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Shree Cement has eight cement plants in Rajasthan and one grinding unit in Uttrakhand. This results in having an aggregate capacity of 13.5 million tonne per annum. It has plants at Beawar, Ras, Khushkhera, Jobner (Jaipur) and Suratgarh in Rajasthan, Aurangabad in Bihar and more.
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Cement plant is necessary for cement production, mainly consist of a series of cement equipment apply for preparation of cement raw materials, clinker production, and finished cement production, such as cement mill, cement crusher, rotary kiln, cement roller press, cement dryer, clinker cooler, cement silo, and related cement plant equipment. AGICO CEMENT is a cement plant manufacturer who owns ability to manufacture cement equipment and provide EPC turnkey project for cement plant.
AGICO Cement is a cement plant manufacturer with production capacity of 30,000 tons of equipments and structure parts and 20,000 tons of casting parts.own production equipment of 8m Vertical Lathe, 10m gear rolling machine, 8m Gantry milling machine, 200mm floor-type boring and milling machine,1203200mm bending machine, 150t crane and 40t electric furnace.
The evaluated cement plants with carbon capture based on reactive gas-liquid and gas-solid systems were modeled and simulated using ChemCAD software package. The developed models for CO2 capture were validated by comparison to the experimental / industrial data. A cement plant without carbon capture was considered as a benchmark case but it was not modelled, the main techno-economic and environmental indicators for the benchmark case were based on key references in the field (IEA-GHG, 2008).
The mass and energy balances for the cement plant concepts with carbon capture were used furthermore to evaluate the key plant performances. The designs were optimized by performing a heat integration analysis (using pinch technique) for maximization of the overall energy efficiency (Smith, 2005). As an illustrative example, Figure1 presents the hot and cold composite curves for the calcium looping cycle (Case 3).
In both investigated cases, an additional coal-based combined heat and power (CHP) unit is required to cover the ancillary energy consumption of the cement plant with carbon capture. As main energy consumptions of the carbon capture designs one can mention: thermal regeneration of the chemical solvent (Case 2) and calcium-based sorbent (Case 3) as well as CO2 conditioning (drying and compressing). The main technical and environmental indicators of the two investigated carbon capture technologies to be used in conjunction with a cement plant are presented in Table2.
As can be noticed from Table2, both cases have a small surplus of electricity (after ancillary plant consumptions were covered) to be sent to the grid. The carbon capture rate is 90% for both designs but the quantity of captured CO2 per ton of cement is significant better for Case 3 (calcium looping). Another important aspect which reflects better performances of calcium looping design in comparison to gas-liquid absorption is the fuel ancillary consumption which is about 52% lower (154MWth vs. 234MWth).
The next evaluation targeted the economic performances of the cement plant with carbon capture. For estimation of the capital expenditure (CAPEX) as well as the specific investment costs (reported as Euro per ton of cement), the cost correlation method was used (Smith, 2005). The key mass and energy flows processed through each main plant systems (e.g. cement plant, carbon capture unit, CO2 conditioning, air separation unit, power plant etc.) were considered as scaling parameters e.g. captured CO2 flow and heat provided to the looping reactors (as well as their volumes) were consideredas scaling parameters for gas-liquid absorption and calcium looping cases (Romano et al., 2013). The complete methodology of capital cost estimation using the cost correlation method is presented by Cormos (2016b). Table3 presents the specific capital investment for the main plant components as well as the total value.
As presented in Table3, the specific capital investment costs for cement plants with carbon capture are higher than for the cement plant without carbon capture (benchmark case) by about 112% for Case 2 and about 75% for Case 3. The calcium looping technology shows significantly lower investment costs than the gas-liquid absorption design due to higher energy efficiency and lower energy penalty for carbon capture.
The operating expenditure (OPEX) was estimated using a commonly used methodology (Peters and Timmerhaus, 1991). The OPEX costs can be broken in two main components: fixed and variable costs depending on their variations with plant output. Figure2 presents the fixed and variable OPEX costs for the investigated cement plants. The carbon capture designs have higher OPEX costs compared to benchmark case with about 90% for gas-liquid absorption case and about 60% for calcium looping case.
