Application scheme of PTC ceramic heater instead of ordinary heater in rotary drilling rig

- Sep 02, 2020-

Application scheme of PTC ceramic heater instead of ordinary heater in rotary drilling rig:


"Overview

The heaters used in YZ series and KY series rotary drills in China are mainly installed in the operation room and mechanical room of the drilling rig. The operation room is used for heating in winter. The function of the mechanical room is to keep the air compressor system warm and prevent oil condensation and poor circulation of the air compressor pipeline. When the temperature of the mechanical room is lower than 10 ℃ in winter, the start-up circuit of the air compressor is disconnected, and the air compressor is not The drilling rig can not operate normally if it is started by the method. In addition, the temperature of the machine room is too low, the oil circulation is not smooth, and the automatic lubrication system will not work normally. The heater of the machine is NFP type heater with the power of 6-7.5kw. The heating pipe of the heating part of the heater selects the ordinary nickel chromium resistance wire with heat sink as the heating body in the heating pipe. At present, some domestic toothwheel equipment and electric shovel are equipped This type of heater is used in the equipment.

PTC HEATING ELEMENT


The deficiency of using ordinary Ni Cr resistance wire as heater in rotary drilling rig

The heating pipe of NFP type ordinary heater is ordinary heating pipe with heat sink, and the heating body is nickel chromium resistance wire. At present, this kind of heater is used in drilling rig, electric shovel, and some equipment and facilities such as crushing ore and rock discharging. The heating resistance rod of NFP heater is heated by nickel chromium electric wire. The nickel chromium electric wire is easy to be damaged and has a short service life. The service life is about 3000h. The current is large at the moment of startup, which is also a kind of damage to the heating pipe. Once the fan in the heater is damaged and stopped, the heating pipe will be seriously heated and easy to be damaged. The working site of drilling rig is generally in the stope and the stope is large When the high-voltage and large motor of the electric shovel or rock discharge machine is started, the network voltage fluctuates greatly, which has a great impact on the service life of the heater. Too high network voltage will instantly burn down the heater. As long as the common heater with nichrome resistance wire is connected to the power source, it will be in a hot state. Once the heater fan is damaged, the thermal protection will fail, and the heater will heat up If the tube turns red until there is an open fire, the heating pipe will be damaged if it is not shut down in time. Meanwhile, in winter, the area near the heater is also the key fire protection area of the equipment. The fire accidents caused by heater failure often occur on the equipment, and the loss degree is related to the timely and untimely discovery time. If it is not found in time, it will be serious If the installed capacity of each drilling rig is 4, and the installed capacity of electric shovel is 8, if the power of heater is increased, the high-power heater shovel also needs to be equipped with 3-4 sets. A medium-sized mine needs to be equipped with 5-8 rigs, and the matching shovel is calculated as 5-8, even if other operations The demand for equipment in the area is ignored, and hundreds of heaters need to be replaced every year. The configuration of a large mine has to be multiplied by multiple. Because the voltage fluctuation of stope network is generally large, the heater damage mainly includes heating pipe and blower motor. Maintenance personnel have a large amount of daily maintenance and repair, and the equipment cannot be started at low temperature due to heater damage in winter, The increase of shutdown hours will affect the efficiency of machine operation, affect the mine production, and even freeze the equipment in serious cases. Therefore, it is necessary to update the heater.


Feasibility analysis of using PTC ceramic heating plate hot air heater drill

PTC heater, also known as PTC heater, is composed of PTC ceramic heating element and aluminum tube. This type of PTC heater has the advantages of small thermal resistance and high heat exchange efficiency. It is an automatic constant temperature and power saving electric heater. The outstanding feature is the safety performance. Under any application situation, it will not produce the phenomenon of "reddening" on the surface of the electric heating pipe heater, which avoids the potential safety hazards such as scald and fire. The PTC ceramic heater is a kind of thermistor. Because of the temperature characteristic of PTC element, the element can adjust its resistance automatically according to its own temperature. When the resistance of the heater changes, the output power will change naturally, which is the first qualitative one Leap. Therefore, PTC heater composed of PTC elements can automatically adjust heating power without other control equipment. In this way, when the air compressor system is in normal operation, the heater automatically adjusts the power according to the actual situation of the mechanical room, and even stops the machine, reducing unnecessary waste and never overheating, which is economical, energy-saving and efficient. When the fan in the heater stops running in case of fan failure, the power of PTC heater will automatically drop sharply due to insufficient heat dissipation. At this time, the surface temperature of the heater is maintained at about Curie temperature (generally around 250 ℃), so as to avoid the phenomenon of "reddening" on the surface of electric heating pipe heater. Moreover, PTC elements do not glow red and open fire when they work, which not only ensures the safety of the whole equipment, but also reduces unnecessary heat loss. Due to its semiconductor characteristics, PTC ceramic heater completely eliminates the occurrence of fire accidents and has excellent safety characteristics, which is the second qualitative leap. The effect of ordinary heater on vibration and earthquake resistance is general in heating state, and it is used in fixed workshop

Some, the stope equipment in the operation and production and equipment movement, the vibration is big, the old heater is very easy to be damaged, the inspection and maintenance workload increases, the maintenance vehicle frequency increases, at the same time will bring certain influence to the production. The PTC ceramic heating plate used in PTC ceramic heater is thermistor, which has excellent seismic resistance, which is the third qualitative leap. The service life of PTC components is more than 10000h, and the service life of ordinary heater is 3000h. After a winter use, the service life is basically reached, which is not included in the daily use process because of network voltage fluctuation, equipment vibration, damage, replacement and maintenance quantity.

The service life of PTC ceramic heater is much longer than that of resistance wire heater, which is more than 3 times. Because PTC heater has a wide range of voltage adaptability, it can design the working voltage at 12 ~ 380V according to the needs: when the working voltage changes twice, the surface temperature changes very little, so it will not affect the power output because of the power supply voltage fluctuation. The daily use is more stable and reliable, and the failure rate is extremely low, which is its fourth qualitative leap. The price of the new heater is about 150% of the price of the ordinary heater, and the initial cost of technology replacement has increased, but after a service cycle, the economic benefits are undoubtedly improved; at the same time, the vehicle and labor costs during maintenance are reduced.

It is imperative to update the heater. Just like the original lighting industry, from ordinary incandescent lamps to fluorescent lamps to energy-saving lamps and now to LED lighting, the price of energy-saving lamps and LED lamps is higher than that of incandescent bulbs. However, along the way, people have fully accepted energy-saving lamps and lanterns because they are more energy-saving, efficient, long-lived and environmental protection. Therefore, it is hoped that domestic manufacturers can gradually eliminate the old heaters. If the NFP type heaters used in domestic drilling rigs, electric shovels, ore crushing, rock dumping, workshops and other equipment and facilities are updated, replaced and upgraded to PTC ceramic heaters, the purchase cost of heater spare parts can be saved: the cost of the first year is 150% of the original winter heater cost. Due to less damage, there is almost no heater in the second year In the third year and the fourth year (and so on), 9 / 10 of the total amount of spare parts declared in winter can be reduced. In addition, the more important point is to reduce the workload of electrical maintenance personnel in daily maintenance of heaters, improve the safety and reliability of heaters, and minimize the safety risks. The direct benefits, indirect benefits and safety benefits are huge.