阅读说明：本技术 火电厂烟气再循环耦合污泥干化在线掺烧系统 (Flue gas recirculation coupling sludge drying on-line mixed combustion system of thermal power plant ) 是由 张润元 乔岗杰 刘红刚 王亚琴 赵云凯 骆丁玲 延彪 武建芳 石龙龙 赵耀芳 何 于 2019-11-22 设计创作，主要内容包括：本发明提供一种火电厂烟气再循环耦合污泥干化在线掺烧系统,属于锅炉烟气余热利用及污泥干化领域,以解决目前系统中恶臭气体泄漏、烟气中携带有毒有害有机物造成环境污染且影响粉尘和硫的达标排放、系统运行不够灵活及低负荷时锅炉NO<Sub>x</Sub>排放超标的问题。污泥干化系统中的生石灰称重输送机将湿污泥掺混生石灰后经第一螺旋输送机和污泥切条机送入一个或两个干化机后,由循环流化床发电系统的120-150℃的高温烟气进入干化机干化,干化后的污泥经干污泥称重输送机送到掺料仓与煤粉混合后进入锅炉燃烧,从干化机出来的烟气作为锅炉一次风再循环回送到炉膛,将循环流化床发电系统与污泥干化系统结合,在利用烟气余热干化湿污泥后又将干污泥作为燃料燃烧发电。(The invention provides a flue gas recirculation coupling sludge drying online co-combustion system of a thermal power plant, belongs to the field of boiler flue gas waste heat utilization and sludge drying, and aims to solve the problems that malodorous gas in the conventional system leaks, toxic and harmful organic matters are carried in flue gas, environmental pollution is caused, the standard discharge of dust and sulfur is influenced, the system is not flexible enough in operation, and NO of a boiler is not discharged at low load x The emission exceeds the standard. Mixing wet sludge with quicklime by a quicklime weighing conveyor in the sludge drying system, sending the mixture into one or two drying machines by a first screw conveyor and a sludge slitter, then sending the mixture into the drying machines for drying by high-temperature flue gas at the temperature of 150 ℃ of 120 plus materials of a circulating fluidized bed power generation system, and drying the dried sludge by a dry sludge weighing conveyorThe flue gas from the drier is used as primary air of the boiler and then is recycled and returned to the hearth, the circulating fluidized bed power generation system is combined with the sludge drying system, and the dry sludge is used as fuel to be combusted and generate power after the wet sludge is dried by using the waste heat of the flue gas.)

1. The utility model provides an online system of burning of mixing of thermal power plant's flue gas recirculation coupling sludge drying which characterized in that, includes circulating fluidized bed power generation system and sludge drying system, wherein:

the circulating fluidized bed power generation system comprises a weighing coal feeder (16), a blending bin (8), a boiler (9), an air preheater (10), a dust remover (11), a desulfurizing tower (12), a chimney (13) and a third fan (19), wherein the weighing coal feeder (16), the blending bin (8), the boiler (9), the air preheater (10), the dust remover (11), the desulfurizing tower (12) and the chimney (13) are sequentially connected through a pipeline, an inlet of the third fan (19) is connected with an air source, and an outlet of the third fan (19) is connected with an air side inlet of the air preheater (10);

the sludge drying system comprises a quick lime weighing conveyor (14), a wet sludge bin (15), a first screw conveyor (1), a sludge slitter (2), a first drier (3), a second drier (4), a second screw conveyor (5), a dry sludge bin (6) and a dry sludge weighing conveyor (7), wherein the quick lime weighing conveyor (14), the wet sludge bin (15), the first screw conveyor (1) and the sludge slitter (2) are sequentially connected through a pipeline, sludge inlets of the first drier (3) and the second drier (4) are connected with a sludge outlet of the sludge slitter (2) through a pipeline, sludge outlets of the first drier (3) and the second drier (4) are connected with a sludge inlet of the second screw conveyor (5) through a pipeline, a sludge outlet of the second screw conveyor (5) is connected with a sludge inlet of the dry sludge bin (6), a first sludge outlet of the dry sludge bin (6) is connected with a sludge inlet of the dry sludge weighing conveyor (7), and a second sludge outlet of the dry sludge bin (6) is connected with other equipment;