The cement production cost significantly increases when CO2 capture is applied (95% for gas-liquid absorption and 63% for calcium looping) as well as CO2 avoided cost. However, calcium looping method shows far better values than gas-liquid absorption.
The audited cement plant contains nearly 94 Mots whose power is greater than 18 kW and that are not equipped with VFD. These Mots belong to the IE1 energy class (according to the classification of IEC 60034-30). Table 11 presents the main operating characteristics of these Mots.
From Table 11, it can be observed that several Mots operate at low charge levels (e.g., Mot 12, 33, 41, and 52). Therefore, installation of VFD for these electric Mots could be considered as a potential solution to reduce energy consumption.
The Ramla cement plant (see Fig. 1 for an aerial photo of the plant) has been in operation for 46 years. The original process at the Ramla cement plant to produce cement from limestone, which is the base material of cement, was a so-called wet line process. The original wet line had a capacity of 1,800 TPD (Tons Per Day). The first new production line producing cement through a so-called dry line process was commissioned in 1994. This line has a capacity of 5,000 TPD and is very successful. Building on its success, Nesher decided to build a second dry line. On the 10th of August 1997, Benjamin Netanyahu, Israel's former Prime Minister, laid the cornerstone at the Ramla plant for the second 5,000 TPD dry line. The new dry line, which is currently in the running-in stage, will join its 5,000 TPD sister dry line and the older 1,800 TPD wet line. The wet line will be phased out soon and thus the anticipated new total plant capacity will be 10,000 TPD. To save costs, Nesher decided to use the existing limestone handling and transport facilities to handle the increase in transport loads. This was made possible by relatively minor modifications to the existing infrastructure. in particular to the belt conveyor system. The raw materials needed to supply all three plants are now transported from a quarry 3.5 km away from the plant via the existing (upgraded) conveyor belt system.
Cement plants have been conserving water in their plants from the beginning as most cement plants have had to make their own arrangements to obtain water required for the plant and for drinking and household purposes.3.1.1.Cement plants procure water from the nearest perennial sources of water like rivers and streams by digging wells in their beds and pumping it and storing it in the plant/quarries/housing colony.3.1.2.Plenty of water is required even in dry process cement plants to cool bearings, compressors, after-coolers, gearboxes and for conditioning towers preceding ESPs. All water used for cooling is invariably collected and taken to a cooling pond and recirculated in the system. Only 10-15% water is added to allow for loss by evaporation.3.1.3.Process water is not required in a dry process cement plant. However if an ESP is used to clean preheater exhaust gases, a cooling tower is necessarily installed to bring down the temperature to about 140C. Gases are cooled by spraying water on the gases in the cooling tower. Water evaporates and is consequently lost. This is a significant quantity.3.1.4.This loss of water can be avoided if the ESP is replaced by a bag filter. However penalty there is a penalty for the higher pressure drop in the bag filter and the necessity of cooling gases to ~120140C by admitting ambient air to suit the materials of bags. If glass bags which can stand a temperature of ~275C are used this dilution can be avoided. Generally speaking the ESP can be avoided at the design stage itself if the plant is located in an area of scanty rains and water scarcity.Performance of the ESP is uncertain during startup and closing down periods. Presently the trend is to avoid an ESP for this reason also.
Plenty of water is required even in dry process cement plants to cool bearings, compressors, after-coolers, gearboxes and for conditioning towers preceding ESPs. All water used for cooling is invariably collected and taken to a cooling pond and recirculated in the system. Only 10-15% water is added to allow for loss by evaporation.
Process water is not required in a dry process cement plant. However if an ESP is used to clean preheater exhaust gases, a cooling tower is necessarily installed to bring down the temperature to about 140C. Gases are cooled by spraying water on the gases in the cooling tower. Water evaporates and is consequently lost. This is a significant quantity.
This loss of water can be avoided if the ESP is replaced by a bag filter. However penalty there is a penalty for the higher pressure drop in the bag filter and the necessity of cooling gases to ~120140C by admitting ambient air to suit the materials of bags. If glass bags which can stand a temperature of ~275C are used this dilution can be avoided. Generally speaking the ESP can be avoided at the design stage itself if the plant is located in an area of scanty rains and water scarcity.
