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the operation management of the central branch of the central branch
the application of the first chapter of the central branch of sprinkler irrigation machine
center
pivot sprinkler irrigation machine (center pivot irrigation system),
also known as clockwise type sprinkler, will be equipped with a nozzle
pipe support in the automatic walking bracket, around the water supply
system of the center point boundary side rotation irrigation of
large-scale irrigation machine.
the advantages and disadvantages of the first sprinkler irrigation machine and the use condition
compared with other sprinkler irrigation equipment, the central axial
sprinkler irrigation system has the following advantages and
disadvantages.
one, advantages
1, the central branch
of sprinkler irrigation is by far the highest degree of automatic
sprinkler irrigation equipment, can save a lot of labor.
2,
center shaft type sprinkler unit inlet is located in center of the lower
portion of the support, as the center of the support is fixed, so water
supply system is very simple.
3, the guidance and
synchronization control system is only related to the fixed center
support, reliable operation, simple management.
4, after the
completion of a water cycle (rotation), the unit stays in the starting
position, to prepare for the next irrigation.
5, can timely and accurately control the amount of irrigation, convenient management, irrigation water utilization.
6, the central branch of sprinkler irrigation function to improve the efficiency of chemical fertilizer and pesticide use.
7, the irrigation operation flexibility, is conducive to the preparation of practical use of electric power plan.
for all irrigation equipment, in order to reduce the investment in the
area of irrigation, it should try to use the smallest equipment and
irrigation area as much as possible. the center shaft type sprinkler,
due to the cost of the equipment and the unit length is proportional,
and the irrigation area and the unit length of the square is
proportional to the, so irrigation area should be is a circular as large
as possible.
two, shortcomings
1, if you do not use
angle device, center pivot irrigation machine the irrigated plots of
circular contour outside left about 20% of the irrigation area, if the
angle device, significantly increase the cost and complexity of the
equipment.
2, the intensity of irrigation irrigation area of
the outer circumference of the circle is very high. if the corresponding
measures are not taken, the surface runoff is usually generated. when
the profile is used in the rocker arm, the value is usually greater than
100mm/h; the modified value is usually greater than 150mm/h when the
scattering nozzle with a small range is used.
3, the surface
runoff problem caused by high sprinkler irrigation intensity was reduced
or eliminated, and the irrigation mode of "ground water irrigation"
should be used. in extreme cases, in order to avoid the emergence of
surface runoff, even the center shaft type sprinkler rotates a circle
set the time required for less than a day. as a result, increased
political loss and unit maintenance costs, and may reduce the crop
yield.
4, because the length of the unit did not increase at
one end, it will increase the irrigation area with a same width of the
concentric circle, it must be a large number of irrigation water to the
end of the unit. therefore, with other irrigation equipment (system),
the water pipe truss along the high water head loss.
5, in the
slope, the output pipe truss pressure drop in the change of height with
the location and change. if you do not use a pressure regulator or flow
regulator, the flow of the nozzle will be a big change, so that the
uniformity of the unit spray significantly reduced.
6, from an
economic point of view, the central branch of the irrigation machine is
usually irrigation larger. if irrigation is small, the central branch of
the irrigation machine may not be economical.
three, applicable conditions
the central branch irrigation machine is suitable for the irrigation of
the soil of various textures, as well as a variety of field crops,
vegetables, economic crops and grass, etc.. china's northwest, northeast
and north china around and guangdong, guangxi, yunnan guizhou plateau
vast pastoral areas, where contiguous land, crop are unified, the ground
pole wu, drainage ditch obstacles can be used.
the second chapter is about the basic knowledge of the central branch irrigation machine.
the working principle and composition of the sprinkler irrigation machine
in the heart a shaft type sprinkler consists of center support, tower,
spraying truss, the end of the cantilever and the electrically
controlled synchronization system. several cross truss with shower
heads, supported on several tower car. the truss is connected with the
flexible joint, so as to adapt to the sloping field. each tower is
equipped with about 1km of the motor as the running power, auxiliary
power available grid and diesel generator set, also equipped with
special safe and reliable synchronous system controlled by electric for
hoist motor car of the tower. has the function of automatic warning
function of rainfall protection and fault. the latest of the tower
started, according to the working condition, one by one starting
adjacent tower. all of the tower is a with a running up, around the
center axis of rotation, in order to achieve a circular area of
automatic spraying operations.
