RU2198141C1 - System of sewage water sludge utilization - Google Patents

Abstract

FIELD: ecological protection of nature from waste water sludges, particularly, sanitary engineering; applicable in utilization of sludges of municipal and production sewage waters. SUBSTANCE: system includes the following units: (a) dewatering unit; (b) drying and combustion unit; (c) unit for removing of ash from exhaust gases; (d) flue gases cleaning unit. System is additionally provided with water-to-water heat exchanger with branch pipes of heated water inlet and outlet installed on circulating alkali circuit. Service water pipeline is connected to heated water inlet branch pipe and heated water outlet branch pipe is connected to flocculant mixer. System is also equipped with automatic process control system, unit 1 of preparation for sludge dewatering installed ahead of unit (a) and including primary settling tanks with at least one pumping station of sediment with drive, suction and pressure pipelines, compactors of excess activated sludge with tank and pumping station of compacted sludge with drive, suction and pressure pipelines, sludge tank. Dewatering process lines are additionally provided with sludge temperature gage. Pressure pipelines of sediment pumping station and pressure pipelines of compacted sludge pumping station are connected with sludge tank. Drives of pumping stations of sediment, compacted excess sludge, sludge metering pumps and flocculants are made in the form of frequency-regulated electric drive by frequency converter-asynchronous motor system including asynchronous electric motors and static frequency converters which together with concentration transducer, temperature gage, sludge flowmeter, temperature pickup of effluent gases and temperature pickup of fluidization are connected with automatic process control system. EFFECT: higher efficiency of use. 3 cl, 1 dwg

Description

 The invention relates to the field of environmental protection of nature from waste water, namely to sanitary equipment, and can find application in the disposal of sludge from urban and industrial wastewater.

 There are several methods and systems for their implementation described in the following applications of the Russian Federation.

 2104970 from 1998.02.20. A method of processing sewage sludge to produce liquid fuel.

The essence of the method lies in the fact that the precipitate, heated to 80-90 ^o With, mixed with heated to 100-160 ^o With oil fuel oil or tar with a value of Reynolds criterion more than 100 for 15-35 minutes. The resulting emulsion suspension is used as a liquid boiler fuel.

 2142098 dated 1999.11.27. Convert sludge from paper mills or similar materials.

 The essence of the method lies in the fact that sludge is introduced into the cyclone furnace together with a second fuel source for burning sludge, using the calorific value of the sludge, and its ash content is converted to slag. Sludge provides only 10-40% of the heat supplied to the furnace.

 2109795 from 1998.04.27. A method of obtaining a liquid sulfur-free organic fuel.

 The essence of the method lies in the fact that a suspension of excess activated sludge, which is a waste after biological treatment of domestic and industrial wastewater, is compacted to a concentration of 25-90 g / l and subjected to alkaline hydrolysis by treatment with sodium hydroxide or its mixture with sodium carbonate in an amount of 10 -50 kg / t, calculated on an absolutely dry substance, the obtained alkaline hydrolyzate is separated from the insoluble part of the precipitate and evaporated (using additional fuel) to a concentration of 75-80 wt. %

 2115697 dated 1998.07.20. A method of obtaining a liquid sulfur-free organic fuel.

 The essence of the method lies in the fact that pre-compacted mixture of suspension of sediment of primary sedimentation tanks, which is a waste of the treatment process of domestic and industrial wastewater, suspension of excess activated sludge, which is a waste after biological treatment of domestic and industrial wastewater. The resulting products are treated with a coagulant, dehydrated to a concentration of 10-30 wt.% And subjected to hydrolysis. The resulting hydrolyzate is separated from the insoluble part of the precipitate and evaporated (using additional fuel) to a concentration of 65-80 wt.% To obtain the target product.

 1573911 dated 1999.08.27. A method of processing sewage sludge from pulp and paper production.

The method includes mechanical sludge dewatering, heat treatment (using additional fuel) of the concentrate in the fluidized bed of the catalyst to form a carbonated product and washing it. In this case, the mechanical dewatering of the precipitate is carried out to a dry matter content of 20-25%, the heat treatment of the concentrate is carried out in a fluidized bed of an aluminum-chromium catalyst organized by a lattice nozzle, and at the exit from the fluidized bed of the catalyst, the carbonated product is cooled to 200-300 ^o C.

 95112218 from 1997.10.10. A method of processing excess activated sludge.

 The method includes pre-compaction, dehydration by filtration, followed by drying and burning of dehydrated sludge. Before the filtering stage, the pre-compacted excess activated sludge is treated with white sludge obtained at the causticization stage of green liquor in the process of sulphate-cellulose production, with stirring and a white slurry: excess activated sludge volume ratio of 1: 5-10.

 2145944 from 2000.02.27. The method of disinfection of sewage sludge.

 The method includes preliminary sludge dewatering, granulation, heat treatment in a fluidized bed, wet cleaning of drying gases from dust and condensation of water vapor.

 All of the above methods and installations are characterized by a common drawback - high operating costs, because for the burning of sludge requires constant incidental combustion of additional fuel.

 The closest analogue to the claimed invention is a method and installation for burning sewage sludge, described in the monograph "Sewage disposal and treatment of St. Petersburg", St. Petersburg: Stroyizdat, 1999, p. 197, 380-389.