The steam is condensed in condensers and returned to the circuit. Water used to condense steam is itself cooled in cooling towers operating in a closed circuit; that water is used again by recirculation. Therefore, only makeup water is required. The same is true of waste heat recovery boilers. Even where DG sets are used to generate power, diesel engines are cooled by water which in turn is cooled in cooling towers and returned to the circuit.
This water is generally wasted after use, though sewage water can be used after treatment for nondrinking purposes like gardening. As a matter of fact authorities who sanction a cement plant project stipulate that a sewage treatment plant has to be installed in the plant. There should be zero effluent discharge from the plant.
Often, as mines get developed, underground resources of water become available and actually supplement the main source of water. Pits in excavated/exhausted mines can be used to serve as reservoirs of water. These are available year round for mining machinery and crushing plant when located in mines.
Often, currently, used mines are consciously developed and landscaped to serve as recreation or picnic spots. Reservoirs in mines thus serve a dual purpose, as a source of water and as lakes. When treated the water can also be used in swimming pools.
Presently there is great emphasis on greening of the plant and its surroundings, including the housing colony. Green belts are created around the plant and colony to serve as dust and sound barriers. It is mandatory to create such belts between the plant and the highway/township.
In the context of cement plants, rainwater harvesting (RWH) has many dimensions.1.Rainwater is collected and stored in natural/artificial ponds or lakes to counter the salination of groundwater in coastal areas.For this purpose check dams are constructed across streams and rivulets.2.A system called garland canals is constructed to collect the groundwater and lead it to reservoirs in quarries or reservoirs created by check dams.This water can be used in the cement plant for manufacturing, in captive power plants, and for domestic use in colony.As a matter of fact many cement companies are supplying water for drinking purposes and for agricultural purposes to neighboring communities on an increasing scale. Some have installed desalination plants also.The authorities sometimes stipulate that the cement company should not draw water from an adjoining river/stream.3.RWH is used to recharge bore wells within the plant's own area and colony.Water is collected from rooftops and led through pipes to collection pits near the bore wells to recharge them. Water is then available year round, even in summer months.
As a matter of fact many cement companies are supplying water for drinking purposes and for agricultural purposes to neighboring communities on an increasing scale. Some have installed desalination plants also.
Extracts from a typical letter of consent for a cement plant project at a green field site or for an expansion show the emphasis the authorities are putting on water conservation. Cement plants of the future will have to be green. See Annexure 1.
Waste oil is a unique hazardous waste with a long history of utilization. Typical sources of waste oil include automotive oils, machinery cutting and cooling oils, and other sources of lubricants. The opportunities to use this material as an opportunity fuel are worldwide. U.S. waste oil production and consumption exceeds 4.2 109 l/yr (1.1 109 gal/yr), of which 67% is burned as fuel and another 4% is rerefined . A significant quantity is generated in Canada annually as well. Blundell  reports that 200 106 250 106 l/yr (53 66 106 gal/yr) of waste oil is generated in the Ontario province alone; of this 15% is burned in cement kilns, 7% is burned in small furnaces, and 27% is refined again.
In the United Kingdom, 447,000 tonnes of waste oil are generated annually, of which 380,000 tonnes are usedlargely as fuel . Significant attention has been given to this waste disposal problem/energy resource opportunity in such other locations as Bulgaria , New Zealand , Spain , and throughout the European Union. States from California  to Vermont  are paying particular attention to waste oil, its use as a blending fuel, and its proper disposal.
The general fuel characteristics of waste oils are shown in Table 5.21. Note the differences between mineral oil and synthetic automotive oil. Note also the broad range in properties, particularly as associated with mineral oil.
Typical trace metal concentrations have also been measured in waste oils, as shown in Table 5.22. Note that there are significant differences between typical concentrations in the United States and in New Zealand.
There are three basic uses of waste oil as a blending fuel: in small space heaters and boilers, in larger boilers, and in cement kilns. Of these, cement kilns are the most prominent due to their continued search for low-cost alternatives to coal, oil, and traditional energy sources. In New Zealand, for example, two cement kilns dominate the use of all waste oil in that country. Typical emissions from the combustion of waste oil in various applications are shown in Table 5.23. Note that SO2 is not shown in this table because of its dependency on the sulfur content of the incoming fuel.
