Sludge drying incineration process

Abstract

The invention discloses a sludge drying and incinerating process, which relates to the technical field of sludge drying and incinerating, and is characterized in that a liquid-phase solvent and dewatered sludge are respectively added into a first-stage drying device, a second-stage drying device and a third-stage drying device according to a certain proportion, and moisture in the sludge is gradually evaporated in a water vapor form by adopting a vacuum device and a heating measure; transferring the water vapor to a next-stage drying device in the liquid-phase solvent, condensing the water vapor into water through the heat exchange device, and collecting the water; after the water content of the sludge is reduced to a preset value, introducing the materials in the dryers into solid-liquid separation equipment, and separating dried sludge particles and a liquid-phase solvent; wherein the liquid-phase solvent flows back to the drying device, dried sludge particles are fed into the incinerator to be incinerated, and steam generated in the incineration process is recycled to the first-stage drying device through a pipeline, so that the problems of dust dissipation and equipment scaling in a traditional drying process are effectively avoided, and cyclic utilization of heat energy and substances is realized.

Description

Technical Field

[0001] The invention relates to the technical field of sludge drying and incineration, in particular to a sludge drying and incineration process. Background Art

[0002] Sludge incineration is currently the most thorough way to dispose of sludge, but the high water content of sludge limits its direct incineration. It is generally necessary to cooperate with the previous sludge dehydration to reduce the sludge moisture content to meet the incineration requirements; conventional sludge dehydration generally uses hot air, steam or electricity as energy for thermal drying or chemical plate and frame flocculation drying or spray drying.

[0003] When the thermal drying method is adopted, when the sludge drying moisture content is less than 30%, a large amount of dust will be generated, and the drying equipment will be seriously scaled, which not only poses a safety risk, but also increases the investment in dust control and the processing cost; the moisture content of the sludge after the agent plate frame flocculation drying can only be reduced to 50% to 60%, and the calorific value of the sludge after drying is reduced due to the increase in the dry mass of the sludge due to the addition of the agent, and the presence of the agent is not conducive to incineration disposal. The pH value of the sewage generated during drying and dehydration is high, which increases the sewage treatment cost; spray drying is sensitive to mechanical impurities in the sludge, and the nozzle is easily blocked and worn; in the drying process, since the reaction medium is liquid, there will be no scaling problem of the equipment. Conventional drying processes and equipment, because the sludge is in direct contact with the equipment, are prone to scaling on the inner wall and surface of the equipment during long-term operation, which reduces the heat transfer efficiency, thereby reducing the processing capacity of the equipment and increasing the cost; therefore, a sludge drying and incineration process is urgently needed to solve such problems. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] The invention provides a sludge drying and incineration process to solve the problem that in a conventional drying process, dust is generated during the process and water is needed to wash the dust, which increases the sewage discharge amount and the treatment cost.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The embodiment of the present invention provides a sludge drying and incineration process, which comprises:

[0008] Step S1, adding a liquid phase solvent into the primary dryer, and adding dehydrated sludge at 1 / 4 to 1 / 2 of the amount of the liquid phase solvent, while starting a stirring device and a vacuum device, and adjusting the vacuum degree in the primary dryer by adjusting a regulating valve in a vacuum pipeline;

[0009] Step S2, applying steam or electric heating to the material in the primary dryer to evaporate the water in the sludge, and the generated water vapor is transferred to the secondary dryer via a liquid solvent;

[0010] Step S3, adding liquid phase solvent and sludge in the same proportion as in step S1 into the secondary dryer, starting the stirring device and the vacuum device, and using the water vapor transmitted from the primary dryer to heat the material in the secondary dryer, so that the water in the sludge evaporates in the secondary dryer, and the water vapor is transmitted to the tertiary dryer through the liquid phase solvent;

[0011] Step S4, after adding the liquid solvent and the sludge into the third-stage dryer, the stirring device and the vacuum device are started, and the water vapor transmitted from the second-stage dryer is used to heat the material in the third-stage dryer, and the water vapor is condensed through the heat exchange device;

[0012] Step S5, discharging the materials in each level of dryers and introducing them into a solid-liquid separation device, separating the dried sludge particles from the liquid phase solvent to obtain dried sludge particles, wherein the liquid phase solvent flows back to the dryer.

[0013] As a preferred embodiment of the sludge drying and incineration process described in the present invention, in step S5, the separated dried sludge particles are sent to an incinerator for incineration, and the steam generated during the incineration process is sent to a primary dryer as a heat source.

[0014] As a preferred solution of the sludge drying and incineration process described in the present invention, the liquid phase solvent is an alkane or a hydrocarbon mixture.

