CN111088055A

CN111088055A - Self-heating sludge and straw co-carbonization method and device

Info

Publication number: CN111088055A
Application number: CN201911244388.9A
Authority: CN
Inventors: 张书平; 陈民梓; 刘心志; 张后雷; 朱曙光
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2020-05-01

Abstract

The invention discloses a method and a device for co-carbonizing self-heating sludge and straws, and particularly relates to a method and a device for mixing and drying crushed straws and wet sludge in a paddle dryer, and strictly controlling the water content of a mixed biomass material. And (3) the mixed biomass material enters a granulator for granulation treatment, and then the granular biomass material enters a cross-flow bed for pyrolysis to prepare carbon. Pyrolyzing in a cross-flow bed to obtain carbon; in addition, pyrolysis gas collected from the cross flow bed enters a combustion chamber for combustion, high-temperature flue gas is filtered by a calcium oxide filtering device, one part of the high-temperature flue gas circularly enters the cross flow bed to supply heat for pyrolysis, the other part of the high-temperature flue gas enters a heat exchanger, obtained steam returns to a dryer to provide dry heat, and redundant steam heat is collected by a heat reservoir and used for external heat supply. The invention has simple process, fully utilizes the heat of the combusted pyrolysis gas as a heat source for pyrolysis, drying and external heat supply, does not need external heat supply in the whole system, and efficiently and cleanly disposes the sludge and the straws.

Description

Self-heating sludge and straw co-carbonization method and device

Technical Field

The invention relates to the field of sludge and straw treatment, in particular to a method and a device for co-carbonizing self-heating sludge and straws.

Background

On one hand, the sludge is used as a byproduct of urban sewage treatment, the yield is huge, the sludge has high utilization potential, and the sludge pyrolysis technology gradually becomes a research hotspot with good social environment and economic benefits. However, the water content of the dewatered sludge in sewage plants is as high as 80%, and most of pollutants in the original sewage are transferred into the sludge, including various heavy metals, harmful organic matters, pathogens and the like, so that the energy and agricultural utilization of the sludge are seriously hindered. Two problems can occur in the direct pyrolysis of sludge, one is that such high water content can increase very high energy consumption, and the other is that the semi-shaped state of the dewatered sludge requires special feeding equipment.

On the other hand, China is a traditional agricultural big country, and the amount of agricultural straws discarded in China every year is huge, so that the problem of environmental pollution is caused, and the method is a great resource waste. The low energy density of the straw is detrimental to its storage and transportation. In the aspect of straw pyrolysis utilization, because biomass straw moisture content is lower, volatile content is higher, in the straw pyrolysis utilization processing procedure, the straw ash can spill over along with the cigarette, causes the pyrolysis equipment pipeline to block.

The sludge has the characteristics of high water content, high ash content, high viscosity and low heat value. The biomass straws are low in water content, low in ash content and relatively high in heat value, and the straws are added into the sludge, so that the water content of the sludge can be conditioned, the fluidity of the sludge can be increased, continuous feeding is realized, and the quality and efficiency of granulation can be adjusted. The content of volatile components and fixed carbon contained in the straws is obviously higher than that of the sludge; the contents of carbon and oxygen elements in the two raw materials are higher. The straw is mixed into the sludge for co-carbonization, so that the contents of volatile components, moisture and fixed carbon in the raw materials can be well adjusted, and the improvement of the pyrolysis efficiency of the sludge is facilitated.

Disclosure of Invention

The invention aims to provide a self-heating sludge and straw co-carbonization method and a device, which can perform biomass carbonization in a systematic and self-heating manner and efficiently and cleanly treat sludge and straws.

A self-heating sludge and straw co-carbonization method comprises the following steps: the straw raw materials are sent into a crusher to be crushed, the particle size of the crushed straw is smaller than 100mm, then the crushed straw and wet sludge raw materials are injected into a paddle dryer together to be mixed and dried, the water content of the dried sludge-straw mixture is greatly reduced, and the dried sludge-straw mixture can form slag. The mixture after slagging enters a granulator for granulation, the granular straw sludge mixture enters a cross flow bed for pyrolysis, pyrolysis gas generated by the cross flow bed enters a combustion chamber for combustion to obtain high-temperature flue gas, the high-temperature flue gas is filtered by a calcium oxide filter, one part of the high-temperature flue gas enters the cross flow bed through an air blower to provide heat for pyrolysis of biomass, the other part of the high-temperature flue gas enters a heat exchanger to obtain steam with the temperature of 200-400 ℃ from the heat exchanger, one part of the high-temperature flue gas enters a paddle dryer to serve as a heat source required by drying, and the other part of redundant heat is collected to be used for heat supply of an external environment.