A known method of disposal of sewage sludge is that the sludge is subjected to the following processing steps:
- (a) dehydration, which involves measuring the concentration of solids in the sludge, feeding it with screw metering pumps to a centrifuge with its simultaneous heating with the help of associated steam by direct ejection into the pipeline, mechanical dewatering of it in a centrifuge with feeding of the flocculant solution obtained therein by mixing the flocculant with industrial water, measuring the magnitude of the torque on the screw and, depending on it, adjusting the magnitude of regulation - the difference between the rotational speeds of the drum and ESA centrifuge, which is determined depending on the measured value of the torque on the screw and the desired concentration of the dewatered sludge;
- (b) drying and burning, involving the supply of preheated air to the furnace and the dehydrated sludge obtained in stage (a) for mixing with a fluidized bed of sand heated to a temperature of more than 700 ^o C, and, if necessary, an additional supply of fuel in the form of natural gas for adjusting the temperature of the fluidized bed, utilizing part of the heat of the exhaust gases in the air-air heat exchanger to heat the air supplied to the fluidized bed of sand, and in the recovery boiler to produce associated steam;
- (c) removal of ash from the flue gas, providing for the supply of flue gas to the electrostatic precipitator, separation of the ash under the influence of an electric field and its disposal;
- (g) purification of flue gases, providing for their supply to a descending venturi column with continuous contact with a circulating acid solution, subsequent supply to an upward irrigated column with continuous contact with a circulating alkaline solution.

Significant disadvantages of this known method are:
- fluctuations in the parameters of the moisture-giving properties of the sludge that go beyond the limits acceptable for adjusting the moisture content of the cake using a centrifuge reverse drive;
- fluctuations in the ratio of ash and organic parts of the sludge that go beyond the limits necessary to ensure the stability of its combustion processes;
- the unreliability of providing one of the important conditions for conducting the process of utilization of sludge - maintaining a constant load on the centrifuge on dry matter (product of the flow rate on the concentration of dry substances).

A system that implements the specified method contains:
- (a) a dewatering unit comprising at least one dewatering production line comprising a screw slurry metering pump with a drive, a suction pipe on which a concentration sensor is mounted, and a pressure pipe connected to a slurry feed pipe on which the slurry flow meter is mounted and steam ejector with suction pipe, flocculant metering pump with drive, with a suction pipe connected to the solution containers of the flocculant solution, which are connected to the container through the flocculant mixer flocculant flow and a process water pipe, with a pressure line of flocculant solution and a flow meter of flocculant solution, a centrifuge with a drum, auger, a main drive for rotating the drum, a reverse drive for changing the relative speed of rotation of the screw and drum, speed meters of the rotor and screw, and a high-pressure pump, dehydrated sludge with a pressure pipe, while the feed pipe of the sludge and the pressure pipe of the flocculant solution are connected to a centrifuge, and the return drive of the centrifuge completed in the form of a frequency-controlled electric drive according to the scheme "frequency converter - asynchronous motor", including an asynchronous electric motor and a static frequency converter;
- (b) a drying and incineration unit comprising at least one drying and incineration process line comprising a furnace with a blast chamber, a dome, a flue gas line, a combustion chamber, at least one sludge injector, at least one additional fuel injector in in the form of natural gas, a fluidization temperature sensor installed in the combustion chamber, a flue gas temperature sensor installed on the flue gas line, a fluidization supercharger with suction and pressure lines, installed in series air-air heat exchanger with nozzles for supplying and discharging heated air and evaporation bags connected to a recovery boiler connected to a steam collector, while the exhaust gas line is connected to air-air heat exchanger with nozzles for supplying and discharging heated air, the blast chamber of the furnace is connected to branch pipe, and the discharge line of the fluidization blower is connected to the pipe for supplying heated air to the air-air heat exchanger, the steam collector of the recovery boiler is connected to the suction a steam nozzle for a steam ejector;
- (c) a unit for removing ash from the exhaust gases, comprising at least one production line for removing ash from the exhaust gases, comprising an electrostatic precipitator with an inlet and outlet gas line, an ash collection and removal system, wherein the inlet gas line is connected to vaporization bags;
- (d) a flue gas purification unit, comprising at least one flue gas purification processing line, comprising a sequentially installed air-air cooler with a supply and exhaust pipe of heated air, a downstream venturi column with a circulating acid circuit and an ascending irrigated column with a circulating alkaline circuit , exhaust fan with suction and pressure lines, while the exhaust line of the exhaust fan is connected to the outlet pipe of the heated air, the ascending irrigated column is connected to the leading branch pipe of an air-air cooler.

Significant disadvantages of the system that implements this method are:
1. Low stability of the technological process of disposal of sludge due to the fact that:
- a screw-type sludge metering pump with a fixed rotation speed of its drive ensures that only the hydraulic load on the centrifuge is constant, but cannot provide a constant load on dry matter;
- the operational reliability of the sludge concentration sensor is very low, the reliability of its readings is not high;
- the centrifuge reverse drive does not provide the necessary stability of the cake moisture with large fluctuations in the moisture-releasing properties of the sludge entering the dehydration.

2. High operating and capital costs in the preparation of a flocculant solution due to the fact that:
- there is no heating system for water-solvent;
- screw-type sludge dispensers, sludge concentration sensors have a small mean time between failures.

 The aim of the invention is to increase the stability of the process, reducing operating and capital costs during disposal of sludge.

 The first objective of the invention is the development of a known method of disposal of sewage sludge by searching for new operations and optimal modes of operations known therein while at the same time finding ways to reduce costs and increase its environmental cleanliness, reliability.

 The second objective of the invention is the creation of a system that implements the proposed method of disposal of sewage sludge while reducing the cost of its creation and with the maximum use of traditional equipment.

