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Grate cooler technical upgrade and transformation program

  At present, in the new dry process cement production line, the mainstream models of the grate cooler are the third and fourth generation grate coolers, and some second generation grate coolers. As the use of equipment continues to increase, wear and tear is increasing, and various problems have arisen, such as: increased mechanical failure rate, affecting the annual operating rate of the kiln; second, tertiary air temperature is low, heat recovery efficiency is low, burning The coal consumption in the system is high; the hurricane is severe, the power consumption of the fan is high; the clinker temperature of the chiller is high, which affects the normal storage and grinding of clinker. Therefore, after long-term operation, the upgrading of the grate cooler is very necessary. This paper introduces the research and development experience of our company's Sinowalk fourth-generation grate cooler, and according to the actual use of different on-site grate coolers, combined with market demand, put forward five options for upgrading and upgrading the grate cooler technology. From the aspects of construction period, energy saving and cost analysis, the characteristics of each scheme are elaborated in order to obtain the optimal technology upgrade plan under reasonable investment.

  1 Sinowalk fourth generation chiller introduction

  In 2008, Tianjin Cement Industry Design and Research Institute launched the first Sinowalk fourth-generation grate cooler with independent intellectual property rights. This product absorbs the advanced design concept from abroad, combined with the domestic mechanical processing and manufacturing level and user feedback experience, the final research and development success, and successfully reached the standard.

  In 2009, the clinker tail roll crusher was successfully developed to replace the hammer crusher. At the same time, the first Sinowalk fourth-generation grate cooler was equipped with a tail roller crusher.

  In 2010, the first fourth-generation grate cooler with an intermediate roller crusher was successfully put into operation. The intermediate roller crusher is located in the middle of the two-stage boring machine, and divides the chiller bed into two. After the clinker is cooled by the first boring machine, it enters the intermediate roller crusher for crushing, and the large block and red core material are broken. It is crushed into clinker with a particle size of about 25 mm, and then cooled by a second stage boring machine. Compared with the tail roll crusher, the cooler equipped with the intermediate roll crusher can obtain a lower clinker temperature and a higher waste heat power generation air temperature.

  The main technical features of Sinowalk cooler are as follows:

  1) The second and third air temperatures are high, and the heat recovery efficiency is high, which is greater than 75%, thereby reducing the system heat consumption;

  2) The temperature of the clinker cooler is low, which is conducive to the storage and grinding of clinker;

  3) The mechanical operation rate is high, and the annual operation rate is 100% (except for regular shutdown kiln maintenance);

  4) There is an automatic air volume control valve under each raft to improve the utilization of cooling air and reduce the cooling air usage, thus reducing the power consumption of the fan. The cooling air volume per clinker is only 1.7~1.9Nm3/kg (due to different on-site clinker) The granules are inconsistent and the air volume fluctuates within this range);

  5) There is a relatively fixed dead layer on the trampoline to protect the raft from the high temperature hot clinker. The life of the raft is more than 5 years, which reduces the cost of spare parts and saves labor costs for replacing spare parts.

  6) Modular design and installation, high installation and manufacturing precision, short construction period of technical transformation site;

  7) For the renovation project, the original casing and foundation can be fully utilized to reduce the civil construction investment and shorten the transformation period.

  In summary, the technical indicators of Sinowalk's fourth-generation grate cooler have reached the international advanced level in the same industry. At present, it has sold more than 140 units and put into production of 120 units, 11 of which are sold overseas, which has been widely recognized by domestic and foreign owners.
 

  2 Five transformation plans and analysis of their respective characteristics

  According to different market demands, combined with the actual operation of the production line, this paper proposes five different transformation plans, in order to obtain the maximum economic and social benefits under reasonable investment.

  Option 1: Overall replacement;

  Option 2: retain the shell and replace the trampoline;

  Option 3: The third generation of grate cooler adds an intermediate roller crusher;

  Option 4: Add a new trampoline to the tail, and the original chiller will remain unchanged;

  Option 5: Replace the fixed slope.

  The following is a detailed analysis of the above-mentioned transformation plan from the four aspects of program description, applicable site, revenue analysis and classic case, and compare their advantages and disadvantages.

  2.1 Option 1

  Solution: The original chiller (third-generation chiller or second-generation chiller) was completely dismantled, all replaced with the fourth generation of Sinowalk chiller, re-creating the civil structure support, supporting the new hydraulic station and lubrication station. According to the needs of the owner, the clinker crusher can be equipped with a tail roll crusher or an intermediate roll crusher.

  Applicable site: The original crucible cooler has long service time, high failure rate, low operation rate, low heat recovery rate, high clinker temperature of the chiller, and the site of clinker production.

