Shandong gas-line monitoring and analysis system

With increased environmental protection efforts, flue gas desulfurization devices not only have, you must also install flue gas desulfurization line monitoring (CEMS) means for CEMS, not a professional, it is difficult to figure out, and its structure, operation principle there varied, in order to make everyone in the choice of CEMS time, detours, I use plain language to explain this thing clear to you spectators reference. ??? First, I want to say is, CEMS system, not a general purpose device, which is talking about, what kind of boiler equipment, what kind of desulfurization equipment, what should install flue gas desulfurization line monitoring (CEMS) device, can not do, "picked up the basket is food" thing. CEMS main test anything? Sulfur dioxide (SO2), nitrogen oxides (NOx), soot and other three things. According to environmental requirements, sulfur dioxide (SO2), soot is will test the project, because most power plants are not denitrator, so nitrogen oxides (NOx) is not required, but in some areas, in order to calculate the nitrogen oxides sewage charges, but also NOx loading apparatus. ?? Flue gas sampling method: non-extraction method and extraction method two kinds. Undecimated + infrared or ultraviolet absorption of such technologies early products abroad in the late 1970s to the early 1980s, its technology is simple, fast response time, do not need real-time measurement of the exhaust pipe can be directly wet basis, the disadvantage is the probe susceptible to clogging dust analyzer easily contaminated; probe of the opening ceremony, was unable to carry out online school standard, accuracy, and later headed the British Procal company improved device, but still not mature, low market share, the very few plants use, so I will not talk about it. I highlight some extraction method, extraction method into direct extraction and dilution extraction method. Direct extraction method is a method of flue gas desulfurization by a device directly extracted from the flue or chimney smoke, the smoke for analysis, the results of SO2 concentrations. Its advantages: European technology to solve the smoke problem disturbances, infrared absorption method on the probe and other equipment is relatively cheap. This technology in Europe, Japan developed better. Disadvantages: the extracted fumes of smoke, dust must, dehumidifiers (sampling tube heating) pretreatment, maintenance complex. Of course, I think the main problem is the measurement of dry flue gas sampling line must be negative run, but in the actual operation of the boiler, it is difficult to guarantee 100% of the negative run, once positive pressure occurs, or sampling tube leaks, smoke will make the sampling tube easy to plug the exhaust port, affect the measurement results. Therefore, in such a direct extraction method of choice when the CEMS, to give full consideration to its own boiler, kind of desulphurization facilities, boiler load and so on, to consider, not blindly choose CEMS. The most common pulverized coal boiler (CFB circulating fluidized bed boiler) + bag dust (electrostatic precipitator) + Limestone - gypsum desulfurization using direct extraction method CEMS, is entirely possible, because bag dust, electrostatic dust more reliable, exhaust fumes the particles can effectively control and use of this technology, are generally large-scale boilers, after a one-time design, design is more negative Kuanyu smoke, unlike some plants after by transformation, an increase of desulphurization facilities, could result in smoke air suction is too small, so that during operation, the flue gas is high probability of occurrence of positive pressure, and prone to sampling tube easy to plug the exhaust port, affecting the accuracy of the measurement. But now there are a lot of small power plants, use of chain boiler (stoker boiler) + alkali desulfurization (used as a desulfurization agent NAOH) + water film dust, such systems, small thermal power, small thermal power plants, or have a large source of waste alkali thermal power plants, more use. Any use of this power plant technology, I think the direct extraction method using CEMS is inappropriate. Because this type of process plant, in operation, water film dust can not be fully guaranteed soot particle emissions, although the country has not been specific about the standard particle emissions, but because of the type of boiler burning coal, the soot particles in the the amount of a very important relationship. In general, the boiler combustion Shanxi, Shaanxi, Inner Mongolia and other regions of coal, more soot particles in the amount, especially burning in the water (over 5%) high in Inner Mongolia coal, steam occupies a large amount of smoke soot particles , although I have no scientific quantitative measurement, but according to the boiler to compare the amount of solid slag, using the Inner Mongolia coal dust soot discharged several times in Shandong, Xuzhou, eastern coal. So much smoke, the probability of entering the sampling exhaust pipe on high. For the power plant, water film dust, the use of CEMS direct extraction method, is very unwise. Because the smoke through water film dust, dust water due to changes in the water