Problems with coke oven gas preheaters
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The pressure difference before and after the valve of the gas preheater in our workshop is 1200 PA. I would like to ask whether such a pressure difference is normal. Today we opened the preheater to take a look; the condition at the valve and at the lower part of the preheater was normal. Additionally, when the valve before and after the preheater were closed and a bypass was used, the pressure difference remained normal. Everyone, please share your thoughts on what could be causing this.
This should be directly related to the preheater resistance; it’s necessary to analyze the issue with the preheater (I’m not sure what type of construction it has in your case). Our pressure difference before and after is within 500 Pa; although there have been times when the pressure difference was higher, this was caused by deposits inside the preheater.
With such high resistance in the preheater, it’s definitely because there’s a blockage in the pipes inside. Try steaming them thoroughly; if that doesn’t work, then it will be necessary to carry out major repairs.
The structure of preheaters should be the same: gas flows through the tube side while steam flows through the shell side. High resistance is usually caused by blockages in the tube side; if steam cleaning does not work, it is necessary to open the preheater and manually remove the deposits inside.
Let me tell you a method: when performing maintenance by blocking the blind plate, use a bamboo stick to poke at the bottom area and pour water from above; be sure to pay close attention to safety. Finally, use steam to check for leaks
Generally, the pressure in preheaters does not exceed 500 PA; here it is around 1000 PA as well. There are many reasons for this, and a more in-depth analysis is needed