the composition of the central
branch of the sprinkler irrigation machine is shown in figure 2.1. as
can be seen from the figure, center of a typical configuration of
support shaft type sprinkler irrigation machine consists of a center
support, truss, tower, the tail ends of the cantilevers, control systems
and emitters etc. six major components. in addition, sometimes the
center pivot irrigation system is also equipped with end gun or anchor
device.
center support
bearing in mind is the center of rotation of the sprinkler, is also the
outlet, its external is a composed of columns, beams and floor of the
pagoda shaped frame, middle part is rotating sleeve and a support shaft
in bending. the upper part of the rotary sleeve is fixed on the frame,
and the lower part is connected with the water source. branch elbow axis
vertical part is positioned on the rotating sleeve, in which free to
rotate; the other end is connected with the hand span truss water pipes
are connected by a spherical hinge, to fit the hand span truss due to
topographical variation in the generated along the vertical direction of
the displacement. the floor with anchor bolts fixed on a concrete
foundation to maintain stability. the main control box is installed on
the frame of the central support. a fixed point stop device is arranged
on the rotating sleeve. the electric ring, the lamp and the pressure
gauge are arranged on the horizontal pipe of the supporting shaft.
two, truss
the truss frame is mainly composed of water pipe, triangular frame
string and reinforcement etc.. the truss is divided into three types,
which are divided into the first span, the middle span and the end span.
in order to to adapt to changes in terrain group level in the length
direction to ensure sprinkler walking synchronization, and the spherical
hinge connection is adopted between the span truss, the water pipe by
flexible joints or rubber sleeve connection. truss span (length) is
usually 30~60m, the most common truss span length of 40~50m. water pipe
nominal diameter is 100~250mm, the water pipe nominal diameter is the
most commonly used 168 (165) mm.
because of the flexible
connection between the cross truss, the central branch of the irrigation
machine in the unit length direction of the direction of the slope of
30% (16.7) of the block. in relatively shallow furrow in the field
conditions, the most typical configuration memory unit in the walking
direction of course adapt to the slope up to 20% (11.3 degrees) plots.
nevertheless, practical experience proves that the file ridge and furrow
depth is greater than 0.15, the unit may in the slope is greater than
15% (8.5 degrees) of the slope in walking. for water transport branch of
large diameter, long span truss unit, the maximum slope may be slightly
smaller to. in particular, the idea that the central branch of the
sprinkler irrigation machine is suitable for flat ground is wrong. it
can be said that, only to be able to use large and medium-sized
agricultural machinery to cultivate the land, you can use the central
branch irrigation machine for irrigation.
the vertical distance
between the lower part of the truss and the ground is referred to as
the ground clearance height, and the average is 2~4m, and there are as
high as 5m. the ground clearance height is determined according to the
height of the crop height and the length of the unit. needs to be
pointed out is that if the crop irrigation for potato, wheat and grass,
dwarf crops and plots in the direction of the unit length of smooth,
should choose smaller ground clearance height, to improve the unit's
stability.
three, tower
the tower frame car by the column, beam and beam composed of a frame
and power transmission device, and rubber wheels. the upper part of the a
- shaped frame and a truss necklace; the lower part of the beam is
fitted with a wheel reducer, and the rubber wheel is connected. the
power machine is installed on the beam, to transmit power to the wheels
through a transmission device, the pudong tower walking forward. the
transmission device comprises a two stage reducer and a universal joint.
the power machine can make the motor, gasoline engine or water motor,
is the most commonly used motor. when the power machine for motor, the
reducer are made into a whole, so also known as motor reducer; and
wheels connected to the speed reducer said wheel gear deceleration
device or secondary speed reducer. reducer gear reducer, can also be a
worm reducer; but secondary reducer must is worm reducer, because it
requires a self-locking function, or when the wheels are located on the
slopes will downhill scrolling.
1, drive motor power
the car of the tower drive the magnitude of the power of a motor and a
reducer types, truss water pipe diameter, truss span and irrigation
plots of drawings, ridge height and the slope of size. for a reducer
worm gear reducer unit, due to the low transmission efficiency, power
motor usually is 1.1~1.5kw; for a speed reducer gear reducer unit, due
to the high transmission efficiency, motor power usually 0.55~0.75kw.