the sludge outlet of the dry sludge weighing conveyor (7) is connected with the sludge inlet of the mixing bin (8), the flue gas side outlet of the air preheater (10) is connected with the flue gas inlets of the first drier (3) and the second drier (4) through pipelines, the flue gas side outlet of the air preheater (10) is connected with the inlets of the first drier (3) and the second drier (4) through pipelines, a first fan (17) is arranged on the pipeline between the flue gas side outlet of the first drier (3) and the flue gas inlet of the second drier (4), the flue gas outlets of the first drier (3) and the second drier (4) are connected with the inlet of a third fan (19) through a pipeline, the air side outlet of the air preheater (10) is connected with the primary air inlet of the boiler (9), the flue gas outlet of the boiler (9) is connected with the flue gas side inlet of the air preheater (10), a second fan (18) is arranged on the pipeline between the flue gas outlets of the first drier (3) and the second drier (4) and the inlet of the third fan (19), the smoke outlets of the wet sludge bin (15), the dry sludge bin (6) and the admixture bin (8) are connected with the inlet of a second fan (18);

a first valve (20) and a second valve (21) are respectively arranged on a pipeline between a sludge outlet of the sludge slitter (2) and a sludge inlet of the first drier (3) and the second drier (4), a third valve (22) and a fourth valve (23) are respectively arranged on a pipeline between the sludge outlet of the first drier (3) and the sludge inlet of the second drier (4) and a sludge inlet of the second screw conveyor (5), a fifth valve (24) is arranged on a pipeline between a second sludge outlet of the dry sludge bin (6) and other equipment, a sixth valve (25) is arranged on a pipeline between a first sludge outlet of the dry sludge bin (6) and a sludge inlet of the dry sludge weighing conveyor (7), a seventh valve (26) is arranged on a pipeline between a smoke outlet of the first drier (3) and an inlet of the second fan (18), and an eighth valve (27) is arranged on a pipeline between an outlet of the second fan (18) and an inlet of the third fan (19), a ninth valve (28) is arranged on the pipeline where the first fan (17) is arranged, a tenth valve (29) is arranged on the pipeline between the inlet of the third fan (19) and the air source, and an eleventh valve (30) is arranged on the pipeline between the sludge outlet of the first drying machine (3) and the sludge inlet of the second drying machine (4).

2. The thermal power plant flue gas recirculation coupling sludge drying online blending combustion system as claimed in claim 1, wherein the sludge drying system further comprises a first sludge moisture content online monitor (31), a second sludge moisture content online monitor (32) and a third sludge moisture content online monitor (33), the first sludge moisture content online monitor (31) and the second sludge moisture content online monitor (32) are respectively arranged on the pipelines between the sludge outlet of the first drier (3) and the second drier (4) and the sludge inlet of the second screw conveyor (5), and the third sludge moisture content online monitor (33) is arranged on the pipelines between the sludge outlet of the second screw conveyor (5) and the sludge inlet of the dry sludge bin (6).

3. The thermal power plant flue gas recirculation coupling sludge drying online blending combustion system as claimed in claim 1, wherein the first drying machine (3) and the second drying machine (4) are both drum-type drying machines.

Technical Field

The invention relates to the technical field of boiler flue gas waste heat utilization and sludge drying utilization of a thermal power plant, in particular to a flue gas recirculation coupling sludge drying online co-combustion system of the thermal power plant.

Background

In recent years, the requirement for environmental protection is getting stricter, and particularly, the sludge yield is getting larger and larger along with the increasing scale of sewage treatment plants. The sludge has the characteristics of high water content, huge volume and the like, is extremely inconvenient in the processes of storage, transportation, loading and unloading and the like, and has high potential environmental safety risk and hidden danger, so that the sludge is inevitably subjected to harmless, quantitative reduction and resource treatment by adopting effective means. At present, the sludge treatment modes mainly comprise landfill, composting, natural drying or incineration and the like. Practice shows that the sludge drying and incineration technology has the characteristics of small occupied area, rapid treatment, large amount, obvious reduction and the like, can furthest realize the reduction and the resource of the sludge, and has good application prospect.

