CN112094015A - Continuous sludge pyrohydrolysis system and process capable of efficiently and fully pyrohydrolyzing - Google Patents
Continuous sludge pyrohydrolysis system and process capable of efficiently and fully pyrohydrolyzing Download PDFInfo
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- CN112094015A CN112094015A CN202010903121.2A CN202010903121A CN112094015A CN 112094015 A CN112094015 A CN 112094015A CN 202010903121 A CN202010903121 A CN 202010903121A CN 112094015 A CN112094015 A CN 112094015A
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/10—Treatment of sludge; Devices therefor by pyrolysis
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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Abstract
The invention provides a continuous sludge pyrohydrolysis system and a continuous sludge pyrohydrolysis process capable of efficiently and fully pyrohydrolyzing, wherein the system comprises a sludge bin, a discharge hole of the sludge bin is connected with a grinding pump, the grinding pump is connected with a feed hole of a slurrying tank in a step-by-step temperature and pressure raising unit, and a discharge hole of a hydrolysis tank in the step-by-step temperature and pressure raising unit is connected with a feed hole of a multi-stage flash evaporation unit; the step-by-step heating and boosting unit comprises a slurrying tank, a preheating tank and a hydrolysis tank which are connected in sequence; the multistage flash unit comprises a plurality of flash tanks which are connected in sequence; the hydrolysis tank is also connected with a steam boiler; the discharge port of the multistage flash evaporation unit is connected with the feed port of the heat exchanger, the discharge port of the heat exchanger is connected with the feed port of the automatic filter-pressing system, and the discharge port of the automatic filter-pressing system outputs dewatered mud cakes. The process can enable the water content of the subsequent dewatered mud cake to reach 50%, and compared with the water content of the subsequent dewatered mud cake in the prior art which is 60%, the water content of the subsequent dewatered mud cake is reduced by 10%.
Description
Technical Field
The invention belongs to the field of sewage treatment, relates to sludge pretreatment, and particularly relates to a continuous sludge pyrohydrolysis system and a continuous sludge pyrohydrolysis process capable of efficiently and fully pyrohydrolyzing.
Background
The sludge pyrohydrolysis is a sludge pretreatment mode, and the principle of the sludge pyrohydrolysis is that microbial flocs in sludge are decomposed, cells are broken, organic matters are hydrolyzed by heating and pressurizing in a pressure container, the binding effect of solid particles of viscous sludge on water is reduced, the water distribution characteristic of the sludge is fundamentally changed, intracellular water, capillary adsorption water and surface adsorption water are separated out in a large amount, more water in the sludge meets the mechanical dehydration requirement, and the dehydration performance of the sludge is improved. Meanwhile, macromolecular organic matters in the cells are released and hydrolyzed into micromolecular substances, and the micromolecular substances are transferred from the solid phase to the liquid phase, so that the anaerobic digestion performance of the sludge is improved. Finally, stabilization, reduction, harmlessness and energy regeneration of the sludge are realized.
Sludge is a product after sewage treatment, and is an extremely complex heterogeneous body consisting of organic debris, bacterial cells, inorganic particles, colloids and the like. In order to ensure the efficient operation of subsequent treatment systems such as anaerobic digestion and drying of sludge and realize the stabilization and harmlessness of sludge, a reasonable pretreatment technology is imperative.
The sludge pyrohydrolysis technology is one of the main pretreatment technologies for anaerobic digestion of sludge, can destroy the colloid structure and the capillary structure of the sludge, break sludge cells, release the combined water in the cells and the water adsorbed on the surfaces of the cells into free water, improve the fluid performance of the sludge, facilitate the conveying and greatly improve the settling performance and the dehydration performance of the sludge; organic matters in cells are released, macromolecular organic matters are further hydrolyzed into micromolecular substances, the organic matters are favorably transferred from a solid phase to a liquid phase, the ratio of the solid-phase organic matters is reduced, the solid-phase substances are favorably stabilized and finally treated, and favorable conditions are provided for the subsequent degradation and dehydration treatment of sludge organic matters. Has been widely applied in practical engineering.
The sludge thermal hydrolysis device is divided into a continuous batch type sludge thermal hydrolysis device and a continuous batch type sludge thermal hydrolysis device in the operation mode, and the continuous batch type sludge thermal hydrolysis device is the most widely applied sludge thermal hydrolysis device at present. The continuous batch sludge pyrohydrolysis process generally comprises the following steps: a certain amount of sludge is put into a thermal hydrolysis tank and is kept for a certain time under high temperature and high pressure, so that the sludge is discharged after the thermal hydrolysis of the sludge is finished, and the sludge is conveyed to the next treatment link. The method has the advantages of complex operation, high energy consumption, low treatment efficiency and higher investment and operation cost, and is not beneficial to the large-scale application of the sludge pyrohydrolysis process.
