the heat exchanger. The outlet of the first medium channel of the heat exchanger is connected to the inlet of the booster pump. The outlet of the booster pump is connected to the inlet of the heat pump absorber. The outlet of the heat pump absorber is connected to the inlet of the spray evaporation separation mechanism. The steam outlet of the spray evaporation separation mechanism is connected to the inlet of the second medium channel of the heat exchanger and the steam inlet of the evaporator. The concentrated brine outlet of the spray evaporation separation mechanism is connected to the pipeline between the outlet of the first medium channel of the heat exchanger and the inlet of the booster pump. The spray evaporation separation mechanism is also provided with a crystallized salt outlet.

[0045] The outlet of the second medium channel of the heat exchanger and the outlet of the condensate of the evaporator are both connected to the fly ash washing system.

[0046] Preferably, the second type of absorption heat pump mechanism is a lithium bromide second type heating absorption heat pump mechanism.

[0047] Preferably, the spray evaporation separation mechanism is an atomizing three-phase separator.

[0048] The advantages and positive effects of this invention are:

[0049] This invention employs a second-type absorption heat pump technology to separate the waste heat from the kiln tail of a cement kiln into two parts: high-grade heat energy and low-grade heat energy, thus achieving efficient utilization of the heat from the waste heat from the kiln tail. Internally, the system utilizes multi-stage preheating, concentration, and mixing of the wastewater from the washing fly ash, followed by a booster pump to ensure the wastewater is in a superheated state. Spray depressurization evaporation achieves the wastewater treatment process, and the steam heat pump reuse effectively reduces the energy consumption for treating high-salt wastewater. Attached image description:

[0050] Figure 1 This is a flowchart of a system for treating fly ash wastewater using waste heat from a cement kiln, provided in an embodiment of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0052] Example 1

[0053] This embodiment provides a method for treating wastewater from cement kiln fly ash washing using waste heat, comprising the following steps:

[0054] The system startup phase begins with the following steps:

[0055] Waste heat utilization: The waste heat flue gas from the kiln tail of a cement plant at 110℃ is introduced into a second-type absorption heat pump mechanism and sent to the evaporator and generator in the heat pump mechanism respectively; the heat pump mechanism is used to divide this part of the heat source into two parts of heat energy, the heat pump absorber in the heat pump mechanism generates high heat energy (160℃) and the heat pump condenser generates low heat energy (50℃).

[0056] Preparation of concentrated brine at saturation critical state: Washing wastewater at 15℃ (6% salt content) is preheated in the heat pump condenser. After preheating, it enters the first medium channel of the heat exchanger and is then pumped to the heat pump absorber for heat exchange. After heat exchange, it becomes superheated washing wastewater (at 0.38 MPa and 150℃). This superheated wastewater is then sent to the spray evaporation separation mechanism, where it is converted into steam and concentrated brine. The steam enters the second medium channel of the heat exchanger. The concentrated brine continues to be pumped to the heat pump absorber for heat exchange, and then enters the spray evaporation separation mechanism for cyclic heating and evaporation until the concentrated brine reaches saturation critical state, at which point it enters the spray evaporation separation mechanism. During system startup, the heat pump condenser and heat exchanger are cooled by cooling water.

[0057] After the concentrated brine meets the requirements, the system operation phase begins, and the system operation phase steps are as follows:

[0058] Waste heat utilization: The waste heat flue gas from the kiln tail of a cement plant at 110℃ is introduced into a second-type absorption heat pump mechanism and sent to the generator in the heat pump mechanism; the heat pump mechanism is used to divide this part of the heat source into two parts of heat energy, the heat pump absorber in the heat pump mechanism generates high-grade heat energy (160℃) and the heat pump condenser generates low-grade heat energy (50℃).

[0059] Preheating of ash washing wastewater: 15℃ ash washing wastewater (6% salt content) is sent to the heat pump condenser for preheating. After preheating, it is sent to the first medium channel of the heat exchanger to exchange heat with the steam sent to the second medium channel of the heat exchanger. After heat exchange, it is mixed with the circulating concentrated brine from the spray evaporation separation mechanism. The mixing ratio is circulating concentrated brine: initial ash washing wastewater = 8.5:1. Then, the mixture is sent to the heat pump absorber for heat exchange through a booster pump. After heat exchange, it becomes superheated ash washing wastewater (state is 0.38Mpa, 150℃).

