The content of effective gaseous components is low, with a low level of carbon monoxide
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The gasification furnace in our project is a four-nozzle water-coal slurry counterflow gasification furnace with a diameter of 4000 mm, jointly designed by Yankuang and East China University of Science and Technology. The load on this furnace has been increased to 137 cubic meters of coal slurry. During operation, it was found that the content of useful gases in the process gas is relatively low, around 81%, and it is difficult to increase this value any further. Compared to the 3880mm gasifier, in the new project’s gasifier, when methane is controlled at 800 ppm, the carbon monoxide level is 2 points lower; meanwhile, the hydrogen content can reach 37%, and the carbon dioxide level is also relatively high. By appropriately reducing the oxygen-to-coal ratio, the carbon monoxide content increases, but it remains low compared to 3880 mm; the effective content is also low. At present, it is not clear whether this is due to operational issues, changes in the reaction conditions resulting from a larger reaction space in the furnace, or problems with the quality of the coal, which leads to poor gas production. Let’s discuss this together with experienced experts!
The low content of effective gases in the process gas, the low level of carbon monoxide, as well as the abnormal levels of methane and carbon dioxide can be caused by various factors, including the reaction conditions inside the furnace, the quality of the raw coal, and operational parameters. Here are some aspects that may need to be considered and adjusted: 1. **Coal quality issue**: - The quality and composition of the coal slurry directly affect the gasification efficiency. Check the quality of the coal slurry, including whether the fixed carbon content, volatile matter, moisture, ash content, etc., meet the design requirements. - If the source of the coal slurry changes, it may be necessary to adjust the process parameters for the new coal quality. 2. **Oxygen-to-coal ratio**: – Adjusting the oxygen-to-coal ratio appropriately can change the atmosphere inside the gasifier, thereby affecting the reaction equilibrium. Reducing the oxygen-to-coal ratio increases the amount of reducing gases (such as CO and H2) produced, but it may also increase the output of unvaporized carbon. - It is necessary to find the optimal oxygen-coal ratio to maximize the yields of carbon monoxide and hydrogen, while controlling the formation of methane and carbon dioxide. 3. **Nozzle design and arrangement**: - Whether the design and layout of the four nozzles ensure uniform mixing of coal slurry and oxygen affects the efficiency of the gasification process. - It is necessary to check whether the nozzle is worn or clogged, and to clean it or replace it promptly. 4. **Vaporization temperature and pressure**: - The temperature and pressure in the vaporization furnace have a significant impact on the reaction rate and equilibrium. Whether to maintain the ideal vaporization temperature and pressure requires adjustments based on experimental data and theoretical analysis. 5. **Control of side reactions**: – The formation of methane and carbon dioxide may occur as part of the side reaction process. It is necessary to optimize the operating conditions to suppress these side reactions, such as improving temperature control inside the furnace and adjusting the flow properties of the raw materials and gases. 6. **Quality of the gasifying agent**: - Check whether the purity of the oxygen used and the quality of the steam meet the required standards, as these factors can affect the efficiency of the gasification reaction as well as the composition of the gases produced. 7. **Residence time of materials in the furnace**: An increase in the reaction volume can lead to changes in the residence time of materials, affecting the completeness of the gasification process and the composition of the gases. 8. **Simulation and Experimentation**: – The gasification process can be simulated using simulation tools to predict the reaction trends under different operating conditions. - Tests were conducted on a small-scale gasification device in the laboratory to more accurately identify the problem. Finally, limitations in the equipment design, such as the reaction space of the gasification furnace and the gas flow dynamics, cannot be ruled out; these factors may also affect the composition of the gaseous products. Working closely with the design team at East China University of Science and Technology to analyze the differences between the actual operating data of the gasification furnace and the design expectations, and thereby optimizing the system, could be one of the ways to solve the problem. At the same time, it is also possible to draw lessons from other successful cases in the industry and conduct comparative analysis. .
If the operation is fine, recalculate the burner.
In the same case with methane, carbon monoxide is low, and the coal slurry is dilute
The slurry concentration is good, at 62-63%
Do any other experts have any suggestions?
What are the oxygen flow rates for the burner, specifically for the epoxy oxygen and the central oxygen?
I did a rough calculation of the flow rate; it’s around 3.5 m/s. This is at the oxygen shut-off valve, with an oxygen concentration of about 17.2% at the center
Flow rate: 17,000 cubic meters; pipe diameter: 6 inches; pressure: 69 kilograms; temperature: 24.4 degrees. The approximate flow velocity is 4.2 m/s, with an oxygen concentration at the center of around 17.2%
Flow rate: 17,000 cubic meters; pipe diameter: 6 inches; pressure: 69 kilograms; temperature: 24.4 degrees. The approximate flow velocity is 4.2 m/s, with an oxygen concentration at the center of around 17.2%