CN201239608Y - Integrated system for simultaneous desulfuration and denitration using semidry process - Google Patents

Abstract

The utility model discloses a semi-dry integration system which can carry out desulfuration and denitration at the same time. A venturi (4-1) is arranged at the bottom part of a desulfuration and denitration reaction tower (4); a quicklime slaking feeding device (1) is connected to the middle part of the desulfuration and denitration reaction tower (4) through a feeding pipe (5); a flue gas dust removing and oxidation device (2) is connected to the bottom part of the desulfuration and denitration reaction tower (4) through a flue gas deliver pipe (6); a flue gas discharge device (3) is connected to the upper part of the desulfuration and denitration reaction tower (4) through a flue gas deliver pipe (7); and the desulfuration and denitration reaction tower (4) is connected with a water pump (9) and a process water tank (10) in sequence through a water deliver pipe (8). The utility model can eliminate various contaminants such as SO2, NOx and the like, and meanwhile, has the advantages of simple technique, simplified system, small occupied area, low investment and running cost, low water consumption and utilizable byproduct. Furthermore, the whole system does not need anti-corrosion treatment.

Description

Simultaneous semi-dry desulfurization and denitrification integrated system

technical field

The utility model belongs to a flue gas desulfurization and denitrification purification system, in particular, it is a semi-dry simultaneous desulfurization and denitrification integrated system.

Background technique

my country is a country that uses coal as the main energy source, and coal-fired power generation is one of the most important ways of coal utilization in my country. According to my country's national conditions, coal-fired power generation will dominate in the 21st century. Among the many air pollutants emitted by coal-fired thermal power units, SO ₂ , NOx and dust are more harmful to the environment and are also the main pollutants to be controlled. With the progress of society and the development of economy, the pollution of thermal power plants to the atmospheric environment has been widely concerned by people. Therefore, it is a severe challenge for the sustainable development of my country's energy field to effectively reduce pollutant emissions and improve the impact on the environment.

At present, the existing flue gas purification technologies are all independently researched and developed for desulfurization (removal of SO ₂ in the flue gas), denitrification, and removal of dust in the flue gas. systems and processes. If you want to remove the pollutants in the flue gas at the same time to meet the allowable emission standards, you need at least two sets of independent removal systems and process flows. It is expensive, and there are still many problems in how to rationally organize these independent systems to achieve higher flue gas purification efficiency.

Problems existing in existing desulfurization and denitrification technologies:

Wet flue gas desulfurization technology mainly has the disadvantages of large investment, large power consumption, large floor area, complex equipment, high operating costs and technical requirements.

Compared with wet desulfurization technology, semi-dry desulfurization technology has the advantages of less investment, small footprint, low operating cost, simple equipment, convenient maintenance, and no need for reheating flue gas, but there are high calcium-sulfur ratios, low desulfurization efficiency, The by-products cannot be commercialized and other shortcomings.

Although the SCR or SNCR method in the flue gas denitrification technology can achieve high denitrification efficiency and meet very strict environmental protection standards, its denitrification system is huge, the equipment is complex, and the investment and operation costs are high.

At present, the patents related to this topic include: the Chinese invention patent specification with the application number 200710052129.7 proposes a wet flue gas cleaning process and system for simultaneous desulfurization and denitrification. Since the system actually uses a wet method, the water consumption of the entire process is very high. Large, it is very difficult for flue gas desulfurization in water-deficient areas, and the promotion of this technology is not used; and the price of absorbent-ammonia water is relatively high, and the cost of raw materials is high. The Chinese invention patent specification with the application number 03125332.6 proposes a simultaneous desulfurization and denitrification dry flue gas cleaning process and its system. In fact, the system is equipped with a desulfurization system and a denitrification system respectively. The system composition is still relatively complicated, and the integration goal has not been achieved. .

Utility model content

The technical problem to be solved by the utility model is to provide an integrated system for simultaneous desulfurization and denitrification in a reaction tower by semi-dry method.

