Process and device for treating boron-rich glass kiln exhaust gases

Abstract

The application belongs to the technical field of harmful gas treatment, and particularly relates to a boron-rich glass kiln waste gas treatment process and device. The boron-rich glass kiln flue gas treatment device comprises a first tube-shell heat exchanger, a conditioning pipe, a honeycomb type temperature reducer, a bag type dust collector, a second tube-shell heat exchanger, an SCR denitration tower and a chimney. The tube passage outlet end of the first tube-shell heat exchanger is connected to the inlet end of the conditioning pipe through a first communication pipe. The outlet end of the conditioning pipe is connected to the gas inlet of the honeycomb type temperature reducer through a second communication pipe. The exhaust outlet of the honeycomb type temperature reducer is connected to the inlet end of the bag type dust collector through a third communication pipe. The waste gas treatment process performed by the device can avoid the adhesion of borides in the flue and equipment, and can almost completely remove the borides, particles and harmful gases in the flue gas. Moreover, the process treatment link is simple, the equipment failure rate is low, and the operation consumption is small.

Description

Technical Field

[0001] This invention belongs to the field of harmful gas treatment technology, specifically relating to a waste gas treatment device and process for boron-rich glass kilns, and particularly to a flue gas treatment device and process for medium and high boron glass kilns such as pharmaceutical glass and heat-resistant glass. Background Technology

[0002] Medium and high borosilicate glasses possess excellent chemical stability, a low coefficient of thermal expansion, good thermal shock resistance, and water resistance, and are widely used in precision optoelectronics and pharmaceutical glass packaging. The production of medium and high borosilicate glasses requires the addition of borax in a certain proportion. However, because boron oxide has a melting point of 450℃, it is highly volatile under high-temperature conditions. Calculations show that the volatilization rate of boron oxide in the glass batch is as high as 8.9% to 12.78% at a furnace temperature of 1400℃. After the volatile borosilicates enter the exhaust gas pipeline with the flue gas, they gradually combine with water vapor in the flue gas to form viscous, amorphous borosilicates as the temperature decreases. These amorphous borosilicates not only adhere to the inner wall of the flue gas pipeline, forming deposits, but also adhere to the interior of environmental treatment facilities such as denitrification catalysts and dust collector filter media, severely reducing the treatment efficiency of denitrification and dust removal processes, greatly shortening the service life of environmental treatment equipment. Furthermore, borosilicates released into the atmosphere combine with water vapor to produce acid rain, causing air pollution. Therefore, borates in flue gas must be removed before denitrification.

[0003] Currently, the most common process for treating waste gas from boron-rich glass kilns involves first cooling the flue gas below the boiling point of boron oxide, then mixing in a certain amount of slaked lime to remove borides, HF, etc., followed by dust removal. After dust removal, the flue gas is heated to meet the requirements for SCR denitrification before entering the denitrification tower to remove NO. X Finally, the flue gas is vented to the chimney by an induced draft fan.

[0004] The above-mentioned processes have many shortcomings. First, flue gas cooling is achieved by mixing cold air into the flue, spraying water mist, or using heat exchangers, which presents the following problems: 1. In terms of flue gas cooling, mixing cold air increases the flue gas volume by 4-5 times, significantly increasing the operating load of the fan, raising the initial investment and operating costs of the project. Furthermore, the dilution of the flue gas concentration reduces the treatment efficiency of borides and harmful gases. 2. Cooling via waste heat boilers or heat exchangers causes the borides to condense into a viscous liquid on the surface of the heat exchange tubes because the surface temperature is lower than the boiling point of the main borides. This viscous borides quickly coat the surface of the heat exchange tubes, causing a sharp decline in heat exchange efficiency in a short period. Simultaneously, the accumulation of borides on the surface of the heat exchange tubes obstructs flue gas flow, increasing the system's operating load. 3. In the SCR denitrification process, water vapor reacts with ammonia and NO... XPhysical adsorption competition occurs on the catalyst surface, so the presence of water vapor in the flue gas will cause a decrease in SCR denitrification efficiency. Therefore, the lower the water vapor content in the flue gas, the better. However, using water spray cooling will increase the water vapor content in the flue gas by tens of times, which will cause a sharp drop in SCR denitrification efficiency. At the same time, excessively high water vapor content will cause a noticeable "white cast" phenomenon at the chimney outlet.

[0005] Secondly, the removal of borides and acidic gases relies on the chemical activity of slaked lime for solidification and absorption. However, the reaction between borides and slaked lime is very slow, and the presence of carbon dioxide in the flue gas forms a hard shell on the surface of the slaked lime particles, quickly rendering the lime surface chemically inactive. Therefore, relying solely on chemical methods to remove borides from flue gas is inefficient, resulting in a high boride escape rate and accumulation of borides in downstream equipment. Furthermore, in existing SNCR denitrification processes, ammonia injection is located at the kiln exhaust port. Due to the excessively high temperature at the kiln exhaust port, some ammonia gas reacts with oxygen at high temperatures to generate nitric oxide, leading to increased NO levels in the flue gas. X An increase in the total amount.

[0006] In summary, existing waste gas treatment processes for boron-rich glass kilns still face many unavoidable problems. To date, the industry lacks mature, engineered solutions for treating boron-rich flue gas. Exploring engineered waste gas treatment processes for boron-rich glass kilns remains a focus of industry attention.

[0007] Therefore, this invention adjusts the sequence of steps in the existing SNCR denitrification process, and improves the specific implementation methods and devices of the ammonia injection process and dust removal process in the existing SNCR denitrification process, in order to improve the SCR denitrification efficiency. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of this invention is to provide a boron-rich glass furnace flue gas treatment device and process, which can achieve clean treatment of boron-rich glass furnace flue gas with high deboron and denitrification efficiency, low operating cost and simple and stable process performance.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A boron-rich glass kiln exhaust gas treatment device includes a first shell-and-tube heat exchanger, a conditioning tube, a honeycomb desuperheater, a bag filter, a second shell-and-tube heat exchanger, an SCR denitrification tower, and a chimney.

