CN204400906U - Pulverized coal pyrolysis pollutant disposal system and boiler combustion system - Google Patents

Abstract

The utility model relates to a pulverized coal pyrolysis pollutant treatment system and a boiler combustion system, wherein the pulverized coal pyrolysis pollutant treatment system includes a flue gas extraction subsystem for extracting flue gas and responsible for transporting the flue gas, and a flue gas extraction subsystem for passing flue gas Gas pyrolyzes the received coal powder to produce pyrolysis gas and semi-coke pyrolysis subsystem and semi-coke activation subsystem for activating and forming semi-coke. The utility model uses the flue gas generated in the boiler It is transported to the pulverized coal pyrolysis furnace, and the pulverized coal is pyrolyzed to produce pyrolysis gas and semi-coke. The pyrolysis gas has a reduction function, and the pyrolysis gas is passed into the boiler to reduce the pollution caused by fuel combustion in the boiler. After being activated and _shaped , the semi-coke produced in the pyrolysis process can be used as an adsorbent to absorb SO _x produced by fuel combustion in the boiler, so as to achieve the purpose of reducing pollutant emissions and protecting the environment.

Description

Pulverized coal pyrolysis pollutant treatment system and boiler combustion system

technical field

The utility model relates to the technical field of pulverized coal combustion, in particular to a pulverized coal pyrolysis pollutant treatment system and a boiler combustion system.

Background technique

The rapid development of the thermal power industry in recent years has greatly promoted the development of the national economy, but it has also caused serious environmental pollution. When pulverized coal is burned, it will produce dust, NO _x , SO _x , CO and other pollutants, and these products will cause environmental pollution to the atmosphere. Among them, SO _x mainly exists in the form of SO ₂ after being discharged into the atmosphere. When the concentration and existence of SO ₂ in the air exceed a certain value, it will cause damage to plants; NO in the NO _x produced by combustion accounts for about 90% to 95%. The NO produced at any temperature will be converted into NO ₂ , while NO _x is irritating to the human respiratory system, even causing chronic poisoning, and causing great damage to plants in nature. In addition, both gases will react with other pollutants in the atmosphere to form photochemical smog, which is more harmful, so it is very important for the control of SO _x and NO _x .

With the increasingly stringent national environmental protection policies, higher environmental protection requirements have been put forward for the power industry, especially for thermal power units. Among these pollutants, _NOx and _SOx are more difficult to deal with. At present, the technical means to reduce SO _x mainly include pre-combustion (treatment of fuel), during combustion (in-furnace desulfurization, mainly fluidized bed combustion technology and furnace calcium injection technology) and post-combustion (flue gas desulfurization technology). At present, the most widely used and most effective technology is flue gas desulfurization technology, mainly including limestone-gypsum wet method, spray drying method, calcium spraying in furnace plus tail humidification activation method, flue gas circulating fluidized bed desulfurization method, etc., but these The method generally has problems such as high initial investment and operating costs, many constraints in design and operation, and easy to cause secondary pollution, and most desulfurization by-products cannot be recovered or have low utilization value.

At present, the technical means for reducing NO _x in coal-fired power plants are mainly realized through low-nitrogen combustion technology and selective catalytic reduction technology (hereinafter referred to as SCR technology). However, with the change of operating coal type and the burning loss of combustion equipment, the emission of _NOx will exceed the design value. In order to achieve lower _NOx emission during operation, the amount of oxygen in boiler operation should be reduced, but this will lead to The occurrence of high-temperature corrosion of the water wall will also lead to an increase in the unburned heat loss of the boiler. After long-term operation, the low-nitrogen combustion technology cannot meet the design requirements. Although the SCR technology can control the NO _x in the flue gas well by controlling the amount of ammonia injection, it also has disadvantages such as large initial investment, high operating cost, expensive catalyst, and the danger of ammonia leakage.

In the prior art, there is a decoupled circulating fluidized bed combustion system and its desulfurization and denitrification method. For the fluidized bed combustion technology, the coal combustion in the circulating bed is divided into two steps: isolated air dry distillation and semi-coke combustion, in order to solve the problem of desulfurization. Contradictions with denitrification. The sulfur-containing gas released during the dry distillation of raw coal is captured by the desulfurizer, and the semi _- coke produced by the dry distillation enters the desulfurization zone at the lower part of the combustion zone.

