BELAZ OJSC, the management company of BELAZ-HOLDING, has received numerous requests for the possibility of acquiring mining equipment that uses gas as a motor fuel. To understand these recent developments in the market, senior engineers of Belaz UGK NTT* have helped us understand this new market trend.
Most often these requests have no immediate order in mind for a gas-powered dump truck, but they are inquiries on the possibility of such a product. Consumer interest is due to a number of reasons. First, it is currently the low cost of a liter of natural gas compared to diesel fuel. Secondly, quarry equipment is most convenient for «gasification»: it is operated not far from its location, and one filling station can serve the entire fleet of dump trucks, unlike the vast majority of vehicles moving on public roads, for which it is necessary to have gas stations along the miles of the highways. Thirdly, the transition to gas significantly improves the environmental situation in usually heavily polluted quarries.
Consider this problem of switching to gas from a safety perspective. Technologically, both propane-butane or methane can be used as a gas engine fuel. The gas can be stored in a vehicle either in compressed (compressed) or liquefied form. For equipment operating in a quarry, however, only methane can be used, due to it being lighter than air.
Another argument in favor of choosing methane is the fact that BELAZ dump trucks with a lifting capacity of 90 tons or more have an electromechanical transmission. In case of leakage, propane-butane, which is heavier than air, can seep into the electrical transmission contacts, which can lead to disastrous consequences. The second important factor in favor of methane is the amount of fuel that can be placed in a dump truck. Other things being equal, LNG (liquefied natural gas — methane CH4) allows for 3 times more fuel storage then CNG (compressed natural gas). Thus, when using LNG, the number of refills during a certain period of time will be three times lower — and yes the duration of one fueling stop is noticeably shorter. For quarry equipment, the operation of which is expensive, both the number of gas stations and the duration of one gas station stop are critical indicators. Therefore, the best gas engine fuel for mining equipment is LNG.
To clarify, for the use of LNG as a fuel tank, a cryogenic tank is used (the Dewar vessel is, in fact, a thermos bottle), since the LNG temperature is –162° C and the LNG preparation system, set up before pumping the fuel into the engine’s combustion chamber (evaporation in order to obtain the required gaseous portion of LNG with parameters set by temperature and pressure), is rather complicated.
There are a number of circumstances that limit the widespread use of LNG on mining equipment. The first is the absence of a sufficient number of gas liquefaction plants in the field of operation of BELAZ. For example, in Russia there are only two such regions: the Kola Peninsula (a plant in Petrozavodsk) and Kuzbass (a plant in Novokuznetsk. The second is the need for serious investments in the creation of infrastructure for LNG in the places of operation required for delivery, storage, refueling of dump trucks, gas equipment service And finally, the third is the high price of gas dump trucks compared to conventional diesel ones (the high cost of a «gas» engine and a cryogenic tank for LNG).
Today there is a perplexing situation on the Russian market, when gas sellers do not see the point in building liquefaction plants in places where the number of consumers is below a certain threshold, while the consumers do not order gas equipment, since there are no filling stations, and so BELAZ, in the absence of orders for gas equipment, does not produce dump trucks with LNG engines.
Gas in a power plant can be used in two different ways. First, as mono-fuel in the so-called gas piston engine (only gas is supplied to the combustion chamber, ignition carried with a spark). When converting a diesel engine into a gas piston engine, a deep and therefore expensive modification is required: the original pistons, the original camshaft, the original fuel system, the need to install ignition and automatic control systems, the original intake and exhaust valves, and that’s not all.
Secondly — in the gas-diesel mode: both gas and diesel fuel are supplied to the combustion chamber; ignition of the diesel fuel happens as usual, from the compression, and the gas ignites from diesel fuel. It is possible to install a relatively inexpensive attachments on a diesel engine for its conversion to gas-diesel mode of operation. The drawback of this scheme is the need to install two fuel systems (diesel and gas) on a dump truck, and also depending on the availability of two infrastructures for the delivery, storage and refueling of dump trucks with both types of fuel. And its great advantage is that, in the absence of gas, such an engine can work like a normal diesel. Depending on the mode of operation of the power unit, the system constantly adjusts the ratio of portions of diesel fuel and gas supplied to the combustion chamber.
