понедельник, 22 августа 2011 г.

The detailed description of process of manufacture of expanded polystyrene.

EPS granules are the polystyrene containing easily boiling a component (pentane). EPS granules represent beaded granulated material which can be delivered the consumer, as passed separation division, and without division into fractions. At use drizzle granulated material the made foam granules of polystyrene have the identical sizes, in case of application, not drizzle granulated material foam polystyrene granules will have considerable divergences of the sizes (0,5-12 mm). Process of foaming EPS of granules can be divided into two stages: 1. Preliminary foaming. 2. Drying (staying) the made foam granules, for their further use.

Activation pentane containing in granules EPS occurs under the influence of water steam. Granules EPS under the influence of steam are softened and start to foam, increasing in volume. Probably multiple to fifty increase in initial volume of granules. Also the bulk weight of granules accordingly changes: For example, from 680gr/l to 14gr/l. For acceleration of process of foaming EPS of a granule move to capacities of a foaming agent by means of the mechanical activator of agitator. Constant circulation of granules at influence of water steam allows as fast as possible and to make foam considerable volumes of a material qualitatively. The size of the made foam material directly depends on temperature and time of influence of water steam, and also speed of rotation and an activator of agitator design.

The description of process of foaming of granules EPS on installations
of software-40 equipped with the built in steam and gas generator.

The initial raw materials (EPS granules) from the account bunker by means of screwing a feeder move in the bottom part of a foaming agent. Changing quantity of a submitted material (a regulator of the account bunker) the volume of the made foam granules is regulated. Under the influence of water steam the agent (pentane) containing in EPS granules is activated low-boiling. Granules increase in volume, are superseded by not made foam granules submitted screwing a feeder in the bottom part of installation, level of filling of a foaming agent increases. The made foam granules reach an unloading window in the top part of capacity of a foaming agent and get to drying installation.
Changing height curtains an unloading window it is possible to change volume of the made foam granules. The above curtain and raw materials giving screwing a feeder is less than unloading window, the bigger time water steam influences granules EPS and that accordingly more volume and smaller density of the made foam granules. And, on the contrary, at increase in giving of raw materials in installation and the bottom arrangement curtains an unloading window the bulk density of a ready material increases. Foaming EPS of granules in installation occurs at constant hashing of a material by the activator of agitator. Activator blades mix the made foam granules, interfering conglutination and promoting uniform moving of a material to an unloading window of installation, at constant influence of water steam.

Material drying.
The made foam polystyrene contains to 10-15 % of humidity, besides in granules is created discharging owing to condensation of the rests pentane and water steam. It can lead to deformation (compression) of the made foam granules, compression of granules sharply reduces volume of a material and leads to substantial growth of bulk density. Therefore made foam granules EPS are necessary for drying, for stabilization of internal pressure and hardening of external walls of granules. Diffusion penetration of air into cells of the made foam polystyrene gives to a material high indicators of resistance to compression. Speed of absorption of air the made foam granules above at a material of lower bulk density.

Application of pneumonias dynamic drying-conveyor of the made foam polystyrene allows quickly and to lower effectively residual humidity of a material to 6-3 %, simultaneously moving a material in the bunker staying. Careful transportation of the made foam granules in an air stream heated, to temperature 35-40 about With gives, to drying process necessary dynamics and allows to organize continuous giving of a material on a site staying. During passage by the made foam granules of installation of drying together with loss of residual humidity fluidity of a material considerably increases that positively affects on fill in bunkers staying.

Staying made foam granules EPS.
The endurance of a material is necessary for definitive stabilization internal discharging and achievements of indicators of residual humidity EPS of granules at level of 0,5-1 % in bunkers staying. The bunker staying represent an easy welded design with the fixed bag from an air-penetrable fabric. The bunker can be made various volume, usually used the bunker in volume of 20 m 3. The bunker of the given volume are convenient in work and service, allow to place a site staying practically in any suitable premise for these purposes. The bunker staying incorporate the pneumowires uniting knot staying and allowing to create the bunker module of necessary volume. Made foam granules EPS are in the bunker staying about 4-12 hours depending on the size of granules, bulk density and residual humidity. For reduction of time of endurance of a material in the bunker it is recommended to place a site staying indoors with the lowered relative humidity. Considerable reduction of time of endurance can achieve, having applied a method pumping over granules heating an air stream from the bunker in the bunker. Time of endurance EPS of granules in this case is reduced till 2-3 o`clock.

