CC BY
54
Section 10. Technical sciences
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-194-195
Muratov Khakim Muratovich, Institute of Power Engineering and Automation of the Academy of Sciences, Uzbekistan, Tashkent Isakov Abdusaid Jalilovich, Tashkent Institute of Irrigation and Melioration, Uzbekistan, Tashkent, E-mail: [email protected] Tukhtamishev Botir Kunishevich, Institute of Power Engineering and Automation of the Academy of Sciences, Uzbekistan, Tashkent
Assessment of energy efficiency of the work of pneumatic transport at raw cotton transportation
Abstract: Results of studies on effective functioning of pneumatic transport at raw cotton transportation in operating ginning factories of the Republic of Uzbekistan are considered in the paper.
Keywords: cotton, of transportation, reliability, method of creating, pneumatic-transport, power consumption, efficiency of ventilator.
Raw cotton transportation from warehouses to the production factories is carried out by pneumatic transport. This is facilitated by a number of advantages in comparison with the other forms of transportation: work reliability, simplicity of designs, simplicity of maintenance and repair, compactness and minimal material loss at transportation. In addition, raw cotton transportation by air flow contributes to the loosening of cotton and its moisture removal, as well as to the pre-cleaning from small-size impurities when it passes through the separator.
The principle of operation is based on the ability of air to transport material in suspension at its motion through the operating pipeline.
Air motion is ensured by the pressure difference at the beginning and the end of pneumatic-transport unit. According to the method of creating the pressure difference at the beginning of operating pipeline (excess pressure) or at its end (depression) one could distinguish pneumatic-transport units of suction, pressure and suction-pressure types [1; 2; 3].
Pneumatic-transport units of suction-type are used for raw cotton transportation on the ginning factories. An essential advantage of suction type unit is the fact that it allows without any troubles to change the location scheme of operating pipelines, depending on the location of warehouses and bale sites on the territory of factory pre-machining centers.
An efficiency of pneumatic-transport systems varies depending on the capacity of ginning factory. For the modern one-battery ginning plant it amounts up to 12 tons of raw cotton per hour.
Determining the actual parameters of power consumption of pneumatic-transport units in real conditions of operation is one of the main objectives of effective use of this equipment.
Total consumption of electricity as the main source of energy for ventilation systems may be represented in the following form:
I p = Pns + Pe.c, kW (1)
where: Pn e - is an installed capacity of the fan drives; PB c - a capacity of additional (auxiliary) equipment used in ventilation systems (lighting, automation, etc.).
In general terms, for all electric motors of pneumatic air-blowers (fans, smoke exhausters, pumps, compressors) an installed capacity is given by:
P =-
L • H
• K, kW
(2)
3600-102-n„-n,-n, where: L - is an efficiency of air-blower, m3/h; ne - fan efficiency (according to the ratings); n„ - transmission efficiency (n„ = 1 -under direct setting of electric motor on a shaft; at sleeve joint n„ = =0,98; at V-belt transmission n„ = 0,95); n, - electric motor efficiency (n = 0,97+0,99); K- power reserve factor, which takes into account a starting torque; Hn - total developing pressure, kg/m2,
1
defined by working characteristic of an air-blower; —77—7 - free fall acceleration, H/kg.
102-10-
If Hn - is a total developed pressure, then (2) has the form:
Pn. =---K, kW (3)
3600-1000 nn -n.-n,
The value PB c practically does not depend on ventilator characteristics, being the constant and considerably less than Pn.B.
To reveal the real characteristics ofventilation system it is necessary to determine:
— efficiency of ventilator (air-blower), L in m3/s or in m3/h;
— static and dynamic pressure developed by a ventilator, Hc, Hd kg/m2 or in millimeters of water column;
— ventilator wheel speed, n, rev/min;
— power consumption on ventilator shaft, kW;
— density of air, p, kg/m3
To determine an actual efficiency of ventilator it is necessary to know the cross-section of air pipe and air speed.
Q = S-V, m3/ c (4)
To determine air speed m/s, depending on assumed range, at V= = 0,4 +15 - wing-gauge anemometers are used; at V = 1+35 - cup ones are used as well as micro-manometers with pneumatic pipes.
The measurements should be performed on straight portions of the channels with diameter length l = 5+8, with constant cross-section and smooth walls.
