Application of Screw Air Compressors in Coal Mine

Air compressor W is an important equipment for coal mine production. Currently, there are many types of air compressors in common use, and most of them are compound piston type air compressors. Screw air compressors, whether in terms of performance or in terms of application, have high efficiency advantages, however, at the present time, thorough application is not realized. The influencing factors are mainly due to the lower cost of the former and the high economic cost of the latter, as well as the lack of corresponding empirical and theoretical basis for guidance. So, for the screw air compressor in the field of coal mining application to analyze, fully clear application of the key points and fault handling measures, etc., can provide a certain theoretical basis for the application of screw air compressor.

1. Screw air compressor development analysis

Screw air compressor in the world has a certain history of development, as early as the 20th century in Europe, a country has screw air compressor first put into production, by the 30s began to apply, until the 50s has evolved into a large-scale application. Screw air compressor type is relatively single, only single screw and twin screw two kinds. In recent years, with the improvement of the effectiveness of the application of screw air compressors, in the field of coal mining has been gradually well received and sought after, screw air compressor application scale and frequency is also gradually expanding.

(1) Structure and working principle analysis

The internal structure of the screw air compressor is more complex, mainly containing the motor, host, filter element, and road pipe, oil filter and oil cooler. Through the mechanical movement, the resulting working principle is mainly to suck air into the air compressor, close the studio, the space compression, thus increasing the pressure of the studio, in order to meet certain parameters after lifting the discharge system, the gas will be released in the exhaust pipe.After being processed by the screw air compressor, the air can be compressed to the required value and applied in the operation. Screw air compressors have the advantages of precision and science, and can meet various operational requirements in the application, so they are widely welcomed by coal mine applications.

(2) Analysis of performance characteristics

Compared with the traditional compound piston air compressor, the advantages of this novel air compressor are mainly reflected in the performance and stability, efficiency and other aspects. With the progress of scientific and technological innovation in a country, the screw air compressor structure design in the also continue to improve, through research and innovation, launched a number of representative product types, such as common GHH, XP, X and other models, according to the performance of the distinction, can be divided into permanent magnetism, integrated, oil-free screw air compressor, etc., in the application of both efficiency and performance, have a more obvious advantages. Overall, the performance of the screw air compressor is mainly reflected in: against the harsh operating environment of the coal mine, and strong adaptability. For the disturbing factors, can ensure efficiency on the basis of the environment without interference. The exhaust volume is stable and not disturbed by air pressure. The studio is stable and not disturbed by the number of revolutions. Continuous high-intensity operation, uninterrupted inhalation and delivery of gas, regulating the high and low values of air pressure pulsation, no dependence on the gas tank.

2. Screw air compressor system composition and features

(1) System Composition

Screw air compressor system is composed of control system and station monitoring system, the main role of the control system, according to the specific situation, human operation, specific parameters and other relevant conditions through the instructions given to the system for control. The control system consists of the display of the operating parameters, as well as the values of the exhaust temperature and pressure of the unit, the value of the pressure before separation, and the adjustment of the operating parameters of the workshop.And the station monitoring system is divided into two modules: software and hardware. Hardware system contains: industrial control machine, printer, monitor, and safety valves, pressure gauges and other hardware equipment. The software system contains: login rights, equipment control, parameter detection, fault signal warning and so on.

(2) Characteristics

The main features of screw air compressor are high efficiency, energy saving and stability. The forced air delivery of screw air compressor has more obvious characteristics, and there is no great correlation between the exhaust volume and the exhaust pressure, so there is no problem of mutual influence. A 1MPa increase or decrease in exhaust pressure will reduce or increase the exhaust volume by 1%. At the same time, its internal pressure ratio is not strongly correlated with the rotational speed, and the ratio of internal pressure presents a constant value under any rotational speed condition.

The screw type is not excessively affected by the conditions of discharge volume, discharge pressure and speed, but on the contrary produces not much variation, and the values can be controlled in a high range, less than the power variation. Because of the high rotational speed of the compressor and the lack of a speed reduction system, the gas delivery is continuous, with relatively low pulsation, and if there are no special requirements, it is possible to dispense with the installation of a gas tank.

3. Screw air compressor working fault principle analysis

Although the screw air compressor is a new type of equipment in the field of coal mine, which can promote the development of coal mine modernization, but in view of the current situation, there are many interference and failure factors, which affect the normal operation of the equipment and can not provide adequate operating conditions for coal mine production. Therefore, the analysis of the failure principle, from the source to clarify the failure factors, for the application of screw air compressor in the field of coal mining has a substantial role.

