Continuous sludge thermal hydrolysis reaction kettle and method for detecting sludge retention time of continuous sludge thermal hydrolysis reaction kettle

Abstract

The invention discloses a continuous sludge thermal hydrolysis reaction kettle and a detection method for sludge retention time thereof. The reaction kettle comprises an outer-layer heating jacket and an inner-layer tank body, a sludge feeding hole is formed in the bottom of the tank body, a sludge discharging hole is formed in the upper part of the tank body, and an access hole is formed in the middle of the tank body; a stirring paddle is arranged in the tank body and is controlled by a stirring motor at the top end outside the tank body to rotate, three groups of fan blades are arranged on the stirring paddle, two groups of guide plates are arranged on the inner wall of the tank body, and the interior of the tank body is divided into an upper area, a middle area and a lower area by the guide plates. Through the synergistic effect of the stirring paddle and the guide plate, the retention time of the sludge in the reaction kettle can be effectively ensured to accord with the optimal interval in a sludge thermal hydrolysis treatment system which continuously operates, so that the sludge hydrolysis efficiency of the whole system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a continuous sludge thermal hydrolysis reactor and a method for detecting the sludge residence time thereof, and belongs to the technical field of sludge treatment and disposal. BACKGROUND

[0002] Sludge is a complex organic mixture containing a large amount of macromolecular proteins, carbohydrates and lipids, and contains a large number of microorganisms and pathogens. If the sludge is not harmfully treated, it will pose a great threat to the environment. The thermal hydrolysis technology is a kind of efficient hydrothermal treatment method, which has a significant effect on improving the dewatering and anaerobic digestion of sludge, and can maximize the resource utilization degree of sludge, effectively reduce the amount of sludge generated in the municipal wastewater treatment plant, and alleviate the end sludge treatment pressure.

[0003] The operation mode of the sludge thermal hydrolysis device is mainly divided into batch and continuous. In the existing continuous operation technology, the thermal hydrolysis reactor is limited by the design of the tank body structure. The sludge is fed from the top of the tank body. Since the specific gravity of the sludge is greater than that of water, it is difficult to ensure that the sludge in the tank has sufficient residence time to complete the hydrothermal reaction under the action of gravity. And the large particles of sludge are easy to deposit at the bottom of the hydrolysis tank. In the case of uneven stirring, the sludge hydrolysis in the hydrolysis reactor is easy to appear in the dead angle area, thereby reducing the sludge hydrolysis efficiency of the whole system. SUMMARY

[0004] The present application relates to a continuous sludge thermal hydrolysis reactor and a method for detecting the sludge residence time thereof, and belongs to the technical field of sludge treatment and disposal.

[0005] Technical solution: The continuous sludge thermal hydrolysis reactor provided by the present application comprises a tank body, a guide plate is arranged on the inner wall of the tank body, the guide plate has a structure of narrow top and wide root, the upper end and the lower end of the root of the guide plate have a certain arc, the top end of the guide plate is a conical structure, a hole is formed in the top end of the conical structure, and a stirring paddle is arranged in the tank body and extends vertically through the guide plate.

[0006] Furthermore, the curvature r1 of the upper root end of the guide plate is 25-30°, and the arc length is 40-50% of the straight-line distance from the upper cross-section endpoint of the guide plate to the tank body along the guide plate. The curvature r2 of the lower root end of the guide plate is 20-25°, and the arc length is 40-50% of the straight-line distance from the lower cross-section endpoint of the guide plate to the tank body along the guide plate. There are two or more guide plates, and the angle between the lower cross-section of the front end of the guide plate and the horizontal plane is 25-30°. The radius of the hole is 20-30% of the radius of the reactor tank body. The tank body is equipped with a heating device on the outside, which is an outer heat conduction heating jacket mounted on the tank body. The upper end of the agitator paddle passes through the top of the tank body and is equipped with a stirring motor. The agitator paddle is controlled by the stirring motor and is equipped with multiple sets of blades. The tank body has a sludge inlet at the bottom and a sludge outlet at the top. The tank body has an inspection port in the middle. Check valves are installed at both the sludge discharge port and the inlet. A pressure gauge and pressure sensor interface are located on the upper portion of the tank, connected to the pressure sensor and pressure gauge, respectively. The angle β between the upper and lower end points of the guide plate near the hole is 40-45°. The distance L between the outer diameter of the agitator paddle and the guide plate is 15-30 cm, and the angle γ between the blade and the agitator paddle is 55-65°.