The first problem is solved so that in the known method, comprising the following processing steps:
- (a) dehydration, which involves measuring the concentration of solids in the sludge, feeding it with metering pumps to a centrifuge with its simultaneous heating with the help of steam by direct ejection into the pipeline, mechanical dewatering of the sludge in a centrifuge with the supply of a flocculant solution obtained by mixing the flocculant with industrial water, measuring the magnitude of the torque on the screw and, depending on it, adjusting the magnitude of regulation - the difference between the rotational speeds of the drum and the price auger rifugi, which is determined depending on the measured value of the torque on the screw and the desired concentration of the dewatered sludge;
- (b) drying and burning, providing for the supply of preheated air to the furnace and the dehydrated sludge obtained in stage (a) for mixing with a fluidized bed of sand heated to a temperature of more than 700 ^o C, and, if necessary, an additional supply of fuel in the form of natural gas for adjusting the temperature of the fluidized bed, utilizing part of the heat of the exhaust gases in the air-air heat exchanger to heat the air supplied to the fluidized bed of sand, and in the recovery boiler to produce associated steam;
- (c) removal of ash from the flue gases, providing for the supply of flue gases to the electrostatic precipitator, separation of the ash under the influence of an electric field and its disposal;
- (d) purification of flue gases, providing for their supply to a descending venturi column with continuous contact with a circulating acid solution, subsequent supply to an upward irrigated column with continuous contact with a circulating alkaline solution,
according to our invention, the following operations are introduced:
1. To stage (a), stage (1) is additionally carried out - preparation for sludge dewatering, which involves the separation of sludge in the primary sumps, the production of compacted excess sludge in sludge compactors, the supply of sludge and compacted excess sludge by pumping units to the sludge tank, and the supply of prepared sludge using dosing pumps to stage (a), while the average daily performance of the sludge pumping unit P ₁ and the daily average performance of the compacted excess sludge pumping unit P ₂ determine the period dically, at the stages of adjusting the technological process of wastewater treatment from the condition of ensuring the required degree of purification for all or the main controlled ingredients, the dose of flocculants d _flock - from the condition of ensuring the required indicators of sludge dehydration, in the periods between adjustments to the technological process of wastewater treatment the dose of flocculants d _floc indicator k = Q _OS / Q _yi , where Q _OS is the capacity of the sludge pumping unit, Q _yi is the capacity of the compacted excess sludge pumping unit, in continuous This mode is kept constant, in addition, the temperature of the sludge is maintained at an optimum level for the dehydration process by continuously controlling the supply of associated steam to the ejector, at stage (a) the process water is heated before it is mixed with the flocculant, utilizing some of the heat accumulated in the circulating alkaline solution.

2. As the average daily performance of the pumping unit sludge P ₁ and the average daily performance of the pumping unit compacted excess sludge P ₂ , respectively, take the average daily performance of the pumping unit sludge Q $\genfrac{}{}{0ex}{}{\text{day}}{\text{Wed.oc}}$ and average daily productivity of a compacted excess sludge pumping station Q $\genfrac{}{}{0ex}{}{\text{day}}{\text{Wed ui}}$ .
3. The adjustment of the daily average performance of the pumping unit sludge P ₁ and the average daily performance of the pumping unit compacted excess sludge P _{2 is} carried out simultaneously with the dose adjustment of flocculants d _flocs .

4. Between adjustments of the parameters of the sludge support k = Q _OS / Q _yy = P ₁ / P ₂ .

 5. Dosage of sludge is carried out by centrifugal vortex pumps with non-clogged sludge from sewage flowing part, and the level of sludge in the sludge tank is kept constant.

 6. Additionally, the ash content of the sludge is reduced before the sludge is fed into the tank by processing it on hydraulic cyclones.

 This is due to the fact that the proposed method allows to obtain four effects.

 The first effect is that the proposed method allows you to maintain a stable load on the centrifuge on dry matter, regardless of the concentration of sewage sludge at the entrance to the centrifuge, because sludge is dosed using centrifugal vortex pumps with a non-clogged sewage sludge in the flow part, and the sludge level in the sludge tank is kept constant.

The second effect is that the proposed method allows you to maintain fluctuations in the parameters of the moisture-releasing properties of the sludge within the limits acceptable for adjusting the humidity of the cake using a centrifuge reverse drive, since adjusting the average daily performance of the sludge pumping unit P ₁ and the average daily performance of the compacted pumping unit excess sludge P _{2 is} carried out simultaneously with the dose adjustment of flocculants d _flocs , and between adjustments to the parameters of the sludge support k = Q _OS / Q _yy = P ₁ / P ₂ .

и среднесуточную производительность насосной установки уплотненного избыточного ила Q $\genfrac{}{}{0ex}{}{\text{сут}}{\text{ср.уи}}$ устанавливают при корректировке технологического процесса очистки сточных вод из условия обеспечения требуемой степени их очистки, а между корректировками параметров шлама поддерживают k = Q_ос/Q_уи = Р₁/Р₂ постоянным.The third effect is that the proposed method allows you to maintain fluctuations in the ratio of ash and organic parts of the sludge in the range necessary to ensure the stability of the processes of its dehydration and combustion, because average daily sludge pumping capacity

and average daily productivity of a compacted excess sludge pumping station Q $\genfrac{}{}{0ex}{}{\text{day}}{\text{Wed ui}}$ set when adjusting the technological process of wastewater treatment from the conditions of ensuring the required degree of treatment, and between adjustments to the parameters of the sludge keep k = Q _OS / Q _yy = P ₁ / P ₂ constant.

The fourth effect is that the proposed method improves the stability and reliability of the technological process of utilization of sludge while reducing by 2-3 times the operating and capital costs, including the preparation of a flocculant solution, because:
1. Prior to stage (a), stage (1) is additionally carried out, which allows for the initial stabilization of the parameters of the sludge (moisture recovery, the ratio of ash and organic parts) at the stage of preparing it for dehydration.

 2. Additionally, to reduce fuel consumption, the ash content of the sludge is reduced before the sludge is fed into the tank by processing it on hydraulic cyclones.

