On June 13, the "11th China Cement Energy Conservation and Environmental Protection Technology Exchange Conference-Equipment Renewal Forum" was held grandly. Wu Shangan, Senior Consultant of China Cement Network, Professor-level Senior Engineer of Hefei Academy and Secretary-General of the former Bag Committee, made a keynote report on "Ultra-low Emission Technology Transformation and Equipment Renewal for Air Pollution Control in Cement Industry". This paper discusses how to evaluate the progress of air pollution control technology in cement industry, the technical transformation and equipment renewal of ultra-low emission air pollution control in cement industry, the work plan of investigation and remediation of inefficient and ineffective air pollution control facilities, the technical transformation of ultra-low emission air pollution control projects in cement industry, and the intelligent operation and maintenance management of air pollution control facilities in cement industry.
First, the cement industry's ultra-low emission technology transformation and equipment renewal
, the cement industry's environmental protection pressure is not small. In January, the Ministry of Ecology and Environment issued the Opinions on Promoting the Implementation of the Cement Industry's Ultra-low Emission. 50% cement < a href = "https://price.ccement.com/Price_list-1-s0-e0-p0-c0-k100059-b0. the national cement enterprises should implement the ultra-low emission requirements: the whole process of the cement industry particulate matter, sulfur dioxide, The emission concentration of nitrogen oxides is not higher than 10, 35 and 50 mg/Nm3 respectively.
At present, the cement industry has a serious overcapacity, the efficiency of the whole industry is declining sharply, and there is basically no benefit. At this stage, it is suggested that the existing pollution control facilities should be transformed rather than completely "updated". In November
last year, the Ministry of Ecology and Environment formulated the Work Program for the Investigation and Renovation of Inefficient and Ineffective Air Pollution Control Facilities, which clearly States that the comprehensive investigation of air pollution control facilities in iron and steel, cement, coking and other industrial furnace and kiln industries; Establish a list of investigation and rectification, "eliminate a batch, rectify a batch, and upgrade a batch"; eliminate the treatment processes that are immature, inapplicable, and unable to meet the emission standards steadily.
By the end of this year, the whole country will complete the investigation work, including: 1. Applicability of treatment process; 2. Material balance calculation; 3. Inspection of pollution control facilities; 4. Inspection of automatic control system and production account; 5. Inspection of unorganized and abnormal emission conditions; 6. Automatic monitoring inspection; 7. Manual monitoring inspection; 8.
Requirements for investigation and remediation of pollution control facilities in cement industry:
1. Requirements for investigation and remediation of operation and maintenance of dust removal facilities, focusing on the matching of emission concentration, resistance of dust removal system, ash accumulation, replacement of filter bags, differential pressure of filter bags, filter wind speed, fan power, ash unloading mode, etc. With the operation and maintenance specifications of dust removal facilities;
2. Requirements for investigation and rectification of denitrification process and equipment. The investigation focuses on the flue gas emission characteristics and denitrification process of the enterprise. Verify whether the denitrification process adopted matches the emission characteristics and whether it is consistent with the information specified in the pollutant discharge permit. Check the pipeline corrosion of denitration equipment and the configuration of key parameter meters such as flow, temperature and pressure difference of denitration agent, and make sure that the ammonia escape is not higher than 8 mg/Nm3.
3. Similar to the out-of-stock requirements, the desulfurization process and requirements are clearly defined
. 3. Technical transformation
of ultra-low emission engineering for air pollution control in cement industry The main pollutants in cement industry are particulate matter, NOx and SOx; The ultra-low emission of cement industry means that the organized and unorganized emission of air pollutants in all production links (crushing, grinding, batching, clinker calcination, drying, co-disposal, etc., as well as the storage and transportation of raw materials, fuels and products) and the transportation process should meet the ultra-low emission requirements.
(1) Ultra-low emission control project
of particulate matter in cement industry At present, the technology of particulate matter pollution control in cement industry, that is, dust removal, is very mature, but some enterprises built in the early stage, some kiln heads and kiln tails are still using electrostatic precipitator, and there is no transformation in the later stage, so it is very difficult for electrostatic precipitator to achieve ultra-low emission of particulate matter; In order to save investment in the construction process, some enterprises adopt some low-efficiency bag filters and are not in place in the operation and maintenance process, including the purchase of accessories not according to the technical requirements, especially the purchase of accessories at a low price, which results in the failure of particulate matter to meet the ultra-low emission requirements. For the technical transformation of these projects, there are the following suggestions:
1. The technical scheme of electric bag:
Scheme 1: use the box of the original electrostatic precipitator to transform the original electrostatic precipitator into a bag filter;
Scheme 2: update the equipment, remove the original electrostatic precipitator, and replace the original electrostatic precipitator with a brand new bag-type precipitator;
Scheme 3: retain the first electric field of the original electrostatic precipitator, and combine it with the "electric-bag composite precipitator" in the rear electric field. Successful case of
electric bag transformation: the cement kiln tail dust collector of Huaining Shangfeng 5000t/d production line transformed by Hefei Institute last year transformed the electrostatic precipitator box into bag chamber, added platform, railing, gas circuit system and electrical control system, and adopted the high-flux glass fiber membrane filter bag of Anhui Jixi Hualin Glass Fiber Filter Material Company.
