EVALUATION OF THE TECHNICAL AND ECONOMIC EFFICIENCY OF CENTRIFUGAL PUMPS AT IRRIGATION PUMPING STATIONS

АННОТАЦИЯ

В статье исследуется повышение эффективности центробежных насосов Д6300-27 в оросительных системах путем оптимизации углов лопаток. Сравниваются конфигурации лопаток с углами 28 и 30 градусов, показано, что угол в 30 градусов снижает потребление электроэнергии и увеличивает экономию. Исследование подчеркивает экономическую выгоду этой модификации с расчетами годовой экономии энергии для нескольких насосных станций.

ABSTRACT

The article examines the efficiency improvement of D6300-27 centrifugal pumps in irrigation systems by optimizing blade angles. The study compares 28 and 30-degree blade configurations, showing that the 30-degree angle reduces power consumption and enhances energy savings. The research highlights the economic benefits of this modification, with calculations of annual energy savings for multiple pumping stations.

Ключевые слова: Насосная станция, источник воды, канал подачи воды, лопастная камера, рабочее колесо насоса, всасывающий и напорный трубопроводы.

Keywords: Pumping station, water source, water supply canal, blade chamber, pump impeller, suction and discharge pipelines.

Introduction

In the design of irrigation pumping stations, various blade options for centrifugal pumps with technically equal performance can be determined, fully ensuring the operating mode for water pumping and pressure. The degree of acceptability and cost-effectiveness of the planned structures is based on technical and economic calculations. In the practice of water construction, the method of comparing economic efficiency is used to determine whether the technical solution of one option is more effective than another [1].

Main Part

The calculation of the economic efficiency of centrifugal pumps D6300-27 was carried out by introducing a modernized impeller into the centrifugal pump. The study established the current parameters of the D6300-27 pump: water flow rate Q = 6033 m³/h, pressure H = 14 m. The electric motor used for power generation is of the SD13-42-10 type, with a power output of N = 400 kW and a rotational speed of n = 1000 rpm.

Based on the research and design developments aimed at reducing cavitation erosion in centrifugal pumps, various "impact angles" of the impellers and blades were calculated and improved. Specifically, designs with angles of 28 and 30 degrees were explored. The most suitable impeller design is one with backward-curved blades, meaning the blades are turned against the direction of the flow. This type of impeller blade significantly increases the pump's efficiency, accelerates the conversion of kinetic energy into potential energy in the flow part, and reduces cavitation phenomena [2].

The cost of electrical energy used for water transmission in irrigation pumping stations, along with staff salaries, repair costs, depreciation deductions, labor protection, and lubrication material expenses, is referred to as the annual operational costs (E) [3].

To determine the annual cost of electricity in centrifugal pumps at irrigation pumping stations, the actual pressure Hi, water flow rate Qi, and efficiency ηi of the pumps during each water transmission period are taken from the pump characteristics. The power of the pumping station for each period ti is calculated using the following formula (in kW):

;

Here is the translation:

Here,  represents the efficiency of the electric motors during different water transmission periods;  is the total water transmission of the operating pump units during each period t_i , measured in m³/s. 

The total amount of electrical energy consumed during the year (kWh) is calculated as follows:

Е = (N₁ t₁ +N₂ t₂ + …+ N_n t_n) 24 ;

Here is the translation:

Here, N₁,  N₂ …N_n  are the powers of the pumping station during different water transmission periods (kW); t₁, t₂ … t_n are the water transmission periods of the pumping station, measured in days: 

The annual cost of consumed electrical energy (in soums) is calculated as follows: 

С_эн = ( ) S;

Here, S is the price of electrical energy in kWh, in soums; 0.02⋅E is the amount of electrical energy consumed by the station for its own needs, in kWh.

As a result of the research, while maintaining the nominal characteristics of the D6300-27 pump, improvements to the pump's impeller were made. Testing revealed that when the impeller blades are at an angle of 30 degrees, the pump consumes 396 kW of power, resulting in a difference of 4 kW. The average annual operation of this pump, taking into account maintenance and other types of work, is 3381.8 hours with a utilization factor of k=0.77.

183 days/year х 24 hours т х 0,77 = 3381,8 motor hours/year.

The calculation of costs includes 1 kWh = 1000,0 sum (as of July 1, 2024).

Additionally:

400 kW х 3381,8 motor hours/year х 1000,0 sum = 1 055 121 600 sum/year.

396 kW х 3381,8 motor hours/year х 1000,0 сум = 1 041 594 400 sum/year.

The annual cost savings on energy is 13,527,200 soums/year.

Table 1.

Comparative Table of Annual Energy Savings

As a result of implementing this pump design, the economic efficiency is calculated to reduce electricity consumption by 0.05% per year.

Figure 1. Annual Electricity Savings Graph

In the Andijan region, there are 16 existing D6300-27 pumps, and if the impeller blades of these pumps are operated at an angle of 30 degrees, the following calculation applies:

4 kW×16×3381.8 hours/year×1000.0 soums=216,435,200 soums/year

The expected annual economic benefit from electricity costs is approximately 216,435,200 soums.

CONCLUSION

Evaluating the technical and economic efficiency of centrifugal pumps allows for the following conclusions:

In assessing the technical and economic efficiency of irrigation pumping stations, it is essential to monitor the electrical energy consumed by the pump, implement measures to save electricity, and improve the main performance indicators of the pump.

References:

1. Mamazhonov M. Increasing the efficiency of operation of centrifugal and axial pumps at irrigation system pumping stations/ dissertation. Andijan, 2005. [in Russian]
2. Mamazhonov M., Hakimov A., Majidov T., Uralov B. Practical exercises on pumps and pumping stations. // Andijan, 2005. No. 1. Pp. 72-73. [in Uzbek]
3. Rashidov J.I. Improving the water flow characteristics of centrifugal pumps in irrigation systems. Tashkent, 2023. [in Uzbek]
4. Gildebrandt M.I. Increasing the efficiency of existing pumping equipment at pumping stations / dissertation. Omsk, 2022. [in Russian]
5. Shakirov B.M., Ermatov K.M., Abduhalilov O.A., Shakirov B.B. Experimental setup for studying centrifugal pumps on cavitation and hydroabrasive wear. // International Scientific Journal. 2022. No. 5. Pp. 692-697. [in Russian]
6. Shakirov B.M., Abduhalilov O.A. Determining the optimal angle of inclination of centrifugal pumps at irrigation pumping stations. // Proceedings of the International Scientific and Technical Conference on "Current Issues of Fundamental and Applied Research: Achievements and Innovative Solutions." Bukhara, 2024. No. 1. Pp. 201-204. [in Uzbek]