RU2632444C1 - System and method of processing wastewater sludge - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: system comprises a mechanical sludge cleaning device (1), a mechanical thickener (2), a reactor (4) for thermal decomposing liquid sludge, including a tubular body having an inlet for feeding sludge under a pressure of, at least, 25 MPa and an outlet for decomposing products, as well as a heater installed around the body, configured to heat sludge to a temperature of, at least, 450°C, a device for separating the resulting decomposition products into combustible gas and sludge (5), a sludge dehydrating device (6) connected to the outlet of the decomposed sludge of the sludge separating device (5). The outlet of combustible gas of the sludge separating device (5) is connected to the gas generating unit (8) for generating heat and/or electric energy from combustible gas. The gas generating unit (8) is connected to the thickener (2), the reactor (4) and the dehydrating device (6) with the possibility of supplying the generated energy to them. In the system, a method for processing wastewater sludge is carried out.

EFFECT: reducing wastewater sludge by about three times, reducing the ash content, reducing the scale formation in the reactor, increasing the gas component yield and generation efficiency of electric and thermal energy, ensuring the autonomy of the sludge treatment process.

13 cl, 2 dwg

Description

Technical field

The group of inventions relates to the field of water treatment, as well as the field of energy, in particular to the processing of sewage sludge using alternative independent sources of thermal and electric energy.

State of the art

A known complex for the processing of organic waste (see RF patent RU 2408649, December 29, 2008), containing a thermochemical reactor including a recuperative heat exchanger for preheating the pulp and cooling the pyrolysis products and an additional heat exchanger to provide the reactor with a predetermined pyrolytic process temperature. The reactor also includes an ash collector, a light gas separator, a pressure reducing device, and a vapor separator for volatile liquids.

The closest analogue is the system and method for processing sewage sludge disclosed in French application FR 1279568, 12/22/1961. The system includes a sludge thickener, a sludge drying device, a mixer for mixing sludge with carbon or carbide components, a device for briquetting the mixture, a device for gasifying the sludge to produce combustible gas, and a unit (turbine) for generating energy from gas that is used to operate the cleaning devices sewage, as well as drying devices.

The disadvantages of the known devices include:

- a relatively large amount of processed sludge;

- low profitability;

- the formation at the exit of a large amount of solids (ash);

- the possibility of clogging the device for decomposing the precipitate (reactor) with solid substances and the formation of scale.

Disclosure of invention

The objectives of the claimed group of the invention is to eliminate the disadvantages of analogues and to ensure complete disinfection of sludge during autonomous operation of the system without the consumption of electric and thermal energy from external sources.

The technical results of the invention are to reduce the weight of the processed sewage sludge (about three times), reduce ash substances, reduce scale formation in the reactor, increase the gas component yield and the efficiency of electric and thermal energy generation, and ensure the autonomy of the sludge processing process.

These technical results are achieved in the wastewater sludge processing system due to the fact that it contains a device for mechanical treatment of sludge, a mechanical sludge thickener associated with the outlet of the mechanical sludge treatment device, a reactor for thermal decomposition of liquid sludge associated with the outlet of the sludge and including a tubular body, having an input for supplying sludge at a pressure of at least 25 MPa and an outlet for decomposition products, as well as a heater mounted around the housing, made with the possibility of heating sludge to a temperature of at least 450 ° C, a device for separating the obtained decomposition products into combustible gas and decomposed sludge associated with the outlet of the reactor, and a device for dewatering the sludge associated with the outlet of decomposed sludge from the sludge separation device, while the combustible gas outlet of the sludge separation device connected to a gas generator for generating heat and / or electric energy from combustible gas, the gas generator being connected to a thickener, a reactor and a dewatering device the need for supplying them with the generated energy.

In private implementations of the system:

- the system further comprises a sludge dryer associated with the outlet of the dewatering device, as well as with a gas generator with the possibility of supplying energy to the dryer;

- the reactor is connected with the exit of the thickener through a pump with a capacity of 0.1-20 m ³ / h, which ensures the supply of sludge to the reactor, while this pump is connected to a gas generator with the possibility of supplying energy to the pump;

- a sieve with a mesh size of 0.5-2 mm was used as a device for mechanical cleaning.

The indicated technical results are achieved in the method of processing sewage sludge due to the fact that it includes mechanical sludge treatment, mechanical sludge thickening, thermal decomposition of liquid sludge in the reactor at a temperature of at least 450 ° C and a pressure of at least 25 MPa, separation of the obtained decomposition products into combustible gas and decomposed sludge, dehydration of the decomposed sludge, disposal of the resulting sludge, while the processing of combustible gas in a generator set with the generation of heat and / or electricity Coy energy and energy input obtained in the condensation step, the thermochemical decomposition and dehydration.