The main technology used to remove SO _x and NO _x in this method is fluidized bed combustion technology, but this technology has relatively large limitations. While removing SO _x , this technology needs to add Desulfurization agent is used to achieve this, and this method is relatively limited to the combustion method of fluidized bed combustion. The addition of desulfurization agent will cause serious wear and tear on the water wall of the fluidized bed boiler furnace, and will pose a threat to the normal operation of the boiler. This method is also difficult to control NO _x to a low level, and it needs to cooperate with the flue gas treatment technology of the tail flue to meet the requirements of environmental protection.

In the prior art, there is also a method of co-combusting gas fuel in pulverized coal boilers to reduce nitrogen oxides. The gas fuel is introduced into the pulverized coal furnace in two stages, and the primary gas fuel is introduced at the bottom of the main burner in the main combustion zone as a combustion-supporting fuel. And adopt the "horizontal thick-lean air" combustion technology in the main combustion area and burn under the low air excess coefficient or the overall reducing atmosphere; introduce secondary gas fuel at the top of the main combustion area to form a reburning area with a reducing atmosphere; at the top of the reburning area Introduce burnout air to complete burnout.

Although this method uses gas fuel reburning combined with air staged combustion and horizontal dense-lean air combustion technology to achieve low _NOx combustion in the furnace, this method has relatively large limitations on gas and is suitable for boilers with stable gas sources. The requirements are higher, and the SO _x in the flue gas needs to be dealt with separately.

Utility model content

The purpose of the utility model is to provide a pulverized coal pyrolysis pollutant treatment system and a boiler combustion system to reduce the discharge of pollutants during the pulverized coal combustion process as much as possible.

In order to achieve the above purpose, the utility model provides a pulverized coal pyrolysis pollutant treatment system, including: a flue gas extraction subsystem, which is used to extract the flue gas and is responsible for transporting the flue gas;

The pyrolysis subsystem is used to pyrolyze the received coal powder through the flue gas to produce pyrolysis gas and semi-coke;

semi-coke activation subsystem, used for activating and shaping the semi-coke;

The pollutant treatment subsystem is used to reduce the _NOx produced by the combustion of fuel in the boiler through the pyrolysis gas, and desulfurize the pollutants produced by the combustion of fuel in the boiler through the formed semi-coke .

Further, the flue gas extraction subsystem includes a flue gas extraction pipe, the first end of the flue gas extraction pipe is connected to the boiler, and the second end of the flue gas extraction pipe is connected to the pyrolysis subsystem.

Further, the first end is located after the reheater installed in the boiler and before the economizer.

Further, the temperature of the flue gas is 600°C-800°C.

Further, the smoke extraction subsystem further includes a smoke fan, which provides power for extracting the smoke.

Further, the pyrolysis subsystem includes a pulverized coal pyrolysis furnace and a pyrolysis product outlet pipe, and the flue gas and the pulverized coal respectively pass through the flue gas injection inlet and the coal pulverized coal pyrolysis furnace. The powder injection inlet enters the pulverized coal pyrolysis furnace, and the pyrolysis product outlet pipe is arranged at the outlet of the pulverized coal pyrolysis furnace.

Further, the pyrolysis subsystem also includes at least one pulverized coal injector connected to the pulverized coal injection inlet for injecting the pulverized coal into the pulverized coal pyrolysis inside the furnace.

Further, the pyrolysis subsystem also includes a cyclone separator, which is arranged at the outlet pipe of the pyrolysis product, and is used for separating the pyrolysis gas and the semi-coke.

Further, the pyrolysis subsystem also includes a reburning gas pipeline, and the reburning gas pipeline can transport the pyrolysis gas into the boiler.

Further, the semi-coke activation subsystem includes a semi-coke activation device and a semi-coke shaping device, the semi-coke activation device is used to receive the semi-coke and activate the semi-coke, and the semi-coke shaping device Used to shape the semi-coke after activation.

Further, the semi-coke activation device is provided with at least one water inlet and at least one steam outlet, the at least one water inlet is arranged at the middle lower position of the semi-coke activation device, and the at least one steam outlet is arranged On the upper side of the semi-coke activation device.

To achieve the above purpose, the utility model also provides a boiler combustion system, including a boiler and the above-mentioned pulverized coal pyrolysis pollutant treatment system, wherein the boiler is provided with a reburning gas burner and a main combustion device, and the reburning A gas burner is connected to the reburning gas pipeline.

Further, the reburning gas burner is arranged above the main combustion device.

Further, the reburning gas pipeline is led out from the pyrolysis subsystem and divided into two paths, one path enters the reburning gas burner on one side of the boiler, and the other path enters the reburning gas burner on the other side of the boiler .

