How to deal with organic impurities in 2-inch natural gas pipelines
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Dear all**, our plant has a gas pipeline that leads from behind the outlet of the separator (demister) to the gas turbine as fuel gas. Recently, the flow passage in this pipeline has been gradually becoming blocked; the substances discharged from the separator are black powdery impurities that are sticky and may contain oil. Preliminary analysis indicates that these substances are mostly organic in nature, with little residue remaining after burning, and smoke is produced as well. My question is: 1. How can we remove the impurities from the pipeline without affecting its operation?； 2. How to remove impurities offline. 3. Can tapping the pipe improve its flow efficiency? 4. Can some impurities be removed by using heated pipes? . Thank you all, reward_7ree
It is preliminarily determined that the gaps in the separator (demisting screen) are too large, preventing effective removal of liquid polycyclic aromatic hydrocarbons. It is recommended to modify or replace the separator (demisting screen) in order to reduce these gaps; at the same time, steam heating (at a temperature of 150 degrees) should be applied to that section of pipeline. After observing the results, further evaluation and corrective actions can be taken.
This situation occurs in vent pipes over time, especially in long pipes. The transition between winter and summer, as well as changes in temperature throughout the day, can lead to the formation of condensation. Additionally, changes in flow rate and the start/stop of operations can also result in the inclusion of impurities. It seems that the design of your pipes is a bit too small; under normal circumstances, this kind of situation does not cause pipe blockages. It is recommended to add a filter (one in use and one as a spare), filled with molecular sieve and ceramic balls.
Because the natural gas flow on my end isn’t very high either. And for processing online, at least some improvement is desired. 2-inch gas pipelines are equipped with a Y-type filter.
A low-level discharge tank is connected to the separator’s drain line; a heat tracing tube is installed along this drain line, along with a heat tracing banana tube through which condensate is passed to reduce viscosity. The discharge tank is equipped with heating steam, and steam is supplied as needed based on the level of material in the tank, similar to how it is done in gas pipelines. This connection can also be made at the pipeline’s drain line. For the separator, it depends on whether discharge is done periodically or continuously; the timing of vaporization in the discharge tank is determined by the materials introduced.
Use the old method: add a filter and clean it regularly
Filters may not necessarily solve the problem; the key approach is to use pipe heating to raise the temperature and prevent organic substances from condensing into a liquid state. However, over time, these substances will still gradually accumulate within the pipes. Therefore, it is possible to install a buffer tank in between – there, the flow rate decreases, allowing these substances to settle inside the buffer tank, and the tank can be cleaned regularly.
Is it because there are too many impurities in your natural gas source? The cause still needs to be identified first, as dealing with this issue regularly is time-consuming and labor-intensive
In the case of treated natural gas, this kind of liquid condensation and coking occurs very rarely, and it is unclear what the main cause is. The black substance produced is likely not polycyclic aromatic hydrocarbons; otherwise, the combustion would not be complete. It is recommended to start by checking the gas source to find out the main cause. Online removal is not recommended, as it may affect the subsequent turbines.