A boiler in a thermal power plant is equipment for burning pulverized coal to heat water and generate steam, and a large amount of pulverized coal is consumed in the burning process and high-temperature flue gas is amplified. Because the smoke discharge amount is large and the temperature is high, the smoke discharged by the boiler contains huge heat, and can be used as an ideal heat source for sludge drying. The dried sludge can be directly sent into a fuel system of a boiler for combustion and power generation. Meanwhile, for the circulating fluidized bed boiler, in order to ensure fluidization at low load, the oxygen content in the hearth is higher, and NO exists_xThe problem of difficult control is that the oxygen content can be reduced and NO can be ensured by recycling the flue gas after sludge drying to the boiler hearth_xDischarging after reaching the standard. Therefore, the sludge is incinerated to generate power after being dried by recycling the flue gas of the thermal power plant, so that the waste heat of the flue gas can be utilized, the heat loss of the flue gas is reduced, the efficiency of the boiler is improved, the sludge can be fed into the boiler to be combusted, the heat value of the sludge is utilized to heat the feed water, the fuel consumption is reduced, and the NO of the boiler can be reduced_xThe amount of production.

In the existing sludge drying blending combustion system, a conveyor conveys a mixture of dry sludge and coal to a boiler furnace for combustion, a flue gas inlet of a drying bin is connected with a flue at an outlet of the boiler furnace through an air exhaust pipeline, and a flue gas outlet of the drying bin is connected with a flue at an outlet of the boiler furnace through an air return pipeline. The current systems suffer from the following disadvantages: (1) when the wet sludge is dried by using the flue gas discharged by the boiler, the flue gas is discharged at high temperature of 250 ℃ by using the boiler 240, and a large amount of malodorous gases of different types of organic matters can be generated in the sludge at the temperature, so that the malodorous gases are leaked to cause atmosphere pollution; (2) drying bin outletThe flue gas is directly sent to a flue at the outlet of a hearth, is treated by a subsequent dust remover and a desulfurizing tower and then is exhausted, only dust and inorganic sulfur in the outlet flue gas can be removed in the treatment process, part of hydrocarbon organic matters and organic sulfur in the flue gas can be attached to the dust remover to reduce the dust removal efficiency, part of hydrocarbon organic matters and organic sulfur in the flue gas can be enriched in the desulfurizing slurry to poison the desulfurizing slurry to reduce the desulfurizing efficiency, and the rest of the flue gas can be discharged into the atmosphere along with the flue gas to pollute the environment and influence the standard emission of the dust and the sulfur; in addition, boiler NO at low load_xThe emission is easy to exceed the standard. (3) The system is not flexible enough to operate.

Disclosure of Invention

Aims to solve the problems of malodorous gas leakage, environmental pollution caused by toxic and harmful organic matters carried in flue gas, dust and sulfur emission reaching the standard, inflexible system operation and low load of boiler NO in the prior sludge drying mixed combustion system_xThe invention provides a flue gas recirculation coupling sludge drying online co-combustion system of a thermal power plant, and aims to solve the technical problem of excessive emission.

In order to solve the technical problems, the invention adopts the technical scheme that:

the utility model provides a flue gas recirculation coupling sludge drying of thermal power plant mixes burning system on line, its includes circulating fluidized bed power generation system and sludge drying system, wherein: the circulating fluidized bed power generation system comprises a weighing coal feeder, a blending bin, a boiler, an air preheater, a dust remover, a desulfurizing tower, a chimney and a third fan, wherein the weighing coal feeder, the blending bin, the boiler, the air preheater, the dust remover, the desulfurizing tower and the chimney are sequentially connected through a pipeline, an inlet of the third fan is connected with an air source, and an outlet of the third fan is connected with an air side inlet of the air preheater;

