CN107998818A - The inert gas protection system and method for activated carbon adsorber - Google Patents

Abstract

The inert gas protection system of the activated carbon adsorption tower includes an adsorption tower. According to the flow direction of the flue gas, the lower part of the adsorption tower is provided with a flue gas inlet, and the upper part of the other side of the adsorption tower is provided with a flue gas outlet. It is characterized in that: the flue gas of the adsorption tower There are double baffle doors in the entrance, and a single baffle door in the flue gas outlet of the adsorption tower. A first pipe is connected to the bottom of the adsorption tower to supply inert gas. The end of the first pipe is provided with a first valve. , the front end of the second pipeline is connected to the first pipeline and the rear end of the second pipeline communicates with the space between the front and rear two baffle doors of the double baffle door, the second pipeline is provided with a second valve, and the third pipeline The front end is connected to the first pipe and the connection point is located between the second pipe and the first valve, while the rear end of the third pipe communicates with the downstream space of the double baffle door of the flue gas inlet. Three valves, the fourth pipeline communicates with the third pipeline at the downstream position of the third valve, and the fourth pipeline is provided with a fourth valve.

Description

Inert gas protection system and method for activated carbon adsorption tower

technical field

The present invention relates to the inert gas protection system of the activated carbon adsorption tower in the flue gas purification system of iron ore sintering machine, more specifically, relates to the flue gas purification system (being flue gas adsorption and Analysis system) realizes the system of inert gas protection, and the inert gas protection method of activated carbon adsorption tower.

Background technique

Activated carbon method for flue gas treatment technology has a history of more than 50 years of research and application, and the early technology research and application are mainly concentrated in Germany, Japan, the United States and other countries. Germany's BF company began to develop Reinluft desulfurization technology in 1957 (now DMT company), Japan began to study activated carbon desulfurization in the mid-1960s, and Germany's Lugi Company also carried out water-washed regenerated activated carbon flue gas desulfurization earlier The study of craftsmanship. With the development and maturity of activated carbon flue gas desulfurization technology in foreign countries, some representative ones such as BF method, Reinluft method and Lurgi method in Germany; Japanese legislation and Sumitomo method in Japan; Westraco method in the United States have emerged.

For industrial flue gas, especially sintering machine flue gas in the iron and steel industry, it is ideal to use desulfurization and denitrification devices and processes including activated carbon adsorption towers and desorption towers. In the desulfurization and denitrification devices including activated carbon adsorption tower and desorption tower (or regeneration tower), the activated carbon adsorption tower is used for adsorption of sulfur oxides, nitrogen, and Pollutants including oxides and dioxins, while the desorption tower is used for thermal regeneration of activated carbon.

Activated carbon desulfurization has the advantages of high desulfurization rate, simultaneous denitrification, dioxin removal, dust removal, and no waste water and residue generation. It is a very promising flue gas purification method. Activated carbon can be regenerated at high temperature. When the temperature is higher than 350°C, pollutants such as sulfur oxides, nitrogen oxides, and dioxins adsorbed on the activated carbon will be quickly decomposed or decomposed (sulfur dioxide is decomposed, nitrogen oxides and dioxins English is decomposed). And as the temperature increases, the regeneration speed of activated carbon is further accelerated, and the regeneration time is shortened. It is preferable to generally control the regeneration temperature of activated carbon in the desorption tower to be approximately equal to 430 ° C. Therefore, the ideal desorption temperature (or regeneration temperature) is, for example, at 390 In the range of -450°C, more preferably in the range of 400-440°C.

In the traditional activated carbon desulfurization process, the flue gas is introduced into the adsorption tower by the booster fan, and the mixed gas of ammonia and air is sprayed into the tower inlet to improve the removal efficiency of _NOx , and the purified flue gas enters the sintering main chimney for discharge. . Activated carbon is added into the adsorption tower from the top of the tower, and moves downward under the action of gravity and the discharge device at the bottom of the tower. The activated carbon from the desorption tower is transported to the adsorption tower by the activated carbon conveyor, and the activated carbon saturated with adsorbed pollutants in the adsorption tower is discharged from the bottom, and the discharged activated carbon is transported to the desorption tower by the activated carbon conveyor for regeneration of activated carbon.

