welded plate heat exchanger,compabloc,compabloc exchanger,welded heat exchanger,block heat exchanger,welded plate block heat exchanger,block type heat exchanger Siping Juyuan Hanyang Plate Heat Exchanger Co., Ltd , https://www.tj-heatexchange.com
Development of Design and Calculation of Urban Drainage Pipe System
**Abstract:** In the context of municipal construction and environmental management projects, rainwater and sewer systems often represent a significant portion of the investment. Therefore, how to design urban drainage piping systems rationally under various technical conditions that meet regulatory requirements is a critical issue in the design process. This paper discusses the methods and challenges involved in the design and calculation of sewer systems from three perspectives: optimized design under fixed pipelines, planar layout of pipelines, and stormwater runoff modeling. It is evident that further research and improvement of design and calculation methods are essential for future developments.
**Keywords:** drainage system; optimization design; layout; runoff model
**Introduction:**
The drainage system is an indispensable and crucial infrastructure in modern cities, serving as the backbone of urban water pollution control, flood prevention, and drainage management. In residential areas and industrial zones, the investment in rainwater and sewer systems typically accounts for approximately 70% of the total drainage system cost [1]. Thus, minimizing the capital cost of the pipeline system while meeting all technical specifications is a key concern in the design process. Traditional design methods involve determining a reasonable sewage pipeline layout based on alignment principles, followed by calculating the design flow for each section using hydraulic calculation diagrams or tables. The pipe diameter, slope, and elevation at inspection wells are then determined through experience-based adjustments. However, this approach is limited by the designer's personal capacity and relies heavily on manual table lookups, leading to inefficiency and suboptimal results.
Since the 1960s, the international community has gradually developed mathematical models for water supply and drainage systems, enabling a more quantitative and semi-quantitative "rational design and management" phase. Optimized research and practical applications have been conducted on various types of water supply and drainage systems [2]. To explore optimal design and calculation methods for sewer systems, numerous domestic and foreign scientific institutions, designers, and researchers have contributed significantly, publishing a large number of articles. Computer-aided design not only reduces the labor of consulting charts but also optimizes the entire drainage system and improves design quality. Compared to traditional methods, optimal solutions can reduce construction costs by over 10% [3].
The drainage pipeline system is a complex and large-scale system. According to existing research, the design and calculation of drainage pipelines mainly involve three aspects: (1) optimization of pipe diameter and burial depth; (2) optimization of pipeline layout; and (3) establishment of stormwater runoff models. Condensate drainage systems often include overflow facilities to limit the amount of water delivered to local wastewater treatment plants. Since overflowed rainwater is also discharged into nearby rivers, the impact of combined flow drainage systems on the drainage area is similar to that of separate-flow rainwater systems [4].
**Optimized Design of Piping System under a Given Pipeline**
Extensive groundbreaking work has been done both domestically and internationally on the optimization of pipe diameter-depth under established pipeline layouts. Optimization methods are generally divided into two categories: indirect and direct optimization. Indirect optimization, also known as analytical optimization, relies on mathematical models to find the optimal solution through optimization calculations. Direct optimization, on the other hand, involves adjusting performance indicators and tunable parameters to achieve the best or satisfactory solution [5].
**1.1 Direct Optimization Method**
In the optimization design of drainage pipes, the direct optimization method is considered [6–8]. Although the hydraulic calculation formula for drainage pipes is simple, the selection of pipe diameters is not continuous, and the maximum fullness limit is related to the pipe diameter. Additionally, the minimum design flow rate and its constraints on the pipe diameter make it difficult to establish a complete mathematical model using indirect optimization methods. In contrast, the direct optimization method offers advantages such as simplicity, intuitiveness, and ease of verification.
**1.2 Indirect Optimization Method**
Indirect optimization methods, including linear programming, nonlinear programming, dynamic programming, and genetic algorithms, have been widely used in drainage system design. Linear programming, for example, is one of the most commonly used algorithms for solving many problems in sewer design. However, it treats pipe diameter as a continuous variable, which may conflict with commercially available sizes [9]. Nonlinear programming, introduced in 1972 by Dajani and Gemmell, handles non-linear objective functions and constraints but may result in local optima rather than global ones if the cost function is not unimodal [10]. Dynamic programming, first applied by Mays and Yen in 1975, is effective for multi-stage decision-making problems but requires careful state interval selection to avoid excessive computational time [11]. Genetic algorithms, a rapidly developing technique, offer flexibility in handling complex optimization problems without strict requirements on objective functions or constraints [17].