2, the sprinkler is not the shortest time required to rotate a circle
the shortest time required for each rotation of the central branch of
the sprinkler irrigation machine is calculated according to the
following formula:
t = 2 pi l/ (60 - nd/i)
2-1 type simple:
t = l/ (30nd/i)
the shortest time required for each rotation of the central branch of the t--- center of the h;
l-- support center to the end of the tower car distance, m;
the n-- engine speed, r/min;
d-- wheel outer diameter, m;
i-- two stage reducer of the total ratio, dimensionless.
such as, a configuration of eight cross 50m truss center pivot
sprinkler, the distance between the center support to the end of the
tower for 50 * 8 = 400m; matching engine for motor, rated speed is 1450r
/ min; the wheel diameter is 1.28m; two stage reducer overall ratios
2500.
the data into 2--2, t = 18h, the shortest time of the unit per turn for 18 hours.
most manufacturing plant for the production of a typical configuration
center supporting shaft type sprinkler rotates one circle for the
shortest time is slightly less than 24h. if needed, by selecting larger
or smaller ratio of the reducer to change center shaft type sprinkler
not spin in a circle the most short time, through installation and
adjustment in the main control box is the percentage of timer, you can
reduce the walking speed of the terminal tower, increasing the time
required for each turn. this will be in the back.
four, cantilever
the water pipe, the cantilever supporting frame and a wire rope.
adopting cantilever water pipe flange and the end cross truss water pipe
end is connected, the nominal diameter is usually smaller than the
truss water pipe, length less than 20m. the triangle bracket and the
wire rope is the role of support, stable cantilever water pipe.
cantilever has two functions, one is to increase the length of the unit
with a smaller equipment cost, expand the irrigation control area; the
two is to meet the needs of the length of the unit by adjusting its
length.
five, control system
control system consists of a main control box, set ring, tower box,
sentinel shutdown device and cable. these components cooperate with each
other, the central shaft type sprinkler synchronization is reverse
running, walking speed adjustment, operation monitoring, safety
protection, fault alarm and other functions.
1, the main control box
the main control box is installed on the central support. it is the
central control of the sprinkler irrigation machine. all the control
functions of the sprinkler system must be received by the main control
box, the signal is processed and the instruction is sent out.
the main function of the main control box is as follows:
(1) through the collector ring to the tower box power supply, from the
tower to the box according to the tower location decision whether to
supply power to the motor to ensure the synchronization between the
truss, irrigation machine forward or reverse operation.
(2) by
installing percentage timer on the main control panel, to adjust the end
of tower within 1 minute walk, stop time proportional to regulating
sprinkling machine walking speed, control the amount of irrigation
(irrigation depth), to meet the crop water requirements. for example,
percentage timer adjustment for 70%, in a minute before the 70%, namely
42s time, the terminal tower continuous walking; in the next 30%, i.e.
18s time, the terminal tower stop.
(3) by means of a voltage
meter, current meter, thermometer, etc., to monitor the operation of the
unit in the main control box. when the voltage, current or ambient
temperature exceeds the set value, the alarm signal is emitted when the
sprinkler is running.
(4) a signal received from a fixed stop
device, which enables the sprinkler to remain in a predetermined
position, and to stop the supply of the water pump.
(5) when
the terminal tower wheel slippage or can not be blocked moves to get to
set time limit, any two span truss between the angle is too large (for
example, more than 1 degree) or water supply pump stops running, and
display fault tower location.
2 set ring
the collector ring is installed in the center seat, which is provided
with a copper ring and a carbon brush mutually insulated copper ring
contact with east china. the copper ring is fixed, brush with sprinkler
rotation. set electric ring, when each span truss around the center of
the support for the rotary motion, prevent the installation of the tower
in the center of the support and a main control box and box connection
cable winding in the center of the support, ensure the smooth of the
electrical lines.
