Method of operating a mineral material processing plant

Abstract

A method of operating a mobile mineral material processing plant, comprising estimating power needed for operating the mobile mineral material processing plant; selecting an operating point for a motor and a generator driven therewith based on the estimated power; adjusting motor speed in response to the selected operating point; generating AC power with the generator; rectifying the generated AC voltage into DC voltage; and converting the DC voltage into AC voltage with at least one inverter element in order to drive at least one electric motor connected thereto in accordance with the requirements of the mineral material processing device driven with said electric motor

Description

[0001] METHOD OF OPERATING A MINERAL MATERIAL PROCESSING PLANT

[0002] TECHNICAL FIELD

[0003] The present disclosure generally relates to a mobile mineral material processing plant and a method of operating a mineral material processing plant. The disclosure relates particularly, though not exclusively, to a mobile mineral material processing plan with an electric drive. The disclosure relates particularly, though not exclusively, to a mobile mineral material processing plant with optimized power generation

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] Mineral material processing, in particular mobile mineral material processing, is increasingly moving towards electric and hybrid power generation. In hybrid power generation, a generator is driven with a motor, for example a diesel motor.

[0007] Typically, the motor is scaled in such a way that there is extra capacity available, which may lead to situations in which the motor is not operated at an optimal, or preferable, operating point. It might for example be that the motor is more often than not operated at too low rpm. Furthermore, the motor may every now and then need to be operated at specific rpm range due to for example exhaust gas purification regeneration.

[0008] Accordingly, the present disclosure aims to enable power generation for the mineral material processing plant independent on the running speed of the motor so that the motor operates at a preferred, or even optimal, operating point in an energy efficient manner.

[0009] SUMMARY

[0010] The appended claims define the scope of protection. Any examples and technical descriptions of apparatuses, products and / or methods in the description and / or drawings not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

[0011] According to a first example aspect there is provided a method of operating a mobile mineral material processing plant, comprising estimating power needed for operating the mobile mineral material processing plant; selecting an operating point for a motor and a generator driven therewith based on the estimated power; adjusting motor speed in response to the selected operating point; generating AC power with the generator; rectifying the generated AC voltage into DC voltage; and converting the DC voltage into AC voltage with at least one inverter element in order to drive at least one electric motor connected thereto in accordance with the requirements of the mineral material processing device driven with said electric motor.

[0012] Estimating the power needed for operating the mobile mineral material processing plant may comprise estimating the maximum power needed.

[0013] Selecting an operating point for the motor and the generator driven therewith based on the estimated power may comprise selecting an operating point in which the estimated power needed is generated at a rotating speed of the motor that is fuel efficient and in the preferable operating speed range of the motor.

[0014] Generating AC power with the generator may comprise generating AC power with a predetermined voltage and with a frequency dependent on the rotating speed of the motor at the selected operating point.

[0015] Estimating the power needed for operating the mobile mineral material processing plant may comprise estimating a power desired for charging, or discharging, an energy storage element.

[0016] Selecting an operating point for a motor and a generator driven therewith may comprise selecting an operating point based on rotating speed of the motor required for maintenance.

[0017] According to a second example aspect there is provided a mobile mineral material processing plant, comprising a motor; a generator driven with the motor; a rectifier element; at least one inverter element; at least one electric motor connected to the at least one inverter element for driving at least one mineral material processing device; and a control element configured to cause operating the mobile mineral material processing plant according to the method of the first example aspect.

[0018] The at least one mineral material processing device may comprise a crusher, a feeder, a conveyor, a crawler track drive, a material air blower, a hydraulic pump or a screen.

[0019] Different non-binding example aspects and embodiments have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

[0020] BRIEF DESCRIPTION OF THE FIGURES

[0021] Some example embodiments will be described with reference to the accompanying figures, in which:

[0022] Fig. 1 schematically shows a block view of a mineral material processing plant according to an example embodiment;

[0023] Fig. 2 shows a flow chart of a method according to an example embodiment; and

[0024] Fig. 3 shows an example power and consumption curve of a motor and generator in an example embodiment.

[0025] DETAILED DESCRIPTION

[0026] In the following description, like reference signs denote like elements or steps.

[0027] Fig. 1 schematically shows a block view of a mineral material processing plant 100 according to an example embodiment. In an example embodiment, the mineral material processing plant comprises a mobile processing plant. In a further example embodiment, the mineral material processing plant comprises a combination of more than one mobile unit, such as a mobile crushing plant and a mobile screen.

[0028] The mineral material processing plant 100 comprises mineral material processing devices 110,120,130 that are driven by electric motors (not shown). In an example embodiment, the mineral material processing device 110 comprises the main actuator of the plant, such as a crusher or a screen. In an example embodiment, the processing device 120 comprises a conveyor. In an example embodiment, the processing device 130 comprises a further device driven by an electric motor, e.g. a feeder or a hydraulic pump for driving the feeder or any other hydraulically operated processing device. While Fig. 1 shows three processing devices 110,120,130, the mineral material processing plant 100 comprises, in an example embodiment, further devices driven by electric motor or motors.

