Plant Maintenance

Tracking belts on bucket elevators and short belt conveyors. Flexible, flat belts are used on bucket elevators and belt conveyors to carry loose, bulk product. The belt is stretched tight from head drum to tail drum and the friction generated on the turning head drum is used to drive the belt and carry the product. The belt must run true on the end pulleys (drums) and stay within the sides of the equipment structure. If the belt runs off the drums, buckets will be destroyed and belt edges frayed. In the worst cases the belt runs off the pulleys resulting in a breakdown repair. Proper and long- lived tracking of belts is critical for trouble-free operation. [Read more…]

Bag house dust bag selection. The dust bags within a bag house must handle the process conditions they experience. The choice of bag materials is usually based on the cheapest fabric that will handle the conditions for a minimum of 3 to 5 years’ operation. The selection of the bag materials requires a good understanding of the process temperature, moisture content, chemical reactions with the bag fibre, dust loading effects and behaviour of the dust bags in operation. [Read more…]

One method to clean particles from a liquid or gas is to pass it through a filter. The filter is a screen that traps and holds the contaminants on its surface while allowing the fluid to twist its way past the build-up and screen. The screen can be used until the back- pressure from the collected contaminants choke it so severely that the fluid flow falls drastically. At that point the screen must be cleaned. This article explains how membrane and leaf filtration processes work and the critical factors that produce successful filtration results. [Read more…]

In some process situations, mechanical level sensors are the best choice for the environment or are stipulated by law (as in boilers). To operate these devices requires the physical contact of the process being measured. They provide solid indisputable proof that a process condition has been achieved. Provided the mechanical mechanism is connected and working properly, these devices provide the most believable proof that a level in a vessel, tank or silo is actually what the instrument is saying it is. [Read more…]

A computerised maintenance management system (CMMS) is the maintenance department’s most important tool. It provides insight into the behaviour of the facility’s individual assets, i.e. the plant and equipment. For a CMMS to be of use it must be used as an information ‘bank’ that can be investigated. There are 9 really good reasons to use a CMMS. And each one of them alone makes a CMMS worth having. [Read more…]

When oil in gearboxes become contaminated there is a rapid loss of bearing operating life. It is critical that metal particles, dirt, sand, oxidisation products, etc be removed from the oil before they gouge and tear-up the finely toleranced machine parts. Oil replacement, contamination prevention and oil filtration are common practices religiously adopted by the best in the equipment reliability management business. This article explains the fine requirements for successful contamination control to insure long trouble- free equipment life. [Read more…]

Steam boilers not used for power generation and of smaller size and energy output are termed packaged boilers. The heat source is usually either electric coils or a burning fuel. When a flame is used to heat the water it is known as a fired packaged boiler. Fired boilers are considered efficient steam generators with about 85% of the available energy converted to steam. They can be of water-tube or fire-tube design. Boilers incorporate many key aspects of heat transfer to create steam from water. This article describes how fired boilers work and their key components. [Read more…]

Heat is energy and its nature is to flow from a state of high excitement to one of low excitement. Heat is transferred from a hot place to a cold place by convection, conduction or radiation. This article explains the three modes of heat transfer and provides simple examples of each. Methods to reduce and increase heat transfer are also presented. [Read more…]

The electrical conductivity (and its opposite, resistivity) of water based solutions indicate its electrical current carrying ability. High conductivity occurs when many charged atoms and ions are in the water. This typically means the presence of dissolved metals, salts, acidic or alkali chemicals. Conductivity probes are used to measure the total level of charged particles present. This article explains how conductivity probes work and their application in boiler water treatment and management. [Read more…]

A spinning pump impeller provides the means to draw incoming product through the pump, energise it, and then force it out under pressure. The impeller coverts the electrical energy from the motor into hydraulic energy of the liquid. It does this by taking the liquid into the center of the impeller and flinging it outward at high speed. To efficiently continue to do this the impeller must remain in the same condition as it was when first installed. If the impeller deteriorates the conversion from electrical to hydraulic energy becomes inefficient. Power is wasted, flow and pressure fall and the pump cannot do its designed duty. [Read more…]

How do you decide what level and type of maintenance to use on an individual item of plant and its sub-assemblies? Not all equipment is equally important to your business. Some are critical to production and without them the process stops. Others are important and will eventually affect production if they cannot be returned to service in time. While other items of plant are not important at all and can fail and not affect production for a very long time. [Read more…]

A belt conveyor is a moving surface used to transport product from one end to the other. In its basic form it consists of a driving head pulley, a tail pulley, the moving belt, support rollers, cleaning devices, tensioning mechanisms and a structural frame. Though simple in concept its many components need to work together as a system to get the best performance and operating life. Critical to that is an understanding of how to care for a belt conveyor and tune it for successful operation. [Read more…]

Moving slurries about. Slurry is solid particles in a liquid. Concentration can vary from mostly liquid to mostly solid. Slurries are usually transported through pipe work using pumps, pressurised gas or steam. Different concentrations and different particulate produce different flow characteristics. Successful slurry transport requires knowledge of the particulate, its transport behaviour in the liquid at different concentrations and speeds, the nature and friction effects of the pipe work system and selection of the right motive method for the application. This article provides information for transporting slurries of up to 60% solids concentration. [Read more…]

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Effect of process changes on electric motors. This article explains the effect of changing process loads on AC induction electric motor performance. The motor’s behaviour is a response to the load imposed on it by the equipment connected to it. The equipment’s behaviour is itself a response to the duty and service it has to perform. Where the equipment duty and service is adjustable by the operator, or fluctuates as the process changes, the motor will react to those changes. When the changes are so excessive that they are beyond the motor’s ability to handle them the motor stops and the equipment or process stops with it. Keywords: squirrel-cage motor, overload. [Read more…]

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The 5 s method of operation – A Five S program focuses on having visual order, organization, cleanliness and standardization throughout the workplace and the operation. It is a structured method to put operators and maintainers in control of what they do. [Read more…]