Tell me when your low-flow line for the recycle hydrogen compressor is activated, and has it been activated before?

Are you referring to the anti-stall line (return line, minimum flow line, counter-rotation)? The equipment technicians requested that it remain running continuously; later, for the sake of increasing the circulation rate and saving energy, the operation level was gradually reduced, but 10% of the capacity was still kept.

Keeping it on all the time doesn’t it consume a lot of energy? And if it’s kept running, the processing capacity won’t increase, right? The amount of circulating hydrogen entering the reactor decreases, which is dangerous for the catalyst.

What everyone is referring to is probably the low-flow bypass for recycled hydrogen! We didn’t start it at first; later, in order to increase the temperature at the outlet, we opened the bypass valve to adjust the flow rate of circulating hydrogen at the compressor outlet, keeping this flow rate above the minimum value specified in the design. Ensure the reaction outlet temperature. The opening degree is over 30%. Our heat exchangers aren’t effective; even when the heating furnace is operating at full capacity, the output volume doesn’t increase.

Here, normally we need to activate the anti-surge function at the time of startup; once the system is running properly, it’s not necessary anymore. Due to some internal leakage in the return line, there is no way to control it.

Our anti-surge control valve has always been set to automatic mode; it seems it has never been switched to manual mode

This post was last edited by lijianhuai on 2011-8-30 21:00. I work with equipment; I specialize in oil refining processes. The anti-surge control valve of the circulator must not be closed during startup – this is a logical requirement as it serves as a protection mechanism to prevent surge from damaging the unit. After operation begins, this valve should be gradually closed manually based on the flow rate; ultimately, switching to automatic control is the safest approach, as it results in the least disturbance and fluctuations for both the unit and the reaction system. Previously, in order to ensure that the unit did not surge while also maintaining the process flow rate, the inlet flow rate was increased at the expense of higher energy consumption by the drive motor, which caused the surge valve to close completely and then remain open at a setting of 10–15% (in practice, there was still about 10% of opening when the valve was completely closed in the field). Now, to meet the needs of energy saving and consumption reduction, new control systems are available that can quickly detect the backflow signals preceding surge, thereby automatically controlling the opening of the anti-surge valve, eliminating the need for the previous limit mechanisms. As a result, the energy consumption for driving the unit decreases, and the anti-surge valve closes completely automatically, thereby ensuring that the unit does not experience surge while also minimizing energy consumption. It has been operated before; as the composition of the DCS inlet stream becomes lighter, the flow rate decreases. Based on the position of the operating point on the performance curve, if that point is close to the surge line, the valve will automatically open quickly and close slowly. It is also possible to switch to manual operation of this valve in order to meet the flow requirements at the machine inlet and keep it away from the surge region. However, an excessive return increases the inlet volume, which reduces the reaction volume; as a result, it is necessary to increase the speed of the drive motor to meet the process requirements, thereby wasting drive energy in order to satisfy the safety needs of the unit. If the surge valve is under automatic control, it will open quickly and close slowly, resulting in undesirable fluctuations in system temperature.

On our end, it was turned on when we started using it, but it has been off ever since!

It seems that aside from being consistent at the start of work, everyone has their own methods at other times.

It is the “stall prevention line”; generally, it operates in automatic mode, with the DCS making adjustments as appropriate. In many hydrogenation units in China, it is possible to activate such a \"bypass.\" The main reasons are: 1. It is related to design costs; 2. There is a significant difference between the designed capacity and the actual amount of material processed; 3. At the beginning of the reaction process, the severity conditions are low, resulting in a low flow rate of recycled hydrogen; 4. In refineries located in the north, the properties of the raw materials are likely to be better; 5. Other factors

It is fully open at startup, then gradually shuts down, until it is completely closed