(1) High-temperature shutdowns

The main influencing factors of high temperature shutdown are: insufficiency of cooling oil, high overall temperature of the surrounding environment, poor electrical connectors, and the working effect of the cooling system cannot meet the requirements. In the face of this problem, it is recommended that the staff combined with the surrounding operating environment to establish an accurate assessment of the equipment, improve the current ventilation conditions, check the cooling system, sampling of cooling oil, and professional testing, to ensure that the parameters are qualified, there are no impurities, to avoid problems with the equipment, and the air compressor between the connecting lines are fully inspected to ensure that the contact is in a good condition.

(2) Automatic shutdowns

The main reasons for automatic shutdown can be divided into two kinds, one is the shutdown caused by high pressure, and the other is the automatic shutdown caused by motor overload. Motor overload caused by automatic shutdown, the main reason is that the current is too large, which leads to overheating of the power line, triggering the protection mechanism of the motor equipment, thus triggering a trip shutdown. Combined with the actual situation, the specific solution strategy, the need for timely detection of the power supply voltage value, and ensure that the value is within the normal range.

The automatic shutdown of the equipment triggered by high pressure is mainly due to the closure of the isolation gate, which affects the normal operation of the exhaust system, thus leading to low system operating efficiency and triggering the shutdown. In the face of this problem, the common solution strategy is to troubleshoot the electromagnetic gate failure, timely disassembly and cleaning of the electromagnetic gate, to avoid affecting normal operation.

(3) Low pressure value

The main reason for the low pressure value is that the air volume is too low, which triggers the malfunction due to the low jump design pressure value. The solution is to check the workshop to ensure that there are no leaks in the operating system and to set the jump pressure value in time.

(4) Abnormal power indicator light

In the case of unreasonable voltage control, there will be power indicator abnormalities, maintenance personnel must focus on the inspection of power controllers, during the inspection should uphold a meticulous and comprehensive attitude, and repeatedly observe the secondary control group, check whether there is a fused wire problem.

(5) Air compressor not loading

If the air inlet valve is not opened successfully, it will lead to the unloading phenomenon of the air compressor. To solve this problem, the first task is to cut off the power system of the air compressor, followed by troubleshooting the air inlet valve in the air compressor system, and then troubleshooting whether the internal stand-alone machine produces a fault.

4. Screw air compressor in the actual use of the problems and improve the measures

(1) Existence of relevant problems

When the Air Compressors filter is clogged, the filter element is not replaced at the first time, which reduces the processing capacity of the filter and makes it unable to meet the standard requirements. On the one hand, as the operation continues, the air compressor will gradually reduce the volume of exhaust, which ultimately leads to a reduction in the pressure, resulting in the supply of air system is not ideal; on the other hand, the failure will result in a large amount of wastage of electrical energy, materials, and so on.

The original equipment in the shutdown state, stay in the after-cooler parts of the hot oil will flow again to the oil separator, reducing the actual service life of the oil separator, prompting the oil separator to increase the probability of replacement and maintenance. At the same time, the original gas line has a long connection line, its protection device because of the influence of the distance factor often occurs signal distortion and action lag phenomenon, affecting the effectiveness of the protection device to play a full range of performance.

Because from the router to the host often use the steel wire hose as a return pipe, while the oil filter equipment outlet and the host components of the oil return port does not maintain the same height, and because of the length of the steel wire hose, the host location and connecting pipeline and other factors, resulting in the host in a state of shutdown, the steel wire hose and the bottom of the host contact phenomenon, so if the host began to run again, it will be because of the vibration of the host as well as the liquid oil If the host starts to run again, the vibration of the host and the oil flow factors, resulting in steel wire hose and chassis friction, because this friction phenomenon will not be easily detected by the maintenance personnel, leading to the steel wire hose is very easy to break the problem, resulting in a large number of oil sprayed out, the occurrence of unnecessary failures.

(2) Improvement measures

In order to prevent the Air Compressors filter from clogging, on the level of the original air filter element, it is necessary to add a more comprehensive air filtration system, with the help of industrial non-woven fabrics W, which are designed in the shape of a pocket and attached to the outside of the filter element, responsible for the primary filtration of the air, and the cleaning work is completed on a regular basis every month to remove the dust from the clean air flow in the roadway, and if the dust is large, it can be processed with the help of clean water, which is a very simple way, with a relatively low cost of manufacturing, and is easy to clean up.In addition, in order to ensure the timely replacement of the filter element components, the air filter installed on the vacuum indicator, combined with the vacuum indicator inside the display of the colour of the pigment to determine the status of the filter element, when the colour shows red, it means that the filter element needs to be replaced, so as to prevent the replacement of the filter element lagging behind the problem of low oil quality.