Given the typical emissions associated with firing waste oils, it is useful to consider case studies of firing waste oils in cement kilns . Therefore, an example of cofiring waste oils in cement kilns in Germany is presented.
A study utilizing data from cement plants in Germany was done to estimate the emissions of various metals as a function of waste material . There are 76 cement kilns in operation, of which 40 are permitted to use alternate fuels such as tires, waste oil, waste wood, and so forth. A typical cement kiln consisting of a raw mill section, a preheater-rotary kiln section, and a cement mill section was used to describe cement production in Germany. Using partitioning factors based on information from operating kilns, a mass balance model was developed for this typical kiln. Using this information, elemental distributions were calculated for cadmium, lead, and zinc when using waste oils at the maximum allowable rate of 30%. The results are shown in Table 5.24. The results show that nearly all the trace metals exit with the clinker, and destruction and removal efficiency (DRE) numbers for the three metals are estimated to be 99.96% for lead, 99.95% for zinc, and 99.94% for cadmium.
A green cement plant is one that is designed to conserve natural resources of all kinds and that contributes to the release of the greenhouse gases (GHG) to the atmosphere to the least possible extent consistent with the quality of cement produced.
Release of CO2, a greenhouse gas, is inherent in the process of the manufacture of cement, as CO2 is released from limestone, the basic raw material of cement during the process of calcining. One kilogram of calcium carbonate releases 0.44kg of CO2. Therefore, in making 1kg of clinker, approximately 0.51kg CO2 gets released into the atmosphere.
A vital component of total carbon dioxide released to the atmosphere is the CO2 released in the process of combustion of fuel fired in the kiln and calciner in the clinkerization process. The quantum released is directly related to the quantum of fuel fired and the quantum of carbon in it.
Again, by the same logic, the obvious way to reduce emissions is to reduce the heat requirement, or what is called specific fuel consumption, and/or to use fuels with less carbon or those that are carbon neutral.
Alternate fuels have been successfully used in many countries in kilns and calciners. In Europe the cement industry is progressing toward zero fuel costs. Great possibilities exist for using wastes of industry and agriculture that have heat value as secondary fuels in kilns and calciners.
Production of cement also requires a supply of electrical energy, expressed as kwh/ton of cement. Electrical energy is presently produced mostly by burning fossil fuels like coal and oil. Thus reduction of electrical energy by making cement indirectly means a reduction in electrical energy produced and thereby in GHG released to the atmosphere. If 1 kwh is used in a cement plant, the generating station has to produce much more to allow for transmission losses and for its own inputs. In some countries transmission losses are small, say 10%, but in some countries (India for one) they are more than 30%.
Cement plants can further contribute significantly to reducing GHG emissions by converting waste heat in the exhaust gases from the kiln and cooler into electricity using waste heat recovery systems (WHRS). There is plenty of scope in existing dry process cement plants to produce power from waste heat.
Due to recent developments in technology it is now possible to generate power even from waste gases in modern cement plants with low heat contents by using the organic Rankine cycle and the Kalina process. It is estimated that between 20 to 30% of the energy required by a cement plant can be generated by installing WHRS. Energy so generated can be used in the plant or fed to the grid.
All fossil fuels emit CO2. Biomass fuels are carbon neutral. Sources of energy like wind, solar and hydraulic are not only totally free of carbon but on top are renewable, and also inexhaustible. Increasing attention is being paid to making them viable sources of energy.
Thus, making or designing a green cement plant in effect means:1.providing facilities for making blended cements in an adequate measure2.designing components like calciners to reduce obnoxious gases like NOx, SO2, etc.3.provide providing for processing and firing alternative fuels which will reduce the quantum of CO2 released4.designing burners and firing systems for available alternative fuels5.if required, providing for bypass of kiln gases which can contain excessive alkalis and chlorides as a result of firing certain alternative or waste fuels6.providing for waste heat recovery systems to generate power or for other applications7.consideration of making composite cements, which are a form of blended cements1.8.1.To this list will soon be added:1.using/making substitute cements2.using renewable energy
There are developments which aim at reducing the GHG emissions by physically collecting CO2 emitted and storing it and making it available to other industries that have use for it, and even for making cements of new types.