The technical scheme of the utility model is as follows: a semi-dry simultaneous desulfurization and denitrification integrated system, including quicklime slaking and feeding device, flue gas dust removal and oxidation device and flue gas discharge device, the key lies in: the quicklime slaking and feeding device, A desulfurization and denitrification reaction tower is connected between the flue gas dust removal and oxidation device and the flue gas discharge device through pipelines. Venturi is installed at the bottom of the desulfurization and denitrification reaction tower. The middle part is connected, the output end of the flue gas dedusting and oxidation device is connected with the bottom of the desulfurization and denitration reaction tower through the smoke delivery pipe, and the input end of the flue gas discharge device is connected with the upper part of the desulfurization and denitration reaction tower through the smoke exhaust pipe; the desulfurization and denitration reaction tower A water pump and a process water tank are sequentially connected through a water delivery pipe, and the connections between the water delivery pipe and the feed pipe and the desulfurization and denitration reaction tower are located above the Venturi.

The above quicklime slaking feeding device is composed of a quicklime bin, a first weighing feeder, a conveyor belt, a digester, a slaked lime bin and a second weighing feeder, and the first weighing feeder is set at the lower end of the quicklime bin, The conveyor belt below the first weighing feeder is connected to the inlet of the digester, the discharge end of the digester is connected to the top of the slaked lime bin through a pipeline, and the second weighing feeder at the lower end of the slaked lime bin is connected to a feeding pipe; The process water tank communicates with the inlet end of the digester through a pipeline through a digester water pump. The process water tank not only supplies water to the desulfurization and denitrification reaction tower but also supplies water to the digester.

The above-mentioned flue gas dust removal and oxidation device is composed of a pre-dust collector connected to a flue gas oxidation device through a pipeline, and the flue gas oxidation device is connected to a smoke delivery pipe.

The above-mentioned flue gas discharge device is composed of an electrostatic precipitator, a booster fan and a chimney. The electrostatic precipitator, booster fan and chimney are connected by pipelines in turn, and the inlet of the electrostatic precipitator is connected to a smoke exhaust pipe. The bottom of the electrostatic precipitator communicates with the lower part of the desulfurization and denitrification reaction tower through a pipe, and the connection between the pipe and the desulfurization and denitration reaction tower is located between the feed pipe and the water delivery pipe and the connection of the desulfurization and denitration reaction tower. Most of the ash collected by the electrostatic precipitator returns to the absorption tower through the pipeline connecting the bottom of the electrostatic precipitator with the lower part of the desulfurization and denitrification reaction tower to continue the reaction.

Beneficial effect:

(1) The system integration design of the utility model can remove various pollutants such as SO ₂ and NOx at the same time; the process is simple, the system is simplified, the floor area is small, and the investment and operation costs are low;

(2) The market supply of quicklime or slaked lime, the system removal agent, is sufficient and it is convenient to purchase locally.

(3) The system adopts semi-dry technology, which consumes less water and is especially suitable for use in water-shortage areas;

(4) By-products are available resources;

(5) The removal system can almost completely remove sulfur trioxide in the flue gas, so the whole set of desulfurization device does not need anti-corrosion.

Description of drawings

Fig. 1 is the connection schematic diagram of the present utility model;

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described:

As shown in Figure 1, the utility model semi-dry simultaneous desulfurization and denitrification integrated system is composed of quicklime slaking and feeding device 1, flue gas dust removal and oxidation device 2, flue gas discharge device 3 and desulfurization and denitrification reaction tower 4, etc. There is a desulfurization and denitrification reaction tower 4 between the quicklime slaking and feeding device 1, the flue gas dedusting and oxidation device 2 and the flue gas discharge device 3. The bottom of the desulphurization and denitrification reaction tower 4 is equipped with a Venturi 4-1. The quicklime slaking and feeding device 1 It consists of quicklime bin 1-1, first weighing feeder 1-2, conveyor belt 1-3, digester 1-4, slaked lime bin 1-5 and second weighing feeder 1-6, the quicklime The lower end of the warehouse 1-1 is provided with a first weighing feeder 1-2, and the conveyor belt 1-3 below the first weighing feeder 1-2 is connected with the entrance of the digester 1-4, and the exit of the digester 1-4 is The material end communicates with the top of the slaked lime bin 1-5 through a pipeline, and the second weighing feeder 1-6 at the lower end of the slaked lime bin 1-5 is connected to the feed pipe 5; The inlets of the digesters 1-4 are connected. The quicklime slaking feeding device 1 communicates with the middle part of the desulfurization and denitrification reaction tower 4 through a feeding pipe 5, and the flue gas dust removal and oxidation device 2 is composed of a pre-dust collector 2-1 connected to a flue gas oxidation device 2-2 through a pipeline. The flue gas oxidation device 2-2 is connected to the smoke delivery pipe 6. The flue gas dedusting and oxidation device 2 communicates with the bottom of the desulfurization and denitration reaction tower 4 through the smoke delivery pipe 6, and the flue gas discharge device 3 communicates with the upper part of the desulfurization and denitration reaction tower 4 through the smoke exhaust pipe 7; the desulfurization and denitration reaction tower 4 The water pump 9 and the process water tank 10 are sequentially connected through the water delivery pipe 8 , and the connection between the water delivery pipe 8 and the desulfurization and denitration reaction tower 4 is lower than the connection between the feeding pipe 5 and the desulfurization and denitration reaction tower 4 . The bottom of the electrostatic precipitator 3-1 communicates with the lower part of the desulfurization and denitration reaction tower 4 through a pipeline, and the connection between the pipeline and the desulfurization and denitration reaction tower 4 is located between the feeding pipe 5 and the water delivery pipe 8 and the connection between the desulfurization and denitration reaction tower 4 on the tower wall.