Features of storage granulated material EPS
Granulated material EPS it is delivered to the consumer basically packed in bags-containers in weight of 30-50 kg. At material purchase it is necessary to consider that period of storage EPS of granules in bags should not exceed six months from the moment of manufacturing and packing. The temperature indoors where to be stored raw materials should not rise above +20 о С. The given restrictions are caused by maintenance decrease in granules low-boiling the agent - pentane. However foaming EPS granulated material, for manufacture concrete polystyrene usually to be spent under the single-stage scheme (at manufacturing of sheet polyfoam of two phasic or even three phasic scheme) therefore the maintenance pentane remains sufficient, for one-phasic foaming even on the expiration of 12 months from the moment of manufacture EPS granulated material. Storage warehouses should provide protection packed up granulated material EPS from adverse weather conditions.

Storage of made foam granules EPS.
Made foam granules EPS after alignment of internal pressure have stable enough behaviors as water absorptions and durabilities and can be stored long enough. However at staying granules in bunkers it is necessary to protect them from influence of low temperatures. At low temperature process of drying of a material is sharply slowed down, granules freeze together that negatively affects quality of received granules EPS. The temperature in an industrial premise should not fall more low +8 о С.

Obligatory ventilation industrial and warehouse.
At connection pentane containing in granulat material EPS with air the mix is formed explosive airily-pentane. Airily-pentane the mix is heavier than air, therefore it is necessary to provide ventilation of a site of foaming and staying a material at floor level. Inflow of fresh air is carried out with top. On a roof of an industrial building the ventilating hatches providing sufficient inflow of fresh air should be established. At floor level it is recommended to establish an exhaust fan. Over an unloading window of a foaming agent and a reception mouth of drying it is necessary to establish exhaust umbrellas, for prevention agglomeration pentane (Airily-pentane mixes). The considered scheme of manufacture of made foam granules EPS on the basis of installation of foaming of software-40, allows to receive to 60 m 3 ready materials for an eight-hour labour shift.

Protection of the made foam granules from freezing
It is necessary to protect the bunker for staying granules from influence of the lowest temperatures as it can lead to material freezing, and it is investigatory to loss of the qualities by it. Besides it do not forget that hardly made foam granules easily lose volume at contact to cold air. The temperature should not fall more low 10 ° С.

Use of a waste
Waste represents valuable raw materials, but owing to the overall dimensions cannot be used for this purpose. Therefore it is provided, or crushing of a waste with their subsequent transportation in the bunker staying granules, or repeated broiling in the course of formation of blocks in the ratio from 10 to 20 %.

Manufacture of blocks of polystyrene

The forming unit represents a steel design of a squared shape with double walls, the internal walls punched on all surface for a possibility of receipt of steam. The work cycle of functioning of the forming unit proceeds as follows:
  • Closing of doors
  • Closing of shutters
  • A chamber warming up. At this stage steam for a chamber warming up (this operation is recommended to be made in the beginning of work of each change) moves.
  • Condensate dump. Condensate dump is made by opening draining the valve and the subsequent discharge a condensate.
  • Material loading. The top board opens and the material is loaded into the forming unit in the portions.
  • Tight closing of the forming unit
  • The First giving of steam. Steam moves in chambers, thus the line condensate plum should be necessarily opened. It allows steam to pass through all thickness of a material and simultaneously with discharge a condensate to make forming. The maintenance of a line plum of a condensate abroach allows to carry out pressure stabilization on the value close to atmospheric that in turn provides optimum distribution of steam on all volume of a material.
  • overlapping of a line condensate plum
  • steam Giving. Again steam moves and the unit is deduced on working pressure (roughly 0,5 kg/sm2), on reaching the set size of pressure, are reckoned time provided on stabilization of a material.
  • Material stabilization
  • Opening of a line condensate plum. The line condensate plum opens, and steam condensate merges. Thus internally pressure in the chamber is resulted according to pressure outside of it. Time of opening of a line of dump, is used also as time of cooling of the block.
  • Opening of doors
  • Block extraction. The block is taken from the unit, is weighed and leaves from a working zone. On the expiration of the short-term period of cooling, blocks keep within a warehouse on storages for the period which duration depends on sphere of application of future production which will be made of this material.

Cutting the block on sheets
On end of ripening the block is subject cutting on sheets of a various thickness. For carrying out of these operations installation is used for are sharp. With the help warming up strings in diameter of 0,5 mm. It is carried out it is sharp the block on height from 0 to 400 mm. Presence of insignificant quantity of a smoke is caused by incorrect installation of speed cutting and string temperatures. Speed installations are sharp is defined by density, width cutting and diameter of a string which in this case make 0,5 mm. In immediate proximity from installation it is recommended to hold constantly available fire extinguishers with carbon dioxide.

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