Cement separators have become indispensable auxiliary equipment in closed-circuit cement grinding plants, maximizing the effectiveness of cement grinding mills and ensuring the quality of finished products. Osepa separator is a kind of high-efficiency separator widely used since its outstanding features surpass the previous versions of other types of cement mill separators. However, problems still exist when using o sepa separators, especially in winter. The most common problems of Osepa separators in winter are condensation phenomenon and material clogging. Let’s see how the problems affect the operation process and find out the reasons.
Problems of osepa separator in winter
Let’s look at a real case in a cement plant. The company has a double closed-circuit grinding system equipped with a cement ball mill, a roller press, and an O-Sepa separator. The production totally relies on the single cement mill, and the winter production time is long. In the winter production process of the Osepa separator, the air guide vane often has the phenomenon of hanging material blockage, and the bottom of the primary air duct intake is serious. As a result, the grinding system is not well-ventilated, the collection of finished products is greatly affected, and almost every shift has to stop and enter the internal cleaning of the separator. It not only affects normal production, but also the labor intensity is large, causing large economic losses to the company.
Reasons for condensation and material clogging
Temperature differences problem
In winter, the external ambient temperature is low, while the internal temperature of the powder classifier is high, resulting in temperature differences and causing condensation.
Humidity problem
The moisture content of the raw material for manufacturing PO42.5 cement is large. Water vapor is generated and enters the separator with a high concentration of dust from the windpipe. Thus vapor condenses into dew if the temperature drops below a certain degree.
Improper process design
Osepa separator uses the wind inside the mill as the primary source, and the environment wind as a secondary and tertiary source. A cold blast valve on the primary air duct intake is used to increase the volume of primary air, control the amount of ventilation in the mill, and adjust the flow speed of material. There is too much work for the one piece of cold blast valve.
Solutions for the problems of o sepa separator in winter
Reform ideas
Consider replacing the mixed raw materials first to reduce the water content in the mill, and reduce the total amount of vapors. However, there are limited resources available around, and better raw materials are out of reach.
Increase the temperature of clinker out of the mill from 90℃ to 150℃, thus increasing the wind temperature at the outlet of the grinding mill. This is for avoiding the water vapor dew point( normally 50-60℃).
To break the adhesive force of the materials on air guide vanes, the primary wind speed must be accelerated. At the same time, it can not affect the flow speed in the grinding mill. Otherwise, the efficiency of the grinding mill will be impacted, the reloading rate of the separator will be increased, and the separation efficiency will also lowered. As a result, the production capacity per hour is affected and the power consumption is increased.
Reform solution carried out
(1) The gate valve is installed on the air pipe from the cement grinding tail to the powder separator, and the speed of the main exhaust fan is increased from 90 to 100. By adjusting the opening of the gate valve, the wind speed of the separator and the pipeline is increased, and the speed of the materials in the grinding is also controlled.
(2) Make valves at the secondary and tertiary air inlet of the separator, and adjust the secondary and tertiary air inlet with the increase of the primary air inlet. Measure the wind speed with the hand-held wind meter to calculate the total amount of primary, secondary, and tertiary, and adjust it within a reasonable range, that is, the primary air: the secondary air: the tertiary air is equal to 67.5:22.5:10. Through the rational use of air in the separator to reduce the circulating load of materials, improve the powder selection efficiency of the O-Sepa separator.
Modification effect
By adopting the above modification and adjustment, after continuous production for a week, all parameters of the system are normal, among which the grinding temperature of PO42.5 cement is about 75℃. The separator is opened for field inspection, and the air guide vane is clean and has no hanging phenomenon.
There is almost no material at the bottom of the primary air duct, and the inspection results meet the working requirements of the Osepa separator, while the output is stable at about 140t/h, and the power consumption of the cement process is reduced from 340kWh/t to 30kWh/t.
Precautionary measures
Install temperature and humidity sensors
To guarantee that the temperature and humidity inside the separator can be tracked in real-time, install temperature and humidity sensors at strategic points (such as the powder selection area, air inlet, and air outflow).
Decide on a fair dew point temperature. The device will alert the operator to make necessary temperature adjustments when the temperature approaches or falls below the predetermined dew point.
To guarantee the temperature and humidity balance inside the separator and lessen the chance of condensation, connect the temperature and humidity sensor to the automatic control system. This will allow the equipment to automatically adjust parameters like the air inlet temperature and air volume.
Equipment inspection and maintenance before winter
Make sure the insulation layer is intact by thoroughly inspecting the osepa separator’s outer shell and pipelines before the start of winter. To guarantee that the equipment can function normally in a low-temperature setting, replace or add to aging insulation materials as needed.
The exhaust effect of moisture is directly impacted by the exhaust system’s smoothness. Clear the exhaust duct of any debris and obstructions, check the fan’s functioning, make sure it can effectively release moisture, and avoid moisture retention brought on by subpar exhaust.
Check temperature control devices, such as heaters and preheating systems, regularly to make sure they can function properly and support the classifier’s temperature steadily.
Reasonably adjust the inlet temperature and air volume
To lessen the chance of condensation, raise the inlet temperature appropriately so that the separator’s temperature is consistently greater than the dew point. Making timely adjustments to the inlet temperature is very crucial, especially at night and during periods of precipitous temperature reductions.
To prevent a sharp drop in temperature, keep too much cold air from entering the apparatus immediately. To prevent uneven airflow brought on by insufficient air volume, the cold air flow rate should be regulated, particularly during times of high feed.
Material humidity management
To lower the amount of moisture entering the separator and lessen the weight of condensation, dry the raw materials with a high moisture content before the grinding process.
To prevent adding moisture and raising the classifier’s humidity, if a water spray cooling operation is used during the grinding process, the amount of water sprayed should be suitably decreased, or the water spray operation should be stopped during the winter.
Regular cleaning and maintenance
Check and clean the separator’s interior regularly, paying particular attention to areas where materials are easy to hang (such as revolving blades, air inlets, and outlets). This will help prevent material buildup, which could negatively impact the equipment’s efficiency and smoothness.
Make sure that important parts, such as rotating parts and bearings, are regularly lubricated to avoid jamming or wear from inadequate lubrication at cold winter temperatures. You should also replace readily worn parts as soon as possible to lower the likelihood of failure.
To prevent clogging brought on by water buildup, make sure the condensate discharge system can release the condensate smoothly.
