CN205261533U - Boiler combustion system - Google Patents

Abstract

The utility model discloses a boiler combustion system, comprising: a boiler, a burner and a biomass gasification device. Boilers include combustion chambers and flue gas ducts. The burner is arranged on one end wall of the boiler for injecting fuel into the combustion chamber for burning and releasing heat. The biomass gasification device sends the generated biomass gas to the burner for combustion through the gas pipeline. Wherein, the burner includes a housing, a biomass gas inlet provided on one end wall of the housing, a flame outlet provided at the other end of the housing, a gas nozzle extending from the biomass gas inlet to the inside of the housing, and a gas nozzle provided on the side of the housing. At least one air inlet on the wall, the end of the gas nozzle is closed, and several sub-nozzles are arranged at intervals on the peripheral wall of the gas nozzle, and the biomass gas is injected into the interior of the shell through several sub-nozzles and combined with the combustion-supporting gas from at least one air inlet. Air mixes and burns.

Description

Boiler combustion system

technical field

The utility model relates to a boiler combustion system, in particular to a boiler combustion system using biomass gas.

Background technique

As we all know, coal, oil, natural gas and other fossil energy resources are non-renewable resources, which have been gradually exhausted under the large-scale exploitation of human beings. In addition, these fuels will emit a large amount of toxic and harmful gases into the air when they are burned, causing serious air pollution. To this end, experts in the energy field are working hard to find renewable and clean fuels to replace fossil energy.

Biomass fuel (BMF for short, such as agricultural and forestry waste, such as straw, sawdust, bagasse, rice bran, etc.) has the following characteristics: 1. The energy of BMF comes from the absorption of CO ₂ in nature during its growth, so BMF has CO _2. The characteristics of ecological "zero"emission; 2. The combustion of BMF is mainly volatile matter, and its fixed carbon content is about 15%, which is a typical low-carbon fuel; 3. The sulfur content of BMF is lower than that of diesel, only 0.05%, the emission of SO ₂ can be realized without installing a desulfurization device; 4. The ash content of BMF is only 1.8%, which is about 1/10 of coal-based fuel, and the dust emission can reach the standard with a simple dust removal device; 5. BMF has low nitrogen content and high oxygen content, and generates less _NOx during combustion; 6. BMF comes from agricultural and forestry waste, with wide and diverse distribution of raw materials, low cost, cyclic growth, and inexhaustible supply. It is a typical circular economy project.

Biomass gasification uses biomass as raw material. Under the action of gasification agent, oxygen (air, oxygen-enriched or pure oxygen), water vapor or hydrogen is usually used as gasification agent (also called gasification substance). The process of converting the combustible part of biomass into combustible gas through thermochemical reaction under high temperature conditions. The gas components produced during biomass gasification mainly include H ₂ , CH ₄ and CO, etc., and this combustible gas is usually called biomass gas.

However, biomass gas has low calorific value and high tar content. If it is directly supplied to boiler equipment as fuel like natural gas or coal gas, the combustion efficiency will be low on the one hand, and it may bring safety hazards on the other hand.

As disclosed in Chinese Patent Application Publication No. 102954456A, an energy-saving device for carbon production includes a gasifier, a combustion chamber and a boiler device. The combustion chamber communicates with the gasifier and is located in the boiler device, and the boiler device is also Including the upper pot, the lower pot and the water-cooled wall pipe between the upper pot and the lower pot, because biomass gas is used as fuel, it reduces the cost by 40% compared with direct use of natural gas, and reduces the cost by 150% compared with oil. However, the energy-saving device for carbon production has the following disadvantages or deficiencies: (1), the waste heat of the gasification furnace body is not fully utilized; (2), the biomass gas is used as gas without any filtration and purification, This will bring safety hazards to the boiler device; (3), the burner has not been improved for biomass gas, and the combustion efficiency is low.

