第3期 王 群 填料塔支承梁的设计计算・21・
填料塔支承梁的设计计算
群
王群:1989年毕业于武汉化工学院化工设备与机械专业, 工程师, 从事化工设备设计工作。
, 建立了不同的力学模型, 推导并提设计人员可直接利用公式对支承梁进行设计计算。
关键词 填料塔 支承梁 设计计算
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1 引 言
在填料塔的结构设计中, 需考虑填料支承装置下的支承梁设计。散堆填料, 目前较多采用波纹多孔板支承结构, 俗称“驼峰板”, 一般用不锈钢制造, 厚度2～3mm 。驼峰板不但要承受填料及其所含液体的重量, 而且要分布气体, 因此不仅要有足够的强度和刚度, 而且要有较大的开孔率。支承梁应能保证有足够的强度和刚度, 支承梁设计按下列选取。
塔径D N (mm )
D N ≤2500
M 2=P ×D/6=qD /
96
3
推荐支承梁数
012
图1 单梁载荷分布示意图
2500
D N >4000
图1(d ) w 2=q ・D/2
R 3=w 2D/4=qD 2/8
M 3=R 3・D/2-w 2・D/4・D/8
2 力学模型及公式
在计算支承横梁载荷时, 考虑塔内支持圈的部分支承作用。同时, 将支承梁看成是承受均布载荷的简支梁, 略去填料对塔壁的摩擦阻力。2. 1 单梁计算方法
(c ) 、(d ) 载荷分布如图1(a ) , 可分解为(b ) 、
=3qD 3/64
则R =R 1+R 2+R 3
=w 1×D/2+qD 2/16+qD 2/8=w 1D/2+3qD 2/16
M =M 1+M 2+M 3
………(2-1)
三种受力状况进行叠加。
由材料力学理论可方便地求出以下公式:图1(b ) R 1=w 1×D/2
M 1=w 1D /8
2
=w 1D 2/8+qD 3/96+3qD 3/64=w 1D 2/8+11qD 3/192
2. 2 双梁计算方法
………(2-2)
图1(c ) P =q ×1/2×(D/4) 2×2
=q ×(D/4) 2
R 2=P =q ×(D/4) 2=qD 2/16
载荷分布如图2(g ) , 可分解成(h ) 、(i ) 、(j ) 3种受力状况进行叠加。
同理, 由材料力学理论可以求出以下公式:图2(h ) R 1=w 1×L /2
・22・
M 1=w 1L /8
2
化肥设计 2000年第38卷
(4) 求梁的最大弯曲应力σ=M /W ;
(5) 满足σ≤[σ], 校核合格。
图2(i ) P =q ×1/2×(D/6+2D/6) ×L /4
=qDL /16
R 2=P =qDL /16
M 2=P ×5L /36=5qDL /576
2
4 符号说明
F ———一层填料段上的总载荷,N ; 包括湿填
图2(j ) w 2=q ×D/3
R 3=w 2L /4=qDL /12
M 3=R 3×L /2-w 2×L /4×L /8
=qDL 2/32
则R =R 1+R 2+R 3
=w 1/+/=w 1L /2/48…………(2-3)
M =M 1+M 2+M 3
料、填料支承板、液体再分布器及其内
D 2H γ×F (10-9/4+Q ) ×9. 81
G ———一根横梁上承受的载荷,N ; 包括湿填料重量及其它需要计及的重量。
G =(HS γ×10-9+Q ) ×9. 81H ———填料高度, mm ; S ———承载面积, mm 2; γ———填料和液体的组合堆积重度,kgf/m 3; 无确切数据时, 不锈钢填料可取填料
堆积重度的1. 4倍; 塑料填料可取塑料填料堆积重度与30%不锈钢填料堆积重度之和作为组合堆积重度。Q ———其他部件(如填料支承板、填料压板
等) 作用在梁上的载荷, kgf ;
q ———均布载荷,N/mm ;
q =F /πD /4=4F /πD D ———塔体内径, mm ; L ———支承横梁长度, mm ;
2
2
2
=w 1L 2/8+5qDL 2/576+qDL 2/32=w 1L 2/8+23qDL 2/576……(2-4)
σ———设计温度下梁的最大弯曲应力, MPa ; [σ]———设计温度下梁的许用弯曲应力,
MPa ;
图2 双梁载荷分布示意图
M ———梁上的总弯矩, N -mm ;
M =M 1+M 2+M 3
W ———梁的抗弯截面模数, mm 3;
R ———总支点反力, N ; R =R 1+R 2+R 3P ———集中力, N ; T ———梁的自重, kgf ;
w 1———梁单位长度自重载荷, N/mm ;
w 1=T/L 9. 81
w 2———梁中部单位长度均布载荷, N/mm ; C ———腐蚀裕量, mm ;
(收稿日期 2000-02-29)
3 设计步骤
(1) 根据塔径、受到的载荷及其工作要求,
选择适当的材料, 确定型钢梁的数量、截面形状
和尺寸;
(2) 根据公式(2-1) 、(2-2) 和(2-3) 、(2-4) , 按不同情况求梁的最大弯矩M ;
(3) 计算型钢梁的抗弯截面模数W (计算时
应考虑双面腐蚀, 即截面的计算厚度δ=δn -2C ) ;
CHEMICAL FERTIL IZER DESIGN
・3・
Vol. 38 No. 3 June 2000(total No. 195)
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