Discussion on energy saving in operation adjustment of desulfurization wet ball millDate: 2019-07-03 Views:
1 Desulfurization wet ball mill system introduction
Wet ball mill is an important 6KV equipment for desulfurization systems in most thermal power plants. How to use the operation adjustment method to reduce the desulfurization system power consumption is a topic worthy of discussion in the operation of the desulfurization system. The wet ball mill of the equipment for desulfurization is a high-power equipment for the desulfurization system. How to reduce the power consumption of the wet ball mill and maintain its optimal operation state with low energy consumption and high parameters is the focus of this paper.
It is composed of horizontal cylinder, hollow shaft and oil system, etc. The limestone and process water are fed by the wet grinding inlet. The hollow shaft enters the cylinder body. When the ball mill cylinder rotates, due to the action of inertia and centrifugal force, the limestone and water are brought up by the cylinder on the cylinder liner. When it is brought to a certain height, due to its The gravity itself is thrown away, and the falling material falls along the parabola, crushing the limestone. The ground limestone slurry is discharged through a hollow journal to a mill slurry tank, and the slurry is pumped to a cyclone separator through a mill slurry, and the milled limestone slurry is separated by coarse and fine particles by a limestone swirling action. The large particles are separated into the bottom of the cyclone separator to form an underflow thick slurry, which is returned to the ball mill for re-grinding; while the small particles in the slurry overflow from the top to form a slurry into the limestone feedstock tank for backup Pulp and DCS system). We set up 3 wet ball mills , corresponding to each wet ball mill with 100% capacity limestone hydrocyclone, each output according to 4 boilers BMCR working conditions when burning coal. The device needs to be considered at 50% of the amount of limestone and meets the requirements for the check coal. When the whole set of 4 sets of desulfurization equipment was put into operation, two sets of mills under the coal type were designed to run, one set of mills was used for backup, and three sets of coals were checked. #3,4 Desulfurization system set up a 435m3, limestone slurry tank. #1, 2 desulfurization system set a 435m3, limestone slurry tank.
2 wet ball mill operation adjustment and energy saving
2.1 Current monitoring and energy saving in the operation of wet ball mill
The load of the steel ball has a great influence on the pulping system, which is also the main reason for the increase of the power consumption of the pulping system. If the steel ball is insufficient, the wet grinding output is lower than the design working condition, the slurry density, the fineness, the power consumption, and the material. It is difficult to achieve the best balance. In the wet grinding operation, the limestone particles are impacted, squeezed and ground into a slurry by steel balls. If the steel ball is insufficiently loaded, the fineness will be difficult to meet the design requirements. During operation, the ball load can be monitored by monitoring the main motor current of the ball mill . If the current is found to decrease significantly, it needs to be replenished in time. Steel ball. Through the operation experience, with the wear of the steel ball, the steel ball is generally only supplemented with the model with the largest diameter. It can be added according to the trend of the current reduction of the wet grinding operation after running for a period of time, generally for about 1 month, try to keep it. Less and more, in order to keep the operating parameters as stable as possible, as close as possible to the rated operating conditions.
2.2 Water-to-feed ratio in the operation of wet ball mill
The ratio of water and material in the operation of the wet ball mill should follow the following parameters (combined with the operating rules and summarize the actual operating experience): the ratio of the amount of limestone in the wet ball mill to the process water is about 3:1, and the grinder tank replenishes water and The ratio of limestone usage is about 2:1, and the limestone slurry density is adjusted to 1250kg/m3. Check and check whether the water to material ratio is within the specified range. When the water volume is large, the flow rate is fast, the milling time is relatively short, the particle size of the slurry is relatively large, the reaction area of the limestone slurry in the absorption tower is reduced, and the limestone raw material is wasted more; when the water is low, the slurry density is increased, when severe , causing undesirable phenomena such as pipe blocking. Therefore, maintaining the optimum water mix ratio is the basis for wet mill economic operation.
2.3 Monitoring of fineness of limestone slurry at the outlet of wet ball mill
The principle of fineness adjustment of limestone slurry is to minimize the power consumption of the milled mass quality slurry. The finer the fineness of the particles in the limestone slurry, the larger the chemical reaction contact area of the equal amount of limestone slurry in the absorption tower, and the more complete the reaction. Desulfurization efficiency, gypsum slurry quality, and dewatering effect will be better. However, if the fineness of the particles in the limestone slurry is too fine, the number of cycles of the limestone slurry in the pulping system will increase, which will inevitably increase the power consumption of the pulping system. The purpose of the operation adjustment of the wet ball milling system is to make the finely ground limestone slurry. The degree and density meet the requirements of the desulfurization process, and reach the design value to ensure the safe and stable operation of the system and the lowest energy consumption.
