Baihetan Hydropower Station air cooler inlet and outlet DN400 butterfly valve

1. On-site application conditions introduction

1.1 Valve installation location: The inlet and outlet pipelines of the air cooler of unit 10 on the right bank of the Baihetan Hydropower Station, with a diameter of DN400, nominal pressure: PN16, vertical pipe installation.

1.2 Medium process parameters: Diameter DN400, nominal pressure: PN16, working pressure: 0.3~0.6MPa, working temperature: normal temperature, medium: Jinsha River water.

1.3 Valve operating conditions

(1) The valves are all in normal temperature conditions, but the frequency of operation is not high, and positive and reverse operation (double-direction sealing) is required;

(2) Most of the valves in the modified location are partially open or half-open.

1. Problems and challenges faced

The diameter of the pipeline valve is designed to be too large, and the actual demand flow rate is too small, so the actual opening of the DN400 butterfly valve is 25%~50%, so vibration and loud harsh noise are generated during operation.

2. EICMATION's recommended solution

Analysis is as follows:

Pipeline noise refers to the sound generated during the movement of liquid or gas. In industrial production, pipeline noise is a common noise source, which can affect the production environment and the health of workers, and will also negatively affect the normal operation of equipment. In order to effectively control pipeline noise, we need to understand the generation principle of pipeline noise.

The generation principle of pipeline noise mainly involves two aspects: one is the oscillation and disturbance inside the fluid, and the other is the friction between the fluid and the pipe wall.

In terms of oscillation and disturbance inside the fluid: When the fluid flows in the pipeline, due to the viscosity and inertia of the fluid, various vortices and turbulence will be formed in the fluid. During the fluid flow process, the interaction between the fluid and the solid structure causes the fluid to generate vortices, impacts, or pressure changes, leading to fluid disturbances and noise. It is mainly composed of rotational noise (fluid pressure pulsation) and vortex noise (turbulence noise). The opening of the butterfly valve at the inlet and outlet of the air cooler on site is relatively small, and the impact of the fluid on the butterfly plate will also intensify the generation of vortices and turbulence, thus further increasing the generation of noise. The specific location of the noise and the fixed structure in the flow field is the manual butterfly valve (DN400, PN16, CF8) at the water pipe of the air cooler, with an opening of only 25 degrees.

In terms of friction between the fluid and the pipe wall: When the fluid passes through the pipe, it will generate friction with the pipe wall. This friction will cause the fluid to lose energy, thereby generating heat and noise. When the speed of the fluid is higher, the noise generated by the friction of the pipe wall will be more obvious. Only when the Mach number of the fluid medium is greater than 1 (i.e., the speed of sound is about 344 meters/second) will obvious noise be generated. For the air cooler water pipe of the Baihetan Hydropower Station, its water supply flow rate is far less than the speed of sound, so the noise generated by friction can be ignored.

Therefore, the air cooler water pipe of the Baihetan Hydropower Station only involves the fixed structures in the flow field, such as the small opening of the butterfly valve, which generates vibration and loud harsh noise.

Solution: Turbine manual single-piece V-type ball valve, model: BTN33M3628-DZL27800, valve body/internal parts: CF8/304+STL, sealing: STL, pressure: PN16, connection method: national standard flange, diameter: DN400.

(1) Product overview

Ekmexun BTN series V-type ball valves have a V-shaped opening on one side of the hemispherical valve core. By adjusting the opening of the valve core, the cross-sectional area of the medium flow is changed, which is used to regulate the flow rate of the valve. It can also be used for on-off control to achieve the opening or closing of the pipeline. It has a self-cleaning function, can achieve micro-flow regulation within a small opening range, has a large adjustable ratio, and is suitable for media containing fibers, fine particles, and slurries.

(2) Structural characteristics and working principle

The BTN series V-type ball valve is a type of fixed ball valve. Its closing member is a hemisphere with a V-shaped opening. The V-shaped opening has a sharp edge. During the rotation of the ball, there is a wiping action between the closing members, which has a strong cutting force on the medium. The V-shaped opening of the ball and the flow channel of the valve seat form a fan-shaped area. During the rotation process, the flow channel cross-sectional area can be changed to form precise regulation of the medium. It is a quarter-turn regulating valve, and its regulating performance is the best among ball valves. The flow characteristic is approximately equal percentage, and the adjustable ratio is up to 100:1. Its sealing performance is the same as that of ordinary ball valves. It adopts a movable valve seat structure with disc spring or spring loading. Due to the elastic restoring force pushing the valve seat, the ball core and valve seat can be optimally matched, with good unidirectional or bidirectional sealing performance. The connection with the actuator adopts the standard ISO5211 platform, and it is matched with pneumatic or electric actuators, widely used in industrial process control systems.

(3) Basic parameters

Product model: BTN

Diameter range: DN25—DN500;

Control method: Manual, pneumatic, electric, etc.

Applicable medium: Water, gas, oil, ore pulp, etc.

Temperature range: -30℃--350℃

Valve body material: Carbon steel, stainless steel, alloy steel, etc.

Connection method: Double-flanged, flanged

The structural diagram of the BTN series fixed V-type ball valve is as follows: (double-direction sealing)