4. Unorganized emission control measures
Material storage, material transportation, production process and other unorganized emission sources, on the premise of ensuring safe production, adopt effective control facilities such as sealing. The unorganized emission control facilities and production facilities operate normally synchronously, there is no visible smoke and dust escaping from the dust-producing points and production facilities, and the plant area is clean and clean without dust accumulation.
5. On-line monitoring
cement enterprises must check whether the principle selection of on-line monitoring equipment equipped by the environmental protection department is reasonable, whether it is calibrated according to the requirements, whether it can provide commissioning and testing reports and technical acceptance reports that meet the requirements of standards, and set relevant parameters according to the commissioning and testing results.
(2) NOx ultra-low emission control project
in cement industry is the difficulty of air pollution control in cement industry, and it is also the largest investment. Cement enterprises should scientifically use efficient and appropriate denitrification processes according to the characteristics of production process flue gas, and eliminate inefficient denitrification technologies such as simple dust removal, desulfurization and denitrification integration, microbial denitrification, direct spraying of denitrification agent in the flue, as well as treatment technologies with unknown treatment mechanism and unable to remove pollutants through denitrification agent or by-products. Ammonia handling, storage, transportation, preparation and other processes shall be sealed, and ammonia leakage detection measures shall be taken.
For SCR denitration, the resistance of single-layer catalyst should not be higher than 300 Pa, and the catalyst performance should meet the relevant technical requirements.
In recent years, the cement industry has also developed many kinds of SCR out-of-stock process routes. In order to meet the ultra-low emission requirements, the technical route should be selected scientifically and reasonably. From the SCR technical route that has been put into operation, the operation reliability of the "high temperature and low dust" technical route is higher. It has the following advantages:
1. Vanadium-titanium catalyst is a classic and mature catalyst, which has good catalytic effect within the temperature window;
2. The amount of catalyst is small, which is reduced by 1/2 compared with other methods;
3. Low dust solves the problems of catalyst wear and poisoning; The ammonia consumption of the
4、 is greatly reduced, the problem of ammonia escape is solved, and the ammonia consumption is less than 3.
Other SCR denitrification process routes still need time to verify.
Taking China Resources Cement Changzhi 5000t/d Project as an example, actual operating parameters:
standard flue gas volume: 380000Nm ³/H;
flue gas temperature: 310 ℃;
inlet dust concentration: 100g/Nm ³;
Inlet NOx concentration: 500mg/Nm ³;
outlet dust concentration: < 10mg/Nm ³;
outlet NOx concentration: < 30mg/Nm ³;
Ammonia escape: < 2.
(III) Cement industry SOx ultra-low emission treatment project
Sulfur oxides in the cement industry are mainly produced during the combustion and decomposition of fuels and other substances. The ultra-low emission requires that the SOx in the cement kiln should be controlled within 35mg/Nm3. It is necessary to increase tail gas treatment facilities, and the existing mainstream technology is wet limestone-gypsum method. It is required by environmental protection that waste liquid, waste residue or byproducts shall be discharged in wet desulphurization. The pH value of the slurry after the reaction of lime/limestone-gypsum, ammonia method and magnesium method shall be weakly acidic, and the slurry after the reaction of sodium alkali method and double alkali method shall be alkaline. It is forbidden to mix desulfurization by-products into fuels and raw materials for combustion, or to discharge them directly with wastewater without treatment.
Four、 Intelligent operation and maintenance
of air pollutant treatment in cement industry < IMG SRC = "https://img7.ccement.com/richtext/img/fbwwid5k2tb1718871886978.
The cement industry is currently experiencing unprecedented economic and talent difficulties;"; Environmental protection is the red line for the survival of cement enterprises. Cement enterprises that are expected to survive in the future should have long-term development plans, scientifically and reasonably choose ultra-low emission technology routes that can operate stably, have mature technology, convenient management, low operation cost, no secondary pollution, and should also consider convenient start-up and shutdown and energy saving at present. Especially for the selection of out-of-stock technical route, long-term and reliable operation must be the first choice.