3, tower box
tower box is installed at the upper part of the tower, the back is
installed synchronous control angle adjusting device, operation of the
micro switch, safety microswitch, ac contactor, thermal relay and a
tower fault signal generator.
the same step control angle
adjusting device is composed of the adjusting rod and cam mechanism.
control angle of synchronous control is not more than 1 degrees. when a
tower on both sides of the truss is connected at an angle to the angle
and operation of micro switch normally open contact is closed, through
the power of ac contactor when the motor is turned on, the tower began
to walk. when the tower on both sides of the truss in a straight line,
running micro switch normally open contact disconnected, the motor power
supply is cut off, tower stopped walking. each tower according to the
adjustment and operation, ensures the synchronization of the sprinkler.
the role of thermal relay is that when a tower of the motor overload,
cut off power to prevent the motor from being damaged due to
overloading. in recent years, due to the motor reducer itself has
overload automatic protection function, the tower box usually is no
longer installed thermal relay.
the normally open contact tower
car fault signal generator and safety micro switch connected. when the
time of the accident, the safety micro switch normally open contact is
closed, the signal generator to the main control box to send a fault
where the tower signal.
times and the end cross tower box in
addition to the installation of the electrical components, is also
provided with a time relay, when the terminal tower wheel slippage or
can not be blocked before reaching the set limit, time relay normally
closed contact is disconnected, the ac contactor to sprinkler and water
pumps stop running.
six, fountain
in the irrigation industry, the emitter is general sprinkler, drip,
micro sprinkler, water gushing water first device. suitable for the
central support of sprinkler irrigation machine is the main type of the
radial head and scattered type nozzle.
1, rocker type nozzle
the specification model of the rocker type nozzle is a lot of, which is
used for the main supporting of the central support. impact sprinkler
are installed in the upper part of the water pipe truss, the jet flow
fired and the horizontal plane into certain angle (nozzle elevation) in
the air.
compared with the scatter type nozzle, the biggest
advantage of the radial head is far. this is especially important for
the soil with low permeability and low speed, because the larger the
range of the water, the smaller the size of the unit area, that is, the
intensity of spray irrigation machine. there are two disadvantages of
the radial head, one is working pressure, the high cost of water supply
pump, the two is the height of the injection, and the loss of
evaporation drift is large. in order to reduce the height of the
injection, the low elevation angle arm type nozzle was developed.
most of the nozzle of the radial head is straight cone. when the
pressure of the unit changes, the flow rate of the nozzle is basically
unchanged. when the elevation of irrigation plots, or water supply water
source is more than one user, the water pressure may fluctuate, should
be considered when using this nozzle (nozzle).
2, scattering type nozzle
at present, there are many different kinds of scattering nozzles
applied to the central support system. scatter type nozzles are usually
used to install the suspension hose under the truss, and some even reach
the canopy of the crop.
the advantages and disadvantages of
the scattering nozzle is the opposite of the radial head. the existing
problem is that sprinkler irrigation intensity is big, easy to produce
runoff; but the range is small, the nozzle is arranged in a small
amount, the number of nozzles is much more.
at present, the
center pivot irrigation system at home and abroad, most of the jet
nozzle america rumors. need to remind a bit, the scattering nozzle
nozzle size is usually adopted 2 kinds of expressions, which is usually
to 1 / 64 or 1 in 128 inches and said nozzle size 10/64 inches (4.00mm)
may also 10/128 inches (200) mm.
seven, end spray gun
at the end of the tail end of the spray gun is installed in suspension.
the so-called end of the spray gun, in fact, is a medium range rotary
nozzle. the center shaft type sprinkler truss and the bracket section
most of the scattering nozzle, terminal unit of pressure is very low, so
we need a booster pump are installed in the upstream end of the spray
gun in order to meet the cosco range of rotating sprinkler working
pressure of demand.
there are three functions of the
installation of the end of an installation. one is to increase the size
of the unit irrigation radius, expand the irrigation control area, the
end of the spray gun in the operation of the unit has been running, the
unit's irrigation area is a radius of the circle. at the end of the gun
only in square plots of four corners near running, to compensate for had
not poured into the region, when the field near the unit at the end of
the poles, trees and other obstacles, avoid obstacles.
eight, anchor device
angle angle angle device arm, arm device or anchor arm system. the
so-called angle device, it can be considered that is in center pivot
sprinkler basic truss end adds a group of flexible truss. at the same
time, the cantilever is also transferred to the end of the flexible
truss.
the device was first developed and applied in the united
states in 1973. the anchor device, center pivot sprinkler irrigation
chance of any shape of the plots, especially a square block. the length
of the angle device is long and short, under normal circumstances, the
typical configuration (approximately 400m field, control irrigation area
of 750 acres) center shaft type sprinkler irrigation machine angle of
the device can be adding acres of irrigated area 100~135.