Activated carbon flue gas purification technology has the characteristics of simultaneous desulfurization and denitrification, realization of by-product recycling, recyclable adsorbent, high desulfurization and denitrification efficiency, etc. It is a very promising integrated desulfurization and denitrification technology. In the desulfurization and denitrification devices including activated carbon adsorption tower and desorption tower (or regeneration tower), the activated carbon adsorption tower is used for adsorption of sulfur oxides, nitrogen, and Pollutants including oxides and dioxins, while the desorption tower is used for thermal regeneration of activated carbon.

Activated carbon flue gas purification technology has the function of simultaneous desulfurization and denitrification. The main equipment included in this process includes adsorption tower, regeneration tower and activated carbon conveying device.

The role of the desorption tower is to release the _SO2 adsorbed by the activated carbon. At the same time, at a temperature above 400°C and a certain residence time, dioxins can be decomposed by more than 80%. The activated carbon can be reused after cooling and screening. The released SO ₂ can be used to make sulfuric acid, etc., and the activated carbon after the analysis is sent to the adsorption tower through the conveying device for reuse to adsorb SO ₂ and NO _X.

In the adsorption tower and the desorption tower, NO _X reacts with ammonia such as SCR and SNCR, thereby removing NO _X . The dust is adsorbed by the activated carbon when passing through the adsorption tower, separated by the vibrating screen at the bottom of the desorption tower, and the activated carbon powder under the screen is sent to the ash bin, and then sent to the blast furnace or sintered as fuel.

The iron and steel industry has made important contributions to the development of my country's industrialization and urbanization, but at the same time, my country's iron and steel industry has a low level of environmental protection and high pollutant emissions per unit of output, which has seriously restricted the improvement of the overall competitiveness of the iron and steel industry. In order to control the discharge of pollutants, the Ministry of Environmental Protection of the People's Republic of China has formulated the "Steel Sintering and Pelletizing Industry Air Pollutant Emission Standards", pointing out that since January 1, 2015, the existing iron and steel enterprises sintering and pelletizing will implement the following air pollutant emission limits : SO ₂ 200mg/m ³ , NOx 300mg/m ³ , dioxins 0.5ng-TEG/m ³ . It can be seen that the air pollution control in the iron and steel industry has been upgraded from the original dust removal and desulfurization to the coordinated control of SO ₂ -NOx-dioxins and other pollutants. At present, domestic desulfurization technology tends to be mature, while denitrification and dioxin removal are still in their infancy. Domestic Shanghai Kesulfur Co., Ltd. has adopted active coke technology in coal-fired boilers and non-ferrous smelting industries, and its structure and principle are consistent with those of Sumitomo.

Activated carbon (coke) sintering flue gas purification technology is a resource-based dry flue gas treatment technology, which has the functions of water saving, desulfurization, denitrification, dioxin removal, heavy metal removal, dust removal and other trace harmful flue gas components ( Such as HCl, HF, SO _{3 ,} etc.), and at the same time, it can recover sulfur resources that are in short supply in China (high-concentration SO ₂ can be used to prepare concentrated sulfuric acid, etc.).

However, activated carbon is a flammable substance. During the flue gas purification process, due to the unsmooth feeding of the activated carbon, the material accumulates in the tower, the reaction heat cannot be released in time, or the temperature of the flue gas at the inlet of the adsorption tower is not properly controlled, which may lead to adsorption. The activated carbon in the tower has a high temperature phenomenon, and even burns.

After the adsorption tower is at high temperature, the traditional inert gas protection method is to directly feed nitrogen into the tower, without considering the flow state of the inert gas in the tower and the high temperature prevention measures, and the protection effect is not particularly obvious.

In order to ensure the safe operation of the system, the present application proposes an inert gas protection system and method.

Contents of the invention

The purpose of the present invention is to provide an inert gas protection system for an activated carbon adsorption tower.