[0011] Both the first and second shell-and-tube heat exchangers can adopt common shell-and-tube structures in the prior art, and their structure is not the inventive point of this invention, so it will not be described in detail.

[0012] The tube outlet of the first shell-and-tube heat exchanger is connected to the inlet of the conditioning tube via a first connecting pipe.

[0013] The honeycomb desuperheater is equipped with an air inlet and an exhaust outlet;

[0014] The outlet end of the conditioning tube is connected to the air inlet of the honeycomb desuperheater through a second connecting tube;

[0015] The exhaust port of the honeycomb desuperheater is connected to the inlet of the bag filter through a third connecting pipe.

[0016] The outlet end of the bag filter is connected to the shell-side inlet end of the second shell-side heat exchanger through the fourth connecting pipe, and the shell-side outlet end of the second shell-side heat exchanger is connected to the inlet end of the SCR denitrification tower through the fifth connecting pipe.

[0017] The outlet of the SCR denitrification tower is connected to the inlet of the chimney via a sixth connecting pipe.

[0018] Specifically, the conditioning tube is set vertically, with the bottom end being the inlet and the top end being the outlet.

[0019] Specifically, the conditioning tube has the structure of a long strip tube with an aspect ratio of (2-5):1.

[0020] Specifically, there are three sets of turbulence generators inside the conditioning tube from bottom to top.

[0021] Preferably, the flow generator is an arc-shaped baffle. The function of the flow generator is to rapidly and uniformly mix the flue gas with the slaked lime, and to increase the contact probability and reaction path between the slaked lime and the boride and acidic gases. The function of the conditioning pipe is mainly to add fluidized slaked lime or quicklime powder to the flue gas and mix it thoroughly with the flue gas.

[0022] Specifically, the honeycomb desuperheater includes a heat exchange cylinder, an air inlet cover at the top of the heat exchange cylinder, and a waste ash bin at the bottom of the heat exchange cylinder; the air inlet cover and the heat exchange cylinder are separated by a first partition; the heat exchange cylinder and the waste ash bin are separated by a second partition.

[0023] The air inlet is located on the side wall of the air inlet cover, and the outlet end of the conditioning pipe is connected to the air inlet through a second connecting pipe.

[0024] Specifically, the heat exchange cylinder is equipped with several vertically arranged seamless steel pipes with specifications of DN40~DN60. The top opening of the seamless steel pipe passes through the first partition and enters the air inlet cover; the bottom opening of the seamless steel pipe passes through the second partition and enters the waste ash bin.

[0025] Preferably, 200 seamless steel pipes are used.

[0026] Preferably, the gaps between several seamless steel pipes inside the heat exchange cylinder are filled with water for heat exchange, and the side wall of the heat exchange cylinder is provided with an inlet pipe and an outlet pipe for water to enter and exit.

[0027] Furthermore, a pressure relief overflow pipe is also provided at the top of the heat exchange cylinder.

[0028] Preferably, the function of the honeycomb desuperheater is to control the flue gas temperature at the inlet of the bag filter to below 160℃. During operation, the honeycomb desuperheater exchanges heat with the flue gas inside the seamless steel pipe through the circulating flow of water, thereby removing heat from the flue gas. Due to the small diameter and sufficient number of seamless steel pipes, the flue gas moves at a low speed inside the seamless steel pipes, enabling a rapid drop in flue gas temperature within the honeycomb desuperheater.

[0029] Furthermore, the bottom opening of the seamless steel pipe is also equipped with a grid for filtering flue gas.

[0030] Furthermore, in order to prevent the gas flow inside the seamless steel pipe from being obstructed, a pulse blowing pipe is also provided at the air inlet end of each steel pipe. The blowing medium is compressed air, and the pulse blowing pipe can intermittently blow compressed air into the seamless steel pipe.

[0031] Furthermore, the exhaust port is located on the side wall of the waste ash bin; the bottom of the waste ash bin is provided with a first ash discharge port; the exhaust port of the waste ash bin is connected to the inlet end of the bag filter through a third connecting pipe.

[0032] Furthermore, the bottom of the bag filter is equipped with a second ash outlet.

[0033] Furthermore, the tube outlet of the second shell-and-tube heat exchanger is connected to the shell inlet of the first shell-and-tube heat exchanger, and the shell outlet of the first shell-and-tube heat exchanger is connected to the tube inlet of the second shell-and-tube heat exchanger. Through this connection, the flue gas in the tubes of the second shell-and-tube heat exchanger exchanges heat with the flue gas in the tubes of the first shell-and-tube heat exchanger.

[0034] Preferably, the function of the second shell-and-tube heat exchanger is to use the high temperature of the flue gas in the first shell-and-tube heat exchanger to reheat the cooled flue gas to 350-420°C after the flue gas is dusted, so as to meet the requirements of the SCR denitrification reaction in the SCR denitrification tower.

[0035] Preferably, the SCR denitrification tower functions to remove residual NOx from flue gas using catalytic reduction; the tower is equipped with a metal oxide catalyst, which includes components such as V2O5 and TiO2, specifically V2O5-WO3(MoO3) / TiO2; ammonia and NO are separated within the SCR denitrification tower. X A redox reaction occurs on the catalyst surface, NO X The ammonia gas is converted into harmless nitrogen and water and then discharged.

[0036] Furthermore, the sixth connecting pipe is also equipped with an induced draft fan, which is used to introduce the flue gas in the SCR denitrification tower into the chimney for discharge; the function of the induced draft fan is to generate negative pressure and provide power for the directional flow of flue gas.

[0037] Furthermore, the waste gas treatment device for the boron-rich glass kiln also includes an SNCR ammonia injection device, a feeder, and a cooling tower.

