System for evaluating performance of flue gas denitration catalyst
By designing a catalyst performance test system, the existing SCR denitrification catalysts have been solved, and the problem of poor denitrification performance and easy contamination at low temperatures is achieved, real-time evaluation and monitoring of catalyst performance is achieved, the service life of the catalyst is extended and NOX emissions are ensured.
Patent Information
- Application Number
- CN202411949714.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-06-24
AI Technical Summary
The existing SCR denitrification catalysts have poor denitrification performance at low temperatures and are easily contaminated by pollutants in the flue gas, resulting in low denitrification efficiency and short catalyst life.
A catalyst performance testing system was designed, including a simulated flue gas cylinder group, filter, mass flowmeter, gas mixing tank, preheating device, reaction tube furnace and flue gas analyzer. By simulating the mixing of flue gas and reducing agent NH3, the catalyst denitrification efficiency at different temperatures is monitored in real time.
Real-time evaluation and monitoring of the catalyst denitrification performance is achieved, and the catalyst performance can be tested under different working conditions, extend the catalyst service life and ensure NOX emissions meet standards.
Smart Images
Figure CN120195346A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of air pollutant control, and particularly relates to a system for evaluating the performance of flue gas denitration catalysts. Background Art
[0002] According to the data statistics of the "Annual Report on Environmental Statistics" in recent years, China has achieved remarkable results in the control of sulfur dioxide and dust. The total emissions of pollutants such as sulfur dioxide and dust are both decreasing. Although the total emissions of nitrogen oxides generally show a downward trend, the total amount is still very large. The elimination of NO X still needs to be further strengthened. In the flue gas denitration technology, the dry flue gas denitration technology has the advantages of low investment, simple equipment process, good effect of removing nitrogen oxides, and more environmental protection. At the same time, the reduction method is more common in dry denitration, which includes SNCR (selective non-catalytic reduction) and SCR (selective catalytic reduction). However, the temperature of the SNCR process is very high and difficult to control, and its denitration rate is very low. SCR is currently the most widely used and most effective flue gas denitration technology in the world (with a denitration rate of 80%-90%). Its principle is to use NH3 and urea as reducing agents, and under the action of a catalyst, convert NO X into pollution-free N2 and H2O.
[0003] The catalyst is the core of the SCR process. At present, the traditional commercial V2O5-WO3 / TiO2 catalyst has poor denitration performance at low temperatures, and will bring by-product N2O, and itself also has certain toxicity, causing certain difficulties for the recycling of the catalyst. At the same time, the catalyst is in high-dust flue gas, and As, H2O, SO2, heavy metals, and alkaline earth metals in the flue gas will contaminate or poison the catalyst. There are also situations where fly ash wears the reactor and blocks the catalyst. Therefore, it is necessary to develop a new type of SCR denitration catalyst with good denitration performance, strong resistance to H2O / SO2, resistance to alkaline earth metals, heavy metals, green, and low cost.
[0004] Carrying out denitration performance tests on different catalysts and studying the changes in the denitration performance of catalysts under different operating conditions are of great significance for developing new SCR catalysts, increasing the service life of catalysts, and ensuring the X up-to-standard emission of NO. Summary of the Invention
[0005] The purpose of the present invention is to form an operating system with simple operation, capable of flexibly operating to replace the components of the gas to be tested, and capable of understanding and evaluating the denitration performance of the selected catalyst in real time.