Working principle: The purchased quicklime is sent to the quicklime bin 1-1 by the tanker, and then conveyed to the digester 1-4 by the conveyor belt 1-3, and the quicklime and water are mixed and reacted in the digester 1-4 to produce slaked lime.

The main reaction equation is as follows: CaO+H ₂ O=Ca(OH) ₂

The slaked lime produced by digestion is sent to slaked lime bin 1-5 for use.

The pre-dust collector 2-1 is connected to the flue gas, and the desulfurized flue gas can remove more than 90% of the fly ash in the flue gas through the pre-dust collector 2-1. Next, the flue gas passing through the pre-dust collector 2-1 passes through the flue gas oxidation device 2-2, using air as the atomizing medium, and spraying hydrogen peroxide evenly into the dust-removed flue gas,

The main equations that take place are as follows:

NO+H ₂ O ₂ ＝NO ₂ +H ₂ O

2NO+O ₂ ＝2NO ₂

SO ₂ +H ₂ O ₂ =SO ₃ +H ₂ O

The nitric oxide NO in the flue gas is oxidized to nitrogen dioxide NO ₂ , and the sulfur dioxide SO ₂ is oxidized to sulfur trioxide SO ₃ , which is beneficial to the next step of absorption; the temperature of the flue gas is controlled above 100°C in order to make The oxidation reaction in flue gas is easier to carry out,

Increase oxidation rate. Generally speaking, the flue gas from the boiler enters the bottom of the reaction tower after being dedusted by the pre-dust collector. The temperature of the flue gas is generally 120-160°C, which can fully meet the system requirements. Then, the oxidized flue gas enters the tower from the bottom of the desulfurization and denitrification reaction tower 4, accelerates to a flow velocity of 40-50 m/s through the Venturi 4-1 in the tower, and then mixes and disturbs with the absorbent slaked lime to form a high-dust amount of reaction bed,

The main reactions that take place in the desulfurization and denitrification reaction tower 4 are as follows:

Ca(OH) ₂ +H ₂ O+SO ₂ +1/2H ₂ O＝CaSO4*2H ₂ O

Ca(OH) ₂ +H ₂ O+NO ₂ ＝Ca(NO ₃ ) ₂ +2H ₂ O

Ca(OH) ₂ +2HCl=CaCl ₂ +2H ₂ O

Ca(OH) ₂ +2HF＝CaF ₂ +2H ₂ O

Here, sulfur dioxide and nitrogen dioxide in the flue gas react with the absorbent to generate calcium sulfite and calcium nitrate. At the same time, the water pump 9 in the process water tank 10 sprays atomized water into the reaction bed through the water delivery pipe 8 to humidify and cool the flue gas to achieve the best reaction temperature and humidity, which is conducive to absorption. At the same time, calcium sulfite becomes calcium sulfate under the catalysis of nitrogen dioxide.

According to the flow rate of flue gas at the inlet of desulfurization and denitrification reaction tower 4 and the concentration of _SO2 at the inlet, the feeding amount of slaked lime powder can be controlled by adjusting the speed of the ash discharge valve of the Ca(OH) ₂ bin. The SO ₂ concentration at the outlet of the desulfurization and denitrification reaction tower 4 is used as an auxiliary control parameter for checking and accurately adjusting the feeding amount of slaked lime powder, so as to ensure that the required SO ₂ emission concentration is achieved. In this way, even if the working conditions change, the feeding system can adjust the Ca/S ratio in time according to the _SO2 concentration, thereby adjusting the lime feeding amount.