[0060] Ash washing wastewater spray separation: Superheated ash washing wastewater is sent to a spray evaporation separation unit. In the atomizing three-phase separator, the following process is achieved: Part of the superheated water is rapidly converted into steam, which is then divided into two parts through the gas phase channel. One part enters the second medium channel of the heat exchanger, where it exchanges heat with the ash washing wastewater and becomes condensate for reuse. The other part enters the evaporator, condenses, and is then reused. The flow rates of both parts are (unit: m³). 3 The ratio of / h) is 1:14; the unevaporated ash washing wastewater is converted into circulating concentrated brine and mixed with the ash washing wastewater again, enters the heat pump absorber for heat exchange, and then enters the spray evaporation separation mechanism for circulating heating and evaporation; the solid phase crystalline salt is separated out for resource recycling.

[0061] Calculations show that the method of this invention for treating fly ash wastewater reduces energy consumption by approximately 30% compared to similar MVR methods.

[0062] Example 2

[0063] This embodiment provides a method for treating wastewater from cement kiln fly ash washing using waste heat, comprising the following steps:

[0064] The system startup phase begins with the following steps:

[0065] Waste heat utilization: The waste heat flue gas from the kiln tail of a cement plant at 105℃ is introduced into a second-type absorption heat pump mechanism and sent to the evaporator and generator in the heat pump mechanism respectively; the heat pump mechanism is used to divide this part of the heat source into two parts of heat energy, the heat pump absorber in the heat pump mechanism generates high heat energy (150℃) and the heat pump condenser generates low heat energy (60℃).

[0066] Preparation of concentrated brine at saturation critical state: Washing wastewater at 20℃ (15% salt content) is preheated in the heat pump condenser. After preheating, it enters the first medium channel of the heat exchanger and is then pumped to the heat pump absorber for heat exchange. After heat exchange, it becomes superheated washing wastewater (state: 0.26 MPa, 140℃). This superheated wastewater is then sent to the spray evaporation separation mechanism, where it is converted into steam and concentrated brine. The steam enters the second medium channel of the heat exchanger. The concentrated brine continues to be pumped to the heat pump absorber for heat exchange, and then enters the spray evaporation separation mechanism for cyclic heating and evaporation until the concentrated brine reaches saturation critical state, at which point it enters the spray evaporation separation mechanism. During system startup, the heat pump condenser and heat exchanger are cooled by cooling water.

[0067] After the concentrated brine meets the requirements, the system operation phase begins, and the system operation phase steps are as follows:

[0068] Waste heat utilization: The waste heat flue gas from the kiln tail of a cement plant at 105℃ is introduced into a second-type absorption heat pump mechanism and sent to the generator in the heat pump mechanism. The heat pump mechanism divides this part of the heat source into two parts of heat energy: the heat pump absorber in the heat pump mechanism generates high-grade heat energy (150℃) and the heat pump condenser generates low-grade heat energy (60℃).

[0069] Preheating of ash washing wastewater: 20℃ ash washing wastewater (salt content 15%) is sent to the heat pump condenser for preheating. After preheating, it is sent to the first medium channel of the heat exchanger to exchange heat with the steam sent to the second medium channel of the heat exchanger. After heat exchange, it is mixed with the circulating concentrated brine from the spray evaporation separation mechanism. The mixing ratio is circulating concentrated brine: initial ash washing wastewater = 9.4:1. Then, the mixture is sent to the heat pump absorber for heat exchange through a booster pump. After heat exchange, it becomes superheated ash washing wastewater (state 0.26Mpa, 140℃).

