Common lifting tasks in power plants

The lifting needs of power plants are very clear, all around the installation and maintenance of core equipment to start, there is no extra miscellaneous work. The most common is the generator stator lifting, which is also one of the most demanding tasks for cranes.

In addition to the stator, turbine rotor handling is also a core task, turbine lifting crane (turbine lifting crane) needs to accurately control the strength and angle, to avoid damage to the rotor's precision structure. In addition, overhead cranes are indispensable for the maintenance and lifting of valves and pumps, as well as for the installation of heavy equipment in new power plants.

These tasks may seem infrequent, but each time is related to the normal operation of the power plant, no room for error. Especially large generator components, often require extremely high lifting capacity and coordinated lifting capacity, which is the core difference between power plant cranes and ordinary workshop cranes.

The core characteristics of power plant lifting loads

Power plant lifting load, and the load of the ordinary industrial scene is completely different, three characteristics are particularly prominent, but also the key basis for selection.

Second is the high value, whether it is the generator stator, turbine rotor, or other core components, the cost is extremely high, once the lifting process of bumping, damage, maintenance costs are staggering, and may even affect the power supply of the entire power plant.

Finally, the positioning accuracy requirements are extremely high, especially the stator, rotor installation, the coaxiality, perpendicularity of the deviation requirements of 0.1mm or less, a slight deviation may lead to equipment cannot operate normally, which requires the crane has accurate positioning capabilities.

Lifting capacity (the core of the core)

Many power plants will choose the main and sub-hook configuration of the crane, the main hook is used to lift heavy parts, such as the stator, rotor; sub-hook is used to lift light parts, such as valves, pumps, so as to meet the needs of different loads, but also to improve operational efficiency.

There are many scenarios that require synchronized lifting of two machines, for example, when the load exceeds the carrying capacity of a single crane, as in the Jinchang Peak Coal Power Project, with two cranes working together, which requires cranes to have synchronized control to ensure that the two sets of equipment movements are consistent, to avoid tilting of the load.

Span and Coverage

Power plant turbine halls are usually very large, the span of the crane must be able to cover the entire turbine hall, to ensure that all maintenance areas can be reached, there is no operational blind spot.

If the span is small, it will lead to part of the area cannot be lifted, such as the turbine components on both sides, can only be frequently adjusted to the position of the equipment, which is time-consuming and increases the risk of safety; choose a large span, it will increase the manufacturing cost of the equipment, and the stability of the operation will be affected, the need for accurate accounting.

Lifting height

The choice of lifting height mainly depends on two aspects: one is the height of the turbine and generator, and the other is the vertical dismantling requirement during operation.

The core equipment of the power plant is relatively tall, the lifting height of the crane must be sufficient to lift the heavy components vertically, but also reserve enough space for dismantling to avoid collision with the equipment and the roof during lifting.

Accuracy requirements

The lifting operation of the power plant requires much higher precision than the common scene. Especially for the installation of generator stator and turbine rotor, the slightest deviation may lead to serious consequences.

This requires cranes to have high-precision positioning capability, and it is recommended to equip with an anti-sway system. For example, in the case of dual-machine cooperative lifting, the height difference of each lifting point is monitored in real time by a laser range finder, so that the tilt is controlled within the design permissible range (usually no more than 1/1000), and load swaying is avoided.

For overhead crane for generator maintenance, precise positioning is even more essential to minimize bumps during installation and protect high-value components.

Double girder overhead crane (most recommended)

In power plant maintenance, double girder overhead crane is the absolute mainstream, and it is also the most often recommended model by Henan Mine Crane. It is indispensable for almost all core lifting tasks in power plants.

Single girder overhead crane (auxiliary use only)

Single girder overhead crane can also be seen in power plants, but the use of the scene is very limited, and can only be used for auxiliary maintenance operations.

Dual/linked lifting system

When the lifting load exceeds the carrying capacity of a single crane, it is necessary to use the dual-machine linkage lifting system, which is very common in large power plants.

Unique working characteristics of power plant cranes

The working mode of power plant cranes is very special and completely different from that of ordinary workshop cranes: low frequency of use, but high load intensity, and extremely high reliability requirements.

From the point of view of working class, power plant cranes usually belong to ISO A3-A5 class, because the frequency of use is not high, unlike workshop cranes that operate continuously every day. However, this does not mean that you can choose low-specification equipment, on the contrary, because of the extreme loads to be subjected to, the specifications and quality of the equipment must be up to standard.

Many customers will fall into a misunderstanding: “Since it is used less, just choose cheaper and lower specifications.” This idea is very dangerous, power plant lifting operations, a failure may lead to power plant shutdown, the loss is much higher than the difference in the price of the crane.

