Maritime University of Szczecin
Akademia Morska w Szczecinie
2010, 23(95) pp. 31–35 2010, 23(95) s. 31–35
Environment protection in transport processes
of soybean seed cake
Ochrona środowiska w procesach transportowych
śruty sojowej
Beata Drzewieniecka
Maritime University of Szczecin, Faculty of Economics and Transport Engineering
Institute of Transport Engineering, Department of Commodities Science and Quality Management Akademia Morska w Szczecinie, Wydział Inżynieryjno-Ekonomiczny Transportu
Instytut Inżynierii Transportu, Zakład Towaroznawstwa i Zarządzania Jakością 70-507 Szczecin, ul. H. Pobożnego 11, e-mail: drzewbea@interia.pl
Key words: soybean, industrial and transport elevators, ecology Abstract
The problem of environment protection against selected properties of soybean seed cake in transport processes and the terminology of the dangerous cargo mentioned in various codes and regulations has been presented. Loose soybean seed cake, apart from larger particles, also includes fine and powdery fractions creating danger of explosion. An analysis has been made of selected industrial and transport elevators aimed at determining the degree of protection of the atmosphere inside those storehouses.
Słowa kluczowe: śruta sojowa, elewatory przemysłowe i transportowe, ekologia Abstrakt
Przedstawiono problem ochrony środowiska przed wybranymi właściwościami śruty sojowej w procesach transportowych oraz terminologię wymienionego ładunku niebezpiecznego w różnych kodeksach i przepi-sach. W skład śruty sojowej sypkiej oprócz większych cząstek wchodzą także frakcje drobne i pyliste, stwa-rzające niebezpieczeństwo wybuchu. Przeprowadzona została analiza wybranych elewatorów przemysłowych i transportowych celem określenia stopnia ochrony atmosfery wewnątrz tych magazynów.
Introduction
Transformations in fodder economy, health safety and world-wide growing demand for soy-bean seed cake used for the production of fodder mixtures create the need for research on this raw material during transport processes.
Transport processes are to be understood as cy-clically repeated operations of storage, transship-ment and carriage by various means of transport, in the course of which the properties of soybean seed cake expose human life and the environment to enormous danger.
During these processes many properties are transformed that are decisive for transport
suscepti-bility and constitute the basic quality factors in the scope of technological and transport quality.
The technological and transport quality factors of soybean seed cake are properties vital in transport, selected out of the properties of this fodder resource. On the basis of the subject’s litera-ture, observation and research, among other things the following can be counted among them: grain composition, shape of particles, density, bulk den-sity, poroden-sity, static and kinetic angle of repose.
In transport seed cakes are classed as dangerous cargo. Irrespective of the means of oil excavation, in codes containing requirements concerning ma-rine transport of dangerous cargo in packages and in bulk, Code IMDG [1] and Code BC [2], in the
original language by-products are termed “seed cake”, and in Polish version of 1974 and 1988 codes were called “makuchy”1.
The name ”expeller” is applied in international turnover of this fodder with reference to homoge-neous residues, that is obtained from one kind of seeds, and “oil cake” to heterogeneous (mixed) residues [3].
In regulations pertaining to transport of dange-rous goods by means of inland vessels (ADN) [4] – European Agreement Concerning the International Carriage of Dangerous Goods by Inland Water-ways, by rail (RID) [5] – Regulations Concerning the International Carriage of Dangerous Goods by Rail and by road (ADR) [6] – European Agreement Concerning the International Carriage of Dangerous Goods by Road, the dry residue which is the by-product of the production of vegetable oil termed in the original language also as “seed cake”. In the Regulation of Minister for Agriculture and Rural Development [7] for domestic interpretations of ADR [8, 9], the term “wytłoki” is used.
Properties of soybean seed cake in transport processes
Soybean seed cake is transported loose or in packages. As loose bulk cargo it is carried by va-rious specialistic means of land and water cargo.
The requirements concerning the transport of fodder are given by standards, codes, international agreements, instructions and published in 2005 GMP international standards2.
The carriage of soybean seed cake by various means of transport as dangerous cargo are con-trolled by respective international regulations: ADR [4], RID [5], ADN [6], IMDG Code [1] and BC Code [2].
