阅读说明：本技术 一种高含盐有机废水处置方法 (High-salt-content organic wastewater treatment method ) 是由 周永贤 张长富 张永良 陈纪赛 于 2021-09-13 设计创作，主要内容包括：本发明涉及一种高含盐有机废水处置方法,该方法包括低温干燥、有机物脱附、高温除盐、二次焚烧、余热回收和烟气净化等步骤,高含盐有机废水先经过低温干燥减量化后再对有机物进行脱附,经高温除盐实现固体盐颗粒与烟气分离,避免熔融态盐在余热回收装置上粘结,以确保余热回收装置正常运行,又由于采用低温干燥和余热回收的方式,提高了能量利用率。(The invention relates to a method for treating high-salt organic wastewater, which comprises the steps of low-temperature drying, organic matter desorption, high-temperature desalting, secondary incineration, waste heat recovery, flue gas purification and the like.)

1. The method for treating the high-salt-content organic wastewater is characterized by comprising the following steps of:

s1, low-temperature drying, namely, low-temperature drying is carried out on the high-salt organic wastewater until the water content of the material is 5% -10%;

s2, organic matter desorption, namely, introducing high-temperature flue gas into the solid material dried in the step S1 for heating, removing the organic matter and water in the solid material after gasification to form high-temperature flue gas containing salt, and leaving the solid material which is solid salt for recovery;

s3, high-temperature desalting, namely conveying the salt-containing high-temperature flue gas generated in the step S2 to a high-temperature desalter, and filtering to remove the particle salt in the flue gas to obtain recyclable particle salt;

s4, secondary incineration, namely mixing the flue gas subjected to high-temperature desalting filtration in the step S3 with the dried tail gas containing organic matters and water vapor generated in the step S1 through low-temperature drying, and then heating and incinerating the mixture to oxidize and decompose the organic matters in the mixed gas to obtain high-temperature flue gas;

s5, waste heat recovery, namely conveying the high-temperature flue gas obtained after secondary incineration in the step S4 to an air heat exchanger for heat exchange so as to recover the heat of the high-temperature flue gas;

and S6, flue gas purification, namely deacidifying and denitrating the flue gas subjected to the waste heat recovery in the step S5, and discharging the treated flue gas from a chimney.

2. The method for disposing the organic wastewater with high salt content according to claim 1, characterized in that: in the step S1, the organic wastewater with high salt content is dried at low temperature through a roller scraper dryer, the heat source of the roller scraper dryer comes from flue gas generated by fuel combustion, the fuel is preheated and supports combustion by adopting the heat recovered from the waste heat of the step S5 during combustion, the heat conducting medium of the roller scraper dryer adopts heat conducting oil or low-pressure steam of 0.5-0.8 MPa, and the drying temperature is 100-200 ℃.

3. The method for disposing the organic wastewater with high salt content according to claim 2, characterized in that: in the step S2, organic matter desorption adopts a spiral indirect heating or direct heating mode, the temperature of introduced high-temperature flue gas is 500-700 ℃, the high-temperature flue gas is from fuel combustion, and the fuel combustion adopts the heat recovered from the waste heat of the step S5 to preheat and support combustion.

4. The method for disposing the organic wastewater with high salt content according to claim 3, characterized in that: in the step S3, an acid and alkali corrosion resistant ceramic fiber filter pipe is arranged in the high-temperature desalter, and a group of filter holes with the aperture of 1-10 microns are formed in the filter pipe.

5. The method for disposing the organic wastewater with high salt content according to claim 4, characterized in that: in the step S4, the flue gas obtained after high-temperature desalination and the dry tail gas discharged after low-temperature drying in the step S1 are mixed together, the mixed flue gas is heated and incinerated in a combustion chamber, the heating and incinerating temperature is 1100-1150 ℃, and the retention time of the flue gas in the combustion chamber is 2S.

6. The method for disposing the organic wastewater with high salt content according to claim 5, characterized in that: in the step S5, the high-temperature flue gas exchanges heat with air in the air heat exchanger to preheat the air, the temperature of the flue gas after heat exchange is reduced to 180-200 ℃, and the heat of the preheated air is used for supporting combustion during fuel combustion.

7. The method for disposing the organic wastewater with high salt content according to claim 6, characterized in that: in the step S6, the flue gas deacidification adopts a flue gas purification deacidification agent, and the flue gas purification deacidification agent is sodium bicarbonate powder ground to 500 meshes.

