Discussion on trips caused by the burner cooling water system

The reason for the overreported high temperature at the burner outlet is not necessarily that the burner is damaged; a poor heat exchange efficiency in the burner cooling water cooler can also lead to an overreported high temperature of the cooling water entering and leaving the burner. In such cases, it is sufficient to increase the amount of cooling water used in the burner cooling water cooler to improve its heat exchange efficiency. For general burner failures, a 4-out-of-3 selection can be used to make a determination; this will trigger the interlock to close the self-regulating valves before and after the burner, thereby preventing gas leakage accidents.

The safety interlock on the burner is a three-out-of-two system (flow, temperature, and burner outlet pressure)! If the CO level is found to be too high, an immediate shutdown should occur

The purpose of interlocking is for safety reasons. If the burner really gets perforated, process gas will flow through the burner jacket and coils into the burner’s cooling water lines, then into the low-pressure pipelines and equipment, where it will eventually come into contact with air, leading to serious consequences! Therefore, in most plants, after the burner trips, the automatic control valves for the burner’s cooling water inlet and outlet close. Of course, if it is discussed in conjunction with the “3rd floor,” it would be better to select two out of the three interlocks related to \"low traffic, poor traffic, and temperature.\" This post was last edited by huaguiyi on 2008-3-19 13:19.]

The reason for setting a choice of three over two is to prevent larger accidents caused by the leakage of syngas due to the rupture of the burner coil. The burner cooling water return pipeline is also equipped with an on-line analysis alarm to detect the CO content in the return water and confirm whether there are any ruptures in the coils. This also adds an additional layer of security.

That is only the case for Texaco furnaces. If the burner coil of one of the multi-nozzle burners ruptures, should one pair of burners be shut down or should the system trigger an emergency shutdown? Should the front and rear cuts of the burner be closed after stopping the burner? One furnace, four burners – what a hassle! Texaco is still simpler to deal with when there are problems.

Anyway! The interlocks in the burner system are all for safety! When the Texaco burner is started in a 3-out-of-2 mode, the self-regulating valves before and after the burner close, thereby triggering the gasifier shutdown interlock! Otherwise, if a large amount of water enters the operating, high-temperature vaporization furnace, it is easy to imagine that this would result in a steam explosion! When feeding material into the gasifier, the interlock between the automatic control valves before and after the burner must be activated! Otherwise, the other interlocks in the burner system will be activated, and the self-regulating valves before and after the burner will not close either; as a result, the gasification furnace will not shut down! So an accident could happen! Personal opinion, definitely remember!

Upstairs, if the burner system trips due to interlocks, it is necessary to shut off the valves before and after the burner; in that case, there is no need for a cooling water tank for the emergency burner either. Since a failure in the burner cooling water pump will inevitably result in low flow rates and high outlet temperatures, shutting off the valves before and after the burner means that the cooling water tank for the emergency burner becomes redundant, right?

The friends on floors 7 and 8 are a bit confused. First of all, the burner coil has ruptured, which prevents water from reaching the gasification furnace; the pressure of the coolant water used for cooling the burners is much lower than the pressure in the gasification furnace. As a direct result of this rupture, process gas ends up entering the gas-liquid separator for the burner coolant water. One of our units was even overturned as a result of this, so please be aware that water cannot get into the gasification furnace. A failure in the burner cooling water pump also does not cause the upstream and downstream valves to close immediately, nor does it result in a high outlet temperature. When the pressure in the burner cooling water main is at LL, the standby pump starts automatically. When the main pressure reaches LLL, the emergency water valve opens. Five minutes after it opens, if the level of water in the emergency water tank is at LL and the emergency water valve has not closed, the valves before and after the burner cooling water system close automatically. So I hope everyone will still focus on solid foundations in their daily studies

I would like to ask the experts upstairs: Since the outlet temperature of the burner cooling water is generally not higher than 55 degrees, in my understanding, during normal operation the flow rate difference between the inlet and outlet of the burner cooling water should be zero； In the event of a fault, since there is a check valve at the inlet, the flow difference between the inlet and outlet of the burner cooling water is also zero. I don’t understand why the Desgu burner cooling water interlock has two logical conditions: “low low flow difference” and “high flow difference”.

Because if the cooling pipe breaks, gas will enter the water pipe, affecting the flow rate of the cooling water.