The prior art discloses an anti-clogging sludge continuous thermal hydrolysis system, which ensures that only clean fluid flows through the shell side of a heat exchanger by coupling a partial oxidation technology and an intermediate medium regenerative thermal hydrolysis system, and avoids frequent change of sludge conveying direction. Carry out broken grinding to feeding mud through the grinding pump, prevent that the mud granule reunion from hardening, adopt multistage gradient to utilize system's heat simultaneously to adopt the biochemical marsh gas technique of producing of anaerobism, carry out resource utilization to mud pressure filtrating, return flow technology anterior segment carries out the viscosity reduction to mud behind the heat transfer of partial mud pressure filtrating simultaneously, avoids using fresh demineralized water, when improving the hot retrieval and utilization efficiency of system, has reduced system resource consumption, effectively promotes system's economic nature. The system can realize continuous thermal hydrolysis of the sludge. However, this system has two drawbacks: firstly, the sludge pyrohydrolysis flow is short, and the pyrohydrolysis is insufficient; and secondly, energy sources such as steam and the like are not fully recycled, so that the cost of sludge pyrohydrolysis is increased.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a continuous sludge pyrohydrolysis system and a continuous sludge pyrohydrolysis process capable of efficiently and fully pyrohydrolyzing, and solve the technical problems that in the prior art, the sludge pyrohydrolysis treatment efficiency is low, and the pyrohydrolysis is insufficient, so that the water content of the final dewatered sludge cake is high.
In order to solve the technical problems, the invention adopts the following technical scheme:
a continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing comprises a sludge bin, wherein a discharge hole of the sludge bin is connected with a grinding pump, the grinding pump is connected with a feed hole of a slurrying tank in a step-by-step temperature and pressure raising unit, and a discharge hole of a hydrolysis tank in the step-by-step temperature and pressure raising unit is connected with a feed hole of a multi-stage flash evaporation unit;
the step-by-step heating and boosting unit comprises a slurrying tank, a preheating tank and a hydrolysis tank which are connected in sequence;
the multistage flash unit comprises a plurality of flash tanks which are connected in sequence;
the hydrolysis tank is also connected with a steam boiler;
the discharge port of the multistage flash evaporation unit is connected with the feed port of the heat exchanger, the discharge port of the heat exchanger is connected with the feed port of the automatic filter-pressing system, and the discharge port of the automatic filter-pressing system outputs dewatered mud cakes.
The invention also has the following technical characteristics:
the liquid outlet of the automatic filter-pressing system is connected with a sludge pressure filtrate collecting tank, and the sludge pressure filtrate collecting tank is connected with a sludge pressure filtrate inlet of the heat exchanger through a centrifugal pump and is used for partially recovering sludge pressure filtrate.
Multistage flash distillation unit including consecutive one flash tank, two flash tanks and three flash tanks, the discharge gate of hydrolysis tank links to each other with the feed inlet of one flash tank, the discharge gate of three flash tanks links to each other with the feed inlet of heat exchanger.
A sludge press filtrate liquid outlet of the heat exchanger is connected with a three-flash heat exchanger arranged in a three-flash tank, and the three-flash heat exchanger is communicated with a sludge bin through a three-flash heat exchange tube; the secondary flash evaporation tank is communicated with the slurrying tank through a secondary flash evaporation steam recovery pipe; the flash tank is communicated with the preheating tank through a flash steam recovery pipe.
A first screw pump is arranged between the sludge bin and the grinding pump; a second screw pump is arranged between the slurrying tank and the preheating tank; and a third screw pump is arranged between the preheating tank and the hydrolysis tank.
The invention also discloses a continuous sludge pyrohydrolysis process capable of efficiently and fully pyrohydrolyzing, which adopts the continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing;
in the step-by-step heating and boosting unit, the temperature in the slurrying tank is increased to 85-90 ℃, and the pressure is normal pressure; the temperature in the preheating tank is increased to 120-130 ℃, and the pressure is increased to 0.2 MPa; the temperature in the hydrolysis tank is raised to 180 ℃ and the pressure is 1.0 MPa.
In the step-by-step heating and pressure boosting unit, the residence time of sludge in the slurrying tank, the preheating tank and the hydrolysis tank is 40 min.
The water content of the sludge in the sludge bin is improved to 83 percent from 80 percent, the water content of the sludge in the slurrying tank is improved to 85 percent from 83 percent, the water content of the sludge in the preheating tank is improved to 86 percent from 85 percent, and the water content of the sludge in the hydrolysis tank is improved to 87 percent from 86 percent.
