A sorting type biomass-fired circulating fluidized bed boiler feeding system

Abstract

The present invention belongs to the technical field of boilers, and particularly relates to a sorting type biomass-fired circulating fluidized bed boiler feeding system. The technical scheme is as follows: a sorting type biomass-fired circulating fluidized bed boiler feeding system, comprising a circulating fluidized bed boiler and a buffer bin, a circulating fluidized bed boiler feeding port is connected between the circulating fluidized boiler and the buffer bin, a biomass feed port is connected to the buffer bin, a sorting type mobile feeding device is installed in the buffer bin, a blower is connected to the bottom of the sorting type mobile feeding device through a pipeline, a dust collector is connected to the top of the buffer bin through a pipeline; an induced draft fan is connected to the top of the circulating fluidized bed boiler through a pipeline. The present invention provides a sorting type biomass feeding and a circulating fluidized bed boiler feeding system with a relatively low negative pressure in the furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of boilers, and in particular relates to a sorting-type biomass-burning circulating fluidized bed boiler feeding system. Background Art

[0002] Biomass energy has attracted wide attention due to its advantages such as environmental friendliness, renewable nature, large reserves, and the ability to replace conventional fossil fuels. Circulating fluidized bed boiler technology has many advantages such as wide adaptability to coal types, high combustion efficiency, and low pollutant emissions. And as the pressure for energy conservation and emission reduction increases globally, the development of circulating fluidized bed boilers that burn biomass has become a technical route for the efficient use of clean energy.

[0003] Although different manufacturers have designed and put into production various circulating fluidized bed boilers and biomass feeding systems that burn biomass fuels, the high soil content of domestic biomass causes the ash concentration in the circulating fluidized bed boiler to be too high, causing a series of problems such as low boiler bed temperature, large positive pressure at the feed port, and low combustion efficiency. The positive pressure at the feed port causes a series of problems such as flue gas backflow at the feed port, silo fire, and feeding equipment blockage during boiler feeding. To solve the above problems, it is necessary to use methods such as boiler ash discharge and furnace negative pressure (over -2000Pa) to alleviate them. However, although boiler ash discharge can reduce the ash concentration in the furnace, this method will directly discharge the high-temperature (over 700°C) circulating ash or heat the boiler feed water through an ash cooler, which greatly reduces the economy of the boiler. The method of raising the negative pressure in the furnace will have a certain safety impact on the boiler structure.

[0004] Different units have proposed different patents for biomass boilers to achieve smooth delivery of biomass fuels and solve the problems of positive furnace pressure, flue gas backflow or blockage that may exist in biomass feeding. For example, the patent with publication number CN210619077U proposes to achieve feeding and prevent flue gas backflow by setting up a series of equipment such as biomass silos, activators, feeders, unloading belt conveyors, and screw feeders. This patent has defects such as complex system, easy fuel blockage, and inability to achieve continuous feeding after flue gas backflow; the patent with publication number CN210014350U The patent proposes to feed by an ejector device to prevent positive pressure in the furnace. Although the idea is novel, it does not consider how to achieve smooth feeding on a fluidized bed boiler, has certain limitations, and does not consider the problem that excessive soil content will reduce boiler efficiency; the patent with publication number CN208886819U proposes to divide the biomass silo into different areas and achieve feeding stability by controlling the feeding rate of different silos. It does not consider that the back pressure at the feeding point may have a great impact on the safety and stability of the feeding system, nor does it consider the problems caused by the high soil content of biomass. The patent with publication number CN109852428A provides a method for delivering biomass fuel to a positive pressure gasification furnace, but it has a complex system and does not consider the complexity of the circulating fluidized bed boiler fuel and the high soil content; the patent with publication number CN212402697U can achieve positive pressure continuous feeding, but its system is complex and has many mechanical structures. Once a mechanical failure occurs during operation, it is difficult to ensure the stable operation of the boiler, and the impact of the soil content on the boiler is not considered; the patent with publication number CN209431449U expects to use a screw feeder The positive pressure tempering in the furnace is achieved by means of sealing air on the feeding screw, etc. This technology has been proven to be impossible to achieve on the existing biomass boilers, because if the feeding screw is close to the air side and cannot be sealed, the sealing air will not enter the furnace but will aggravate the backflow of positive pressure in the boiler; the patent with publication number CN108179031A provides an adjustable positive pressure biomass feeding system, which mainly uses a rotating blade to generate a pressure head to achieve positive pressure feeding. The system is complex and requires multiple subsequent processes for biomass fuel to achieve feeding. It also does not consider the impact of high soil content in biomass on the boiler.

