Proceedmqe of the 7 th International Working Conference on Stored-product Protection - Volume 2

The development of grain storage silo in Tianjin, China

Zhang Chengguang!

Abstract

SIlo IS a kmd of modern grain storehouse, which covers asmall area and has a larger storage capacity per unit area. Itis easy for the realization of mechanized and automatedoperations as well as scientific management. The silo canmeet the requirement of high workmg efficiency, largestorage capacity and fast gram CIrculation The storagecapacity in silos has increased quickly m China. The stategram warehouse m Tianjm urban possesses more than 50 %of the total national silo capacity.

The Types of Grain Storage Silo

The height and the diameter of silos in Tianjm are usually 15- 35m and 6 - Sm, respectively. The diameter of somesteel plate silo IS over 8m. A group or several groups of silosand working towers are together formed a whole structure.Smgle-row or multi-rows arrangement makes the shape ofsilo group a square or a rectangle, which is to be specifiedaccording to the topography, technology, engmeeringgeology and construction conditions.(1) According to their working functions, the silos are

divided into four kinds as follows: the receiving silo,the storage silo, the transfer silo, and the raw matenalprocess SIlo.

o The receiving silo. It IS responsible for receiving thegrams from peasants and farms and not used for long termstorage. There is only some small scale or movablemachinery in it.

o The storage silo. The silo IS used for long- term gramstorage. Its storage capacity IS larger. It IS provided withfixed equipment for grain entering and out-going, cleaningup, weighmg, ventilation, etc. The prevention and curefunctions are perfected.

o The transfer silo: The more advanced mechanized andautomatic large-scale silo is set up in the gram warehousealong the railroad line and port. The stell plate SIlo locatedin XmGang of Tianjm is an example, which capacity of asmgle silo reached 4500t, the total IS 14 silos and the totalcapacity is more than 60,000 tons.

1 Tranjm Gram Bureau, No 34 Liberation North Road, Tianjm300041, P R Chma

o The raw matenal process silo: It IS used for storing thegrain and 011 process raw materials for the different typesof gram process factories. In the past, the bnck silos wereset up, and currently most of the silos were made of steelplate.

(2) According to the construction materials, the silos can bedivided into reinforced concrete, brick and steel platesilos.

o The reinforced concrete silo: The top and body of the siloare both made of reinforced concrete. The slidmg formconstruction technique was used.

o Bnck silo: The body of the silo is made of bricks. Its topwas made of pre-fabncated plate. Because of the low cost,easy construction level, m the initial stage, It was themost popular silo type. Now the production of the claysolid brick had been limited. The development of this typeof silo Will be mfluenced to a certain degree m the future.

o The steel plate srlo: The development of this type IS fast,because the dead weight is light, the requirement for thebase brick IS not very stnct, the standardization degree ishigher, the construction penod IS shorter, and the cost ISlower.

(3) According to the shape of the silo bottom, the silos aredivided mto cone bottom and flat bottom types.

( 4) According to the section of the silo, the shape can bedivided into three kinds: round, square, rectangle, andthe round IS more popular.

(5) According to the capacity and height of the silo, themedium and small-scale deep silos are more popular.

The Accessory Equipment withVarious Functions

The silos are usually set up more advanced accessoryequipment for loadmg and unloadmg, conveying, weighmg,cleamng, prevention and cure. It brmgs the characteristicsof large quantity grain storage and quick CIrculation into fullplay.(1) Entering grain into silo: For the unloading of the ship at

the port, the pneumatic unloader IS often used to conveythe gram into the transfer silo or load the gram directlyonto the truck. For the grain unloading from the tramand truck, the dump pit should be set up beside the siloand along the special railroad section for unloadinggrain. The level of underground water in Tianjm IShigher, for the gram unloading from the train, the

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Proceedmq« of the 7 th Internatwnal Worklng Conference on Stored-product Proiectum. - Volurne 2

small-scale silo IS usually set up beside the railroadspecial purpose lme.

(2) Conveying the gram in depot: The machmes usedcommonly are bucket elevators, belt conveyer, andscrew conveyer They are convenient for gramentenng , out gomg and transfernng

(3) Clearung up gram and dust control: Before the gramenters the silo, the vibrating cleaner and pre-cleanerare used to clean up the grain. The dust control pipesare installed and connected With the dust controlequipment for the gram entenng, outgomg , cleanmgup, and conveymg.

(4) Weighmg and grain out-gomg: The mechanicalautomatic weighing scale IS used for weighing. Aftergram bemg weighed by the automatic weighmg scale, Itcan be transferred to the outside and loaded onto thetruck For the large-scale silo, the telegraphic signalfrom the vaned mechanical work, lightenmg andbreakdown will be transferred to the central controlroom to be regulated and controlled.