When the continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing works stably, the temperature and the water content of sludge in the sludge bin are completely regulated and controlled by sludge press filtrate recovered from the triple-flash heat exchange tube after being heated by the heat exchanger and the triple-flash heat exchanger; the temperature and the water content of the sludge in the slurrying tank are completely regulated and controlled by the steam recovered from the two-flash steam recovery pipe; the temperature, pressure and water content of the sludge in the preheating tank are completely regulated and controlled by the steam recovered from a flash steam recovery pipe.
Specifically, the method takes sludge with the water content of 80% as a pyrohydrolysis object, and comprises the following steps in terms of the treatment capacity of 2.5 tons/day:
firstly, discharging sludge with water content of 80% generated by sewage treatment into a sludge bin; starting the centrifugal pump, and simultaneously starting the first screw pump, the second screw pump, the third screw pump and the grinding pump;
step two, heating part of sludge press filtrate by a heat exchanger and a triple flash heat exchanger in a triple flash tank by a centrifugal pump, inputting the heated sludge press filtrate into a sludge bin through a triple flash heat exchange tube, increasing the water content of the sludge in the sludge bin from 80% to 83%, increasing the temperature to 30 ℃, and pumping the sludge into a grinding pump by a first screw pump to realize homogenization of the sludge;
step three, the homogenized sludge enters a slurrying tank, steam in a secondary flash evaporation tank is input into the slurrying tank through a secondary flash evaporation steam recovery pipe, the water content of the sludge in the slurrying tank is increased from 83% to 85%, the temperature is increased to 85-90 ℃, the sludge is stirred under normal pressure, and the sludge stays for 40 minutes;
pumping the sludge into a preheating tank from the slurrying tank through a second screw pump, inputting steam in a flash tank into the preheating tank through a flash steam recovery pipe, increasing the water content of the sludge in the preheating tank from 85% to 86%, increasing the temperature to 120-130 ℃, increasing the pressure to 0.2MPa, stirring the stirring slurry, and staying for 40 minutes;
pumping the sludge from the preheating tank into a hydrolysis tank through a third screw pump, inputting high-temperature and high-pressure steam into the hydrolysis tank through a steam boiler, increasing the water content of the sludge from 86% to 87%, increasing the temperature to 180 ℃, and keeping the sludge at the pressure of 1.0MPa for stirring by a stirring paddle for 40 minutes;
and step six, the sludge subjected to thermal hydrolysis sequentially enters a first flash evaporation tank, a second flash evaporation tank and a third flash evaporation tank from a hydrolysis tank to realize multi-stage flash evaporation, then is input into a heat exchanger, is input into an automatic filter pressing system after being subjected to heat exchange and temperature reduction through the heat exchanger, and is subjected to filter pressing through the automatic filter pressing system to generate a dewatered sludge cake and sludge press filtrate, the dewatered sludge cake is transported outwards, the sludge press filtrate enters a sludge press filtrate collection tank, part of the sludge press filtrate is pumped into a sludge storage bin through the heat exchanger and the third flash heat exchanger in the third flash evaporation tank through a centrifugal pump, and the rest sludge press filtrate is discharged to a sewage treatment plant for treatment.
Compared with the prior art, the invention has the following technical effects:
according to the invention, (I) the pyrohydrolysis process combining the gradual heating and boosting of the sludge and the multistage flash evaporation is adopted, the gradual heating and boosting unit and the multistage flash evaporation unit have a synergistic effect, the degree of pyrohydrolysis of the sludge can be more thorough due to the gradual heating and boosting, and the multistage flash evaporation can fully separate out water in the sludge from the sludge on the basis of more full pyrohydrolysis of the sludge in the hydrolysis tank, so that the water content in the final dewatered sludge cake is reduced. The two are cooperated, so that the thermal hydrolysis degree of the sludge is fully improved, and convenience is provided for subsequent treatment.
(II) through experimental simulation verification, the process can enable the water content of the subsequent dewatered mud cake to reach 50%, and compared with the water content of the subsequent dewatered mud cake in the prior art which is 60%, the water content of the subsequent dewatered mud cake is reduced by 10%.
According to the invention, (III) through energy recovery of the first, second and third flash tanks and the heat exchanger, the energy is recycled fully in a gradient manner, and the operation cost is greatly reduced. The experiment simulation proves that the process can reduce the consumption of raw material steam by 20 percent, and compared with the process in the prior art, the cost is reduced by at least 30 percent.
