author: anonymous
the current energy-saving emission reduction of cement industry mainly comes from two aspects. the domestic cement industry, a huge volume, built in 2016 production reached 24.03 tons, the resource consumption and pollutant emissions greatly; secondly, the cement industry is facing serious overcapacity problem, according to the "state council no. 34" the policy requirements, energy saving and environmental protection index will become an important means of elimination of excess capacity.
according to earlier this year announced the "13th five-year" energy-saving emission reduction targets, by 2020, the national yuan gdp energy consumption decreased by 15% compared to 2015, the total energy control in less than 50 tons of standard coal. the national emissions, chemical oxygen demand, ammonia, sulfur dioxide, nitrogen oxide emissions were controlled at 20 million 10 thousand tons, 2 million 70 thousand tons, 15 million 800 thousand tons, less than 15 million 740 thousand tons, down 10%, 10%, 15% and 15% respectively than in 2015.
also, according to the planning of green industrial development ministry released last july "(2016-2020)", by 2020, the comprehensive energy consumption of cement clinker to 2015 from 112kg to 105kg.
the pressure of energy saving and emission reduction current cement industry mainly from two aspects. the domestic cement industry, a huge volume, built in 2016 production reached 24.03 tons, the resource consumption and pollutant emissions greatly; secondly, the cement industry is facing serious overcapacity problem, according to the "state council no. 34" the policy requirements, energy saving and environmental protection index will become an important means of elimination of excess capacity.
on energy saving and emission reduction of cement industry in recent years has been of concern for the industry, to achieve the goal of energy saving and emission reduction, industry and policy aspects have put forward many measures, but not all measures can play a fundamental role.
two misunderstandings of energy saving and emission reduction in cement industry
myth: cancel low grade cement to the cement industry green development
to ease the pressure of excess capacity in recent years, the voice can be heard without end to cancel the p.c32.5 cement. according to december 2014 issued by gb175-2007 "general portland cement" national standard no. second amendment, from december 1, 2015, cancel 32.5 composite portland cement.
now more than a year has passed, even if p.c32.5 grade cement has been replaced by p.c32.5r grade cement, but the domestic to cancel p.c32.5 cement controversy still did not stop, especially after the recent industry came to fully cancel 32.5 grade cement, opposition more than ever.
some industry called for the cancellation of the 32.5 concrete intention is not difficult to understand. on the one hand, it is considered that high mark cement is beneficial to improve the strength of concrete and improve the quality of construction; on the other hand, the removal of low grade cement can increase the amount of clinker and relieve the pressure of excess production capacity.
however, these assumptions can not be achieved. first, the performance of concrete affected by many factors, the cement is on the one hand, and the high strength concrete is not equal to high performance concrete; second, after all is clinker cement overcapacity overcapacity, if not limit the clinker production, whether it is to resolve the overcapacity and energy saving and emission reduction are extremely difficult.
canceled 32.5 grade cement cement for energy saving and emission reduction is not necessarily beneficial. first of all, cement production is the main force to digest various industrial waste residue, and it takes on more than 70% of the domestic waste residue comprehensive utilization. among the various cement varieties, 32.5 cement is the most capable of digesting industrial waste residue. the abolition of 32.5 grade cement will have a serious impact on the digestion and treatment of industrial waste residue. secondly, cement as a semi-finished products, the ultimate aim is to serve the concrete industry, after the cancellation of 32.5 grade cement concrete, preparation process, mixing station to add the admixture may increase, due to grinding mixing control technology than cement enterprises, could lead to the construction quality decline, affect the service life of buildings, for the society is undoubtedly a great waste of resources.
in fact, in order to promote the green development of cement industry, the amount of clinker will be reduced internationally.
according to media reports, the end of last year the cement standard en197-1 then added two new low clinker content cement. in addition, as early as 2011, some cement research institutions in germany put forward that the clinker content of portland cement could be reduced to 50%, and a continuous experimental study was carried out.
report pointed out that the cement industry is facing tremendous pressure to save high-quality fossil fuels and reducing co2 emission. in the absence of a new cementing material which can completely replace portland cement, the development of low clinker and multi component cement is undoubtedly an important energy saving and emission reduction measures.
in addition, level of cement strength and concrete performance does not exist necessarily linked. concrete prepared by many factors, such as aggregate gradation and particle type, mineral admixture, admixture, construction and maintenance and so on, the use of high strength cement may not only enhance the performance of concrete, and even lead to concrete cracking phenomenon.
famous concrete expert professor lian huizhen of tsinghua university has pointed out that in the eyes of some people, the strength of the cement is higher, the more the better, in fact the quality of concrete, high performance concrete is true with the least amount of cement prepared by the most suitable requirements of concrete construction.
the current cement industry has claimed that because the amount of cement clinker production more than a ton of domestic and international level, so we should increase the dosage of clinker. and no matter whether the cement produced by a ton of cement in the world is lower than that in china, even so, the data is not comparable.
