CN105841140A - Biomass gasification product and coal co-firing system and method - Google Patents

Abstract

The invention discloses a system and method for co-combustion of biomass gasification products and coal. The system includes a biomass gasification device, a biomass gasification product separation and delivery device, and a boiler co-combustion device. Substances are used as raw materials, and the biomass raw materials are used to obtain biomass gasification products. The biomass gasification products include biomass coke and gaseous products; the biomass gasification product separation and conveying device is used to separate and transport the biomass gasification products to Co-combustion with coal in the boiler co-combustion device; the boiler co-combustion device is used to co-combust the biomass gasification product obtained in the biomass gasification device and coal in the boiler; the method uses the system to realize the biomass gasification product Co-combustion with coal. The invention separates the solid, gas and liquid products obtained from biomass gasification, fully utilizes all the products obtained from the gasification of biomass raw materials, improves the power generation efficiency of conventional biomass and coal co-firing boilers, and reduces pollutants and greenhouse gas emissions.

Description

A system and method for co-combustion of biomass gasification products and coal

technical field

The invention belongs to the technical field of energy utilization, and more specifically relates to a system and method for co-combusting biomass gasification products and coal.

Background technique

The extensive adoption of coal-fired power generation leads to the annual emission of a large amount of sulfur dioxide, nitrogen oxides and carbon dioxide gas. The loss caused by the emission of these pollutants and the acid rain formed by them accounts for about 8% of the total GDP, and the large emission of carbon dioxide has caused The severe greenhouse effect has led to an increase in global temperature and more frequent extreme weather. Therefore, it is urgent to speed up the adjustment of energy structure and reduce the consumption of coal.

China is a large agricultural country, with a huge output of agricultural and forestry waste every year. A large amount of agricultural straw is treated by field incineration, which produces a large amount of PM2.5 particles and causes a lot of waste of resources. Compared with fossil energy, biomass has the characteristics of abundant resources, low pollution, low ash and renewable. Combusting biomass to generate electricity can significantly reduce the emission of sulfur dioxide, nitrogen oxides, heavy metals and carbon dioxide.

Retrofitting existing coal-fired boilers and blending biomass can significantly reduce pollutant emissions, and has obvious advantages in terms of power generation scale, combustion efficiency and stable operation. However, due to the wide variety of biomass and different physical and chemical properties, the common co-combustion method has poor adaptability to fuels, and it is difficult to transport and pre-treat biomass, so there are still problems in the large-scale promotion of co-combustion technology.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a system and method for co-combustion of biomass gasification products and coal, which uses the low-nitrogen combustion technology of co-combustion of biomass gasification products and coal to convert each Biomass raw materials are pyrolyzed and gasified to produce three products: biomass coke, bio-oil, and gasification gas, which can convert biomass with large differences in properties into gasification products with relatively uniform properties, effectively solving the problem of boilers At the same time, the biomass particles are converted into gas, liquid and solid three-state products, which are respectively put into the boiler for co-combustion, which significantly improves the utilization efficiency and co-combustion effect of biomass, and makes full use of the combustion characteristics of gasification products. The content of nitrogen oxides in the flue gas is reduced, and the purpose of improving the adaptability of boiler raw materials and reducing pollutant emissions is achieved.

In order to achieve the above object, according to one aspect of the present invention, the present invention proposes a system for co-combustion of biomass gasification products and coal, which is characterized in that the system includes a biomass gasification device, a biomass gasification product separation and transportation Plant and boiler co-firing plant, where:

The biomass gasification device uses biomass as a raw material, and uses the biomass raw material to obtain biomass gasification products, and the biomass gasification products include biomass coke and gaseous products;

The biomass gasification product separation and conveying device is used to separate and transport the biomass gasification product to the boiler co-combustion device for co-combustion with coal;

The boiler co-combustion device is used for co-combusting the biomass gasification product obtained in the biomass gasification device and coal in the boiler.