Technical Field

The invention belongs to the technical field of salt-containing wastewater treatment, and particularly relates to a treatment method of high-salt-content organic wastewater.

Background

The high-salt organic wastewater refers to wastewater containing organic matters and Total Dissolved Solids (TDS) with the mass fraction not less than 3.5%, while the high-salt wastewater containing complex organic matters widely exists in the industries of chemical industry, petrifaction, pesticide and the like, the conventional distillation crystallization treatment cannot meet the environmental protection requirement, and organic oxygen matters are generally subjected to oxidative decomposition by adopting a high-temperature incineration decomposition method. When current high temperature incineration equipment handles high content organic waste water, because the fusing point that incineration temperature is greater than salt can lead to a large amount of evaporation gasification of salt, contain salt fly ash and bond easily at the equipment surface in the cooling process and cause the jam to also can produce high temperature corrosion, and then lead to the system operation unstable, finally lead to the waste heat can't obtain recycle.

The Chinese patent application with the publication number of CN112499875A discloses a desalting system and a desalting method for salt-containing organic wastewater, which utilize the principle of combining the action of circulating flash evaporation and alcohol precipitation and adopt a two-step method of gas-liquid separation and solid-liquid separation to realize the thorough separation of the salt and the organic wastewater and effectively solve the problem of easy blockage of the system; chinese patent publication No. CN111517549A discloses a process for treating organic wastewater containing salt, which comprises pretreating wastewater by adjusting PH of the wastewater, concentrating the wastewater by a nanofiltration membrane concentration system, concentrating the concentrated solution by drying equipment to obtain massive, flaky or powdery solid, and discharging the solid. The patent CN112499875A adopts a centrifugal machine for separation, the separation mode is not thorough, the separated salt necessarily contains water and organic matters, and the salt and flash gas after flash evaporation at a flash evaporation temperature not higher than the flash evaporation temperature both contain organic waste, namely, the salt obtained in the patent also contains residual moisture and organic matters, and the organic matters in the separated products (such as salt and flash gas) are not treated. Patent CN111517549A adopts membrane filtration to filter organic matter and salt together, has the same problem that the salt after filtration contains the organic matter, handles thoroughly and can not directly retrieve, and the membrane needs regeneration and change after long-time use, and the cost is higher.

Disclosure of Invention

The invention aims to solve the technical problems of fusion blockage, high-temperature corrosion and incapability of recycling waste heat caused by high-temperature incineration of wastewater in the prior art, and provides a method for treating high-salt-content organic wastewater.

In order to solve the technical problem, the invention provides a method for treating high-salt organic wastewater, which comprises the following steps:

s1, low-temperature drying, namely, low-temperature drying is carried out on the high-salt-content organic wastewater until the water content of the material is 5% -10%, so that a solid material is obtained;

s2, organic matter desorption, namely, introducing high-temperature flue gas into the solid material dried in the step S1 for heating, removing the organic matter and water in the solid material after gasification to form high-temperature flue gas containing salt, and leaving the solid material which is solid salt for recovery;

s3, high-temperature desalting, namely conveying the salt-containing high-temperature flue gas generated in the step S2 to a high-temperature desalter, and filtering to remove the particle salt in the flue gas to obtain recyclable particle salt and flue gas;

s4, secondary incineration, namely mixing the flue gas subjected to high-temperature desalting filtration in the step S3 with the dried tail gas containing organic matters and water vapor generated in the step S1 through low-temperature drying, and then heating and incinerating the mixture to oxidize and decompose the organic matters in the mixed gas to obtain high-temperature flue gas;

s5, waste heat recovery, namely conveying the high-temperature flue gas obtained after secondary incineration in the step S4 to an air heat exchanger for heat exchange so as to recover heat of the high-temperature flue gas and reduce the temperature of the flue gas to 180-200 ℃;

and S6, flue gas purification, namely deacidifying and denitrating the flue gas subjected to the waste heat recovery in the step S5, and discharging the treated flue gas from a chimney.