(IV) the continuous sludge pyrohydrolysis method has the advantages of continuous sludge feeding and discharging, high braking degree and good stability, improves the sludge treatment efficiency, reduces the operation cost, and provides a reliable new way for large-scale engineering application of the sludge pyrohydrolysis technology.
Drawings
FIG. 1 is a schematic structural diagram of a continuous sludge pyrohydrolysis system capable of efficient and sufficient pyrohydrolysis.
The meaning of the individual reference symbols in the figures is: 1-a sludge bin, 2-a grinding pump, 3-a step-by-step heating and boosting unit, 4-a multi-stage flash evaporation unit, 5-a steam boiler, 6-a heat exchanger, 7-an automatic filter pressing system, 8-a sludge pressure filtrate collecting tank, 9-a centrifugal pump, 10-a three-flash heat exchanger, 11-a three-flash heat exchange tube, 12-a two-flash evaporation steam recovery tube, 13-a one-flash evaporation steam recovery tube, 14-a first screw pump, 15-a second screw pump and 16-a third screw pump.
301-slurrying tank, 302-preheating tank, 303-hydrolysis tank;
401-one flash tank, 402-two flash tanks, and 403-three flash tanks.
The details of the present invention are explained in further detail below with reference to the drawings and examples.
Detailed Description
It is to be noted that all components in the present invention, unless otherwise specified, are all those known in the art. The automated press filtration system employs a known automated press filtration system commonly used in the art.
The following embodiments of the present invention are provided, and it should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.
Example 1:
the embodiment provides a continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing, and as shown in fig. 1, the system comprises a sludge bin 1, wherein a discharge hole of the sludge bin 1 is connected with a grinding pump 2, the grinding pump 2 is connected with a feed hole of a slurrying tank 301 in a step-by-step temperature and pressure raising unit 3, and a discharge hole of a hydrolysis tank 303 in the step-by-step temperature and pressure raising unit 3 is connected with a feed hole of a multi-stage flash evaporation unit 4;
the gradual heating and pressure boosting unit 3 comprises a slurrying tank 301, a preheating tank 302 and a hydrolysis tank 303 which are connected in sequence;
the multi-stage flash unit 4 comprises a plurality of flash tanks which are connected in sequence;
the hydrolysis tank 303 is also connected with a steam boiler 5;
the discharge port of the multistage flash evaporation unit 4 is connected with the feed port of the heat exchanger 6, the discharge port of the heat exchanger 6 is connected with the feed port of the automatic filter pressing system 7, and the discharge port of the automatic filter pressing system 7 outputs dewatered mud cakes.
As a preferable scheme of this embodiment, a liquid outlet of the automatic pressure filtration system 7 is connected to a sludge pressure filtrate collection tank 8, and the sludge pressure filtrate collection tank 8 is connected to a sludge pressure filtrate liquid inlet of the heat exchanger 6 through a centrifugal pump 9, and is used for partially recovering the sludge pressure filtrate.
As a specific scheme of this embodiment, the multistage flash unit 4 includes a flash tank 401, two flash tanks 402 and three flash tanks 403 that link to each other in proper order, and the discharge gate of the hydrolysis tank 303 links to each other with the feed inlet of a flash tank 401, and the discharge gate of three flash tanks 403 links to each other with the feed inlet of heat exchanger 6.
As a further scheme of the embodiment, a sludge press filtrate outlet of the heat exchanger 6 is connected with a triple flash heat exchanger 10 installed in a triple flash evaporation tank 403, and the triple flash heat exchanger 10 is communicated with a sludge bin 1 through a triple flash heat exchange tube 11; the secondary flash evaporation tank 402 is communicated with the slurrying tank 301 through a secondary flash evaporation steam recovery pipe 12; a flash tank 401 communicates with the preheat tank 302 through a flash vapor recovery line 13.
As a preferable scheme of the embodiment, a first screw pump 14 is arranged between the sludge bin 1 and the grinding pump 2; a second screw pump 15 is arranged between the slurrying tank 301 and the preheating tank 302; a third screw pump 16 is arranged between the preheating tank 302 and the hydrolysis tank 303.
Example 2:
the embodiment provides a continuous sludge pyrohydrolysis process capable of efficiently and sufficiently pyrohydrolyzing, which adopts the continuous sludge pyrohydrolysis system capable of efficiently and sufficiently pyrohydrolyzing provided in embodiment 1;
the process comprises the following steps:
in the step-by-step heating and boosting unit 3, the temperature in the slurrying tank 301 is raised to 85-90 ℃, and the pressure is normal pressure; the temperature in the preheating tank 302 is increased to 120-130 ℃, and the pressure is increased to 0.2 MPa; the temperature in the hydrolysis tank 303 is raised to 180 ℃ and the pressure is 1.0 MPa.