As a further preference, the biomass gasification device includes a biomass feeder and a gasification reactor, the biomass feeder is connected to the gasification reactor, and is used to transport biomass raw materials to the gasification reactor Middle; the gasification reactor is used as a container for the gasification reaction of biomass raw materials, and its bottom is connected to the tail of the boiler in the boiler co-combustion device, so as to directly use the high-temperature flue gas at the tail of the boiler to provide gasification reaction for the gasification reactor. Energy required, O ₂ and CO ₂ .

As a further preference, the gasification reaction furnace is connected to the boiler in the boiler co-combustion device through a high-temperature flue gas pipeline, and a fan is installed on the high-temperature flue gas pipeline to facilitate the extraction of high-temperature flue gas from the boiler.

As a further preference, the boiler co-combustion device includes a boiler and a chimney connected to the tail of the boiler.

As a further preference, the biomass gasification product separation and delivery device includes a gas-solid separator, a bio-oil liquefaction separator and a coal mill, and the gas-solid separator separates the gaseous product leaving the gasification reactor to obtain a solid Granules, the solid particles are mixed with biomass coke and coal, and after being ground by a coal mill, they are sprayed into the furnace of the boiler for co-combustion, so as to use the heterogeneous reduction characteristics of biomass coke to reduce the nitrogen oxides produced during the combustion of pulverized coal substances, thereby reducing the emission of nitrogen oxides in the flue gas; the bio-oil liquefaction separator condenses the separated gaseous products to obtain bio-oil and gasification gas, and the bio-oil is collected in the bio-oil collector.

As a further preference, the gasified gas is sprayed into the reburning zone in the middle of the boiler furnace as a reburning fuel to form a reduction zone to reduce the nitrogen oxides generated by coal combustion into N ₂ , thereby reducing the generation of nitrogen oxides and reducing combustion The content of nitrogen oxides in flue gas.

As a further preference, the bio-oil is sprayed into the reburning zone in the middle of the boiler furnace as a reburning fuel to form a reduction zone to reduce the nitrogen oxides formed by coal combustion into N ₂ , thereby reducing boiler NO _X emissions; or The bio-oil is passed into the primary tuyere of the boiler as the ignition oil of the boiler; or the bio-oil is passed into the primary and secondary tuyere of the boiler as the oil for stable combustion of the boiler, thereby realizing the high efficiency of biomass energy Cascade utilization.

As a further preference, the temperature of the high-temperature flue gas is 100°C to 1200°C, and the composition is 5% O ₂ , 14% CO ₂ , 15% H ₂ O, 65.8% nitrogen and 0.2% nitrogen oxides and sulfur oxide.

According to another aspect of the present invention, there is provided a method for co-combustion of biomass gasification products and coal, characterized in that it comprises the following steps:

S1. Using a biomass gasification device to obtain biomass gasification products using biomass as raw material, the biomass gasification products include biomass coke and gaseous products;

S2. Using the biomass gasification product separation and delivery device to separate the biomass gasification product and transport it to the boiler co-combustion device;

S3. Using the boiler co-combustion device to co-combust the biomass gasification product obtained in the biomass gasification device and coal in the boiler.

As a further preference, step S1 includes the following sub-steps:

S11, open the high-temperature flue gas pipeline connecting the biomass gasification device and the boiler co-combustion device, and transport the energy, _O2 and _CO2 required for the gasification reaction to the biomass gasification device;

S12. The biomass raw material is continuously transported to the biomass gasification device through the biomass feeder, and quickly gasified to obtain biomass coke and gaseous products;

Step S2 includes the following sub-steps:

S21. Separating the solid particles in the gaseous products, collecting the solid particles, and separating the biomass coke in the biomass gasification device, mixing the solid particles and the biomass coke with coal, and then transporting them to the boiler for co-combustion Device co-combustion;

S22. Condensate and separate the separated gaseous products to obtain bio-oil and gasification gas, and transport the bio-oil and gasification gas to the boiler co-combustion device respectively.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. The system of the present invention performs gasification treatment on biomass raw materials before co-combustion to obtain three gasification products: gas, solid and liquid. The co-combustion method is put into the boiler and co-combusted with coal to convert different biomass with large differences in characteristics into three-state products with small differences, making full use of all products obtained from the gasification of biomass raw materials to achieve efficient use of biomass Matter energy, improve the power generation efficiency of conventional biomass and coal co-fired boilers, improve the adaptability of boilers to biomass, reduce the use of coal, reduce pollutants and greenhouse gas emissions, and ultimately achieve the purpose of protecting the environment and reducing carbon emissions .

