PYROINC 640BL

Online monitoring in recovery boilers (black liquor boiler)

Task

The combustion of black liquor (energy and lignin-rich by-product in the cellulose production) takes place in the so-called recovery boiler (liquor boiler) and is used to generate electricity and process heat as well as to recover white liquor. In the recovery boiler, heat is used to generate high pressure steam, which in turn is used to generate electricity in combination with a turbine.

Since the high concentration of sulfur requires optimal process conditions, the temperature of the combustion process should ideally be monitored online. A visual assessment of the firing bed (char bed) is also necessary for the optimal process. This is the basis for avoiding the production of sulfur dioxide and other emissions. In addition to the environmentally friendly combustion, a reduction in the inorganic sulfur in the bulk coal must be achieved.

The danger of so-called melt-water explosions must be taken into account. For this reason, the sensors to be used must not be cooled with water.

Solution

The air-cooled infrared furnace camera PYROINC 640BL with flame filter and automatic retraction system and automatic port cleaner unit.

The PYROINC 640BL, which has been specially developed for use in a recovery boiler, works in a spectral range of 3.9 µm, where the main part of the gases occurring in a combustion chamber is transparent. For this reason, the visual imaging is much better than other technology such as TV systems or NIR systems (near infrared).

The measuring temperature range extends from 600 °C to 1450 °C with a resolution of 640×480 pixels. The air-cooled probe has a diameter of 70mm and a length of 906mm or 1526mm. The opening angle is 74 ° x 55 °, which of course is kept free of dirt by a patented air flush. The good temperature resolution of approx. 1.2K @ 600 ° C and a recording frequency of 50Hz enables reliable temperature monitoring. The automatic retraction unit protects the furnace camera in the event of a failure of the cooling air or other malfunctions by automatically extending it from the combustion chamber. With the help of evaluation software, an online image can be displayed for the operator in the control room and temperature values can be transferred to the higher-level process system via optionally available interfaces (WAGO, Profibus, ProfiNet).

This simplifies the control and optimization of the process; In the best case, irregularities can be detected at an early stage in order to initiate countermeasures.

Infrared furnace camera series PYROINC:

The PYROINC are special and extremely robust thermal imaging cameras that are used to measure high temperatures between 750°F and 3270°F (400°C and 1800°C). They have a motorically focusable borescope optics with protective windows. Camera and borescope optics are housed in a water-cooled or air-cooled probe jacket.

The IR radiation inlet has a very small diameter and is air-purged. Thus, the probe cooling jacket can be inserted directly into the combustion chamber through an opening. Together with an automatic retraction unit, it is ensured that the system withstands the high temperatures and special requirements at the site. Depending on the specific application, the cameras measure in different spectral ranges. Different optics and distractions are also available. The 2D infrared sensors used allow for large, continuous temperature ranges. For visualization and further processing of the measured values, the PYROINC are transmitted in real time via Ethernet.