The economic construction and operation of a process unit will depend on how well the plant equipment specified on the process flow sheet and laid out. Plant layout for the plant will consist of the process units involved, which is located in the main plant and other auxiliary buildings. The layout, which refers to each department, must be arranged in order to maximize efficiency and minimize the cost of ownership and plant operating; and also to minimize the time spent by personnel in travelling between buildings.
The principal factors to be considered when designing the plant are:
1. Economic consideration: construction and operation cost.
2. The process requirement 3. Convenience of operation 4. Convenience of maintenance 5. Safety
6. Future expansion
Other than the lists above, it is also advisable to check up the insurance regulations from the view of getting the best coverage at minimum cost for plant building and inventory. The auxiliary buildings and services required on site, in addition to the main processing units (buildings), will include:
i. Storages for raw material and products : Tank farms and Ware house ii. Maintenance workshops.
iii. Store for maintenance and operating supplies.
iv. Control room.
v. Laboratories for process control.
vi. Fire stations and other emergency services.
vii. Utilities: steam boilers, compressed air, power generation, transformer station.
viii. Effluent disposal plant.
ix. Offices for general administration.
x. Canteens, surau and other amenity buildings, such as medical centres.
xi. Car parks.
xii. Guard house / security posts.
1. Costs
- The cost required to build a plant need to be kept at possible minimum value so that less modal will be used and more profits will be generated. The cost of construction can be minimized by choosing a land site with cheapest price but has a good facilities and utilities provided. Other than that, the layout needs to have the shortest run of connecting pipes between all equipment and also least amount of structural steel work. However, this will not necessarily be the best arrangement for operation and maintenance. In plant layout, economic is considered mainly with steelwork, concrete, piping and electric cabling.
2. Process Requirement
- All the required equipment need to be placed properly and strategically so that can achieves smooth flow for transportation from raw materials to final product storage. The installation of the auxiliaries also need to be placed in such was so that it will occupy the least space. Process units are normally spaced at least 30 meters apart.
Administration offices and laboratories, in which a relatively large number people will be working, should be located well away from potentially hazardous process control rooms. The siting of the main process units will determine the layout of the plant roads, pipes, alleys and drains. Access roads will also be constructed for operation and maintenance purpose. Utility building should be sited to give the most economical run of the processing units. The main storage areas should be placed between the loading and unloading facilities and the process units they serve. Storage tanks containing hazardous materials should be sited at a safe distance from other buildings which is at least 70 meter from site boundary.
3. Operation
- Any equipment that required frequent operation should be located near to the control room so that easier for the operators to monitor the operation. All valves,
4. Maintenance
- All equipment needs to be prepared with maintenance facilities so that if any problems arise during the process, the source of problem will be detected and solved at a fast rate. Heat exchangers need to be sited so that the tube bundles can be easily withdrawn for cleaning and tube replacement. Vessels that require frequent replacement of catalyst or packing should be located on the outside of buildings.
Equipment that requires dismantling for maintenance, such as compressors and large pumps, should be placed under cover.
5. Safety
- Since most chemicals are hazardous and have the potential to explode in wrong condition, blast walls may need to be built in order to separate potentially hazardous equipment and thus confine the effects of an explosion. Other than that, at least two escape routes for operator must be provided from each level in the process building and assembly point need to be built at an easy access and the emergency route need to be stated clearly.
6. Plant Expansion
- Equipment should be located so that it can be conveniently tied in with any future expansion of the process. Space should be left on pipe alleys for future needs, and service pipes should be over-sized to allow for future requirements. Free space for plant expansion is important so that if the production rate need to be increased, more equipment should be added to the plant, thus free space will allow future expansion to be able to accommodate the equipment required. This expansion space is also very important because the additions of equipment and pipes can be erected and tested with the minimum interference to plant operations.
Plant Layout Description
As mentioned in the site selection section, the plant was decided to be built in Gebeng Industrial Estate, Kuantan, Pahang that was estimated to cover about 10 hectares of industrial lot ready land with price of RM16.00 per square feet.
Gebeng is located in Pahang in the East coast of Malaysia. Every year Pahang experiencing Northeast Monsoon that brings rain and wind. Thus, the structure of the plant is placed in
upwind direction. The buildings need to be placed in such that the wind will not affect the plant and brings any inconvenience. Strategic placement of the buildings relative to wind direction can assist to cool down process equipment during the process.
By referring to the plant layout provided in the following figure, administration building is the main and most visited building for many purposes in a plant. It should be located on the public and safe side of security point and as close as possible to main entrance.