2. In the present invention, changing the reaction conditions in the gasification reaction furnace will basically not have a significant impact on the subsequent co-combustion. When using different biomass raw materials, there is no need to modify the boiler, only the gasification reaction conditions need to be modified , which effectively solves the problem of the limitation of the boiler's adaptability to raw materials.

3. In the present invention, gasification gas and bio-oil are sprayed into the reburning zone to provide a reducing atmosphere and reduce the formation of nitrogen oxides. At the same time, the nitrogen content of the biomass itself is low, which can effectively reduce the nitrogen oxides in the combustion flue gas content.

4. In the present invention, bio-oil is used instead of diesel oil and heavy oil as boiler ignition and stable combustion oil to realize high-efficiency cascade utilization of biomass energy; in addition, for pulverized coal boilers, biomass with different shapes and not suitable for grinding It is difficult to transport directly into the pulverized coal furnace. The present invention adopts a fixed-bed gasification furnace, which can directly transport the chopped materials to the gasification furnace, which solves the problem of material feeding.

Description of drawings

Fig. 1 is a schematic structural diagram of a co-combustion system of biomass gasification products and coal according to an embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

As shown in Figure 1, a biomass gasification product and coal co-combustion system provided by an embodiment of the present invention mainly includes a biomass gasification device A, a biomass gasification product separation and delivery device B, and a boiler co-combustion device C. Among them, biomass gasification device A uses biomass as raw material, and uses biomass raw material to obtain biomass gasification products. Biomass gasification products mainly include biomass coke and gaseous products; biomass gasification product separation and conveying device B is used to separate the biomass gasification product and transport it to the boiler co-combustion device C to co-combust with coal; the boiler co-combustion device C is used to co-combust the biomass gasification product obtained in the biomass gasification device with coal in the boiler burn. This system converts biomass with large differences in properties into gasification products with relatively uniform properties, which effectively solves the limitation of boilers on the adaptability of raw materials, and at the same time converts biomass particles into gas, liquid and solid three-state products, which are respectively put into the boiler Co-combustion significantly improves the utilization efficiency and co-combustion effect of biomass, and makes full use of the combustion characteristics of gasification products to reduce the content of nitrogen oxides in flue gas.

Each device in the system will be explained and described in detail below.

Biomass gasification device A is specifically in the form of a fixed bed, which has strong adaptability to biomass raw materials and can mix one type of biomass or multiple types of biomass, such as straw, chaff, cotton stalk, sawdust, bark, etc. Waste, trees and other woods, etc., utilize various biomass energy to the greatest extent to achieve better energy utilization and environmental protection; its operating conditions can be changed, and according to the needs of the boiler co-combustion device C, the reaction can be adjusted Temperature, residence time, biomass type and particle size and other conditions can be used to obtain three-state products with different proportions and components, so as to achieve the best co-combustion effect. In addition, the diversity of biomass raw materials used, after gasification of biomass with different characteristics, the difference in the properties of the gasification products obtained is small, which effectively solves the limitation of the boiler's adaptability to raw materials.