In the gradual heating and pressure boosting unit 3, the residence time of the sludge in the slurrying tank 301, the preheating tank 302 and the hydrolysis tank 303 is 40 min.
The water content of the sludge in the sludge bin 1 is improved to 83 percent from 80 percent, the water content of the sludge in the slurrying tank 301 is improved to 85 percent from 83 percent, the water content of the sludge in the preheating tank 302 is improved to 86 percent from 85 percent, and the water content of the sludge in the hydrolysis tank 303 is improved to 87 percent from 86 percent.
When the continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing works stably, the temperature and the water content of sludge in the sludge bin 1 are completely regulated and controlled by sludge press filtrate recovered from the triple-flash heat exchange tube after being heated by the heat exchanger 6 and the triple-flash heat exchanger 10; the temperature and the water content of the sludge in the slurrying tank 301 are completely controlled by the steam recovered from the double-flash steam recovery pipe 12; the temperature, pressure and moisture content of the sludge in the preheating tank 302 are completely regulated by the steam recovered from a flash steam recovery pipe 13.
Example 3:
the embodiment provides a continuous sludge pyrohydrolysis process capable of efficiently and sufficiently pyrohydrolyzing, which adopts the continuous sludge pyrohydrolysis system capable of efficiently and sufficiently pyrohydrolyzing provided in embodiment 1;
the method takes sludge with the water content of 80 percent as a pyrohydrolysis object, and comprises the following steps by the treatment amount of 2.5 tons/day:
firstly, discharging sludge with water content of 80 percent generated by sewage treatment into a sludge bin 1; starting the centrifugal pump 9, and simultaneously starting the first screw pump 14, the second screw pump 15, the third screw pump 16 and the grinding pump 2;
step two, a centrifugal pump 9 heats part of sludge press filtrate through a heat exchanger 6 and a triple flash heat exchanger 10 in a triple flash evaporation tank 403, and then inputs the heated sludge press filtrate into a sludge bin 1 through a triple flash heat exchange tube 11, the water content of the sludge in the sludge bin 1 is increased from 80% to 83%, the temperature is increased to 30 ℃, and the sludge is pumped into a grinding pump 2 through a first screw pump 14, so that the homogenization of the sludge is realized;
step three, the homogenized sludge enters a slurrying tank 301, steam in a secondary flash evaporation tank 402 is input into the slurrying tank 301 through a secondary flash evaporation steam recovery pipe 12, the water content of the sludge in the slurrying tank 301 is increased from 83% to 85%, the temperature is increased to 85-90 ℃, the stirring slurry is stirred at normal pressure and stays for 40 minutes;
pumping the sludge from the slurrying tank 301 into the preheating tank 302 through a second screw pump 15, inputting steam in a flash tank 401 into the preheating tank 302 through a flash steam recycling pipe 13, increasing the water content of the sludge in the preheating tank 302 from 85% to 86%, increasing the temperature to 120-130 ℃, increasing the pressure to 0.2MPa, stirring the stirring slurry, and staying for 40 minutes;
step five, pumping the sludge from the preheating tank 302 into the hydrolysis tank 303 through a third screw pump 16, inputting high-temperature and high-pressure steam into the hydrolysis tank 303 through a steam boiler 5, increasing the water content of the sludge from 86% to 87%, increasing the temperature to 180 ℃, and keeping the pressure at 1.0MPa, stirring by using a stirring paddle, and keeping for 40 minutes;
step six, the sludge after thermal hydrolysis sequentially enters a first flash evaporation tank 401, a second flash evaporation tank 402 and a third flash evaporation tank 403 from a hydrolysis tank 303 to realize multi-stage flash evaporation, then is input into a heat exchanger 6, is input into an automatic filter pressing system 7 after heat exchange and temperature reduction through the heat exchanger 6, generates a dewatered mud cake and sludge press filtrate after filter pressing through the automatic filter pressing system 7, the dewatered mud cake is transported outwards, the sludge press filtrate enters a sludge press filtrate collecting tank 8, part of the sludge press filtrate is pumped into a sludge storage bin 1 through a centrifugal pump 9 through the heat exchanger 6 and a third flash heat exchanger 10 in the third flash evaporation tank 403, and the rest sludge press filtrate is discharged to a sewage treatment plant for treatment.
Specifically, in the multistage flash process, the temperature in the first flash tank 401 is 148 ℃, the pressure is 0.45MPa, the temperature in the second flash tank 402 is 110 ℃, the pressure is 0.14MPa, the temperature in the third flash tank 403 is 70 ℃, and the pressure is normal pressure.