Furthermore, mixing and drying of the straw and sludge raw materials are completed in the paddle dryer, the water content of the treated straw-sludge mixture is controlled to be 20% -30%, granulation of a follow-up granulator is facilitated, balance of heat value is guaranteed, and self-heating of the system is achieved.

Further, pyrolysis gas generated by the cross-flow bed is combusted in the combustion chamber to obtain high-temperature flue gas, acid pollutants are filtered out by the calcium oxide filter, and then the high-temperature flue gas returns to the cross-flow bed to be used as a heat source for pyrolyzing biomass by the cross-flow bed, so that the pyrolysis temperature of the cross-flow bed is not more than 800 ℃, volatilization of heavy metal pollutants in the biomass is controlled, and the heavy metals are solidified in the biochar.

Furthermore, steam from the heat exchanger provides heat for drying the biomass in the paddle dryer, the drying temperature is guaranteed to be 100-200 ℃, and then the steam returns to the heat exchanger to complete thermodynamic cycle.

A method and a device for co-carbonizing self-heating sludge and straws comprise the following steps: the device comprises a straw crusher, a paddle dryer, a biomass granulator, a pyrolysis cross flow bed, a burner, a calcium oxide filter, a shell-and-tube heat exchanger, a three-way valve, a water pump, a heat reservoir, a feeding bin, a feeding hopper, an air blower and a flue gas three-way pipe;

an outlet of the straw crusher is connected with a feeding bin of the paddle dryer, an outlet of mixed biomass of the paddle dryer is connected with an inlet of the biomass granulator, the granulated biomass is fed into the pyrolysis cross flow bed, a pyrolysis gas outlet of the pyrolysis cross flow bed is connected with an inlet of the combustion chamber, a high-temperature flue gas outlet of the combustion chamber is connected with an inlet of the calcium oxide filter, an outlet of the calcium oxide filter is connected with the flue gas three-way valve, one end of the flue gas three-way valve is connected with the air blower, the other end of the flue gas three-way valve is connected with an inlet of the shell-and-tube;

the exhaust steam outlet of the paddle dryer is connected with the gas inlet of the combustion chamber;

the steam outlet of the shell-and-tube heat exchanger is connected with the inlet of a three-way valve, one end of the inlet of the three-way valve is connected with the steam inlet of the paddle dryer, the other end of the inlet of the three-way valve is connected with the inlet of the heat reservoir, the steam outlet of the paddle dryer is connected with the water supply inlet of the shell-and-tube heat exchanger, and a water pump is connected with the water supply inlet.

Furthermore, a slag cooler and an air seal device are arranged at the carbon collection position of the pyrolysis cross flow bed, and the air seal device is also arranged at the bottom of the feed hopper of the cross flow bed.

Compared with the prior art, the invention has the following remarkable advantages: (1) the straws are added into the sludge in the paddle dryer, so that the moisture content of the sludge can be conditioned, the fluidity of the sludge can be increased, and continuous feeding is realized; (2) the content of volatile components and fixed carbon contained in the straws is obviously higher than that of the sludge, the content of C and O elements in the two raw materials is higher, and the content of the volatile components, the content of water and the content of the fixed carbon in the raw materials can be well adjusted by mixing the rice straws into the sludge for co-carbonization, so that the pyrolysis efficiency of the sludge is improved; (3) pyrolysis gas generated by the cross-flow bed is combusted in the combustion chamber to obtain high-temperature flue gas, acid pollutants are filtered out by the calcium oxide filter, and then part of the high-temperature flue gas returns to the cross-flow bed to be used as a heat source for pyrolyzing biomass by the cross-flow bed, so that the pyrolysis temperature of the cross-flow bed is not more than 800 ℃, volatilization of heavy metal pollutants in a pyrolysis mixture is controlled, heavy metals are solidified in biochar, and pollution of the heavy metals in sludge to the environment can be reduced to the maximum extent; (4) steam from the heat exchanger provides heat for drying the biomass in the paddle dryer, so that the drying temperature is ensured to be 100-200 ℃, and heat generated by pyrolysis gas is fully utilized; (5) the whole device can realize the cascade utilization of energy, does not need external heat supply, and has high system operation safety and low cost; (6) efficiently and cleanly disposes the sludge and the straws.

