Abstract

Based on the advantages of cement enterprises entering the mechanism aggregate industry, many years ago, our cement enterprises have been involved in mechanism aggregate on a large scale, and stacker-reclaimer has been widely used in production. However, with the development of the company's business, the loading and unloading capacity of bucket wheel stacker-reclaimer can not meet the needs of overall improvement. In order to meet the new production requirements, while considering the economy, according to the actual situation of the company's production, the limestone conveying system for transformation and upgrading, in order to meet the normal production of aggregates during the rainy season, to adapt to the demand of the aggregate market, the transformation can improve the company's profitability to a certain extent.The stacker-reclaimer is a special stacker-reclaimer for the bulk yard. China began to design bucket-wheel stacker-reclaimer in the mid-1960s, and it has a history of more than 30 years. These stacker-reclaimer machines are mainly used in large bulk ports, coal storage yards of thermal power plants, ore and coal raw material yards of large steel companies, large cement plants and other large enterprises. Therefore, in view of the problem of aggregate production during the rainy season of our company, we can improve the production capacity of the stacker and reclaimer and solve the bottleneck problem of system production.

1 Project Overview

Using its own limestone mining resources, the company has completed the construction of a complete mechanism aggregate production line, the scale of annual production.120Tons of aggregate mechanism sand. The aggregate production line has been2020Year5In the rainy season (6~9During the month), due to the high moisture content of the incoming material from the mine shaft, the high moisture content of the aggregate and the machine-made sand, the powder cannot be selected normally by the powder separator, and the quality of the machine-made sand is unqualified, which affects the normal production of the aggregate during the rainy season, resulting in the shutdown of the aggregate for material and the cut-off of supply, which seriously affects the normal production and operation of the aggregate. In view of the problems existing in the aggregate production line, the limestone conveying system is now upgraded according to the actual production situation of the company, and the first-line limestone pre-homogenization circle pile is used as the transfer warehouse of the aggregate project, so as to meet the normal production of the aggregate during the rainy season and meet the demand of the aggregate market. The original second-line limestone pre-homogenization circle pile is used as the limestone supply homogenization warehouse of the 1. second-line cement kiln, the completion of the project can improve the profitability of the company to a certain extent.

2 Reasons for project transformation

（1) There is no intermediate storage for raw materials in aggregate production, and limestone with low moisture content cannot be stored on sunny days, which is caused by a heavy rain.3~4Days can not normal aggregate production.

（2) After heavy rain, limestone with low water content in the shaft is poured into the shaft on the same day, which has already been crushed and transported to mud removal and screening.18:00After sometimes20:00, resulting in a shorter aggregate production time on the same day, affecting aggregate production.

（32) During the peak-shifting shutdown of the two kilns, the aggregate cannot be produced after the aggregate production sieve fills up the two limestone circles, resulting in shutdown.

（4) The imbalance between aggregate sales and production varieties leads to the problem that some products cannot be produced when the warehouse is full and some products are out of stock and out of supply (it is necessary to build a finished aggregate stacking shed and another plan to solve it).

3 Transformation objectives and ideas

3.1Transformation objectives

in guarantee2#Under the principle that the reserves of the round reactor remain unchanged and the homogenization method and effect remain unchanged,2 # Φ80mThe reclaim capacity of the circular stack reaches750 t/hAbove, meet2The limestone consumption of the clinker production line needs (6 500 t/d 4 200 t/d), and the equipment reliability reaches99%.

3.2reform ideas

ExistingФ80 mThe limestone round stacker-reclaimer is produced by Liyang Sinoma, with a total stock28 000 tThe stacking method is continuous composite, and the stacking capacity is1 000~1 100 t/h, reclaim capacity550 t/h, transformation direction and ideas:

（1) The stacker will not change greatly as a whole, and the central column, rotary, cantilever and pitching devices will remain unchanged. Only the central column collector, cloth belt and other parts will be matched and optimized.

（21) Continue to increase the height of the material pile during the material distribution, aiming to further increase the effective stroke distance of the scraper, so that the material gradually fills the material load volume of the scraper, and once again optimize the homogenization of the material.

（33) Change the structure, installation position and driving force of the rake system, increase the area and depth of the rake tooth disturbance pile, and improve the rake rate.

（43) Improve the scraper filling rate of the reclaimer system, ensure that the material can enter the scraper space volume effectively and instantly, fill the scraper load volume quickly, and improve the scraper running speed.

（5) Increase the space volume of the scraper and the load volume to further ensure the smooth operation of the scraper, and improve the chain tensioning device to ensure that2The root chain tension is the same and balanced. Independent hydraulic tensioning device.

（61) Increase the traveling speed and power of the main vehicle, the raking rate of the batch rake system and the filling rate of the reclaim system.

（72) The reducer is still selected from the original Flanders brand to ensure reliability.

4 Capacity Accounting of Each Conveying Equipment of Limestone Pre-homogenization System

4.1Analysis of limestone supply in two clinker production lines

The daily limestone demand of the two clinker production lines is about14 064 t/dThe clinker output of the first-line cement kiln is as follows4 200 t/dThe output of the second-line cement kiln is calculated6 500 t/dmeter.