[0038] More preferably, the SNCR ammonia injection device includes an ammonia storage tank, an ammonia injection pipe, and an ammonia injection head disposed at the end of the ammonia injection pipe. The ammonia injection head extends into the side wall of the first connecting pipe, and the other end of the ammonia injection pipe is connected to the ammonia storage tank. The SNCR ammonia injection device can atomize ammonia and inject it into the first connecting pipe through the ammonia injection pipe and the ammonia injection head to exchange heat with the high-temperature flue gas discharged from the first shell-and-tube heat exchanger.

[0039] More preferably, the SNCR ammonia injection device mainly functions to inject ammonia water into the flue gas while simultaneously reducing the flue gas temperature to 900-1100℃. Under these conditions, the ammonia gas reacts with 30%-70% of the NO in the flue gas. X A reduction reaction occurs, removing NOx and producing nitrogen and water, thus reducing the processing pressure on the downstream SCR denitrification tower.

[0040] Furthermore, six ammonia spray heads are provided, which are symmetrically and evenly distributed on both sides of the axial centerline of the first connecting pipe.

[0041] Specifically, the outlet end of the feeder is connected to the side wall of the conditioning pipe, and the feeder introduces quicklime into the conditioning pipe to mix with the high-temperature flue gas inside the conditioning pipe.

[0042] Furthermore, the second ash discharge port of the bag filter is connected to the inlet end of the feeder through an ash discharge pipe.

[0043] Furthermore, the outlet of the cooling tower is connected to the inlet pipe of the heat exchange cylinder, and the inlet of the cooling tower is connected to the outlet pipe of the heat exchange cylinder, so that the water in the heat exchange cylinder can circulate through the cooling tower.

[0044] Furthermore, the present invention also provides a waste gas treatment process using the aforementioned device, the specific steps of which are as follows:

[0045] 1) Heat exchange and ammoniation: The high-temperature flue gas discharged from the boron-rich glass furnace enters the tube side of the first shell-and-tube heat exchanger through the pipe. When the high-temperature flue gas reaches the first connecting pipe through the first shell-and-tube heat exchanger, the ammonia spray head continuously sprays atomized ammonia water with a concentration of 8%-15%. The ammonia water vaporizes and absorbs heat to reduce the temperature of the high-temperature flue gas to 950℃-1100℃.

[0046] 2) Conditioning: The high-temperature flue gas after ammonia injection enters the conditioning pipe through the first connecting pipe; the feeder introduces quicklime into the conditioning pipe; the high-temperature flue gas flows upward from the bottom of the conditioning pipe; a turbulence generator is installed in the conditioning pipe to make the flue gas and quicklime mix quickly and evenly, increasing the contact probability and reaction path of quicklime with boride and acidic gases.

[0047] A vortex is generated inside the conditioning tube by a turbulence generator. Under the action of the vortex inside the conditioning tube, the quicklime is rapidly and fully mixed with the high-temperature flue gas to form a saturated atmosphere.

[0048] 3) Secondary heat exchange: High-temperature flue gas carrying a large amount of hydrated lime powder is discharged from the top outlet of the conditioning tube and enters the honeycomb desuperheater. The flue gas temperature entering the honeycomb desuperheater is 700-900℃. The high-temperature flue gas first enters the inlet cover, and then enters the heat exchange cylinder through the seamless steel pipe. In the heat exchange cylinder, it exchanges heat with water again, causing the temperature of the high-temperature flue gas to drop sharply in the honeycomb desuperheater.

[0049] During the cooling process, most of the borides in the flue gas condense from the gaseous state into droplets or solid particles and mix with slaked lime powder. When the flue gas carrying slaked lime powder reaches the outlet of the honeycomb desuperheater, the temperature has dropped to about 160°C.

[0050] As the flue gas travels through the honeycomb desuperheater, the particles in the flue gas fall into the ash bin from the grid at the bottom opening of the seamless steel pipe. Large dust particles are discharged from the first ash outlet at the bottom of the ash bin under the action of gravity and centripetal force, while small dust particles are discharged from the exhaust port on the side wall of the ash bin along with the flue gas, and then enter the bag filter through the third connecting pipe.

[0051] 4) Dust removal: A portion of the ash in the flue gas entering the bag filter is filtered out in the bag filter. The filtered ash is collected and discharged from the second ash outlet at the bottom of the bag filter. At the same time, a small amount of residual boride and HF in the flue gas are further removed by reacting with quicklime on the surface of the filter bag.

[0052] After dust removal, the low-temperature flue gas enters the shell side of the second shell-side heat exchanger through the fourth connecting pipe. At this time, the low-temperature flue gas exchanges heat with the high-temperature flue gas discharged from the shell side of the first shell-side heat exchanger, and the temperature rises to 350℃-420℃ to achieve reheating.

[0053] 5) Reduction reaction: The reheated flue gas enters the SCR denitrification tower through the fifth connecting pipe. Inside the SCR denitrification tower, ammonia and NO... X The catalyst undergoes a redox reaction on its surface, turning into nitrogen and water. Finally, the denitrified flue gas is sent to the chimney for exhaust.

[0054] Furthermore, in step 1), the high-temperature flue gas discharged from the boron-rich glass furnace has a temperature of about 1400℃ and contains harmful components such as boron oxide, hydrogen fluoride, and sulfides.

[0055] Specifically, in step 1), the ammonia spraying head has a flow rate of 200-220 L / h.

[0056] Furthermore, step 1) also includes the low-temperature flue gas flowing out from the tube side of the second shell-and-tube heat exchanger entering the shell side of the first shell-and-tube heat exchanger and exchanging heat with the high-temperature flue gas in the tube side of the first shell-and-tube heat exchanger.

[0057] Specifically, the ammonia gas after vaporization in step 1) and the slaked lime in step 2) are both used as boron removal agents.

[0058] Furthermore, in step 4), the ash discharged from the bottom of the bag filter enters the feeder through the ash discharge pipe for recycling.

[0059] Furthermore, in step 4), the dust removal process removes more than 99% of the particulate matter from the flue gas.

[0060] Furthermore, the process employs physical adhesion and chemical reaction to remove borides from the flue gas (removal rate above 95%), while simultaneously removing sulfides and fluorides from the flue gas (removal rate close to 100%). By employing a two-stage reaction—SNCR reaction in the first shell-and-tube heat exchanger and SCR in the SCR denitrification tower—nitrogen oxides in the flue gas can be removed.