[0015] As a preferred solution of the sludge drying and incineration process described in the present invention, the amount of sludge added to the first-stage, second-stage and third-stage dryers is 1 / 4 to 1 / 2 of the amount of liquid phase solvent added.

[0016] As a preferred scheme of the sludge drying and incineration process described in the present invention, the vacuum degree in each stage of the dryer increases successively, the vacuum degree of the second stage dryer is higher than that of the first stage dryer, and the vacuum degree of the third stage dryer is higher than that of the second stage dryer.

[0017] As a preferred scheme of the sludge drying and incineration process described in the present invention, the heating temperatures in each stage of the dryer are respectively controlled as follows: 90℃~95℃ for the first stage dryer, 80℃~85℃ for the second stage dryer, and 60℃~65℃ for the third stage dryer.

[0018] As a preferred scheme of the sludge drying and incineration process described in the present invention, the vacuum degrees in each stage of the dryer are respectively controlled as follows: the first stage dryer is -0.05MPa to -0.02MPa, the second stage dryer is -0.08MPa to -0.05MPa, and the third stage dryer is -0.11MPa to -0.08MPa.

[0019] As a preferred solution of the sludge drying and incineration process described in the present invention, the process also includes collecting and measuring the condensed water generated in each stage of the drying process.

[0020] As a preferred solution of the sludge drying and incineration process described in the present invention, the rotation speed of the stirring operation in each stage of the dryer is 10r / min to 20r / min.

[0021] As a preferred solution of the sludge drying and incineration process described in the present invention, the solid-liquid separation equipment is a cyclone or a centrifuge.

[0022] The beneficial effects of the present invention are as follows: the present invention uses a liquid solvent as a medium to place the sludge in the liquid solvent, and during the heating process, the moisture in the sludge overflows from the liquid solvent in the form of water vapor, which is convenient for secondary utilization after collection;

[0023] The drying process of the present invention is carried out in a closed reactor and will not cause pollution to the surrounding environment;

[0024] The drying process of the present invention is carried out in a closed reactor, which can withstand positive pressure or negative pressure. The secondary steam generated in the drying process is easy to collect to realize waste heat utilization. This patent provides a three-level utilization mode, which can save 2 / 3 of the heat energy compared with the conventional drying process.

[0025] The drying process of the present invention is carried out in a liquid solvent, and no dust is generated;

[0026] During the drying process of the present invention, the sludge undergoes a polycondensation reaction while losing water, and naturally shrinks into uniform small spherical particles, which are convenient for later transportation and incineration; the moisture content of the sludge after drying can be reduced to as low as 2%, which is much lower than the conventional drying process; at the same time, the organic matter components can be retained in the dried sludge to a greater extent, so that the calorific value of the sludge is higher, and the low calorific value is greater than 4000 kcal / kg, which is much higher than the calorific value of the sludge after drying by conventional drying processes and equipment, and can be used as a substitute for coal to achieve resource utilization and carbon emission reduction.

[0027] In summary, the sludge drying and incineration process of the present invention performs multi-stage drying on the dehydrated sludge in a liquid solvent medium, utilizes the vacuum and heating measures in each dryer to evaporate the water in the sludge step by step, and condenses and collects it through a heat exchange device; the sludge particles formed in each stage of the dryer are uniformly spherical, and are directly sent to the incinerator for treatment after solid-liquid separation, and the steam generated by incineration is reused in the drying process, which effectively avoids the dust emission and equipment scaling problems in the traditional drying process and realizes the recycling of heat energy and materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the process of sludge drying and incineration of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1, reference Figure 1 , which is the first embodiment of the present invention, provides a sludge drying and incineration process, comprising the following steps:

[0034] 1. Primary drying stage

[0035] a. In the primary dryer, first add mineral oil and dehydrated sludge, the weight ratio of liquid solvent to sludge is 2:1, 4 tons of sludge with a water content of 80% and 8 tons of mineral oil;

[0036] b. Start the stirring device and vacuum device, the stirring speed is 10r / min, and adjust the vacuum degree in the first-stage dryer to -0.02MPa by adjusting the regulating valve on the vacuum pipeline;

[0037] c. The mixture in the primary dryer is heated by steam heating. The temperature in the primary dryer is controlled at 94°C, so that the water in the sludge escapes in the form of water vapor, and the water vapor is transferred to the secondary dryer through the liquid solvent medium;

[0038] 2. Secondary drying stage

[0039] a. In the secondary dryer, add liquid solvent and sludge with a water content of 80%, 2.6 tons of sludge and 5.2 tons of mineral oil in a ratio of 2:1 by weight of liquid solvent to sludge;

[0040] b. Start the stirring device and vacuum device, and adjust the vacuum degree in the secondary dryer to -0.05MPa;