[0007] A method for detecting the residence time of sludge in the continuous sludge thermal hydrolysis reactor using the present invention comprises the following steps:

[0008] (1) Sludge preparation: Add calcium oxide powder to the sludge, add water and stir to form a slurry;

[0009] (2) Sludge preheating: preheating the sludge to obtain preheated sludge, and then adding a variety of microcapsules with different rupture times at the same temperature to obtain preheated sludge;

[0010] (3) Sludge hydrolysis and flash evaporation: The preheated sludge is introduced into the continuous sludge thermal hydrolysis reactor, and the sludge is subjected to thermal hydrolysis reaction, flash evaporation, and dehydration by centrifugation under the coordinated action of the guide plate and the stirring paddle.

[0011] Furthermore, in step (2), the preparation of microcapsules includes the following steps:

[0012] (A1) Preparation of millimeter-scale paraffin template: Heat and melt paraffin, add the detection agent to the paraffin, and stir to mix thoroughly; granulate, solidify to form spheres, sieve, and dry to obtain paraffin template spheres;

[0013] (A2) Preparation of PLA / DCM solution: PLA with a molecular weight of 20 kDa-100 kDa was weighed and dissolved in dichloromethane (DCM). The solution was stirred in a water bath until completely transparent. Nano-SiO2, nano-clay, or glutaraldehyde was added and ultrasonically dispersed to obtain a PLA / DCM solution.

[0014] (A3) Shell formation by dip-coating and wall thickness control: ① Initial layer coating: the paraffin template spheres in step (A1) are dipped into a PLA / DCM solution, and after drying, an initial layer shell is formed; ② Multi-layer thickening: repeat the coating operation in step ① above until the capsule wall thickness reaches the desired thickness;

[0015] (A4) Template removal and intensive drying: the capsules are immersed in silicone oil, oil bath stirring, centrifugation, the upper layer is PLA microcapsule, the middle layer is silicone oil, and the lower layer is molten paraffin; the upper layer of PLA microcapsule is gradient dried.

[0016] Further, different detection agents are sealed in microcapsules of different wall thickness, and the microcapsules are mixed into the sludge slurry, and finally introduced into the hydrolysis reactor for hydrothermal reaction. At a predetermined heating temperature, as the heating time of the sludge is prolonged, the microcapsules of different wall thicknesses are broken in turn, so that the detection agents encapsulated therein are released into the sludge hydrolysis liquid. By quantitatively analyzing the different detection agents present in the sludge hydrolysis liquid, it is determined whether the residence time of the sludge in the hydrolysis reactor meets the optimal experimental interval.

[0017] Further, the microcapsules are made of polylactic acid (PLA) with a particle size of about 1 mm, and the controlled rupture at different time ranges under certain temperature can be realized by adjusting the molecular weight and additives.

[0018] Further, the detection agent needs to meet the following four conditions:

[0019] (1) Water-soluble, can be fully dissolved in the sludge hydrolysis liquid;

[0020] (2) Thermal stability, can withstand high temperature and remain unchanged at this temperature for at least 2 hours;

[0021] (3) Chemical stability, no chemical reaction between different detection agents, and no chemical reaction with various substances in the sludge;

[0022] (4) Easy to detect and analyze, different detection agents need to have certain distinction in the detection method used, and the characteristic elements in these detection agents do not exist or have very little content in the sludge.

[0023] Further, different detection agents and different wall thickness of microcapsules need to be one-to-one corresponding to the heating time node.

[0024] Further, the corresponding factors of regulating the wall thickness of microcapsules and rupture time are shown in the following table:

[0025]

[0026] Further, the detection agent used includes, but is not limited to, strontium chloride, lanthanum chloride, lithium chloride, rubidium chloride, cesium chloride.

[0027] Further, in step (1), the calcium oxide powder is added in an amount of 2-5wt% of the sludge mass, and the slurry has a water content of 90-95%; in step (2), the preheating temperature is 90-100 DEG C, the preheating time is 10-20 min, and the microcapsule is added in an amount of 1-5wt% of the sludge; in step (3), the temperature of the thermal hydrolysis reaction is 175-180 DEG C, the time of the thermal hydrolysis reaction is 55-65 min, the pressure in the reaction vessel during the thermal hydrolysis reaction is 1.5-2.0 Mpa, and the pressure in the flash evaporation vessel is released to normal pressure within 1-30 s after flash evaporation.