According to the present invention, an inert gas protection system for an activated carbon adsorption tower is provided, which includes an adsorption tower. According to the flow direction of the flue gas, a flue gas inlet is provided at the lower part of one side of the adsorption tower, and a flue gas outlet is provided at the upper part of the other side of the adsorption tower. The flue gas inlet of the adsorption tower is provided with double baffle doors. The flue gas outlet of the adsorption tower is provided with a single baffle door. A first pipeline is connected to the bottom of the adsorption tower. The end section of the first pipeline is provided with a first valve. The front end of the second pipeline is connected with the first pipeline and the rear end of the second pipeline communicates with the space between the front and rear two baffle doors of the double baffle door. The second pipeline is provided with a second valve. The front end of the third pipeline is connected to the first pipeline and the connection point is located between the second pipeline and the first valve. And the rear end of the third pipe communicates with the downstream space of the double baffle door of the flue gas inlet. The third pipeline is provided with a third valve. The fourth pipe communicates with the third pipe at a position downstream of the third valve. The fourth pipeline is provided with a fourth valve.

Preferably, the above system further includes a temperature monitor, which is used to monitor the temperature in the adsorption tower.

Preferably, the upstream end of the first conduit is connected to an inert gas supply conduit or an inert gas supply source. Preferably, the inert gas is one of nitrogen, helium or argon, more preferably nitrogen.

Preferably, the upstream end of the fourth pipeline is connected to an ammonia gas supply pipeline or an ammonia gas supply source.

Preferably, the temperature detection probe of the temperature detector penetrates the side wall of the adsorption tower and extends into the space of the adsorption tower; preferably, the temperature detection probe is an infrared detection type temperature detector or a thermocouple type temperature detector.

According to the present invention, also provide a kind of inert gas protection method of activated carbon adsorption tower, this method comprises the following steps:

1) The adsorption tower system is operating normally, and the temperature monitor monitors the temperature inside the adsorption tower in real time;

2) Both the double baffle door and the single baffle door are opened, and the flue gas enters the adsorption tower from the flue gas inlet and is discharged from the flue gas outlet;

3) The fourth valve is opened, ammonia gas is passed into the adsorption tower through the fourth pipeline, and the first valve, the second valve and the third valve are closed at the same time, and the temperature monitor shows that the temperature in the adsorption tower is <150°C;

4) When the temperature inside the tower is <150°C, the adsorption tower system operates normally, but when the temperature inside the tower is ≥150°C, according to the specific temperature displayed by the temperature monitor, the double baffle door, single baffle door and each valve Do the corresponding operation.

Preferably, when the temperature monitor shows that the temperature in the adsorption tower is ≥150° C. and <160° C., the operation of step 4) is: the first valve is opened, and the inert gas is introduced into the bottom of the tower through the first pipeline.

Preferably, when the temperature monitor shows that the temperature in the adsorption tower is ≥160°C, the operation of step 4) is specifically:

Both the double baffle door and the single baffle door are closed to cut off the flue gas. The fourth valve is closed to stop the introduction of ammonia gas into the tower. Inert gas is introduced into the space between the doors to block oxygen, the third valve is opened, and inert gas is introduced into the adsorption tower through the third pipeline; preferably, while opening the second valve and the third valve, the first The valve is opened, and the inert gas is introduced into the bottom of the tower through the first pipeline.

Preferably, the inert gas is one of nitrogen, helium or argon, preferably nitrogen.

In this application, generally speaking, the tower height of the adsorption tower is, for example, 8-50m, preferably 10-48m, preferably 13-45m, preferably 15-40m, more preferably 18-35m. The tower height of the adsorption tower refers to the height from the activated carbon outlet at the bottom of the adsorption tower to the activated carbon inlet at the top of the adsorption tower, that is, the height of the main structure of the tower.