3. The process water is heated to 20-30 ^° C until it is mixed with the flocculant, utilizing some of the heat that accumulates in the circulating alkaline solution.

The second problem is solved so that in a known system comprising the following blocks:
- (a) dewatering, comprising at least one dewatering production line comprising a sludge metering pump with a drive, a suction pipe on which a concentration sensor is mounted, and a pressure pipe connected to a sludge supply pipe on which a slurry flow meter and a steam ejector are mounted with a suction pipe, a flocculant metering pump with a drive, with a suction pipe connected to the solution tanks of the flocculant solution, which are connected to the flocculant tank through a flocculant mixer This and the technical water pipeline, with the pressure pipe of the flocculant solution and the flow meter of the flocculant solution, a centrifuge with a drum, auger, the main drive for rotating the drum, a reverse drive for changing the relative speed of rotation of the screw and drum, speed meters of the rotor and screw, high-pressure pump for dehydrated sludge with a pressure pipe, while the feed pipe of the sludge and the pressure pipe of the flocculant solution are connected to a centrifuge, and the centrifuge's reverse drive is made in the form of -frequency-controlled drive scheme "frequency converter - induction motor" comprising a motor and an asynchronous static frequency converter;
- (b) drying and burning, including at least one drying and burning process line, comprising a furnace with a blast chamber, a dome, a flue gas line, a combustion chamber, at least one sludge injector, at least one additional fuel injector in the form natural gas, a fluidization temperature sensor installed in the combustion chamber, a flue gas temperature sensor installed on the flue gas line, a fluidization supercharger with suction and pressure lines, sequentially installed in an air-air heat exchanger with heated air inlet and outlet pipes and evaporation bags connected to a recovery boiler connected to a steam collector, while the exhaust gas line is connected to an air-air heat exchanger with heated air inlet and outlet pipes, the blast chamber of the furnace is connected to the pipe the outlet, and the discharge line of the fluidization supercharger is connected to the pipe for supplying heated air to the air-air heat exchanger, the steam collector of the recovery boiler is connected to the suction they steam ejector nozzle;
- (c) removal of ash from the exhaust gases, comprising at least one exhaust gas ash removal process line comprising an electrostatic precipitator with gas inlet and outlet lines, an ash collection and removal system, wherein the gas inlet line is connected to vaporization bags;
- (g) flue gas cleaning, comprising at least one flue gas cleaning production line, comprising sequentially installed air-air cooler with a supply and exhaust pipe of heated air, a downstream venturi column with a circulating acid circuit and an ascending irrigated column with a circulating alkaline circuit, exhaust fan with suction and pressure lines, while the exhaust line of the exhaust fan is connected to the outlet pipe of the heated air, the ascending irrigated column to the bottom yaschim pipe air-air cooler,
according to our invention, the following differences are introduced:
1. The system is additionally equipped with a water-to-water heat exchanger with heated water supply and drain pipes installed on a circulating alkaline circuit, while the process water pipe is connected to the heated water supply pipe and the heated water pipe is connected to the flocculant mixer, the installation is additionally equipped with an automated system process control system (ACS TP), unit (1) - preparation for sludge dehydration, installed in front of unit (a) and including primary sedimentation tanks with at least one sludge pump station with a drive, suction and pressure pipelines, excess activated sludge compactors with a tank and a compacted sludge pump station with a drive, suction and pressure pipelines, sludge reservoir, dewatering lines are additionally equipped with a sludge temperature meter, while pressure piping of the sludge pumping station and pressure pipes of the compacted sludge pumping station are connected to the sludge tank, in addition, sludge pumping station drives, pack bulk excess sludge, sludge metering pumps and flocculants are made in the form of a frequency-controlled electric drive according to the "frequency converter - asynchronous motor" scheme, including asynchronous electric motors and static frequency converters, which together with the concentration sensor, temperature meter, sludge flow meter, outgoing temperature sensor gases, fluidization temperature sensors are connected with industrial control systems.

 2. The sludge metering pump is made in the form of a centrifugal vortex pump with a non-clogged sludge flow part, and a level meter connected to the automatic process control system is installed in the sludge tank.

 3. The system is additionally equipped with a hydraulic cyclone with inlet and outlet pipes, a sludge reservoir, an additional sludge pumping station with suction and pressure pipelines and with a drive in the form of a frequency-controlled electric drive according to the "frequency converter - asynchronous motor" scheme, including an asynchronous electric motor and a static converter frequency, while the suction pipe of the additional sludge pumping station is connected to the sludge tank, and the pressure pipe to the sludge tank, the first branch pipe of the sludge pumping station - with the inlet pipe of the hydraulic cyclone, the outlet pipe - with the sludge tank, in addition, the frequency converters of the electric motors of the additional sludge pump station are connected to the automatic process control system.

 This is due to the fact that the proposed system for implementing the method of disposal of sludge allows you to get four effects.

The first effect is that the proposed method allows you to maintain a stable load on the centrifuge on dry matter, regardless of the concentration of sewage sludge at the entrance to the centrifuge, because:
1) sludge metering pump is made in the form of a centrifugal vortex pump with non-clogged sludge flow part;
2) a level sensor is installed in the sludge tank;
3) drives of sludge pumping stations, sludge additional pumping station, compacted excess sludge, sludge metering pumps are made in the form of frequency-controlled electric drives according to the “frequency converter - asynchronous motor” scheme, including asynchronous electric motors and static frequency converters;
4) the system is supplemented by an automated process control system (ACS TP) associated with a level sensor in the sludge tank, adjustable drives of sludge pumping stations, additional sludge pumping station, compacted excess sludge, sludge metering pumps.

