investment in new transformers, circuit breakers, and feeders. Due to the lead time required for procuring the hardware, this project was phased over three years. The cost of the project was high, but so were the expected returns. We expected to reduce the value of lost production due to electrical supply problems by 50–60%, giving a benefit-to-cost ratio of 5:1.
A different issue related to the cost of electricity purchased from the public supply system. The electricity supplier applied a three-part tariff, with charges for the connected load (kW), energy consumed (kWhrs), and a surcharge for power factor below 0.96 (kVA charge). In addition to the thousands of induction motors in service, there were large induction furnaces in the factory. Without correction, the power factor could drop as low as 0.91. We already had a number of power factor correction capacitor banks, which brought it up to 0.94–0.95. We planned a separate project to increase the power factor to a maximum of 0.98. This upper limit was set by the possibility of a large induction furnace trip when we could end up with a leading power factor. The new capacitor banks would be brought into service or disconnected so that the power factor never exceeded 0.98 or went below 0.96. The project was phased over two years, based on hardware availability. The costs were relatively low and the expected benefit-to-cost ratio was 5:1.
3.Air Supply
There were two problems, one relating to pressure fluctuations and the other to entrained water. The latter issue had been so serious in the past that the main air supply lines in the factory buildings were sloped in a saw-tooth fashion, with manual drains at the low points (see Figure 3.1).
Pressure fluctuations were due to peak demands exceeding installed capacity and because of pressure drops in the pipelines. The entrained water came from the humid air. The water should have condensed in the after coolers of the air compressors, but a simple calculation showed that the cooling water temperature was far too high to be effective. In turn, this was due to an overload on the closed circuit cooling system. The original cooling pond was suitable for two diesel engines and three air compressors. The equipment numbers had grown to four diesel engines and four compressors. One more generator and two compressors were on order.
Figure 3.1 Original design of 4” air mains.
The air compression capacity was marginal and the projected demand increase was 30 percent. We decided that a third one would be needed to provide buffer capacity. In order to reduce the pressure drop in the pipeline distribution network, we planned to add four new air receivers located close to the main consumers. Peak demands could then be met from these receivers. They would also act as additional knock-out vessels to trap entrained water.
We planned to install industrial cooling towers to absorb heat from the cooling water used in the engine and compressor cooling jackets and after-coolers. This would eliminate the bulk of the entrained water at source.
These two projects were planned for completion in 18 months. The cost of the third compressor, air receivers, and cooling towers was in the medium-range. We expected to reduce the value of lost production due to air supply problems by 90%, giving a benefit-to-cost ratio of 15: 1.
4.Water Supply
The city municipal water supply system provided about 70% of the factory’s requirements. The company had installed many bore wells to draw groundwater to meet the remaining requirements. The city accepted our justification for requesting additional water supply, but were not willing to invest in a new pipeline from an existing reservoir about four miles away. We offered to underwrite the capital costs while the ownership remained with the municipality. I convinced the finance manager that we should pay a grant towards the capital cost of a city asset that would benefit the company.
We also decided to accelerate investment in additional bore wells in plots of land owned by the company in the vicinity of the existing factory site.
These projects were also in the medium-range of costs. Most of the additional water requirements were for welfare facilities. Without these projects, production levels would eventually have to be drastically curtailed, but we justified the project on staff welfare and HSE grounds.
5.Dust and Fume Pollution
The dust pollution in the ceramics department and the fume problem in the plating department were potentially serious health issues. The existing extraction systems were clearly not effective, but the solutions were not obvious. At this stage, the project scope was to study the problem carefully, understand the causes, and identify solutions. We employed a specialist consultant to assist us, and the work took several months to complete. The problem was traced to the particle size of the ceramic dust. These were so small that much higher velocities were required at the extraction unit inlets. The project scope included the installation of cyclone separators and powerful extractor fans.
At the plating department, we found that the fume extraction issue was more complex. The extraction hoods had to be redesigned and repositioned. Extraction velocities had to be increased, so new fans were required.
The costs of these two projects were in the medium range, and the lead time of the equipment required meant that the project had to be scheduled in the third year. We justified it as an HSE project, but the results showed that there were other benefits as well.
6.Security of Energy Supply to the Canteen
The scale of the problems that the canteen faced on a daily basis was staggering. The local culture required that freshly cooked and piping hot food be served. The main staple was cooked rice, of which we needed on average, 10 oz. per employee. About 1500 meals were served in each batch.
The rice was cooked in large electrically-heated cookers mounted on trunnions. Each batch had to be cooked in 20 minutes, and the vessel cleaned and ready for the next batch in 5–10 minutes. The water temperature had to be raised from the ambient 60–70°F to 212°F, and this could take 10–12 minutes. The canteen manager was visibly under stress. If there was any glitch, food could not be served—to at least 1500 and possibly up to 4500 waiting people!
The electrical cooking system was excellent, but consumed significant amounts of energy. Because sunshine was available in plenty, we planned to install solar water heater panels on the concrete roof of the canteen. Each panel would be about 120 square feet in area. With four of them in series, even on a cloudy day we could get the water to 150–160°F in about 10 minutes. We decided to install two banks of four panels each along with an insulated hot water storage tank. This allowed us to supply hot water rapidly, and stored enough water for the second and third shifts as well. A structural design check of the roof confirmed that it was suitable for the additional roof loads.
The project costs were in the medium range. Delivery of the solar panels would take 6–8 months, so we phased the project into the second year. The primary purpose was to get rapid supplies of fairly hot water to the cooking vessels, so that cycle time could be reduced. This would give recovery time to the canteen staff in the event of a power supply glitch. The bonus was that electrical energy savings made it economical as well. The project was justified as a welfare item.
3.4 Results
We completed all the selected projects within three years. When computing benefit-to-cost ratios, we measured or estimated the benefits over a 3-year period (thereafter, they would be influenced by other initiatives as well). The results are described below.
1.Factory Ventilation (HSE)
The air circulation fans were installed more or less on schedule. Some installations were late, caused by delivery delays from