In the present invention, there is no special requirement for the desorption tower, and all desorption towers of the prior art can be used in the present invention. Preferably, the desorption tower is a shell-and-tube vertical desorption tower, in which the activated carbon is input from the top of the tower, flows down through the tube side, and then reaches the bottom of the tower, while the heating gas flows through the shell side, and the heating gas enters from one side of the tower , exchange heat with the activated carbon flowing through the tube side to cool down, and then output from the other side of the tower. In the present invention, there is no special requirement for the desorption tower, and all desorption towers of the prior art can be used in the present invention. Preferably, the desorption tower is a shell-and-tube type (or shell-and-tube) vertical desorption tower, wherein the activated carbon is input from the top of the tower, flows down through the tube side of the upper heating zone, and then reaches an upper heating zone and a lower cooling zone. A buffer space between them, then flows through the tube side of the lower cooling zone, and then reaches the bottom of the tower, while the heating gas (or high-temperature hot air) flows through the shell side of the heating zone, and the heating gas (400-450 ° C) flows from the desorption tower It enters into one side of the heating zone of the tower, conducts indirect heat exchange with the activated carbon flowing through the tube side of the heating zone to cool down, and then outputs from the other side of the heating zone of the tower. The cooling air enters from one side of the cooling zone of the desorption tower, and conducts indirect heat exchange with the decomposed and regenerated activated carbon flowing through the tube side of the cooling zone. After the indirect heat exchange, the cooling air is heated up to 90-130°C (eg about 100°C).

In general, the desorption tower used in the present invention usually has a tower height of 10-45m, preferably 15-40m, more preferably 20-35m. The desorption column generally has a main body cross-sectional area of 6-100 m2, preferably 8-50 m2, more preferably 10-30 m2, further preferably 15-20 m2.

"Resolution" and "regeneration" are used interchangeably in this application.

Advantages of the present invention:

The system of the invention can make the inert gas flow regularly in the tower and achieve the best cooling or fire extinguishing effect.

Description of drawings

Fig. 1 is the schematic diagram of the inert gas protection system of activated carbon adsorption tower of the present invention.

Reference signs:

Reference signs: 1: adsorption tower; 2: flue gas inlet; 3: flue gas outlet; 4: double baffle door; 5: single baffle door; 6: first valve; 7: second valve; 8: second Three valves; 9: fourth valve; 10: temperature monitor; L1: first pipeline; L2: second pipeline; L3: third pipeline; L4: fourth pipeline.

Detailed ways

The purpose of the present invention is to provide an inert gas protection system for an activated carbon adsorption tower.

According to the present invention, an inert gas protection system for an activated carbon adsorption tower is provided, which includes an adsorption tower 1. According to the flue gas flow direction, a flue gas inlet 2 is provided at the lower part of one side of the adsorption tower 1, and a flue gas inlet is provided at the upper part of the other side of the adsorption tower 1. The outlet 3 is characterized in that: the flue gas inlet 2 of the adsorption tower 1 is provided with a double baffle door 4, the flue gas outlet 3 of the adsorption tower 1 is provided with a single baffle door 5, and the tower bottom of the adsorption tower 1 is connected with The first pipeline L1, the end section of the first pipeline L1 is provided with a first valve 6, the front end of the second pipeline L2 is connected with the first pipeline L1 and the rear end of the second pipeline L2 is connected with the front and back of the double baffle door 4 The space between the baffle doors is connected, the second pipeline L2 is provided with a second valve 7, the front end of the third pipeline L3 is connected to the first pipeline L1 and the connection point is located between the second pipeline L2 and the first valve 6 , and the rear end of the third pipeline L3 communicates with the downstream space of the double baffle door 4 of the flue gas inlet 2, the third pipeline L3 is provided with a third valve 8, and the fourth pipeline L4 is connected to the downstream position of the third valve 8. The third pipeline L3 is connected, and the fourth pipeline L4 is provided with a fourth valve 9 .

Preferably, the above system further includes a temperature monitor 10 for monitoring the temperature in the adsorption tower 1 .

Preferably, the upstream end of the first pipeline L1 is connected to an inert gas supply pipeline or an inert gas supply source; preferably, the inert gas is one of nitrogen, helium or argon, more preferably nitrogen.

Preferably, the upstream end of the fourth pipeline L4 is connected to an ammonia gas supply pipeline or an ammonia gas supply source.

Preferably, the temperature detection probe of the temperature detector 10 penetrates the side wall of the adsorption tower and extends into the space of the adsorption tower; preferably, the temperature detection probe is an infrared detection type temperature detector or a thermocouple type temperature detector.

