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Detailed analysis of the cost of cooperative disposal of sol

  In recent years, with the introduction of national environmental protection policies, collaborative solid waste treatment in cement kilns has become the focus of research and application in the industry.

  As early as 2012, the catalogue of advanced applicable technologies for energy conservation and emission reduction in the building materials industry will adopt the technology of pre-decomposition kilns for collaborative treatment of hazardous waste, and adopt pre-decomposition kilns for collaborative treatment of sludge in water plants. Meanwhile, fly ash from waste incinerators will also be included.

  In December 2014, the ministry of industry and information technology, the ministry of science and technology and the ministry of environmental protection jointly issued the catalogue of major environmental protection technology and equipment that the state encourages development (2014 edition) to encourage national development.

  The complete equipment of cement kiln coordinated harmless treatment is included in the promotion project of solid waste treatment equipment.

  In 2015, the ministry of industry and information technology and six other ministries jointly issued a notice on the pilot project of cement kilns to jointly treat household waste.

  Collaborative disposal technology of cement kilns has long been the main treatment method in Germany, Japan and other countries.

  As China is still in the development stage, the coordinated disposal technology of cement kilns is faced with major problems such as high initial investment cost, high operation cost and low government subsidy.

  This thesis cement kiln collaborative treatment of solid waste technology three kinds of coordination in the process, namely the cement kiln collaborative disposal of urban living garbage (RDF), cement kiln collaborative disposal of urban living garbage (joint gasifier) and cement kiln collaborative disposal of urban sewage sludge (dry), based on 5 000 t/d production line, comprehensive consider reduction, cost index, the technology for energy conservation and emissions reduction potential and cost analysis, and technological development policy Suggestions are given.

  1 overview of collaborative disposal of solid waste in cement kilns

  1.1 cement kiln collaborative disposal of municipal solid waste (RDF) technology

  The cement kiln co-disposes the municipal solid waste (RDF) technology, that is, the municipal solid waste is processed into the waste derived fuel (RDF) with higher calorific value and more stable after the pretreatment process of sieving, crushing, fermentation, drying and processing, etc., and the recycling disposal and utilization technology is achieved by combining the combustion characteristics of cement calciner.

  It is suitable for the new dry cement production line collaborative disposal of municipal solid waste technical transformation.

  It should be noted that the distance between waste disposal stations or RDF pretreatment stations and cement manufacturers should not be too far.

  The influence of harmful elements introduced by waste on the normal production of cement kilns.

  F.l.sius' "hot plate" technique and Polysius' pre-combustor technique fall into the umbrella of RDF collaborative processing techniques.

  Domestic huaxin cement and sinoma international have developed such related technologies, and process precombustion technology and equipment are also in the research and development process.

  The cooperative disposal mode of huaxin cement kiln is an innovative mode that integrates the collection and transfer of household garbage, the pretreatment of garbage and the cooperative disposal of cement kiln.

  It is estimated that if the cement clinker production line of 5,000 t/d USES this kind of technology to treat 200~500 t of domestic garbage every day, it can reduce coal consumption of clinker by 3%~6%, increase electricity consumption by 3~5 kWh, reduce CO2 emission of clinker by 4.02~13.23 kg, and reduce NOx emission of clinker by 0.02~0.06 kg.

  The initial investment increased by about 80 million yuan on average, and the operating cost of unit clinker decreased by 3.36~6.72 yuan /t.

  Household garbage subsidy cost is not uniform due to the local government standards (50~200 yuan /t), assuming that each ton of household garbage subsidy 100 yuan, it is estimated that the investment payback period is more than 10 years.

  1.2 cement kiln coordinated disposal of municipal solid waste (combined gasifier) technology

  Cement kiln co-disposes municipal solid waste (combined gasifier) technology, that is, municipal solid waste fermentation, homogenization, crushing, weighing and other processes, first into the gasifier, after vaporization into combustible gas into the cement decomposition furnace incineration, gasifier bottom slag after separation as cement ingredients.

  This technology is a new environmental protection technology which combines the advantages of cement kiln and gasifier, and makes harmless treatment for the waste gas, slag and leachate.

  It is suitable for the new dry cement production line collaborative disposal of municipal solid waste technical transformation.

  It should be noted that: the garbage disposal station and cement production enterprises should not be too far away from each other;

  The influence of harmful elements introduced by waste on the normal production of cement kilns.

  Japan kawasaki, Germany RUDERSDORF cement and other master this kind of technology, anhui conch CKK system technology and nanjing kai maofeng environmental protection gasification incineration system technology and other technologies belong to the scope of this collaborative disposal technology.

  CKK system technology, gasifier single furnace main specifications for 100~400 t/d, supporting 2 000~12 000 t/d and other specifications of cement kiln system.

  According to the investigation, when the amount of garbage feed accounts for less than 10% of cement clinker production, it has no effect on the normal production of cement.

