其他摘要 | Filter is the key equipment in the irrigation system, which can remove all kinds of
impurities to avoid clogging of emitter. It can improve irrigation quality and operation
efficiency. Taking the irrigation system of irrigation district in Xinjiang as study object,
this paper studied on the hydraulic characteristics and sediment removal capacity of five
filtration systems which is composed of two kinds of filters, such as hydrocyclone with
screen filter(80,100,120 mesh) and hydrocyclone with disc filter(75,120 mesh) . The
results obtained are described as follows:
(1) The local head loss of filters is closely related to flow rate. The local head loss
increases with the flow rate increasing. The local head loss of filters is closely related to
sediment content. With the sediment content increasing, the local head loss of filters
increased before the filters aren’t clogged seriously. Under the same composition of
sediment particles, with the sediment content increasing, the amount of the big sediment
particles increases. Therefore screen and disc filters are clogged obviously, and the
allowable running time of system is shortened. Degree of clogging and allowable running
time negatively correlates. In the same condition, the local head loss of screen filters is
smaller than disc filters, but the running time of screen filters is longer than disc filters.
The local head loss and the flow rate of filters change slowly then rapidly with running
time increasing. When the local head loss of screen filters and disc filters reach 2~3m and
4~5m, the effect of the clogging becomes obvious, then the head loss begins to increase
rapidly, and the flow rate begins to reduce rapidly, that affects the normal operation of
system, therefore the screen and disc of filters should be flashed.
(2) The general characteristics of the total separation efficiency in five filtration
syst s manifestation: the greater mesh, the greater total separation efficiency. Under
experiment condition,the general characteristics of the grade efficiency in five filtration systems is that all the grade efficiency is less than ten percent when the size of sand
particle is less than 50μm, and, that all the grade efficiency is one hundred percent when
the size of sand particle is more than 100μm, that the grade efficiency of five filtration
system has much difference when the size of sand particle between 50μm and 100μm,
mainly manifestations: hydrocyclone-120 mesh disc> hydrocyclone-120 mesh screen>
hydrocyclone-100 mesh screen> hydrocyclone-75 mesh disc> hydrocyclone-80 mesh
screen. In terms of sediment separation effect, the sediment removal capacity of disc filters
is better than screen filters.
(3) Under experiment condition,the d50 of sediment filtered by five filtration systems
have little difference, which are about 6~8μm. The d98 of sediment filtered by disc filters
are smaller than that by screen filters, and all the d98 are less than 40μm, that can meet
requirements of water quality in drip irrigation. |
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