[0028] Advantages: Compared with the prior art, the present application has the following advantages: (1) The structure of the sludge thermal hydrolysis reactor of the present application is simple and reasonable, easy to operate and maintain, has high automation degree and good stability, and effectively reduces the cost and difficulty of sludge treatment. (2) The guide vane is made of glass fiber composite material, which is light in weight, resistant to high temperature and pressure, and resistant to acid and alkali corrosion. It has a simple structure, is easy to maintain, has a long service life and is not easy to deform. The structure with a certain arc at the upper and lower ends of the root can effectively reduce the sludge deposition dead zone. (3) The sludge thermal hydrolysis treatment system of the present application can effectively ensure that the residence time of the sludge in the reactor can be maintained in the optimal interval for thermal hydrolysis reaction, thereby improving the sludge hydrolysis efficiency of the whole system. (4) The sludge residence time detection method of the present application is simple, efficient and fast, and can directly show the residence of the sludge in the thermal hydrolysis reactor, thereby helping researchers to optimize the experimental scheme and reactor design parameters. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a structure schematic diagram of the continuous sludge thermal hydrolysis reactor in Example 1.

[0030] In the figure, 1 is a heating device, 2 is a tank body, 3 is a stirring motor, 4 is a pressure gauge and pressure sensor interface, 5 is a thermometer and temperature sensor interface, 6 is a discharge port, 7 is a check valve, 8 is a guide vane, 9 is a stirring paddle, 10 is a stirring paddle blade, 11 is a feed port, 12 is an access port, 13 is a reactor base and support.

[0031] Figure 2 It is a flow chart for detecting the residence time of the Wuning water reaction by using the continuous sludge thermal hydrolysis reactor in Example 1. DETAILED DESCRIPTION

[0032] The municipal sludge described in the examples was taken from a municipal domestic sewage treatment plant in Nanjing, Jiangsu Province. Its moisture content was 67%, pH was 7.2, TCOD was 95.28 g / L, C / N was 10.71, and VS / TS was 60.30%. The above values ​​are the average values ​​during this round of experiments.

[0033] Example 1

[0034] like Figure 1 As shown, the continuous sludge thermal hydrolysis reactor described in the present invention comprises a tank body 2, with a heating device 1 externally mounted on the tank body 2. The heating device 1 is an outer heat conduction heating jacket mounted on the tank body 2. Two sets of guide plates 8 are mounted on the inner wall of the tank body 2, dividing the interior of the tank body 2 into three areas: upper, middle, and lower. A stirring paddle 9 is mounted vertically inward from the top of the tank body 2, passing through the guide plates 8. The upper end of the stirring paddle 9 passes through the top of the tank body 2 and is provided with a stirring motor 3. The stirring paddle 9 is controlled by the stirring motor 3. The stirring paddle 9 is equipped with three sets of blades 10. A sludge feed inlet 11 is located at the bottom of the tank body 2, a sludge discharge port 6 is located at the top of the tank body 2, and an inspection port 12 is provided in the middle of the tank body 2. Both the sludge discharge port 6 and the feed inlet 11 are equipped with check valves 7. A pressure gauge and a pressure sensor interface 4 are mounted on the top of the tank body 2, through which a pressure sensor and a pressure gauge are connected, respectively.

[0035] The deflector 8 is a glass fiber composite partition of a certain thickness, narrow at the top and wide at the base. Both the upper and lower ends of the base have a certain curvature. The curvature r1 of the upper end of the base is 25-30 degrees, and the arc length is 40-50% of the straight-line distance from the upper cross-section endpoint of the deflector 8 to the tank body 2. The curvature r2 of the lower end of the base is 20-25 degrees, and the arc length is 40-50% of the straight-line distance from the lower cross-section endpoint of the deflector 8 to the tank body 2. The conical tip of the deflector 8 has a hole, and the radius of the hole is 20-30% of the radius of the tank body 2. The angle α between the lower cross-section of the front end of the deflector 8 and the horizontal plane is 25-30 degrees, and the angle β between the upper and lower cross-section endpoints of the deflector 8 near the hole is 40-45 degrees. The distance L between the outer diameter of the stirring paddle 9 and the guide plate 8 is 15-30 cm, and the angle γ between the fan blade 10 and the stirring paddle 9 is 55-65°.