Drawings

FIG. 1 is a schematic diagram of an apparatus for co-carbonizing self-heating sludge and straw according to the present invention.

In the figure: 1-a straw crusher, 2-a paddle dryer, 3-a biomass granulator, 4-a pyrolysis cross flow bed, 5-a burner, 6-a calcium oxide filter, 7-a shell and tube heat exchanger, 8-a three-way valve, 9-a water pump, 10-a heat reservoir, 11-a paddle dryer feed bin, 12-a paddle dryer outlet, 13-a paddle dryer exhaust steam outlet, 14-a burner exhaust steam inlet, 15-a paddle dryer steam inlet, 16-a paddle dryer steam outlet, 17-a biomass granulator feed hopper, 18-a biomass granulator outlet, 19-a pyrolysis cross flow bed feed inlet, 20-a slag cooler, 21-an air seal, 22-a burner inlet, 23-a calcium oxide filter flue gas inlet, 24-a calcium oxide filter solid outlet, 25-blower, 26-flue gas three-way valve, 27-cross flow bed pyrolysis gas outlet, 28-burner outlet, 29-calcium oxide filter flue gas outlet, 30-shell-and-tube heat exchanger flue gas inlet, 31-shell-and-tube heat exchanger steam outlet, 32-shell-and-tube heat exchanger tail gas outlet, and 33-shell-and-tube heat exchanger feed water inlet.

Detailed Description

The invention is further explained below with reference to the drawings.

As shown in fig. 1, an apparatus for co-carbonizing self-heating sludge and straws comprises a straw crusher 1, a paddle dryer 2, a biomass granulator 3, a pyrolysis cross flow bed 4, a burner 5, a calcium oxide filter 6, a shell-and-tube heat exchanger 7, a three-way valve 8, a water pump 9, a heat reservoir 10, a feeding bin 11, a feeding hopper 17, an air blower 25 and a flue gas three-way pipe 26;

an outlet of the straw crusher 1 is connected with a feeding bin 11 of the paddle dryer 2, an outlet 12 of mixed biomass of the paddle dryer 2 is connected with an inlet of a biomass granulator 3, granulated biomass is fed into a feeding hole 19 of the pyrolysis cross flow bed 4, a pyrolysis gas outlet 27 of the pyrolysis cross flow bed 4 is connected with an inlet of the combustion chamber 5, a high-temperature flue gas outlet 28 of the combustion chamber 5 is connected with an inlet of the calcium oxide filter 6, an outlet 29 of the calcium oxide filter 6 is connected with a flue gas three-way valve 26, one end of the flue gas three-way valve 26 is connected with an air blower 25, the other end of the flue gas three-way valve is connected with an inlet of the shell-and-tube heat exchanger;

a dead steam outlet 13 of the paddle dryer 2 is connected with a gas inlet 14 of the combustion chamber 5;

the steam outlet 31 of the shell-and-tube heat exchanger 7 is connected with the inlet of the three-way valve 8, one end of the inlet of the three-way valve 8 is connected with the steam inlet 15 of the paddle dryer 2, the other end of the inlet of the three-way valve 8 is connected with the inlet of the heat reservoir 10, the steam outlet 16 of the paddle dryer 2 is connected with the water supply inlet 33 of the shell-and-tube heat exchanger 7, and the water pump 9 is connected with the water supply inlet 33.

