How should operations be carried out when the compressor in the catalytic unit is started without using a flare?
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During each start-up of our catalytic unit, the compressor has to vent gas through a flare, producing thick smoke that has caused great dissatisfaction among the residents in the surrounding area; therefore, we want to switch to a system that does not use flares. So how should it be done? What are the precautions?
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When injecting reactant fuel, increase the medium-pressure steam pressure. The turbine was spun up to over 4000. Stable oil recovery is complete; heating steam is introduced to the reboiler at the bottom of the separation tower to increase the temperature and pressure. The middle section of the fractionation column is filled with diesel. After feeding, it is quickly integrated into the pneumatic compressor; once the pressure reaches 8 kilograms, integration is completed and stabilization occurs. Increase temperature and pressure to establish a three-tower cycle. A mid-stage heat source is introduced into the stabilizer bottom reboiler. . . . . Be sure to control the rebound momentum well and respond to pressure smoothly. Prevent surge.
1. The absorption and stabilization system introduces gas to displace air, pressurizes the system, and introduces gasoline to establish a three-tank circulation； 2. After removing the large blind plate from the distillation system, introduce gas for displacement and collect oil to establish a three-way circulation ； 3. When installing the catalyst in the reaction regeneration system, the rich gas compressor begins to warm up; at this time the anti-surge valve is fully open. To prevent surging in the unit, the control valve for the liquid level at the bottom of the reabsorption tower is opened slightly ； 4. Before switching the catalyst, increase the compressor speed to its minimum controlled speed. During this process, if the pressure at the compressor outlet is higher than that of the stabilization system, open the outlet valve to connect it to the stabilization system. Control the compressor inlet pressure by adjusting the opening degree of the reabsorption tower bottom liquid level control valve, in order to prevent compressor surging ； 5. As the amount of fuel injected during the reaction increases, gradually reduce the opening degree of the liquid level control valve at the bottom of the reabsorption tower and the opening degree of the backflow valve, while increasing the compressor speed.
The last edit to this post was made by fengdingwen on 2010-10-7 at 11:02. Reply 4# xdx: 3. When installing the catalyst in the reaction regeneration system, the rich gas compressor starts up for warming up; at this time, the counterflow valve is fully open. “To prevent surging in the unit, the control valve for the liquid level at the bottom of the reabsorption tower is opened slightly.”； ” 4. Before switching the catalyst, increase the compressor speed to its minimum controlled speed. During this process, if the pressure at the compressor outlet is higher than that of the stabilization system, open the outlet valve to connect it to the stabilization system. Control the compressor inlet pressure by adjusting the opening degree of the reabsorption tower bottom liquid level control valve, in order to prevent compressor surge ； ” What do these two mean? Is the reabsorption tower related to compressor surge? Is the reabsorption tower not equipped with diesel at this time? Let the dry gas from the absorption stabilization system enter the distillation tower and then proceed to the compressor inlet, right? Does the overhead vapor separator of the fractionation tower not have a purge gas line?
1. Before switching to the catalyst, increase the compressor speed to its minimum controlled speed. During this process, if the pressure at the compressor outlet is higher than that of the stabilization system, open the outlet valve to connect it to the stabilization system. Control the compressor inlet pressure by adjusting the opening degree of the reabsorption tower bottom liquid level control valve, in order to prevent compressor surging； The process is: compressor outlet — absorption tower — reabsorption tower — reabsorption tower bottom liquid level control valve — fractionation tower — compressor inlet. To ensure normal circulation of the rich gas, a control valve for the liquid level at the bottom of the absorption tower is used to regulate the inlet pressure of the machine, as high outlet pressure can easily cause compressor surge.
I’ve learned it, but isn’t the principle behind using the reabsorption tower bottom liquid control valve to regulate the outlet pressure and prevent reverse surging at the compressor outlet different? Why not use the outlet anti-surge line to control the outlet pressure?
Reply to 6# aqhjh0159: 1. Is it a bit early to turn on the compressor before switching the catalyst? Moreover, at that time the various parameters were extremely unstable, and the compressor was prone to surge. 2. The flow sequence of the circulation circuit is correct, but isn’t it very difficult to control the reaction pressure and the differential pressure between the two regulating devices after reactant injection, which in turn increases the stability challenges for the entire system?
Our unit’s stabilizer bottom reboiler has only one heat source of medium temperature, with no steam used as a heat source. Therefore, at the beginning of operation, the circulation temperature in Unit 1 is low and the volume is small and unstable (frequently under vacuum); could this result in the vapor pressure of the stable gasoline not meeting the specifications? It seems that it will still be quite difficult for me to start up the unit without using a flare; I need to take things slowly.
It’s unlikely to avoid using torches altogether; focus on the following points: 1. Pre-warm the unit in advance； 2. Once about 20 tons of feed have been added, increase the speed, enter the transcritical mode, fully open the counterflow valve, and open the stabilization valve. 3. Close the outlet of the compressor and direct the flow to the flare; control the pressure in the settler using the counterflow mechanism. Since the pressure in the stabilization system is very low, it’s equivalent to allowing low-pressure venting at the compressor outlet. Meanwhile, increase the speed and pressure, and make adjustments so that the system can be integrated into the stabilization system before the flare output becomes too high. In my opinion, the diameter of the control valve for the bottom liquid in the reabsorption tower is too small; it is insufficient to counteract the backflow at the compressor inlet, and thus it cannot ensure that the unit does not experience surge
The reabsorption tower bottom liquid level control valve is adjusted according to actual needs (when the counterflow valve is fully open, the unit still experiences surge). It is not necessary to open it if the unit is not surging.