Further, the boiler combustion system also includes a semi-coke burner, which is used to burn the desulfurized and dried semi-coke after deactivation.

Further, the semi-coke burner is arranged below the reburning gas burner and above the main combustion device.

Further, the boiler combustion system also includes an overfired air burner, which is arranged above the reburning gas burner to ensure that the combustibles in the boiler are burnt out.

Further, the main combustion device includes an upper burner, a middle burner and a lower burner, and performs staged combustion on the fuel entering the boiler.

Based on the above technical solution, the utility model transports the flue gas generated in the boiler to the pulverized coal pyrolysis furnace to pyrolyze the pulverized coal to produce pyrolysis gas and semi-coke. The pyrolysis gas has a reduction function, and the thermal The decomposed gas is passed into the boiler, which can reduce the NO _x in the pollutants produced by the combustion of the fuel in the boiler. The semi-coke produced in the pyrolysis process can be used as an adsorbent to absorb the SO _x produced by the combustion of the fuel in the boiler after being activated and shaped. So as to achieve the purpose of reducing pollutant emissions and protecting the environment.

Description of drawings

The drawings described here are used to provide a further understanding of the utility model and constitute a part of the application. The schematic embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute improper limitations to the utility model. In the attached picture:

Figure 1 is a schematic diagram of the composition and structure of an embodiment of the utility model coal powder pyrolysis pollutant treatment system.

Fig. 2 is a structural schematic diagram of an embodiment of the boiler combustion system of the present invention.

In the figure: 1- pulverized coal injector, 2- pulverized coal pyrolysis furnace, 3- pyrolysis product outlet pipe, 4- cyclone separator, 5- steam outlet, 6- water inlet, 7- semi-coke activation device, 8-semi-coke forming device, 9-reburning gas burner, 10-reburning gas pipeline, 11-boiler, 12-flue gas fan, 13-overfired air burner, 14-semi-coke burner, 15-upper burner , 16- middle burner, 17- lower burner, 18- economizer, 19- flue gas extraction pipe, 20- reheater, 21- air preheater, 22- dust collector, 23- desulfurization device, 24- chimney.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

In describing the present invention, it should be understood that the terms "center", "transverse", "longitudinal", "front", "rear", "left", "right", "upper", "lower", The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention. The novel and simplified descriptions do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the protection scope of the present utility model.

At first the terms that will be involved in the utility model are explained, as follows:

Coal pyrolysis: refers to the complex process in which coal is heated in the absence of air, and a series of physical and chemical changes occur at different temperatures.

Semi-coke: It is a solid product with a short blue flame when burning, which is obtained after dry distillation of coal powder at a certain temperature, and has a rich pore structure inside.

Activation: refers to the method of changing the physical structure of the surface of the semi-coke by enlarging the micropores inside the semi-coke and opening the closed pores after the semi-coke is treated by physical or chemical methods.

The utility model content of the utility model is described below in conjunction with the accompanying drawings and multiple embodiments.

First of all, in order to solve the problem of more pollutants produced by coal combustion in the prior art as much as possible, the utility model provides a pulverized coal pyrolysis pollutant treatment system, as shown in Fig. Schematic diagram of the composition and structure of the solution pollutant treatment system, which includes:

a smoke extraction subsystem, used for extracting smoke and responsible for delivering said smoke;

The pyrolysis subsystem is used to pyrolyze the received coal powder through the flue gas to produce pyrolysis gas and semi-coke;

semi-coke activation subsystem, used for activating and shaping the semi-coke;

The pollutant treatment subsystem is used to reduce the _NOx produced by the fuel combustion in the boiler 11 through the pyrolysis gas, and to reduce the pollutants produced by the fuel combustion in the boiler 11 through the formed semi-coke Desulfurization treatment.

The pulverized coal pyrolysis pollutant treatment system proposed by the utility model combines pulverized coal pyrolysis, gas reburning reduction _NOx technology and desulfurization technology to form an integrated process. The pyrolysis gas produced by pulverized coal pyrolysis includes CO ₂ , CO, H ₂ , HCN, C _x H _y , H ₂ O, etc., among which H ₂ , HCN, and C _x H _y have a strong reduction effect on NO _x , so the utility model utilizes gas reburning reduction NO _x technology , the pulverized coal pyrolysis gas is sent to the reburning zone in the furnace, and the NO _x produced by the pulverized coal combustion in the main combustion zone is reduced to N ₂ , that is, the hot flue gas generated by the system itself is used to generate pyrolysis gas from the pulverized coal, thereby reducing NO _x is reduced, and after selecting an appropriate reburning ratio, _NOx can be reduced to a lower level through furnace reburning technology to achieve the purpose of denitrification. In addition, the remaining semi-coke from pyrolysis is used as a desulfurization adsorbent, and the tail flue can meet environmental protection requirements without installing an SCR device. The treated by-products after absorbing SO _x can also be sent to the furnace for combustion, improving the utilization of substances Rate.