The self-heating sludge and straw co-carbonization method based on the device comprises the following specific steps: the method comprises the steps of feeding straw raw materials into a crusher to be crushed, enabling the particle size of the crushed straw to be smaller than 100mm, then injecting the crushed straw and wet sludge raw materials into a feeding bin 11 of a paddle dryer, mixing and drying the sludge and the straw in the paddle dryer, controlling the water content of the dried biomass material to be 20% -30% at the drying temperature of 100-200 ℃, and facilitating granulation of a follow-up granulator. The generated dead steam enters a dead steam inlet 14 of the combustor 4 from a dead steam outlet 13 of the paddle dryer. The mixed and dried straw and sludge mixture enters a feed hopper 17 of a biomass granulator from an outlet 12 of a paddle dryer, after granulation, the granular straw and sludge mixture enters a feed inlet 19 of a pyrolysis cross flow bed from an outlet 18 of the granulator to be pyrolyzed at the pyrolysis temperature of 600-800 ℃, and a sludge straw co-carbonized product is obtained at the bottom of the pyrolysis cross flow bed after passing through a slag cooler 20 and an air seal machine 21.

Pyrolysis gas generated by pyrolysis enters the combustor 4 from a pyrolysis gas outlet 27 of the cross-flow bed to be combusted to obtain high-temperature flue gas, the temperature of the high-temperature flue gas is 800-1000 ℃, and the high-temperature flue gas enters a flue gas inlet 23 of the calcium oxide filter 6 from an outlet 28 of the combustor. The calcium oxide enters the calcium oxide filter from the upper end, absorbs the acidic pollutants in the flue gas and then is discharged from the outlet 24. The filtered high-temperature flue gas enters the flue gas three-way valve 26 from the flue gas outlet 29 of the calcium oxide filter, and a part of the flue gas enters the cross-flow bed from one end of the three-way valve through the air blower 25 to provide heat for the pyrolysis of biomass, wherein the temperature of the flue gas is 600-800 ℃, so that the pyrolysis temperature of the cross-flow bed is not more than 800 ℃, the volatilization of heavy metal pollutants in the biomass is controlled, and the heavy metal is solidified in the biochar. And the other part of high-temperature flue gas enters the shell-and-tube heat exchanger through one end of the flue gas three-way valve 26, steam with the temperature of 200-400 ℃ is obtained from the shell-and-tube heat exchanger, the steam enters the three-way valve 8 from a steam outlet 31 of the shell-and-tube heat exchanger, one part of steam enters a steam inlet 15 of the paddle dryer and serves as a heat source required by drying, then the steam enters a water supply inlet 33 of the shell-and-tube heat exchanger from a steam outlet 16 of the paddle dryer, and in addition, the other part of the residual heat steam enters the heat reservoir 10 from the other end of.

The invention relates to a method and a device for co-carbonizing self-heating sludge and straws. And (3) the mixed biomass material enters a granulator for granulation treatment, and then the granular biomass material enters a cross-flow bed for pyrolysis to prepare carbon. In the cross-flow bed, biomass is fully pyrolyzed to obtain a target product carbon; in addition, pyrolysis gas collected from the cross flow bed enters a combustion chamber for combustion, high-temperature flue gas after combustion is filtered by a calcium oxide filtering device, one part of the obtained high-temperature flue gas circularly enters the cross flow bed for biomass pyrolysis heat supply, the other part of the obtained high-temperature flue gas enters a shell-and-tube heat exchanger, the obtained steam returns to a paddle dryer for providing heat required by drying biomass materials, and redundant steam heat is collected by a heat reservoir and used for external heat supply. The invention has simple process, fully utilizes the heat of the combusted pyrolysis gas as the heat sources of the cross-flow bed pyrolysis, the drying of the paddle dryer and the external heat supply, does not need the external heat supply in the whole system, and efficiently and cleanly disposes the sludge and the straws.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A co-carbonization method of self-heating sludge and straws is characterized by comprising the following steps: feeding straw raw materials into a crusher to be crushed, enabling the particle size of the crushed straw to be smaller than 100mm, then injecting the crushed straw and wet sludge raw materials into a paddle dryer together for mixing and drying, and reducing the water content of the dried sludge-straw mixture to form slag;

the mixture after slagging enters a granulator for granulation, the granular straw sludge mixture enters a cross flow bed for pyrolysis, pyrolysis gas generated by the cross flow bed enters a combustion chamber for combustion to obtain high-temperature flue gas, the high-temperature flue gas is filtered by a calcium oxide filter, one part of the high-temperature flue gas enters the cross flow bed through an air blower to provide heat for pyrolysis of biomass, the other part of the high-temperature flue gas enters a heat exchanger to obtain steam with the temperature of 200-400 ℃ from the heat exchanger, one part of the high-temperature flue gas enters a paddle dryer to serve as a heat source required by drying, and the other part of redundant heat is collected to be used for heat supply of an external environment.

