Technology | Energy-Saving Retrofit Of Raw Meal Grinding System

The designed production capacity of a cement clinker production line is 5000t/d. The raw meal grinding system adopts two MLS37.26 roller mills. The output of a single roller mill system is 210-220t/h. , 200μm sieve residue is 1.8% to 2.0%. The power consumption of the raw meal grinding system of this production line is 15.7kW·h/t. This power consumption index is within the normal range for the roller mill raw meal grinding system, but compared with the current more energy-saving roller press raw meal final grinding For the system, the power consumption index is slightly higher. At the same time, the production capacity of the two sets of roller mill systems can barely meet the requirements of the firing system, and there are still problems such as high operation rate, short maintenance time, high failure rate and high maintenance cost. To this end, in 2020, the company replaced the original two sets of roller mill systems with a single set of roller press final grinding systems, which achieved the goal of increasing production and reducing consumption, reducing production running time, reducing clinker production costs, and improving product competitiveness. Purpose.

The project adopts the TRP200-160 raw meal roller press final grinding system of Tianjin Cement T Industry Design and Research Institute Co., Ltd. After 6 months of construction, it was put into operation on September 16, 2020. The transformed raw meal grinding system The system is shown in Figure 1 . The following is a brief introduction to the transformation of the system for the reference of colleagues in the cement industry.

01System configuration and operation before the renovation

The configuration of the roller mill system before the transformation is shown in Table 1 , and the process flow of the roller mill raw meal grinding system before the transformation is shown in Figure 2 . In the process of production and operation, after the materials out of the batching station are measured, they are sent to the roller mill for grinding through the belt conveyor. Transfer to raw meal homogenization warehouse.

02 System flow and equipment configuration after transformation

The configuration of the modified roller press system is shown in Table 2 , and the process flow of the modified raw material roller press final grinding system is shown in Figure 3 . In order to reduce the impact of the modification of the raw meal grinding system on the kiln system, the new final grinding system of the raw meal roller press was built on the open space next to the original roller mill. After the construction of the new system was completed, it only took 9 days to complete the connection between the material and the air duct, and the material feeding was successful. The designed output of the modified raw material roller press system is more than 500t/h. The system uses the existing deployment warehouse. After the materials are measured, they are sent to the V-type powder separator through the belt conveyor. The system is equipped with iron remover and detector on the belt conveyor, and a metal separator is installed at the head of the belt conveyor. When a large piece of metal is detected, the metal separator will act to discharge the material containing the large piece of metal into the outer discharge silo, and then return to the grinding system after the iron removal treatment. The fine particles after being selected by the V-type powder separator are brought into the high-efficiency powder separator for sorting by the wind; Another elevator is sent to the V-type powder separator for re-sorting. After the materials entering the high-efficiency powder separator are sorted, the fine powder is collected by the cyclone as the finished product and stored in the warehouse; the coarse powder is returned to the V-type powder separator. , for further sorting or directly return to the small warehouse of the roller press for circular extrusion. The hot air of the system adopts the original kiln tail hot air, and the exhaust gas of the circulating fan is discharged. Part of it is circulated into the V-type powder separator to participate in drying and sorting; the other part enters the original kiln tail dust collector, and is discharged into the atmosphere after treatment.

In order to strengthen the iron removal in the system, an iron removal device is installed at the material chute that returns to the small warehouse after being sorted by the V-type powder separator to remove the metal substances in the system, ensure the safe operation of the roller press, and extend the roller surface. At the same time, an external discharge tee is set to discharge the hard-to-grind materials enriched in the system regularly.

The system has the following advantages in design:

(1) In order to avoid the increase of system load caused by air leakage, a sealed feeder is added in front of the V-type powder separator to ensure that the air leakage of the system is as small as possible.

(2) The selection of the circulating fan in this system has a great influence on the power consumption of the system, and a high-efficiency and energy-saving fan should be selected when purchasing.

(3) The traditional 4 cylinders of the cyclone Jiannan for collecting finished products in this system are changed to 2 cylinders. First, the length of the air duct from the high-efficiency powder separator to the cyclone cylinder is shortened as much as possible, thereby reducing the resistance of the system; the second is to facilitate the symmetrical arrangement, Ensure that the air in and out is even, and the traditional 4 cylinders are easy to deviate from the wind.

(4) For the convenience of operation, the pneumatic gate valve on the upper side of the roller press is changed to pneumatic rod valve.

(5) The high-efficiency powder separator is driven by a permanent magnet motor

03 The operation of the raw meal grinding system before and after the transformation

The operation of the raw meal grinding system before and after the transformation is shown in Table 3 .

(1) The operation index of the final grinding system of the modified raw material roller press exceeded expectations. Compared with before the transformation, the output of the raw meal grinding system is increased by more than 18% (>80t/h), and the power consumption of the system is reduced by more than 30% (4.88kW·h/t).

(2) The influence time of the system transformation process on the kiln system is short. Since the newly added roller press grinding workshop and the original grinding workshop are independent of each other, the original system can continue to produce during the construction of the roller press workshop. When the construction of the roller press system is completed, the original roller mill system needs to be stopped, and the connection parts such as the feeding system and the hot air pipeline need to be constructed. The construction time is only 9 days.

(3) The roller press selected for this project has a large specification and a high system capacity. Although the one-time investment is large, the peak and valley electricity price can be used, and the investment recovery period can be effectively shortened after calculation.