Soybean seed cake is included in Class 4.2 as pyrophoric material. In IMDG Code concerning the carriage of dangerous goods in packages and in BC Code giving transport requirements pertaining to
1 IMDG and BC Codes appear currently in English but
are not translated into Polish, as are also ADN, RID and ADR.
2 – GMP 07 (GMP standard for Road Transport in the Animal Feed Sector),
– GMP 08A (GMP standard for the Transport of Feed Materials, Premixes and Compound Feeds by Inland Waterway),
– GMP 08B (GMP standard on the Transport of Feed Materials, Premixes and Compound Feed by Sea), – GMP 08C (GMP standard for the Transport of Feed Materials, Premixes and Compound Feed by Rail Transport).
bulk transport, soybean seed cake is classed under UN Number 1386 and UN Number UN 2217.
During transport various biochemical processes take place in seed cake resulting in the emission of heat energy. Fat content in soybean seed cake may lead to self-heating or even self-ignition.
During marine transport of soybean seed cake the following factors are conducive to self-heating and self-ignition: high air humidity in the holds and its insufficient regulation, exposing the cargo to moistness and wetting, limited possibilities of seed cake temperature control and carrying off the col-lected heat, high seed cake fineness and relatively long transport time.
Moreover, the presence of solvent vapours in soybean seed cake as residue after extraction, and also the presence of large number of dusty fractions may lead to explosion.
Among unfavourable phenomena impairing transport processes there is decreased looseness causing among other things caking and forming of conglutinated layers, resulting in the cargo’s sus-pension in the silos’ outlets termed “bridging” and decreased permeability of transmission pipelines and eventually impeding cargo-handling operations. The caking and conglutination of soybean seed cake cargo is affected by the shape and size of seed cake particles, grain composition, water content, and the time of carriage and storage.
These properties also influence thickening; the flatter the seed cake particles and the higher the content of fine fractions and water content, the lar-ger the tendency of seed cake to cake and thicken progressing in time. These unfavourable processes can be measured by the seed cake’s bulk density and diminished porosity. Soybean seed cake’s high porosity facilitates maintenance operations like ventilation, drying and combating vermin [10].
Thickening and settling of the cargo mass during transport causes a decrease in its volume. In the case of carrying soybean seed cake by ships, the free space over the cargo and the free cargo area thus created favour the pouring of seed cake onto the boards, which increases the threat of the ship losing her stability.
Other negative results of cargo thickening are easier shifting and the development of microorga-nisms leading to self-heating. Self-heating is also favoured by the phenomenon of self-sorting. Where there is movement of particle mass of soybean seed cake, e.g. at gravitational filling and emptying of elevator chambers, during loose carriage in large cargo units and means of transport, the larger seed cake particles gather in central parts of the cargo mass, and smaller particles in the external parts.
In places where fine particles have accumulated, due to decreased free spaces, the development of microorganisms is particularly easy.
In the transport cycle soybean seed cake is unloaded in indirect relation from water means of transport to elevators and then loaded to land means of transport, by which it is carried to storehouses of fodder mixing plants (Fig. 1).
Fig. 1. Transshipment of soybean seed cake in indirect relation Rys. 1. Przeładunek śruty sojowej w relacji pośredniej
In the process of storing soybean seed cake appears in loose form, first of all in bulk or in pac-kages.
The transshipment of loose soybean seed cake can take place in the gravitational, mechanical and pneumatic way. In the course of transshipping seed cake loose there follows an intense shifting of par-ticles and emergence of dust. Apart from larger particles (diameter >1 mm) loose soybean seed cake is also composed of fine and dusty fractions constituting about 4% of the whole cargo, which create explosion danger.
A technological transport quality factor is grain composition, also called fineness degree, determin-ing the size of particles. The markdetermin-ing of fineness degree is aimed at establishing what fractions the seed cake is composed of and the degree of its dustiness. The classification of fineness degree includes: fine meal (0.2 – 1.0 mm), medium meal (1.0 – 1.8 mm) and coarse meal (1.8 – 2.6 mm).
