Strange ammonia production

I have encountered fluctuations in ammonia production several times; our output is low, and the management unanimously believes that it is due to the ammonia synthesis tower. Our hourly ammonia production is around 17.0 tons, and this figure is measured by the ammonia storage unit. Once, while I was on night shift, the pressure, temperature, liquid level, circulation rate, and amount of supplementary gas in the synthesis system all remained unchanged, yet the ammonia storage unit reported a production volume of 14 tons. The dispatch team became very worried and called our managers from their homes. When they arrived, they scolded the crew on duty, and afterwards the production volume returned to normal. The managers said it was caused by operational errors. I shared the same feeling as the person who posted this question – it seemed like nothing could fix the situation. This phenomenon also occurred in other shifts, and it almost always happened during or after rain in the summer. But at other times as well, the production level has suddenly dropped; to this day, the reason is unknown, and the instruments indicate that there is nothing wrong with the flow meter. Another time, the indicator of the secondary gauge on the level gauge in the ammonia storage tank was giving inaccurate readings. The operator in the ammonia storage area did not go to the site to check the level; only 3 tons of ammonia had been produced when the flow meter indicated that amount. The storage area reported this figure to higher authorities. Later, the team leader went to check and found that the secondary gauge was showing a lower level, and the pneumatic valve was not opening, so all the ammonia remained in the buffer tank. This post was last edited by snowdfr on 2009-2-25 12:56.]

In a situation like the one you described, based on my analysis, the output of one class will be either higher or lower. Under normal circumstances, the output would not experience such large fluctuations. If such a situation occurs, it means that the liquid level in one of the ammonia separation tanks in the refrigeration system has also changed.

Personally, I think that if the production process, operating volume, and ammonia cooling/adding are all normal, it is still a measurement issue. Our ammonia storage tank is a 400-cubic-meter spherical tank, which is greatly affected by temperature, especially during long nights. Night falls.

There are several ways that can affect production: 1. If the methane synthesis rate is kept high, it may not seem like there’s any problem with the synthesis process, and the operation might even be more stable than usual, but the production volume remains low. 2. Sudden heavy rain can also increase ammonia production, as the system’s separation and condensation functions work better in such conditions. 3. Even if the number of compressors remains unchanged, a lower gas delivery rate can still affect production. 4. In case of sudden changes in production levels, first check the instruments; then consider the reasons mentioned above

There are many reasons for low ammonia production; if it’s due to issues with the instruments, it has little impact on the balance between ammonia production and supply. What I encountered was a sudden increase in ammonia production that was abnormal – it’s indeed difficult to explain.

The liquid ammonia refrigeration system has little to do with our ammonia production system. The ammonia separation tanks at various stages in the synthesis circuit are always emptied to zero level at the time of shift handover; this is done in every shift. No one wants to leave ammonia in the separation tanks and hand them over to the next shift.:lol

The measurement of ammonia tanks is indeed affected by temperature. This is because the weight of ammonia tanks is determined based on volume, and the specific gravity is calculated using a fixed value of 0.633 kg/l (at 4 degrees). Since the temperature during the early shift is always low and never high, the ammonia production is also affected in such a way that it remains low

1. We have a set of membrane separation systems for hydrogen recovery. Given the tight constraints in the gas production process these days, we try to maximize hydrogen recovery to keep the methane content at its lowest level possible. However, it still cannot fall below the factory’s specified limit of 14%. In other words, in order to alleviate the pressure on gas production, the methane level is kept steadily at 14% throughout. As a result, this does not affect fluctuations in ammonia production.

2. We use a combined alkali production process, and currently we are using the concentrated gas method for alkali production, which requires a large amount of ammonia. Therefore, we need to purchase large quantities of liquid ammonia on a daily basis. This means that there is an ample supply of liquid ammonia available for use in the synthesis process, so the temperature required for ammonia cooling is always maintained, regardless of weather conditions (whether it’s raining or sunny). Due to the high volume of ammonia used, the cooling temperature remains below -15 degrees Celsius. Going any lower has little impact on the efficiency of ammonia separation.