The utility model uses semi-coke, which is one of the products of pulverized coal pyrolysis, as an adsorbent, and supplies it to the desulfurization device 23 installed in the tail flue of the boiler. There are many options for the position of the desulfurization device 23, for example, it can be installed in the tail flue After the deduster 22, the pollutants produced by the combustion of fuel in the boiler are subjected to adsorption and desulfurization treatment, and the treated flue gas is discharged through the chimney 24, which can minimize the emission of sulfur-containing pollutants and reduce the cost of initial equipment investment. There is no need to design a system for desulfurization. The pulverized coal pyrolysis pollutant treatment system of the utility model can achieve the purpose of desulfurization by using another product produced in the _NOx reduction process, which is simple, practical and economical.

The utility model uses the flue gas (the temperature of the flue gas can be 600°C to 800°C) as a heat source to pyrolyze the coal powder, ensuring the temperature and at the same time ensuring the atmosphere environment where the coal powder pyrolysis is located, so that the pyrolysis gas The quality is guaranteed, the problem of reburning gas source is well solved, the interference to the normal operation of the boiler is reduced, the energy is fully utilized, and the purpose of denitrification is achieved. It is simple, reliable and practical.

In one embodiment, the smoke extraction subsystem includes a smoke extraction pipe 19, the first end of the smoke extraction pipe 19 is connected to the boiler 11, and the second end of the smoke extraction pipe 19 is connected to the Pyrolysis subsystem connections.

Wherein, there are many sources of the flue gas, and there are also many choices for the temperature of the flue gas. Preferably, the first end is located after the reheater 20 installed in the boiler 11 and before the economizer 18 .

Preferably, the utility model uses hot flue gas with a temperature of 600°C to 800°C after the reheater and before the economizer as a heat source to pyrolyze the pulverized coal. This method of pyrolysis can effectively control the overall atmosphere in the pulverized coal pyrolysis furnace, because when the pulverized coal is pyrolyzed, oxygen has a great influence on the composition of the pyrolysis gas generated during the pyrolysis process, and the lower the oxygen content , the proportion of reducing atmosphere in the pyrolysis gas will be higher, so using hot flue gas as a heat source can effectively avoid the mixing of air. The oxygen content of the flue gas here is low, which can effectively ensure the quality of the gas components after coal powder pyrolysis.

The flue gas temperature is preferably 600°C to 800°C, mainly considering: first, this temperature range can meet the temperature required for coal powder pyrolysis; second, the flue gas temperature at the outlet of the boiler reheater is generally at 800°C Third, when the temperature is too high, the material requirements for the relevant pipelines are too high, and there are potential safety hazards during operation. Therefore, after comprehensive consideration of the above factors, the required flue gas extraction position is set after the reheater and before the economizer, and the flue gas temperature is selected to be 600°C to 800°C. Of course, if the temperature required for pyrolysis becomes higher or lower, the material of the pipe can also be improved to meet higher requirements, and there are many other options for the extraction position and temperature of the flue gas.

In another embodiment, the smoke extraction subsystem further includes a smoke fan 12, and the smoke fan 12 provides power for extracting the smoke.

In one embodiment, the pyrolysis subsystem may include a pulverized coal pyrolysis furnace 2 and a pyrolysis product outlet pipe 3, and the flue gas and the pulverized coal pass through the pulverized coal pyrolysis furnace 2 respectively. The flue gas injection inlet and the pulverized coal injection inlet enter the pulverized coal pyrolysis furnace 2, and the pyrolysis product outlet pipe 3 is arranged at the outlet of the pulverized coal pyrolysis furnace 2.

Preferably, the pyrolysis subsystem also includes at least one pulverized coal injector 1 connected to the pulverized coal injection inlet for injecting the pulverized coal into the pulverized coal Inside the pyrolysis furnace 2.

More preferably, the pyrolysis subsystem further includes a cyclone separator 4, the cyclone separator 4 is arranged at the pyrolysis product outlet pipe 3, and is used to separate the pyrolysis gas and the semi-coke .