Finally, the flue gas from which sulfur dioxide has been removed is mixed with high-concentration solid reaction products and discharged from the top of the desulfurization and denitrification reaction tower 4, and enters the electrostatic precipitator 3-1, and most of the ash collected by the electrostatic precipitator 3-1 is subjected to electrostatic precipitator The device 3-1 returns to the desulfurization and denitrification reaction tower 4 through the pipeline communicating with the lower part of the desulfurization and denitration reaction tower 4 at the bottom to continue the reaction.

A small part of the desulfurized ash is sent to the desulfurized ash storage 12 as a desulfurized by-product. The flue gas purified by the electrostatic precipitator 3-1 is sent to the chimney 3-3 by the booster fan 3-2 for discharge. The use of electric dust collector or bag filter for dust removal here has an equivalent effect.

System removal effect:

1 The dust removal efficiency of the system is not less than 99%;

2 The SO ₂ removal efficiency of the system is not less than 85%;

3 NOx removal rate is not lower than 40%; Hg removal rate is not lower than 70%;

4 It also has a certain removal effect on HCl and VOCs in flue gas.

Claims (5)

1. A semi-dry simultaneous desulfurization and denitrification integrated system, comprising a quicklime slaking feeding device (1), a flue gas dust removal and oxidation device (2) and a flue gas discharge device (3), characterized in that: the quicklime slaking feeder A desulfurization and denitration reaction tower (4) is connected through pipelines between the feed device (1), the flue gas dedusting and oxidation device (2) and the flue gas discharge device (3), and a venturi ( 4-1), the output end of the quicklime slaking and feeding device (1) communicates with the middle part of the desulfurization and denitrification reaction tower (4) through the feeding pipe (5), and the output end of the flue gas dedusting and oxidation device (2) passes through The smoke delivery pipe (6) communicates with the bottom of the desulfurization and denitration reaction tower (4), and the input end of the flue gas discharge device (3) communicates with the upper part of the desulfurization and denitration reaction tower (4) through the smoke exhaust pipe (7); The desulfurization and denitrification reaction tower (4) is sequentially connected to the water pump (9) and the process water tank (10) through the water delivery pipe (8), and the connection between the water delivery pipe (8) and the feeding pipe (5) and the desulfurization and denitration reaction tower (4) Both are located above the Venturi (4-1). 2. The semi-dry simultaneous desulfurization and denitrification integrated system according to claim 1, characterized in that: the quicklime slaking and feeding device (1) includes a quicklime bin (1-1), a first weighing feeder (1 -2), conveyor belt (1-3), digester (1-4), slaked lime bin (1-5) and second weighing feeder (1-6), the lower end of the quicklime bin (1-1) The first weighing feeder (1-2) is set, and the conveyor belt (1-3) below the first weighing feeder (1-2) is connected to the entrance of the digester (1-4), and the digester ( 1-4) The discharge end communicates with the top of the slaked lime bin (1-5) through a pipeline, and the second weighing feeder (1-6) at the lower end of the slaked lime bin (1-5) is connected to the feed pipe (5); The water required for the reaction in the digester (1-4) is supplied from the process water tank (10) through the digester water pump (11) through pipelines. 3. The semi-dry simultaneous desulfurization and denitrification integrated system according to claim 1, characterized in that: the flue gas dust removal and oxidation device (2) is connected to the flue gas oxidation device (2) by a pre-dust collector (2-1) through a pipeline -2) Composition, the flue gas oxidation device (2-2) is connected to the smoke delivery pipe (6). 4. The semi-dry simultaneous desulfurization and denitrification integrated system according to claim 1, characterized in that: the flue gas discharge device (3) consists of an electrostatic precipitator (3-1), a booster fan (3-2) and The chimney (3-3) is composed of the electrostatic precipitator (3-1), the booster fan (3-2) and the chimney (3-3) which are successively connected by pipelines, and the inlet of the electrostatic precipitator (3-1) Connect the exhaust pipe (7). 5. The semi-dry simultaneous desulfurization and denitrification integrated system according to claim 4, characterized in that: the bottom of the electrostatic precipitator (3-1) communicates with the lower part of the desulfurization and denitrification reaction tower (4) through a pipeline, and the pipeline is connected to the desulfurization and denitrification reaction tower (4). The connection of the denitration reaction tower (4) is located between the feed pipe (5) and the water delivery pipe (8) and the connection of the desulfurization and denitration reaction tower (4).

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