 Together, this allows primary stabilization of the concentration of solids in the sludge, while maintaining a constant level of its rise by metering pumps (from the tank to the centrifuge), to carry out (under these conditions) additional stabilization of the load of dry matter on the centrifuge due to the fact that sludge metering pump is made in the form of a centrifugal vortex pump.

The second effect is that the proposed method allows you to maintain fluctuations in the parameters of the moisture-removing properties of the sludge within the limits acceptable for adjusting the moisture content of the cake using a centrifuge reverse drive, because:
1) the system is supplemented with a preparation unit for sludge dewatering, including primary sedimentation tanks with at least one sludge pump station with a drive, suction and pressure pipes, excess activated sludge compactors with a tank and a compacted sludge pump station with a drive, suction and pressure pipes, sludge tank ;
2) sludge temperature meters are additionally installed on the dewatering technological lines;
3) drives of sludge pumping stations, sludge additional pumping station, compacted excess sludge, sludge metering pumps are made in the form of frequency-controlled electric drives according to the “frequency converter - asynchronous motor” scheme, including asynchronous electric motors and static frequency converters;
4) the system is supplemented by an automated process control system (ACS TP) associated with the controlled drives of sludge pumping stations, an additional sludge pumping station, and compacted excess sludge.

 Together, this allows the preparation of sludge (a mixture of sediment and compacted excess sludge) in an unchanged proportion when changing the volume of its supply, and therefore, stabilize the parameters of the moisture-releasing properties.

 The third effect is that the proposed method allows you to maintain fluctuations in the ratio of ash and organic parts of the sludge within the limits necessary to ensure the stability of the processes of its dehydration and combustion without supplying additional fuel, because the system is supplemented by an automated process control system (ACS TP), a hydraulic cyclone, a sludge reservoir, an additional sludge pumping station.

The fourth effect is that the proposed method improves the stability, reliability and environmental friendliness of the technological process of utilization of sludge while at the same time reducing by 2-3 times the operating and capital costs, including the preparation of a flocculant solution, because:
1) a water-water heat exchanger is installed on the circulating alkaline circuit, in which the process water pipe is connected to the heated water supply pipe and the heated water pipe is connected to the flocculant mixer;
2) drives of sludge pumping stations, additional sludge pumping station, compacted excess sludge, sludge metering pumps and flocculants are made in the form of variable frequency drives according to the “frequency converter - asynchronous motor” scheme, including asynchronous electric motors and static frequency converters.

 Based on the above, we can consider the claimed method of disposal of sewage sludge and the system that implements it, new, because the applicant did not find the mentioned essential features in the patent and scientific and technical information.

 At the same time, certain significant features are known - 1, 3, 9 and 10 of the proposed method and signs 2-5 and 7-9 of the proposed system for its implementation. However, they are used with another set of essential features with which they create the above effects, which is not observed in known similar systems and methods.

 Thus, the claimed method of disposal of sewage sludge and the system that implements it, meet the criterion of "inventive step".

 The practical applicability of the proposed method is illustrated by the example of the operation of the inventive system, illustrated in the drawing.

 The system contains a block (1) for preparing for sludge dehydration, including four primary sumps 1 (the number of sumps is determined by the volume of wastewater entering the treatment plant) with one sludge pumping station 2 with asynchronous electric motors 3 and frequency converters 4 connected to industrial control system 5. Pressure head the pipeline 6 of the sludge pumping station 2 is connected to the inlet pipe 7 of the hydraulic cyclone 8, the outlet pipe 9 of which is connected to the sludge tank 10. The latter is connected to the suction pipe 11 of the additional pump hydrochloric precipitate station 12 with asynchronous motors 13 and inverters 14 connected with ACS 5.

 Four compactors of excess activated sludge 15 (the number of compactors is determined by the volume of wastewater entering the treatment and their treatment mode), connected through a compacted sludge tank 16 to a compacted sludge pumping station 17 with asynchronous electric motors 18 and frequency converters 19, connected with ACS TP 5.

 On the pressure pipelines 20 and 21, respectively, of the compacted sludge pumping station 17 and sludge pumping station 12, condensed sludge flow meters 22 and sludge flow meters 23 are installed respectively. Compacted sludge flow meters 22 and sludge flow meters 23 are connected to the industrial control system 5.

 Pressure pipelines 20 and 21 are connected to a sludge tank 24 equipped with a level gauge 25 connected to an automatic process control system 5. The sludge tank 24 is connected to the same dewatering lines 1 and 2 by means of suction pipes 26. In particular, the suction pipe 26 of technological line 1 which has a concentration sensor 27 connected to the sludge metering pump 28 with an asynchronous electric motor 29 and a frequency converter 30. The concentration sensor 27 and the frequency converter 30 are connected to the industrial control system 5.

 The dewatering line 1 also contains a flocculant metering pump 31 with an asynchronous electric motor 32 and a frequency converter 33 connected to the industrial control system 5. The suction pipe 34 of the flocculant metering pump 31 is connected to the solution tanks of the flocculant solution 35, which are connected to the tank through the flocculant mixer 36 flocculant 37.

 The pressure pipe 38 of the sludge metering pump 28 is connected to the feed pipe of the sludge 39, on which the flow meter 40 is mounted, a steam ejector 41 with a suction pipe 42 and a controlled shut-off body 43, a temperature meter 44. On the pressure pipe of the flocculant solution 45 of the flocculant metering pump 31 a flow meter of a flocculant solution 46 is installed. A controlled shut-off-regulating organ 43, a sludge temperature meter 44, a sludge flow meter 39, a flocculant solution flow meter 46 are connected to the industrial control system 5.