[0041] c. Use the water vapor transmitted by the primary dryer to heat the materials in the secondary dryer, so that the water in the sludge is further converted into water vapor. The generated water vapor condenses into condensed water after releasing heat and is collected;

[0042] d. The temperature in the secondary dryer is controlled at 82°C;

[0043] 3. Three-stage drying

[0044] a. Add liquid solvent and sludge with a water content of 80%, 2 tons of sludge and 4 tons of mineral oil in the same proportion in the three-stage dryer;

[0045] b. Start the stirring device and vacuum device, and adjust the vacuum degree in the three-stage dryer to -0.08MPa;

[0046] c. The materials in the third-stage dryer are heated by the water vapor transmitted from the second-stage dryer, and the temperature in the third-stage dryer is controlled at 60°C;

[0047] d. Condensing the generated water vapor through a heat exchange device and collecting the condensed water;

[0048] 4. Solid-liquid separation and incineration stage

[0049] a. After multi-stage drying, when the moisture content of the sludge drops to the set value of 10%, the materials in each dryer are discharged and sent to the cyclone for solid-liquid separation;

[0050] b. The separated liquid solvent is returned to each dryer through a recovery device;

[0051] c. The separated dried sludge particles are sent to the incinerator for incineration;

[0052] d. The steam generated during the incineration process is transported to the first-stage dryer through a pipeline and used as a heating source to participate in the subsequent drying steps.

[0053] Example 2 is the second example of the present invention. Based on Example 1, the liquid phase solvent and operating parameters are adjusted as follows:

[0054] 1. Primary drying stage

[0055] a. In the primary dryer, operate at a weight ratio of sludge to liquid solvent of 1:2, add 4 tons of sludge with a water content of 80% and 8 tons of low-viscosity alkane mixed liquid solvent;

[0056] b. Start the stirring device, set the stirring speed to 10r / min, start the vacuum device at the same time, and adjust the vacuum degree in the first-stage dryer to -0.03MPa;

[0057] c. Use steam heating to control the temperature in the primary dryer at 95°C, so that the moisture in the sludge is converted into water vapor, which is transferred to the secondary dryer through the liquid solvent medium;

[0058] 2. Secondary drying stage

[0059] a. In the secondary dryer, add materials at a weight ratio of sludge to liquid solvent of 1:2, adding 2.6 tons of sludge with a moisture content of 80% and 5.2 tons of liquid solvent;

[0060] b. Start the stirring device and vacuum device, and adjust the vacuum degree in the secondary dryer to -0.06MPa;

[0061] c. Using the steam transmitted from the primary dryer to heat, the temperature in the secondary dryer is controlled at 83°C, so that the water in the sludge evaporates, and the generated steam condenses after releasing heat and the condensed water is collected;

[0062] 3. Three-stage drying

[0063] a. Add materials in the same proportion into the three-stage dryer, add 2 tons of sludge with a moisture content of 80% and 4 tons of liquid solvent;

[0064] b. Start the stirring and vacuum devices, and adjust the vacuum degree in the three-stage dryer to -0.09MPa;

[0065] c. Use the steam transmitted by the secondary dryer to heat and control the temperature in the third-stage dryer at 61°C;

[0066] d. Condensing the water vapor into condensed water through a heat exchange device, and collecting the condensed water;

[0067] 4. Solid-liquid separation and incineration stage

[0068] a. When the moisture content of the sludge in the material after multi-stage drying drops to the set value, the material in each dryer is discharged and sent to the solid-liquid separation equipment for solid-liquid separation;

[0069] b. The liquid solvent obtained after separation is returned to each dryer through a reflux device;

[0070] c. The separated dried sludge is sent to the incinerator for incineration, and the steam generated during the incineration process is transported to the first-stage dryer through a pipeline as a heat source.

[0071] Experimental example

[0072] The dried sludge obtained in Example 1 and Example 2 were collected for field test, wherein:

[0073] The standard test method for urban sewage sludge (refer to CJ / T 221-2023) is used to test the moisture content of the collected dried sewage sludge samples;

[0074] The calorific value of coal was determined by the method of measuring the calorific value of coal (refer to GB / T 213), and the combustion calorific value of the collected dried sludge samples was tested to obtain the low calorific value data;

[0075] The diameter distribution of the collected dried sludge samples was measured using a laser particle size analyzer, and the ash content of the collected dried sludge samples was measured with reference to the industrial analysis method for coal and water-coal slurry in GB / T212-2008; the test results are shown in Table 1:

[0076] Table 1:

[0077]

[0078] The data in Table 1 are all average values ​​collected after stable operation of each embodiment;

[0079] Combined with the test results in Table 1, it is shown that both embodiments can obtain dried sludge with a moisture content of less than 2% and a lower calorific value of more than 4000 kcal / kg, which proves the stability and repeatability of the process of the present invention under different parameter conditions;

[0080] Whether the mineral oil of Example 1 or the low-viscosity alkane mixed liquid phase solvent of Example 2 is used, the water content of the sludge can be reduced to less than 2%, and the effective recycling of the liquid phase solvent can be achieved;

[0081] In summary, the present invention uses a liquid solvent as a medium to place the sludge in the liquid solvent. During the heating process, the moisture in the sludge overflows from the liquid solvent in the form of water vapor, which is convenient for secondary utilization after collection.

