การออกแบบเบื้องต้นของเครื่องจักรในการทำความสะอาดแท่นรับส่งคอนกรีตมวลเบาและการวิเคราะห์ความเหมาะสมทางเทคนิคและเศรษฐศาสตร์

Abstract

The purpose of this study was to determine the appropriate cleaning method for autoclave platform in aerated concrete production process in order to reduce the amount of non-conforming products. The machines for two cleaning processes of brush polishing and sand blasting were designed and the prototype machines were tested their performance. It was found that both cleaning machines could clean up to 96 percent of all the dust which conforming to the required standard. The hypothesis testing of the amount of dust removed from the two cleaning methods together with the dust collectors were tested under 5 percent significant level and it was found that the performance of the dust removing of the two methods were equivalent. The economic analysis was based on 10 years period, at the minimum attracting rate of return of 15 percent and at the polishing 400 platforms. It was found that the polishing method was better than the sand blasting method due to the net present value of the cash flow after tax of the polishing method was more than the sand blasting method. The incremental investment analysis was used to compare the polishing method with the outsource cleaning company. It was found that the internal rate of return of the incremental cash flow after tax was at 269 percent, which was higher than the minimum attractive rate of return. Sensitivity analysis of the changing of the main parameters in the range of -/+50 percentwere found less effect to investment decision. And the break-even point was at not less than 60 platforms or only 15 percent of the production capacity. In conclusion, the polishing method for cleaning the aerated concrete platform was found technically and economically feasible for investment.