Apart from the two major aspects described regarding sustainability and GHG emissions there is more to making a cement plant green:1.keeping the environment green by planting trees and taking up schemes for afforestation2.adopting more scientific mining methods that cause minimum damage to the environment by minimizing mining footprints3.reclaiming used mines for landscaping, creating water reservoirs, etc.4.creating green belts in and around plant and colony5.installing water conservation schemes like rainwater harvesting, water treatment for recycling6.designing and constructing green buildings in the cement plant wherever possible to make maximum use of natural light, ventilation, etc.
The cement industry is consciously making efforts in various areas (listed in section 1.8) and is very much interested in making existing plants green and in designing new plants as green plants.1.11.1.Blended cementsPresently almost all cement plants the world over are making blended cements. In India itself ~ 74% of cement made is blended cement. Slag adding up to 60% has been used up. Fly ash is available but further increase in the quantum of Portland Pozzolana Cement (PPC) is limited unless the ceiling to which fly ash can be added is raised. This change can only be sanctioned by national entities that govern standards of cement, like the Bureau of Indian Standards in India.1.11.2.Alternate fuelsThe main problem is the selection of a fuel that is steadily available in required quantities over a long period of time and which would have reasonably uniform physical and chemical properties, such as calorific value.1.11.3.Waste heat recoveryIntroducing waste heat recovery systems requires heavy capital investment and therefore requires careful planning and engineering.In the subsequent sections and chapters all these aspects have been covered in detail so as to present a comprehensive picture of what it takes to make a green cement plant.
Presently almost all cement plants the world over are making blended cements. In India itself ~ 74% of cement made is blended cement. Slag adding up to 60% has been used up. Fly ash is available but further increase in the quantum of Portland Pozzolana Cement (PPC) is limited unless the ceiling to which fly ash can be added is raised. This change can only be sanctioned by national entities that govern standards of cement, like the Bureau of Indian Standards in India.
The main problem is the selection of a fuel that is steadily available in required quantities over a long period of time and which would have reasonably uniform physical and chemical properties, such as calorific value.
All over the world, sizes of cement plants have increased both as single production units and also in terms of total capacity in one place. Basic processes and, hence. stages of manufacture in green cement plants are the same as those in conventional cement plants. When making blended cements, both the requirements of limestone for a given capacity of the plant and also the area for mining lease reduce drastically.
With the size of the plant capacities of individual machinery, units like crushers, mills, and kilns also increase correspondingly. Therefore, increases in the size of a plant should be accompanied by growth and developments in cement making machinery so as to maintain, and even improve, efficiency and productivity of cement plants.
It is economical to have a single production unit for a given capacity. This would have been difficult without developments like low pressure drop cyclones for preheaters, vertical roller mills with multi drives, high efficiency separators, roller presses, and a number of ways these can be integrated in circuits. Various developments in designs of clinker coolers with+70% efficiencies, developments in designs of low nox calciners, and two support kilns are just some of the developments that have made large green cement plants a reality. Features like co-processing alternate fuels and waste heat recovery systems are also integral parts of large green plants.
With the size of the plant, the quantities of bulk materials to be handled and stored increase correspondingly. A balance has to be struck between economy and continuity of operation in planning layouts of large cement plants. Multiple units are installed to maintain continuity of operation in the event of breakdowns.
New, large plants make at least two types, sometimes more, of cements. Hence, sections of cement grinding, storage, and dispatches have to be planned carefully to cater for the market in the best possible manner. Dispatches can be by road, rail, (even by sea in case of exports), and in bagged or bulk cement. The plant has to plan its facilities carefully, taking these factors into account. Split location has become common.
Operating efficiencies of large plants are highsp. fuel consumption is around 650 - 700kcal/kg clinker; sp. power consumption is between 65-80kwh/ton; and man hours required per ton of cement are as low as 0.15.
Because of their size, it is possible for large plants to invest in renewable energy, such as solar or wind power. Automation and process control are of an advanced nature. New concepts using key performance indicators (KPI ) and dashboard control are coming in vogue. Large plants have to integrate and manage three or more power systems like grid power, captive thermal power, waste heat recovery power, and also solar or wind power. This, itself, is a challenging job.