In order to increase the actual service life of the oil separator and reduce the overall cost of its maintenance and replacement, the oil separator components and the after-cooling device can be equipped with an oil cut-off check valve in the main oil return pipeline, which ensures that the compressor is in a state of shutdown, so that the oil does not flow to the oil separator again, so that the oil separator improves the safety and reliability, and increases the life of the oil separator; and at the same time, in order to prevent failure of the protection device. At the same time, in order to prevent the failure of the protection device, centralized installation of air volume control valve group, will be arranged at the top of the side of the host, the position and the host to maintain the shortest distance, in this state the control signal has a smaller transmission distance, there will be no distortion or lag in the transmission period, which ensures that the protection device has a more secure and reliable action.

In order to improve the main oil return line friction spraying problems, the initial soft connection upgraded to a hard link, specifically, upgraded the steel wire hose to a seamless steel pipe, special attention needs to be paid to put into use before the steel pipe must be comprehensively cleaned, hydrochloride acid as the main cleaning fluid, to prevent the steel pipe inside the adhesion of iron filings or rust and other substances are mixed with lubricating oil, reduce the overall quality of the lubricating oil, and at the same time in the connection period, the probability of the use of right-angled elbow as far as possible should be reduced to ensure that the connecting pipeline with a strong degree of smoothness, which reduces the waste of the oil during the cycle of the oil, as well as on the cycle to bring about the impact of the oil.

5. Application of screw air compressor in coal mine production

(1) Applications in economic energy conservation

Compared with the screw air compressor, the traditional piston air compressor has more advantages in cost, and it has been used for a long time in the field of coal mine, so everyone is more familiar with its operation. Screw air compressor in coal mine production is more expensive, and has certain requirements on operation technology, need to train people who can operate it skillfully. But from a long-term point of view, the screw air compressor has the advantage of efficiency, is the traditional air compressor can not be replaced, screw air compressor for coal mine production is not only the efficiency of the promotion, or economic benefits. Therefore, most of the coal mines in a certain country have begun to apply screw air compressors on a large scale.

In specific production, the common screw air compressor is mainly divided into two kinds, single screw and twin screw. Whether in the performance comparison, or economic considerations, do not need lubricating oil screw air compressor obviously has a stronger advantage, mainly reflected in the maintenance work is relatively simple, low noise and so on.

(2) Applications in improving efficiency

Comprehensive protection ability is the more outstanding advantage of screw air compressor. Timely face unloading delay and stop, as well as the main motor overload shutdown and other issues, will not have a greater impact on the screw air compressor, it is difficult to occur a large failure, will not produce too much maintenance costs. At the same time, the chiller because of the thermostatic valve automatic control unit, set the fan cooling function in the cold air unit, can greatly reduce the possibility of failure. Screw air compressor because it belongs to the full computer automatic control type system, through the computer PLC, as well as IMMI to build the human-machine interface, through the human-machine dialogue as well as the system display, you can complete the operation.

(3) Stronger environmental design capabilities

Screw air compressor mainly adopts soundproof box design and contains compact and complete unit, which has the advantages of smaller volume, lighter deadweight and small footprint, and does not need special foundation design to achieve convenient installation and construction. The screw air compressor can be completely balanced in its work, which not only promotes the normal operation of the system, but also provides a balanced and stable running condition for the machine. So the screw air compressor does not need to place the foundation, only need to find a flat and ventilated location, can enter the work, this advantage is very meaningful for the coal mine production with low operating difficulty.

6. Maintenance points of screw air compressor

In the coal mine machinery and equipment put into use during the strict implementation of routine maintenance work, its operation plays an important role in safeguarding, screw air compressor is no exception. The daily maintenance of screw air compressor mainly focuses on the air inlet filter element, oil filter and oil fine separator and other related parts. Among them, the specific function of the air inlet filter element is to filter through the unavoidable dirt and dust particles in the air, to promote the screw from the compression chamber to have clean air input, to prevent equipment damage. Due to the screw machine parts gap can only complete 15μm particles of filtration work, if the filter element is broken or clogging phenomenon, will lead to a large number of more than 15μm particles flow into the air compressor circulatory system, thereby reducing the specific life of the oil filter element and oil separator. Therefore, maintenance personnel need to carry out regular maintenance and cleaning of air filters, and replace the parts at the first time when damage occurs.

Conclusion

Screw air compressor is the key machinery applied in the current coal mining field, compared with the traditional piston air compressor, screw air compressor has the advantages of high performance, high efficiency, high quality and so on, and is stronger than the piston air compressor both in terms of economic benefits and system operation. At the same time, screw air compressor in the appearance and environmental protection, automation and other aspects of other air compressors are irreplaceable, for China’s coal industry to provide the best production help.