What safety standards must be met by the equipment for desulfurization and denitrification of coke oven flue gas?

Strong support; everyone is welcome to discuss

Is thermal standby required for the coke oven chimney after desulfurization and denitrification of coke oven flue gas? 1. The impact of desulfurization and denitrification accidents on coke oven production: Accidents inevitably have an impact on coke oven production, especially those that occur suddenly, whose effects can be severe; this is precisely why some companies consider having backup systems for the heat emission from coke oven chimneys. It’s understandable, but whether hot standby is useful is debatable. 2. Feasibility of hot standby for chimneys: The principle of operation of a chimney is that the density of the hot smoke inside the chimney is lower than that of the outside atmosphere; this gives the hot smoke an upward buoyant force. Driven by the difference in atmospheric pressure and density, a negative pressure, or what is known as suction, is created at the base of the chimney. The purpose of chimney hot standby is to maintain suction at the base of the chimney at all times, as during normal operation. Therefore, hot flue gas is needed to be supplied to the chimney. The hot flue gas supplied can be hot air or other exhaust gases. It should be noted that the physical properties of both hot air and other thermal waste gases are almost identical to those of the gases generated during normal coke oven operation. In other words, the chimney’s hot standby feature ensures that it has a suction force similar to that during normal operation, with a smoke flow rate that is almost identical to that in normal operating conditions. 3. How to operate in the event of sudden accidents related to desulfurization and denitrification: Even if the chimney has sufficient suction capacity as a backup, it is not possible to shut down the desulfurization and denitrification systems or to switch the flue gas flow instantly in the event of an accident. Sudden accidents are unpredictable; a feasible technical measure is to implement interlock control between the desulfurization and denitration units, the coke oven heating exchange system, and the exhaust gas system. Enterprises should establish emergency plans and operating procedures for unexpected incidents. 4. Thermal standby for chimneys requires substantial energy consumption; the hot smoke generated by the standby system inevitably consumes a large amount of thermal energy. 5. Hazards of flue gas after SCR desulfurization and denitrification passing through the chimney: The desulfurization and denitrification exhaust gas, saturated with water vapor from the ammonia solution used in wet desulfurization and denitrification, is subject to dew point corrosion when it passes through the chimney. Only by using flue gas reheating can dew point corrosion be prevented.

As far as I know, in most current cases of flue gas desulfurization and denitrification in coke ovens, a backup chimney system is used, with hot air generated by heat exchangers; the required temperature for this air is between 130 and 150 degrees, and the volume of air flow is roughly 30,000 to 50,000 cubic meters

Supported. Hot standby for flue gas desulfurization and denitration stacks

1. It is necessary to consider having a hot standby chimney, as this helps maintain a certain temperature inside the chimney. This allows for immediate switching to another chimney in case of problems with the waste heat boiler system used for desulfurization and denitration, ensuring that the suction power of the chimney remains unaffected and it can continue to function properly. 2. It generally takes a few seconds for the flue gas shutter to open. In our design, the shutter is interlocked with the fans of the desulfurization and denitrification waste heat recovery system; once there is a power outage in this system or a fault occurs with the fans, the shutter opens automatically, allowing the flue gas to flow out through the chimney. 3. During maintenance of the on-site desulfurization, denitration, and waste heat recovery systems, it is usually necessary to switch to the chimney, as these are two separate systems that do not affect the normal operation of the coke oven. 4. No similar problems have been encountered so far; generally, the distance between the ammonia storage tanks in coking plants and the waste heat boilers is sufficient. 5. Not necessarily. These days, there are many shell companies that only act as general contractors, pooling the resources of various equipment manufacturers without having any own qualifications.

There are few genuine environmental protection companies; large companies outsource such tasks, while smaller companies use fake qualifications to meet the requirements. The safety considerations in these companies are not as good as those in the petrochemical industry

The facility has just installed desulfurization and flue gas treatment systems, and everyone believes that the most dangerous issue is related to suction. Even with fans and waste gas heating in place, it remains quite risky; once the fans stop working, there is no suction at all in the coke ovens, leading to gas leaks everywhere. Later, backup dampers were installed – if the desulfurization and flue gas treatment systems cannot provide sufficient suction, these dampers are activated immediately to use the waste gas for suction. In other words, it’s essential to keep the original flue damper in place as a backup