[0005] The above-mentioned patents either have systems that are too complex and difficult to implement, or fail to take into account the characteristics of actual biomass and are too idealistic, or have difficulty in overcoming the positive pressure in the fluidized bed boiler. In addition, the above-mentioned patents have not considered using the feeding process to solve the problems of high positive pressure in the furnace and poor combustion efficiency caused by the high soil content of domestic biomass.

[0006] The present invention aims to solve the problem of high soil content in biomass fuel by adopting a sorting biomass feeding system process, which can reduce the ash content of biomass entering the furnace from the source, and assist with the method of pulling a lower negative pressure in the furnace to achieve the goals of no backflow of flue gas from the boiler furnace feeding port and high boiler combustion efficiency, thereby greatly improving the economy, stability and safety of circulating fluidized bed boilers burning biomass. Summary of the invention

[0007] In order to solve the above problems existing in the prior art, the object of the present invention is to provide a circulating fluidized bed boiler feeding system with sorting biomass feeding and lower negative pressure in the furnace.

[0008] The technical solution adopted by the present invention is:

[0009] A sorting type biomass-fired circulating fluidized bed boiler feeding system comprises a circulating fluidized bed boiler and a buffer bin, a circulating fluidized bed boiler feeding port is connected between the circulating fluidized bed boiler and the buffer bin, a biomass feed port is connected to the buffer bin, a sorting type mobile feeding device is installed in the buffer bin, a blower is connected to the bottom of the sorting type mobile feeding device through a pipeline, a dust collector is connected to the top of the buffer bin through a pipeline; an induced draft fan is connected to the top of the circulating fluidized bed boiler through a pipeline.

[0010] The biomass fuel enters the buffer bin from the biomass feed port, and the wind sent by the blower enters the sorting mobile feeding equipment. Under the action of the upward airflow coming out of the sorting mobile feeding equipment, the biomass fuel is evenly distributed on the sorting mobile feeding equipment through the buffer bin. The rising airflow carries the dust in the biomass fuel to the upper part of the buffer bin to form a dust-laden airflow, and the dust-laden airflow enters the dust collector. The biomass fuel with dust removed is sent to the feed port of the circulating fluidized bed boiler by the forward-moving sorting mobile feeding equipment to enter the furnace for combustion. Since the dust in the biomass is removed, the ash concentration in the circulating fluidized bed boiler is greatly reduced. At this time, the negative pressure of the furnace of the circulating fluidized bed boiler can be pumped to about 0Pa by the induced draft fan to pump the negative pressure of the circulating fluidized bed boiler feed port, so as to realize zero-pressure feeding at the feed port.

[0011] The present invention reduces the soil content in biomass fuel through sorting technology, and reduces the negative pressure at the furnace feed port to improve the combustion efficiency of the circulating fluidized bed boiler burning biomass, while ensuring that the pressure at the feed port of the circulating fluidized bed boiler is at a zero pressure point, ultimately avoiding the positive pressure in the circulating fluidized bed boiler causing the flue gas backflow of the feeding system, thereby greatly improving the economy and safety of the circulating fluidized bed boiler.

[0012] As a preferred embodiment of the present invention, a material leveling device is provided in the biomass feed port. The material leveling device can disperse the biomass fuel, and the biomass fuel is evenly dispersed on the sorting mobile feeding device through the buffer bin under the joint action of the material leveling device and the upward airflow coming out of the sorting mobile feeding device. When the biomass fuel is evenly dispersed, the upward airflow can more fully carry the dust in the biomass fuel to the upper part of the buffer bin to form a dusty airflow.