Through experimental simulation verification, the process of the embodiment can enable the water content of the subsequent dewatered mud cake to reach 50%, and compared with the water content of the subsequent dewatered mud cake in the prior art of 60%, the water content of the subsequent dewatered mud cake is reduced by 10%. The process of the present example can reduce the raw steam consumption by 20%, and the cost is reduced by at least 30% compared with the prior art process.
Comparative example 1:
the comparative example shows a continuous sludge pyrohydrolysis process, and the difference between the continuous sludge pyrohydrolysis system adopted by the process and the continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing provided in the example 1 is only that the system of the comparative example does not have the multi-stage flash evaporation unit 4, only has the step-by-step temperature and pressure raising unit 3, and the discharge hole of the hydrolysis tank 303 in the step-by-step temperature and pressure raising unit 3 is directly connected with the feed hole of the heat exchanger 6.
Specifically, the continuous sludge pyrohydrolysis system that this comparative example adopted, this system includes mud feed bin 1, and the discharge gate of mud feed bin 1 links to each other with grinding pump 2, and grinding pump 2 links to each other with the feed inlet of pulp jar 301 that rises in the pressure unit 3 step by step, and the discharge gate of pulp jar 301 links to each other with the feed inlet of heat exchanger 6, and the discharge gate of heat exchanger 6 links to each other with the feed inlet of automatic filter pressing system 7, and the discharge gate of automatic filter pressing system 7 outputs the dewatered mud cake.
The gradual heating and pressure boosting unit 3 comprises a slurrying tank 301, a preheating tank 302 and a hydrolysis tank 303 which are connected in sequence;
the hydrolysis tank 303 is also connected with a steam boiler 5;
a first screw pump 14 is arranged between the sludge bin 1 and the grinding pump 2; a second screw pump 15 is arranged between the slurrying tank 301 and the preheating tank 302; a third screw pump 16 is arranged between the preheating tank 302 and the hydrolysis tank 303.
The method of the comparative example is carried out according to the following steps by taking sludge with 80 percent of water content as a pyrohydrolysis object and taking the treatment amount of 2.5 tons/day:
firstly, discharging sludge with water content of 80 percent generated by sewage treatment into a sludge bin 1; starting the first screw pump 14, the second screw pump 15, the third screw pump 16 and the grinding pump 2;
step two, increasing the water content of the sludge in the sludge bin 1 from 80% to 83%, increasing the temperature to 30 ℃, and pumping the sludge into the grinding pump 2 through the first screw pump 14 to realize homogenization of the sludge;
step three, increasing the water content of the sludge in the slurrying tank 301 from 83% to 85%, increasing the temperature to 85-90 ℃, stirring with a stirring paddle under normal pressure, and staying for 40 minutes;
pumping the sludge from the slurrying tank 301 into the preheating tank 302 through a second screw pump 15, increasing the water content of the sludge in the preheating tank 302 from 85% to 86%, increasing the temperature to 120-130 ℃, increasing the pressure to 0.2MPa, stirring the stirring slurry, and staying for 40 minutes;
step five, pumping the sludge from the preheating tank 302 into the hydrolysis tank 303 through a third screw pump 16, inputting high-temperature and high-pressure steam into the hydrolysis tank 303 through a steam boiler 5, increasing the water content of the sludge from 86% to 87%, increasing the temperature to 180 ℃, and keeping the pressure at 1.0MPa, stirring by using a stirring paddle, and keeping for 40 minutes;
and step six, directly inputting the sludge subjected to thermal hydrolysis into a heat exchanger 6 through a hydrolysis tank 303, inputting the sludge into an automatic filter pressing system 7 after heat exchange and temperature reduction through the heat exchanger 6, and performing filter pressing through the automatic filter pressing system 7 to generate a dewatered sludge cake and sludge press filtrate, wherein the dewatered sludge cake is transported outwards, and the sludge press filtrate is discharged to a sewage treatment plant for treatment.
The experimental simulation verifies that the process of the comparative example can ensure that the water content of the subsequent dewatered mud cake reaches 54 percent, and compared with the water content of the subsequent dewatered mud cake of 60 percent in the prior art, the process of the invention only reduces the water content of the subsequent dewatered mud cake by 6 percent.
From the comparison between example 3 and comparative example 1, it can be seen that the water content of the dewatered cake is reduced to some extent without the multi-stage flash unit 4, but the hydrolysis degree is still not ideal, so that the cooperation between the step-by-step temperature-rise pressure-rise unit 3 and the multi-stage flash unit 4 is only achieved under the condition that the step-by-step temperature-rise pressure-rise unit 3 and the multi-stage flash unit 4 are combined, and the water content of the final dewatered cake is reduced. Furthermore, without the multi-stage flash unit 4, energy cannot be recovered, raw material steam consumption is large, and cost is high.