**2 Planes for Planar Optimization of Pipelines**
Researchers have identified that optimizing drainage systems under given pipelines is more suitable for different alignment schemes. However, due to the immaturity of planned pipeline design and optimization, progress in system layout optimization has been limited. Early studies by JCLiebman (1976) focused on hydraulic factors, assuming uniform pipe diameters and using excavation costs as a basis for initial arrangements [19]. Subsequent work by Argaman and Mays introduced the concept of drainage lines, transforming the layout problem into a shortest path problem solvable via dynamic programming. While this approach considers hydraulic factors, it limits the search space to a small feasible area, potentially excluding optimal solutions [19].
**3 Study on Rainfall Runoff Model**
China’s stormwater canal design has traditionally relied on inference formula methods, which assume uniform flow in channels and equate rainfall duration to surface catchment time. However, these methods have limitations, such as not accounting for spatial rainfall variation, making simplistic assumptions about parameters, and failing to simulate complete runoff processes [22]. Recent advancements in urban runoff modeling, particularly in the West, include programs like the Wallingford Procedure, STORM, and SWMM, which provide accurate simulations of both quantity and quality of rainfall and runoff [23]. In China, efforts have been made to develop models tailored to local conditions, such as simplified diffusion wave and kinematic wave models for rainwater networks [25].
**4 Conclusion**
Both domestic and international efforts have yielded significant achievements in the theoretical and practical application of drainage system design. However, many challenges remain. With the development of computing technology and system methodologies, the creation of advanced design and calculation software for drainage systems is an inevitable trend.
**References**
1 Gu Guowei. Research on Water Pollution Control Technology. Shanghai: Tongji University Press, 1997
2 Fu Guowei. Introduction to Water Supply and Drainage System Optimization (1). China Water and Wastewater, 1987, 3 (4): 45–50
3 James, S J. Optimal design of sanitary sewers. Computing in civil engineering proceeding of the fourth conference, Edited by W Tracy Lenocker, Published by the American Society of Civil Engineers 1986: 162 ~ 177
4 MJ Hall [English], translated by Zhan Daojiang etc. Urban Hydrology. Nanjing: Hohai University Press, 1989
5 Peng Yongzhen, Cui Foyi. Computer programming of water supply and drainage engineering. Beijing: China Building Industry Publishing House, 1994
6 Wang Boren. Calculation of sewer system and optimization options. China Water & Wastewater, 1985,1 (2): 1 ~ 5
7 Peng Yongzhen, Wang Shuying, Wang Fuzhen. Global Optimization of Drainage Network Calculation Program. , 1994,10 (5): 41 ~ 43
8 Zhang Lianmin. Flow rate control method for optimal design of sewer network. China Water & Wastewater, 199 4,10 (5): 41 ~ 43
9 Shen Yi.Application of Microcomputer in Sewage Pipeline Optimal Design. Ministry of Communications First Flight Engineering Prospecting and Design Institute, 1988
10 Li GY and Matthew, GS R. New approach for optimization of urban drainage systems. Journal of environmental engineering, ASCE, 1990, 116 (5): 927-944
11 Kuo JT and Yen B C. Hwang, GP P. Optimal design for storm sewer system with pumping stations. Journal of water resource planning and management, Journal of Xi'an Institute of Metallurgy and Architecture, 1993,25 (3): 305 ~ 310
13 Li Guiyi.Drainage network optimization design.China water supply and drainage (2): 18 ~ 23
14 Ouyang Jianxin, Chen Xinshang. Discrete Optimization of Penalty Function for Drainage System Design. Water Supply and Drainage, 1996,22 (5): 19-21
21 Ding Hongda. Dynamic Planning of Gravity Flow and Rainfall Water Pipe System Analysis. Water Supply and Drainage, 1983,9 (5): 2 ~ 7
16 Lu Shaoming, Liu Suiqing. Optimized Design of Feasible Pipe Diameter for Urban Sewer Network. Journal of Tongji University, 1996,24 (3): 275-280
17 Simpson AR, Dandy GC and Murphy L J. Genetic algorithms compared to other techniques for pipe optimization. Journal of water resource planning and management, 1994,120 (4): 423 ~ 443
18 Zhang Jinguo, Li Shuping. Genetic algorithm for drainage system optimization design. China Water and Wastewater, 1997 , 13 (3): 28 ~ 30
19 Li Guiyi. Optimization design of drainage channel system. Information Technology Station of Tongji University, 1986
20 Chen Senfa. Hierarchical Optimization Design of Urban Sewer Network System Layout. China Water Supply and Drainage, 1988,4 ( 3): 6 ~ 10
21 Walters GA and Lohbeck T K. Optimal layout of tree network using genetic algorithms. Engineering Optimization, 1993, 22: 27 ~ 48