[0036] The method for detecting the residence time of sludge in the continuous sludge thermal hydrolysis reactor using the above-mentioned reactor comprises the following steps:

[0037] (1) Sludge preparation: Add calcium oxide powder to the sludge, add water and stir to form a slurry;

[0038] (2) Sludge preheating: The sludge is heated to obtain preheated sludge, and then a variety of microcapsules with different rupture times at the same temperature are added to obtain preheated sludge;

[0039] (3) Sludge hydrolysis flash: the preheated sludge is introduced into the above-mentioned sludge thermal hydrolysis reactor, and the sludge is subjected to thermal hydrolysis reaction in the reactor under the synergistic action of the guide plate 8 and the stirring paddle 9, and then is subjected to flash and dewatering centrifugation of the remaining material. The whole process is shown in Figure 2 .

[0040] The microcapsule synthesis method is as follows:

[0041] (1) Millimeter paraffin template preparation: ① Respectively take an appropriate amount of paraffin and divide it into 5 groups in equal parts, heat the paraffin to 70℃ to completely melt, then add 0.1%wt of different detection agents (metal ion chloride salt, respectively strontium chloride, lanthanum chloride, lithium chloride, rubidium chloride, cesium chloride) to the 1-5 group paraffin and stir well; then pour the liquid paraffin into the template granulation device, make the liquid drops drop vertically into 0-5℃ ice water (the injection pump propelling speed is 5mL / h, the needle head is 15cm away from the water surface), solidify to form spheres; ② Collect the template spheres through 16 mesh (1250μm) and 18 mesh (1000μm) standard screens in turn, and collect the template spheres with the required particle size (1000μm < template sphere particle size < 1250μm), and dry the collected template spheres in a drying box at 40℃ for 2h for standby.

[0042] (2) PLA solution preparation: respectively take an appropriate amount of PLA with a molecular weight of 20kDa-100kDa and dissolve it in dichloromethane (DCM), control the solution concentration to be 8%-12%w / v, mark it as No.1-5, and use a magnetic stirring device to stir in a 40℃ water bath at 500rpm until the solution is completely transparent; then add 0.5%wt of nano SiO2, 1%wt of nano SiO2, 0.5%wt of nano clay, 1%wt of nano clay and 0.2%wt of glutaraldehyde to No.1-5 solution respectively; ultrasonic dispersion (100W, 10min) is carried out for No.1-4 solution under the condition of ice bath, and No.5 solution continues to be stirred at 40℃ water bath, 500rpm for 30min to activate crosslinking.

[0043] (3) Shell formation by immersion coating and wall thickness control: ① Initial layer coating: the five groups of paraffin template spheres dried in step (1) are respectively fixed in the rotating clamp (20rpm), then immersed in the corresponding numbered PLA / DCM solution for 10s, then slowly lifted to above the liquid surface (speed 2mm / s), and after drying, the initial layer shell is formed; ② Multi-layer thickening: repeat the above coating operation until the capsule wall thickness reaches the required thickness (each coating can increase the thickness by about 10μm).

[0044] (4) Template removal and reinforced drying: ①Melt removal of paraffin wax: after coating, the capsules were immersed in silicone oil in an oil bath at 60°C and mechanically stirred for 30 min (100 rpm). After stirring, centrifugation was performed for 15 min (5000 rpm). The upper layer was PLA microcapsules, the middle layer was silicone oil (reused after filtration), and the lower layer was molten paraffin wax (recycled).

[0045] (5) Wall thickness verification: the microcapsules obtained in step (4) were fixed on a sample stage, and the wall thickness was measured by scanning with a micro-CT method, and the mean value and dispersion (SD < 8% is qualified) were calculated.

[0046] The types of the obtained microcapsules are shown in Table 1 as follows:

[0047] Table 1 Related parameters of microcapsules

[0048]

[0049] Example 2

[0050] The continuous sludge thermal hydrolysis reactor of Example 1 was used to detect the residence time of sludge in the reactor, as follows:

[0051] The upper end of the root has an arc r1 of 30°, and the arc length is 50% of the straight-line distance from the end point of the upper section of the guide plate 8 to the tank body 2. The lower end of the root has an arc r2 of 25°, and the arc length is 50% of the straight-line distance from the end point of the lower section of the guide plate 8 to the tank body 2. The radius of the hole of the guide plate 8 is 20% of the radius of the reactor tank body 2. The angle a between the lower section of the guide plate in the sludge thermal hydrolysis reactor and the horizontal plane is 30°. The angle β between the end point of the upper section of the guide plate near the hole and the end point of the lower section is 45°. The distance L between the outer diameter of the stirring paddle and the guide plate is 15 cm. The angle γ between the fan and the stirring paddle is 60°.