Static pressure is measured by micro-manometer:
Hc = p-q-{h - ho )• sina-10-2, Pa (5)
where: p - is a density of fluid in micro-manometer, kg/m3 (for alcohol it equals to 800+820 kg/m 3); q = 9,81 - free fall acceleration,
The substantiation of energy-saving technology and field tests of universal machines for tilling the soil in interrows of gardens
m/s2; h - scale reading at measuring; h0 - starting scale reading, mm; a - tilt angle of the pipe relative to the horizon, degree. Dynamic pressure is determined by the formula:
W2
H,=-P.
Pa
Hence air speed is:
У =
2H
P
m / с
And average speed along the route is
m / с
YV
(6)
(7)
(8)
where: n - is a number of measurements.
In case of the deviation from standard conditions it is necessary to introduce a correction factor.
In fact, the power consumption P can be determined by a direct measurement:
s ■U ■ I ■ cos^
P = -
1000
(9)
- the definition by the formula (2) of annual energy consumption taking into account the use factor;
- the determination of the demand factor of power K :
l сп
P„
Кп = , (11)
факт
where Ррач - is a design (required) power of electric motor, kW; Рфкт - actual (installed) power of electric motor, kW.
Excess expenditure may be determined using the notion of "specific consumption" - an amount of energy consumed from the circuit referred to each kW/h of effective work: Ксп +a(l-nntt)/ Kr
AW = -
К n
сп I n
(12)
where U - is a mains voltage, B; I - an actual current in ventilator electric motor, A.
Then, rated power use is compared with actual one:
AW = Wnp - Wp, (10)
where Wnp - is an actual power consumption at project capacity of electric motor; Wp - power use at rated power consumption of electric motor.
In case of overstating the power capacity of electric motor, excess expenditure may be determined without the readings along the route. The procedure for calculation is as follows:
- the definition of actually required power of electric motor;
References:
where a = 0,7 4 0,9 - is a factor depending on the design of electric motor; n„p - efficiency of ventilator with account of efficiency of transmission and electric motor:
n„ep = ne 'tfn 'tfs; KT - a rate of working hours use. In case of machine maximum use:
i + «(i-n)/KT 1-n „
' nep
a AW
Relationship p ——-determines the value of power loss.
AW =-
(13)
AW
According to:
AW, = P, 0 (14)
where T - is an operating time ofventilator during the year, h.
Thus, according to above expressions the energy-saving parameters of operated pneumatic transport units at raw cotton transportation to ginning factories are defined.
1. Guide on primary processing of cotton. Book 1. Tashkent, "Mehnat" - 1994 -574 p.
2. Guide on primary processing of cotton. Book 2. Tashkent, "Mehnat", - 1995. - 395 p.
3. Hashimov F. A. Optimization of energy use in textile industry. - Tashkent; Fan. - 2005-250 p.
DOI: http://dx.doi.org/10.20534/ESR-16-9.10-195-198
Musurmonov Azzam Turdievich, Samarkand Agricultural Institute, the Republic of Uzbekistan,
E-mail: [email protected].
The substantiation of energy-saving technology and field tests of universal machines for tilling the soil in interrows of gardens
Abstract: In the article there are analysed the technologies of tilling the soil in interrows of gardens. Studying the existing constructions of machines, the authors proposed a new construction of the machine, which carries out all the operations on tilling the soil in interrows of gardens.
There were carried out experimental works under field conditions, determined the optimum depth of loosening the soil at the unit speed of 1,48...1,60 m/s, there was revealed the parabolic dependence of the change of the traction resistance.
Keywords: garden, row, device, flatcutler, cultibation.
The ploughing of the soil in a main agrotechnical method, which creates favourable conditions for the grouth of fruit trees, forms and loosens the layer of the soil, contribute to the retention thaw waters, accumulation of moisture in the soil, the distraction of weeds. During the ploughing organic and mineral fertilirers are sealed, and a part of pests is destroyed [1; 2; 3].
The soils in the gardens of the Republic are mainly grey-soils, low-powered, chiefly stony and in some places-pebblesto-
ny. As a result of repeated watering under conditions of mountain gardening the precipitations lead to formation of cemented layer in the dedth of 20-60 sm, which the roots of trees can hardly force-Besides, the crust, formed on the surface of the arable layer negatively influences water-air and food regime of the soil [4; 5; 6].
The main task of tilling the soil in interrows of gardens and vineyards is to supply a good fruit-bearning of trees, ovaring and normal
