The cyclone dust collector is producing too much waste material
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After the fixed-bed gas generator is loaded (oxygen flow of 1600 Nm3/h), too much material is carried away by the cyclone dust collector – including particulates and unreacted coal particles. What are the reasons for this, and how can it be addressed? Thank you.
In a fixed-bed reactor at atmospheric pressure, the gas space velocity in the gasifier is very high. If my estimates are correct, when the oxygen supply is 1600 Nm3/h, the gas production rate should be a little over 8000 Nm3/h. At atmospheric pressure, the gas flow rate should be above 22,000 m3/h. If the height of your furnace is 2.8 meters, this results in an air velocity inside the gasifier of over 1 m/s – a very high value – which means that the amount of ash carried away is also large.
What level are you at currently? If it’s level 1, try going up one level
Cyclones have certain requirements regarding the gas velocity at the inlet, the amount of solids, and the particle size distribution; the process parameters chosen during design are generally sufficient. The current challenge with cyclones is the design of those operating under high temperature and pressure; there are no major issues with cyclones that operate at normal pressure, low pressure, or high temperature. It is recommended to refer to the process design parameters and make flexible adjustments
1. Check whether the material leg of the downward cyclone separator is unobstructed. 2. Calculate whether the gas velocity entering the downward cyclone separator falls within the optimal range required for that cyclone separator. 3. The solid content entering the cyclone; if it exceeds the design requirements, poor separation will also occur.
Currently, the operating pressure of the gasifier is around 20 KPa. Based on a consumption of 230 units of oxygen per thousand cubic meters of gas, it is estimated that the gas flow rate is 7000 Nm3/h. For a 3.2-meter gas generator, is the space velocity 7000/3600/8=0.25 m/s?
I forgot to make the conversions using the PVT equation. The key issue is that the particle size of the coal fed into the furnace cannot be guaranteed, and there are no methods to determine the thermal stability of the raw coal. What comes out of the cyclone is coal in the form of small particles, and the drainage pipes and gutters are severely clogged. That’s so tiring! !
The main problem still lies in the accuracy of the dynamic separation design of the cyclone separator. Cyclone separators belong to the category of dynamic separators, and their system platforms require precise computational design using advanced dynamic separation techniques in order to ensure accurate and complete design. Domestic enterprises and universities often lack platform systems for the computational design of international precision dynamics separation technologies; they rely on textbooks to come up with rather rough technical solutions through \"rough estimates\" or even \"guesswork\", which inevitably results in a significant gap between the actual operating efficiency of the cyclone separators designed and the requirements of the process technology. Cyclone separation technology relies primarily on the differential centrifugal force generated by the difference in kinetic energy and momentum between different substances to achieve efficient separation. The efficiency of this separation process is influenced by factors such as operating temperature and pressure, gas phase composition, gas phase density, gas phase linear velocity and rotational angular momentum, gas phase viscosity, solid phase density, and the amount of material carried along (and in the case of a liquid phase, also by liquid phase density, liquid phase viscosity, liquid phase surface tension, etc.). Regarding the intuitive understanding of flow velocity, which is of great interest to everyone, both the linear velocity of the airflow and the values of the angular momentum constraints should not be too low nor too high ； If the streamline velocity and angular momentum are too low, gravity-driven sedimentation separation occurs, resulting in a significant drop in separation efficiency ； If the streamline velocity and angular momentum are too high, the separated particles will be carried away again by the airflow, which likewise leads to a significant decrease in separation efficiency. Professional dynamic separation technology companies all need to rely on precise dynamic calculations to design system platforms in order to achieve accurate results; this is often a technical rigor that domestic enterprises and universities lack. As is well known, under the same process conditions, the smaller the rotation radius of the airflow, the greater the rotational angular momentum, resulting in higher separation efficiency and greater operational flexibility. Currently, the rotational diameter of multi-factor cyclone mother-son separators widely used internationally does not exceed 50 mm; compared to conventional standard cyclone separators, whose design involves diameters measured in meters, the separation efficiency of these separators is significantly lower. Therefore, upgrading to the multi-factor cyclone parent-separator technology to replace traditional cyclone separators offers significant advantages in terms of improving separation efficiency, enhancing operational flexibility, and reducing operating costs. For technical information on improved cyclone separators and multi-factor swirl separator technologies, you can visit http://bbs.hcbbs.com/thread-1614524-1-1.html, http://bbs.hcbbs.com/thread-1655174-1-1.html, and http://bbs.hcbbs.com/thread-1637026-1-1.html to participate in discussions on cyclone separator technology and obtain more information.