In private embodiments of the method:

- mechanical cleaning of the precipitate is carried out on a mechanical cleaning device in the form of a sieve with a mesh size of 0.5-2 mm;

- mechanical thickening of the precipitate is carried out to a dry matter content of 8-10 wt. %;

- after thickening, the precipitate is fed into the reactor by means of a pump having a capacity of 0.1-20 m ³ / h;

- dehydration of the decomposed sludge is carried out to a moisture content of 50-70%;

- after dehydration, the sludge is additionally dried to a moisture content of 5-20%;

- for drying use the energy generated by the generator set;

- water separated after thickening the sludge is fed to the sewage treatment plant for treatment;

- sewage treatment plants use the energy generated by the generator set.

Brief Description of the Drawings

The invention is illustrated by drawings, where:

- in FIG. 1 shows a schematic diagram of the claimed system,

- in FIG. 2 shows the basic construction of a reactor for thermal decomposition of siege.

The implementation of the invention

The system according to a preferred embodiment of the invention includes serially installed units: a device for mechanical cleaning (1) of sludge, a mechanical thickener (2) of sludge, a pump (3) for pumping liquid sludge, a reactor (4) for thermal decomposition of liquid sludge, a separation device (5 ) product of decomposition into combustible gas and decomposed sludge, sludge dewatering device (6) and sludge dryer (7) (installed if necessary). Also in the design of the system, a gas generating unit (8) is provided, connected with the exit of combustible gas of the separation device (5).

The device for mechanical cleaning (1) of the precipitate is designed to remove solids (ash) in the form of particles of Ca, Mg, etc. and increasing the organic content of the precipitate. In particular, the device (1) may be a sieve with a mesh size of 0.5-2 mm

Mechanical thickener (2) is designed to increase the solids content and densify the precipitate. The thickener may have various designs that are well known to those skilled in the art. As an example, a thickener in the form of a screw dehydrator of the OSH series manufactured by ECOSPROM can be used.

The pump (3) is designed to pump sediment into the reactor (4) and create a pressure of more than 25 MPa in it. In particular, a pump with a capacity of 0.1-20 m ³ / h can be used.

The reactor (4) serves for the thermal decomposition of a liquid precipitate to produce combustible gas. The reactor (4) (Fig. 2) is a WPR ("Waste Recycling Plant") unit having a horizontal tubular casing (9), at one end of which an inlet (10) is provided for horizontal sludge supply, and also an outlet (11) for vertical disposal of the processed product. A heater (12) is placed around the other end of the reactor vessel, which ensures the creation of a temperature of at least 450 ° C. In this case, the housing (9) and the heater (12) are surrounded by a heat insulator (13).

The separation device (5) is designed to separate the combustible gas from the decomposed sludge. The device (5) may have various designs, widely known to the specialist. In particular, a NIOGAZ-type cyclone can be used.

The dehydration device (6) serves to increase the solids content in the decomposed sludge. The device (6) can be made in the form of a screw dehydrator series "OSH" produced by "ECOSPROM".

A dryer (7) can be used to further remove moisture from the precipitate. As an example, the device can be made in the form of a paddle dryer type "GPD" manufactured by "ROYAL GMF Gouda".

The gas generator unit (8) is designed to generate electric and thermal energy from combustible gas. The device can be made in the form of a cogeneration unit based on gas internal combustion engines.

A method of processing sludge using the described system is implemented as follows.

After passing standard wastewater in sewage treatment plants (WWTP) (14) (the facilities themselves can be part of the claimed system or can be separate units), the resulting liquid sewage sludge with a solid phase concentration of 0.2-3 wt. % together with a pre-added flocculant solution - activated sludge containing phosphorus, is fed to a mechanical cleaning device (1) (sieve), in which large particles larger than 2 mm are retained. The resulting garbage is pressed and disposed of at a solid domestic waste (MSW) landfill (15).

The precipitate passed through a sieve enters the thickener (2), where it thickens to a dry matter concentration of about 8-10 wt. % The separated liquid phase (water) is returned to WWTP (14) for re-purification.

The compacted precipitate obtained is pumped through a pump (3) and fed to a reactor (4) under a pressure of at least 25 MPa (about 30 MPa).

In the reactor, under the influence of a high temperature of at least 450 ° C (about 500 ° C) and a pressure of about 30 MPa, the destruction of complex organic substances of liquid sediment occurs in supercritical water (temperature 374 ° C, pressure 22.1 MPa). Under these conditions, the process proceeds in a short time (several minutes), while the precipitate does not require drying. The specified precipitate decomposes to methane (CH ₄ ), carbon dioxide (CO ₂ ) and ash (inert carbon). The degree of decomposition of ashless sediment is about 90%.