There are many ways to separate pyrolysis gas and semi-coke, as long as the function can be realized. For example, a cyclone separator or other devices with separation function can be used to separate the two, the pyrolysis gas is passed into the boiler, and the semi-coke is transported to the semi-coke activation device for activation.

In addition, the pyrolysis subsystem further includes a reburning gas pipeline 10 capable of transporting the pyrolysis gas into the boiler 11 .

In one embodiment, the semi-coke activation subsystem includes a semi-coke activation device 7 and a semi-coke shaping device 8, the semi-coke activation device 7 is used to receive the semi-coke and activate the semi-coke, The semi-coke shaping device 8 is used to shape the activated semi-coke.

In the above embodiments, the purpose of activating the semi-coke is to expand the micropores inside the semi-coke and open the closed pores, thereby changing the physical structure of the surface of the semi-coke to make it have an adsorption function, so that the semi-coke can be used as an adsorbent. Desulfurize the pollutants produced by the combustion of fuel in the boiler. There are many ways to activate semi-coke, including physical and chemical.

An important product after pulverized coal pyrolysis is semi-coke. The interior of semi-coke has a very developed microporous structure. After activation and modification, semi-coke will have a strong adsorption effect. Therefore, the utility model adopts a simple An effective modification method is to modify the semi-coke product, that is, to use the activation method of mixing the high-temperature semi-coke product with water through the semi-coke activation device to increase the surface area inside the semi-coke to be used as an adsorbent for SO _x Therefore, the desulfurization process in the utility model does not need to use catalytic reduction technology, and the SCR denitrification device often used in the prior art arranged in the tail flue can be canceled or reduced to save infrastructure and operating costs.

In addition, at least one water inlet 6 and at least one steam outlet 5 can be set on the semi-coke activation device 7, and the at least one water inlet 6 is arranged at the middle lower position of the semi-coke activation device 7, and the at least A steam outlet 5 is arranged on the upper side of the semi-coke activation device 7 . The utility model uses water to directly activate the high-temperature solid semi-coke. After activation, the molding technology is directly used for shaping treatment. The water inlet is arranged at the middle and lower position, which is convenient for direct contact between the cooling water and the high-temperature solid semi-coke, and the steam outlet is arranged at the top. The side is convenient for the cooling water to vaporize directly when it encounters high-temperature solid semi-coke, and is discharged from the steam outlet on the upper side.

Using water to activate semi-coke is simple and reliable. It can quickly and completely activate the semi-coke, and then use the semi-coke forming device to process the activated semi-coke to form activated semi-coke with a certain shape. Coke can be used as an adsorbent to adsorb and desulfurize the pollutants produced by fuel combustion in the boiler.

The above settings can save raw materials and protect the safe operation of the equipment. When the load of the boiler is not too large, the injection amount of pulverized coal can be increased appropriately, and the extraction amount of flue gas can be increased appropriately, so as to speed up the pulverized coal production. During the pyrolysis process, more pyrolysis gas and semi-coke are produced, and the input of water for activation of semi-coke needs to be increased accordingly to desulfurize and denitrify pollutants to a greater extent; when the load of the boiler has reached To a certain extent, it is possible to control the injection amount of pulverized coal and the extraction amount of flue gas, so as to reduce the pyrolysis speed of pulverized coal, and at the same time reduce the input amount of water for activation of semi-coke, which not only saves energy, but also prevents Boiler overload operation, resulting in equipment damage.

Based on the above-mentioned pulverized coal pyrolysis pollutant treatment system, the utility model also proposes a boiler combustion system, as shown in FIG. 2 , which is a schematic structural diagram of an embodiment of the utility model boiler combustion system. The boiler combustion system includes a boiler 11 and the above-mentioned pulverized coal pyrolysis pollutant treatment system, wherein the boiler 11 is provided with a reburning gas burner 9 and a main combustion device, and the pulverized coal pyrolysis pollutant treatment system includes a reburning gas Pipeline 10 , the reburning gas burner 9 is connected with the reburning gas pipeline 10 .

Preferably, the reburning gas burner 9 is arranged above the main combustion device.

The position of the reburning gas burner can be selected in many ways, but the gas generated by fuel combustion all rises upwards, and the reburning gas burner can be preferably set above the main combustion device, so that the pollutants generated by fuel combustion can pass through the reburning The section where the gas burner is located, the reburning gas burner is connected to the reburning gas pipeline, and the pyrolysis gas with reducing properties produced by pyrolysis in the reburning gas pipeline can reduce NO _x in pollutants to N ₂ .