Another example is a biomass gasification combustion boiler system disclosed in Chinese Patent Application Publication No. 103499083A, which includes a boiler and a biomass gasifier for providing gasification fuel for the boiler. The biomass gasifier passes through the gas pipeline and the boiler Connection, the upper part of the biomass gasification furnace is provided with a feed port, and the interior of the biomass gasification furnace is a gas storage chamber, a reaction chamber, and an ash storage hopper in sequence from top to bottom, and a heating furnace is installed between the reaction chamber and the ash storage hopper row, and the feed port communicates with the reaction chamber through a feed pipeline. However, the biomass gasification combustion boiler system has the following shortcomings or deficiencies: (1), the waste heat of the gasification furnace body is not fully utilized; (2), the complex cyclone separator and water film decoker are used to Biomass gas is purified, which increases the construction cost of the system; (3) The burner has not been improved for biomass gas, and the combustion efficiency is low.

Therefore, it is an urgent problem in the industry to provide a boiler combustion system using biomass gas that can fully improve energy utilization and combustion efficiency.

Contents of the invention

The purpose of the utility model is to provide a boiler combustion system, which can significantly improve the utilization rate of biomass energy and improve the combustion efficiency and safety of the boiler.

Compared with other biomass utilization technologies, biomass gasification technology is a widely used biomass energy conversion method. The gasification process of biomass is mainly carried out in the gasification furnace. Due to the different types of gasification furnaces, gasification reaction conditions, process flow, types of gasification agents, properties of raw materials and crushing particle size, the gasification reaction The process is also different. However, the biomass gasification process under different conditions basically includes: C+O ₂ =CO ₂ ; CO ₂ +C=2CO; H ₂ O+C=CO+H ₂ and so on.

Generally speaking, the actual reaction process of biomass mainly includes four parts: (1) Drying layer, in which the biomass enters the gasifier from the top of the gasifier, and after being heated to about 200-300°C, the biomass raw material The moisture in the biomass is first heated and evaporated, and the final product is dry material; (2), the pyrolysis layer, in which the dry biomass material moves down from the dry layer into the pyrolysis layer, and under the action of high temperature, a large amount of volatile matter in the biomass will The action temperature is around 500-600°C. After volatile analysis, only residual charcoal remains in the biomass. The volatiles precipitated from thermal decomposition mainly include hydrogen, carbon monoxide, carbon dioxide, methane, tar and other hydrocarbons. Compounds, etc.; (3) Oxidation layer (also called combustion layer), in which only charcoal remains after the biomass is pyrolyzed. At this time, it reacts violently with the introduced air in the oxidation layer and releases a large amount of heat at the same time. , to provide heat for the reaction in other areas. In the oxide layer, it is characterized by fast reaction rate, low layer height, and the temperature can be as high as 1000-1200 ° C. At the same time, volatile matter participates in combustion and further degrades; (4), reduction layer , there is no oxygen in the reduction layer, the combustion products and water vapor in the oxidation layer undergo a reduction reaction with the charcoal in the reduction layer, biohydrogen and carbon monoxide, these gases and volatile matter form combustible gases, and complete the conversion of solid biomass to gas fuel In the conversion process, since the reduction reaction is an endothermic reaction, the temperature at this time drops to about 700-900 ° C, and the heat required mainly comes from the oxide layer.

The biomass gasification reaction is mainly carried out in the gasifier. Take the above-suction fixed-bed gasifier as an example. Reaction, the gas generated by the reaction flows from bottom to top, and finally is discharged from the gas outlet on the upper part of the gasifier. Among them, the reaction process of biomass includes drying layer, pyrolysis layer, reduction layer and oxidation layer in sequence from top to bottom. Its main advantages are: when the gas passes through the thermal decomposition zone and the drying zone, it transfers the heat it carries to the biomass raw material, which is used for drying and thermal decomposition of the raw material, while reducing the temperature of the gas and improving the thermal efficiency of the gasifier ; Since the biomass raw material is added from the upper part of the furnace, the biogas passes through the material layer when it comes out from the upper part, which has a certain filtering effect on the gas and reduces the ash content in the biogas.