  Revenue analysis: The investment in this program is large in the early stage, the construction period is long, and the income obtained is also the largest. Higher second and third air temperature can greatly reduce the system coal consumption; the clinker temperature of the cooler is low; the trampoline has a longer service life and a longer replacement cycle.

  Classic case: a 2500t/d production line of China Resources, Guangxi Zhuang Autonomous Region, using the third generation of cooling machine of Tianjin Cement Industry Design and Research Institute Co., Ltd. before the renovation, model TC1164, the trampoline area is 61.4m2. On August 15, 2013, the kiln was rebuilt. Adopting our company's latest Sinowalk fourth-generation cooling machine, supporting intermediate roller crusher, the trampoline area is 69.5m2. Take the scene as an example to detail the design selection of the transformation.

  Before the transformation, the third generation grate cooler kiln head platform is 10.5m high, the length of the boring machine is 2.7m, the base of the second boring machine is 2.1m, and the clinker zipper base is located on the 0 plane, as shown in Figure 1.

  The newly replaced mechanical structure with intermediate roller crusher and chiller: the boring machine is divided into two sections, and the height difference between the first and second boring machines is 3.4m, so the overall boring machine height is higher than that of the third generation chiller before the transformation. The height of the 10.5m kiln head platform can meet the height arrangement of the intermediate roller crusher cooler. The fourth generation of the grate cooler does not leak material, and the original small zipper can be removed, leaving space for the steel structure supporting the boring machine. After the transformation, the four-generation grate cooler has a boring bed foundation height of 3.4m, supported by a steel frame on the 0-plane, the second-stage boring machine on the 0-plane, and the intermediate roller crusher base is 3.3m high, supported by a steel structure. On the 0 plane, see Figure 2. The new trampoline specification SCLW4-8X10-CM is added. The trampoline has a width of about 3.2m and a length of about 21m. Since the kiln diameter has not changed, the width of the trampoline is basically the same as that of the original boring machine, and only the length is extended, making the entire boring machine The effective area has increased. The on-site boring machine and the intermediate roller crusher are hydraulically driven and equipped with a spare pump. Compared with the drive of the reduction motor, the hydraulic drive has the advantages of high running stability, strong impact resistance, and convenient switching of the standby pump on-line. Significantly increase the operating rate of the system.

  The electrical work involved in the transformation: 1) After the transformation, the hydraulic motor and fan motor of the hydraulic station are replaced again, and the low-voltage control cabinet and the inverter also need to be re-ordered and installed; 2) After the modification and production, the cooling air volume increases, and the installed power of the fan To increase, it is necessary to verify whether the capacity of the kiln head transformer is sufficient; 3) verify whether the head exhaust fan has a margin to remove more exhaust gas; 4) verify whether the DCS control point is sufficient; 5) air cannon system and high temperature industry The camera retains the existing ones and continues to use them without modification.

  At the same time, the preheater was upgraded and upgraded. After the technical transformation, the output of the grate cooler was significantly improved, the coal consumption of the system was greatly reduced, and the clinker temperature of the coffin cooler was about 100 °C, and the waste heat power generation increased. The main parameters before and after the transformation are shown in Table 1. The reduction of the heat consumption per clinker in the table is attributed to the improvement of the heat recovery efficiency of the new chiller and the retrofit of the preheater. The scheme adopts the intermediate roller crusher, and the transformation effect is remarkable and recognized.

  2.2 Option 2

  The scheme stated that the original chiller casing was unchanged, the boring machine was removed, and the fourth generation boring machine was replaced, and the new boring machine hydraulic drive system and electric control cabinet were replaced.

  Applicable site: The original chiller has a long service life, high mechanical failure rate, and low heat recovery efficiency. At the same time, it has little demand for production, and it is necessary to reduce the heat consumption of the system and reduce the production cost of clinker.

  Revenue analysis: This program retains the original shell, saving the cost of the shell and castables (including material costs and construction costs), and can continue to use the original civil construction support, saving civil construction expenses. Less investment, replacement of new trampolines, second and third wind temperature rise, high heat recovery rate, can reduce system heat consumption. However, due to the size of the original casing, the area of ​​the trampoline cannot be increased, and the yield increase after the transformation is not obvious.

  Classic case: A 3500t/d production line in Xinxiang, Henan Province, the original cold machine has a high failure rate and low operation rate. The frequent shutdown of the kiln causes the heat consumption of the firing system to be high, and the secondary air temperature is only 985 °C. In July 2014, the technical upgrading was carried out. The original chiller casing and foundation were unchanged. The boring machine was replaced with the Sinowalk fourth-generation chiller. The photo of the new chiller installation site is shown in Figure 3. As shown in Figure 3, the worker is installing a new trampoline from the end of the original casing. After the technical transformation, the mechanical operation stability has increased significantly, the operation rate is as high as 99%, the secondary air temperature is above 1100 °C, and the clinker temperature of the chiller is 100 °C, the system heat consumption is greatly reduced, and the transformation effect is remarkable.