 Sludge supply pipe 39 and flocculant solution pressure pipe 45 of flocculant metering pumps 31 are connected to a centrifuge 47 with a drum 48, a screw 49, a main drive 50, a reverse drive with an asynchronous electric motor 51 and a static frequency converter 52 to change the relative speed of rotation of the screw and drum, a high-pressure pump of dehydrated sludge 53, rotor 54 and screw 55 speed meters. Rotor 54 and screw 55 speed meters are connected to a frequency converter 52, which is connected to the industrial control system 5.

 The pressure pipe 56 of the high-pressure pump of the dehydrated sludge 53 of the dewatering line 1 is connected to the sludge injector 57 of the combustion chamber 58 of the furnace 59, in the lower part of which a blow chamber 60 is installed. The high-pressure pipe of the dehydrated sludge 2 is also connected to the sludge injector 57, i.e. one furnace 59 is fed with slurry from two production lines.

 An additional fuel injector 61 is connected to the combustion chamber 58 and a fluidization temperature sensor 62 is installed. In the dome 63 of the furnace 59, a flue gas temperature sensor 64 is installed, connected to the automated process control system 5. The flue gas line 65 is connected to an air-air heat exchanger 66 with supply pipes 67 and of the outlet 68 of heated air, which is connected to the evaporative bags 69, and the latter with a waste heat boiler 70 with a steam collector 71 connected via a line 72 to the suction pipes 42 of the steam ejectors 41 dewatering technological lines I 1 and 2. The blast chamber of the furnace 60 is connected via a line 73 to the outlet pipe of the heated air 68, and the fluidization blower 74 by the pressure line 75 is connected to the pipe port for the supply of heated air 67 of the air-air heat exchanger 66.

 The vaporization bags 69 are connected via a line 76 to the gas supply line 77 of the electrostatic precipitator 78, containing an ash collection and removal system 79. The exhaust gas line 80 of the electrostatic precipitator 78 is connected to an air-air cooler 81 with a discharge 82 and a supply 83 of heated air pipes. The air-air cooler 81 is connected to a venturi 84 downstream column with an acid circulation circuit 85. A venturi 84 column is connected to an upstream irrigation column 86 with an alkaline circulation circuit 87 on which a water-to-water heat exchanger 88 is installed. To the inlet of the heated water supply 89 to the water-water the heat exchanger 88 is connected to the pipeline of industrial water 90, and the pipe for removing heated water 91 is connected to the flocculant mixer 36 via a pipe 92. The inlet 83 of the heated air duct zdushnogo cooler 81 is connected with a rising reflux column 86 and outlet 82 - with a suction line 93 with the exhauster 94 the pressure line 95.

 The system operates as follows, while realizing the claimed method.

 Wastewater enters four primary sumps 1, from which the sludge is collected by one sludge pumping station 2 with asynchronous electric motors 3 and static frequency converters 4 connected to the industrial control system 5.

 If the ash content of the sludge exceeds the experimentally established value (for each type of sludge it is different), at which it cannot burn without additional fuel, then sludge 2 is pumped through the pressure pipe 6 to the inlet pipe 7 of the hydraulic cyclone 8. In the latter, in the centrifugal field forces is the separation of part of the ash component of the sediment. Through the outlet pipe 9 of the cyclone, the precipitate is fed into the sediment tank 10, from which the suction pipe 11 is taken up by the sediment pumping station 12 with asynchronous electric motors 13 and static frequency converters 14 connected to the industrial control system 5.

 Simultaneously, on four compactors of excess activated sludge 15, it is compacted and gravity flows into the reservoir of compacted sludge 16. From the latter, it is taken away by a compacted sludge pumping station 17 with asynchronous electric motors 18 and static frequency converters 19, connected with ACS TP 5.

 Through pressure pipelines 20 and 21, respectively, compacted sludge and sludge are fed into the sludge tank 24, the level of which is monitored by means of a level gauge 25, connected with ACS TP 5.

At this stage, with the aim of primary stabilization (reduction of fluctuation limits) of the concentration, ash content, moisture-releasing properties of sediments and maintaining a constant level in the sludge tank using ACS TP 5, the operating modes of pumping stations 12 and 17 are regulated as follows. Periodically, the parameters of the wastewater treatment process are adjusted to ensure the required degree of treatment for all or the main controlled ingredients. At the same time, along with other parameters (oxygen concentration, recirculation ratio, etc.), the daily average performance of the sludge pumping unit P ₁ and the daily average performance of the pumping unit of compacted excess sludge P _{2 are} determined.

As the daily average performance P ₁ pumping station sludge 2 can be selected various options:
- work from the condition of providing during the day the specified level of sediment in the primary settlers 1;
- work from the condition of providing during the day the specified humidity of the pumped out sediments;
- work from the conditions of providing during the day the specified pumping volume;
- work from the condition of providing during the day the specified average daily productivity of the sludge pumping unit, etc.

то в данном случае она может быть равна 40 м³/ч. При этом забор осадков может происходить из всех отстойников сразу или по очереди из каждого. В данном случае колебания влажности осадка достигают 5%, а зольности - 6%.In particular, if the average daily productivity of the sludge pumping unit is taken as P ₁

then in this case it can be equal to 40 m ³ / h. In this case, the collection of sediments can occur from all sedimentation tanks immediately or in turn from each. In this case, fluctuations in the moisture content of the sediment reach 5%, and ash content - 6%.

One of their possible average daily performance indicators P ₂ pumped station sludge 17 is to ensure the average daily productivity of the pumping unit compacted excess sludge Q $\genfrac{}{}{0ex}{}{\text{day}}{\text{Wed ui}}$ . In this case, it can be equal to 40 m ³ / h, i.e. The flow of sludge and compacted excess sludge into the sludge tank is the same. In this case, moisture fluctuations in the compacted excess sludge reach 0.5%, and ash content - 4%.