According to an aspect of the present utility model, a boiler combustion system is provided, including: a boiler, a burner, and a biomass gasification device. The boiler includes a combustion chamber and a flue gas pipe communicating with the combustion chamber. The burner is arranged on one end wall of the boiler for injecting fuel into the combustion chamber for burning and releasing heat. The biomass gasification device sends the generated biomass gas to the burner for combustion through the gas pipeline. The biomass gasification device includes a device body, a biomass feed port located on the top wall of the device body, at least one biomass gas outlet located on the side wall of the device body adjacent to the top wall of the device body, located inside the device body and The interior of the device body is divided into the gasification reaction chamber located in the upper middle part and the fire grate located in the lower part of the air chamber, the heat exchange chamber arranged around the outer wall of the device body and located outside the gasification reaction chamber, and the heat exchange chamber located in the heat exchange chamber hot air and hot water pipes. Wherein, at least one biomass gas outlet communicates with the heat exchange chamber so that: the high-temperature biomass gas heats the cold air in the hot air pipe into hot air and transports it to the air chamber as a gasification agent, and heats the cold water in the hot water pipe into hot air. The water vapor is sent to the air chamber as a gasifying agent.

Wherein, at least one biomass gas outlet connects the interior of the device body with the interior of the heat exchange chamber, and the heat exchange chamber includes a medium-temperature gas outlet located at the bottom, and the hot air pipe and the hot water pipe connect at least one biomass gas outlet. One up and one down between the middle temperature gas outlet and the heat exchange chamber.

Wherein, the hot air pipe is a coil pipe arranged in the heat exchange chamber around the outside of the device body, the upper port of the hot air pipe is connected to the first fan, and the lower port of the hot air pipe is connected to the air chamber through a pipeline.

Wherein, the hot water pipe is a coil pipe arranged in the heat exchange chamber around the outside of the device body, the upper port of the hot water pipe is connected to the water pump, and the lower port of the hot water pipe is connected to the air chamber through a pipeline.

Optionally, the gas sent by the first blower to the hot air pipe is air at 20-25 degrees Celsius, and the water pumped into the hot water pipe is cold water at 20-30 degrees Celsius.

Optionally, an ash outlet is provided on the lower side of the gasification reaction chamber of the biomass gasification device.

Optionally, the medium-temperature gas outlet is arranged on the lower end wall of the heat exchange chamber.

Optionally, the boiler combustion system further includes a screw feeder, the feed port of the screw feeder is connected to the biomass source, and the discharge port of the screw feeder communicates with the biomass feed port of the device body to transport the biomass to The gasification reaction is carried out in the gasification reaction chamber. The screw feeder includes a vertical section and a horizontal section connected with the vertical section.

Optionally, the vertical section of the screw feeder includes a medium-temperature gas inlet adjacent to the feed inlet and a low-temperature gas outlet adjacent to the connection between the vertical section and the horizontal section, and the medium-temperature gas inlet passes through the pipeline and the medium-temperature gas in the heat exchange chamber The outlet is connected to introduce biomass gas into the screw feeder to preheat the biomass and remove dust and tar, and the biomass gas is delivered to the burner through the gas pipeline through the low-temperature gas outlet for combustion.

Optionally, the burner includes a housing, a biomass gas inlet provided on one end wall of the housing, a flame outlet provided at the other end of the housing, a gas nozzle extending from the biomass gas inlet to the inside of the housing, and a gas nozzle provided on the housing. At least one air inlet on the body side wall.

Optionally, the end of the gas nozzle is closed, and several sub-nozzles are arranged at intervals on the peripheral wall of the gas nozzle, and the biomass gas is injected into the housing through several sub-nozzles and mixed with the combustion-supporting air from at least one air inlet for combustion .

Preferably, the peripheral wall of the gas nozzle includes at least three groups of sub-nozzles arranged at equal intervals on different cross-sections of the gas nozzle, and each group of sub-nozzles includes at least three groups of sub-nozzles arranged at equal intervals along the circumferential direction on the side wall of the gas nozzle. At least three sub-nozzles.

Optionally, at least one air inlet of the burner is arranged adjacent to one end wall of the casing, the burner further includes at least one return flue gas inlet arranged on the side wall of the casing adjacent to the other end of the casing, and the flue gas duct of the boiler A return flue gas outlet is provided, and the return flue gas outlet communicates with at least one return flue gas inlet through the flue gas return pipeline, so as to return part of the high-temperature flue gas from the boiler to the burner for combustion.

Wherein, at least one air inlet included in the burner is arranged on the side wall of the casing along the tangential direction so that the air forms a swirling flow in the casing to enhance the mixing with the biomass gas, and at least one return flue gas inlet is arranged on the side wall along the tangential direction The side wall of the casing makes the flue gas form a swirl in the casing to enhance the mixing with the biomass gas and air.