[0013] As a preferred solution of the present invention, a valve is connected to the pipeline between the blower and the sorting mobile feeding device. When the soil content of the biomass fuel is not high, the valve on the air duct between the blower and the sorting mobile feeding device is closed, and then the pressure at the feeding port of the circulating fluidized bed boiler can be pumped to near the zero pressure point by using the induced draft fan to draw a small negative pressure.

[0014] As a preferred embodiment of the present invention, the blower is also connected to the circulating fluidized bed through a pipeline. When the blower is a primary blower, a secondary blower or a high-pressure fluidizing blower for a circulating fluidized bed boiler, the blower also blows air into the circulating fluidized bed boiler.

[0015] As a preferred embodiment of the present invention, the top of the dust collector is connected to the induced draft fan through a pipeline, and a valve is provided on the pipeline between the dust collector and the induced draft fan. The dust collector directly uses the induced draft fan connected to the circulating fluidized bed boiler to extract the gas, and reasonably utilizes the existing induced draft fan system of the circulating fluidized bed boiler to achieve the pre-treatment of the biomass fuel, which greatly reduces the operation and transformation costs. When the soil content of the biomass fuel is not high, it is also necessary to close the valve on the pipeline between the dust collector and the induced draft fan.

[0016] As a preferred embodiment of the present invention, a dust collecting hopper is provided at the bottom of the dust collector, and dust settled in the dust collector can be collected in the dust collecting hopper for easy collection.

[0017] As a preferred solution of the present invention, a plurality of distribution pipes are arranged at the bottom of the sorting mobile feeding device, and the main pipe between the blower and the sorting mobile feeding device is connected to the plurality of distribution pipes. The plurality of distribution pipes can evenly deliver the airflow to various areas at the bottom of the sorting mobile feeding device, so as to facilitate more even distribution of the biomass fuel.

[0018] As a preferred embodiment of the present invention, the air blower is a separate blower or a primary blower of a circulating fluidized bed boiler, a secondary blower of a circulating fluidized bed boiler or a high-pressure fluidizing blower of a circulating fluidized bed boiler.

[0019] As a preferred solution of the present invention, the sorting type mobile feeding device is a mobile grate or a mobile chain plate conveyor. By supplying air to the lower part of the sorting type mobile feeding device, the biomass fuel can be sorted while the feeding is moving.

[0020] As a preferred embodiment of the present invention, the dust collector is a gravity settling dust collector or a cyclone dust collector.

[0021] The beneficial effects of the present invention are:

[0022] The present invention reduces the soil content in biomass fuel through sorting technology, and reduces the negative pressure at the furnace feed port to improve the combustion efficiency of the circulating fluidized bed boiler burning biomass, while ensuring that the pressure at the feed port of the circulating fluidized bed boiler is at a zero pressure point, ultimately avoiding the positive pressure in the circulating fluidized bed boiler causing the flue gas backflow of the feeding system, thereby greatly improving the economy and safety of the circulating fluidized bed boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the present invention.

[0024] In the figure: 1- biomass feed port; 2- buffer bin; 3- material equalization device; 4- sorting mobile feeding equipment; 5- circulating fluidized bed boiler feed port; 6- circulating fluidized bed boiler; 7- blower; 8- dust collector; 9- ash hopper; 10- induced draft fan. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0027] like Figure 1As shown, the feeding system of the sorting biomass-fired circulating fluidized bed boiler of this embodiment includes a circulating fluidized bed boiler 6 and a buffer bin 2, a circulating fluidized bed boiler feeding port 5 is connected between the circulating fluidized boiler and the buffer bin 2, a biomass feeding port 1 is connected to the buffer bin 2, a sorting mobile feeding device 4 is installed in the buffer bin 2, a blower 7 is connected to the bottom of the sorting mobile feeding device 4 through a pipeline, a dust collector 8 is connected to the upper part of the buffer bin 2 through a pipeline, and an ash hopper 9 is arranged at the bottom of the dust collector 8; the top of the circulating fluidized bed boiler 6 is connected to an induced draft fan 10 through a pipeline; and a material equalizing device 3 is arranged in the biomass feeding port 1.