Specifically, the biomass gasification device A includes a biomass feeder 1 and a gasification reactor 2, and the biomass feeder 1 is connected to the gasification reactor 2, which is used to transport biomass raw materials to the gasification reactor 2 Middle; the gasification reactor 2 is used as a container for the gasification reaction of biomass raw materials, and the biomass is gasified to generate biomass coke and gaseous products. The top output of furnace 2 is ready for subsequent processing. The bottom of the biomass gasification device A is provided with an air inlet, which is used to input high-temperature flue gas. Specifically, the high-temperature flue gas pipeline 14 is connected to the air inlet of the biomass gasification device A and the boiler co-combustion device C The tail of the boiler, so that the high-temperature flue gas at the tail of the boiler can be directly used to provide the energy, O ₂ and CO ₂ required for the gasification reaction to the gasification reactor. In order to facilitate the extraction of high-temperature flue gas in the boiler, a fan 13 is installed on the high-temperature flue gas pipeline 14, wherein the temperature of the high-temperature flue gas is 100°C to 1200°C, and the composition is about 5% O ₂ , 14% CO ₂ , 15% H ₂ O, 65.8% nitrogen and 0.2% nitrogen oxides and sulfur oxides. The gasification reaction furnace 2 is also provided with a gas outlet and a discharge port, and the gas outlet is connected to the biomass gasification product separation and delivery device B through the co-combustion fuel transportation pipeline 12, and is used to discharge the gaseous products in the gasification reaction furnace. The discharge port is connected to the biomass gasification product separation and delivery device B through the co-combustion fuel transportation pipeline 12, and is used for discharging the biomass coke obtained from the gasification.

As shown in Figure 1, the boiler co-combustion device C includes a boiler 6 and a chimney 7 connected to the tail of the boiler 6, which can be used according to different biomass raw materials and different three-state products (biomass coke, bio-oil and gasification gas) According to the operating conditions of the boiler, change the injection mode and proportion of primary air, secondary air, tertiary air, exhaust air, and pulverized coal, and change the position of the gasification product nozzle at the same time , Injection method, to achieve the highest thermal efficiency and the lowest pollutant emissions. In the figure, a is the burnout zone, b is the reburning zone, and c is the main combustion zone.

The biomass gasification product separation and conveying device B separates the biomass gasification product and distributes it to the boiler in an optimal way for co-combustion with coal, which includes a gas-solid separator 3, a bio-oil liquefaction separator 4 and a coal mill 11 , the gas-solid separator 3 separates the gaseous products leaving the gasification reactor to obtain solid particles, and separates the biomass coke remaining in the gasification reactor 2, mixes the two parts of the solid product, and then mixes them with coal After being ground by the coal mill 11, it is sprayed into the furnace of the boiler 6 for co-combustion. By co-combusting coke and coal, the heterogeneous reduction characteristics of coke can be used to reduce the nitrogen oxides produced during the combustion of pulverized coal and reduce the emission of nitrogen oxides in the flue gas. The bio-oil liquefaction separator 4 further condenses and separates the separated gaseous products to obtain bio-oil and gasification gas. The bio-oil is collected by the bio-oil collector 5 and then stored in the oil tank 10 .

Among them, the gasification gas is injected into the reburning zone in the middle of the boiler furnace as a reburning fuel to form a reduction zone, which reduces the nitrogen oxides generated by coal combustion into N ₂ , further reduces the formation of nitrogen oxides, and reduces the nitrogen oxides in the combustion flue gas. substance content. Bio-oil is sprayed into the re-burning zone in the middle of the boiler furnace as a re-burning fuel to form a reduction zone to reduce the nitrogen oxides formed by coal combustion to N ₂ , thereby reducing boiler NO _X emissions; or the bio-oil can be passed into the boiler’s The primary tuyere 9 is used as the ignition oil of the boiler; or the bio-oil can be passed into the primary tuyere 9 and the secondary tuyere 8 of the boiler to be used as the stable combustion oil of the boiler, replacing diesel and heavy oil, and realizing biomass energy Efficient cascade utilization.