on the one hand, the domestic and foreign market of different cement, low grade cement has more application space; on the other hand, clinker production not to increase or decrease the yield strength of cement clinker, but the use of reasonable production to ensure the quality of construction should not be confused in the causal relationship. to meet the actual construction requirements, less clinker prepared more cement, in fact, is a good thing to reduce resource consumption, and nothing wrong.
misunderstanding two: staggering production can play the role of energy conservation
cement industry peak the earliest production was put forward in 2014 npc and cppcc, that is to alleviate air pollution in winter and cement overcapacity. after several years of promotion, to 2016-2017 years, the cement industry in winter peak production scale and time has created the highest record in history.
according to statistics, chinese cement net 2016-2017, in addition to the fifteen northern province, hubei and hunan, sichuan, chongqing, jiangsu also joined the ranks of staggering production, plus fujian, guangdong, guangxi, zhejiang and other southern provinces in winter to stop the kiln, the winter round staggering production covering the major areas of domestic cement production.
staggering production is a large-scale promotion, one important reason is that some industry insiders believe that this policy is conducive to energy saving and emission reduction of cement industry, and to alleviate the problem of overcapacity.
get from the april 2015 meeting of the "2015-2016 years of staggering cement production forum data. allegedly "implement load shifting production of seven provinces and one district two, effectively reduce the cement clinker production capacity yajian, clinker production capacity of 85 million 560 thousand tons; staggering cement production pilot areas a total reduction of 10 million 750 thousand tons of coal consumption, reduce carbon dioxide emissions 63 million 300 thousand tons, 92 thousand tons of nitrogen oxide emissions reduction, reducing dust emissions 33 thousand tons."
however, the author believes that the data is not accurate, perhaps before the data, coupled with the concentration of emissions is more appropriate. cement as a rigid demand product, and no alternatives, the annual output reflects the actual demand for the whole year. in short, the annual output of cement is not constrained by human factors.
winter staggering although production can reduce pollutant emissions and limit the concentration of winter winter clinker production capacity to play, but the real effect of cement production is the demand, there is no alternative in the context of the product, the annual amount of cement production, even in winter to reduce production, also cannot change the annual output. since output can not be transferred by human will, there will be no way to reduce the total amount of pollutants discharged in the whole year.
in addition, due to staggering production, stop the kiln kiln cement enterprises throughout the year the number is relatively increased, it will bring more resources and energy waste.
energy-saving emission reduction cement industry direction is very clear
cement industrial base of china is vast, only the year 2016 reached 24.03 tons of cement production. therefore, even if the environmental standards have been basically achieved, and the international standards, but the total amount of pollutant emissions is still enormous, similarly, energy and resource consumption is astronomical.
in addition, according to experts predict that in the economic transition, the future of domestic cement demand will still be as high as 18 tons, the domestic energy-saving emission reduction of cement industry is a long-term and arduous task. then, cement industry should be how to promote energy-saving emission reduction?
1. the upgrading of technical equipment
as early as a few years ago, chinese building materials federation proposed the concept of "the two generation of new dry cement". the 8 technology requirements in line with the development trend of modern cement industry: 1, high efficiency and low nitrogen preheating decomposition and firing technology; 2 bed grinding technology and high efficient energy saving material; 3, raw materials, fuel allocation technology; 4, digital intelligent control technology; 5, waste harmless disposal and resource the use of technology; 6, a new low carbon high grade cement clinker production technology; 7, high performance and high efficiency filter bag dust reduction technology; 8, high performance non-toxic nitrogen oxide catalyst technology.
specific technical and economic data indicators: (1) the specific heat consumption of clinker can be <2680kj/kg.cl (640kcal/kg.cl); (2) than the cement comprehensive power consumption (po42.5); <75kwh/t (3) alternative fuel rate >40%; (4) the new cement clinker than co2 emissions decreased by 25%; (5) the main production the equipment of dust emissions of <20mg/nm3; (6) labor productivity increased by 1.5-2 times; (7) production line capacity production line of 5000t/d 60-80; (8) can be 30% lower than the cost of management; (9) can reduce the production cost than 15%-20%.