Claims (10)
1. A continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing comprises a sludge bin (1), wherein a discharge hole of the sludge bin (1) is connected with a grinding pump (2), and is characterized in that the grinding pump (2) is connected with a feed inlet of a slurrying tank (301) in a step-by-step heating and boosting unit (3), and a discharge hole of a hydrolysis tank (303) in the step-by-step heating and boosting unit (3) is connected with a feed inlet of a multi-stage flash evaporation unit (4);
the step-by-step heating and boosting unit (3) comprises a slurrying tank (301), a preheating tank (302) and a hydrolysis tank (303) which are connected in sequence;
the multistage flash unit (4) comprises a plurality of flash tanks which are connected in sequence;
the hydrolysis tank (303) is also connected with a steam boiler (5);
the discharge port of the multistage flash evaporation unit (4) is connected with the feed port of the heat exchanger (6), the discharge port of the heat exchanger (6) is connected with the feed port of the automatic filter pressing system (7), and the discharge port of the automatic filter pressing system (7) outputs dewatered mud cakes.
2. The continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing according to claim 1, wherein the liquid outlet of the automatic filter-pressing system (7) is connected to a sludge press-filtrate collection tank (8), and the sludge press-filtrate collection tank (8) is connected to the sludge press-filtrate inlet of the heat exchanger (6) through a centrifugal pump (9) for partially recovering the sludge press-filtrate.
3. The continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing according to claim 2, wherein the multistage flash unit (4) comprises a flash tank (401), a flash tank (402) and a flash tank (403) which are connected in sequence, the discharge port of the hydrolysis tank (303) is connected with the feed port of the flash tank (401), and the discharge port of the flash tank (403) is connected with the feed port of the heat exchanger (6).
4. The continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing according to claim 3, wherein the sludge press filtrate outlet of the heat exchanger (6) is connected with a triple flash heat exchanger (10) arranged in a triple flash evaporation tank (403), and the triple flash heat exchanger (10) is communicated with the sludge bin (1) through a triple flash heat exchange tube (11); the secondary flash evaporation tank (402) is communicated with the slurrying tank (301) through a secondary flash evaporation recovery pipe (12); the flash tank (401) is communicated with the preheating tank (302) through a flash steam recovery pipe (13).
5. The continuous sludge pyrohydrolysis system capable of realizing efficient and sufficient pyrohydrolysis according to claim 4, wherein a first screw pump (14) is arranged between the sludge bin (1) and the grinding pump (2); a second screw pump (15) is arranged between the slurrying tank (301) and the preheating tank (302); and a third screw pump (16) is arranged between the preheating tank (302) and the hydrolysis tank (303).
6. A continuous sludge pyrohydrolysis process capable of efficient and sufficient pyrohydrolysis, which is characterized by adopting the continuous sludge pyrohydrolysis system capable of efficient and sufficient pyrohydrolysis according to any one of claims 1 to 5;
in the step-by-step temperature and pressure increasing unit (3), the temperature in the slurrying tank (301) is increased to 85-90 ℃, and the pressure is normal pressure; the temperature in the preheating tank (302) is increased to 120-130 ℃, and the pressure is increased to 0.2 MPa; the temperature in the hydrolysis tank (303) is raised to 180 ℃ and the pressure is 1.0 MPa.
7. The continuous sludge pyrohydrolysis process with high efficiency and sufficient pyrohydrolysis according to claim 6, wherein the residence time of the sludge in the slurry tank (301), the preheating tank (302) and the hydrolysis tank (303) in the temperature and pressure increasing unit (3) is 40 min.
8. The continuous sludge pyrohydrolysis process capable of efficiently and fully pyrohydrolyzing according to claim 6, wherein the water content of the sludge in the sludge bin (1) is increased from 80% to 83%, the water content of the sludge in the slurrying tank (301) is increased from 83% to 85%, the water content of the sludge in the preheating tank (302) is increased from 85% to 86%, and the water content of the sludge in the hydrolysis tank (303) is increased from 86% to 87%.
9. A continuous sludge pyrohydrolysis process capable of efficient and sufficient pyrohydrolysis, which is characterized by adopting the continuous sludge pyrohydrolysis system capable of efficient and sufficient pyrohydrolysis according to claim 4;
when the continuous sludge pyrohydrolysis system capable of efficiently and fully pyrohydrolyzing works stably, the temperature and the water content of sludge in the sludge bin (1) are completely regulated and controlled by sludge press filtrate recovered from the triple-flash heat exchange tube after being heated by the heat exchanger (6) and the triple-flash heat exchanger (10); the temperature and the water content of the sludge in the slurrying tank (301) are completely regulated and controlled by the steam recovered from the double-flash steam recovery pipe (12); the temperature, pressure and water content of the sludge in the preheating tank (302) are completely regulated and controlled by the steam recovered from a flash steam recovery pipe (13).
