CN204891598U - System for nitrogen oxide and oxysulfide in while desorption flue gas - Google Patents

Abstract

A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas belongs to the technical field of flue gas purification. The system includes a fluidized bed reactor with a dense phase zone, a gas-solid separator, a humidification activator, a return control valve, and a fresh absorbent storage tank; the bottom of the fluidized bed reactor is provided with an incoming flue gas inlet pipe , Spent absorbent discharge pipe and water spray pipe, the upper part is provided with a flue gas outlet, and the interior is provided with a water atomization nozzle. The flue gas outlet is connected to the inlet of the gas-solid separator, the material outlet of the gas-solid separator is connected to the material inlet of the humidification activator; the material outlet of the humidification activator is connected to the fluidized bed reactor. The utility model realizes the purpose of simultaneous desulfurization and denitrification in one reactor, and there is no need to establish two sets of flue gas purification devices because of the difference between sulfur oxides and nitrogen oxides, thereby greatly saving equipment investment and effectively improving the utilization of absorbents rate, and achieved a relatively ideal desulfurization and denitrification effect.

Description

A system for simultaneously removing nitrogen oxides and sulfur oxides from flue gas

technical field

The utility model relates to equipment for desulfurizing and denitrifying flue gas after burning fossil fuels, and belongs to the technical field of flue gas purification.

Background technique

Today, due to the large-scale use of fossil fuels, more than 20 million tons of sulfur oxides (mainly SO2) and more _than 10 million tons of nitrogen oxides (mainly NO) are discharged into the atmosphere every year, causing Serious acid rain pollution. At present, technologies for controlling sulfur dioxide emissions that have been applied on a large scale include limestone-gypsum method and semi-dry flue gas desulfurization technology (spray drying method and flue gas circulating fluidized bed method), which are characterized by high desulfurization efficiency, but Unable to denitrify. Especially for the semi-dry flue gas desulfurization technology, when CaO or Ca(OH) ₂ is used as the absorbent, although the finer the absorbent particles, the higher the reactivity, but the calcium-sulfur molar ratio (relative to the SO ₂ in the inlet flue gas ) actually exceeds 1.5 in order to achieve a higher desulfurization efficiency. The more mature technologies for reducing nitrogen oxide emissions in flue gas include SCR (selective catalytic reduction) and SNCR (selective non-catalytic reduction), both of which use ammonia or urea to reduce nitrogen oxides in flue gas to The advantage of SCR is high denitrification efficiency, but the disadvantage is high cost, especially the cost of catalyst, which is difficult for industrial boiler users to accept, and has high requirements for operation and maintenance, while the cost of SNCR is relatively low, but The denitrification efficiency is also relatively low, and the temperature of the injection point is strict. Both require the reducing agent to be mixed with the flue gas evenly, otherwise part of the reducing agent will escape and cause secondary pollution. The above desulfurization and denitrification technologies implement separate control of sulfur dioxide and nitrogen oxides, and the investment in equipment is relatively large.

Chinese patent document (ZL200910090740.8) proposes a method for simultaneous removal of sulfur oxides and nitrogen oxides in flue gas (200910090740.8). In actual operation, this technology cannot achieve the ideal simultaneous desulfurization and denitrification efficiency. The utilization rate of the absorbent is relatively low, therefore, the technology needs to be improved, perfected and optimized.

Utility model content

The purpose of this utility model is to propose an effective and convenient system for removing nitrogen oxides and sulfur oxides in flue gas at the same time, aiming at realizing the function of simultaneous desulfurization and denitrification in one reactor on the basis of the original technology , in order to further improve the utilization rate of the absorbent, and achieve the purpose of efficient and simultaneous removal of sulfur oxides and nitrogen oxides.

The technical scheme of the utility model is as follows:

A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas, characterized in that: the system includes a fluidized bed reactor, a gas-solid separator, a humidification activator and a fresh absorbent storage tank; There is an air distribution plate inside the fluidized bed reactor, and part of the air distribution plate is a dense phase area and a dilute phase area. agent outlet, the upper part of the fluidized bed reactor is provided with a flue gas outlet; the flue gas outlet is connected to the inlet of the gas-solid separator, and the material outlet of the gas-solid separator is connected to the material inlet of the humidification activator; The material outlet of the activator is connected to the fluidized bed reactor; an atomizing nozzle is arranged in the dilute phase area of the fluidized bed reactor.