The method changes the prior method of direct atomization incineration and rapid cooling by using a large amount of water, adopts the steps of low-temperature drying, organic matter thermal desorption, high-temperature desalting, secondary incineration, waste heat recovery, flue gas purification and discharge and the like, desorbs the organic matter after the high-salt organic wastewater is dried and reduced at low temperature, realizes the separation of solid salt particles and the flue gas through the high-temperature desalting, avoids the adhesion of molten salt on a waste heat recovery device, ensures the normal operation of the waste heat recovery device, and improves the energy utilization rate due to the adoption of the modes of low-temperature drying and waste heat recovery.

The further optimized technical scheme of the invention is as follows:

in the step S1, the organic wastewater with high salt content is dried at low temperature through a roller scraper dryer, the heat source of the roller scraper dryer comes from flue gas generated by fuel combustion, the fuel is preheated and supports combustion by adopting the heat recovered from the waste heat of the step S5 during combustion, the heat conducting medium of the roller scraper dryer adopts heat conducting oil or low-pressure steam of 0.5-0.8 MPa, and the drying temperature is 100-200 ℃.

In the step S2, organic matter desorption adopts a spiral indirect heating or direct heating mode, the temperature of introduced high-temperature flue gas is 500-700 ℃, the high-temperature flue gas is from fuel combustion, and the fuel combustion adopts the heat recovered from the waste heat of the step S5 to preheat and support combustion.

In the step S3, an acid and alkali corrosion resistant ceramic fiber filter pipe is arranged in the high-temperature desalter, a group of filter holes with the aperture of 1-10 microns are formed in the filter pipe, and the filter efficiency is as high as 99.9% -99.99%.

In the step S4, the flue gas obtained after high-temperature desalination and the dry tail gas discharged after low-temperature drying in the step S1 are mixed together, the mixed flue gas is heated and incinerated in a combustion chamber, the heating and incinerating temperature is 1100-1150 ℃, and the retention time of the mixed flue gas in the combustion chamber is 2S.

The dry tail gas contains organic matters, and the flue gas may also contain incompletely decomposed organic matters, so that the complete decomposition of the organic matters can be ensured through secondary combustion. In the hazardous waste incineration specification GB18484, the flue gas generated by hazardous waste needs to stay for more than 2 seconds at the temperature of more than 1100 ℃, so that the mixed flue gas needs to stay for 2 seconds in a combustion chamber.

In the step S5, the high-temperature flue gas exchanges heat with air in an air heat exchanger to preheat the air, the temperature of the flue gas after heat exchange is reduced to 180-200 ℃, the heat of the preheated air is used for supporting combustion during fuel combustion, and the high-temperature flue gas generated by the fuel combustion is used for providing heat for low-temperature drying of S1 and organic matter desorption of S2.

The waste heat recovery device in the above steps is a gas-gas heat exchanger, the high temperature flue gas and the normal temperature air are respectively introduced into the air heat exchanger for heat exchange, the heat of the high temperature flue gas is transferred to the air, the air is preheated, and the preheated air is used as combustion-supporting air for fuel combustion. High-temperature flue gas generated after fuel combustion is used as a heat source of S1 and S2.

In the step S6, flue gas deacidification adopts a flue gas purification deacidification agent, the flue gas purification deacidification agent is sodium bicarbonate powder ground to 500 meshes, and the deacidification efficiency reaches 85-90%; the denitration process is low-temperature SCR, and the denitration agent is ammonia.

The method has the advantages that the method can simultaneously treat the salt and the organic matters in the high-salt-content wastewater, the salt can be directly recycled after the complete treatment, and the application range is wide and the method is suitable for the salt-containing organic wastewater with various concentrations. No waste water and waste gas and no secondary pollutant.

Drawings

FIG. 1 is a process flow diagram of the present invention.

FIG. 2 is a flow chart of the system of the present invention.

In the figure: 1. the system comprises a water inlet pipeline, 2 a roller scraper dryer, 3 a lifter, 4 a dry tail gas pipeline, 5a burner, 6 a thermal desorption device, 7 a high-temperature desalter, 8 a granular salt recovery pipeline, 9a secondary combustion chamber, 10 a flue gas heat exchanger, 11 a normal-temperature air pipeline, 12 a flue gas purification system and 13 a chimney.

Detailed Description

Example 1

The embodiment provides a method for treating high-salt organic wastewater, wherein the high-salt organic wastewater comes from a production line of a certain pesticide plant, the total salt content of the wastewater is 18%, the organic matter content of the wastewater is 7%, and the water content of the wastewater is 75%.