[0052] (1) Sludge preparation: municipal sludge with a water content of 67% was put into a slurrying tank, then calcium oxide powder with a proportion of 2% of the mass of the sludge was added, and water was added to prepare a slurry with a water content of 95%;

[0053] (2) Sludge preheating: the slurry was heated to 100°C in a preheating tank to obtain preheated sludge. At this time, five kinds of microcapsules were added to the preheating tank, and the addition amount of different kinds of microcapsules was consistent and was 1 wt% of the sludge addition amount;

[0054] (3) Sludge hydrolysis flash: the sludge preheated by the adjustment is fed into the sludge thermal hydrolysis reactor, and the sludge is kept in the reactor at 180°C for 1 h under the cooperation of the guide plate 8 and the stirring paddle 9 to complete the basic thermal hydrolysis reaction; the sludge after the reaction is transported to the flash tank for flash evaporation, and the pressure in the flash tank at this time is 1.8 MPa as read by the pressure gauge, the pressure relief exhaust valve is opened to relieve pressure, and the pressure in the flash tank drops to normal pressure within 20 s, and after the flash evaporation is completed, the material in the flash tank is discharged and dehydrated by centrifugation.

[0055] The sludge cake moisture content is measured after the material discharged from the flash tank in step (3) is dehydrated and centrifuged, and the COD, ammonia nitrogen and total nitrogen of the remaining hydrolysis liquid are measured; the measurement results are as follows: the sludge cake moisture content is 34%, the COD value of the hydrolysis liquid is 75500 mg / L, the ammonia nitrogen value is 2177 mg / L, and the total nitrogen value is 6588 mg / L. After the hydrolysis liquid is pretreated to eliminate interference, the atomic absorption spectrometry (AAS) is used to detect the concentration ratio of the five detection agents contained in the hydrolysis liquid, and the detection results are shown in Table 2.

[0056] Table 2 Detection ratio of different detection agents in sludge hydrolysis liquid of Example 2

[0057]

[0058] From Table 2, it can be seen that the ①-④ detection agents are all detected, but the ④ detection agent has a very low ratio, and the ③ detection agent has a detection ratio close to that of ① and ②, that is, the first three microcapsules have been completely broken and released their contained detection agents in the thermal hydrolysis reaction, while the ④ and ⑤ microcapsules have almost not cracked. This shows that the residence time interval of the sludge in the thermal hydrolysis reactor in this round of experiment is concentrated in 60 min (optimal residence time).

[0059] Comparative Example 1

[0060] The only difference between Comparative Example 1 and Example 2 is that the angle α between the lower cross section of the guide plate in the sludge thermal hydrolysis reactor and the horizontal plane is 0°.

[0061] The sludge cake moisture content is measured after the material discharged from the flash tank in step (3) is dehydrated and centrifuged, and the COD, ammonia nitrogen and total nitrogen of the remaining hydrolysis liquid are measured; the measurement results are as follows: the sludge cake moisture content is 42%; the COD value of the hydrolysis liquid is 65000 mg / L, the ammonia nitrogen value is 1893 mg / L, and the total nitrogen value is 5766 mg / L. After the hydrolysis liquid is pretreated to eliminate interference, the atomic absorption spectrometry (AAS) is used to detect the concentration ratio of the five detection agents contained in the hydrolysis liquid, and the detection results are shown in Table 3.

[0062] Table 3 Detection ratio of different detection agents in sludge hydrolysis liquid of Comparative Example 1

[0063]

[0064] From Table 3, it can be seen that the detection agents No. 1-3 were detected and the detection ratios gradually decreased, and the detection agents No. 4 and 5 were not detected, that is, the microcapsules No. 1 were basically completely lysed, the microcapsules No. 2 and 3 were only partially lysed, and the microcapsules No. 4 and 5 did not occur lysis. This indicates that the residence time interval of the sludge in the thermal hydrolysis reactor in this round of experiment is concentrated in 30 min, which is less than the optimal residence time. The reason for this phenomenon may be that, compared with Example 1, the α angle of the guide plate in Comparative Example 1 is smaller, and the lifting rate of the sludge in the reactor is too large, so that most of the sludge has not been sufficiently subjected to hydrothermal reaction and is lifted to the outlet by the stirring paddle, and then enters the flash tank.