22 Hydrology Bureau of Ministry of Water Conservancy and Electric Power.
23 Wang Wenyuan, Wang Chao. Enlightenment from the Development of Foreign Urban Drainage Systems. China Water and Wastewater, 1998,14 (2): 45 ~ 47
24 Harry van Mameren and Francois Clemens. Guidelines for hydrodynamic calculations on urban drainage in the and principles. Water science and technologies, 1997,36 (8): 247 ~ 252
25 Cen Guoping. DYNAMIC WAVE SIMULATION AND EXPERIMENT OF RAINWAY NETWORK Journal of Water Supply and Drainage, 1995,21 (10): 11 ~ 13
26 Zhou Yuwen, Meng Shaolu. Study on the process of in-line flow of rainwater network by instantaneous unit line method.
Block heat exchangers are compact, modular heat exchange devices classified based on materials, structural designs,
application scenarios, and manufacturing processes. the structured summary of classification as below: Classification by Material
Â
1. Graphite Block Heat Exchanger - Structural Features: Made of impregnated or molded impervious graphite, offering high corrosion resistance and
thermal conductivity. Common types include cylindrical block-type (e.g., Cylindrical Block Graphite Heat Exchanger)
and shell-and-tube graphite heat exchangers. - Applications: Ideal for corrosive media like strong acids or alkalis, such as heat exchange in phosphoric acid production. 2. Ceramic Block Heat Exchanger - Structural Features: Fabricated from monolithic ceramic blocks with elongated cross-sectional channels. The overlapping
arc-shaped channel walls enhance fluid flow efficiency. - Applications: Suitable for high-temperature or high-wear environments in chemical and energy industries. Classification by Structural Design
Â
1. Block-and-Hole Heat Exchanger - Composed of multiple perforated graphite blocks stacked together, allowing fluid exchange through interconnected channels (e.g., *Cylindrical Block Graphite Heat Exchanger*). 2. Shell-and-Tube Block Structure - Modular shell-and-tube designs, including fixed-tube and floating-head types. Examples include *Complex Shell-and-Tube Graphite Heat Exchanger*. 3. Monolithic Block Heat Exchanger - Single-piece structures formed by casting or injection molding, eliminating welds and enhancing pressure resistance (e.g., ceramic or metal monolithic blocks). Classification by Special Functions
Â
1. High-Pressure Thread-Locked Ring Heat Exchanger - Design Features: Employs threaded locking rings for sealing, suitable for high-pressure hydrogen environments (e.g., hydrogenation reaction systems). Corrosion resistance is improved via optimized materials like hydrogen-resistant steel. 2. Corrosion-Resistant Block Heat Exchanger - Examples include *Double-Side Corrosion-Resistant Cylindrical Block Graphite Heater*, designed for strong acid media. Classification by Manufacturing Process
Â
1. Modular Assembly Type - Multiple modules connected via bolts or adhesives, facilitating maintenance (common in graphite heat exchangers). 2. Integrated Monolithic Type - Molded in one piece for high structural integrity, such as cast ceramic or metal blocks. Application Scenarios
Â
- Chemical Industry: Graphite and ceramic block exchangers handle corrosive media (e.g., sulfuric acid, phosphoric acid). - Energy & High-Pressure Systems: Thread-locked ring exchangers are used in petroleum hydrogenation and high-pressure steam systems. - High-Temperature Environments: Ceramic blocks excel in waste heat recovery from high-temperature exhaust gases.