Shao Mingzhu: Practice and Thinking of Ultra-clean Emission of Cement Production Line

In the current environment of building ecological civilization, the cement industry must adhere to the green development strategy, unswervingly take the road of ecological priority and green low-carbon, and enterprises should accelerate the transformation to resource-saving and environment-friendly enterprises. In recent years, through continuous technological transformation and innovation and upgrading, the main production indicators of Sinoma Zhuzhou Cement Co., Ltd. have reached the advanced level of the industry, and the NOx and dust emission data have reached the ultra-low emission requirements, effectively practicing the green development path.

Sinoma Zhuzhou Cement Co., Ltd. was established in October 2005 with a registered capital of 230 million yuan and total assets of 840 million yuan. It is a new

Dust Ultra Low Emissions

in Dust Ultra Low Emissions " On the other hand, Sinoma Zhuzhou has taken three major measures , namely, maintenance, technical transformation and routine inspection.

Overhaul and maintenance means that the inspection of the dust collector is included in the overhaul plan, and the dust collector of the production system must be thoroughly checked for each overhaul. Dust collector inspection covers filter belt, air duct, air chamber, injection pipe, valve, air pipe and other parts; fluorescence test shall be carried out regularly for large dust collector to check and fill gaps. The

technical transformation mainly includes the electric bag composite transformation of kiln head dust collector, the transformation of kiln tail dust collector, the transformation of coal mill and cement mill dust collector, and the ultra-low emission transformation of small dust collector.

Firstly, in the transformation of the kiln-head dust collector and the electric-bag composite dust collector, the kiln-head dust collector is changed from a 4-electric field electric dust collector to an electric-bag composite dust collector, and only one electric field is reserved; a water spray cooling valve and a cold air valve are added to ensure that the inlet temperature of the dust collector is controlled within 150 deg C, so as to avoid the damage of the filter belt caused by high temperature; A new type of gas distribution plate was added to evenly distribute the flue gas and improve the dust collection efficiency. After the transformation of the dust collector system, the resistance increased by about 1 000 Pa, and the head exhaust fan was transformed accordingly.

Secondly, in the transformation of kiln inlet dust collector, the bag chamber of dust collector is increased by 1500 mm, the filter belt is lengthened, the filter area is increased, and the filter wind speed is controlled at 0.

Thirdly, in the transformation of coal mill and cement mill dust collector, the overall height of dust collector box is increased by 1500 mm, the filter belt is lengthened, and the filter area is increased. The filtering wind speed is controlled at 0.

Fourthly, in the ultra-low emission transformation of the small dust collector, the single pulse dust collector is completely replaced by the air box pulse dust collector, so as to avoid the secondary flying of dust caused by blowing dust removal and effectively improve the dust removal effect; The filter belt is lengthened, the filter area is increased, and the filter wind speed is controlled at 0.

In daily inspection , Sinoma Zhuzhou applies the dust collector equipped with rapping motor and material level detection device to strengthen the three-level inspection of the dust collector and comprehensively improve the quality of the dust collector inspection; The working pressure of the pulse valve, ash cleaning cycle, compressed air quality, air leakage and air leakage are listed in the inspection list to ensure the normal and stable operation of the dust collector; all dust collectors are equipped with material level meters and rapping motors, and the central control pays attention to the accumulation of materials in the dust hopper in real time.

In terms of ultra-low emission of NOx, the first is accurate out-of-stock, the second is process optimization, and the third is the use of SCR technology.

Precise denitration is mainly to use fluid dynamics simulation software to model the pre-decomposition system and find the best temperature window for NOx reaction; Secondly, the position of ammonia spray gun was adjusted, eight spray guns were arranged at the cone of C5 cyclone, six spray guns were arranged at the outlet of C5 cyclone, and one spray gun was arranged on each side of the gooseneck of the decomposition furnace. Finally, the amount of ammonia sprayed was accurately measured by intelligent technology to ensure the precise injection of ammonia and effectively improve the denitrification efficiency.