[0006] The technical solution of the present invention is a complete catalyst performance test system composed of a simulated flue gas gas cylinder group, a filter, a multi-range multi-gas mass flowmeter, a gas mixing tank, a preheating device, a reaction tube furnace, a flue gas analyzer, etc. Before the test starts, the set flow rates of different gas components are input into the computer that controls the mass flowmeter. The catalyst sample to be tested is placed in the reaction tube furnace. After introducing N2 for preheating for a period of time, simulated flue gas and reducing agent NH3 are introduced. By programming the temperature increase of the tube furnace and using the flue gas analyzer to detect the concentration of nitrogen oxides before and after the reaction, the denitrification efficiency of the catalyst at different temperatures can be obtained. The calculation formula for the denitrification efficiency of the catalyst is as follows:
[0007] γNO = (C1 - C2) / C1
[0008] In the formula, C1 is the NO X concentration at the inlet of the reaction tube furnace, and C2 is the NO X concentration at the outlet
[0009] The device structure description of the present invention is as shown in the attached Figure 1 specification. The gas cylinder group (1 - 6) includes gases (NO, SO2, NO2) simulating flue gas components, protective gas (N2), reaction gas (O2), and reducing agent (NH3). The outlet pressure of the gas cylinder is regulated by a pressure reducing valve (7), and a one-way valve (8) prevents gas backflow. The filter (9) is used to filter the gas to prevent the mass flowmeter from being blocked. The digital multi-range multi-gas mass flowmeter (11) controlled by a computer (10) pre-sets accurate gas flow rates, and the mass flowmeter can monitor the flue gas temperature in real time. A stop valve (12) is set to open or cut off a certain circuit according to requirements. The simulated flue gas is mixed and preheated in the gas mixing tank (13). To reduce experimental errors, a rotameter (14) is set after preheating the gas mixing tank (13) to further determine the gas flow rate. The simulated gas components pass through a three-way joint (15). One circuit enters the gas collection bag (21) to test the nitrogen oxide concentration before the reaction, and the other circuit enters the reaction vertical tube furnace (16). Different diameters of detachable quartz tubes are provided inside the tube furnace (16). Different shapes and sizes of monolithic catalysts or powdery catalysts with different particle sizes (17) can be placed inside the quartz tubes and fixed with fireproof cotton (18) before and after. The reaction tube furnace is equipped with an intelligent precise temperature control system for program temperature control. There are two independent temperature control systems in two temperature zones respectively. The flue gas concentration at the inlet and outlet of the reaction tube furnace is monitored in real time by the flue gas analyzer (19). After the experiment, the tail gas is treated by the tail gas treatment device (20) and then discharged into the atmosphere.
[0010] Operation process of the present invention: Select quartz tubes with different inner diameters according to the size of the catalyst sample to be tested. Before and after loading the catalyst into the quartz tube, use a burning cotton to block the catalyst at both ends to ensure smooth gas flow. Then install the quartz tube in the tube furnace reactor to ensure tightness. Use a digitally controlled mass flowmeter to preset the gas flow rate in advance and set the heating program of the tube furnace, and then introduce simulated flue gas (N2, O2, NO, NH3, NO2). The simulated flue gas is mixed evenly in the preheating gas mixing tank and the gas is preheated at the same time. Ensure that the loop for the gas to enter the tube furnace is closed. After the gas flow rate is stable, use a flue gas analyzer to measure the concentration of nitrogen oxides before treatment. Then close the loop for the gas discharged before treatment and open the loop for the gas to enter the tube furnace. Run the tube furnace to increase the temperature programatically. After heating to the next set temperature, measure the concentration of nitrogen oxides at the outlet. Repeat the above operations after the tube furnace heats up to the next temperature to measure the denitrification efficiency of the catalyst at different temperatures.
[0011] Features of the present invention:
[0012] (1) A filter is adopted and placed between the gas cylinder group and the mass flowmeter to prevent the mass flowmeter from being blocked.
[0013] (2) A multi-range and multi-gas digital mass flowmeter is adopted to precisely control the gas flow rate and the flue gas ratio on the computer. At the same time, without adding an additional mass flowmeter, a simulated flue gas component (NO2) can be flexibly operated to facilitate exploring the sensitivity of the catalyst to NO2 / NO X and the rapid SCR performance, etc. For example, a mass flowmeter of model CS200A can be applicable to multiple gases (such as NO, SO2, NO2, etc.). When exploring the sensitivity of the catalyst to NO2 / NO X , the simulated flue gas components need to be increased from NO to two components of NO and NO2. The address number of the SO2 mass flowmeter can be changed to the address number of NO2 on the computer side to realize the multi-purpose of the gas distribution system.
[0014] A vertical tube furnace reactor is adopted, and both ends are controlled by two independent temperature control systems to increase the length of the constant temperature section.
[0015] The tube furnace is set with an intelligent 30-segment programmable control for heating and cooling, monitoring the furnace temperature and the flue gas temperature at any time, and the temperature control accuracy is within ±1°C.
[0016] A detachable quartz tube is arranged inside the reaction tube furnace. According to the inner diameter of the quartz tube, monolithic catalysts with different shapes and sizes or powder catalysts with different particle sizes can be placed.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows.