[0061] Compared with the prior art, the present invention has the following advantages:

[0062] 1. This invention cools the flue gas by setting up an SNCR ammonia injection device and circulating water cooling. It does not require the introduction of cooling air, the total amount of flue gas is small, and the moisture content of the flue gas before denitrification can be controlled to the lowest level. The SCR denitrification efficiency is high and the operating cost of the fan is low.

[0063] 2. The process described in this invention uses a physical method to capture borides by forming a saturated atmosphere with fluidized lime and flue gas. Both large and small droplets can be adhered to and encapsulated by the densely distributed powder. After the flue gas enters the treatment system, borides will not adhere to or clog the flue, the inner walls of the equipment, or the surface of the filter bags in the bag filter. Therefore, frequent equipment cleaning due to boride adhesion and accumulation is unnecessary. The entire system has high boron removal efficiency and avoids the phenomenon of escaped borides adhering to and clogging the catalyst surface in the SCR denitrification tower, thus extending the service life of the denitrification catalyst.

[0064] 3. The process of this invention does not require the introduction of cold air or water spray cooling. The total amount of flue gas treated is equivalent to one-quarter of that of existing processes. This not only saves on the construction and operation costs of SCR denitrification towers, bag filters, and induced draft fans, but also improves the removal efficiency of harmful substances in flue gas and reduces the total amount of harmful substances escaping.

[0065] 4. This invention also enables the recycling of fluidized hydrated lime in the conditioning pipe, resulting in high utilization efficiency.

[0066] 5. The waste gas treatment process carried out by the device described in this invention can avoid the adhesion of borides in the flue and equipment, and almost completely remove borides, particles and harmful gases in the flue gas. Moreover, the process is simple, the equipment failure rate is low and the operating consumption is small. Attached Figure Description

[0067] Figure 1 is a schematic diagram of the structure of the device described in this invention. Detailed Implementation

[0068] To make the technical objectives, solutions, and beneficial effects of this invention clearer, the following description uses the flue gas treatment process of a 25T / D borosilicate glass kiln as an example to clearly and completely describe the technical solutions in the embodiments of this invention. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0069] Example 1

[0070] like Figure 1 As shown, a boron-rich glass kiln exhaust gas treatment device includes a first shell-and-tube heat exchanger 11, a conditioning tube 2, a honeycomb desuperheater 3, a bag filter 5, a second shell-and-tube heat exchanger 12, an SCR denitrification tower 6, and a chimney 7.

[0071] The first shell-and-tube heat exchanger 11 and the second shell-and-tube heat exchanger 12 can both adopt common shell-and-tube structures in the prior art, and their structure is not the point of invention of this invention, so it will not be described in detail.

[0072] Specifically, the conditioning tube 2 is set vertically, with the bottom end of the conditioning tube 2 being the inlet end and the top end being the outlet end;

[0073] The tube-side outlet end of the first shell-and-tube heat exchanger 11 is connected to the inlet end of the conditioning tube 2 via a first connecting pipe.

[0074] The conditioning pipe 2 is a long strip pipe with an aspect ratio of (2-5):1. Three sets of turbulence generators (specifically, in this embodiment, the turbulence generator is an arc-shaped baffle) are installed inside the conditioning pipe 2 from bottom to top to ensure rapid and uniform mixing of flue gas and quicklime, and to increase the contact probability and reaction path between the quicklime and borides and acidic gases. The main function of the conditioning pipe 2 is to add fluidized quicklime or lime powder to the flue gas and mix it thoroughly.

[0075] The honeycomb desuperheater 3 includes a heat exchange cylinder, an air inlet cover disposed at the top of the heat exchange cylinder, and a waste ash bin disposed at the bottom of the heat exchange cylinder; the air inlet cover and the heat exchange cylinder are separated by a first partition; the heat exchange cylinder and the waste ash bin are separated by a second partition.

[0076] The side wall of the air inlet cover is provided with an air inlet, and the outlet end of the conditioning pipe 2 is connected to the air inlet of the air inlet cover through a second connecting pipe.

[0077] The heat exchanger cylinder is equipped with several vertically arranged DN50 seamless steel pipes. The top opening of the seamless steel pipe passes through the first partition and into the air inlet cover; the bottom opening of the seamless steel pipe passes through the second partition and into the waste ash bin; the seamless steel pipe is 3.5 meters long, and the distance between the center lines of two connected steel pipes is 200 mm; preferably, 200 seamless steel pipes are provided in this embodiment.

[0078] The heat exchange cylinder is filled with water in the gaps between several seamless steel pipes for heat exchange, and the side wall of the heat exchange cylinder is provided with inlet pipe and outlet pipe for water to enter and exit.

[0079] The honeycomb desuperheater 3 is a water bath heat exchange structure, and its function is to control the flue gas temperature at the inlet of the bag filter 5 to below 160℃.

[0080] During operation, the honeycomb desuperheater 3 exchanges heat with the flue gas inside the seamless steel pipe through the circulating flow of water, thereby removing the heat from the flue gas. Due to the small diameter and sufficient number of seamless steel pipes, the flue gas moves at a low speed inside the seamless steel pipes, enabling the flue gas temperature to drop rapidly within the honeycomb desuperheater 3.

[0081] Furthermore, the bottom opening of the seamless steel pipe is also equipped with a grid for filtering flue gas.

[0082] Furthermore, in order to prevent the gas flow inside the seamless steel pipe from being obstructed, a pulse blowing pipe is also provided at the air inlet end of each steel pipe. The blowing medium is compressed air, and the pulse blowing pipe can intermittently blow compressed air into the seamless steel pipe.

[0083] The bottom of the waste ash bin is equipped with a first ash outlet, and the side wall of the waste ash bin is equipped with an exhaust outlet.

[0084] The exhaust port of the waste ash silo is connected to the inlet end of the bag filter 5 through the third connecting pipe.