After the reactor, the treated sludge enters the separation device (5), where it is separated into combustible gas (methane) and liquid ash (decomposed sludge).

Liquid ash with a moisture content of 97-98% enters the dehydration device (6). The dewatering device is designed to remove excess moisture from liquid ash up to 70-50% moisture, after which it can be disposed of in solid waste (15) or additionally dried in a drying device (7) to a moisture content of 5-20%. The dried sediment is discharged by a conveyor and taken to a landfill (MSW 15) or reused.

Combustible gas obtained after separation is supplied to a gas generator (8), where it is processed into thermal and electric energy. Thermal energy is sent to the drying device (7), WWTP (4) and the reactor (14). Electric energy is generated in sufficient quantities for the operation of the entire complex of facilities, including WWTP (14), a thickener (2), a pump (3), a dehydration device (6) and a drying device (7).

At the system outlet, a minimum amount of completely disinfected sludge is obtained, which ensures its safe disposal at solid waste landfills, and also significantly reduces transportation costs for sludge removal.

The generated heat and electric energy is sufficient for the autonomous operation of treatment plants and the sludge processing system. Excess energy can be diverted to municipal networks.

Moreover, the ongoing process of gasification of the sediment under supercritical water conditions is promising for the effective conversion of liquid biomass into combustible gas, which can be used as fuel instead of natural gas.

Claims (26)

1. System for the treatment of sewage sludge containing: - a device for mechanical cleaning (1) sludge; - mechanical thickener (2) sludge associated with the output of the mechanical cleaning device (1); - a reactor (4) for the thermal decomposition of liquid sludge associated with the exit of the thickener (2) and including a tubular body (9) having an inlet (10) for supplying sludge under a pressure of at least 25 MPa and an outlet (11) for decomposition products, and a heater (12) also installed around the housing, configured to heat the precipitate to a temperature of at least 450 ° C; - a device for separating (5) the obtained decomposition products into combustible gas and decomposed sediment associated with the outlet of the reactor (4); and - a device for dewatering (6) sludge associated with the release of decomposed sludge separation device (5) sludge; the combustible gas outlet of the separation device (5) of the sludge is connected to a gas generating unit (8) for generating heat and / or electric energy from the combustible gas, and the gas generating unit (8) is connected to a thickener (2), a reactor (4) and a dewatering device (6) with the possibility of supplying them with the generated energy. 2. The system according to claim 1, characterized in that it further comprises a dryer (7) of sludge associated with the outlet of the dewatering device (6), as well as with a gas generator (8) with the possibility of supplying energy to the dryer (7). 3. The system according to claim 1, characterized in that the reactor (4) is connected to the exit of the thickener (2) through a pump (3) with a capacity of 0.1-20 m ³ / h, which ensures the supply of sediment to the reactor (4), while the specified pump (4) is connected with the gas generating unit (8) with the possibility of supplying energy to the pump. 4. The system according to claim 1, characterized in that a sieve with a mesh size of 0.5-2 mm is used as a device for mechanical cleaning (1). 5. A method of processing sewage sludge, including: - mechanical cleaning of sediment, - mechanical thickening of sediment, - thermal decomposition of the liquid precipitate in the reactor (4) at a temperature of at least 450 ° C and a pressure of at least 25 MPa, - separation of the obtained decomposition products into combustible gas and decomposed sediment, - dehydration of the decomposed sludge, - disposal of the resulting sludge, at the same time, combustible gas is processed at the generator set (8) with the generation of thermal and / or electric energy and the supply of the obtained energy to the operations of thickening, thermochemical decomposition and dehydration. 6. The method according to p. 5, characterized in that the mechanical cleaning of the precipitate is carried out on a mechanical cleaning device (1) in the form of a sieve with a mesh size of 0.5-2 mm 7. The method according to p. 5, characterized in that the mechanical thickening of the precipitate is carried out to a dry matter content of 8-10 wt. % 8. The method according to p. 5, characterized in that after thickening the precipitate is fed into the reactor (4) by means of a pump (3) having a capacity of 0.1-20 m ³ / h. 9. The method according to p. 5, characterized in that the dehydration of the decomposed sludge is carried out to a moisture content of 50-70%. 10. The method according to p. 9, characterized in that after dehydration, the sludge is additionally dried to a moisture content of 5-20%. 11. The method according to p. 10, characterized in that for drying use the energy generated by the generator set. 12. The method according to p. 5, characterized in that the water separated after thickening the sludge is fed to the sewage treatment plant (14) for cleaning. 13. The method according to p. 12, characterized in that the sewage treatment plant (14) uses the energy generated by the generator set (8).

Images