Engineering Mathematics  Control Systems  Control of FlowTransport System of Concrete Mixing Plants  Structural Analysis
Structural analysis of the transport scheme
The concrete mixing plants facilities on construction of large industrial objects represents the complex technological system consisting of a
network of conveyor lines, storehouses concrete aggregates, departments of control screening, heatingcooling, dehydration, account bunkers.
Two versions of technological schemes of supply of materials by conveyor transport from storehouses to account bunkers of concrete plants are
possible (Fig.1).
Fig.1. Basic schemes of conveyor transport.
1 – storehouses; 2 – a conveyor; 3 – bunkers; 4 – the main conveyor.
In the first case (Fig.1, a) the materials coming from a storehouse or from group of storehouses, move to account bunkers by system of
tape conveyors, and for this scheme availability of the main conveyor uniting all flows of materials is characteristic. In the second case (Fig.1,
b) the materials coming from storehouses, are not united in one flow, that is the main conveyor is absent.
Fig.2. Possible versions of transport routes.
m_{1} – m_{7} – routes; 1 – 35 – conveyors.
Route – the sequence of conveyors (Fig.2), transporting materials from same storehouse (for example,
m_{1} = {1, 2, 3, 4, 5, 6, 7}; m_{2} ={8, 3, 9, 10}).
Intersection of routes – the conveyor or group of conveyors entering in some routes (for example, 3, 6, 23).
Union of routes – the set of all routes having the given intersection (for example, m_{1} U m_{2};
m_{1} U m_{3}; m_{5} U m_{6} U m_{7}).
Connection – the route entering at the same time in some unions (for example, m_{1}; m_{3}).
Network – the set of unions of routes, constructed thus that for any union at least, one union (distinct from the given), having with it
connection, will be (Fig.2, а).
Junction – the union of routes which is not having connections with other unions (Fig.2, б).
The general scheme of conveyor transport may be divided into subschemes which structure conforms either to unit (Fig.1, а), or to network
(Fig.1, б).
The accepted definitions we'll use at the structurel analysis of the actual scheme of conveyor transport (Fig.3).
Fig.3. The actual scheme of conveyor lines of concrete mixing plants facilities.
According this scheme aggregates of concrete (sand, gravel, road metal) various fractions move from storehouses C_{i} by conveyor
lines k_{l} to concrete plants of cyclic (I) and continuous (II) action. In points A_{j} and
B_{j} flowss of materials are accordingly divided or united. The initial information about structure of the considered transport
scheme is shown in tab.1.
Two basic versions of the technological scheme are possible: the first – with supply on a plant of cyclic action only gravel; the second – with
supply on this plant road metal, and gravel too.
The scheme (Fig.3) and tab.1 provide a possibility of use of road metal at a plant of cyclic action as a aggregate for some marks of concrete. The
structural analysis of the transport scheme we'll execute for its first version.
To establish interconnection between separate routes, we'll draw up on the basis of tab.1 the following matrix S :
The matrix is constructed as follows. If on intersection of the lth line and the jth column of the matrix 1 is it means,
that the lth conveyor line enters into the jth route, otherwise the ljth element of the matrix S is equal
to 0.
Let's consider the matrix S structure in greater detail. The conveyor k_{1} enters only into the route m_{9},
therefore the ninth element of the first line is equal 1, and other elements – zeros. On the other hand, the route m_{2} consists
of conveyor lines k_{4}, k_{5}, k_{6}. In the matrix S it is shown that the fourth,
fifth and sixth elements of the second column are equal to 1.
Using the matrix S, we define intersections, unions of routes and connections. If in the lth line of the matrix S,
appropriating to the conveyor line k_{l}, two or more unit elements are available the given conveyor line is intersection of those
routes which columns are conformed with these elements. For example, the conveyor line k_{4} is an intersection of the routes
m_{1}, m_{2}, m_{3}, m_{4}, and the conveyor line k_{6} is an
intersection of the routesm_{2}, m_{4}, m_{6}, m_{8}. Conveyors k_{l}
and k_{2} also can be considered as an intersection, as enter into the isolated route m_{9}.
The set of the routes u_{2} = m_{1} U m_{2} U m_{3} U m_{4} is
a union of routes on the intersection k_{4}, the set of the routes u_{3} = m_{2} U
m_{4} U m_{6} U m_{8} – a union of routes on the intersection k_{6}, etc.
For the union u_{3} all its four consisting routes – connections: m_{2} and m_{4} enter into the
unions u_{2} and u_{3}; m_{6}  into u_{3} and u_{5};
m_{8} – into u_{3} and u_{9} (tab.2).
Analyzing connections m_{k}, we come to conclusion, that all routes of the transport scheme are divided on three sets not connected
among themselves: 1 – unit (route m_{9}); 2 – network (routes m_{1}, m_{2}, ..., m_{8});
3 – a network (routes m_{10}, m_{11}, m_{12}, m_{13}).
Fig.4. Technologically independent sites of the transport scheme.
In the actual transport scheme it conforms to breakdown of the scheme on technologically independent three sites (Fig.4): transportation of gravel
of fraction 80  120 mm  unit (Fig.4, a); transportation of gravel of fractions 5  10, 10  20, 20  40 and 40  80 mm  network (Fig.4,
b); transportation of sand  network (Fig.4, c).
The control by transport flows of aggregate to account bunkers on three received sites can be carried out independently.
