The annual anti-freezing work is complete; let’s discuss the problems that occurred during winter

The acid gas line tends to get clogged due to crystallization; after steam purging, condensate flows into the acid gas separator tank. Inadequate drainage can cause freezing and deformation at the manhole of the tank. The liquid level in the reflux tank at the top of the diethanolamine (used for dry gas liquefaction desulfurization) regeneration tower is low, and the reflux pump operates intermittently, which makes it easy for the pipelines to freeze. In addition to conventional heating, we added a water supply line to the reflux tank so that the reflux pump can run continuously; however, attention must be paid to the solvent concentration. The heating wires connected to most glass gauge levels do not work properly and allow steam to leak. Last edited by wdepei on 2009-3-19 12:10

In the coking cold coke water air coolers, flow imbalance caused 3 out of 8 units to crack due to freezing; fortunately, it was the plug plates that were damaged and the tube bundles were not affected – thank goodness! Lol. I would like to remind my colleagues that in cases where there is water leakage in air coolers, it is essential to avoid flow imbalance. This is especially important during winter, when it’s necessary to check and monitor the equipment regularly to prevent it from cracking due to freezing.

When the weather is especially cold, be sure to check the pump frequently.

It is advisable to install a backflow device at the steam dead end to facilitate drainage

Hehe, I’m envious that you’ve finished your antifreeze work so early; it’s snowing again here, and I guess we’ll have to wait until mid-April to finish it； The problem we are facing is that pipelines that extend across boundary areas, such as those used for transporting liquid hydrocarbons, experience freezing due to a lack of attention paid to their inspection. This year, efforts to inspect these pipelines have been increased, with inspections required to be carried out every day during the daytime shift ；

The drain valve isn’t working well, so I have to vent the pressure; it seems a bit wasteful. I was wondering if anyone has any good suggestions.

If the circulating water in the atmospheric and vacuum distillation units is not treated after shutdown, it will freeze in the winters of the northern regions, causing pipeline freezing and cracking, which is quite difficult to deal with! ! ! If the bypass lines and steam vent points in winter are not set properly, it can lead to freezing and pipeline rupture! ! In the vacuum system of atmospheric and vacuum distillation, the side lines and residue (asphalt) are prone to freezing; this applies also to the instruments, so it’s important to keep these areas insulated!

(1) Before winter arrives each year, inspections and maintenance measures to prevent freezing and condensation should be carried out on the equipment, to ensure that all steam traps are functioning properly, that all heat tracing systems are unobstructed, and that the glass in all workshops and pump rooms is intact. (2) Formulate anti-freezing and anti-condensation plans and measures based on the actual situation. (3) Prepare the steam and activate the process pipeline trace heating. (4) Connect to the instrument and activate the instrument system’s heat trace. (5) For the heat tracing lines that are not in use or can be used at any time, use air to blow out any water accumulated inside them, and fully open the inlet and outlet valves for backwashing. (6) Check whether the root valves for fire suppression steam and purge steam are tight; if they are tight, close the root valves and open the end valves ； If it is not tight, replace it. (7) Open the inlet and outlet valves for the cooling water of the sampler equipped with a cooling system to ensure water circulation. (8) Drain all the water accumulated in the lines that are not in use. (9) The inlet and outlet connection valves of the water cooling equipment should be slightly opened to ensure an adequate supply of water. (10) The cooling water system for the standby unit is put into operation. (11) The workshop conducts regular inspections to ensure proper anti-freezing and anti-condensation measures, and the work teams consider these measures to be an important part of their routine inspections.

The dry gas pipeline that carries our product over long distances and includes many sections with elevation changes means that when the weather is cold, the pressure of the dry gas in that pipeline drops to zero; only then do we realize that the pipeline has frozen due to water inside it. So we promptly installed heat tracing, and now the situation is much better! !

The hydrogenation unit was temporarily shut down in December of this year. During the restart process, due to operational errors in the downstream workshops, the acidic water line of my unit was closed, resulting in hundreds of meters of acidic water freezing. It took 30 hours to resolve the situation – it was truly a painful experience. The liquefied gas line in the reforming unit often freezes due to water present in the liquefied gas, coupled with the lack of heat tracing in that line.

On that day when the temperature was minus 20 degrees, a hydrogen valve in our installation froze and cracked, causing hydrogen to leak out rapidly. Fortunately, it was addressed in time; otherwise, the entire system would have been damaged. Special attention must be paid to the ends of pipes that do not have flow of water – even if no water is flowing through them normally, water can still accumulate there. As this water keeps accumulating at the ends of the pipes, it can eventually cause them to freeze and crack.

Nothing serious happened to us; there were no pipe freezes. What did occur was leaks at the heating threads of many instrument pipelines, and basically all of the condensate water from the steam was released, which is a great waste! ! !

An incident from this winter. At our facility in the North (the catalytic unit), a steam line for atomization at one of the nozzles in the gasoline assist riser froze and developed a crack. It was later found that this nozzle was blocked, and it is suspected that this was caused by a significant fluctuation in steam pressure. After it became blocked, no attention was paid to it and inspections were neglected, which led to the freezing and cracking. Lesson: In winter, it is necessary to check for freezing points not only, but also to increase the inspection intensity of areas that are not considered critical, depending on the actual conditions.

Cooling water flow deviation in coking cold coke cooling caused one unit to freeze up. In the future, during winter, remove one of the air coolers, clean it with air, which helps prevent freezing and saves electricity

We direct the vented heating steam and condensed water to the deaerator. The constant leaks in the heating wire plugs are indeed a major problem; this is what worries us the most this winter. Also, special attention must be paid to the slurry pipelines; we had to replace all of them with new ones after the external lines of a neighboring company froze over. We have also encountered situations where the polymerization section of the slurry line became blocked; even after cutting out the affected pipe section, it couldn’t be cleared using steam or iron rods. Therefore, it’s essential to keep the temperature at the bottom of the distillation tower under control

Every winter, one or two level gauges crack due to freezing; the inspections aren’t thorough enough

There are not enough spare parts for steam traps, and many of them leak steam, resulting in significant waste； Stricter controls are implemented for instrument heating; some units experienced shutdowns due to instrument freezing, which led to casualties.

It’s been cold here for a few days, but the equipment hasn’t been damaged by the cold

The bottom quick-opening valve of one of our fire water vertical pipes has frozen and cracked. The pipe is an isolated one, not connected to any other pipes; it is likely that the bottom quick-opening valve remained closed for a long time, and water was not drained after its last use.

Nothing major happened to us; there was no freezing and cracking of pipes. It was just that the heating wires on many instrument pipelines leaked