[0085] The bag filter 5 has an outlet end on its side wall and a second ash discharge port at its bottom. The outlet end of the bag filter 5 is connected to the shell-side inlet end of the second shell-side heat exchanger 12 through a fourth connecting pipe, and the shell-side outlet end of the second shell-side heat exchanger 12 is connected to the inlet end of the SCR denitrification tower 6 through a fifth connecting pipe.

[0086] The tube-side outlet of the second shell-and-tube heat exchanger 12 is connected to the shell-side inlet of the first shell-and-tube heat exchanger 11, and the shell-side outlet of the first shell-and-tube heat exchanger 11 is connected to the tube-side inlet of the second shell-and-tube heat exchanger 12 (not shown in the figure). Through this connection, the flue gas in the tube side of the second shell-and-tube heat exchanger 12 exchanges heat with the flue gas in the tube side of the first shell-and-tube heat exchanger 11.

[0087] The function of the second shell-and-tube heat exchanger 12 is to use the high temperature of the flue gas in the first shell-and-tube heat exchanger 11 after the flue gas is de-dust treated to raise the temperature of the cooled flue gas back to 350-420℃, so as to meet the requirements of the SCR denitrification reaction in the SCR denitrification tower 6.

[0088] The outlet end of the SCR denitrification tower 6 is connected to the inlet end of the chimney 7 through the sixth connecting pipe.

[0089] The function of the SCR denitrification tower 6 is to remove residual NOx from the flue gas using catalytic reduction. The tower is equipped with a metal oxide catalyst, which includes components such as V2O5 and TiO2, specifically V2O5-WO3(MoO3) / TiO2. Ammonia and NO are present in the SCR denitrification tower 6. X A redox reaction occurs on the catalyst surface, NO X The ammonia gas is converted into harmless nitrogen and water and then discharged.

[0090] Furthermore, the sixth connecting pipe is also equipped with an induced draft fan 71, which is used to introduce the flue gas in the SCR denitrification tower 6 into the chimney 7 for discharge; the function of the induced draft fan 71 is to generate negative pressure and provide power for the directional flow of flue gas.

[0091] Furthermore, the waste gas treatment device for the boron-rich glass kiln also includes an SNCR ammonia injection device, a feeder 4, and a cooling tower (not shown in the figure).

[0092] The SNCR ammonia injection device includes an ammonia storage tank, an ammonia injection pipe 21, and an ammonia injection head disposed at the end of the ammonia injection pipe 21. The ammonia injection head extends into the side wall of the first connecting pipe, and the other end of the ammonia injection pipe 21 is connected to the ammonia storage tank. The SNCR ammonia injection device can atomize ammonia and inject it into the first connecting pipe through the ammonia injection pipe 21 and the ammonia injection head to exchange heat with the high-temperature flue gas discharged from the first shell-and-tube heat exchanger 11.

[0093] The main function of the SNCR ammonia injection device is to inject ammonia water into the flue gas and simultaneously reduce the flue gas temperature to 900-1100℃. Under these conditions, the ammonia gas reacts with 30%-70% of the NO in the flue gas. X A reduction reaction occurs, removing NOx and producing nitrogen and water, thus reducing the processing pressure on the downstream SCR denitrification tower.

[0094] Preferably, in this embodiment, six ammonia spray heads are provided, and the six ammonia spray heads are symmetrically and evenly distributed on both sides of the axial center line of the first connecting pipe.

[0095] The outlet end of the feeder 4 is connected to the side wall of the conditioning pipe 2. The feeder 4 feeds quicklime into the conditioning pipe 2 and mixes it with the high-temperature flue gas in the conditioning pipe 2.

[0096] Furthermore, the second ash discharge port of the bag filter 5 is connected to the inlet end of the feeder 4 through the ash discharge pipe (not shown in the figure).

[0097] The outlet of the cooling tower is connected to the inlet pipe of the heat exchange cylinder, and the inlet of the cooling tower is connected to the outlet pipe of the heat exchange cylinder, so that the water in the heat exchange cylinder can circulate through the cooling tower.

[0098] Furthermore, a pressure relief overflow pipe is also provided at the top of the heat exchange cylinder.

[0099] Example 2

[0100] Example 2 provides a waste gas treatment process using the apparatus described in Example 1, specifically including the following steps:

[0101] 1) Heat exchange and ammoniation: High-temperature flue gas (around 1400℃, containing NO) discharged from the boron-rich glass furnace. X Harmful components such as boron oxide, hydrogen fluoride, and sulfides enter the tube side of the first shell-and-tube heat exchanger 11 through the pipe. The low-temperature flue gas flowing out from the tube side of the second shell-and-tube heat exchanger 12 enters the shell side of the first shell-and-tube heat exchanger 11 and exchanges heat with the high-temperature flue gas in the tube side of the first shell-and-tube heat exchanger 11. When the high-temperature flue gas reaches the first connecting pipe after heat exchange, the ammonia spray head continuously sprays atomized ammonia water with a concentration of 12% at a flow rate of 210L / h. The ammonia water vaporizes and absorbs heat, reducing the temperature of the high-temperature flue gas to 950℃-1100℃.

[0102] The concentration and injection rate of ammonia are determined by a combination of the temperature of the high-temperature flue gas after treatment by the SNCR ammonia injection unit and the ammonia concentration at the outlet of SCR denitrification tower 6. During ammoniation, some borides in the high-temperature flue gas react chemically with ammonia to form boron nitride, while ammonia also reacts with some NO in the high-temperature flue gas. X It undergoes a reduction reaction and is converted into nitrogen gas and water;

[0103] 2) Conditioning: The high-temperature flue gas after ammonia injection enters the conditioning pipe 2 through the first connecting pipe; the feeder 4 feeds quicklime into the conditioning pipe 2; the high-temperature flue gas flows upward from the bottom end of the conditioning pipe 2; the structure of the conditioning pipe 2 is a long strip pipe with a length-to-width ratio of (2-5):1, and the conditioning pipe 2 is equipped with 3 sets of turbulence generators to make the flue gas and quicklime mix quickly and evenly, and increase the contact probability and reaction path of quicklime with borate and acidic gas;

[0104] A vortex is formed in the conditioning tube 2 by a turbulence generator. Under the action of the vortex in the conditioning tube 2, the slaked lime is rapidly and fully mixed with the high-temperature flue gas to form a saturated atmosphere.