According to the present invention, also provide a kind of inert gas protection method of activated carbon adsorption tower, this method comprises the following steps:

1) The adsorption tower system is in normal operation, and the temperature monitor 10 monitors the temperature in the adsorption tower 1 in real time;

2) Both the double baffle door 4 and the single baffle door 5 are opened, and the flue gas enters the adsorption tower 1 from the flue gas inlet 2 and is discharged from the flue gas outlet 3;

3) The fourth valve 9 is opened, and the ammonia gas is passed into the adsorption tower 1 through the fourth pipeline L4, and the first valve 6, the second valve 7 and the third valve 8 are closed at the same time, and the temperature monitor 10 shows that in the adsorption tower 1 Temperature <150°C;

4) When the temperature inside the tower is <150°C, the adsorption tower system operates normally; however, when the temperature inside the tower is ≥150°C, according to the specific temperature displayed by the temperature monitor 10, the double baffle door 4 and the single baffle door 5 And the corresponding operation of each valve.

Preferably, when the temperature monitor 10 shows that the temperature in the adsorption tower 1 is ≥150°C and <160°C, the operation of step 4 is as follows: the first valve 6 is opened, and the inert gas is introduced into the bottom of the tower through the first pipeline L1.

Preferably, when the temperature monitor 10 shows that the temperature in the adsorption tower 1 is ≥160°C, the operation of step 4 is specifically:

Both the double baffle door 4 and the single baffle door 5 are closed to cut off the flue gas. The fourth valve 9 is closed to stop feeding ammonia gas into the tower. Inert gas is passed into the space between the front and rear two baffle doors of the front and back, oxygen is cut off, the third valve 8 is opened, and the inert gas is passed into the adsorption tower 1 through the third pipeline L3; preferably, after opening the second valve 7 and the third valve 8, the first valve 6 is opened, and the inert gas is introduced into the bottom of the tower through the first pipeline L1.

Preferably, the inert gas is one of nitrogen, helium or argon, preferably nitrogen.

When the flue gas purification system is in normal operation, both the double baffle door 4 and the single baffle door 5 are opened to allow the flue gas to pass through the adsorption tower 1 smoothly; the fourth valve 9 is opened to inject ammonia gas into the tower for denitrification; The first valve 6, the second valve 7 and the third valve 8 are closed. At this time, the temperature monitor shows that the temperature in the adsorption tower is <150°C.

When the temperature in the tower is greater than or equal to 150°C, the first valve 6 is opened, and nitrogen is fed into the bottom of the tower. Reason: The activated carbon at the bottom of the tower is not in contact with the flue gas, that is to say, the activated carbon at the bottom of the tower cannot release heat to the flue gas. If the temperature in the tower has reached 150°C, the temperature will be higher when the activated carbon is fed to the bottom of the tower. The activated carbon at the bottom of the tower is directly in contact with the atmosphere after being discharged through the rotary valve. In order to prevent high temperature or even fire, an inert gas is introduced into the bottom of the tower to isolate the air and reduce the temperature of the activated carbon.

When the temperature in the tower is ≥160°C, the double baffle door 4 and the single baffle door 5 are closed to cut off the flue gas; the fourth valve 9 is closed to stop feeding ammonia gas into the tower, which is an explosive gas; the second The valve 7 is opened, and the inert gas is passed into the double baffle door to block the oxygen; the third valve 8 is opened, and the inert gas is injected into the inlet of the adsorption tower through the original ammonia injection port. At this time, the inert gas passes through the activated carbon bed from the inlet to the outlet along the running direction of the original flue gas, and passes through the activated carbon bed in countercurrent to the running direction of the activated carbon from bottom to top, thus realizing the all-round protection of the activated carbon bed. Utilizing the air leakage of the single baffle door at the outlet of the adsorption tower, the inert gas is discharged through the single baffle door, so as to ensure that the pressure in the adsorption tower will not be too high.

The system of the invention can make the inert gas flow regularly in the tower and achieve the best cooling or fire extinguishing effect.