"the two generation of new dry cement" covering the basic aspects of the development of modern cement equipment technology. at present, the technical indicators are extremely advanced, reaching the world's leading level. at present, the overall progress of research and development has reached more than 70%. the "two generation of new dry cement" put forward also proved that the current domestic cement technology and equipment upgrade space is still great.
in fact, in recent years due to the decline in market demand, increased competition among enterprises, in order to reduce production costs, cement enterprises also strengthen the pace of transformation of production line equipment manufacturing enterprises, corresponding also introduced a number of new technology. small to every typhoon machine, motor transformation, large to the burning system optimization and enterprise information management system upgrade, the application of new technologies for cement enterprises have brought tangible benefits.
a study of the domestic cement enterprises, integrated the most advanced raw material measure system, online analysis, automatic control system of production line optimization expert system, the production site of unattended system and internet remote terminal control system technology, to create a new dry cement industry of china's first world-class intelligent production and low energy consumption cement the line, tons of clinker coal consumption is lower than 100kg, with hundreds of workers within the total production index.
overall, the process of cement production line is very complex, from all aspects of the technology upgrade to the optimization of production line based on, there are still enormous development potential. with the "intelligent manufacturing" concept put forward, intelligent production control technology will become the standard of the cement industry in the future, then, the cement industry energy saving and emission reduction is expected to reach new heights.
2. the search for alternative energy sources
cement production requires a lot of energy, in 2016 the domestic only 1.9 tons of coal consumption of clinker burning achievements.
mainly rely on coal china cement clinker burning coal, but it is not the only choice. in foreign countries, especially the european union, in order to reduce the consumption of fossil fuels in cement production, it has long ago begun to seek alternative energy sources, which is very important for the collaborative disposal of waste.
data show that about 28% to 2009 at the end of the european cement industry all the heat demand the use of alternative material right, some eu members have reached more than 60% of the rate of substitution. the current situation in the european cement industry has reached an annual level of about 6 million 600 thousand metric tons of coal. through these, the demand for non renewable resources has been greatly reduced.
cement factory has a lot of energy including: alternative, animal carcasses, animal fats and unclean animal feed; waste oil; waste tire; pretreatment of industrial garbage and waste water treatment plant; sludge; paint factory, paint factory waste; wood, furniture, household electrical appliances factory waste industrial sludge and so on.
to lafarge group as an example, when an outbreak of mad cow disease in europe, a lot of cow carcasses need timely treatment, lafarge group took this "work", the carcasses are used for the production of cement fuel. this helped the government deal with the waste and received tens of millions of euros in government subsidies and saved energy for businesses. moreover, if the use of waste tires as an alternative energy, it contains iron, but also can improve the quality of cement.
specific to our country, the annual output of living garbage, waste oil, waste tires and sludge and other cement can be used to replace energy waste is equally huge. taking sludge as an example, data show that the amount of sludge produced in china has reached about 70 million tons, of which municipal sludge and industrial sludge account for half respectively (water content is about 80%).
overall, the cement industry production in china is not the lack of alternative energy, but the lack of relevant laws and regulations support. domestic cement kiln collaborative disposal is not too late, as early as the beginning of this century has been applied in some domestic cement enterprises, but really from the national level to support and large-scale promotion, only in recent years.
laws and regulations and the key technical indicators and lack of management consciousness for domestic garbage disposal in cement kilns to cause no small difficulty. however, based on the successful experiences abroad and the non renewable nature of fossil fuels, it will be a general trend to use more alternative energy sources for cement production in the future.
3. reduce the dosage of clinker
clinker production is the main energy consuming part of the cement industry, thus reducing the consumption of clinker is the most direct means of energy saving and emission reduction. in fact, for the needs of energy saving and emission reduction, the eu has already been able to reduce the clinker content in cement as the important direction of cement product development without affecting the concrete performance.
can reduce the dosage of clinker, at present there are two main paths. first, research and development of low clinker cement new varieties, such as two low cement clinker content at the end of last year, the eu new cement standard en197-1; secondly, through optimizing the preparation link of concrete, reduce the amount of cement clinker.
single properties of cement based products, the first path is to expand the space is limited, mainly based on different characteristics to improve the performance of low clinker cement admixture. for example, to improve the compactness of the late strength of cement and concrete with ground granulated blast furnace slag; mixed with ground limestone powder to improve the early strength of cement concrete, to prevent bleeding and so on.
the second article is, in part, the continuation of the first. cement is always an industrial semi-finished product, and ultimately needs to serve the concrete production. the amount of cement in concrete directly determines the cement production, but the factors affecting the performance of concrete is not only include cement, aggregate gradation, grain type, the use of additives, mineral material application and maintenance system etc..
therefore, through the optimization of other aspects to improve the performance of concrete, and reduce the dosage of cement become feasible countermeasures.
in fact, based on the current research of application technology, and maintenance of concrete preparation has a lot of technical support. according to tsinghua university professor lian huizhen's introduction, through the optimization of mixing technology, the use of 32.5 cement concrete c60 above the configuration has become possible.
needs to be pointed out that the cement plays a major role in the adhesion strength of concrete, but not all concrete requirements are high strength, according to the actual needs of the situation, the allocation of different types of concrete, which is also for many years the industry has been mentioned, what is the high performance concrete. the author believes that the most suitable for concrete construction needs of concrete is high-performance concrete.
then, what is the real energy saving and emission reduction of cement industry? meet the demand of building construction with the least energy and resource consumption.
article source: http://www.ccement.com/