Optionally, the side wall of the burner housing includes three air inlets arranged at equal intervals along the circumferential direction, and the side wall of the burner housing includes three air inlets arranged at equal intervals along the circumferential direction. A return flue gas inlet.

Preferably, in the longitudinal direction of the burner, at least three groups of sub-nozzles are located between at least one air inlet and at least one return flue gas inlet.

Optionally, a third fan is arranged in the gas pipeline, and a fourth fan is arranged in the flue gas return pipeline.

Wherein, the high temperature, medium temperature and low temperature in the present invention only indicate the relative temperature changes of gas, air or flue gas, and do not represent specific temperature values or ranges.

The beneficial effects of the utility model are: (1), make full use of the high temperature of the furnace wall of the biomass gasification device and the high temperature of the biomass gas to preheat air and water, and directly supply the obtained hot air and water vapor to the air chamber as Gasification agent, saving energy and cost; (2) Biomass gas enters the screw feeder, on the one hand, it preheats the biomass to improve the gasification efficiency; on the other hand, it filters the gas through the biomass to remove ash In addition to tar, it saves the cost of building a special filter and purification device; (3), the burner adopts high-temperature flue gas backflow to support combustion, which significantly improves the combustion efficiency and reduces the content of nitrogen oxides and carbon dioxide in the flue gas emitted by the boiler; (4) ), the biomass gas is filtered and purified by the screw feeder and then enters the burner for use, so as to avoid potential safety hazards caused by long-term use of the biomass gas due to the high tar content of the biomass gas.

Description of drawings

Fig. 1 shows a schematic structural view of the boiler combustion system of the present invention.

Fig. 2 shows a schematic structural view of the burner used in the present invention.

Fig. 3 shows a schematic cross-sectional view of the burner used in the present invention.

detailed description

Please refer to FIG. 1 , according to an embodiment of the present utility model, a boiler combustion system includes: a boiler 100 , a burner 200 and a biomass gasification device 300 .

The boiler 100 includes a combustion chamber (not shown in the figure) and a flue gas pipe 120 communicating with the combustion chamber. The burner 200 is disposed on an end wall 111 of the boiler 100 for injecting fuel into the combustion chamber for burning and releasing heat. The biomass gasification device 300 delivers the generated biomass gas to the burner 200 for combustion through a gas pipeline (not labeled).

The biomass gasification device 300 includes a device body 310, a biomass feed port 312 arranged on the top wall of the device body 310, and several biomass gas outlets arranged on the side wall of the device body 310 adjacent to the top wall of the device body 310 313. Set inside the device body 310 and divide the inside of the device body 310 into the gasification reaction chamber 320 located in the upper middle and the air chamber 330 located in the lower part. (not shown), a heat exchange chamber 350 disposed around the outer wall of the device body 310 and located outside the gasification reaction chamber 320 , and a hot air pipe 360 and a hot water pipe 370 disposed in the heat exchange chamber 350 . Wherein, the two biomass gas outlets 313 communicate with the heat exchange chamber 350 so that: the high-temperature biomass gas heats the cold air in the hot air pipe 360 into hot air and transports it to the air chamber 330 as a gasification agent, and The cold water in the hot water pipe 370 is heated into water vapor and transported into the air chamber 330 as a gasifying agent.

The biomass gas outlet 313 communicates the interior of the device body 310 with the interior of the heat exchange chamber 350, and the heat exchange chamber 350 includes a medium-temperature gas outlet 351 located on the lower end wall of the heat exchange chamber 350, a hot air pipe 360 and a heat exchange chamber 350. The water pipes 370 are arranged in the heat exchange chamber 350 one above the other between the two biomass gas outlets 313 and the medium temperature gas outlet 351 .

In this non-limiting embodiment, the hot air pipe 360 is a coil pipe arranged in the heat exchange chamber 350 around the outside of the device body 310, the upper port 361 of the hot air pipe 360 is connected with the first fan 362, and the hot air pipe The lower port 363 of 360 is connected to the air chamber 330 through a pipeline, and the gas sent into the hot air pipe 360 by the first fan 362 is air at about 20 degrees Celsius.

