Considerations in General layout of a steel plant
Considerations in General layout of a steel plant
A steel plant layout is a mechanism which involves knowledge of the space requirements for the facilities and also involves their proper arrangement so that continuous and steady movement of the production cycle takes place. The general lay out of a steel plant is very important and need highest of the attention in design and engineering phases of a steel plant since once a steel plant construction is over, the basic nature of its layout cannot be changed till the lifetime of the plant. Any modification in the layout at a later date will not only be difficult but will involve a major capital expenditure. The steel plant performance depends on a large scale on its general lay out. Since the layout mistakes are usually permanent and expensive, therefore it is essential that a lot of efforts of engineering should enter into evolving the most suitable arrangements of the facilities.
Principle and Definition
The layout in a steel plant decides the location of different production facilities and communication facilities between the production facilities. It also involves detailed location of equipment and machinery within a production facility.
Moore has explained plant layout as,” The plan of or the act of planning, an optimum arrangement of facilities, including personnel, operating equipment, storage space, materials handling equipment and all other supporting services along with the design of the best structure to accommodate these facilities”.
According to Riggs the objective of plant layout is, “ The overall objective of plant layout is to design a physical arrangement that most economically meets the required output-quantity and quality.”
As per J L Zundi, “ Plant layout involves allocation of space and arrangement of equipment in such a manner that overall operating costs are minimized.
According to Dr. MN Dastur, “ The general layout of an integrated steelworks is basically an exercise in making a rational arrangement of the main production units, the energy networks and the auxiliary shops, within the limitation of the selected site.”
The general layout of a steel plant is the physical arrangement of its production and supporting facilities such as production shops, equipment, machineries, buildings, road, rail and pipe network etc. layout determines the way in which materials and other inputs (such as people and information etc.) flow through the operation. The layout is to be planned to have smooth technological process flow of materials and utilities with least amount of handling from receipt of raw materials to the dispatch of the finished products. It involves judicious arrangement of all the facilities needed for smooth production. Defective planning of layout at engineering stage will lead to inefficiency, inflexibility, large volumes of inventories and work in progress and high operating costs etc.
In short the overall objective of designer of the steel plant is to design a physical arrangement which meets the requirements of the end product both quality and quantity wise. It involves allocation of necessary space and allocation of plant and facilities in such a manner so as to have most economical production of the desired products.
Planning a good layout in a project
The decision on a layout is of utmost importance since it represents a long term commitment. If the relationship amongst output, area, and the technological process is not optimum it will affect the plant operation for its lifetime. The technical criteria for the design of a good layout are given below:
i) Integration – A layout must integrate of men, materials and equipment and support services in order to get the optimum output of resources.
ii) Utilization of land (space) – A layout should have proper utilization of both horizontal and vertical spaces and height. It should make possible economic use of the plant area
iii) Distance – A good layout will have minimum distances of men and materials for travel. This means that the total distance travel by the men and material should be minimized as much as possible. Further straight line movements should be preferred in a good layout.
iv) Floor – In a good layout the floor is so arranged so as to have the material/finished products movement in forward direction towards the final stage.
v) Coordination – A good layout ensures the entry into and disposal from any department in such manner that it is most convenient to the issuing or receiving departments. The layout should be considered as a whole.
vi) Flexibility – There should be sufficient provision in a layout so that it becomes possible to modify the layout whenever the need arises.
vii) Accessibility – In a good layout all servicing and maintenance points should be readily accessible. It should facilitate plant and equipment maintenance. For example; equipment should not be placed against a wall because necessary servicing or maintenance cannot be carried out easily.
viii) Safety – In a good layout due consideration to industrial safety methods is necessary. It should provide safety not only to the work process but also to the men. Care must be taken not only of the persons operating the equipment, but also of the visitors to the plant.
ix) Handling – A good layout should reduce the material handling to the minimum. Material handling affects time of operation and cost.
Other basic principles based on which a good layout is made are as follows.
- It should facilitate production process and should meet operational needs
- It should facilitate smooth receipt of raw materials, store materials and smooth dispatch of end products. It should also facilitate the smooth flow and storage of intermediate products
- It should allow flexibility in operation
- It should help in a smooth technological flow for the production process
- It should provide convenience and comfort to the employees at their work place
- It should allow smooth flow of material and processes
- It should help in improvement in labour efficiency, supervision and control
- It should meet the statutory requirements
- It should have sufficient space to take care of future expansion.
- It should help in minimizing both Capital and Operation cost of the plant
The following principles also are to be taken in to account when planning for a good plant layout;
- The geographical limitations of the site;
- Interaction with existing or planned facilities on site such as existing roadways, drainage and utilities routings;
- Interaction with other plants on site;
- The need for plant operability and maintainability;
- The need to locate hazardous materials facilities as far as possible from site boundaries and people living in the local neighborhood;
- The need to prevent confinement where release of flammable substances may occur;
- The need to provide access for emergency services;
- The need to provide emergency escape routes for on-site personnel;
- The need to provide acceptable working conditions for operators.
In practice ideal conditions are not available always and some compromises need to be made. Hence always an optimum layout is made which meets most of the requirements of an ideal layout. For developing a proper layout a designer should have the following information.
- Limitations associated with site
- Site map showing external roads, neighborhood and Land boundary. A typical site map is shown in Fig.1.
- Soil characteristics and contour map of the site showing levels
- Location of the availability of water, power and other utilities
- Alignment of the external railway system and the direction of the incoming and the outgoing traffic. Basic knowledge of selected technology, process, plant and equipment
- The plant capacities and planned future expansion
- Statutory requirements
Fig 1 Typical site map
A layout (Typical shown in Fig.2) normally undergoes a series of revisions from the time it is first made and the last foundation is poured. Even so the ‘final layout’ is necessarily a compromise between the desire to fulfill the criteria given above and the limitations imposed by several other factors. But when the designer has had the conceptual vision to look beyond the present need and immediate difficulties then the resultant layout has the logic and flexibility as well as the capability to give much needed operational performance of the plant in spite of the changed conditions.
Fig.2 Typical general layout of a steel plant