Claims (9)

1. The inert gas protection system of the activated carbon adsorption tower, which includes the adsorption tower (1), according to the flue gas flow direction, the lower part of the adsorption tower (1) is provided with a flue gas inlet (2), and the other side of the adsorption tower (1) The upper part is provided with a flue gas outlet (3), which is characterized in that: the flue gas inlet (2) of the adsorption tower (1) is provided with double baffle doors (4), and the flue gas outlet (3) of the adsorption tower (1) is A single baffle door (5) is provided, the first pipeline (L1) is connected at the bottom of the adsorption tower (1), the end of the first pipeline (L1) is provided with a first valve (6), and the second pipeline ( The front end of L2) is connected to the first pipe (L1) and the rear end of the second pipe (L2) communicates with the space between the front and rear two baffle doors of the double baffle door (4). On the second pipe (L2) There is a second valve (7), the front end of the third pipeline (L3) is connected to the first pipeline (L1) and the connection point is between the second pipeline (L2) and the first valve (6), and the third The rear end of the pipe (L3) communicates with the downstream space of the double baffle door (4) of the flue gas inlet (2), the third pipe (L3) is provided with a third valve (8), and the fourth pipe (L4) is The downstream position of the third valve (8) communicates with the third pipeline (L3), and the fourth pipeline (L4) is provided with a fourth valve (9). 2. The inert gas protection system according to claim 1, characterized in that: the system further comprises a temperature monitor (10), and the temperature monitor (10) is used to monitor the temperature in the adsorption tower (1). 3. The inert gas protection system according to claim 1 or 2, characterized in that: the upstream end of the first pipeline (L1) is connected to an inert gas supply pipeline or an inert gas supply source; preferably, the inert gas is nitrogen, helium Or one of argon, more preferably nitrogen. 4. The inert gas protection system according to any one of claims 1-3, characterized in that: the upstream end of the fourth pipeline (L4) is connected to an ammonia gas supply pipeline or an ammonia gas supply source. 5. system according to claim 2, wherein the temperature detection probe of temperature detector (10) penetrates adsorption tower side wall and stretches in the adsorption tower space; Preferably, temperature detection probe is the temperature detector of infrared detection formula or thermocouple-type temperature detectors. 6. An inert gas protection method for an activated carbon adsorption tower, the method comprising the following steps: 1) The adsorption tower system operates normally, and the temperature monitor (10) monitors the temperature in the adsorption tower (1) in real time; 2) Both the double baffle door (4) and the single baffle door (5) are opened, and the flue gas enters the adsorption tower (1) from the flue gas inlet (2) and is discharged from the flue gas outlet (3); 3) The fourth valve (9) is opened, and the ammonia gas is passed into the adsorption tower (1) through the fourth pipeline (L4), while the first valve (6), the second valve (7) and the third valve (8) are closed , now the temperature monitor (10) shows that the temperature in the adsorption tower (1) is <150°C; 4) When the temperature inside the tower is <150°C, the adsorption tower system operates normally; however, when the temperature inside the tower is ≥150°C, according to the specific temperature displayed by the temperature monitor (10), the double baffle door (4), single Baffle door (5) and each valve carry out corresponding operation. 7. The method of using the inert gas protection system according to claim 6, characterized in that: when the temperature monitor (10) shows that the temperature in the adsorption tower (1) is ≥150°C and <160°C, the operation of step 4) is specific For: the first valve (6) is opened, and the inert gas is introduced into the bottom of the tower through the first pipeline (L1). 8. The method according to claim 6 or 7, characterized in that: when the temperature monitor (10) shows that the temperature in the adsorption tower (1) is ≥160°C, the operation of step 4) is specifically: Both the double baffle door (4) and the single baffle door (5) are closed to cut off the flue gas, the fourth valve (9) is closed to stop feeding ammonia gas into the tower, the second valve (7) is opened, and through the second The pipeline (L2) feeds inert gas into the space between the front and rear two baffle doors of the double baffle door (4) to block oxygen, the third valve (8) is opened, and the air is sent to the adsorption tower through the third pipeline (L3). (1) Inert gas is introduced into the interior; preferably, while the second valve (7) and the third valve (8) are opened, the first valve (6) is opened, and the gas is discharged into the bottom of the tower via the first pipeline (L1). Pass inert gas. 9. The method according to any one of claims 6-8, characterized in that: the inert gas is one of nitrogen, helium or argon, preferably nitrogen.