More preferably, the reburning gas pipeline 10 is led out from the pyrolysis subsystem and divided into two paths, one path enters the reburning gas burner 9 on one side of the boiler 11, and the other path enters the other side of the boiler 11 The reburning gas burner9. Dividing the reburning gas pipeline into two paths can enhance the mixing degree of the pyrolysis gas in the boiler and the flue gas generated in the main combustion zone, making the reduction more complete.

In one embodiment, the boiler combustion system further includes a semi-coke burner 14, which is used to burn the desulfurized and dried semi-coke after deactivation. After the desulfurization and drying treatment of the semi-coke adsorbent after adsorption, it can be used as fuel again and sent to the semi-coke burner for combustion to improve the utilization rate of the substance.

Among them, the process of drying semi-coke can use the flue gas taken from after the air preheater. The air preheater 21 is set between the economizer 18 and the dust collector 22. required without compromising boiler efficiency. The function of the air preheater is to exchange heat between the air and flue gas required by the boiler to preheat the air. If the flue gas from other places is extracted to dry the coke, for example, the flue gas before the air preheater is selected, although the temperature is also It can meet the drying temperature requirements, but it will reduce the amount of flue gas passing through the air preheater, reduce the temperature of the air after heat exchange, and reduce the efficiency of the boiler. Of course, if the flue gas from other places can meet the drying requirements without affecting the efficiency of the boiler, it can also be used to dry the semi-coke.

In another embodiment, the semi-coke burner 14 is arranged below the reburning gas burner 9 and above the main combustion device. The semi-coke burner is arranged between the reburning gas burner and the upper burner, which can ensure that the semi-coke can be completely burned without affecting the heat loss of the unburned embers of the boiler.

Preferably, the boiler combustion system further includes an overfired air burner 13, which is arranged above the reburning gas burner 9 to ensure that the combustibles in the boiler 11 are burned out . The purpose of burnout treatment is to fully burn the fuel and avoid half-combustion or incomplete combustion of the fuel, resulting in waste of resources.

More preferably, the main combustion device includes an upper burner 15 , a middle burner 16 and a lower burner 17 , and performs staged combustion on the fuel entering the boiler 11 .

Among them, the semi-coke burner 14, the upper burner 15, the middle burner 16 and the lower burner 17 constitute the main combustion area of the boiler, and the main combustion device is divided into three burners to realize the reburning reduction gas technology and low nitrogen combustion technology The combination of the air classification technology in the boiler can reduce the NO _x at the outlet of the boiler furnace to the level required by the environmental protection and meet the environmental protection requirements.

Among them, the air classification technology refers to the classification treatment of the air delivered to the boiler through multiple burners, so as to control the production of nitrogen-containing pollutants during the combustion process and reduce the _NOx produced by fuel combustion in the boiler. Here Without using the air classification technology, the utility model can still achieve the purpose of reducing _NOx by using the pyrolysis gas, but the pulverized coal pyrolysis pollutant treatment system of the utility model combines the technology of reducing _NOx by the pyrolysis gas of the utility model with the boiler Combining with the air classification technology adopted in the main combustion process in the interior, the emission of pollutants can be reduced to the greatest extent, so that the pollutants in the flue gas discharged into the air can meet the environmental protection requirements.

The working process of an embodiment of the pulverized coal pyrolysis pollutant treatment system and boiler combustion system of the present invention will be described below:

Firstly, the flue gas with a temperature of 600°C to 800°C before the economizer 18 in the boiler 11 is extracted by the flue gas fan 12, and sent to the pulverized coal pyrolysis furnace 2 through the flue gas extraction pipe 19, and at the same time, the Pulverized coal pulverized coal is injected into the pulverized coal pyrolysis furnace 2 through at least one pulverized coal injector 1 arranged above the pulverized coal pyrolysis furnace 2, and then the pulverized coal is pyrolyzed.

Second, the semi-coke and pyrolysis gas produced by pyrolysis of pulverized coal are sent into the cyclone separator 4 through the pyrolysis product outlet pipe 3, and after the semi-coke and pyrolysis gas are separated by the cyclone separator, the resulting pyrolysis gas ( Including CO ₂ , CO, H ₂ , HCN, C _x H _y , H ₂ O, etc.) are sent to the reburning gas burner 9 through the reburning gas pipeline 10, and the reburning gas burner 9 sprays it into the furnace for combustion.