Integrally, the ratio of combustion in the working cycle mode by weight of gas and diesel fuel is usually 45% and 55%, respectively. But it can be different: for example, the E-control company (USA) declares that when using its equipment this ratio is 93% gas and 7% diesel fuel – however, their product is, unfortunately, not tested on quarry equipment as well as very expensive. It should be borne in mind that numerous companies offering diesel engine switching to gas-diesel mode of operation, firstly, as a rule, do not own tested methods of preparing (evaporating) LNG before being fed into the engine’s combustion chamber, and secondly, they usually declare 70—80% diesel substitution by gas. On certain operating modes of the engine, this is quite achievable; in practice, exceeding the level of 50% is quite a decent result. The fact that, as a rule, at idle (waiting for loading) and at maximum power mode, the engine runs in a purely diesel mode, greatly influences the integral percentage of substitution.
Suppliers of diesel engines for BELAZ dump trucks do not yet have any gas-piston or gas-diesel versions of their engines, adapted for use in mining equipment. Nevertheless, meeting the numerous demands of consumers, as well as on the basis of market analysis, OJSC «BELAZ» independently implements several projects for the creation of mining dump trucks on gas-engine fuel.
One of them is the transfer of Cummins KTA50-C engines to the gas-diesel mode of operation on two BELAZ-75139 mining dump trucks with a payload capacity of 136 tons at the cite of the Kovdor mining and processing plant. Suppliers of attachments are the German company Heinzmann, the fuel system is the Moscow-based enterprise Geliymash. The fuel system is being finalized and equipment is being adjusted.
It is also necessary to mention the work of the Siberian-Energo Novokuznetsk enterprise, which he carried out on the transfer of 20 BELAZ dump trucks with a carrying capacity of 136 tons to a gas-diesel mode of operation with minimal participation of OAO BELAZ. This project is also being finalized.
The next significant project of OJSC BELAZ is the manufacture of the dump truck BELAZ-75476 with a lifting capacity of 45 tons with the KUNGUR-550 gas piston engine, developed on the basis of the YaMZ-240NM2 power unit. Conversion and supply of the engine, as well as the development and supply of the fuel system, was made by Tekhnologiya 1604 LLC from Ekaterinburg. Engine power increased to 550l.s. (against the currently available 500hp from YaMZ-240NM2). Fuel efficiency in terms of grams per kW / h is almost equal to fuel efficiency in grams of diesel fuel per kW/h of the YaMZ-240NM2. Thus, in the first approximation at the cost of diesel fuel and the cost of LNG (by weight), it is possible to estimate the decrease in the fuel component in the cost of transportation. Due to the increase in engine power by 50 horsepower, the machine has become more productive.
Since April 2018, the mining dump truck BELAZ-75746 has been successfully operating in Nevyansky Cementnik JSC, village Cement of Nevyansk district of the Sverdlovsk region. According to the results of the BELAZ tests on LNG, it can be concluded that the use of a dump truck on liquefied gaseous fuel has the following advantages: a reduction in fuel costs in terms of value by a factor of two compared to the new BelAZ-7547 dump truck on diesel fuel; Increased service interval up to 500 motohours versus 250 motohours at BelAZ-7547.
In the future plans of cooperation «BELAZ» with the company «Technology 1604» is the creation of a dump truck of the 7513 family with a carrying capacity of 136 tons with a gas piston engine based on the Cummins KTA50-C diesel engine in 2019 and a dump truck of the 7558 family with a loading capacity of 90 tons with a gas piston engine on the diesel engine. Cummins KTA38-C engine in 2020.
At present, OJSC BELAZ has manufactured the second sample of the dump truck BELAZ-75476 with the following major improvements: the increased capacity fuel tanks ensure the operation of the dump truck for 12 hours; an automatic gearbox is installed; implemented output to the electronic instrument panel in the cabin information from the electronic engine control system.
Nikita Dasievich Volotsky,
1st Category Engineer
Vasily Vasilyevich Duk,
Head of the Bureau of the UGK NTTs
Alexey Nikolaevich Sergel,
head of the UGK NTTs bureau