the
emergence of the ground angle device, customer service the central
branch of the irrigation machine can only irrigation round area of
defects, is a happy thing. but we must also realize that angle device of
walking and spray control system is complicated, the cost is relatively
high, there are not suitable for popularization and application in our
country is. according to a us colleague, of approximately 400m long
typical configurations of center pivot sprinkler irrigation machine,
angle unit price is about 2 / 3 of the typical device; the united states
currently has three states with angle device center pivot sprinkler
irrigation machine more, but its use accounted for only 10% the left and
right.
sprinkler layout of the second section
the main factor that should be considered when designing a central
support sprinkler irrigation project is to select the combination of the
nozzle. the distance between the nozzle and the type or size are the
two main variables.
the goal of irrigation is to provide the
most uniform distribution of water. the coverage area of the distal end
of the central branch of the sprinkler irrigation machine is larger than
that of the near end truss. therefore, the density and the size of the
nozzle should be along the water from the center of the distal axial
branch gradually increased.
most of the center pivot sprinkler
irrigation machine nozzle is fixed size hole (installed at a specific
location in the water pipe), and according to the size where the nozzle
pressure spraying in addition to a certain amount of water. in the
center of the axial injection machine, due to the relatively small area
near the center support, only a very small amount of water, so the
nozzle size is also very small. in many cases, due to the size of the
required irrigation intensity, it is impossible to create a nozzle that
can not only meet the appropriate amount of water, but also can not be
blocked. therefore, the first cross truss may sometimes be too large due
to nozzle size and excessive irrigation. part of this can be
compensated by increasing the distance between the nozzles. but the
nozzle must be close enough to obtain a good cross overlap.
in
the remote truss of central support, the amount of water required is
increased, and the nozzles need to be enlarged, so as to meet the need
of increasing water demand. in some cases, the maximum size of the
nozzle is not in conformity with the requirements of the maximum size of
the nozzle, especially when the unit is very long, or the flow is
particularly large. in this case, may have a three plus at the outlet,
the installation of two nozzle. other possible solutions are to reduce
the nozzle spacing, reduce the flow rate or increase the pressure.
the most common three kinds of nozzle spacing in the central branch of the sprinkler system are as follows:
(1) uniform nozzle spacing. unit water pipe nozzle between the 3~12m
either the same spacing, nozzle flow with them and center pivot distance
between the increase in direct proportion, spray wetted diameter also
increased, but not with flow is proportional to. the wetted diameter is 2
times the range of the spray nozzle.
(2) the nozzle spacing is
the same. water pipe unit is divided into three or four sections, each
section using different nozzles spacing, near the center support at the
greatest distance.
(3) the flow rate of the head is basically
the same, and the change is very small. this requires the nozzle spacing
near the center pivot at about 12m, and at the end of the branch pipe
water decreases to about 1.5m. water pipe nozzle spacing and the nozzle
to the center supporting shaft radial distance is inversely proportional
to, so the spacing and radial distance of product is a constant.
the form of uniform nozzle spacing is the most common. in this way, the
manufacture is simple, and the field installation is convenient.
however, when the uniform nozzle spacing is used, the high working
pressure and high working pressure of large size nozzle is required if
the distance is high. also when irrigation did not cover crop fragile
soil, water droplets produced by the large size of the nozzle may cause
surface hardening, thereby reducing soil infiltration capacity, increase
of surface runoff.
in order to avoid the above problems caused
by large size nozzles, the nozzle spacing is often used in the same
way. commonly used method is near the center support one-third water
branch with 12m spacing of sprinklers, one-third of the intermediate by
6m and distal one-third by 3m. take this arrangement, the water pipe can
be using the same 3m hole spacing and not applicable holes available
blocking plug on. for example, near a center pivot of one-third to water
directly, each of the four water outlet installed a shower; middle
third and an outlet septum installed a shower; distal one-third of, each
water outlet hole are provided with a spray head.
the performance parameters of typical refractive index nozzle for sprinkler irrigation are shown in appendix 2.
is
very similar to the shape and pointer type sprinkling machine and by
more than a dozen tower supports a root elongation spraying pipe,
walking and spraying. the translational sprinkler is a cross body
horizontal translation.
three, the main components of the dyp series of sprinkler irrigation machine
four, cross body selection parameters
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