(5) Checkmg to the SItuation of stored gram, a senal ofelectroruc equipment for morutonng the temperature,moisture content, atmosphere composition, and theactivity of insect pests IS commonly used.

(6) The equipment for controlling msects and mould mcludeapplying insecticide unit and multi functional pipingsystems The mechanical ventilation, temperaturedropping, precipitation, Circular fumigation tor killmginsect, low dosage funugation for storage, and storageunder controlled atmosphere can be done.

Silo Grain StorageSafety and Preservation

In accordance with the change of 'three temperatures' inthe silo and peculiar law of msect and mould actrvity, thecorrespondmg scientific methods are used to ensure thesafety of the stored gram.(1) Strictly control the quality of the gram entered in silo:

The entered gram should be clean, saturated, and non-msects. The gram, whIch IS dIfferent m vanety andmOisture content, should be stored m the dIfferentsilos. the polluted, detenorated and heat-generatmggrain IS prohibited from entenng the silo

(2) Grasp the sUitable opportunity for entermg the silo: Forthe gram to stored over a long penod, the sUitable timeIS from the end of autumn to the low temperature seasonat the begmmng of spnng. After being fIlled With grain,the silo should be properly sealed Thus the gram storedm silo can be retamed a lower temperature over a longpenod. If the stored gram entered m a SIlo IS not samebatch or ongm, the difference m gram quahty should bepaId attention

(3) The silo transfer or ventilation, temperature dropping:When gram has been stored m a silo for more than half ayear, transfernng or ventilation should be earned out.WIth the lower temperature of gram, the storage timemay be properly extended to avoid the transfernng orventilation in summer. When the gram was entered theSIlo in summer, then the ventilation and temperaturedroppmg should be done at the end of autumn. Theventilation pipe system had been mstalled in Tianjingram storage SIlo for mechanical ventilation Thearrangement of pIpe IS like the shape of the Chmesecharacter "I" and "=f~". Now the multi-purpose pipmgsystem IS bemg used in the whole nation. The benefit ofthis design IS not only m good ventilation effect, butalso in many other prevention and cure functions.

(4) COz atmosphere controlled gram storage: Fill COz mto

the silo, wluch IS sealed properly Regulate theatmosphere compositron in the SIlo to control theactivities of msects and mould, and to delay agmg of thegram and detenoration m quality. The ratio of COz inatmosphere m silo should be above 70% and should notbe reduced lower than 35% withm 14 days. Whenfilhng COz, the mul ti purpose pipmg system IS used topromote the circular ventilation m the silo

(5) Because of the big capacity of the silo, we insist thatafter a silo was emptied out, It should be cleaned upthoroughly, then the new gram can be loaded m

The Comprehensive Managementfor Grain Storage Insects

There IS a lot of stored gram m SIlos. It IS quite easy thatthe stored gram get damp and heat because of the respirationof gram, msects and mould, especially in the high-temperature season. After the gram was entered the silo,ItS temperature Will drop very slowly and IS suitable for themsects actrvity over a long penod so that the gram willheat Many safe, economic and effectrve methods are usedto prevent and cure the msect.(1) The clean up and samtatIon to silo: There should be no

resIdue gram, no dust and no msects m the emptiedsilo The Windows, walls, and floor as well asmachmery eqUipment m the SIlo should be clean up orstenhzed penodlcally,

(2) Gram protectants: The protectant should be mIxed mspnng With the gram to spend m summer. If the wholegram m silo was mIxed WIth protectant or It IS donealternately m different layers of gram, the prevetioneffect will be the best If It IS done only on the surfaceof gram pile, the multI-purpose pIpe system should beused to carry out the Circular ventilation to make theagent spread evenly Once the protectant was apphed,the gram pile or the SIlo should be properly sealed.

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Proceeduute of the 7 th Internatwnal Worhng Conference on Stored-product Protectwn - Volume 2

(3) The storage under low dosage of apphcation: Thestorage under low dosage of application IS often carriedout when the temperature IS lower such as m thesprmg. After applymg low dosage of msecticide, thesilo should be properly sealed, and the circularventilation should be done m a shorter tune

(4) Fumigation: In ordre to make fumigant gas evendistribution mner the silo, the multi-purpose pipmgsystem can be used for the mechamcal ventilation. Thecircular fumigation with methyl bromide or phosphinecan be done by means the pIpe system mentioned above,and the lethal effect may reach up to 100 %. Dunngcircular fumigation, due to the danger of mflammation

and explosion resulted from the mixture of phosphmeand air , It should be taken to mom tor the concentrationof phosphme m atmosphere for ensuring the safefurmgation.

Modern silo IS provided WIth the advanced mechanical andelectncal equipment, and ItS economic benefit is better. Itis expected that the modern silo Will be developed m thefuture m Chma.

References

DaVId, S., 'SIO warehouse' m 'Overseas stell-plate silotechnology material' pubhshed m USA, 79p.

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