Administration offices and laboratories, in which a relatively large number of people will be working, are located well an away from potentially hazardous process which is the main processing plant. Stores for maintenance and operating supplies was placed near to the administration buildings so that the staff will have easy access to the service.
There is a bottom expansion just below the main process plant and near to the waste treatment plant. This free space is provided to be used for the placement of new equipment and pipes in the future just in case the plant needs to be expanded. The waste treatment plant will enable the direct transport of waste stream produced by the separation units. There is also a pond that is placed next to the waste treatment plant.
Waste treatment plant, utilities plant and tank farm were placed near to the main process plant. This placement also reduces the distance and length of supply pipes used in the transporting process of raw materials, waste, and utilities to or from the plant area, making it cost effective. Beside it, it should be beside a road which will make it easier for loading and unloading of materials.
Control room was placed near to the main processing plant so that easier for the operators to monitor the operation of the plant because if the is malfunction in any of the operating process, troops can be send to the site immediately.
Maintenance workshops and others that did not link to process materials should be located together at the safe area and within easy access to process units. Direct access should be provided for traffic purposes, which if possible should not pass through any process area.
There is also a loading area placed for transport of goods and raw materials where only the lorries and other form of transport to transfer these materials allowed entering the area.
Canteen and surau (prayer room) are also provided for the convenience of the staffs and were placed near to the administration and maintenance workshop buildings because it is one of the most used workplace and it is a must to have easy access to these places. These buildings
should be located in a safe area within a short distance of the main concentration of workers.
The surrounding should be attractive and relaxing for workers to release some stress from hectic workloads.
For quality control of products, a plant needs a laboratory to inspect the products produced.
Work laboratories should be located at a safe area near the administration building where most facilities are completed. Clinic is placed next to the laboratory to handle any emergency case caused by chemicals. Fire house to handle emergency cases for example fire or explosion of the plant is built near to the main processing plant.
Sufficient car parks facilities also provided for the convenience of the staff and personnel or visitors to park their vehicles. Car parks are placed near to the main entrance to prevent any unwanted hazard to the properties.
Guard houses or security post were placed at both entrances to the plant to monitor the flow of in and out to the plant itself. There were three assembly point placed near to every section of the plant so that in case of emergency, all the people in the site can be evacuated at faster rate to these safer places.
Other than those mentioned above, free lands also available at the plant layout for future needs. Trees also will be planted in the site to absorb the emission of carbon dioxide gases and also to make the site pleasant to the eye. There is no smoking area provided in this plant layout since chlorobenzene is volatile and explosive to ignition of fire, thus for safety of the plant and all personnel, smoking in the plant area are strictly prohibited. Access road will be needed to each building for construction and for operation and maintenance.
General Safety Procedures
For a new plant, it is very important to have sufficient site medical, fire and security services.
For ensuring safety, health and welfare of all workers at the plant, Occupational Safety and Health Act (OSHA) was enacted. All contractors, employees and agents must tolerate and understand the Site Safety Rules & Regulations before starting any work. Work cannot begin until a complete site safety induction has been carried out. Safety is the most pressing issue when being evaluated in a chemical plant. It must be made the highest priority as compared to other factors such as profit. Prevention wills the best means of containing risk and danger.
The plant risk reduction must be followed as strictly as possible to ensure all precautions are taken.
Some general manuals that should be followed to ensure the safety in work field and work force are listed below:
1. Each employee is expected to know and observe all plant safety procedure. All injuries, no matter how light, must be reported to the immediate Supervisor. This is to ensure the protection of each worker and assure that proper records of the accidents are made.
2. All employees are responsible for their colleagues and of their own. Broken equipment, unsafe conditions and unsafe practices must be reported to Supervisor as soon as discovered.
3. There shall be no smoking at any time within the plant area since most of the chemicals are volatile. Matches or lighters shall not be carried into the plant and must be left in locker rooms.
4. It is mandatory that all workers at the plant area to wear hard hats and safety glasses all the time. In some plant area, other protection may be required such as hearing protection. Person who do not wear this safety equipment are prohibited to enter the plant area.
5. Possession or use of liquor and illegal drugs is not permitted on the plant premises.
Anyone under the influenced of either will is strictly prohibited from entering the premises.
6. Visitor must apply permission at the main office or at the security post, sign a release, and be instructed of plant safety rules before they are allowed to enter the plant.
Visitor will not be taken into the plant areas that are experiencing production problems. Any visitors who do not possess the temporary entering pass cannot be around the plant site.
7. All workers must know how to use all types of fire extinguishers, fire hoses, fire blankets, and other personal protective equipment. (e.g. water must not be used on fires around the electrical equipment since water is a conductor that may result an electrocution of people).
Figure 1: Plant Layout