[0065] Comparative Example 2

[0066] The only difference between Comparative Example 2 and Example 2 is that the angle α between the lower cross section of the guide plate in the sludge thermal hydrolysis reactor and the horizontal plane is 60°.

[0067] After the experiment, it was found that there was a sludge deposition dead zone at the guide plate and the inner wall of the tank through the reactor maintenance opening. After the material discharged from the flash tank in step (3) was dewatered and centrifuged, the moisture content of the sludge cake was measured, and the COD, ammonia nitrogen and total nitrogen of the remaining hydrolysis liquid were measured; the measurement results are as follows: the moisture content of the sludge cake is 55%; the COD value of the hydrolysis liquid is 48500 mg / L, the ammonia nitrogen value is 1414 mg / L, and the total nitrogen value is 4277 mg / L. After the hydrolysis liquid is pretreated to exclude interference, the atomic absorption spectrometry (AAS) is used to detect the concentration ratio of the five detection agents contained in the hydrolysis liquid, and the detection results are shown in Table 4 as follows.

[0068] Table 4 Detection ratio of different detection agents in sludge hydrolysis liquid of Comparative Example 2

[0069]

[0070] From Table 4, it can be seen that the detection agents No. 1-5 were detected, and the detection ratios of the detection agents No. 1-3 were consistent, that is, the microcapsules No. 1-3 were completely lysed to release the detection agents contained therein, part of the microcapsules No. 4 was lysed, and a small part of the microcapsules No. 5 was broken. This indicates that the residence time interval of the sludge in the thermal hydrolysis reactor in this round of experiment is concentrated in 75 min, which is greater than the optimal residence time. The reason for this phenomenon may be that the α angle of the guide plate in Comparative Example 2 is larger, and the lifting rate of the sludge in the reactor is insufficient, which leads to that the material entering the flash tank is mainly water; and the upper cross section of the guide plate forms a sludge dead zone with the inner wall of the reactor, and a large amount of sludge is deposited there and is continuously heated, which causes the Maillard reaction of the sludge, and greatly reduces the overall hydrolysis efficiency of the system.

[0071] Comparing the determination results of example 2 with those of comparative example 1 and comparative example 2, it is found that the water content of the sludge cake of example 2 is reduced by 8% and 21% respectively compared with those of comparative example 1 and comparative example 2. The COD value, ammonia nitrogen value and total nitrogen value of the hydrolysis liquid of example 2 are increased by 16.15%, 15.00% and 14.26% respectively compared with those of comparative example 1, and are increased by 55.67%, 53.96% and 54.03% respectively compared with those of comparative example 2. The residence time interval of the sludge in example 2 is concentrated in the optimal reaction time (60 min), the residence time interval of the sludge in comparative example 1 is less than the optimal reaction time, and the residence time interval of the sludge in comparative example 2 is much greater than the optimal reaction time. The optimal parameter of the included angle alpha between the lower cross section of the flow guide plate in the sludge thermal hydrolysis reactor and the horizontal plane should be 30°

[0072] In summary, the continuous sludge thermal hydrolysis reactor of the present application can effectively ensure that the sludge in the reactor has sufficient residence time for thermal hydrolysis reaction, thereby improving the sludge hydrolysis efficiency and degree of the whole system, and has good performance for municipal sludge treatment, and can realize the reduction and resource utilization of municipal sludge treatment. The detection method for sludge residence time disclosed by the present application is simple, efficient and fast, and can intuitively show the residence of the sludge in the thermal hydrolysis reactor, thereby helping researchers to optimize the experimental scheme and the design parameters of the reactor.

Claims

1. A continuous sludge thermal hydrolysis reactor, comprising a tank body (2), characterized in that: A guide plate (8) is provided on the inner wall of the tank body (2). The guide plate (8) has a narrow top and a wide root. The upper and lower ends of the root both have a certain curvature. The top of the guide plate (8) is a conical structure with a hole formed on the top. A stirring paddle (9) is provided on the top of the tank body (2) extending vertically inward through the guide plate (8).