the sludge drying system comprises a quick lime weighing conveyor, a wet sludge bin, a first screw conveyor, a sludge slitter, a first drier, a second screw conveyor, a dry sludge bin and a dry sludge weighing conveyor, wherein the quick lime weighing conveyor, the wet sludge bin, the first screw conveyor and the sludge slitter are sequentially connected through a pipeline;

the sludge outlet of the dry sludge weighing conveyor is connected with the sludge inlet of the blending bin, the flue gas side outlet of the air preheater is connected with the flue gas inlets of the first drier and the second drier through a pipeline, a first fan is arranged on the pipeline between the flue gas side outlet of the air preheater and the flue gas inlets of the first drier and the second drier, the flue gas outlets of the first drier and the second drier are connected with the inlet of a third fan through a pipeline, the air side outlet of the air preheater is connected with the primary air inlet of the boiler, the flue gas outlet of the boiler is connected with the flue gas side inlet of the air preheater, a second fan is arranged on the pipeline between the flue gas outlets of the first drier and the second drier and the inlet of the third fan, and the flue gas outlets of the wet sludge bin, the dry sludge bin and the blending bin are connected with the inlet of;

a first valve and a second valve are respectively arranged on a pipeline between a sludge outlet of the sludge slitter and a sludge inlet of the first drier and the second drier, a third valve and a fourth valve are respectively arranged on a pipeline between the sludge outlet of the first drier and the sludge inlet of the second screw conveyer, a fifth valve is arranged on a pipeline between a second sludge outlet of the dry sludge bin and other equipment, a sixth valve is arranged on a pipeline between the first sludge outlet of the dry sludge bin and a sludge inlet of the dry sludge weighing conveyer, a seventh valve is arranged on a pipeline between a flue gas outlet of the first drier and an inlet of the second fan, an eighth valve is arranged on a pipeline between an outlet of the second fan and an inlet of the third fan, a ninth valve is arranged on a pipeline where the first fan is positioned, and a tenth valve is arranged on a pipeline between an inlet of the third fan and an air source, an eleventh valve is arranged on a pipeline between the sludge outlet of the first drying machine and the sludge inlet of the second drying machine.

Optionally, the sludge drying system further comprises a first sludge moisture content on-line monitor, a second sludge moisture content on-line monitor and a third sludge moisture content on-line monitor, the first sludge moisture content on-line monitor and the second sludge moisture content on-line monitor are respectively arranged on the pipelines between the sludge outlets of the first drying machine and the second drying machine and the sludge inlet of the second screw conveyor, and the third sludge moisture content on-line monitor is arranged on the pipelines between the sludge outlet of the second screw conveyor and the sludge inlet of the dry sludge bin.

Optionally, the first drying machine and the second drying machine are both drum-type drying machines.

The invention has the beneficial effects that:

wet sludge is mixed with quick lime by a quick lime weighing conveyer in a sludge drying system and then is sent into one or two drying machines by a first screw conveyer and a sludge slitter, high-temperature flue gas with the temperature of 150 ℃ from a circulating fluidized bed power generation system enters the drying machines for drying, dried sludge is sent into a mixing bin by a dry sludge weighing conveyer and then is mixed with pulverized coal to enter a boiler for combustion, the flue gas coming out of the drying machines is recycled as primary air of the boiler and then is returned to a hearth, thereby the circulating fluidized bed power generation system is combined with the sludge drying system, the wet sludge is dried by using the waste heat of the flue gas, the dry sludge is used as fuel for combustion power generation, the real-time drying and the mixing combustion can be realized, the thermal efficiency of the system is improved, the sludge is reduced, recycled and harmlessly utilized, and the NO of the boiler is reduced by using the flue gas recirculation_xThe amount of production of (c). Therefore, compared with the background art, the invention has the following advantages:

1. the quick lime can be added into the wet sludge through the quick lime weighing conveyor, so that part of moisture in the wet sludge can be removed in advance, part of sulfur in the wet sludge can be removed, and the load of a drier and a flue gas treatment system is reduced.