Let me explain why the outlet flow rate increases while the inlet flow rate decreases in the case of a burner coil leak: Since both of these flow meters are differential pressure flow meters, when there is a leak in the coil, the pressure inside the coil rises, which means the pressure difference before and after the inlet flow meter decreases, resulting in a lower reading for the inlet flow rate； As the pressure difference before and after the outlet flow meter increases, the corresponding outlet flow rate increases as well. The high temperature of the process gas at the outlet also indicates that high-temperature process gas has entered the coil, and this is not caused by a low amount of water used for burner cooling. This is purely my personal opinion; I hope fellow sailors can offer different views!

In the case of four nozzles, if a three-out-of-two interlock shutdown occurs for a single burner, only the burner that is experiencing the problem will have its valve closed; the others will remain open. At this point, the gasification furnace also shuts down. To handle this situation, the burners that are not having any problems can be handled as normal shutdowns, while the burner with the issue must be treated as an abnormal burner. Is this complicated?

In fact, the poster’s concerns are unfounded; a system shutdown caused by a fault in the burner cooling water will inevitably result in the automatic closure of the inlet and outlet shut-off valves (triggered by the ESD). If this does not happen, the process operator must manually close those valves to prevent cooling water from entering the gasifier. The poster is worried that the lack of cooling water protection for the burner head might damage the burner; in fact, after the system shuts down, the nitrogen valve for low-flow protection of the burner activates, thereby protecting the burner.

If what the original poster is referring to is a 2-out-of-3 series connection, I think the setup is incorrect: there should at least be high inlet pressure, right? As the poster mentioned, 1. The flow rate at the burner cooling water inlet is very low ； 2. High flow difference between the inlet and outlet of the burner cooling water ； 3. High outlet temperature of the burner cooling water: If there is a blockage in the burner cooling water pipes, or if the flow control valves at the inlet and outlet of the burner cooling water are set to a low opening degree, the inlet flow rate will be low, which inevitably leads to a high outlet temperature. Therefore, if a selection of three out of four is possible, it can be determined that there is a fault with the burner coil, and it is necessary to close the inlet and outlet valves of the burner. Is that guy from Cathay up there? I disagree with you; without burner cooling water, even with a low-flow nitrogen blowout, it is not possible to ensure that the burner will not get damaged!

How can the shutdown of the inlet and outlet shut-off valves of the burner be explained by an extremely low flow rate of the burner cooling water? In my opinion, the flow rate difference between the inlet and outlet cooling water should be zero under normal conditions, as the temperature of the outlet cooling water generally does not exceed 55 degrees. If a very low flow difference causes the shutdown, it will inevitably result in the burner cooling water system failing to operate.

The 3-out-of-2 parameters for the burner cooling water system are inlet pressure, inlet flow rate, and outlet temperature. During normal operation, an CO alarm generally does not result in shutdown; it merely serves as a reminder to the operators to minimize unnecessary monitoring, as the instruments may sometimes give inaccurate readings. When the burner is damaged, high pressure will leak into the low-pressure area. The outlet pressure of Pump 1 is lower than that of the gasification furnace, while the pressure in the return water tank remains at atmospheric level. As a result, high-pressure syngas will also enter, leading to an increase in the inflow and a decrease in the outflow, thereby increasing the difference between the inlet and outlet flow rates　

I think what is meant here should not be low import pressure, but rather a low or high pressure difference between inlet and outlet pressures. The emergency cooling tank is activated when the cooling water pressure drops below 0.45 Mpa. If the cooling water pump fails or the vaporization furnace shuts down, there will be no water available at the burners. Since this is not a burner failure, the valves before and after the burners will not close. The emergency tank can hold water for a certain period of time; during this time, you can restart the cooling water pump to ensure the burner’s service life.

Will the burner interlock cause the gasifier to shut down?

The reason why the cooling water pressure in the Texaco burner is lower than the pressure in the gasifier is to prevent the coiling from being burned through, which could lead to water entering the furnace and damaging the furnace bricks. It is a serious accident when high-temperature furnace bricks crack upon contact with cold water. The pressure in our plant’s gasifier is 65 kilograms, while the pressure of the cooling water for the burners, as well as the pressure inside the burners themselves, is 18 kilograms. Once the burner coil is burned through, high-pressure syngas will escape along the outlet pipeline, while the water in the inlet pipeline is held back by the high-pressure syngas.

Are you talking about the Texaco stove? The pressure inside the furnace is much higher than that of the burner cooling water; how is it possible for water to enter the furnace?