[0028] When the soil content of biomass is high and the circulating fluidized bed boiler feed port 5 cannot be kept near the zero pressure point by controlling the negative pressure at the furnace outlet of the circulating fluidized bed boiler 6, the biomass fuel enters the buffer bin 2 from the biomass feed port 1 through the equalizing device 3. At the same time, the wind delivered by the blower 7 enters the sorting mobile feeding equipment 4. Under the joint action of the equalizing device 3 and the upward airflow coming out of the sorting mobile feeding equipment 4, the biomass fuel is evenly distributed on the sorting mobile feeding equipment 4 through the buffer bin 2; the top of the dust collector 8 is connected to the induced draft fan 10 through a pipeline.

[0029] The above-mentioned rising airflow carries the dust in the biomass fuel to the upper part of the buffer bin 2 to form a dust-containing airflow, and the dust-containing airflow enters the dust collector 8, and the dust collector 8 captures the dust in the airflow and enters the dust hopper, and the airflow after dust removal is sucked away by the induced draft fan 10. The biomass fuel after dust removal is sent to the circulating fluidized bed boiler feed port 5 by the forward-moving sorting mobile feeding device 4 to enter the furnace for combustion. After the dust in the biomass is removed, the ash concentration in the circulating fluidized bed boiler 6 is greatly reduced. At this time, the induced draft fan 10 is used to extract a lower negative pressure (lower than -1000Pa) from the furnace of the circulating fluidized bed boiler 6, so that the negative pressure at the circulating fluidized bed boiler feed port 5 can be pumped to about 0Pa, realizing zero-pressure feeding at the feed port.

[0030] A valve is connected to the pipeline between the blower 7 and the sorting mobile feeding device 4, and a valve is set on the pipeline between the dust collector 8 and the induced draft fan 10. When the soil content of the biomass is not high, the valve on the air duct between the blower 7 and the sorting mobile feeding device 4 is closed, and the valve on the pipeline between the dust collector 8 and the induced draft fan 10 is closed, and then the pressure at the circulating fluidized bed boiler feed port 5 can be pumped to near the zero pressure point by the induced draft fan 10 to draw a small negative pressure (lower than -1000Pa), and then the biomass enters the buffer bin 2 through the biomass feed port 1 through the equalizing device 3, and is evenly distributed on the sorting mobile feeding device 4, and is sent from the circulating fluidized bed boiler feed port 5 to the circulating fluidized bed boiler 6 for combustion by controlling the sorting mobile feeding device 4.

[0031] Furthermore, the blower 7 is also connected to the circulating fluidized bed through a pipeline; the blower 7 can be a separate blower or a primary blower, a secondary blower or a high-pressure fluidizing blower for the circulating fluidized bed boiler 6, and its function is to provide cold air with a certain pressure head to be sent to the sorting mobile feeding device 4 for sorting the biomass fuel. When the blower 7 is a primary blower, a secondary blower or a high-pressure fluidizing blower for the circulating fluidized bed boiler 6, the blower 7 also sends air into the circulating fluidized bed boiler 6.

[0032] Furthermore, a plurality of distribution pipes are provided at the bottom of the sorting mobile feeding device 4, and the main pipe between the blower 7 and the sorting mobile feeding device 4 is connected to the plurality of distribution pipes. The plurality of distribution pipes can evenly deliver the airflow to various areas at the bottom of the sorting mobile feeding device 4, so as to facilitate more even distribution of the biomass fuel.

[0033] The sorting mobile feeding device 4 may be a mobile grate or a mobile chain conveyor, etc., and its function is to achieve the sorting of biomass fuel while moving the feed through the lower air supply.

[0034] The dust collector 8 can be a gravity settling type, a cyclone type or the like, and its main function is to capture dust in the dust-laden airflow after biomass sorting.