film, water film dust on many power plants connected to the water industry water pipe, when the change in industrial water pipe water pressure will cause water film dust into the water After the change, the water changes, the effect of dust will change. In addition, there is good most of the thermal power plant, using a back-pressure machine operation mode, the boiler load varies greatly, especially in a short time when rapid acceleration load, we often see black smoke chimney, flue gas at this time on the huge amount of dust particles, and therefore, some by direct extraction method of CEMS power plants, almost one week we must climb a chimney to clean the probe. And also often appears with data CEMS are not allowed, in particular parameter soot, (mostly gas velocity measurement with Pitot tube) once blocked, will smoke parameters of several thousand, exceeding several times. So direct extraction method CEMS, for small thermal power plants, it is not appropriate. That said for a long time, what type of CEMS used to fit these small power plant. This is - diluted extract + UV fluorescence method. ?? Dilution extraction method is American technology, its advantages are: the flue gas sample taken, adding clean air dilution, this way, it reduces the smoke vapor sample dew point temperature, flue gas condensation problem solved, in general, Needless to trace heated sample line, and solve the problem of corrosion and clogging the sampling probe, continuous long working hours. Sample line can work under positive pressure to prevent leakage due to errors introduced; by the flue gas sample dilution, can reduce the concentration of gas, using a high sensitivity of environmental monitoring equipment to complete the analysis; the humidity is not eliminated from the sample, Determination of wet basis. The disadvantage is: In the detection process, the response time longer (<3min); dry compressed air purity requirements, UV fluorescence analyzer must import more expensive. The technology in the global market share of about 85 percent in the United States up to 90%. So, I think, CEMS diluted extraction method is mature, especially for the harsh environment of smoke, especially small thermal power plants, because of the small capacity boilers to match simple alkali desulfurization, water film dust, etc., the most appropriate . Because the extraction method can dilute the positive pressure operation, sampling is not blocking ash, low maintenance, I passed a lot of visits, using CEMS failure rate of dilution extraction method is far lower than the direct extraction method of CEMS. ?? For the dust measurement, generally with a laser reflection and laser worn. These two methods are mature, stable, high reliability, long service life. Laser reflection method and soot particles color the relevant requirements of coal as stable as possible. This method is generally used, so the boiler when replacing coal, should pay attention to changes in the parameters of the smoke, but we in the actual operation process, no change in coal dust can cause changes in the parameters may also be little change, not easy to see. Laser worn good correlation with the gravimetric method, stable, sensitive, high precision, the devices are small, glossy little maintenance. This method is also a lot of domestic equipment, in any case, these two methods, equally matched, in a word, is good! ? Continuous measurement technology flue gas velocity, generally there are pitot law, which is commonly used method of continuously measuring flue gas velocity ,, disadvantage is easy to block, the need to constantly purge. Another method is the ultrasonic method, the method independent of temperature, pressure, flue gas composition change impacts, but the product more expensive. Most domestic continuous measurement of flue gas flow rate using a pitot tube method. ? In selecting CEMS time, money plant, all imported equipment, that the equipment imported quality assurance, a typical "just vote for you, do not choose the right." Can be used on imported equipment, of course, it is a good thing, but to choose their own to match the CEMS, otherwise they will be sometime in. Similarly, saving power plant, through bidding, do everything possible to keep the prices down, bought a cheapest, with a one year parts and other testing probe is broken, replace one, the cost is not small. So, when we purchase CEMS, one should remedy the election right; the second depends on the CEMS manufacturers, whether intellectual property rights, there are a lot of small companies in the community, relying on the relationship between the EPA, the CEMS assembled, once found quality problems, since they do not have independent intellectual property rights, equipment breaks down, unable to make repairs yourself, you can replace parts, plus service can not keep up, there are a lot of plants eaten this loss. CEMS receive future municipalities, provinces and other environmental authorities collect fumes sewage charges to be levied according to CEMS upload data, so, CEMS running stability, enough to pay off the costs play a crucial role, not sloppy . ?? CEMS choice, according to their own situation, can not be "picked up the basket is food," "pulling cattle is a horse", or to suffer.