The daily average values of P ₁ and P _{2 are} determined on the basis of the analysis of the balance of substances in the water treatment and precipitation treatment systems. In order to initially stabilize the parameters of the sludge and maintain a constant level in the sludge tank between adjustments, the indicator k = Q _os / Q _yi , where Q _os is the capacity of the sludge pumping unit, Q _yi is the capacity of the compacted excess sludge pumping unit, they are continuously supported constant using ACS PT. Moreover, k = Q _os / Q _yy = P ₁ / P ₂ . In this example, k = Q _os / Q _yy = 40/40 = 1. For example, if the level of sludge in the tank began to increase, then by changing the speed of the drives 18 and 13 of the pumping unit sludge capacity Q _os and the pumping unit capacity of compacted excess sludge Q _{yi are} reduced so that the parameter k remains unchanged, i.e. reduce evenly. This allows the parameters of the sludge, consisting of sludge and compacted excess sludge, to maintain within the permissible range of their fluctuations throughout the entire period between adjustments to the process. For example, fluctuations in the moisture parameters of sludge can be from 0 to 7%, ash content - from 0 to 5%.

 At the second stage of stabilization of the sludge parameters - feeding it to a centrifuge - the system operates in two modes: settings and continuous operation.

In the system setup mode, the sludge from the sludge tank 24 through the suction pipe 26 (for example, the dewatering process line 1) is taken with a vortex dosing pump 28 with a non-clogging flow part and fed to the centrifuge 47 for dehydration. In this case, using a flow meter 40 and ACS TP 5, hydraulic load on the centrifuge 47. By adjusting the speed of the induction motor 29 (using a static frequency converter 30), the sludge metering pump 28 sets the nominal hydraulic manual ultrasonic inspection (by consumption) to centrifuge 47. In this example, it is 40 m ³ / h of sludge. After this continuous adjustment of the speed of the induction motor 29 is not carried out. In addition, experimentally (at the stage of adjusting the parameters of the technological process of wastewater treatment), the optimal performance of the flocculant metering pump 31 is determined (by adjusting the speed of its induction motor 32), at which a dose of flocculants d _flocs is provided, which is prescribed from the condition of ensuring the required dehydration rates sludge. For example, d _flock = 6 kg / t x dry (kilogram of flocculant per ton of solids sludge).

 In the mode of subsequent continuous operation, the dehydration process is regulated by means of a centrifugal-vortex metering pump 28. In this case, for example, if the concentration of dry substances in the sludge increases, the load on the centrifuge 47 on the dry substance does not increase (and, therefore, the plant operation deviates from optimal ) The latter is achieved by the fact that due to the non-clogging of the centrifugal vortex metering pump 28, the constant difference in precipitation levels in the centrifuge 47 and the sludge tank 24, with an increase in the concentration of dry substances in the pumped sludge (increased resistance in the network and the flow part), the centrifugal a vortex metering pump 28 operating at a constant speed of the induction motor 29. In this case, the product of the concentration of solids and the volume of sludge fed to the dewatering Ivan remained virtually unchanged. As a result, the load on the dry matter centrifuge and the dose of flocculants remain unchanged.

 At this stage of stabilization, the spread in the parameters of the sludge is reduced, for example, fluctuations in the load on dry matter are reduced to 1%, ash content - to 4%.

The preparation of the flocculant solution in the solution tanks 35 is carried out with preliminary mixing in the mixer 36 directly the flocculant stored in the tanks 37 and heated water-solvent. The latter is heated to a temperature of 30 ^o With a pressurized water heat exchanger 88. As a result, the duration of dissolution of the flocculant is reduced by 2-3 times.

 At the third stage of stabilization of the parameters of the sludge - dewatering it in a centrifuge - the installation works as follows. The sludge prepared and heated by the steam coming from the steam collector 71 of the waste heat boiler 70 using the ejector 41 is fed to the centrifuge 47. In the latter, the sludge is dehydrated in the field of centrifugal forces generated by the rotation of the drum 48, with the release of the centrate and cake. When the concentration of the cake changes, the torque on the screw changes, which is indirectly determined using the indicators of the rotor 54 and screw 55 speed meters. Depending on the measured value of the torque on the screw and the required concentration of dehydrated sludge, the control value is adjusted — the difference between the drum rotation speeds and auger centrifuge. The latter is carried out using a reverse drive with an induction motor 51 and its static frequency converter 52. In this case, for example, the difference between the rotational speeds of the drum and the centrifuge screw can continuously vary from 2 to 6 rpm.

As a result, dehydrated sludge - cake - with stable properties (for example, with a moisture content of 21%) goes to incineration. For this, 53 high-pressure pumps of dehydrated sludge (2 technological dewatering lines - 1 and 2) are fed to the sludge injectors 57 of the combustion chamber 58 of one furnace 59. The feed from two technological lines, for example, is 1.9 t / h. In the combustion chamber in the fluidized bed of sand due to pre-heated (up to 605 ^o C) in the air-air heat exchanger 66 air fluidization supplied (supply volume - 20,000 m ³ / h) by the blower 74, drying and burning of sludge. In a stable mode, the heat generated is sufficient to maintain combustion. In other cases, the lack of heat is compensated by the supply of additional fuel in the form of natural gas to the combustion chamber through the additional fuel injectors 61. The combustion process is controlled by measuring the fluidization temperature (sensor 62) and the temperature of the exhaust gases (sensor 64). In normal mode, the fluidization temperature is 760 ^o C, and the temperature of the flue gases is 870-880 ^o C.

Utilization of the heat of the exhaust gases is carried out in an air-air heat exchanger 66 and with the help of evaporation bags 69 connected to a waste heat boiler 70 with a steam collector 71. As a result, their temperature is reduced to 250 ^o C.

