桩西联采油废水氧化塘去除COD的数学模型

Mathematical Models for Oilfield Produced Water Oxidation Ponds at Zhuangxi Oil Gathering/Water Treating Plant

基于动力学和水力停留时间分布研究结果,研究了带纵向扩散的推流式反应池模型(模型Ⅰ)和完全混合式反应池串连模型(模型Ⅱ)对桩西联合站采油废水氧化塘的适用性。给出了两种数学模型中包含的各参数的数值或表达式,其中包括:扩散准数Pe=0.780,COD降解速率常数K(28.8℃)=0.07175h-1,K值温度系数θ=1.054,COD生化降解率27%,平均水力停留时间tM=75h。2001年7月进行16次测试,得到氧化塘平均出口COD值(CODe)=127.6mg/L(平均水温TM=35.8℃,平均进口COD值169.4mg/L),按模型Ⅰ计算,CODe=126.2mg/L,相对偏差为-1.10%,按模型Ⅱ计算,CODe=126.5mg/L,相对偏差为-0.860%。用模型Ⅰ和Ⅱ计算的2000年12月到2001年8月9个月的月平均CODe值(月平均水温TM在10.9～36.0℃),与平均实测值的相对偏差范围分别为-4.50%～+4.52%和-4.42%～+4.18%,相对偏差平均值分别为+0.453%和+0.581%。这两个数学模型均可用于废水氧化塘的处理结果预测和设计。表2参4。

The applicability of reactor model with axial diffusion (model Ⅰ) and model of continuous flow stirred tank reactors in series (mode Ⅱ) to the produced water oxidation ponds at Zhuangxi oil gathering/water treating plant in Zhuangxi, Shengli, is investigated by using the results of previous dynamical study and study on hydraulic residence time distribution. The values or expressions for calculating the parameters contained in these mathematical models are presented, including diffusion criterium Pe=0.780, COD degradation rate constant k(28.8℃)=0.071 5 h^(-1), temperature coefficient of k value θ=1.054, percent of biochemical degradation of COD 27%, average hydraulic residence time t__M=75 h. The average COD value of the treated water flown out of the ponds, COD_e, obtained from 16 monitoring measurements in July, 2001 is of 127.6 mg/L (average water temperature T_M=35.8℃ and average COD value of the inlet water?—?169.4 mg/L) while the COD_e value calculated by using model Ⅰ is of 126.2 mg/L with a relative error ε=-1.10% and by using model Ⅱ?—?126.5 mg/L with ε=-0.86%. Comparing with the real average monthly values of COD_e measured in Dec, 2000 to July, 2001 (with T__M varying in 10.9—36.0℃), the COD_e values are calculated with ε values ranged in -4.5—+4.5% and in -4.42—+4.18% and of +0.453% amd +0.581% in average by using model Ⅰ and model Ⅱ, respectively. The 2 models can be applied to predicting the results of wastewater treatments in oxidation ponds and to designing such ponds.