The embodiment of the present invention also provides a method for co-combustion of biomass gasification products and coal, which uses the system of the present invention to realize co-combustion of biomass gasification products and coal, which mainly includes the following steps:

S1. Using biomass gasification device A to obtain biomass gasification products with biomass as raw material:

S11. Open the high-temperature flue gas pipeline 14 connecting the biomass gasification device A and the boiler co-combustion device C, and deliver the energy, O ₂ and CO ₂ required for the gasification reaction to the biomass gasification device A to ensure the gasification reaction The atmosphere and temperature in the furnace are suitable for gasification;

S12. The biomass raw material is continuously transported to the biomass gasification device A through the biomass feeder 1, and gasified rapidly to obtain biomass coke and gaseous products;

S2. Use the biomass gasification product separation and delivery device B to separate the biomass gasification product and transport it to the boiler co-combustion device C:

S21. Separating the solid particles in the gaseous products, collecting the solid particles, and separating the biomass coke in the biomass gasification device A, mixing the solid particles with the biomass coke and then mixing them with coal, and then transporting them to the boiler in combustion plants;

S22. Condensing and separating the separated gaseous products to obtain bio-oil and gasification gas, and transporting the bio-oil and gasification gas to the boiler co-combustion device respectively;

S3. Using the boiler co-combustion device C to co-combust the three-state products of biomass coke, bio-oil and gasification gas obtained in the biomass gasification device and coal in the boiler.

The following are specific embodiments of the present invention, through which the present invention is further described.

When the system is in operation, the crushed and dried corn stalks with a particle size of no more than 50mm are first transported to the gasification reactor through the biomass feeder. The energy of the gasification reactor and O ₂ and CO ₂ are extracted from the tail of the boiler The temperature of the high-temperature flue gas is 1000°C, which realizes the efficient and continuous operation of the gasifier; under the atmosphere and heating of the circulating high-temperature flue gas, the corn straw particles are gasified at 500°C to produce volatile matter and coke; the volatile matter is discharged through the gas outlet at the upper end of the gasification reactor, and the coke is discharged through the discharge port at the lower end of the gasification furnace; after the volatile matter passes through the gas-solid separator, the fine coke particles entrained in the volatile matter are separated and separated The released coke particles fall into the coke conveying pipeline; the separated volatile matter enters the bio-oil separator, and the volatile matter condenses to produce bio-oil, which enters the bio-oil collector and then passes into the oil tank; the non-condensable part for vaporized gas;

The collected coke is mixed with coal through the conveying pipeline, and then sprayed into the main combustion area of the furnace after being ground by the coal mill; the gasification gas is injected into the reburning area in the middle of the furnace through a separate nozzle, and co-combusted together; bio-oil is produced from bio-oil After the collector comes out, it is divided into two parts: one part is sprayed into the reburning zone; the other part enters the oil tank, and then divided into two ways as primary air and secondary air stable combustion oil and secondary air large oil gun stable combustion oil.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be Included within the protection scope of the present invention.

Claims (10)

1. the system that a gasification of biomass product burns with coal cofiring, it is characterised in that this system includes Biomass gasification device (A), gasification of biomass product separate transfer (B) and boiler cofiring burn Device (C), wherein:

Described biomass gasification device (A) is with biomass as raw material, and utilizes this biomass material to obtain Gasification of biomass product, described gasification of biomass product includes biomass char and gaseous products；

Described gasification of biomass product separate transfer (B) is for separating gasification of biomass product also It is transported in boiler burner (C) altogether and coal cofiring；

Described boiler burner (C) altogether is for the gasification of biomass that will obtain in biomass gasification device Product and coal cofiring in the boiler.

The system that gasification of biomass product the most according to claim 1 burns with coal cofiring, it is characterised in that Described biomass gasification device (A) includes biomass feeder (1) and gasification reacting furnace (2), institute Stating biomass feeder (1) to be connected with gasification reacting furnace (2), it is for carrying biomass material To gasification reacting furnace (2)；Described gasification reacting furnace (2) is as biomass material gasification reaction Container, is connected with the boiler tail in boiler altogether burner (C) bottom it, directly utilizes pot with this The high-temperature flue gas of stove afterbody provides the energy needed for gasification reaction, O for gasification reacting furnace₂And CO₂。

The system that gasification of biomass product the most according to claim 2 burns with coal cofiring, it is characterised in that Boiler in described gasification reacting furnace (2) and boiler burner (C) altogether is by high-temperature flue gas pipeline (14) it is connected, this high-temperature flue gas pipeline (14) is provided with blower fan (13), in order to extraction pot High-temperature flue gas in stove.