[0082] The drying process is carried out in a closed reactor and will not pollute the surrounding environment;

[0083] The drying process is carried out in a closed reactor, which can withstand positive pressure or negative pressure. The secondary steam generated in the drying process is easy to collect to realize waste heat utilization. This patent provides a three-level utilization mode, which can save 2 / 3 of the heat energy compared with the conventional drying process.

[0084] The drying process is carried out in a liquid solvent and no dust is generated;

[0085] During the drying process, the sludge loses water and undergoes a polycondensation reaction, naturally shrinking into uniform small spherical particles, which are convenient for later transportation and incineration.

[0086] The moisture content of the sludge after drying can be reduced to as low as 2%, which is much lower than that of the conventional drying process. At the same time, the organic matter components can be retained in the dried sludge to a greater extent, making the calorific value of the sludge higher. The low calorific value is >4000 kcal / kg, which is much higher than the calorific value of the sludge after drying by conventional drying processes and equipment. It can be used as a substitute for coal to achieve resource utilization and carbon emission reduction.

[0087] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A sludge drying and incineration process, characterized in that: include, Step S1, adding a liquid phase solvent into the primary dryer, and adding dehydrated sludge at 1 / 4 to 1 / 2 of the amount of the liquid phase solvent, while starting a stirring device and a vacuum device, and adjusting the vacuum degree in the primary dryer by adjusting a regulating valve in a vacuum pipeline; Step S2, applying steam or electric heating to the material in the primary dryer to evaporate the water in the sludge, and the generated water vapor is transferred to the secondary dryer via a liquid solvent; Step S3, adding liquid phase solvent and sludge in the same proportion as in step S1 into the secondary dryer, starting the stirring device and the vacuum device, and using the water vapor transmitted from the primary dryer to heat the material in the secondary dryer, so that the water in the sludge evaporates in the secondary dryer, and the water vapor is transmitted to the tertiary dryer through the liquid phase solvent; Step S4, after adding the liquid solvent and the sludge into the third-stage dryer, the stirring device and the vacuum device are started, and the water vapor transmitted from the second-stage dryer is used to heat the material in the third-stage dryer, and the water vapor is condensed through the heat exchange device; Step S5, discharging the materials in each level of dryers and introducing them into a solid-liquid separation device, separating the dried sludge particles from the liquid phase solvent to obtain dried sludge particles, wherein the liquid phase solvent flows back to the dryer.

2. A sludge drying and incineration process as claimed in claim 1, characterized in that: In step S5, the separated dried sludge particles are sent to an incinerator for incineration, and the steam generated during the incineration process is sent to the primary dryer as a heat source.

3. A sludge drying and incineration process as claimed in claim 1, characterized in that: The liquid phase solvent is an alkane or a hydrocarbon mixture.

4. A sludge drying and incineration process as claimed in claim 1, characterized in that: The amount of sludge added to the primary, secondary and tertiary dryers is 1 / 4 to 1 / 2 of the amount of liquid phase solvent added.

5. The sludge drying and incineration process according to claim 1, characterized in that: The vacuum degree in each stage of the dryer increases successively, the vacuum degree of the second-stage dryer is higher than that of the first-stage dryer, and the vacuum degree of the third-stage dryer is higher than that of the second-stage dryer.

6. A sludge drying and incineration process as claimed in claim 1, characterized in that: The heating temperatures in each level of the dryer are controlled as follows: 90°C to 95°C for the first level dryer, 80°C to 85°C for the second level dryer, and 60°C to 65°C for the third level dryer.

7. The sludge drying and incineration process according to claim 1, characterized in that: The vacuum degree in each stage of the dryer is controlled as follows: the first stage dryer is -0.05MPa to -0.02MPa, the second stage dryer is -0.08MPa to -0.05MPa, and the third stage dryer is -0.11MPa to -0.08MPa.

8. The sludge drying and incineration process according to claim 1, characterized in that: The process also includes the collection and metering of condensed water produced during each stage of drying.

9. The sludge drying and incineration process according to claim 1, characterized in that: The speed of the stirring operation in each level of dryer is 10r / min~20r / min.

10. The sludge drying and incineration process according to claim 1, characterized in that: The solid-liquid separation equipment is a cyclone or a centrifuge.

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