For example, Liu Jiaxia Hydropower Plant crane, although the number of annual use is not much, but each time to lift hundreds of tons of heavy components, low-specification equipment simply cannot withstand this load, long-term use is also prone to failure, affecting the normal operation and maintenance of the power plant.

Frequency of use and model matching

Although the frequency of use of power plant cranes is low, but there are differences in the frequency of use of different power plants, the selection of models should also be combined with the actual situation.

For large power plants, the number of units, the number of annual maintenance is relatively high, it is recommended to choose A5 class double girder overhead crane, stability and durability is better, and can adapt to the relatively frequent high-load operations; for small power plants, the number of maintenance is small, you can choose A3-A4 class double girder cranes, which meets the demand, but also can reasonably control the cost.

Regardless of the frequency of use, the core principle is: do not look at the frequency of use, but only look at the load strength and reliability, would rather have a slightly higher specification, cannot be forced to use low-specification equipment.

Anti-sway technology

Anti-sway technology is not optional but mandatory for power plant cranes. Especially when lifting turbine rotors, generator stators and other high-value, high-precision components, once swaying, it may cause damage to the components.

Henan Mine Crane's power plant cranes are equipped with an anti-swaying system, which can automatically adjust the crane's operating speed and direction through real-time monitoring of the swaying amplitude of the load, so as to control the swaying in the smallest possible range and ensure a smooth lifting process.

In the case of dual-machine cooperative lifting, the anti-sway technology can also be used with synchronized control to avoid load tilting caused by inconsistent movements of the two cranes, which further improves the safety and precision of lifting.

Variable frequency speed control (VFD)

Variable frequency speed control (VFD) is the core technology to realize precise positioning, and is also the recommended configuration for power plant cranes. Ordinary single-speed speed control is not smooth enough for starting and stopping, which easily leads to load shaking and cannot meet the precision requirements of the power plant.

Variable frequency speed control can realize smooth start and stop, accurately control the crane's lifting and running speeds, and even realize millimeter-level positioning, which is crucial for the installation of generator stators and turbine rotors.

For example, in the stator installation, the stator needs to be accurately placed into the machine base, and the frequency conversion speed control enables the crane to move slowly and smoothly, avoiding knocking caused by excessive speed and ensuring that the installation accuracy meets the requirements.

Synchronized control (advanced configuration)

Synchronization control is mainly used for double machine linkage lifting, which is a necessary configuration for lifting heavy parts in large power plants. Without synchronized control, the movements of the two cranes cannot be consistent, it is easy to load tilt, shaking, and even cause safety accidents.

Our Henan Mine Crane's synchronization control system adopts the master-slave control mode, setting one crane as the master and the other as the slave, with the slave's rotational speed and torque completely following the master, and at the same time with real-time encoder monitoring to ensure that the two devices are synchronized in their movements.

In addition, the system also has a torque following function, when one side of the crane encounters increased resistance, it will automatically increase the torque to maintain the same speed, avoiding runout due to uneven loads, and ensuring the balance of the lifting.

Required safety devices

The safety requirements of power plant cranes are much stricter than those of ordinary industrial cranes. The following safety devices are indispensable and directly related to the safety of operators and equipment.

Overload protection is the basis to prevent the crane from carrying more than the rated load, to avoid equipment damage and safety accidents; double braking system, can be quickly braked in case of emergencies, to ensure that the load is stable, even if a set of braking system failures, the other set can also work normally.

Emergency stop button, in any position can quickly stop the equipment, to cope with unexpected situations, such as load shaking, equipment failure; limit switches, including lifting height limit and running stroke limit, can prevent the crane from exceeding the operating range, colliding with the equipment or building.

Our Henan Mine Crane power plant cranes, all safety devices comply with international standards, and will undergo strict quality testing to ensure that every component works properly for power plant lifting operations.

The importance of inspection and maintenance

Power plant cranes are used infrequently, but regular overhaul and maintenance still cannot be ignored. Many failures are caused by long-term non-maintenance, resulting in aging and wear and tear of components.

Daily inspection should focus on the wire rope, hook, braking system and other core components, to see if there is wear and tear, corrosion; regular maintenance should be carried out in accordance with the standards, such as the Liu Jiaxia Hydropower Plant, will take advantage of the unit overhaul window, the crane for a comprehensive overhaul, and after the completion of the overhaul, but also to carry out the load test, to ensure that the performance of the equipment is up to standard.

It is important to know that crane failure in maintenance operations means power plant downtime and huge losses. Good preventive maintenance can effectively avoid failures, extend the service life of the equipment, and ensure that the crane can work properly when needed.