The system that gasification of biomass product the most according to claim 3 burns with coal cofiring, it is characterised in that Described boiler burner (C) altogether includes boiler (6) and the chimney being connected with boiler (6) afterbody (7)。

The system that gasification of biomass product the most according to claim 1 burns with coal cofiring, it is characterised in that Described gasification of biomass product separate transfer (B) includes gas-solid separator (3), biological fluid Separator (4) and coal pulverizer (11), described gas-solid separator (3) will leave gasification reacting furnace Gaseous products carry out separate obtain solid particle, this solid particle mix with biomass char and coal after also Cofiring in the burner hearth of boiler (6) is sprayed into, to utilize the different of biomass char after coal pulverizer (11) grinds Phase reduction characteristic, the nitrogen oxides produced in reduction process of coal combustion, and then reduce nitrogen oxygen in flue gas The discharge of compound；Described bio oil liquefaction separator (4) will condense through the gaseous products separated To obtain the gentle activating QI of bio oil, described bio oil is collected in bio oil catcher (5).

The system that gasification of biomass product the most according to claim 5 burns with coal cofiring, it is characterised in that Described gasification gas sprays into the reburning zone in the middle part of boiler furnace as reburning fuel, to form reducing zone, and will The coal-fired nitrogen oxides generated is reduced into N₂, and then the generation of reduction nitrogen oxides, reduce combustion product gases The content of middle nitrogen oxides.

The system that gasification of biomass product the most according to claim 5 burns with coal cofiring, it is characterised in that Described bio oil sprays into the reburning zone in the middle part of boiler furnace as reburning fuel, to form reducing zone, and will The nitrogen oxides that coal combustion is formed is reduced into N₂, and then reduce boiler NO_XDischarge capacity；Or by bio oil It is passed through in the primary air nozzle of boiler, using the ignition oil as boiler；Or bio oil is passed through boiler In primary air nozzle and overfiren air port, using the stable combustion oil as boiler, and then realize biomass energy Efficiently cascade utilization.

8. the system burnt with coal cofiring according to the gasification of biomass product of claim 2 and 3, its feature Being, the temperature of described high-temperature flue gas is 100 DEG C～1200 DEG C, and constituent is 5%O₂, 14%CO₂、 15%H₂O, 65.8% nitrogen and the nitrogen oxides of 0.2% and oxysulfide.

9. the method that a gasification of biomass product burns with coal cofiring, it is characterised in that include walking as follows Rapid:

S1, biomass gasification device (A) is utilized to obtain gasification of biomass product with biomass for raw material, Gasification of biomass product includes biomass char and gaseous products；

S2, utilize gasification of biomass product separate transfer (B) by gasification of biomass product separate also It is transported in boiler burner (C) altogether；

S3, utilize the gasification of biomass that boiler altogether burner (C) will obtain in biomass gasification device Product and coal cofiring in the boiler.

The method that gasification of biomass product the most according to claim 9 burns with coal cofiring, it is characterised in that Step S1 includes following sub-step:

The high temperature cigarette of S11, unlatching connection biomass gasification device (A) and boiler burner (C) altogether Feed channel (14), carries the energy needed for gasification reaction, O in biomass gasification device (A)₂With CO₂；

S12, biomass material are transported to biomass gasification device through biomass feeder (1) continuous print (A) in, and Quick-gasifying is to obtain biomass char and gaseous products；

Step S2 includes following sub-step:

S21, solid particle in gaseous products is separated, collect solid particle, and by biogas Biomass char in gasifying device (A) is separated, after solid particle and biomass char are mixed again with coal Mixing, is then sent to cofiring in boiler burner (C) altogether；

S22, the gaseous products of separation is carried out condensation separation obtain the gentle activating QI of bio oil, by bio oil Gentle activating QI is respectively delivered in boiler burner altogether.