2. Drying is carried out by using the high-temperature flue gas at the temperature of 120-150 ℃ in the boiler, so that the generation of malodorous gas caused by volatilization of different types of organic matters in wet sludge is avoided; through setting up first fan, second fan and third fan, can balance ventilate and guarantee wet sludge warehouse, dry sludge warehouse, mix feed bin, first mummification machine and second mummification machine and be the negative pressure state, avoid dust and stink to leak and the polluted environment.

3. Wet sludge is dried through a flue gas recirculation system of a thermal power plant, and then the sludge is mixed and burnt in real time, namely, the sludge is burnt immediately after being dried, so that the waste heat of the flue gas can be utilized, the heat loss of the discharged smoke is reduced, the efficiency of a boiler is improved, the sludge can be fed into the boiler to be burnt, the heat value of the sludge is utilized to heat feed water, and the fuel consumption is reduced.

4. On one hand, the smoke from the smoke outlets of the first drier and the second drier is recycled and returned to the boiler to participate in combustion, so that the organic matter volatile components carried in the smoke at the outlets can be combusted and decomposed at high temperature, and the pressure of a smoke treatment system is reduced; on the other hand, the oxygen content of the boiler can be reduced after returning to reduce NO_xThe generated amount provides conditions, the dust removal efficiency of the dust remover cannot be reduced, and the standard emission of dust and sulfur cannot be influenced.

5. By arranging the two drying machines, the system is flexible in operation mode and large in sludge treatment capacity, wet sludge with high water content can be treated, and the air quantity of a fan, the rotating speed of the drying machines and the series-parallel connection mode can be adjusted according to the drying capacity of the sludge and the requirement of the dried water content.

6. The blending combustion proportion of the sludge can be determined by the metering of a weighing coal feeder and a dry sludge weighing conveyor.

7. The sludge drying is carried out by using the flue gas, the oxygen content in the drying machine can be controlled within 6 percent, and the drying system can be prevented from exploding.

8. The flue gas with higher temperature after drying is recycled to the air supply system of the boiler, the cold air temperature of the air preheater can be improved, and the air heater can be removed from the boiler at the place where low-sulfur coal is used and the environment temperature is higher, so that the investment is saved, and the loss caused by the fault of the air heater can be avoided.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the flue gas recirculation coupling sludge drying online co-firing system in the thermal power plant in this embodiment includes a circulating fluidized bed power generation system and a sludge drying system, wherein: the circulating fluidized bed power generation system comprises a weighing coal feeder 16, a blending bin 8, a boiler 9, an air preheater 10, a dust remover 11, a desulfurizing tower 12, a chimney 13 and a third fan 19, wherein the weighing coal feeder 16, the blending bin 8, the boiler 9, the air preheater 10, the dust remover 11, the desulfurizing tower 12 and the chimney 13 are sequentially connected through a pipeline, an inlet of the third fan 19 is connected with an air source, and an outlet of the third fan 19 is connected with an air side inlet of the air preheater 10; the sludge drying system comprises a quicklime weighing conveyer 14, a wet sludge bin 15, a first screw conveyer 1, a sludge slitter 2, a first drier 3, a second drier 4, a second screw conveyer 5, a dry sludge bin 6 and a dry sludge weighing conveyer 7, the quick lime weighing conveyor 14, the wet sludge bin 15, the first screw conveyor 1 and the sludge slitter 2 are sequentially connected through a pipeline, sludge inlets of the first drier 3 and the second drier 4 are connected with a sludge outlet of the sludge slitter 2 through pipelines, sludge outlets of the first drier 3 and the second drier 4 are connected with a sludge inlet of the second screw conveyor 5 through a pipeline, a sludge outlet of the second screw conveyor 5 is connected with a sludge inlet of the dry sludge bin 6, a first sludge outlet of the dry sludge bin 6 is connected with a sludge inlet of the dry sludge weighing conveyor 7, and a second sludge outlet of the dry sludge bin 6 is connected with other equipment; a sludge outlet of the dry sludge weighing conveyor 7 is connected with a sludge inlet of the admixture bin 8, a smoke side outlet of the air preheater 10 is connected with smoke inlets of the first drier 3 and the second drier 4 through pipelines, a first fan 17 is arranged on a pipeline between the smoke side outlet of the air preheater 10 and the smoke inlets of the first drier 3 and the second drier 4, the smoke outlets of the first drier 3 and the second drier 4 are both connected with an inlet of a third fan 19 through pipelines, an air side outlet of the air preheater 10 is connected with a primary air inlet of the boiler 9, a smoke outlet of the boiler 9 is connected with the smoke side inlet of the air preheater 10, a second fan 18 is arranged on a pipeline between the smoke outlets of the first drier 3 and the second drier 4 and an inlet of the third fan 19, smoke outlets of the wet sludge bin 15, the dry sludge bin 6 and the admixture bin 8 are connected with an inlet of the second fan 18, a first valve 20 and a second valve 21 are respectively arranged on pipelines between a sludge outlet of the sludge slitter 2 and sludge inlets of the first drier 3 and the second drier 4, a third valve 22 and a fourth valve 23 are respectively arranged on pipelines between the sludge outlets of the first drier 3 and the second drier 4 and the sludge inlet of the second screw conveyer 5, a fifth valve 24 is arranged on a pipeline between the second sludge outlet of the dry sludge bin 6 and other equipment, a sixth valve 25 is arranged on a pipeline between the first sludge outlet of the dry sludge bin 6 and the sludge inlet of the dry sludge weighing conveyer 7, a seventh valve 26 is arranged on a pipeline between a flue gas outlet of the first drier 3 and an inlet of the second fan 18, an eighth valve 27 is arranged on a pipeline between an outlet of the second fan 18 and an inlet of the third fan 19, and a ninth valve 28 is arranged on a pipeline where the first fan 17 is arranged, a tenth valve 29 is arranged on a pipeline between the inlet of the third fan 19 and the air source, and an eleventh valve 30 is arranged on a pipeline between the sludge outlet of the first drier 3 and the sludge inlet of the second drier 4.