  It is estimated that if the cement clinker production line of 5,000 t/d USES this kind of technology to process 300 t of household garbage every day, it can reduce the coal consumption of clinker by about 4%, increase the electricity consumption by 2~4 kWh, reduce the CO2 emission of clinker by 7.34~8.82 kg, and reduce the NOx emission of clinker by 0.03~0.04 kg.

  The initial investment increased by about 100 million yuan on average, and the unit operation cost decreased by about 4.48 yuan /t.

  Assuming a subsidy of 100 yuan per ton of household garbage, it is estimated that the payback period of investment is about 10 years.

  1.3 cement kiln co-treatment municipal sewage sludge (drying) technology

  Cement kiln co-disposing municipal sewage sludge (drying) technology, that is, municipal sewage sludge into sludge drying system, using waste heat of cement plant to directly or indirectly dry wet sludge (moisture content of about 80%) to dry sludge (moisture content of less than 30%, some drying technology can reach less than 5%).

  Exhaust gas from drying is treated again;

  The obtained dry sludge is in the form of loose particles (partial drying technology can achieve particle size below 10 mm, and the calorific value is up to 12, 540~14, 630 kJ/kg), which can be sent to cement kilns by conveying and feeding equipment, and can be directly involved in combustion as an alternative fuel.

  In addition, dry sludge contains SiO2 and CaO, which can be used as alternative raw materials for cement production.

  The core of sludge drying technology is heat exchanger and dryer.

  Sludge drying system can be divided into calcification thermal drying technology, direct contact drying technology, thermal oil drying technology, sludge fuel technology, etc.

  It is suitable for the new dry cement production line collaborative disposal of municipal sewage sludge technical transformation.

  It should be noted that: the distance between municipal sewage sludge station and cement production enterprises should not be too far;

  Influence of harmful elements on normal production of cement kiln;

  Sealing in the process of municipal sewage sludge transportation;

  Odor monitoring and control problems.

  Japan nihui company and Italy vorone company have mastered the technology of related cement kilns' coordinated disposal of sewage sludge (drying).

  Domestic Beijing cement factory introduces the Italian VOMM high efficiency turbine thin layer drying technology (referred to as turbine thin layer technology/process), which USES heat transfer oil to dry the sludge;

  The swirl nozzle developed by guangzhou yuebao cement co., ltd. is used to directly dry the sludge. It USES the waste heat gas from the kiln tail to dry the wet sludge, and the moisture content of the sludge can be reduced to about 30%[1], which is a typical semi-drying technology.

  Huaxin environmental engineering co., LTD., hefei cement research and design institute and other industrial, academic and research institutions also have corresponding technical application cases.

  The estimate, 5 000 t/d cement clinker production line, sludge 500 ~ 600 t, tons of clinker reduce about 6 kg of standard coal consumption, increase power consumption 3 kWh, reduce the waste heat power generation by about 20%, tons of clinker can realize CO2 emissions by 11.5 kg, the reduction of NOx quantity between 40% ~ 60%, assume that the original tons of clinker NOx emissions of 1.6 kg (the first national pollution source census), NOx reductions of 50%, tons of clinker can realize NOx reduce 0.8 kg.

  The initial investment increased by about 80 million yuan on average, and the unit operating cost of clinker increased by 4.55 yuan /t.

  The cost of sludge subsidy is not uniform due to the local government standards (50~300 yuan /t), assuming a ton of sludge subsidy 100 yuan, it is estimated that the payback period of investment is about 6 years.

  2 potential and cost of synergetic disposal technology for cement kilns

  In order to comprehensively analyze the emission reduction potential and cost of the coordinated disposal of solid waste technology in all major cement kilns, the marginal emission reduction cost curve (MAC) method was used to evaluate and analyze the related technologies with the 5,000 t/d cement clinker production line as the benchmark.

  2.1 marginal emission reduction cost curve

  Marginal emission reduction cost curve (MAC), from the perspective of technology development trend, focuses on the technology emission reduction potential and cost relative to the baseline scenario, and conducts technology evaluation and analysis by ranking the target annual emission reduction cost.

  The main advantage is low data requirements, easy to operate.

  The main analysis steps include:

  1) collect the emission reduction potential and cost of the technology.

  2) collaborative control effect analysis.

  In the two-dimensional coordinate system, the horizontal axis reflects the emission reduction effect of technical measures on NOx, and the vertical axis reflects the emission reduction effect of technical measures on CO2. The spatial position of the technical measures in the coordinate system can directly reflect their emission reduction effect and disposal status.

  3) cost-effectiveness evaluation.

  The cost per unit pollutant emission reduction is a comprehensive consideration of the effect and cost of emission reduction measures, which reflects the cost per unit pollutant emission reduction.

  4) ranking technologies from low to high according to long-term marginal cost, and drawing marginal emission reduction cost curve (see figure 1).

  5) according to the emission reduction target, draw a line through the abscissa (whose value is the target emission reduction), and the left side of the line is the combination of the technologies to be screened.