[0070] Ash washing wastewater spray separation: Superheated ash washing wastewater is sent to a spray evaporation separation unit. In the atomizing three-phase separator, the following process is achieved: Part of the superheated water is rapidly converted into steam, which is then divided into two parts through the gas phase channel. One part enters the second medium channel of the heat exchanger, where it exchanges heat with the ash washing wastewater and becomes condensate for reuse. The other part enters the evaporator, condenses, and is then reused. The flow rates of both parts are (unit: m³). 3 The ratio of / h) is 1:11; the unevaporated ash washing wastewater is converted into circulating concentrated brine and mixed with the ash washing wastewater again, enters the heat pump absorber for heat exchange, and then enters the spray evaporation separation mechanism for circulating heating and evaporation; the solid phase crystalline salt is separated out for resource recycling.

[0071] Calculations show that the method of this invention for treating fly ash wastewater reduces energy consumption by approximately 20% compared to similar MVR methods.

[0072] The above description provides a detailed account of this embodiment, but it is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for treating wastewater from cement kiln washing fly ash using waste heat, characterized in that: Includes the following steps: The system startup phase is carried out first, producing steam and concentrated brine at the critical saturation state. Once the concentrated brine meets the requirements, the system operation phase is then initiated. The system startup process consists of the following steps: Waste heat utilization: The waste heat flue gas from the tail of the cement kiln is introduced into the second type of absorption heat pump mechanism and sent to the evaporator and generator in the heat pump mechanism respectively; the heat pump absorber in the heat pump mechanism generates high-grade heat energy, and the heat pump condenser generates low-grade heat energy. Preparation of concentrated brine at saturation critical state: Wastewater from ash washing is preheated in a heat pump condenser, then fed into the first medium channel of a heat exchanger, and subsequently pumped into a heat pump absorber for heat exchange. After heat exchange, it becomes superheated wastewater from ash washing. This superheated wastewater is then fed into a spray evaporation separation mechanism, where it is converted into steam and concentrated brine. The steam enters the second medium channel of the heat exchanger. The concentrated brine is pumped into the heat pump absorber for heat exchange, and then into the spray evaporation separation mechanism for cyclic heating and evaporation until it reaches saturation critical state, at which point it enters the spray evaporation separation mechanism. During system startup, the heat pump condenser and heat exchanger are cooled by cooling water. The system operation phase steps are as follows: Waste heat utilization: The waste heat flue gas from the tail of the cement kiln is introduced into the second type of absorption heat pump mechanism and sent to the generator in the heat pump mechanism; the heat pump absorber generates high-grade heat energy, and the heat pump condenser generates low-grade heat energy. Preheating of ash washing wastewater: The ash washing wastewater is sent to the heat pump condenser for preheating. After preheating, it is sent to the first medium channel of the heat exchanger to exchange heat with the steam sent to the second medium channel of the heat exchanger. After heat exchange, it is mixed with circulating concentrated brine. Then, the mixture is sent to the heat pump absorber by a booster pump to obtain superheated ash washing wastewater. Ash washing wastewater spray separation: Superheated ash washing wastewater is sent to the spray evaporation separation unit. After spray depressurization and atomization, three phases of materials are present in the spray evaporation separation unit: steam, concentrated brine, and crystalline salt. The steam is divided into two parts: one part enters the second medium channel of the heat exchanger, and the other part enters the evaporator. After heat exchange in the heat exchanger and evaporator, the steam is converted into condensate for reuse. The concentrated brine enters the pipeline between the heat exchanger and the booster pump and mixes with the ash washing wastewater after heat exchange. The crystalline salt is separated and reused.

2. The method for treating fly ash wastewater from cement kiln waste heat according to claim 1, characterized in that, The waste heat flue gas at the kiln tail is the exhaust gas after the cement kiln tail exhaust fan, with a temperature of 100-110℃; the flue gas after waste heat utilization is discharged through the flue gas emission port.

3. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, The formula for calculating the waste heat flue gas volume (g) at the kiln tail of the cement kiln is as follows: In the formula: g is the waste heat flue gas volume at the tail of the cement kiln, in Nm³. 3 / h; For optimal heat utilization efficiency, a value of 0.7-0.8 is used. The initial flow rate of the ash washing wastewater is expressed in kg / h. The salt concentration of the initial ash washing wastewater is expressed in % (%). These are the initial ash washing wastewater temperature, average condensate temperature, and crystallization salt temperature, all in °C. These are the inlet temperature and outlet temperature of the waste heat flue gas of the heat pump mechanism, respectively, both in °C. These are the specific heat of water, the specific heat of crystalline salt, and the specific heat of waste heat flue gas, respectively, with units of kJ / kg·℃, kJ / kg·℃, and kJ / Nm³. 3 ·℃.

4. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, The temperature of the higher-grade heat energy is 150-160℃, and the temperature of the lower-grade heat energy is 50-60℃.

5. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, The gauge pressure of the superheated ash washing wastewater is 0.26-0.38 MPa, and the temperature is 140-150℃.

6. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, The steam gauge pressure inside the spray evaporation separation mechanism is -0.02 MPa.

7. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, During the system operation phase, the relationship between the initial ash washing wastewater flow rate and the circulating concentrated brine flow rate satisfies: In the formula: q1 is the initial flow rate of the ash washing wastewater, in kg / h; q2 is the flow rate of the circulating concentrated brine, in kg / h; The steam coefficient is taken as 0.09-0.11; The initial salt concentration of the ash washing wastewater is expressed in units of %.

8. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, In the system operation phase steps, the ash washing wastewater refers to the pretreated wastewater with a water hardness of <50mg / L, turbidity of <5NTU, and salt content of 6wt%-15wt%.

9. The method for treating wastewater from cement kiln washing fly ash using waste heat according to claim 1, characterized in that, During the system operation phase, the ratio of steam entering the heat exchanger to steam entering the evaporator is 1:11-14.

10. A system for treating wastewater from cement kiln washing fly ash using waste heat, characterized in that, The system is used to implement the method according to any one of claims 1-9, the system comprising a cement kiln waste heat recovery unit, a ash washing wastewater spray evaporation separation unit, and an ash washing wastewater preheating unit; The cement kiln waste heat recovery unit is used to recover the heat of the waste flue gas at the kiln tail of the cement kiln using a heat pump to turn the water-washed fly ash wastewater into a superheated state. It includes a second type of absorption heat pump mechanism and a booster pump. The second type of absorption heat pump mechanism includes an evaporator, a generator, a heat pump absorber, and a heat pump condenser. The ash washing wastewater spray evaporation separation unit is used to spray evaporate superheated ash washing wastewater and separate steam, concentrated brine, and crystalline salt, including a spray evaporation separation mechanism; The ash washing wastewater preheating unit is used to recover heat from heat pump condensation and steam condensation in ash washing wastewater, and includes a heat exchanger. The evaporator is provided with a flue gas inlet, a flue gas outlet, a steam inlet, and a condensate outlet. The generator is provided with a flue gas inlet and a flue gas outlet. The flue gas inlet of the evaporator and the flue gas inlet of the generator are both connected to the waste heat flue gas pipeline at the tail of the cement kiln. The flue gas outlet of the evaporator and the flue gas outlet of the generator are both connected to the flue gas emission outlet. The heat pump condenser is provided with a ash washing wastewater inlet. The ash washing wastewater outlet of the heat pump condenser is connected to the inlet of the first medium channel of the heat exchanger. The outlet of the first medium channel of the heat exchanger is connected to the inlet of the booster pump. The outlet of the booster pump is connected to the inlet of the heat pump absorber. The outlet of the heat pump absorber is connected to the inlet of the spray evaporation separation mechanism. The steam outlet of the spray evaporation separation mechanism is connected to the inlet of the second medium channel of the heat exchanger and the steam inlet of the evaporator. The concentrated brine outlet of the spray evaporation separation mechanism is connected to the pipeline between the outlet of the first medium channel of the heat exchanger and the inlet of the booster pump. The spray evaporation separation mechanism is also provided with a crystallized salt outlet. The outlet of the second medium channel of the heat exchanger and the outlet of the condensate of the evaporator are both connected to the fly ash washing system.

11. The system for treating wastewater from cement kiln washing fly ash using waste heat according to claim 10, characterized in that, The second type of absorption heat pump mechanism is a lithium bromide second type heating absorption heat pump mechanism.

12. The system for treating wastewater from cement kiln washing fly ash using waste heat according to claim 10, characterized in that, The spray evaporation separation mechanism is an atomizing three-phase separator.

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