According to PN-74/Z-04097.07 standard per-taining to grain dust composition, among dust of colloidal fineness particles are counted of size from 0.001 to 1 µm, and particles sized 1 to 1000 µm are
considered as dust of microscopic fineness, therein: particles sized 1 to 5 µm are considered as very fine dust, from 5 to 60 µm as fine dust, from 60 to 500 µm as medium dust, from 500 to 1000 µm as coarse dust.
It was found [11] that an explosion may occur in the presence of an external fire source min the fol-lowing conditions:
the dust concentration in a closed space exceeds 20 g/m3 of air and water content in the seed cake
is lower than 8%,
the temperature of layers of accumulated dust exceeds 60°C, in cases of the dust settling on heating pipes.
The limits of the dusts’ explosiveness depend on humidity. The capacity of dusts to explode dimi-nishes with increase of humidity. The explosiveness limit of dust of soybean seed cake equals 20 – 100 g/m3, seed cake of 9% humidity – 300 – 1000 g/m3.
Dusts of humidity above 16% do not explode. In the extraction process of soybean seed cake hexane (UN Number 1208)3 is applied as a solvent of ignition temperature –22°C and limits of explo-siveness in mixture with air from 1.1 to 7.5% volume [1].
Low ignition temperature and low lower explo-siveness limit of hexane are the causes why a resi-due of hexane in the seed cake after distilling off causes threat of explosion.
These features significantly affect the techno-logy of particular stages of the transport chain, determining their course and efficiency.
According to IMDG Code soybean seed cake should be carried in dry spaces away from heat sources and so trimmed in the holds as to have no direct contact with heating pipelines and bulkheads in vicinity of the engine room. When the sea vo-yage lasts more than 5 days it is required to carry seed cake in the atmosphere of carbon dioxide or another inert gas. With shorter voyage time surface ventilation is recommended, which is to be stopped if the temperature in the cargo mass exceeds 55°C.
In order to decrease the seed cake’s susceptibi-lity to self-heating, it is necessary to season it before loading, during which process the non-satu-rated fatty acids are oxidised. The time-length of seasoning depends on the content of non-saturated acids in the seed cake.
According to guidebook for ships prepared by PLO [3], the degree of threat to soybean seed cake safe carriage by sea due to self-heating increases in
3 According to IMDG Code, ADR, RID and ADN – UN
Number 1208 is hexane’s identification number. SHIP
UNLOADING (pneumatic facilities, band
conveyers, worm)
ELEWATOR
LOADING OF GRAVITATION (telescopic pipes, band conveyers)
CAR /CARRIAGE
Storehouses of fodder mixing
elevated temperature (above 35°C) and high air humidity, when water vapour can be condensed and the cargo wetted. For this reason during sea trans-port of seed cake there should be measured the temperatures of seed cake, air in the cold, external air and sea water.
A symptom of seed cake’s self-heating is a tem-perature higher than surrounding temtem-perature and its continuous increase. In the case when [3]: the temperature of seed cake equals 35 to 40°C,
there shall be increased the frequency of mea-suring temperature and of direct cargo observa-tions, ventilation by opening the hold’s hatch-ways shall be started and pouring the deck with water shall be applied,
the temperature of seed cake exceeds 55°C and continues to increase, ventilation shall be stopped and inert gas introduced.
From the practice of seed cake marine transport it follows that with the transport lasting [3]:
shorter than 5 days there is no risk of self- -heating,
from 5 to 20 days there is little danger of self- -heating in a degree threatening with self- -ignition,
above 20 days there is high danger of its self- -heating and self-ignition.
An important element in the transport of seed cake is the ventilation of loading spaces aimed at maintaining possibly low temperature and proper humidity with simultaneous precluding of water vapour condensation and moistening of the cargo. The commonly known principle is applied that the hold should be ventilated when the dew-point tem-perature of the air in it is higher than external air. Experimental part
Research was conducted on grain composition of soybean seed cake. Out of natural soybean seed cake particular fractions were separated.
The fraction with particles larger than 3 mm constituted 26.9%, in the range 1.2 – 3 mm – 45%, in the range 0.4 – 1.2 mm – 24% and the fraction with particles smaller than 0.075 mm constituted only 0.6% of the whole. The finest fractions with particles smaller than 0.4 mm totally made up 4%. The fraction with finest particles smaller than 0.075 mm according to PN-74/Z-04097.07 standard is classed as medium dust of microscopic fineness, with size of particles ranging from 60 to 500 µm.