  Marginal emission reduction cost curve

  2.2 collaborative control effect analysis

  According to China cement yearbook [2] and the first national census of pollution sources [3], NOx emissions of standard coal in cement industry are calculated.

  According to "China cement yearbook" and "China cement industry carbon dioxide emission coefficient calculation data" [4], the cement industry unit standard coal CO2 emissions;

  According to energy data [5], NOx and CO2 emission coefficients of the power industry are obtained.

  Relevant emission parameters are shown in table 1.

  Comparison of solid waste discharge coefficient in cement kiln co-treatment

  According to the basic technical data in part 1 above and the emission coefficient in table 1, the basic data of emission reduction potential and emission reduction cost of the three types of technologies are calculated, as shown in table 2 and table 3, which provides basic data for the subsequent calculation of collaborative control effect analysis.

  The cost of solid waste emission reduction was coordinated by cement kiln

  The weight of each pollutant will be determined on the basis of market transaction price, and the corresponding weight will change with the change of pollutant price, which will in turn affect the numerical value of the coordinated reduction of atmospheric pollutants equivalent APeq, the cost per unit pollutant reduction of technical emission reduction measures and the prioritization results.

  Before the "twelfth five-year plan", NOx was not a total control index, and there was no case of emission right trading. According to the standard management method of emission fee collection, the trading price of NOx was 5,000 yuan /t.

  In 2008, the average price of CDM projects in China's market was about 10~12 euros /tCO2. In this paper, 100 yuan /t was temporarily used as the price parameter of CO2.

  Sensitivity analysis was carried out to investigate the impact of price :(N and C are NOx, CO2 emission reduction potential or emission reduction scenario respectively).

  According to the basic data described in the above sections 1.1~1.3, the NOx and CO2 synergetic control effect two-dimensional coordinate system of the main cement kiln collaborative treatment of solid waste technology is shown in figure 2, and the emission reduction potential of various technical measures and the synergetic emission reduction equivalent index are shown in table 4.

  The three technologies of collaborative disposal of municipal solid waste (RDF) by cement kilns, collaborative disposal of municipal solid waste (combined gasifier) by cement kilns and collaborative disposal of municipal sewage sludge (desiccation) by cement kilns can reduce NOx as well as CO2, with good synergistic control effect.

  From the perspective of the total emission reduction effect, the cement kiln coordinated disposal of municipal sewage sludge (drying) technology has a better total emission reduction effect.

  Cost of solid waste treatment in cement kiln

  2.3 cost-effectiveness evaluation

  The cost reduction results of the technical emission reduction measures for the coordinated disposal of solid waste by major cement kilns are shown in table 5.

  Among the three technologies, the cost of emission reduction of the co-disposal of urban solid waste (RDF) by cement kilns and urban solid waste (combined gasifier) by cement kilns is negative, which has certain economic benefits.

  The cost of synergistic disposal of municipal sewage sludge (desiccation) by cement kiln is positive, and a certain economic cost is needed in the process of synergistic emission reduction.

  2.4 analysis of air pollution and greenhouse gas emission reduction paths in cement industry

  When applied to emission reduction planning, the appropriate emission reduction path can be selected according to the target constraints of "total emission reduction target (that is, the length cut from the origin to the right on the abscissa)" and "marginal cost of emission reduction (that is, the vertical height)".

  According to the principle shown in figure 1, the path of coordinated control emission reduction of solid waste disposal technology in major cement kilns is drawn, as shown in figure 3.

  Cement kiln coordinated price

  As can be seen from figure 3, the first two technologies are obviously located below the horizontal axis, indicating that these two technologies can save costs while reducing emissions, namely, cost-effective emission reduction technologies.

  From the perspective of CO2 emission reduction, NOx emission reduction and synergetic emission reduction equivalent, the cement kiln synergetic treatment of municipal sewage sludge (drying) technology has the greatest potential for emission reduction, which has a good application prospect.

  From the perspective of CO2 emission reduction cost and coordinated emission equivalent cost, cement kiln coordinated disposal of municipal solid waste (RDF) technology has a good investment prospect.

  From the perspective of NOx emission reduction cost, cement kiln coordinated disposal of municipal solid waste (combined gasifier) technology has a good investment prospect.

  From these three aspects, cement kiln system disposal of municipal sewage sludge (drying) technology investment cost is slightly higher.

  Conclusions and Suggestions

  1) it is necessary to give full consideration to the feasibility of NOx emission reduction and CO2 emission reduction synergistic control of solid waste collaborative disposal technology in cement kilns, and it is recommended to give priority to highly collaborative waste disposal technology and give more technical and financial support.

  2) mentioned in this paper, three kinds of cement kiln in collaborative solid waste disposal technology, in addition to cement kiln collaborative disposal of urban sewage sludge (dry) technology, are cost effective disposal technology, but for cement enterprises, a huge financial is a great test of its initial investment, so the necessary subsidies, tax incentives and so on is the most direct and effective means.

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