 Purification of the exhaust gases from the ash is carried out in an electrostatic precipitator 78. The ash is removed from the system through the ash collection and removal system 79.

After removing the ash, before feeding them to the venturi 84 downstream column, the temperature of the flue gases in the air-air cooler 81 is further reduced. The flue gases in the column 84 are irrigated with an acid solution using an acid circulation loop 85, as a result of which their temperature drops to 65 ^o FROM.

Further purification of the flue gases is carried out in an ascending irrigated column 86 with a circulating alkaline circuit 87, on which a water-water heat exchanger 88 is installed. Using the latter, process water is heated from 5 to 30 ^o С to prepare a flocculant solution, which is supplied through a pipe 92 to the flocculant mixer 36.

 Before the supply of purified exhaust gases by means of a smoke exhauster 94 into the chimney, they are directed to an air-air cooler 81.

 Thus, the proposed method and system for its implementation are united by a single inventive concept and, when implemented, can improve the environmental protection of the city from stored sewage sludge.

Claims (3)

 1. A system for the disposal of sewage sludge, comprising the following units: - (a) dewatering, comprising at least one dewatering process line, comprising a sludge metering pump with a drive, a suction pipe on which a concentration sensor is installed, and a pressure pipe connected with a sludge supply pipe, on which a sludge flow meter and a steam ejector with a suction pipe are installed, a flocculant metering pump with a drive, with a suction pipe connected to the solution tanks of the flock yantes, which are connected through a flocculant mixer to a flocculant tank and a process water pipe, to a flocculant solution pressure line and a flocculant solution flow meter, a centrifuge with a drum, a screw, a main drive for rotating the drum, a reverse drive for changing the relative speed of rotation of the screw and drum, speed meters rotor and screw rotations, a high-pressure pump of dehydrated sludge with a pressure pipe, while the feed pipe of the sludge and the pressure pipe of the flocculant solution connected to a centrifuge, and the centrifuge's reverse drive is made in the form of a frequency-controlled electric drive according to the "frequency converter - asynchronous motor" scheme, including an asynchronous electric motor and a static frequency converter; (b) drying and burning, including at least one drying and burning process line, comprising a furnace with a blast chamber, a dome, a flue gas line, a combustion chamber, at least one sludge injector, at least one additional fuel injector in the form of natural gas, a fluidization temperature sensor installed in the combustion chamber, a flue gas temperature sensor installed on the flue gas line, a fluidization supercharger with suction and pressure lines, sequentially installed in air-air heat exchanger with pipes for supplying and discharging heated air and evaporation bags connected to a recovery boiler connected to a steam collector, while the flue gas line is connected to air-air heat exchangers with pipes for supplying and discharging heated air, the blast chamber of the furnace is connected to the pipe outlet, and the discharge line of the fluidization blower is connected to the pipe for supplying heated air to the air-air heat exchanger, the steam collector of the recovery boiler is connected to the suction m steam ejector nozzle; (c) removing ash from the exhaust gases, comprising at least one exhaust gas ash removal process line comprising an electrostatic precipitator with an inlet and outlet gas line, an ash collection and removal system, wherein the inlet gas line is connected to vaporization bags; (d) flue gas purification, including at least one flue gas purification processing line, comprising a sequentially installed air-air cooler with a supply and exhaust pipe of heated air, a descending venturi column with a circulating acid circuit and an ascending irrigated column with a circulating alkaline circuit, a smoke exhauster with suction and pressure lines, while the suction line of the exhaust fan is connected to the outlet pipe of the heated air, the ascending irrigated column is connected to an air-air cooler connecting pipe, characterized in that the system is additionally equipped with a water-to-water heat exchanger with heated water supply and drain pipes installed on a circulating alkaline circuit, while the process water pipe is connected to the heated water supply pipe and the heated water pipe is connected to the flocculant mixer, the installation is additionally equipped with an automated process control system (ACS TP), unit (1) - preparation for sludge dehydration a, installed in front of block (a) and including primary sedimentation tanks with at least one sludge pump station with a drive, suction and pressure pipes, excess activated sludge compactors with a tank and a compressed sludge pump station with a drive, suction and pressure pipes, sludge tank, the dewatering technological lines are additionally equipped with a sludge temperature meter, while the pressure pipes of the sludge pumping station and the pressure pipes of the compacted sludge pumping station are connected with a sludge tank, in addition, sludge pumping station, compacted excess sludge drives, sludge metering pumps and flocculants are made in the form of a frequency-controlled electric drive according to the "frequency converter - asynchronous motor" scheme, including asynchronous electric motors and static frequency converters, which together with a concentration sensor, a temperature meter, a sludge flow meter, a flue gas temperature sensor, a fluidization temperature sensor are connected to the industrial control system.  2. The system for the disposal of sewage sludge according to claim 1, characterized in that the sludge metering pump is made in the form of a centrifugal vortex pump with a non-clogged sludge flow part, and a level meter connected to the industrial control system is installed in the sludge tank.  3. A system for the disposal of sewage sludge according to claims 1 and 2, characterized in that the installation is additionally equipped with a hydraulic cyclone with inlet and outlet pipes, a sludge tank, an additional sludge pumping station with suction and pressure pipes and with a drive in the form of a frequency-controlled electric drive according to the scheme "frequency converter - asynchronous motor", comprising an asynchronous electric motor and a static frequency converter, while the suction pipe of the additional pump station siege it is connected to the sludge tank, and the pressure head to the sludge tank, the pressure head pipe of the sludge pumping station to the inlet pipe of the hydraulic cyclone, the discharge pipe to the sludge tank, in addition, the frequency converters of the electric motors of the additional sludge pumping station are connected to the automatic process control system.