ACCURATELY DETERMINE THE FORMATION TEMPERATURE, EVAPORATION TEMPERATURE AND PROCESS GAS DEW POINT OF FLUE GAS CONDENSABLES
The Breen Probe measures conductivity across a uniquely constructed probe surface resulting from condensables. The most common condensables seen are sulfuric acid and other sulfur compounds.
SO3/H2SO4 FORMATION IN FLUE GAS STREAMS
All fossil fuels, to some degree, contain sulfur and, when burned at high temperatures, oxidize to SO2 and then to SO3 within the combustion process. The SO3 then combines with water to form H2SO4 (sulfuric acid) within the flue gas. The sulfuric acid may further combine with elements, such as NH3 (Ammonia), and Na (Sodium), to form even more-corrosive condensates.
The following are some negative impacts from sulfuric acid/sulfur condensates:
- Corrosion in ductwork and equipment
- Fouling of equipment, such as tube bundles and air preheaters
- Increased carbon emissions through elevated air heater outlet temperature
- Formation of acid mist in the stack plume
The impacts of such issues are higher operational and maintenance costs, greater equipment wear and tear, increased downtime and reduced efficiencies. Operators, therefore, tend to run their plants at higher flue gas temperatures to prevent condensation and corrosion which has a significant impact on heat rate and efficiency.
DIRECT MEASUREMENT OF SULFURIC ACID VAPOR
The Breen Probe is an industry-proven instrument for measuring the species and levels of the target vapors in utility flue gas streams. It can be placed anywhere downstream of the economizer, from the SCR outlet to the scrubber inlet.
The system works by controlling the boundary layer temperature between the flue gas and the sensor tip of the instrument. Precisely controlled cycling between preset high and low temperatures results in accurate determination of the formation temperature, evaporation temperature and process gas dew point of the flue gas condensables. In the case where the vapor is pure H2SO4 , the system combines this information with gas moisture levels using proven mathematical analysis providing real-time information on SO3 concentration.
BREEN PROBE TECHNOLOGY
The Breen Probe measures conductivity across a uniquely constructed probe surface resulting from condensables. The most common condensables seen are sulfuric acid and other sulfur compounds. The condensables measurement technique and probe designs are described in the United States Patent No. 6,677,765 and 8,256,267 and other foreign patents.
The detection process consists of cooling the initially hot detector surface by controlled application of cooling air. The descent rate is tightly controlled to allow accurate, real-time measurements of condensate conditions on the probe tip. The presence of a condensed liquid phase is determined by current between two electrodes. When current is detected, the kinetic dew point (or formation) temperature has been reached.
Following detection of condensate, the cooling air is decreased and the probe increases in temperature in a controlled manner until the condensate evaporates in order to give a precise measurement of evaporation temperature. After the current is evaporated, the cooling air will stop and allow the probe to go back to its start temperature to begin a new cycle.
The instrument reports a multitude of information variables to the plant control room via 4-20 mA loop, Modbus or OPC link. Examples of reported data, include:
- Formation temperature
- Evaporation temperature
- Dew point
- SO3 concentration
- PID output
- Probe temperature
- Probe current