[0035] The main function of the induced draft fan 10 is to achieve a circulating fluidized bed boiler feed port 5 near the zero pressure point under the condition of a small negative pressure (within -1000Pa) at the outlet of the circulating fluidized bed boiler 6, and to ensure that the pressure at the upper feed port of the biomass buffer bin 2 is negative pressure.

[0036] The outlet of the dust collector 8 can be connected to any position before the induced draft fan 10 of the flue gas system of the circulating fluidized bed boiler 6 .

[0037] The present invention reduces the soil content in biomass fuel through sorting technology, and reduces the negative pressure at the furnace feed port to improve the combustion efficiency of the biomass circulating fluidized bed boiler 6 while ensuring that the pressure at the feed port 5 of the circulating fluidized bed boiler is at a zero pressure point, ultimately avoiding the positive pressure in the circulating fluidized bed boiler 6 causing the flue gas backflow of the feeding system, thereby greatly improving the economy and safety of the circulating fluidized bed boiler 6.

[0038] The system process of the present invention is based on relevant theoretical research. The biomass fuel and dust are separated by pneumatic separation technology, and after the negative pressure of the furnace is controlled, the biomass fuel is sent to the circulating fluidized bed boiler feed port 5 where the pressure is near the zero pressure point, and then enters the circulating fluidized bed boiler 6 for stable combustion. The feeding system has a simple process structure and a simple control method. It can achieve zero pressure at the circulating fluidized bed boiler feed port 5, solve the impact of the positive pressure backflow of the circulating fluidized bed boiler 6 on the safety of the feeding system, and at the same time reduce the soil content in the biomass fuel, increase the operating temperature level in the furnace, reduce the heat loss caused by ash discharge, and finally achieve economical and safe operation of the circulating fluidized bed boiler 6.

[0039] The dust collector 8 of the present invention directly uses the induced draft fan 10 connected to the circulating fluidized bed boiler 6 to extract the gas, rationally utilizes the existing induced draft fan 10 system of the circulating fluidized bed boiler 6, realizes the pretreatment of the biomass fuel, and greatly reduces the operation and transformation costs.

[0040] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A sorting type biomass-fired circulating fluidized bed boiler feeding system, characterized in that: The invention comprises a circulating fluidized bed boiler (6) and a buffer bin (2), wherein a circulating fluidized bed boiler feed port (5) is connected between the circulating fluidized bed boiler and the buffer bin (2), a biomass feed port (1) is connected to the buffer bin (2), a sorting type mobile feeding device (4) is installed in the buffer bin (2), a blower (7) is connected to the bottom of the sorting type mobile feeding device (4) via a pipeline, and a dust collector (8) is connected to the top of the buffer bin (2) via a pipeline; an induced draft fan (10) is connected to the top of the circulating fluidized bed boiler (6) via a pipeline; and the top of the dust collector (8) is connected to the induced draft fan (10) via a pipeline.

2. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: A material equalization device (3) is provided in the biomass feed port (1).

3. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: A valve is connected to the pipeline between the air blower (7) and the sorting mobile feeding device (4).

4. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: The air blower (7) is also connected to the circulating fluidized bed via a pipeline.

5. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: A dust collecting hopper (9) is provided at the bottom of the dust collector (8).

6. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: A plurality of distribution pipes are arranged at the bottom of the sorting type mobile feeding device (4), and the main pipe between the blower (7) and the sorting type mobile feeding device (4) is connected to the plurality of distribution pipes.

7. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: The air supply fan (7) is a separate fan or a primary fan of a circulating fluidized bed boiler (6), a secondary fan of a circulating fluidized bed boiler (6), or a high-pressure fluidizing fan of a circulating fluidized bed boiler (6).

8. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1 is characterized in that: The sorting type mobile feeding device (4) is a mobile grate or a mobile chain conveyor.

9. The feeding system of a sorting biomass-fired circulating fluidized bed boiler according to claim 1, characterized in that: The dust collector (8) is a gravity settling type dust collector (8) or a cyclone type dust collector (8).

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