Third, since the reburning gas burner 9 is located in the area below the overfired air burner 13 and above the main combustion zone, after the pyrolysis gas is injected into the furnace in this area, the H ₂ , HCN, C in the pyrolysis gas Reducing gases such as _x H _y can reduce the NO _x produced by the fuel in the main combustion zone to generate N ₂ . At the same time, it can also be used in conjunction with the air classification technology of the low-nitrogen combustion technology in the main combustion zone to reduce the NO _x produced by the combustion of pulverized coal in the furnace to the emission level required by environmental protection.

Fourth, the solid product of the pulverized coal pyrolysis mixture (semi-coke and pyrolysis gas) separated by the cyclone separator 4—semi-coke whose temperature is maintained at a relatively high level enters the semi-coke activation device 7 for activation.

The specific activation principle is: the utility model uses water to activate high-temperature semi-coke. On the semi-coke activation device 7, water is first introduced through the water inlet 6 arranged in the lower half. Steam outlet 5 discharges. The semi-coke activated by water vapor is discharged from the outlet of the semi-coke activation device 7 into the semi-coke forming device 8, and after being processed by the semi-coke forming device 8, the semi-coke becomes active semi-coke with a certain shape.

Fifth, the formed activated semi-coke can be used as an adsorbent for the desulfurization device 23 located in the tail flue of the boiler. The semi-coke adsorbent has a certain adsorption life. After the activated semi-coke is deactivated, it can be desulfurized by water spraying, and then dried with the flue gas after the air preheater 21. After drying, the semi-coke is broken Afterwards, it can be used as fuel and sent into the furnace for combustion by the semi-coke burner 14.

In addition, during the operation, the quantity of pulverized coal injectors 1 and the flow rate of the flue gas fan 12 can be adjusted according to the load of the boiler, that is, the injection amount of pulverized coal and the extraction amount of the flue gas fan can be adjusted, thereby The production of pyrolysis gas and semi-coke is controlled; the number of steam outlets 5 and water inlets 6 put into operation at the same time is also changed accordingly, that is, the amount of water input during the activation of semi-coke needs to be adjusted accordingly. Specifically, when the load of the boiler is low, the boiler requires less fuel, and the pollutants produced are also reduced. At this time, the amount of coal powder injected into the pyrolysis furnace can be reduced, and the amount of flue gas extraction can be appropriately reduced; Conversely, when the boiler load is high, the fuel required by the boiler increases, and the pollutants produced also increase. At this time, the amount of pulverized coal injected into the pyrolysis furnace can be increased, the amount of flue gas extracted can be appropriately increased, and the amount of coal injected can be adjusted. At the same time as the amount of powder is adjusted, the input amount of water for semi-coke activation is also adjusted.

The utility model utilizes the technical principle of flue gas pyrolysis coal powder, and well solves the problems of desulfurization and denitrification. The oxygen content in the flue gas is low, which can effectively ensure the quality of the gas components after the pyrolysis of pulverized coal. The utility model uses the pyrolysis gas as the recombustion gas, which can reduce the _NOx produced in the pulverized coal combustion process to the level required by environmental protection, and can reduce the initial investment and operation cost of the flue gas denitrification treatment SCR equipment, and the utility model combines the pyrolysis The product semi-coke is activated and used directly as a desulfurization adsorbent, and the used semi-coke can also be desulfurized and used as fuel for combustion. The utility model minimizes environmental pollution when processing _SOx and _NOx produced in the pulverized coal combustion process, and greatly reduces the initial investment and operation cost of desulfurization and denitrification.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit it; although the utility model has been described in detail with reference to the preferred embodiment, those of ordinary skill in the art should understand that: still The specific implementation of the utility model can be modified or some technical features can be equivalently replaced; without departing from the spirit of the technical solution of the utility model, all of them should be included in the scope of the technical solution claimed by the utility model.

Claims (18)