Two lines of limestone conveying system750 t/hAfter that, the normal daily feeding time is about14 064/750=18.75 h, the daily utilization rate is about78.13%To meet the normal operation of the two production lines. In case of abnormal conditions such as maintenance or failure, a line round pile can be used to supplement the feed when the feed is insufficient to maintain the normal production of the cement line.

According to the reserves and actual batching situation of the second-line raw material batching bin of the 1., the calculation is as follows:

Limestone storage volume of first-line raw material ingredients1 100 t(Actual capacity is900 t), the capacity of the limestone batching scale at the bottom of the warehouse240 t/h; Limestone storage capacity of second-line raw material ingredients2 500 t(Actual capacity is2 000 t), the capacity of the limestone batching scale at the bottom of the warehouse375 t/h. Capacity of limestone reclaimer of two lines after transformation750 t/h. According to the above situation, when two lines share two-line limestone pre-homogenization, the reasonableness of the switching time of the limestone conveying system between 1. two-line batching bins is as follows:

When the limestone feeding system feeds the first line, the full time of limestone batching bin is about:h1=900 t/（750 t/h-240 t/h)=1.76 h; The time from full warehouse to empty warehouse is about:h2=900 t/240 t/h=3.75 h.

When the limestone feeding system feeds the second line, the full time of limestone batching bin is about:H3=2 000 t/（750 t/h-375 t/h)=5.33 h; The time from full warehouse to empty warehouse is about:h2=2 000 t/375 t/h=5.33 h.

From the above data and the supply and demand relationship of limestone in the two production lines, it can be seen that in normal production, the limestone conveying system feeds the second-line batching station.5.33 hAfter that, it can be switched to the first-line batching station for feeding.1.76 hAfter that, the reclaimer can be shut down.3.57 hAround, make another supplement. The material can also be divided by the material dividing valve and fed to the second line of the 1. at the same time.

 

In addition, the first-line limestone pre-homogenization storage yard can still normally supply materials to the first-line raw material batching station in the case of non-rainy season, and only during the rainy season can it be used as a temporary limestone transfer warehouse for aggregate production.

Therefore, during the rainy season, the switching frequency of the second-line limestone reclaimer to the second-line raw material batching station of the 1. is reasonable, and the selection of the production improvement capacity is reasonable.

4.2Analysis of limestone supply in aggregate system

Limestone (oversize) is required daily for normal aggregate production4 000 tThe reserves of the existing first-line limestone pre-homogenization yard are24 500 t, the storage period is6.12 dThe amount of aggregate ex-factory will decrease during the rainy season, and the completion of the project is expected to ensure the rainy season.7~10 dThe supply of aggregates; two cement production lines can also be supplied after the simultaneous peak shutdown.10 dLeft and right aggregates.

According to the above analysis, the second-line limestone pre-homogenization yard can meet the limestone supply of the two kiln production lines, and the first-line limestone pre-homogenization yard, as the transfer depot of the aggregate project, can solve the problem of aggregate production and supply in the continuous rainy season. Overall evaluation, the project is feasible.

5 Modification scheme

（1) Solve the height (I. e. design height) that the material pile should have, and after modification, ensure that the cantilever is tilted up. 15°When above, the belt of the stacker belt conveyor will not slip or lose its rotation at the driving drum, and will not stagnate or plug materials in the guide chute, so it can operate naturally and normally, and the cloth distribution capacity can still reach1 100 t/h.

（2) Increase the cross-sectional area of the material rake to sweep the stockpile, increase the area and depth of the rake teeth to disturb the stockpile, and increase the driving force of the rake.

（32) Increase the space volume of the scraper, correct, adjust and improve the running speed of the scraper, and improve the filling rate of the scraper.

（4) Due to the increase of the walking speed of the material rake and the increase of the walking speed of the scraper taking materials, the walking speed of the cart must also be increased, so as to ensure the harmonious operation of the three, and the materials raked by the material rake can be unimpeded and fed into the space volume of the scraper.

（5) The electronic control system follows the transformation of relevant parts:①Due to the increase in the drive power of the scraper and the power of the oil pump motor of the material rake hydraulic system, it has exceeded.100 kW, need to update a new central collector;②Related cables and electrical components must also be added with large capacity.

6 Benefit analysis

After the transformation, it can not only ensure the limestone supply of the two cement production lines, but also ensure the continuous operation of the aggregate production line during the rainy season. The annual rainy season is calculated as two months, and each month is affected by the rainy season.20 daccounting, the resulting profit is approximately: (selling price35Yuan/t -Cost price15Yuan/t)× 4   000 t/d× 20 D = 160Ten thousand yuan, the annual rainy season continuous production can produce.320Ten thousand yuan profit, less1The cost of the investment can be recovered in years. Therefore, the transformation project has good economic benefits.

Through the technical transformation of the limestone stacker-reclaimer, the original unreasonable parts of the equipment are repaired, and the overall operation of the equipment is good. After the actual operation of the equipment, the technical transformation of the stacker-reclaimer basically achieved the expected effect.