Cold Link Africa July/August 2019 - Page 29

FEATURE INCORPORATING COLD CHAIN • • in the systems. HFCs are costly and the refrigerant used on sites every year is truly alarming. Minimising downtime that would result in stock losses. Refrigeration systems normally give you warning signals prior to a failure. If you do planned servicing, you can hopefully pick this up and take corrective actions. Keeping records. R717 systems have very strict safety precautions that need to be complied with at all times. Records need to be kept on site of components that require re- certification every 36 months. ENERGY EFFICIENCY Ammonia plants (such as this one at Go Chill) are a popular choice for cold storage refrigeration solutions. Moodley. “The biggest headache is ensuring that everyone gets out safely during an emergency evacuation,” he says. “But if the services are done monthly, there are no major issues with the plant besides a few minor trips that are identified and resolved by our temperature team.” LOOKING AT MAINTENANCE A refrigeration system (usually) works 24 hours a day. If you drove a car at 100km/h for 24 hours a day, then you would cover ± 70 000km per month. This gives an indication of how hard a compressor works and the need to maintain it before it breaks down, Van der Merwe explains. “Planned maintenance is critical to ensure the plant operates reliably and at peak efficiency.” According to Ford, it’s key that service contacts are put in place to maintain the system, ensuring maximum efficiency and preventing any chance of major breakdowns that could cause stock or product loss. “It is important to note that operation costs can increase due to unmaintained systems.” Maintenance is an ongoing process and aims to prolong plant life and reduce down-time resulting from breakdowns,” explains Smith. The maintenance programme should, among other duties, include leak checking, oil changes, filter changes, and condenser/evaporator cleaning, he advises. Mechanical and electrical checks must also be conducted so that worn parts can be replaced. “In doing regular maintenance, you can prevent major problems in the plant in the future,” says Ford. Other than regular maintenance, a more comprehensive service and maintenance plan will be needed to keep the plant running optimally after it reaches a certain age. “A plan should be put in place for the life span expected of the plant, to keep it running at its best capacity throughout its cycle.” If you consider the value of product that is being stored in a freezer store, the potential loss of product, and the implications of finding alternative storage costs at short notice, then it is a better bet to carry out the scheduled maintenance, Van der Merwe says. “Scheduled maintenance is generally a predictable cost with reliable operation at expected temperatures as opposed to running until the equipment fails and then scrambling to sort out the problems and potentially dumping spoiled product.” Moodley explains that at their cold store, maintenance is done monthly. Condensers, drip trays and plant rooms are cleaned. Oil is drained from the system. The system is checked for leaks, rust and corrosion. Water is tested for pH value. “All of this is done to ensure that the plant is kept healthy at all times and we don’t encounter problems during our steri- cooling cycles.” “Planned maintenance would offer the facility owners a more predictable operational life,” agrees La Grange. Here are some tips he considers important: • Having qualified technicians with the required South African Qualification and Certification Committee for Gas (SAQCC Gas) licence attending to any installation containing a refrigerant. Should you have a R717 installation, additional training and testing is required as part of the maintenance staff’s SAQCC gas licence. This requires additional training and re-testing every three years to remain current. • Having extensive commissioning information to refer to. Commissioning a system is important to confirm that the design was done correctly and accurately. It’s also for defining the system’s correct operating conditions. It’s very important that the system’s refrigerant is recorded for future reference. The commissioning data would also contain crucial details regarding operational settings to achieve optimal operational efficiency. • Minimising leakage rates and doing regular checks to keep the refrigerant COLD LINK AFRICA • July/August 2019 “Energy saving has become very important for all users of refrigeration of late,” says Smith. Energy saving comes at a cost and the more energy saving devices or systems added, the greater the CAPEX cost. “Energy saving comes from efficient design and the use of energy efficient alternatives when selecting your equipment.” First cost is generally a once-off cost if the correct equipment is supplied and installed, explains Van der Merwe. “It is accepted that it costs more to install a system with a higher efficiency but it is money well spent and it will pay for itself.” Running costs are incurred on a continuous basis for the entire life of the plant and this quickly outweighs any capital cost savings if you install a low cost system with high running costs. Electrical costs will increase annually so this cost portion will only get worse. “Energy efficiency is a very big, if not the biggest, deciding factor of big installations,” says La Grange. If one reviews the TEWI formula (the indirect global warming factors), the weighting of energy consumed is especially heavy in South Africa, due to the widespread use of coal to generate the overwhelming majority of the country’s energy needs. Adding a renewable source like solar has been applied very successfully to reduce the load from the national grid and in doing so, installations’ TEWI index is dramatically reduced, says La Grange. “Using green alternatives as refrigerants reduced the warming impact but the biggest impact is still the pollution resulting from energy required to operate the facility.” In South Africa, our electrical energy is for the greater part generated by burning coal. The weighting of energy generated from coal has a dramatic effect on the calculations. At an average of around 1 075gCO 2 /kWh of electricity generated by burning coal, it compares very poorly with an average of 155gCO/kWh from 29