An analysis was made of selected storehouses with regard to environment protection.
Storehouses intended for storing soybean seed cake constitute an integral part of the fodder plant (industrial storehouses) or are located at transport knots (transport storehouses), which include houses located in sea ports. These are closed store-houses, floor or chamber silos.
On the basis of research on storing conditions of soybean seed cake loose in domestic storehouses, which embraced 11 magazines in total, therein 7 port storehouses and 4 storehouses located interior a characteristic of these storehouses can be pre-sented taking into account component capacities, and also specification of this type of containers installed and used for storing seed cake.
Most storehouses are equipped with devices protecting the environment against dusting. At the present level of technology covered belt conveyor flights called “redlers” are applied as basic devices significantly limiting the spreading of dust arising during interior transport, and for removing dust from the atmosphere – “cyclone filters”. All exa-mined storehouses are equipped with redlers, except Ewa elevator in Szczecin. Only one indus-trial and one transport storehouse does not have any cyclone filters (Fig. 2). If follows there from that the degree of atmosphere protection inside indus-trial and transport is similar.
In du stri al st oreh ou ses BTZ EWA SNOP BASENOWA WARTA PORT GDAŃSK OPERATING Gd. M. i SP. SOPOT KRUSZWICA SOYA PROXIAL POMORZE OLVIT TRADE REDL ERS C Y C L ON E F ILTE R S Tra ns po rt st oreh ou ses
Fig. 2. The equipment of storehouses storing soybean seed cake with devices protecting the environment against dusting Rys. 2. Wyposażenie magazynów, przechowujących śrutę sojową w urządzenia zabezpieczające środowisko przed pyle-niem
An analysis of data was made which showed that in all industrial elevators temperature mea-surements were performed automatically and also computer monitored. The humidity of soybean seed cake stored in those elevators is also measured in an automated way, in the case of two industrial eleva-tors this measurement being accompanied by com-puter monitoring (“Proxial Pomorze” and “Olvit Trade”).
In this respect the care of the cargo in transport storehouses is much worse. Temperature measure-ments are done in only three out of seven examined elevators and that by means of portable apparatus. The water content in soybean seed cake is also determined by means of portable measuring instruments.
The time of storing soybean seed cake loose is limited and must not exceed 1 month (PN-77/R-64800). In practice this period is much differenti-ated and changes in the range from 1 to 30 days. In port warehouses the time dispersal of storage is smaller and is contained in the range from 10 to 30 days.
Conclusions
It follows from research conducted that the frac-tion with particle size from 1.2 mm to 3 mm had the highest percentage share in natural soybean seed cake – 45%, fraction with particle size smaller than 0.4 mm, altogether about 4%, and the fraction with the tiniest particles smaller than 0.075 mm had 0.6% of total volume, counted among medium dust of microscopic fineness.
The presence of very fine fractions generally unfavourably affects transport process by caking, suspension of seed cake in silo chambers, decreased porosity, dusting during cargo-handling operations, significantly affecting the protection of human health and the environment. During shifting of soy-bean seed cake inside elevators and in the course of performing such operations as active ventilation and throwing about, there arise large amounts of dust which are suspensions of solid fine particles of seed in the air, with density lying in the explosive-ness range.
In all researched industrial storehouses tempera-ture and water content in soybean seed cake are automatically measured, and besides, these parame-ters are computer monitored.
In port storehouses care of the cargo is on-and- -off and is limited to measurements by means of portable apparatus, which confirms the thesis that
transport storehouses are considered points of short-term waiting for the successive means of transport.
Most analysed storehouses are equipped in de-vices protecting the environment against dusting caused by interior transport of the cargo. The pro-tection degree of the atmosphere inside industrial and transport elevators is similar.
To sum up it should be stated that taking into consideration such elements as: type of storage devices, securing the environment inside elevators against dusting, quality level of the storage process in industrial and transport storehouses are not dif-ferent. This level, on the other hand, is considerably higher in industrial storehouses with respect to automation of temperature and water content mea-surements and in the range of quality factors. References
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Recenzent: prof. dr hab. inż. Zofia Cichoń Uniwersytet Ekonomiczny w Krakowie