Preferably, the gas-solid separator adopts a bag filter.

Preferably, an auger is provided within the humidification activator.

Preferably, a return control valve is provided on the pipeline between the humidification activator and the circulating fluidized bed reactor.

Compared with the prior art, the utility model has the following advantages and prominent effects: ①Compared with the traditional circulating fluidized bed semi-dry flue gas desulfurization technology, the utility model has a promoting effect on the desulfurization process because of the denitrification process. Under the condition of calcium sulfur molar ratio (relative to SO ₂ in the inlet flue gas), the simultaneous desulfurization and denitrification technology of the utility model can achieve higher desulfurization efficiency, and has lower requirements on the relative humidity of the flue gas; more importantly, While achieving high-efficiency desulfurization, NO can also be efficiently removed, achieving the purpose of simultaneous desulfurization and denitrification in one reactor, and it is not necessary to establish two sets of flue gas purification devices because of the difference between sulfur oxides and nitrogen oxides, thus greatly The equipment investment is saved, and the control cost of flue gas pollutant emission is reduced. ②The feature of this utility model is that on the basis of revealing the chemical reaction principle of simultaneous desulfurization and denitrification, according to the characteristics of flue gas components and combined with actual operating experience, the structure of the system has been improved and perfected, such as adding a humidifying activator, By reasonably controlling the process steps and operating parameters, a relatively ideal desulfurization and denitrification effect is achieved. The SO ₂ removal rate can reach more than 90%, and the NO removal rate can reach more than 65%. Within the concentration range of sulfur dioxide and nitrogen oxides in flue gas discharged from conventional industrial boilers or kilns, the emissions of sulfur oxides and nitrogen oxides can meet the national environmental protection requirements. ③ The utility model activates the spent absorbent separated from the gas-solid separator, and returns it to the fluidized bed reactor to participate in desulfurization and denitration reactions, which significantly improves the utilization rate of the absorbent.

Description of drawings

Fig. 1 is system of the present utility model and process flowchart.

In the figure: 1 - incoming flue gas inlet pipe; 2 - fluidized bed reactor; 3 - humidification activator; 4 - fresh absorbent storage tank; 5 - atomized water nozzle; 6 - fluidized bed reactor Outlet flue; 7-gas-solid separator; 8-return material control valve; 9-clean flue gas flue; 10-water or steam pipe; 11-dense phase area; 12-dilute phase area; 13-air distribution plate ; 14-auger; 15-spray pipe; 16-poor absorbent discharge pipe.

Detailed ways

The principle, structure and process of the present utility model will be further described below with the aid of the accompanying drawings.

Fig. 1 is system of the present utility model and process flow diagram, described system comprises fluidized bed reactor 2, gas-solid separator 7, humidifying activator 3 and fresh absorbent storage tank 4; In the fluidized bed reactor An air distribution plate 13 is provided, and the fluidized bed on the top of the air distribution plate is divided into a dense phase area 11 and a dilute phase area 12, and the height of the dense phase area is 5 to 50 cm; The flue gas inlet pipe 1, the spent absorbent discharge pipe 16 and the water spray pipe 15, the upper part of the fluidized bed reactor is provided with a flue gas outlet 6; the flue gas outlet is connected with the inlet of the gas-solid separator 7, and the gas-solid separation The material outlet of the humidification activator is connected with the material inlet of the humidification activator 3; the material outlet of the humidification activator is connected with the fluidized bed reactor through the return control valve 8; the activation medium water or steam is arranged on the humidification activator Interface 10; an atomized water nozzle is provided in the dilute phase area of the fluidized bed reactor. The gas-solid separator adopts a bag filter.