The method for disposing the high-salt-content organic wastewater, as shown in fig. 1, includes the following steps:

s1, drying at low temperature

The high-salt organic wastewater is conveyed to the roller scraper dryer 2 through the water inlet pipeline 1 by a pump, high-temperature flue gas with the temperature of 159 ℃ at 0.5MPa (G) is introduced into the roller scraper dryer 2 to carry out low-temperature drying on the high-salt organic wastewater, the water content of the dried material is 8%, and the material is solid.

The roller scraper dryer 2 dries the organic wastewater with high salt content at a low temperature, a heat source of the roller scraper dryer 2 comes from high-temperature flue gas generated by fuel combustion in the combustor 5, the fuel combustion in the combustor 5 adopts heat recovered from S5 waste heat to support combustion, heat conducting oil is adopted as a heat conducting medium of the roller scraper dryer 2, and the drying temperature is 100-200 ℃. The high temperature flue gas is at the inside conduction oil of cylinder scraper blade as the heat source heating, and the conduction oil is at cylinder internal recycle, the outside material of heating cylinder, and the cylinder incessantly rotates on containing salt waste water, heats the material on its surface, and is finally and the adhesion is scraped off by the scraper on the cylinder surface along with the material is dry, resumes dry material again. The high-temperature flue gas can also be used for generating 0.5-0.8 MPa steam through a heating boiler to circularly dry the materials in the roller. And the drying tail gas generated in the low-temperature drying process of the roller scraper dryer 2 is conveyed to a secondary combustion chamber 9 through a drying tail gas pipeline 4 for secondary combustion.

S2 desorption of organic matter

Adopt lifting machine 3 (being band conveyer) to carry the solid state material after S1 handles to thermal desorption device 6, thermal desorption device 6 adopts the screw conveyer of outband jacket, lets in 650 ℃ high temperature flue gas in its outer jacket and heats the solid state material, and organic matter and residual moisture volatilize from it and form desorption gas (being the high temperature flue gas that contains salt) among the solid state material heating process, and the residual solid-state thing is recoverable solid-state salt, and solid-state salt retrieves through granular salt recovery pipeline 8. The high-temperature flue gas required by the thermal desorption of the organic matters is generated by the combustion of the fuel of the combustor 5, and the fuel in the combustor 5 is combusted by using the preheated air after the waste heat of S5 is recovered for supporting combustion.

S3, high-temperature desalting

The desorption gas treated by the S2 enters a high-temperature desalter 7 under the pumping of a draught fan, the flue gas filters out granular salt and is recycled, the organic matter content in the filtered salt is lower than 0.3 percent, the water content is lower than 0.1 percent, and the granular salt is recycled through a granular salt recycling pipeline 8; the adsorbed gas is filtered to remove salt to form flue gas.

The high-temperature demineralizer 7 is similar to a bag-type dust remover, can be obtained by replacing a bag of the bag-type dust remover with a high-temperature ceramic tube, can resist 1200 ℃, can remove salt at high temperature, and can resist the temperature of only 200 ℃ by the bag-type dust remover.

S4, secondary incineration

The flue gas after the high-temperature desalination of S3 and the dry tail gas containing organic matters and water vapor generated by the low-temperature drying of S1 are mixed in a secondary combustion chamber 9, the mixed flue gas is heated to 1100 ℃ in the secondary combustion chamber 9 through a natural gas burner for incineration, and the mixed flue gas stays in the secondary combustion chamber 9 for 2S, so that the organic matters remained in the mixed flue gas are thoroughly oxidized and decomposed into CO₂And H₂And O, forming high-temperature flue gas.

S5 waste heat recovery

The high-temperature flue gas treated by the S4 exchanges heat with normal-temperature air sent by a normal-temperature air pipeline 11 in a flue gas heat exchanger 10 to recover heat, the temperature of the flue gas after heat exchange is reduced to 200 ℃, the air is heated to be preheated air, the heat recovered by the preheated air is used for preheating and supporting combustion when fuel is combusted in a combustor 5, and the high-temperature flue gas generated by fuel combustion heats the outer jackets of the roller scraper dryer 2 in the step S1 and the spiral conveyer in the step S2.