  2.3 Scheme 3

  The program description: The third-generation chiller boring machine is generally divided into three sections, keeping the first two sections of the boring machine unchanged, removing the third section of the boring machine, adding a middle roller crusher at the original third stage boring machine position, adding a section behind Sinowalk's fourth generation of grate coolers.

  Applicable site: The original third-generation chiller is in good condition, and the intermediate roller crusher is added to increase the output and reduce the temperature of the clinker.

  Revenue analysis: The project has less investment and short construction period, which can reduce the clinker temperature of the chiller and increase the temperature of the waste heat power generation, but has no effect on the heat recovery efficiency of the original chiller.

  Classic case: Zhejiang 5500t/d clinker production line, using the original Tianjin Institute third generation grate cooler TC12102, the trampoline is divided into three sections. The structure of the grate cooler after the technical transformation is shown in Figure 4. The gray part shows the first two sections of the trampoline retained; the green part shows the new Sinowalk grate cooler after the third section of the trampoline is removed; Part of the increase is the intermediate roller crusher. After the transformation, the clinker temperature of the chiller will be greatly reduced, and the amount of waste heat power generation will also increase. The project is currently under design.

  2.4 Scheme 4

  The scheme stated that the original chiller remained unchanged and the crusher moved backwards. A new section of the Sinowalk 篦 cooler was added at the end of the original boring machine, and the corresponding hydraulic system and electric control cabinet system were also provided.

  Applicable site: The original chiller is in good condition, but the temperature of the clinker is high and the clinker temperature is lowered.

  Revenue analysis: The investment in this scheme is small, the construction period is short, and the heat recovery efficiency of the original cooling machine is not affected, but the clinker temperature of the chiller is reduced.

  Classic case: A 6000t/d production line in Guangdong Province, before the transformation, the CP third-generation grate cooler and intermediate roller crusher were used. Due to the increase in output, the clinker temperature of the grate cooler was too high, and the technology was carried out in March 2015. Upgrade, add a section of the Sinowalk 篦 cooler at the end of the original CP 篦 cooler. The area of ​​the original boring machine is 133.5m2, the total boring area after transformation is 173.3m2, the clinker output is 7000t/d, and the clinker temperature of the chiller is greatly reduced, about 95°C, and the waste heat power generation is improved. The structure of the grate cooler after the technical transformation is shown in Figure 5. The red part is the original boring machine, the green part of the tail end is the new Sinowalk 篦 cooler, and the clinker cutting slip is moved later.

  2.5 Scheme 5

  Solution: Only replace the fixed slope, the trampoline does not change, and replace the original slope with the efficient fixed slope of the Sinowalk篦 cooler.

  Applicable site: The original chiller is in good condition and needs to improve the efficiency of heat recovery.

  Revenue analysis: After replacing the high-efficiency fixed slope, the second and third wind temperatures can be greatly improved, and the system coal consumption can be reduced. At the same time, its special air intake mode can effectively avoid the snowboarding problem of the slope and improve the operation rate of the grate cooler.

  The investment in this program is small, the construction period is short, and the transformation effect is obvious, which will be the focus of the next step of transformation.

  3 Five scheme comparisons

  The investment and income comparison of the above five schemes is shown in Table 2.

  Based on the analysis of the above different schemes, in accordance with the operation of different sites, in line with the principle of saving investment and maximizing profits, appropriate technical reforms can be adopted in a targeted manner.

  1) The original chiller has high mechanical failure rate, low heat recovery efficiency, and high temperature of clinker cooler. The following two schemes can be used for technical transformation: production demand, recommended scheme 1; no production demand , recommendation two.

  2) The original chiller machine is reliable in operation, and the alternative modification methods are: if the clinker in the kiln is unevenly aggregated, the bulk material is more, and the recommended scheme is three; if the clinker in the kiln is uniform, the recommended scheme is four; Option 5 can also be used to improve heat recovery efficiency.

  4 Conclusion

  At present, the production of new dry process cement is gradually shifting to the energy-saving, environmentally friendly and resource-based operation track. Sinowalk's fourth-generation chiller has the advantages of high heat recovery efficiency and low operating power consumption, especially the fourth-generation chiller with intermediate roller crusher, which further reduces the clinker temperature of the chiller and recovers more Heat is used for waste heat power generation and coal mill drying to improve heat recovery efficiency and meet the national strategic goal of “energy saving and emission reduction”. According to the actual operation situation of different sites, this paper proposes five kinds of transformation plans, which can be combined with the needs of the owners, and choose one of them to upgrade the cooling machine to bring the greatest economic and social benefits to the owners.

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