[0105] In this process, the ammonia gas vaporized in step 1) and the slaked lime in step 2) are both used as boron removal agents.

[0106] 3) Secondary heat exchange: High-temperature flue gas carrying a large amount of hydrated lime powder is discharged from the top outlet of conditioning pipe 2 and enters honeycomb desuperheater 3. The flue gas temperature entering honeycomb desuperheater 3 is 800℃. The high-temperature flue gas first enters the air inlet cover, and then enters the heat exchange cylinder through DN50 seamless steel pipe. In the heat exchange cylinder, it exchanges heat with water again, causing the temperature of the high-temperature flue gas to drop sharply in honeycomb desuperheater 3.

[0107] During the cooling process, most of the borides in the flue gas condense from the gaseous state into droplets or solid particles and mix with the slaked lime powder. When the flue gas carrying the slaked lime powder reaches the outlet of the honeycomb desuperheater 3, the temperature has dropped to about 160°C.

[0108] To prevent the hydrated lime powder adhering to the inner wall of the seamless steel pipe from becoming too thick and causing a decrease in heat exchange efficiency, a pulse blowing pipe is also provided at the air inlet end of each steel pipe. The blowing medium is compressed air, and the pulse blowing pipe can intermittently blow compressed air into the seamless steel pipe.

[0109] As the flue gas travels within the honeycomb desuperheater 3, particles in the flue gas fall into the ash bin from the grid at the bottom opening of the seamless steel pipe. Large dust particles are discharged from the first ash outlet at the bottom of the ash bin under the action of gravity and centripetal force, while small dust particles are discharged from the exhaust port on the side wall of the ash bin along with the flue gas, and then enter the bag filter 5 through the third connecting pipe.

[0110] 4) Dust removal: A portion of the ash in the flue gas entering the bag filter 5 is filtered out in the bag filter 5. The filtered ash is collected and discharged from the second ash outlet at the bottom of the bag filter 5, and then enters the feeder 4 through the ash discharge pipe for recycling. At the same time, a small amount of residual boride and HF in the flue gas react with quicklime on the surface of the filter bag and are further removed.

[0111] The low-temperature flue gas after dust removal (the dust removal process removes more than 99% of the particulate matter in the flue gas) enters the shell side of the second shell-side heat exchanger 12 through the fourth connecting pipe. At this time, the low-temperature flue gas exchanges heat with the high-temperature flue gas discharged from the shell side of the first shell-side heat exchanger 11, and the temperature rises to 350℃-420℃ to achieve reheating.

[0112] 5) Reduction reaction: The reheated flue gas enters the SCR denitrification tower 6 through the fifth connecting pipe. Inside the SCR denitrification tower 6, ammonia and NO... X A redox reaction occurs on the catalyst surface, producing nitrogen and water. The catalyst is specifically V₂O₅-WO₃(MoO₃) / TiO₂. At this point, the ammonia and NO in the flue gas... X Concentrations were all controlled below environmental protection requirements (specifically, NOx concentration was below 50 mg / m³). 3 Below, the ammonia slip rate is 2.5 mg / m³. 3 (The following), the denitrified flue gas is finally sent to the chimney 7 for exhaust by the induced draft fan 71.

[0113] Specifically, in step 1) of the process, the total volume of the high-temperature flue gas discharged from the boron-rich glass furnace is 900 m³. 3 / h, nitrogen oxide concentration 3700 mg / m 3 Borides 800 mg / m 3 HF is 100 mg / m³ 3 Particulate matter 4600 mg / m³ 3 .

[0114] The process described in this invention can ultimately achieve a boride removal rate of over 95%, a sulfide and fluoride removal rate of nearly 100% for acidic gases, and a nitrogen oxide removal rate of over 98.5%.

[0115] The process described in this invention removes borides from flue gas mainly through two pathways: firstly, ammonia and boron oxide vapors react chemically in the first shell-and-tube heat exchanger 11 to generate solid boron nitride; secondly, saturated fluidized bed particles in the flue gas can physically adhere to boride droplets in the flue gas.

[0116] During operation, the process described in this embodiment can be monitored by detecting whether the flue gas temperature after ammonia injection reaches 950-1100℃, and the NO content in the flue gas at the outlet of SCR denitrification tower 6. XThe content of NH3 is adjusted to control the concentration of ammonia water and the amount of ammonia sprayed in order to achieve the best ammoniation effect.

[0117] In the process described in this embodiment, fluidized slaked lime is added to the flue gas in the conditioning pipe 2 through the feeder 4; wherein, the source of the slaked lime in the feeder 4 is the circulating slaked lime collected by the bag filter 5 and the newly added fresh slaked lime.

[0118] In the process described in this embodiment, the separation of large and small particles in the flue gas is achieved through the grid set at the bottom opening of the seamless steel pipe. During the rectification process cycle, the dust collected by the bag filter 5 is recycled until the particles become larger and are separated from the circulation system by the grid at the bottom opening of the seamless steel pipe.

[0119] In the process described in this embodiment, the feeder 4 introduces approximately 200 kg / h of hydrated lime into the conditioning pipe 2. The purpose of introducing a large amount of fluidized hydrated lime powder into the conditioning pipe 2 through the feeder 4 is primarily to ensure sufficient lime powder adheres to the subsequent pipe walls and the inner surfaces of various equipment, especially on the inner surface of the honeycomb desuperheater 3, thereby preventing borides from adhering to the inner wall of the pipe. Simultaneously, the fluidized lime powder is also used to remove acidic gases such as HF from the flue gas.