2. The continuous sludge thermal hydrolysis reactor according to claim 1, characterized in that: The arc angle r1 of the upper end of the root of the guide plate (8) is 25-30 degrees, and the arc length is 40-50% of the straight line distance from the end point of the upper cross section of the guide plate (8) to the tank body (2) along the guide plate (8).

3. The continuous sludge thermal hydrolysis reactor according to claim 1, characterized in that: The arc angle r2 of the root lower end of the guide plate (8) is 20-25 degrees, and the arc length is 40-50% of the straight line distance from the end point of the lower cross section of the guide plate (8) to the tank body (2).

4. The continuous sludge thermal hydrolysis reactor according to claim 1, characterized in that: The guide plates (8) are provided in two or more groups, the angle (α) between the lower section of the front end of the guide plates (8) and the horizontal plane is 25-30°, and the radius of the hole is 20-30% of the radius of the tank body (2).

5. The continuous sludge thermal hydrolysis reactor according to claim 1, characterized in that: The upper end of the stirring paddle (9) passes through the upper part of the tank body (2) and is provided with a stirring motor (3). The stirring paddle (9) is controlled to rotate by the stirring motor (3). The stirring paddle (9) is provided with multiple groups of fan blades (10).

6. The continuous sludge thermal hydrolysis reactor according to claim 1, characterized in that: A heating device (1) is provided on the outside of the tank body (2), a sludge feed port (11) is provided on the bottom of the tank body (2), a sludge discharge port (6) is provided on the top of the tank body (2), and an inspection port (12) is provided in the middle of the tank body (2).

7. The continuous sludge thermal hydrolysis reactor according to claim 6, characterized in that: The angle (β) between the upper cross-section endpoint and the lower cross-section endpoint of the guide plate (8) near the hole is 40-45°; the distance (L) between the outer diameter of the stirring paddle (9) and the guide plate (8) is 15-30 cm, and the angle (γ) between the fan blade (10) and the stirring paddle (9) is 55-65°.

8. A method for detecting the residence time of sludge in the continuous sludge thermal hydrolysis reactor according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Sludge preparation: Add calcium oxide powder to the sludge, add water and stir to form a slurry; (2) Sludge preheating: preheating the sludge to obtain preheated sludge, and then adding a variety of microcapsules with different rupture times at the same temperature to obtain preheated sludge; (3) Sludge hydrolysis and flash evaporation: The preheated sludge is introduced into the continuous sludge thermal hydrolysis reactor, and the sludge is subjected to thermal hydrolysis reaction, flash evaporation, and dehydration centrifugation under the coordinated action of the guide plate (8) and the stirring paddle (9).

9. The detection method according to claim 8, characterized in that In step (2), the preparation of microcapsules includes the following steps: (A1) Preparation of millimeter-scale paraffin template: Heat and melt paraffin, add the detection agent to the paraffin, and stir to mix thoroughly; granulate, solidify to form spheres, sieve, and dry to obtain paraffin template spheres; (A2) Preparation of PLA / DCM solution: PLA was weighed and dissolved in dichloromethane. The solution was stirred in a water bath until completely transparent. Nano-SiO2, nano-clay, or glutaraldehyde was added and dispersed by ultrasonication to obtain a PLA / DCM solution. (A3) Dip-coating to form the shell and control the wall thickness: ① Initial coating: Dip the paraffin template spheres from step (A1) into the PLA / DCM solution and dry to form the initial shell layer; ② Multi-layer thickening: Repeat step ① above until the capsule wall thickness reaches the desired thickness; (A4) Template removal and enhanced drying: The capsules were immersed in silicone oil, stirred in an oil bath, and centrifuged. The upper layer consisted of PLA microcapsules, the middle layer consisted of silicone oil, and the lower layer consisted of molten paraffin. The upper layer of PLA microcapsules was then gradient dried.

10. The detection method according to claim 8, characterized in that In step (1), the amount of calcium oxide powder added is 2-5wt% of the sludge mass, and the water content of the sludge is 90-95%; in step (2), the preheating temperature is 90-100°C, the preheating time is 10-20 minutes, and the amount of microcapsules added is 1-5wt% of the sludge addition amount; in step (3), the temperature of the thermal hydrolysis reaction is 175-180°C, the thermal hydrolysis reaction time is 55-65 minutes, the pressure in the reaction vessel during the thermal hydrolysis reaction is 1.5-2.0 MPa, and after flash evaporation, the pressure in the flash evaporation vessel is released to normal pressure within 1-30 seconds.

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