3. In terms of gas consumption, when the ammonia production is converted into tons of ammonia per unit of gas consumed, our consumption is much lower than usual (3100 Nm3/TNH3). Our equipment is relatively old, so achieving a gas consumption of 3300 Nm3/TNH3 is already considered good; sometimes it can even drop to 3100. But it’s impossible for the gas consumption in my shift to be significantly lower than that in the shifts before or after it.

4. The same applies to the instruments used. It’s unlikely that all the instruments work properly in the previous shifts while they start giving abnormal readings in my shift. There’s no such thing. Moreover, I calculate the ammonia production every hour, and the value is quite high each time.

I’m not very familiar with the manufacturing processes at the owner’s company, but we have encountered similar problems as well (producing 1500 T per day). In most cases, it’s a matter of measurement issues; temperature has little impact on this. I hope the owner can identify the cause as soon as possible and provide everyone with a definite answer~

The liquid level control in the separation tank is set too low; ammonia carried with gas passing through the flow meter affects the accuracy of measurement.

Do you use flow meters or ammonia tanks for measurement? In the case of flow meters, you can work backwards based on the consumption of products in subsequent processes. If the consumption remains unchanged, it’s a metering issue; if there are significant changes in consumption, there may be a problem with your production volume. If it’s about measurement, you can check the production volume from your previous shift as well as the liquid level in the ammonia tank. Also, see if there is a significant change in the ammonia tank’s liquid level within 30 minutes to 1 hour after you take over the shift. If gas leakage and ammonia release occurred during the handover from the previous shift, then the readings you get upon taking over are likely inaccurate.

It must be that the gauge used to monitor traffic suddenly spiked......... My supervisor encountered this issue when working on the methanol tower before; the dispatchers got panicked when it came time to report production levels.................................................

We don’t have flow meters installed for measuring production volume; therefore, the production amount is determined based on the readings from the storage tanks. Meanwhile, the ammonia added to the ammonia cooler passes through a flow meter. Currently, the production volume per shift is higher than usual. Apart from the high readings on the instrument (the ammonia flow meter), it’s hard to understand why this is happening. If the production volume really has increased, our boss will be laughing his head off. (Currently, the consumption of semi-water gas per ton of ammonia is only 2900 standard cubic meters.)

The issue with the instruments should be investigated by the instrument maintenance team. The ammonia addition flow rate is measured using a regular vortex flow meter along with an integrator; yet even after checking for days, no problems were found with the instruments. I’m really lucky—that my shift happened to be the one where the instrument readings were too high. The manufacturing center even suspected that I had damaged the instrument, and the production volume for that shift was treated as part of the regular workload. It’s not about questioning the production volume at all; it’s clearly a attempt to question my integrity! How can I work in a team where there’s no trust? It’s one thing if no one recognizes my abilities, but how can they insult my character? I think I’d better go look for a new job in the recruitment section. Please help me out by providing some relevant information, everyone!

Everything is normal; there are many reasons for any disruptions, and the specifics are even more complex. If errors occur occasionally, just treat them with a normal attitude – that’s how production works. This kind of thing happens in many units, especially in winter.

Thank you! Production should be approached with scientific rigor. Winter is indeed favorable for ammonia synthesis, as lower temperatures result in a significant increase in the air delivery capacity of blowers and compressors. The temperature required for ammonia cooling during the synthesis process is also more easily maintained. A consumption of 3100 or 2900 cubic meters of semi-water gas per ton of ammonia falls within the normal range; many manufacturers are able to achieve a consumption of 3100 cubic meters of semi-water gas per ton. It’s possible that our management level has reached a new height!:victory:

1. Reasons related to instrument measurement (affected by weather, accidental failures, etc.). 2. Reasons related to operation; it was mentioned on the 7th floor that the liquid level should be set to zero, but it’s not clear whether that really represents the zero liquid level. It’s possible that the liquid level is truly empty, which causes air to enter the system; not just 3 tons – 30 tons as well. I’ve seen this happen before.

Apart from instrument-related issues, there is indeed no more compelling explanation. The problem is that we purchase liquid ammonia externally, and this liquid ammonia enters the system through an ammonia flow meter; the readings from the meter match the weight of the liquid ammonia, which shows that the meter readings are accurate. The level gauge is set to zero, and gas is indeed present in the mixture, but the ammonia-producing process does not involve these instruments, so this factor can be ruled out.