[0029] Fig. 1 schematically shows the power distribution of the mineral material processing plant 100. The mineral material processing plant 100 comprises a generator 150 for generating electric power. The generator 150 is driven by a motor 140. In an example embodiment, the motor 140 comprises a diesel motor. The generator 150 and the motor 140 are configured to be adjusted. In an example embodiment, the running sped of the motor 140 is configured to be adjusted and accordingly the frequency of the alternating current and voltage of the generator changes. In an example, the generator frequency is adjusted between 45 and 65 Hz corresponding to a motor running speed range of 1350 to 1950 rpm. It is to be noted that the frequency range and the motor running speed range depend on the type of the motor and the generator. In an example embodiment, the voltage generated by the generator 150 remains unchanged.

[0030] The mineral material processing plant 100 further comprises a rectifier element 160 configured to convert the AC power generated by the generator 150 into DC power. In an example the generator 150 generates an alternating voltage of 400 V and the rectifier 160 is configured to provide a DC voltage of 550 V.

[0031] The mineral material processing plant further comprises an energy storage element 180 configured to store energy generated by the generator 150 and to provide stored energy for driving the processing devices 110,120,130

[0032] The mineral material processing plant further comprises at least one inverter element 170a- c. In an example embodiment, the mineral material processing plant comprises an inverter element 170a-c for each electric motor used to drive the processing devices 110,120,130. In a further example embodiment, an inverter element 170a-c is connected to several electric motors.

[0033] The at least one inverter element 170a-c is configured to convert the DC voltage from the rectifier 160, or from the energy storage 180, into AC voltage to drive the electric motor or motors connected thereto. In an example embodiment, the at least one inverter 170a-c is configured to be adjustable, i.e. the output frequency is adjusted in accordance with the desired speed of the electric motor the energy is provided for. In an example, the at least one inverter element 170a-c converts the DC voltage of 550 V into AC voltage of 0 to 400 V with a frequency of 0 to 200 Hz depending on the requirements of the electric motor being driven.

[0034] The mineral material processing plant 100 further comprises a control element 190 configured to control the various parts of the mineral material processing plant. In an example embodiment, the control element is configured to control the power generation and distribution of the mineral material processing plant 100.

[0035] Fig. 2 shows a flow chart of a method according to an example embodiment.

[0036] At step 210, the power requirements for operating the mineral material processing plant are estimated. In an example embodiment, the power requirement is estimated based on historical maximum power requirement of the mineral material processing plant. In a further example embodiment, the power requirement is estimated based on information concerning the mineral material to be processed, for example on the type of material and the processing devices needed for processing and therefrom derived maximum power needed. In a still further example embodiment, the power requirement is estimated based on the desired power for charging or discharging an energy storage element.

[0037] At step 220, an operating point is selected for power generation, i.e. for the motor and the generator, based on the estimated required power. In an example embodiment, the operating point is selected in such a way that the generator produces the estimated amount of power at a rotating speed of the motor that is fuel efficient and in the preferable operating rpm range of the motor. In an example embodiment, the rotating speed of the motor, and accordingly of the generator, at the operating point is selected.

[0038] In an example embodiment, in which all the power is generated by the motor and the generator, the operating point is selected in such a way that the power generated is above the estimated momentary power requirements of the processing plant with a predetermined safety marginal. In an example embodiment, the running speed of the motor is selected taking into account the fuel consumption and generated power using a power and consumption curve of the motor and generator, an example of which is shown in Fig. 3.

[0039] Fig. 3 shows an example power and consumption curve of a motor and generator in an example embodiment. Fig. 3 shows the power generated 310 and the fuel consumption 320 on the rotating speed range 330 of the motor and generator. The unit of the rotating speed 340 shown is rounds per minute, the unit of fuel consumption 340 shown is g / kWh and the unit of power 350 shown is kW.

[0040] In a further example embodiment, in which in addition to the power generated by the motor and the generator an energy storage is available for discharging or charging, the operating point is selected in such a way that the power generated corresponds to the estimated average power requirement of the processing plant and the desired charging discharging of the energy y storage, i.e. the energy storage is discharged for momentary power peaks. In a further example embodiment, the generated torque is taken into account in addition to the rotating speed in order to operate at an optimal operating point on the power-torque curve of the motor.

[0041] At step 230, the rotating speed of the motor is adjusted in response to the selected operating point and accordingly the rotating speed of the generator is adjusted. In an example embodiment, the adjustment of the motor speed is carried out automatically by the control element. In a further example embodiment, an operator adjusts the motor speed in accordance with the selected operating point.