Integration with turbine hall design

When building a new power plant, the installation of cranes should be synchronized with the design of the turbine hall, and should not wait until the plant is built before considering the cranes, otherwise it is easy to have adaptation problems.

Crane track arrangement, support structure, and turbine hall equipment layout, building structure to match, to ensure that the running track of the crane can cover all maintenance areas, while not affecting the normal operation of other equipment.

We, Henan Mine Crane, will arrange professional engineers to cooperate with the architectural engineers and equipment engineers of the power plant to integrate the design of the crane into the plant design, to avoid the trouble of later modification, optimize the use of space and reduce the installation cost.

Wheel load and structural load

The load of the power plant crane is very large, the wheel load and structural load on the plant building is also a great impact, must be verified by professional engineering to ensure that the plant can withstand the crane load.

Especially large double girder overhead cranes with large wheel loads need to be reinforced on the track beams and columns of the plant building to avoid damage to the building structure at a later stage. If this is ignored, the crane may not be able to operate normally after installation, and may even cause safety accidents.

When selecting cranes, Henan Mine Crane will first survey the structure of the power plant and calculate the load-bearing capacity, and then design a suitable crane program according to the actual situation to ensure that the wheel load and structural loads meet the load-bearing requirements of the plant.

Cost Composition (CAPEX + OPEX)

When many power plants purchase cranes, they only focus on the initial purchase price, which is a big misunderstanding. The total cost of the crane, including the initial investment (CAPEX) and operating costs (OPEX) two parts, need to be comprehensive accounting.

Initial investment includes the price of the crane equipment itself, transportation costs, installation and commissioning costs, as well as the cost of reinforcement of the plant structure; operating costs include routine maintenance costs, spare parts replacement costs, maintenance costs, energy consumption and so on.

Henan Mine Crane will list all the costs in detail when giving the quotation to the customer, help the customer to account for the whole life cycle cost, avoid the hidden cost in the later stage, so that the customer is clear about what each sum of money is spent on.

Core knowledge: reliability is more important than cost

Power plant downtime costs are extremely high, a unit grounded for a day, the loss may be as high as hundreds of thousands of dollars, or even millions of dollars. The poor quality crane, although the initial price is cheap, but the quality is unreliable, prone to failure, resulting in downtime, this part of the loss is much higher than the difference in the price of the crane.

Our Henan Mine Crane's power plant cranes, although the initial investment is a little higher than the small manufacturers, but the use of high-quality components, such as high-strength steel, high-quality steel wire ropes, reliable braking system, low maintenance frequency, the spare parts are supplied globally, and can be quickly replaced to reduce downtime.

Moreover, our equipment consumes less energy and saves a lot of energy costs in the long run. For power plants, choosing a reliable crane may seem to invest a little more upfront, but in the long run, it is more cost-effective to avoid downtime losses.

Combined with these years of experience, I summarized a few customers are most likely to step on the pit, we must avoid when selecting the type, you can take a lot less detours.

The most common is that “low frequency = low specification”, many customers feel that the crane is used less, choose cheap, low specification equipment, the result is that when lifting heavy parts, either cannot carry, or failure, the loss is not worth it.

Neglecting the need for dual-machine lifting is also a common misconception. Some power plants did not take into account the lifting needs of large stators in the early stage, only the procurement of a single crane, the later need to lift heavy parts, can only temporarily increase the equipment, not only increase the cost, but also affect the maintenance schedule.

When selecting a model against this list, you can quickly clarify the needs, avoid missing key parameters, save selection time, and ensure that the right equipment is selected:

✔ Maximum lifting weight (weight of generator/turbine components with spreader)

✔ Span of the turbine hall (to the nearest centimeter)

✔ Whether double machine linkage lifting is required

✔ Lifting accuracy requirements (e.g. accuracy of stator and rotor installation)

✔ Working level (combined with frequency of use and load intensity)

What type of cranes are typically used in power plants?

Mostly double girder overhead cranes, which is a standard model for power plant maintenance, with high load capacity and good stability to meet the lifting needs of heavy components, such as Liu Jiaxia Hydroelectric Power Plant and Jinchang Peaking Coal and Power Project, are using double girder overhead cranes.

Why do power plants use two cranes?

Mainly for the safe lifting of heavy components such as large generator stators. When the load exceeds the carrying capacity of a single crane, two cranes are required to work together to ensure even load distribution and smooth lifting through a synchronized control system.

Power plant cranes need high working level?

“Low frequency” does not mean “low specification”, reliability and load carrying capacity is the core.