After the transformation of staged combustion, the consumption of ammonia water for denitrification is reduced by about 50%. After the transformation, because it is difficult to accurately control the proportion of coal and material distribution, and in order to ensure the reducing atmosphere, the air consumption of the system needs to be reduced appropriately, which leads to the increase of the fluctuation sensitivity of the system and greatly increases the difficulty of operation. After the transformation, although the amount of denitrification ammonia water is greatly reduced, the stability of the kiln condition is poor, which leads to the obvious decline of the clinker quality, the qualified rate of free calcium and the clinker strength.

applied to cement enterprises mainly include high temperature and high dust and high temperature and medium dust." However, it is difficult to fundamentally solve the risk of catalyst poisoning, blockage and wear caused by high temperature dust, and the forced "bypass" caused by catalyst blockage occurs from time to time.

In order to eliminate the operation risks caused by catalyst poisoning, blockage and abrasion in the high temperature and high dust and high temperature and medium dust schemes, Sinoma Zhuzhou and Henan Sinoma Environmental Protection initiated the one-box SCR denitrification technology scheme (high temperature and low dust). The technology consists of a high-temperature dust removal system, an SCR denitration system, a flue system, a compressed air system and a control system. Relying on the core technology of high temperature metal filter bag (high temperature resistance, corrosion resistance, high strength and good wear resistance), the process flow is that the high temperature dusty flue gas from the C1 outlet is first filtered by the high temperature metal filter bag, the dust concentration of the flue gas is reduced to less than 10mg/Nm3, and the filtered high temperature clean flue gas enters the SCR denitrification area for denitrification. Finally, the waste heat is comprehensively utilized. According to the detection of

professional organization, the SCR system has been operated for more than one year without bypass caused by catalyst blockage; NOx emission concentration is less than 50mg/Nm3; ammonia escape is less than 2.5mg/Nm3; system pressure loss is less than 1050Pa; system temperature drop is less than 5 ℃; total NOx emission is reduced by about 540 tons/a; The consumption of ammonia water for denitration is about 0.

Shao Mingzhu concluded that the key for dust collector to achieve ultra-low dust emission is to reduce the filtration wind speed and improve the dust removal efficiency; the ammonia water spray gun is usually arranged at the cone of C5 cyclone for precise denitration technology, which is easy to cause skinning of the spray gun and the risk of blocking the feeding pipe; Staged combustion technology can effectively reduce NOx emissions, but it affects the stability of kiln conditions and is easy to cause ". Sinoma Zhuzhou has made great achievements, including ultra-low emission of dust and NOx; the total amount of dust emission has been reduced by about 23 tons; the total amount of NOx emission has been reduced by about 540 tons; the enterprise has been listed as a national green factory; The mine was listed as a national green mine and P. O 42.

In addition, Shao Mingzhu also put forward seven thoughts on the ultra-low emission of cement production line.

Firstly, the key for the dust collector to realize ultra-low dust emission is to reduce the filtering wind speed and improve the dust removal efficiency;

secondly, the internal anticorrosion treatment of the dust collector can prevent the problem of excessive emission caused by the corrosion of the air chamber and the air duct;

Third, the ash hopper of the dust collector is equipped with a level gauge and a rapping device to avoid the collapse accident of the ash hopper caused by the accumulation of materials in the ash hopper;

fourth, the ammonia spray gun is usually arranged at the cone of the C5 cyclone in the precise denitration technology, which is easy to cause the scaling of the spray gun and the risk of blocking the discharge pipe;

Fifthly, the staged combustion technology can effectively reduce the NOx emission, but has an impact on the stability of the kiln condition and is easy to cause the fluctuation of the clinker quality;

sixthly, the SCR technology is the best technical scheme for realizing the ultra-low NOx emission and effectively controlling the ammonia escape amount at present;

Seventh, the SCR denitration technology (high temperature and low dust) can effectively solve the problem of catalyst blockage.