SCR

Selective Catalyst Reactor (SCR) Sonic Cleaning

SCRs are used to remove NOx in flue gases. Ammonia, which combines with NOx to form water and nitrogen, is added to the gas in the unit. SCR occurs during one or more catalyst blocks through which flue gas must pass.

The decrease in SCR efficiency can cause some problems. For example; Poor distribution of ammonia in SCR, uneven gas velocity in SCR causes contamination in other downstream equipment due to ammonia shift from SCR. Formation of ammonium sulphate and ammonium bisulfate compounds by reaction of ammonia and SO3 can cause contamination. Honeycomb catalysts clog due to particle build-up.

Steam soot blowers usually provide a local cleaning effect close to the installation sites. They do not clean all SCR equipment effectively. With long wavelength SCR soot blowing, the effect reaches everywhere in the SCR elements. Sound pressure reaches all cross sections equally. Continuous cleaning effect (a few minutes pause time), low differential pressure of SCR helps maintain efficiency. Another advantage of the sonic system is; erosion and other harmful effects are prevented.

The installation of a sonic horn in each layer in SCR will keep the formation of contamination on the catalyst to a minimum. In addition, erosion caused by steam soot blowers is not an issue in sonic soot blowers. The low differential pressure and efficiency of SCR are maintained by cleaning with sonic soot blowers. Steam soot blowers are not an effective cleaning system for SCR.

Sonic soot blowers are the most efficient way to maximize SCR efficiency and minimize contamination from design-induced ammonia slip. Thus, SCR efficiency increases. It causes a decrease in the blockage and therefore, it causes a decrease in the congestion caused by ammonia slip.

User Sonic systems enable particles to be set in motion and transported to the appropriate filter and electrostatic system by the gas flow. A partially clogged catalyst layer makes it difficult for gas to pass through the blocks, disrupting the flow. Thus, the efficiency of the unit deteriorates. sonic cleaners replace the soot blowing system in the equipment they are fitted with. They work together with the stream that is present when they installed.

Past installation:

Wansley Power Plant in the USA installed a sonic system in 2001 to keep economizers clean.Sonic cleaning in the power plant has proved out to be a very efficient solution. The power plant decided to install the same type of horns for SCR due to its perfect cleaning results. Keeping it clean with sound is a relatively inexpensive method. It does not damage the structures like steam soot blower. Also the sound reaches every corner. prevents the formation of ash deposits continuously. This situation keeps the differential pressure of SCR at a constant level. It increases the lifetime by 25%. Thus, it reduces the wear on the catalysts. The catalyst from Wansley has 3 layers. 4 sonic horns are installed between the layers.

The size of each layer (16 * 14.3 m).

We use a software model to make sure the sound pressure level (SPL) is adequate over the entire volume. For an effective cleaning with sound, SPL should be at least 135 dB.

This is a very reliable and important tool for determining where to place the sonic horn and what frequency range to choose.

Wansley power plant has 2 separate SCRs. One has classical steam soot blowers, and the other has sonic horns. The diagram from the power plant shows that the differential pressure above 2 twin SCRs is significantly less than when using sonic cleaning. In addition, the sound reaches every corner and does not damage SCR equipment.

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