The technological process of the present utility model is as follows:

After the combustion flue gas containing SO ₂ , NO, water vapor, oxygen, carbon dioxide, nitrogen and fly ash is pre-dedusted, the temperature of the flue gas is controlled within the range of 80-150°C by adjusting the water spray volume of the water spray pipe 15, and the flue gas is automatically Channel 1 enters fluidized bed reactor 2, under the condition that O ₂ , SO ₂ , H ₂ O and absorbent exist simultaneously, NO in the flue gas is oxidized to NO ₂ in the dense phase zone of circulating fluidized bed, Then, together with SO ₂ or SO ₃ in the flue gas, it is absorbed and solidified by the absorbent Ca(OH) ₂ , CaO, red mud or their mixture to achieve simultaneous desulfurization and denitrification. _The amount of fresh absorbent entering the system is adjusted according to the molar ratio of SO2 to NO in the flue gas and their respective concentrations. In order to ensure a high desulfurization and denitrification efficiency in the fluidized bed reactor, the atomized water spray volume is adjusted through the atomized water nozzle 5, and the relative humidity of the flue gas at the outlet of the fluidized bed reactor is controlled in the range of 10-60%. The flue gas after desulfurization and denitrification carries solid particles through the outlet flue 6 of the fluidized bed reactor and enters the gas-solid separator 7. The separated solid materials mainly contain CaO or Ca(OH) ₂ or unreacted red mud, and Desulfurization products CaSO ₄ , CaSO ₃ , denitrification products Ca(NO ₃ ) ₂ , Ca(NO ₂ ) ₂ and other substances. In order to improve the utilization rate of the absorbent, the separated solid material and fresh absorbent are activated by water or steam in the humidification activator, and the moisture content of the particles is controlled between 0.5 and 2 by adjusting the amount of water or steam. % range, the activated solid material is directly returned to the dense phase zone of the fluidized bed reactor through the return control valve 8, and re-participates in the reaction process of simultaneous desulfurization and denitrification. By controlling the bed pressure drop in the circulating fluidized bed reactor In order to ensure the denitrification efficiency and avoid excessive fan power consumption caused by excessive resistance, some solid materials can be discharged from the bottom of the fluidized bed or the bottom of the gas-solid separator to maintain the balance of solid materials in the entire system. After passing through the gas-solid separator The flue gas is discharged from the clean flue gas flue 9. In addition, in addition to using traditional CaO or Ca(OH) ₂ as absorbent, the utility model can also use red mud, a bulk waste in the aluminum smelting industry, as absorbent to remove SOx and NOx in flue gas , so as to achieve the purpose of treating waste with waste.

Example 1: using slaked lime as absorbent, SO in the flue gas The volume ratio of NO and ₂ :1, the molar ratio of calcium sulfur to nitrogen (Ca/(S+0.5N)) is 1.3, and the solid material at the outlet of the humidifying activator contains The moisture content is 1.5%, the incoming flue gas temperature is 110°C, the height of the dense phase area in the fluidized bed reactor is about 20cm, the oxygen volume fraction in the flue gas is 5%, the relative humidity of the flue gas at the outlet of the fluidized bed reactor is 50%, and the desulfurization efficiency is 90% % or more, and the denitrification efficiency is more than 65%.

Claims (4)

1. A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas is characterized in that: said system comprises a fluidized bed reactor (2), a gas-solid separator (7), a humidification activator ( 3) and the fresh absorbent storage tank (4); the fluidized bed reactor is provided with an air distribution plate (13), and part of the air distribution plate is a dense phase area (11) and a dilute phase area (12). The height of the zone is 5-50cm; at the bottom of the fluidized bed reactor, there is an incoming flue gas inlet pipe (1), a spent absorbent discharge pipe (16) and a water spray pipe (15), and the upper part of the fluidized bed reactor is provided with There is a flue gas outlet (6); the flue gas outlet is connected to the inlet of the gas-solid separator (7), and the material outlet of the gas-solid separator is connected to the material inlet of the humidification activator (3); the humidification activator The material outlet of the fluidized bed reactor is connected to the fluidized bed reactor; the humidification activator is provided with a water or steam interface (10); and a water atomizing nozzle (5) is provided in the dilute phase area (12) of the fluidized bed reactor. 2. A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas according to claim 1, wherein the gas-solid separator adopts a bag filter. 3. A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas according to claim 1, characterized in that: an auger (14) is arranged in the humidifying activator. 4. A system for simultaneously removing nitrogen oxides and sulfur oxides in flue gas according to claim 1, characterized in that: the pipeline between the humidification activator and the circulating fluidized bed reactor is provided with Feedback control valve (8).