Optionally, the sludge drying system further includes a first sludge moisture content online monitor 31, a second sludge moisture content online monitor 32 and a third sludge moisture content online monitor 33, the first sludge moisture content online monitor 31 and the second sludge moisture content online monitor 32 are respectively arranged on the pipelines between the sludge outlet of the first drying machine 3 and the second drying machine 4 and the sludge inlet of the second screw conveyor 5, and the third sludge moisture content online monitor 33 is arranged on the pipelines between the sludge outlet of the second screw conveyor 5 and the sludge inlet of the dry sludge bin 6.

Optionally, the first dryer 3 and the second dryer 4 are both drum dryers. The first screw conveyor 1, the second screw conveyor 5 and the lime weighing conveyor 14 can be adjusted in a variable speed mode. The first fan 17, the second fan 18 and the third fan 19 are all adjustable at variable speeds.

When the wet sludge wet-type gas-liquid separator is used, according to the amount of wet sludge from outside a thermal power plant, a certain proportion of quicklime is mixed by the quicklime weighing conveyor 14 and enters the wet sludge bin 15 to be mixed with the wet sludge stored in the wet sludge bin 15, so that on one hand, part of moisture in the wet sludge is pre-removed in advance, on the other hand, part of sulfur in the wet sludge can be removed, and the load of subsequent equipment is reduced. Wet sludge mixed with quick lime is sent into a sludge slitter 2 through a first screw conveyer 1, the wet sludge enters a first drier 3 and/or a second drier 4 for drying after the sludge slitter 2 pre-slivers the mixed wet sludge, the dried sludge is sent into a dry sludge bin 6 through a second screw conveyer 5, and dry sludge coming out of the bottom of the dry sludge bin 6 is sent into a blending bin 8 through a dry sludge weighing conveyer 7, and is sent to other places for utilization.