1. A pulverized coal pyrolysis pollutant treatment system is characterized in that, comprising: a smoke extraction subsystem, used for extracting smoke and responsible for delivering said smoke; The pyrolysis subsystem is used to pyrolyze the received coal powder through the flue gas to produce pyrolysis gas and semi-coke; semi-coke activation subsystem, used for activating and shaping the semi-coke; The pollutant treatment subsystem is used to reduce the _NOx produced by the combustion of fuel in the boiler (11) through the pyrolysis gas, and to reduce the NOx produced by the combustion of fuel in the boiler (11) through the formed semi-coke Pollutants are desulfurized. 2. The pulverized coal pyrolysis pollutant treatment system according to claim 1, characterized in that, said flue gas extraction subsystem comprises a flue gas extraction pipeline (19), the first of said flue gas extraction pipeline (19) One end is connected to the boiler (11), and the second end of the flue gas extraction pipe (19) is connected to the pyrolysis subsystem. 3. The pulverized coal pyrolysis pollutant treatment system according to claim 2, characterized in that, the first end is located after the reheater (20) installed in the boiler (11) and the economizer ( 18) before. 4. The pulverized coal pyrolysis pollutant treatment system according to claim 3, characterized in that the temperature of the flue gas is 600°C-800°C. 5. The pulverized coal pyrolysis pollutant treatment system according to claim 2, characterized in that, said flue gas extraction subsystem also includes a flue gas blower (12), and said flue gas blower (12) is for extracting said flue gas Smoke provides power. 6. The pulverized coal pyrolysis pollutant treatment system according to claim 1, characterized in that, the pyrolysis subsystem comprises a pulverized coal pyrolysis furnace (2) and a pyrolysis product outlet pipe (3), and the smoke The gas and the pulverized coal enter the pulverized coal pyrolysis furnace (2) through the flue gas injection inlet and the pulverized coal injection inlet respectively arranged on the pulverized coal pyrolysis furnace (2), and the pyrolysis product outlet pipe (3) It is arranged at the outlet of the pulverized coal pyrolysis furnace (2). 7. The pulverized coal pyrolysis pollutant treatment system according to claim 6, characterized in that, the pyrolysis subsystem also includes at least one pulverized coal injector (1), and the pulverized coal injector (1 ) is connected with the pulverized coal injection inlet for injecting the pulverized coal into the pulverized coal pyrolysis furnace (2). 8. The pulverized coal pyrolysis pollutant treatment system according to claim 6, characterized in that, the pyrolysis subsystem also includes a cyclone separator (4), and the cyclone separator (4) is arranged on the thermal The pyrolysis product outlet pipe (3) is used to separate the pyrolysis gas and the semi-coke. 9. The pulverized coal pyrolysis pollutant treatment system according to claim 6, characterized in that, the pyrolysis subsystem also includes a reburning gas pipeline (10), and the reburning gas pipeline (10) can dissipate the heat The decomposed gas is delivered to the boiler (11). 10. The pulverized coal pyrolysis pollutant treatment system according to claim 1, characterized in that, the semi-coke activation subsystem comprises a semi-coke activation device (7) and a semi-coke forming device (8), and the semi-coke The activation device (7) is used to receive the semi-coke and activate the semi-coke, and the semi-coke shaping device (8) is used to shape the activated semi-coke. 11. The pulverized coal pyrolysis pollutant treatment system according to claim 10, characterized in that, the semi-coke activation device (7) is provided with at least one water inlet (6) and at least one steam outlet (5), The at least one water inlet (6) is arranged at the middle lower position of the semi-coke activation device (7), and the at least one steam outlet (5) is arranged on the upper side of the semi-coke activation device (7) . 12. A boiler combustion system, characterized in that it comprises a boiler (11) and the pulverized coal pyrolysis pollutant treatment system as claimed in any one of claims 1-11, wherein the boiler (11) is provided with a reburning A gas burner (9) and a main combustion device, the pulverized coal pyrolysis pollutant treatment system includes a reburning gas pipeline (10), and the reburning gas burner (9) is connected to the reburning gas pipeline (10). 13. The boiler combustion system according to claim 12, characterized in that, the reburning gas burner (9) is arranged above the main combustion device. 14. The boiler combustion system according to claim 12, characterized in that, the reburning gas pipeline (10) is divided into two paths after being drawn out from the pyrolysis subsystem, and one path enters one side of the boiler (11) The reburning gas burner (9), another way enters the reburning gas burner (9) on the other side of the boiler (11). 15. The boiler combustion system according to claim 12, characterized in that, the boiler combustion system also includes a semi-coke burner (14), and the semi-coke burner (14) is used for desulfurization and The semi-cokes processed are dried. 16. The boiler combustion system according to claim 15, characterized in that, the semi-coke burner (14) is arranged below the reburning gas burner (9) and above the main combustion device. 17. The boiler combustion system according to claim 12, characterized in that, the boiler combustion system further comprises an overfired air burner (13), and the overfired air burner (13) is arranged at the combustion chamber of the reburned gas The top of the device (9) is used to ensure that the combustibles in the boiler (11) are burned out. 18. The boiler combustion system according to claim 12, characterized in that, the main combustion device includes an upper burner (15), a middle burner (16) and a lower burner (17), for entering into the boiler ( 11) The fuel is subjected to staged combustion.