[0042] In an example embodiment, the steps 210 to 230 are repeated at predetermined intervals in order to estimate the power requirement and to operate the motor at a preferable operating point. In such a way the motor and generator are kept operating in a preferred manner even if the operating circumstances of the mineral material processing plant vary.

[0043] In a further example embodiment, the motor speed is adjusted for reasons other than the selected operating point, for example certain situations the motor needs to be driven at a certain predetermined rotating speed in order to carry out maintenance, for example exhaust gas cleaning system regeneration. Also in such a situation, the mineral material processing can proceed as the mineral material processing devices can be operated independent of the chosen speed of the motor 140 and the generator 150.

[0044] At step 240, power is generated with the generator driven by the motor at the selected operating point. The frequency of the AC voltage generated is dependent on the rotating speed of the motor. The voltage is maintained substantially constant at the desired value independent of the frequency. In an example embodiment, the desired voltage is 400 V.

[0045] At step 250, the AC voltage generated is converted into DC voltage using a rectifier element 160. In an example element the AC voltage is converted into DC voltage of 550 V.

[0046] At step 260, the DC voltage is provided for the at least one inverter element 170a-c and converted into AC voltage to drive the electric motor or motors connected to the inverter element. The DC voltage is converted into AC voltage in accordance with the requirements of the mineral material processing device being driven with each electric motor. In an example embodiment, the at least one inverter 170a-c converts the DC voltage of 550 V into AC voltage of 0 to 400 V with a frequency of 0 to 200 Hz depending on the requirements of the electric motor being driven. Accordingly, the rotating speed of the electric motor or motors used to drive the mineral material processing devices 110,120,130 is independent of the adjustments to the operating point of the motor 140 and generator 150, i.e. rotating speed of the electric motors used to drive the mineral material processing devices is not affected by the adjustment.

[0047] Without in any way limiting the scope of the appended claims, some technical effects of the system according to example embodiment are explained in the following.

[0048] The mineral material processing plant operating method according to example embodiments is configured to provide uninterrupted operation independent of power generation operating point. The mineral material processing plant operating method according to example embodiments is further configured to enable energy efficient mineral material processing.

[0049] Accordingly, a technical effect of example embodiment of the invention is to provide operational security. A further technical effect of the example embodiments of the invention is to enable energy efficient power generation. A still further technical effect of the example embodiments of the invention is to increase environmental friendliness. A still further technical effect of the example embodiments of the invention is to increase the lifetime of power generation elements due to operating at a preferred, or optimal, operating point.

[0050] Various embodiments have been presented. It should be appreciated that in this document, words comprise; include; and contain are each used as open-ended expressions with no intended exclusivity.

[0051] The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

[0052] Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

CLAIMS1 .A method of operating a mobile mineral material processing plant, comprising estimating power needed for operating the mobile mineral material processing plant; selecting an operating point for a motor and a generator driven therewith based on the estimated power; adjusting motor speed in response to the selected operating point; generating AC power with the generator; rectifying the generated AC voltage into DC voltage; and converting the DC voltage into AC voltage with at least one inverter element in order to drive at least one electric motor connected thereto in accordance with the requirements of the mineral material processing device driven with said electric motor.

2. The method of operating a mobile mineral material processing plant of claim 1 , wherein estimating the power needed for operating the mobile mineral material processing plant comprises estimating the maximum power needed.

3. The method of operating a mobile mineral material processing plant of claim 1 or 2, wherein selecting an operating point for the motor and the generator driven therewith based on the estimated power comprises selecting an operating point in which the estimated power needed is generated at a rotating speed of the motor that is fuel efficient and in the preferable operating speed range of the motor.

4. The method of operating a mobile mineral material processing plant of any preceding claim, wherein generating AC power with the generator comprises generating AC power with a predetermined voltage and with a frequency dependent on the rotating speed of the motor at the selected operating point.

5. The method of operating a mobile mineral material processing plant of any preceding claim, wherein estimating the power needed for operating the mobile mineral material processing plant comprises estimating a power desired for charging, or discharging, an energy storage element.

6. The method of operating a mobile mineral material processing plant of any preceding claim, wherein selecting an operating point for a motor and a generator driven therewith comprises selecting an operating point based on rotating speed of the motor required for maintenance.

7. A mobile mineral material processing plant (100), comprising a motor (140); a generator (150) driven with the motor (140); a rectifier element (160); at least one inverter element (170a-c); at least one electric motor connected to the at least one inverter element (170a-c) for driving at least one mineral material processing device (110,120,130); and a control element configured to cause operating the mobile mineral material processing plant (100) according to the method of any preceding claim 1-6.

8. The mobile mineral material processing plant of claim 7, wherein the at least one mineral material processing device (110,120,130) comprises a crusher, a feeder, a conveyor, a crawler track drive, a material air blower, a hydraulic pump or a screen.

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