S6, flue gas purification

The low-temperature flue gas subjected to cooling treatment of S5 enters a flue gas purification system 12, and a dry deacidification tower of the flue gas purification system 12 performs a neutralization reaction with the sprayed and ground 500-mesh sodium bicarbonate powder to remove acidic gases such as HCl and SO in the flue gas₂And the treated flue gas is discharged from a chimney 13 after denitration.

The device used in the method of the embodiment, as shown in fig. 2, includes a roller scraper dryer 2, a lifter 3, a thermal desorption device 6, a high-temperature ceramic desalter 7, a secondary combustion chamber 9, a flue gas heat exchanger 10 and a flue gas purification system 12, wherein an inlet of the roller scraper dryer 2 is connected with a water inlet pipeline 1, a solid material outlet of the roller scraper dryer 2 is connected with a bottom inlet of the lifter 3 through a solid material conveying pipeline, and a top outlet of the lifter 3 is connected with a solid material inlet of the thermal desorption device 6 through a solid material conveying pipeline. And a dry tail gas outlet of the roller scraper dryer 2 is connected with a flue gas inlet of the secondary combustion chamber 9 through a dry tail gas pipeline. The thermal desorption device 6 is a screw conveyer with an outer jacket, and an atomization mechanism and a burner 5 are arranged on the thermal desorption device 6. The bottom of thermal desorption device 6 contains the salt high temperature exhanst gas outlet and links to each other through containing the salt high temperature flue gas entry of salt high temperature flue gas pipeline with high temperature ceramic demineralizer 7, and the exhanst gas outlet of high temperature ceramic demineralizer 7 passes through the flue gas entry that flue gas pipeline and second combustion chamber 9 and links to each other, and the bottom export of thermal desorption device 6, high temperature ceramic demineralizer 7 all connects the granular salt recovery pipeline 8. The second combustion chamber 9 is connected with a flue gas heat exchanger 10 through a high-temperature flue gas pipeline, and the flue gas heat exchanger 10 is connected with a flue gas purification system 12 through a low-temperature flue gas pipeline. Wherein, the last high temperature flue gas entry that has of gas heater 10, the low temperature exhanst gas export, normal atmospheric temperature air inlet and preheated air export, the high temperature flue gas entry passes through high temperature flue gas pipeline and the high temperature exhanst gas outlet of second combustion chamber 9 and is connected, the low temperature exhanst gas export passes through the flue gas entry that low temperature flue gas pipeline and flue gas cleaning system 12 and is connected, normal atmospheric temperature air inlet is connected with normal atmospheric temperature air pipeline 11, preheated air export passes through the inlet connection of preheated air pipeline with combustor 5, the high temperature exhanst gas export of combustor 5 is connected thermal desorption device 6 and cylinder scraper dryer 2 respectively. The outlet of the flue gas purification system 12 is connected with a chimney 13, and the flue gas purification system 12 comprises a dry deacidification tower and a desulfurization tower which are sequentially connected.

The high-salt organic water enters a roller dryer 2 through a water inlet pipeline 1, the high-salt organic water is dried until the water content is 5-10%, solid materials containing organic matters and salt are formed, the solid materials are conveyed to a thermal desorption device 6 through a lifting machine 3, the solid materials are heated to 500-700 ℃ by high-temperature flue gas generated by a burner 5 in the thermal desorption device 6, the water and the organic matters in the solid materials are completely vaporized into gaseous state through high-temperature thermal desorption, the rest small part of solid salt particles are settled in the thermal desorption device 6 and are discharged and recovered from a particle salt recovery pipeline 8, the rest water, the organic matters and the particle salt enter a high-temperature demineralizer 7 along with the flue gas, and the particle salt obtained through filtering by a ceramic fiber tube of the high-temperature demineralizer 7 enters a particle salt recovery pipeline 8 to be discharged and recovered. The flue gas filtered by the high-temperature demineralizer 7 enters a secondary combustion chamber 9, the temperature is raised to 1100 ℃, and the flue gas stays for more than 2 seconds, so that organic matters are thoroughly burnt, and the generation of dioxin is prevented. The flue gas discharged from the secondary combustion chamber 9 enters a flue gas heat exchanger 10 to exchange heat with air for cooling, and the air is used as combustion-supporting air of the combustor 5 after heat exchange and temperature rise so as to save fuel. And the cooled flue gas enters the flue gas purification system 12, and is discharged after deacidification, denitration and purification.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.