[0120] In this invention, the ammonia treatment process of high-temperature flue gas in the first shell-and-tube heat exchanger 11 mainly employs a selective non-catalytic reduction (SNCR) process. This method involves atomizing a nitrogen-containing reducing agent (urea, ammonia water, or liquid ammonia) and injecting it into the flue gas at a temperature of 850-1100℃, causing a reduction reaction that removes NOx and produces nitrogen and water. Because the reduction of NOx by the nitrogen-containing reducing agent is selective within a certain temperature range and in the presence of oxygen, it is superior to other reactions, and since no catalyst is required in the reaction, it is called selective non-catalytic reduction.

[0121] By employing an ammonia injection head that extends into the side wall of the first connecting pipe, and having several ammonia injection heads symmetrically and evenly distributed on both sides of the axial centerline of the first connecting pipe, this invention makes it easier to control the reaction temperature of the SNCR process within the range of 850℃-1100℃, greatly reducing the possibility that some ammonia gas will react with oxygen to generate nitric oxide under high temperature conditions.

[0122] Throughout the entire process of this invention, the amount of ambient temperature air supplied to the flue gas is zero, which can greatly reduce the workload of the terminal fans.

[0123] The process described in this invention can control the moisture content in the flue gas before denitrification to a minimum (specifically 4.0%) through the SNCR ammonia injection device, thereby minimizing the competition between water vapor and ammonia gas during physical adsorption on the surface of the denitrification catalyst and improving the denitrification efficiency of the denitrification catalyst.

[0124] Overall, the process described in this invention, due to the small total amount of flue gas, not only reduces the construction and operating costs of denitrification, dust removal, and ventilation systems, but also reduces the amount of deboronizing and denitrifying agents used (in step 1), the gasified ammonia and the slaked lime in step 2 are both used as deboronizing agents; the amount of slaked lime added is 150 kg / h to 250 kg / h, preferably 200 kg / h; the amount of ammonia injected ensures that the mass ratio of ammonia to nitrogen oxides in the flue gas is 4-6:1, improving the system's efficiency in treating harmful substances in the flue gas. Most importantly, before deboronization of the flue gas, the boron-rich glass kiln exhaust gas treatment device of this invention has a sufficient amount of fluidized ash particles adhering to the entire inner wall of the flue gas passage, completely avoiding the problem of boride adhesion inside the flue, conditioning pipe, desuperheater, and dust removal facilities.

[0125] This invention mainly uses physical adhesion and chemical reaction to remove borides from flue gas (removal rate of over 95%), while also removing sulfides and fluorides from flue gas (removal rate close to 100%). By employing a two-stage reaction of SNCR reaction in the first shell-and-tube heat exchanger 11 and SCR in the SCR denitrification tower 6, nitrogen oxides in flue gas can be removed.

[0126] The honeycomb desuperheater 3 of this invention uses a water bath to reduce the flue gas temperature below the melting point of borides, and a bag filter 5 removes particulate matter from the flue gas, ultimately achieving clean emission of the flue gas. This invention has good treatment effect on boron-containing waste gas, is highly targeted, and has good potential for widespread application.

[0127] In summary, the device described in this invention has a simple structure, high reliability, and long service life; the process has low operating costs and can fully achieve the goal of efficiently treating the flue gas from boron-rich glass furnaces to meet clean emission standards (the emission standards are the "Emission Standards for Air Pollutants in the Glass Industry," which mainly limit the emission concentrations of nitrogen oxides, particulate matter, sulfides, etc.).