In this non-limiting embodiment, the hot water pipe 370 is a coil pipe arranged in the heat exchange chamber 350 around the outside of the device body 310, the upper port 371 of the hot water pipe 370 is connected with the water pump 372, and the hot water pipe 370 The lower port 373 is connected to the air chamber 330 through a pipeline, and the water sent into the hot water pipe 370 by the water pump 372 is cold water at about 20 degrees Celsius.

As a non-limiting embodiment, the boiler combustion system also includes a screw feeder 400, the feed port 410 of the screw feeder 400 is connected to a biomass source (not shown), and the discharge port 420 of the screw feeder 400 is connected to The biomass feed port 312 of the device body 310 is connected to transport the biomass to the gasification reaction chamber 320 for gasification reaction. The screw feeder 400 includes a vertical section 430 and a horizontal section 440 connected to the vertical section 430. The material opening 410 is located at the end of the vertical section 430 , and the material outlet 420 is located at the end of the horizontal section 440 .

In this non-limiting embodiment, the vertical section 430 of the screw feeder 400 includes a medium-temperature gas inlet 450 disposed adjacent to the feed port 410 and a low-temperature gas outlet 460 adjacent to the junction of the vertical section 430 and the horizontal section 440. The gas inlet 450 communicates with the medium-temperature gas outlet 351 of the heat exchange chamber 350 through a pipeline to introduce the biomass gas into the screw feeder 400 to preheat the biomass and remove dust and tar, and the biomass gas passes through the gas pipeline through the low-temperature gas outlet 460 ( (unnumbered) is delivered to the burner 200 for combustion, and a third blower 500 is arranged in the gas pipeline.

Fig. 2 is a schematic structural view of the burner 200, and Fig. 3 is a schematic cross-sectional view of the burner 200, as shown in Fig. 2 and Fig. The inlet 212, the flame outlet 214 at the other end of the housing, the gas nozzle 220 extending from the biomass gas inlet 212 to the inside of the housing 210, and the air inlet 230 arranged on the side wall of the housing, the air inlet 230 is adjacent to the housing An end wall 211 of 210 is arranged on the side wall of the housing along the tangential direction so that the air forms a swirling flow in the housing 210 to enhance mixing with the biomass gas, and the air inlet 230 is connected to the second blower 250 .

The burner 200 also includes a return flue gas inlet 240 disposed on the side wall of the housing adjacent to the other end of the housing 210, and the return flue gas inlet 240 is arranged on the side wall of the housing along a tangential direction so that the flue gas flows in the housing 210. Swirls are created to enhance mixing with biomass gas and air. The flue gas pipe 120 of the boiler 100 is provided with a backflow flue gas outlet 121, and the backflow flue gas outlet 121 communicates with the backflow flue gas inlet 240 through a flue gas return pipeline (unlabeled) to return part of the high-temperature flue gas from the boiler 100 to the combustion chamber. The device 200 supports combustion, and the fourth fan 600 is arranged in the flue gas return pipeline.

In this non-limiting embodiment, the end of the gas nozzle 220 is closed, and three groups of sub-nozzles 221 are arranged at intervals on the peripheral wall of the gas nozzle 220. There are three sub-nozzles 221 on the side wall of the pipe 220 , and the biomass gas is injected into the housing 210 through the three groups of sub-nozzles 221 and mixed with the combustion air from the air inlet 230 for combustion.

In this non-limiting embodiment, in the longitudinal direction of the burner 200 , three groups of sub-nozzles 221 are located between the air inlet 230 and the return flue gas inlet 240 .

According to the boiler combustion system provided by the utility model, the biomass fuel is transported to the gasification reaction chamber 320 through the biomass feed port 312 of the device body 310 via the screw feeder 400 for gasification reaction to generate high-temperature biomass gas. Biomass gas heats the cold air in the hot air pipe 360 into hot air and transports it to the air chamber 330 as a gasification agent, and heats the cold water in the hot water pipe 370 into water vapor and then transports it to the air chamber 330 as a gasifying agent. agent. After exchanging heat with the cold air in the hot air pipe 360 and the cold water in the hot water pipe 370, the biomass gas enters the screw feeder 400 through the pipeline to preheat the biomass, remove dust and tar, and then transport it through the gas pipeline through the low-temperature gas outlet 460 After the burner 200 is mixed with the air from the air inlet 230, it is injected into the combustion chamber of the boiler 100 to burn and release heat, and part of the flue gas generated by the combustion in the combustion chamber is returned to the burner 200 for combustion support through the flue gas return pipeline.