[0018] Overall, the operating system is simple to run, with precise parameter adjustment, enabling flexible operation and facilitating the testing of catalyst performance under different working conditions. Description of the Drawings
[0019] Attached to the specification Figure 1 Schematic diagram of the system device for testing the performance of flue gas denitration catalyst Detailed implementation manners
[0020] Example 1:
[0021] Take 3 ml of powdered denitration catalyst and place it in a vertical tube furnace, blocked by fire cotton at both ends. Set the programmed temperature rise of the tube furnace to ensure that the reaction temperature of the simulated flue gas is between 100°C and 320°C, and the space velocity GHSV = 12000 h -1 , and the ammonia-nitrogen ratio is 1.08. In the simulated flue gas composition, N2 is 560 - 570 ml / min, NO is 0.24 ml / min, O2 is 30 ml / min, and NH3 is 0.26 ml / min. It is measured that the highest denitration efficiency of the catalyst is 85.7% at 260°C
[0022] Example 2:
[0023] Take 4 ml of granular denitration catalyst and place it in a vertical tube furnace, blocked by fire cotton at both ends. Set the programmed temperature rise of the tube furnace to ensure that the reaction temperature of the simulated flue gas is between 100°C and 320°C, and the space velocity SV = 9000 h -1 , and the ammonia-nitrogen ratio is 1.11. In the simulated flue gas composition, N2 is 560 - 570 ml / min, NO is 0.24 ml / min, O2 is 42 ml / min, and NH3 is 0.26 ml / min. It is measured that the highest denitration efficiency of the catalyst is 73.3% at 280°C
[0024] Example 3:
[0025] Take 4 ml of block-shaped denitration catalyst and place it in a vertical tube furnace, blocked by fire cotton at both ends. Set the programmed temperature rise of the tube furnace to ensure that the reaction temperature of the simulated flue gas is between 100°C and 320°C, and the space velocity SV = 9000 h -1 , and the ammonia-nitrogen ratio is 1.16. In the simulated flue gas composition, N2 is 560 - 570 ml / min, NO is 0.24 ml / min, O2 is 30 ml / min, and NH3 is 0.28 ml / min. It is measured that the highest denitration efficiency of the catalyst is 76.1% at 300°C.
Claims
1. A system for evaluating the performance of flue gas denitrification catalysts, comprising the following equipment: a gas cylinder group, wherein the simulated gas components include the main components in the simulated flue gas such as N2 (1), O2 (2), NO (4), NO2 (5), SO2 (6) and other gases and the reducing agent NH3 (3), and the outlet pressure of the gas cylinder is adjusted by a pressure reducing valve (7), a one-way valve (8) prevents gas backflow, and a filter (9) filters the gas to prevent clogging of the mass flow meter. According to the content of the catalyst performance, the gas address of the corresponding gas cylinder group is selected on the computer side (10), and the gas flow rate is accurately adjusted through the multi-range multi-gas mass flow meter (11) to achieve the gas ratio required for the experiment. A stop valve (12) is set to open or close a certain circuit according to demand. Subsequently, all simulated gas components enter the preheating mixing tank (13) to be evenly mixed and reach the preheating temperature. In order to reduce the experimental error, a rotor flowmeter (14) is set after the preheating mixing tank (13) to further determine the gas flow rate. Then, the simulated gas components pass through the three-way (15), one loop enters the gas collecting bag (21) to test the nitrogen oxide concentration before the reaction, and the other loop enters the reaction vertical tube furnace (16). The furnace cavity is square, and there are two independent temperature control devices at the top and bottom to increase the length of the constant temperature section. The control panel at the bottom is used for program temperature control and can monitor the temperature in the furnace in real time. A detachable quartz tube is set in the tube furnace (16) to place the catalyst sample (17), and quartz wool (18) is fixed at the front and back to ensure smooth gas circulation. The concentration of the simulated flue gas components before and after entering the reaction tube furnace is tested by the flue gas analyzer (19). Finally, the simulated gas components are treated by the purifier (20) and discharged into the air.
2. The system for testing the performance of flue gas denitration catalyst according to claim 1, characterized in that: A filter is used to prevent the mass flow meter from being blocked. A digital multi-range multi-gas mass flow meter is used to accurately control the gas flow and can be flexibly operated to achieve multi-purpose use. Quartz tubes with different inner diameters can be used to place catalyst samples of different sizes, shapes and volumes. A reaction vertical tubular furnace with two independent temperature control systems is used to increase the length of the constant temperature section. The tubular furnace program temperature control is used to more accurately control and detect the temperature.
3. The system for testing the denitration performance of a catalyst according to claim 1, characterized in that: The simulated flue gas volume space velocity (GHSV) can be adjusted by changing the catalyst volume. Since there are two independent temperature control systems at both ends of the tubular furnace, the constant temperature section length is increased, so the volume of catalyst that can be added is also greatly increased, and thus the adjustable range of the volume space velocity is large.
4. The system for testing the denitration performance of a catalyst according to claim 1, characterized in that: The simulated flue gas described above uses high-purity gas with a purity of 99.99%. The flue gas concentration can be adjusted according to demand, and the adjustable concentration range is large.
5. The system for testing the denitration performance of a catalyst according to claim 1, characterized in that: The simulated flue gas reaction catalytic temperature is 100°C-320°C.
6. The device for testing the denitration performance of a catalyst according to claim 1, characterized in that: The ratio of ammonia nitrogen in the simulated gas components is NO: NH3 (reducing agent) is 0.8-1.2.