[0128] In the description of this invention, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0129] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0130] Finally, it should be noted that the above are merely preferred embodiments and application principles of the present invention. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the specific embodiments described herein, and may include many other effective embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A waste gas treatment process utilizing a boron-rich glass furnace waste gas treatment device, characterized in that, The waste gas treatment device for the boron-rich glass kiln includes a first shell-and-tube heat exchanger, a conditioning tube, a honeycomb desuperheater, a bag filter, a second shell-and-tube heat exchanger, an SCR denitrification tower, and a chimney. The tube outlet of the first shell-and-tube heat exchanger is connected to the inlet of the conditioning tube via a first connecting pipe. The honeycomb desuperheater is equipped with an air inlet and an exhaust outlet; The outlet end of the conditioning tube is connected to the air inlet of the honeycomb desuperheater through a second connecting tube; The exhaust port of the honeycomb desuperheater is connected to the inlet of the bag filter through a third connecting pipe. The outlet end of the bag filter is connected to the shell-side inlet end of the second shell-side heat exchanger through the fourth connecting pipe, and the shell-side outlet end of the second shell-side heat exchanger is connected to the inlet end of the SCR denitrification tower through the fifth connecting pipe. The outlet end of the SCR denitrification tower is connected to the inlet end of the chimney through the sixth connecting pipe; The honeycomb desuperheater includes a heat exchange cylinder, an air inlet cover at the top of the heat exchange cylinder, and a waste ash bin at the bottom of the heat exchange cylinder; the air inlet cover and the heat exchange cylinder are separated by a first partition; the heat exchange cylinder and the waste ash bin are separated by a second partition. The air inlet is located on the side wall of the air inlet cover, and the outlet end of the conditioning pipe is connected to the air inlet through a second connecting pipe. The heat exchange cylinder is equipped with several vertically arranged seamless steel pipes. The top opening of the seamless steel pipe passes through the first partition and into the air inlet cover; the bottom opening of the seamless steel pipe passes through the second partition and into the waste ash bin. The waste gas treatment device for the boron-rich glass kiln also includes an SNCR ammonia injection device, a feeder, and a cooling tower. The SNCR ammonia injection device includes an ammonia storage tank, an ammonia injection pipe, and an ammonia injection head disposed at the end of the ammonia injection pipe. The ammonia injection head extends into the side wall of the first connecting pipe, and the other end of the ammonia injection pipe is connected to the ammonia storage tank. The outlet end of the feeder is connected to the side wall of the conditioning tube; The conditioning tube is set vertically, with the bottom end of the conditioning tube being the inlet end and the top end being the outlet end; The conditioning tube is a long strip tube with an aspect ratio of (2-5):1; Three sets of turbulence generators are installed inside the conditioning tube from bottom to top; The turbulence generator is an arc-shaped baffle. Each steel pipe is also equipped with a pulse blowing pipe at the air inlet end, and the blowing medium is compressed air; The tube-side outlet of the second shell-and-tube heat exchanger is connected to the shell-side inlet of the first shell-and-tube heat exchanger, and the shell-side outlet of the first shell-and-tube heat exchanger is connected to the tube-side inlet of the second shell-and-tube heat exchanger. The outlet of the cooling tower is connected to the inlet pipe of the heat exchange cylinder, and the inlet of the cooling tower is connected to the outlet pipe of the heat exchange cylinder, so that the water in the heat exchange cylinder can circulate through the cooling tower. The seamless steel pipe is 3.5 meters long, and the distance between the center lines of two connected steel pipes is 200 mm. The SCR denitrification tower is filled with a metal oxide catalyst, which is V2O5-WO3(MoO3) / TiO2; The waste gas treatment process using a boron-rich glass furnace waste gas treatment device includes the following steps: 1) Heat exchange and ammoniation: The high-temperature flue gas discharged from the boron-rich glass furnace enters the tube side of the first shell-and-tube heat exchanger through the pipe. When the high-temperature flue gas reaches the first connecting pipe through the first shell-and-tube heat exchanger, the ammonia spray head continuously sprays atomized ammonia water with a concentration of 8%-15%. The ammonia water vaporizes and absorbs heat to reduce the temperature of the high-temperature flue gas to 950℃-1100℃. 2) Conditioning: The high-temperature flue gas after ammonia injection enters the conditioning pipe through the first connecting pipe; the feeder introduces quicklime into the conditioning pipe; a turbulence generator is installed inside the conditioning pipe; A vortex is generated inside the conditioning tube by a turbulence generator. Under the action of the vortex inside the conditioning tube, the slaked lime and high-temperature flue gas are fully mixed to form a saturated atmosphere. 3) Secondary heat exchange: High-temperature flue gas carrying a large amount of hydrated lime powder is discharged from the top outlet of the conditioning tube and enters the honeycomb desuperheater. The flue gas temperature entering the honeycomb desuperheater is 700-900℃. The high-temperature flue gas first enters the inlet cover, and then enters the heat exchange cylinder through the seamless steel pipe. In the heat exchange cylinder, it exchanges heat with water again, causing the temperature of the high-temperature flue gas to drop sharply in the honeycomb desuperheater. As the flue gas travels through the honeycomb desuperheater, the particles in the flue gas fall into the ash bin. Large dust particles are discharged from the first ash outlet at the bottom of the ash bin under the action of gravity and centripetal force, while small dust particles are discharged from the exhaust outlet on the side wall of the ash bin along with the flue gas, and then enter the bag filter through the third connecting pipe. 4) Dust removal: A portion of the ash in the flue gas entering the bag filter is filtered out in the bag filter. The filtered ash is collected and discharged from the second ash outlet at the bottom of the bag filter. After dust removal, the low-temperature flue gas enters the shell side of the second shell-side heat exchanger through the fourth connecting pipe. At this time, the low-temperature flue gas exchanges heat with the high-temperature flue gas discharged from the shell side of the first shell-side heat exchanger, and the temperature rises to 350℃-420℃ to achieve reheating. 5) Reduction reaction: The reheated flue gas enters the SCR denitrification tower through the fifth connecting pipe. Inside the SCR denitrification tower, ammonia and NO... X The catalyst surface undergoes an oxidation-reduction reaction to become nitrogen and water, and the denitrified flue gas is finally sent to the chimney for exhaust. In step 1), the high-temperature flue gas discharged from the boron-rich glass furnace has a temperature of 1400℃ and contains boron oxide, hydrogen fluoride, and sulfides. In step 1), the ammonia spray head has a flow rate of 200-220 L / h.

2. The waste gas treatment process according to claim 1, characterized in that, The exhaust port is located on the side wall of the waste ash bin; the bottom of the waste ash bin is provided with a first ash discharge port; the exhaust port of the waste ash bin is connected to the inlet end of the bag filter through a third connecting pipe.

3. The waste gas treatment process according to claim 1, characterized in that, A blower is also installed on the sixth connecting pipe.

4. The waste gas treatment process according to claim 1, characterized in that, The second ash discharge port of the bag filter is connected to the inlet of the feeder through the ash discharge pipe.

5. The waste gas treatment process according to claim 1, characterized in that, Step 1) also includes the low-temperature flue gas flowing out from the tube side of the second shell-and-tube heat exchanger entering the shell side of the first shell-and-tube heat exchanger and exchanging heat with the high-temperature flue gas in the tube side of the first shell-and-tube heat exchanger. The ammonia gas vaporized in step 1) and the slaked lime in step 2) are both used as boron removal agents; In step 4), the dust removal process removes more than 99% of the particulate matter from the flue gas; The process uses physical adhesion and chemical reaction to remove borides from flue gas, while also removing sulfides and fluorides. By employing a two-stage reaction, SNCR in the first shell-and-tube heat exchanger and SCR in the SCR denitrification tower, nitrogen oxides in the flue gas can be removed.

6. The waste gas treatment process according to claim 1, characterized in that, In step 1) of the process, the high-temperature flue gas discharged from the boron-rich glass furnace has a total flue gas volume of 900 m³. 3 / h, nitrogen oxide concentration 3700 mg / m 3 Borides 800 mg / m 3 HF is 100 mg / m³ 3 Particulate matter 4600 mg / m³ 3 .

7. The waste gas treatment process according to claim 1, characterized in that, Quicklime is used as a boron remover; the amount of quicklime added is between 150 kg / h and 250 kg / h.

8. The waste gas treatment process according to claim 1, characterized in that, The amount of ammonia injected is such that the mass ratio of ammonia to nitrogen oxides in the flue gas is (4-6):1.

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