【Weekly Question】What are the common faults encountered in the roof reversal of coke oven gas collection tanks, and what are the key operating points? (December 6th---December 12th)
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This post was last edited by Desert Poplar on 2010-12-4 at 20:32. For the operation of coke ovens, the pressure in the gas collection tank is very important. Although adjusting this pressure is closely related to the operation of the fans in the gas purification system, the opening degree of the valves that connect the top of the oven to the gas pipes on the machine side and the coke side is also crucial. Here, please share the problems your unit has encountered in this regard as well as the solutions adopted. Everyone is welcome to participate; participants will receive generous rewards, and those who answer well will get even bigger prizes.
Our plant features a single gas collection pipe; the pressure in this pipe (120 Pa) is related to the opening degree of the roof flap and butterfly valve (as well as the distance from the blower). We use a computer control system to regulate the pressure in the gas collection pipe; each adjustment of the pressure takes 30–40 seconds, and the results are very good. The main parameters collected are the butterfly valve opening (one point per coke oven), the suction pressure before the primary cooler, the fan speed, and the pressure behind the blower; these parameters are set and controlled by a computer.
Our plant features a single gas collection tank on the machine side. Currently, the pressure measurement point for this collection tank is located in front of the automatic flap in the π-shaped tube; the pressure at this location is about 50 Pa lower than the pressure measured at the collection tank itself. Therefore, we recommend adjusting the process parameters. Change from 80–120 Pa to 80–100 Pa. As for the flap, I think it should be the same in all cases: a manual flap is installed at the upper part of the connection between the air collection groove and the π-shaped tube. In our factory, it remains in the fully open position and hardly moves ； Above the connection point between the π-type pipe and the negative pressure pipeline, an automatic flap is installed; this flap is controlled and adjusted from the fan room.
One of the coke ovens here has a single gas collection tank on the machine side. At present, the pressure measurement point for this collection tank is located in front of the π-shaped tube with automatic flipping function; there is also a manual butterfly valve behind the π-shaped tube. Generally, the automatic butterfly valve is controlled by a computer, and its opening degree is adjusted based on the pressure level, so as to maintain the pressure between 80–120 Pa. During coal loading, the pressure is kept around 40 Pa. When the automatic butterfly valve cannot perform proper control, the manual butterfly valve is used to assist in regulating the pressure. Generally, we rarely operate butterfly valves manually; they can be controlled properly using automated butterfly valves controlled by a computer. Parameters such as the suction pressure in front of the primary cooler and the pressure behind the blower are all set values, which are automatically controlled by a computer. The gas collection tank is divided into three sections, each of which is controlled separately and without interference from the others.
The pressure in our plant’s gas collection ducts is controlled automatically within the range of 100–120 Pa, with large-volume reflux control (automatic) being used to keep this pressure within the normal fluctuation range. However, in cases where coke oven operation is abnormal, manual adjustment is employed. The U-shaped valves in the gas collection ducts are adjusted automatically (or manually) to maintain an opening degree between 85 and 95%; in special situations, manual adjustment is used instead of automatic one. The most common problems are related to the instrument actuators, and these can be avoided through regular inspections
There seems to be another method of connecting two π-shaped tubes with pipes in order to stabilize the pressure in the gas collection pipe. I just haven’t seen it.
An N-shaped tube can be used, with one flap featuring automatic adjustment and the other manual adjustment; generally, automatic adjustment is used, while manual adjustment is employed in emergency situations
Our coke ovens here all have a single gas collection tank on the machine side; 4.3-meter coke ovens use one gas collection tank, while 6-meter coke ovens utilize two gas collection tanks with dual suction pipes. The pressure measurement points for the gas collection tanks are located on these tanks themselves. The suction pipe section of the π-shaped tube is designed to adjust automatically, and there is a manual butterfly valve in the positive-pressure section of the π-shaped tube. Generally, the automatic butterfly valve is controlled by a computer, with its opening degree adjusted based on pressure levels. The normal operating pressure range is 80–120 Pa; during coal loading, this value can reach around 160 Pa. When there are significant changes in operating conditions or when the automatic butterfly valve loses control, the manual butterfly valve is used to assist in regulation. Generally, we rarely operate butterfly valves manually; they can be controlled properly using automated butterfly valves controlled by a computer. The pressure in the gas collection tank and the suction pressure before the primary cooler are both adjusted in the blower room, with automatic control via a computer.