水產養殖用氧氣錐溶氧效率之基礎研究

Abstract

本研究首先針對養殖池上水柱噴射方式進行曝氣試驗探討。經試驗結果顯 示，水柱流量0.24m3/min、水溫28.7℃時之曝氣，養殖池有最大的增氧速 率，其總輸氧係數達0.0261 1/min，然其溶氧量皆在6 mg/L以下，獲致水 柱曝氣裝置對於養殖池溶氧量的提高有其限制。因此本研究另針對氧氣錐 增氧進行探討，經測試結果利用氧氣錐增氧可使養殖池內的溶氧值提高至 過飽和的狀態，這對自動化超集約養殖之氧氣供應有其重要性。以鰻魚養 殖密度為37.3kg/ton of water，氧氣錐在不同的純氧輸入壓力下，對於 養殖池水溶氧值的提高並無明顯差異。入水流量0.3m3/min(即池中單位水 體積之流率為5.9×10-4CMM/m3)與氧消耗率為10.62mg/m3．min時對於養 殖池水溶氧值的提高有最好的效果，但在此高入水流量時，導致養殖池水 位控制不易。故本研究獲致入水流量0.225m3/min、純氧輸入壓力0.1kg/ cm2為氧氣錐操作之最適條件。同時由牛頓冷卻定律所建立的方程式，對 於本研究之輸氧與耗氧模式甚為適用，可用來預測輸、耗氧過程中，養殖 池溶氧值的變化。

In this research, the areation of an aquacultural tank using a waterjet areator is first investigated. The testing results show that underthe condition of the water jet flow rate 0.24m3/min with watertemperature 28.7℃, the Dissolved Oxygen (DO) of the aquaculturaltank can achieve the maximum rate of oxygen increase with the overallcoefficient for oxygen transfer 0.0261 1/min. However, a restriction of the water jet areator to increase the DO content is occurred in thisstudy and the maximum value of DO can be obtained only up to 6 mg/L. Therefore, the use of an oxygen cone to dissolve oxygen into the wateris also studied. The experimental results show that using the oxygen cone the DO content can be raised to a super-saturated state. It is veryimportant for the oxygen supply of an automatic superintensive waterreuse cultural system.With the eel stocking density 37.3kg/ton of water, there are noobvious effects for the increasing rate of DO content of the waterin the aquacultural tank as the pure oxygen inlet pressures varied. The water in the aquacultural tank has the best dissolution efficiency of increasing DO content when the inlet water flow rate is 0.3m3/ min (the water flow rate per unit volume of water in tank is 5.9×10-4CMM/m3)and the oxygen consuming rate per unit volume of water in the tank is 10.62mg/m3．min. However, the water level of the tank in the recirculationsystem is hard to control under such high inlet water flow rate.The optimal condition with the inlet water flow rate 0.225m3/min and the pure oxygen inlet pressure 0.1kg/cm2, is obtained for the operationof the oxygen cone. The model with the equation constructed by Newton'slaw of cooling is also valid for this study either for the importing or consuming process of oxygen transfer. It can be used to predict thechange of DO content of water in the aquacultural tank during theimporting and consuming process.