2. The method for co-carbonizing self-heating sludge and straws according to claim 1, which is characterized in that: straw and sludge raw materials enter a paddle dryer, mixing and drying are completed in the paddle dryer, the water content of the dried straw-sludge mixture is controlled to be 20% -30%, granulation of a follow-up granulator is facilitated, balance of heat value is guaranteed, and self-heating of the system is achieved.

3. The method for co-carbonizing self-heating sludge and straws according to claim 1, which is characterized in that: pyrolysis gas generated by the cross-flow bed is combusted in the combustion chamber to obtain high-temperature flue gas, acid pollutants are filtered out by the calcium oxide filter, and then part of the high-temperature flue gas returns to the cross-flow bed to be used as a heat source for pyrolyzing biomass by the cross-flow bed, so that the pyrolysis temperature in the cross-flow bed is ensured to be not more than 800 ℃, volatilization of heavy metal pollutants in the biomass is controlled, and heavy metals are solidified in the biochar.

4. The method for co-carbonizing self-heating sludge and straws according to claim 1, which is characterized in that: steam from the heat exchanger provides heat for drying the biomass in the paddle dryer, the drying temperature is guaranteed to be 100-200 ℃, and then the steam returns to the heat exchanger to complete thermodynamic cycle.

5. The utility model provides a device of self-heating mud and straw carbonization altogether which characterized in that: the biomass pyrolysis device comprises a straw crusher (1), a paddle dryer (2), a biomass granulator (3), a pyrolysis cross flow bed (4), a burner (5), a calcium oxide filter (6), a shell-and-tube heat exchanger (7), a three-way valve (8), a water pump (9), a heat reservoir (10), a feeding bin (11), a feeding hopper (17), an air blower (25) and a flue gas three-way pipe (26);

an outlet of the straw crusher (1) is connected with a feeding bin (11) of the paddle dryer (2), an outlet (12) of mixed biomass of the paddle dryer (2) is connected with an inlet of the biomass granulator (3), a feeding hopper (17) is arranged at an inlet of the biomass granulator (3), granulated biomass is fed into a feeding hole (19) of the pyrolysis cross flow bed through an outlet (18) of the biomass granulator, a pyrolysis gas outlet (27) of the pyrolysis cross flow bed (4) is connected with an inlet (22) of the combustion chamber (5), a high-temperature flue gas outlet (28) of the combustion chamber (5) is connected with an inlet (23) of the calcium oxide filter (6), an outlet (29) of the calcium oxide filter (6) is connected with a flue gas three-way valve (26), one end of the flue gas three-way valve (26) is connected with a 25, the other end of the flue gas three-way valve is connected with an inlet (30) of the shell-and-tube;

a dead steam outlet (13) of the paddle dryer (2) is connected with a gas inlet (14) of the combustion chamber (5);

a steam outlet (31) of the shell-and-tube heat exchanger (7) is connected with an inlet of a three-way valve (8), one end of the inlet of the three-way valve (8) is connected with a steam inlet (15) of the paddle dryer (2), the other end of the inlet of the three-way valve is connected with an inlet of a heat reservoir (10), a steam outlet (16) of the paddle dryer (2) is connected with a water supply inlet (33) of the shell-and-tube heat exchanger (7), and a water pump (9) is connected with the water supply inlet (33) of the shell-.

6. The device for co-carbonizing self-heating sludge and straws according to claim 5, wherein: the carbon collecting position of the pyrolysis generation cross flow bed (4) is provided with a slag cooler (20) and an air seal device (21), a feeding hole (19) of the pyrolysis cross flow bed is also provided with a feeding funnel, and the bottom of the feeding funnel is also provided with the air seal device.