Although the preferred embodiment of the present utility model has been described in detail here, it should be understood that the present utility model is not limited to the specific structures described and shown in detail here, and can be made by Other modifications and variations will occur to those skilled in the art. For example, a waste heat boiler is installed on the flue gas pipe of the boiler to further utilize the waste heat of the flue gas, or other feeding methods are used to replace the screw feeder feeding, or the number of sub-nozzles arranged at intervals on the surrounding wall of the gas nozzle is adjusted according to specific service conditions. In addition, the temperature, pressure and other parameters of various parts of the system can be properly selected according to specific conditions of use.

Claims (8)

1. A boiler combustion system, comprising: A boiler comprising a combustion chamber and a flue gas duct communicating with the combustion chamber; a burner provided on one end wall of the boiler; and A biomass gasification device, the biomass gasification device is connected to the burner through a gas pipeline; It is characterized by: The biomass gasification device includes a device body, a biomass feed port arranged on the top wall of the device body, and at least one biomass gas provided on the side wall of the device body adjacent to the top wall of the device body The outlet, the fire grate arranged inside the device body and dividing the inside of the device body into a gasification reaction chamber located in the upper middle and a wind chamber located in the lower part, is arranged around the outer wall of the device body and is located in the gasification A heat exchange chamber outside the reaction chamber, and a hot air pipe and a hot water pipe arranged in the heat exchange chamber, wherein the at least one biomass gas outlet communicates with the heat exchange chamber; and The burner includes a housing, a biomass gas inlet provided at one end wall of the housing, a flame outlet provided at the other end of the housing, and a gas outlet extending from the biomass gas inlet to the inside of the housing. A nozzle, and at least one air inlet provided on the side wall of the casing, the end of the gas nozzle is closed, and several sub nozzles are arranged at intervals on the peripheral wall of the gas nozzle. 2. The boiler combustion system according to claim 1, wherein the at least one biomass gas outlet connects the interior of the device body with the interior of the heat exchange chamber, and the heat exchange chamber It includes a medium-temperature gas outlet arranged at the bottom, and the hot air pipe and the hot water pipe are arranged one above the other in the heat exchange chamber between the at least one biomass gas outlet and the medium-temperature gas outlet. 3. The boiler combustion system according to claim 2, wherein the hot air pipe is a coil pipe arranged in the heat exchange chamber around the outside of the device body, and the upper port of the hot air pipe Connected with the first fan, the lower port of the hot air pipe is connected to the air chamber through a pipeline. 4. The boiler combustion system according to claim 2, wherein the hot water pipe is a coil pipe arranged in the heat exchange chamber around the outside of the device body, and the upper port of the hot water pipe It is connected with the water pump, and the lower port of the hot water pipe is connected to the air chamber through a pipeline. 5. The boiler combustion system according to claim 2, further comprising a screw feeder, the feed port of the screw feeder is connected to the biomass source, and the discharge port of the screw feeder is connected to the The biomass feed port of the device body is connected, the screw feeder includes a vertical section and a horizontal section connected to the vertical section, the feed port is arranged at the end of the vertical section, and the A discharge port is provided at the end of the transverse section. 6. The boiler combustion system according to claim 5, characterized in that, the vertical section of the screw feeder includes a medium-temperature gas inlet adjacent to the feed inlet and adjacent to the vertical section and the The low-temperature gas outlet at the junction of the transverse section, the medium-temperature gas inlet communicates with the medium-temperature gas outlet of the heat exchange chamber through a pipeline, and the low-temperature gas outlet is connected to the burner through a gas pipeline. 7. The boiler combustion system according to claim 6, wherein said at least one air inlet is disposed adjacent to said one end wall of said housing, said burner further comprising a There is at least one return flue gas inlet on the side wall of the housing, and a return flue gas outlet is provided on the flue gas pipe of the boiler, and the return flue gas outlet is connected to the at least one return flue gas through the flue gas return pipeline. The gas inlet is connected. 8. The boiler combustion system according to claim 7, wherein the at least one air inlet is arranged on the side wall of the housing along a tangential direction, and the at least one return flue gas inlet is arranged along a tangential direction on the housing sidewall.