According to the operation adjustment experience, the limestone fineness should be regularly tested and tested to provide effective adjustment and monitoring means for the operating personnel. In addition, the density of the limestone slurry is controlled to 1200 to 1300 kg/m3, and at the same time, the comparison is performed by means of tests and the like to ensure the accuracy of the fineness and density of the limestone slurry. When the density of limestone slurry is found to increase abnormally, slurry deposition may occur in the pipeline, the limestone is closed to the main gate, and the flushing door is opened to flush the pipeline. If the effect is not obvious, the manual door on the local active pipeline will be normal. In short, the principle of operation adjustment is to minimize the power consumption of the grinding unit quality slurry. Generally, the operating parameters are adjusted through multiple operations, and the optimal operating values are obtained after summarization.
2.4 Inspection and acceptance of limestone particles
The size of limestone particles is related to energy conservation. When the limestone particles (particle size ≤ 20mm) are large, it will inevitably cause a long time in the wet grinding, and the slurry of the same quality will consume more electricity. The limestone purchased by our factory is transported to the power plant by car ,discharged into the limestone discharge hopper, and sent to the steel limestone silo through the mechanical vibrating feeder and bucket elevator. Then, the weighing machine is sent to the wet ball mill to add water to grind to form a slurry. The limestone slurry is pumped to the hydrocyclone and separated, and the large particles of the underflow material are recycled to the ball mill inlet, and the concentration is about 30%. The limestone slurry having a solid particle size of 44 μm (325 mesh, 90% pass) overflows into the finished slurry tank and is then pumped through the limestone slurry to the absorption tower.
In normal operation, the acceptance criteria should be strictly checked. Our factory adopts the materials company, equipment maintenance, equipment operation departments to jointly accept and sign, and sign the acceptance form to ensure that the limestone particles are qualified, the water is normal, and the impurities (including soil and limestone powder) Etc.) In the standard range, ensure that the pulping is safe and economical.
2.5 Operation and maintenance of limestone pulping system
In order to maintain the safe and stable operation of the pulping system and avoid the occurrence of various anomalies, the operation parameters are adjusted and the inspection and maintenance of the operation process are completed, which lays a foundation for the economic operation of the pulping system.
2.5.1 Maintain the rotating machinery according to the general rules for running and maintenance of rotating machinery.
2.5.2 A, B, C pulping system is rotated.
2.5.3 The grinding machine idle time shall not exceed 10 minutes.
2.5.4 The pressure of the cyclone system is maintained at about 0.42 to 0.45 KPa.
2.5.5 If the cyclone is found to be clogged, contact the inspection and repair in time.
2.5.6 Check that the belt of the weighing feeder is not deviated, and there is no material under the belt.
2.5.7 The mill stops running for more than 3 days, and when there is no maintenance task, the high pressure oil pump is turned on for two minutes every 24 hours.
2.5.8 The oil level of the lubricating oil tank should not be lower than 1/2. If necessary, carry out oil filling in the fuel tank.
2.5.9 Contact and repair, clean the low pressure oil pump outlet filter once a month.
2.5.10 Low pressure oil pump rotation operation.
2.5.11 mill slurry circulating pump is used alternately.
2.5.12 A, B wet grinding normal current is maintained at 90 ~ 95A, C grinding current is maintained at 86 ~ 92A, A, B wet mill current is lower than 90A (C grinding is lower than 88A), timely contact with maintenance repair steel ball .
2.5.13 The inlet water to material ratio of the mill is kept in the best economic operation state, and the calibration is often verified.
2.5.14 The slurry in the grounding trench should be cleaned in time to prevent the limestone slurry from overflowing.
2.5.15 The pulping system is used for a long time, and the weekly shift is 15 minutes on a slow shift.
Through the above-mentioned adjustment means, while ensuring the safe operation of the desulfurization pulping system, the optimal economic operation state is maintained. After the statistics of the pulping system power and the comparison before and after the adjustment means, the statistics of the 6KV wet grinding switch power show that the power saving is about 17-21%, and the energy saving effect is obvious. In addition, through the pulping system operation cycle The shortening reduces the wear cycle of the wet-grinding liner, and the limestone fineness and density are reasonably adjusted. Under the same effect, the consumption of limestone and water is reduced, and the potential economic benefits are obvious. We will continue to work hard to sum up experience, optimize operating parameters, and strive to create the best level of operation of our pulping system.