10. A continuous sludge pyrohydrolysis process capable of efficient and sufficient pyrohydrolysis, which is characterized by adopting the continuous sludge pyrohydrolysis system capable of efficient and sufficient pyrohydrolysis according to claim 5;
the method takes sludge with the water content of 80 percent as a pyrohydrolysis object, and comprises the following steps by the treatment amount of 2.5 tons/day:
firstly, discharging sludge with water content of 80% generated by sewage treatment into a sludge bin (1); starting the centrifugal pump (9), and simultaneously starting the first screw pump (14), the second screw pump (15), the third screw pump (16) and the grinding pump (2);
step two, heating part of sludge press filtrate by a centrifugal pump (9) through a heat exchanger (6) and a three-flash heat exchanger (10) in a three-flash evaporation tank (403), inputting the heated sludge press filtrate into a sludge bin (1) through a three-flash heat exchange tube (11), increasing the water content of the sludge in the sludge bin (1) from 80% to 83%, increasing the temperature to 30 ℃, and pumping the sludge into a grinding pump (2) through a first screw pump (14) to realize homogenization of the sludge;
step three, the homogenized sludge enters a slurrying tank (301), steam in a secondary flash evaporation tank (402) is input into the slurrying tank (301) through a secondary flash evaporation steam recovery pipe (12), the water content of the sludge in the slurrying tank (301) is increased from 83% to 85%, the temperature is increased to 85-90 ℃, the stirring is carried out under normal pressure, and the stirring is carried out for 40 minutes;
pumping the sludge from the slurrying tank (301) into a preheating tank (302) through a second screw pump (15), inputting steam in a flash tank (401) into the preheating tank (302) through a flash steam recovery pipe (13), increasing the water content of the sludge in the preheating tank (302) from 85% to 86%, increasing the temperature to 120-130 ℃, increasing the pressure to 0.2MPa, stirring the stirring slurry, and staying for 40 minutes;
pumping the sludge from the preheating tank (302) into a hydrolysis tank (303) through a third screw pump (16), inputting high-temperature and high-pressure steam into the hydrolysis tank (303) through a steam boiler (5), increasing the water content of the sludge from 86% to 87%, increasing the temperature to 180 ℃, and keeping the sludge at the pressure of 1.0MPa for 40 minutes, and stirring the sludge with stirring slurry;
step six, the sludge after thermal hydrolysis sequentially enters a flash tank (401), a secondary flash tank (402) and a tertiary flash tank (403) from a hydrolysis tank (303) to realize multi-stage flash, then enters a heat exchanger (6), enters an automatic filter pressing system (7) after heat exchange and temperature reduction of the heat exchanger (6), is subjected to filter pressing by the automatic filter pressing system (7) to generate dewatered sludge cakes and sludge press filtrate, the dewatered sludge cakes are transported outwards, the sludge press filtrate enters a sludge press filtrate collecting tank (8), part of the sludge press filtrate is pumped into a sludge storage bin (1) through a centrifugal pump (9) through a heat exchanger (6) and a tertiary flash heat exchanger (10) in the tertiary flash tank (403), and the rest sludge press filtrate is discharged to a sewage treatment plant for treatment.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624547A (en) * | 2020-12-23 | 2021-04-09 | 江苏省环境科学研究院 | Sludge oxidation treatment system and method |
| CN113087364A (en) * | 2021-04-29 | 2021-07-09 | 同济大学 | Nitrogen neutralization process of sludge pyrohydrolysis and incineration coupled system |
| CN115181582A (en) * | 2022-07-07 | 2022-10-14 | 华北电力大学（保定） | Two-stage hydrothermal liquefaction waste heat utilization system and method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112624547A (en) * | 2020-12-23 | 2021-04-09 | 江苏省环境科学研究院 | Sludge oxidation treatment system and method |
| CN113087364A (en) * | 2021-04-29 | 2021-07-09 | 同济大学 | Nitrogen neutralization process of sludge pyrohydrolysis and incineration coupled system |
| CN113087364B (en) * | 2021-04-29 | 2022-08-09 | 同济大学 | Nitrogen neutralization process of sludge pyrohydrolysis and incineration coupled system |
| CN115181582A (en) * | 2022-07-07 | 2022-10-14 | 华北电力大学（保定） | Two-stage hydrothermal liquefaction waste heat utilization system and method |
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