The fuel mixed with the sludge and mixed with the sludge is mixed by a weighing coal feeder 16 and a dry sludge weighing conveyer 7 and then is sent into a boiler 9 for combustion. High-temperature flue gas with the temperature of 120-150 ℃ from the flue gas side outlet of the air preheater 10 is introduced into the first drying machine 3 and/or the second drying machine 4 by the first fan 17, and the wet sludge entering the first drying machine 3 and/or the second drying machine 4 is dried by the hot flue gas. The dried flue gas from the flue gas outlet of the first drying machine 3 and/or the second drying machine 4 is recycled to the air supply system of the boiler through the second fan 18 and the air side inlet of the air preheater 10. The wet sludge bin 15, the dry sludge bin 6 and the blending bin 8 are connected with the flue gas outlet pipes of the first drier 3 and the second drier 4 through pipelines, and the output of the first fan 17, the second fan 18 and the third fan 19 is adjusted to keep the negative pressure state in the first drier 3, the second drier 4, the wet sludge bin 15, the dry sludge bin 6 and the blending bin 8, so that dust and odor leakage can be avoided.

In the operation process, the air quantity of the first fan 17, the air quantity of the second fan 18 and the air quantity of the third fan 19, the rotating speed of the first drier 3 and/or the rotating speed of the second drier 4 and the series-parallel connection mode can be adjusted according to the requirements of the drying quantity and the dried water content of the sludge. For example, when the sludge drying amount is required to be increased, the first valve 20, the second valve 21, the third valve 22 and the fourth valve 23 may be opened simultaneously, the eleventh valve 30 may be closed, and at this time, the first drying machine 3 and the second drying machine 4 enter a parallel operation state, and the first drying machine 3 and the second drying machine 4 simultaneously enter and output sludge, so that the output of the first fan 17 and the second fan 18 may be further increased, so that the hot air amount in the first drying machine 3 and the second drying machine 4 may be increased, and the rotation speed of the first drying machine 3 and the second drying machine 4 may be increased, so that the output of the first drying machine 3 and the second drying machine 4 may be increased; when the moisture content of the dry sludge is required to be reduced, the first valve 20, the eleventh valve 30 and the fourth valve 23 can be simultaneously opened, the second valve 21 and the third valve 22 are closed, at the moment, the first drier 3 and the second drier 4 enter a serial operation state, wet sludge sequentially enters the first drier 3 and the second drier 4, or the output of the first fan 17 and the second fan 18 is increased in a parallel state, so that the hot air quantity in the drier is increased, and meanwhile, the rotating speed of the drier can be increased, so that the output of the first drier 3 and the second drier 4 is increased. When the drying amount of the sludge is required to be reduced or the water content of the sludge is required to be increased, the air quantity of a fan, the rotating speed of a drier and a series-parallel connection mode can be correspondingly adjusted. The first sludge water content on-line monitor 31, the second sludge water content on-line monitor 32 and the third sludge water content on-line monitor 33 can be used for monitoring the sludge water content of the sludge outlets of the first drier 3, the second drier 4 and the second screw conveyer 5, and are convenient to operate and adjust. The valves arranged on the pipelines can adjust and shut off the sludge flow and the flue gas flow.

In the invention, the sludge is dried by the high-temperature flue gas conveyed by the first fan 17 in the first drier 3 and/or the second drier 4, and the dried sludge is mixed with coal powder in the blending bin 8 and then is conveyed into the boiler 9 for combustion. The process can realize the drying and burning of the sludge, so that the waste heat in the flue gas discharged by the boiler 9 can be utilized, the heat loss of the flue gas is reduced, the boiler efficiency is improved, the sludge can be fed into the boiler 9 to be burnt, the heat value of the sludge is utilized to heat the feed water, the fuel consumption is reduced, and the reduction, the recycling and the harmless treatment of the sludge are realized.

In the invention, the dried hot flue gas carrying a large amount of pollutants such as organic volatile matters is sent into an air supply system of the boiler 9 by the second fan 18. Through flue gas recirculation, pollutants such as organic matter volatile compounds can be decomposed at high temperature in the hearth, and harmless treatment of the pollutants is realized.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.