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TK series orifice plate control valve

key word:Heat exchange element


Product description

TK series orifice plate control valve

 

1. Introduction

1.1. Purpose

Orifice plate control valve is mainly used in the occasions where the regulation characteristics require high temperature, high pressure difference and flow need to be regulated. It is widely used in power plant boiler class I and II spray desuperheating water, minimum flow valve of feed pump, main feed water regulation, bypass feed water regulation and other flow regulation.

1.2. Model meaning

T**##&&-$$@@/※※

T - control valve code

**----M is labyrinth type; K is orifice plate type; Y is cone type; L is shrouded type

##-------D is electric; Q is pneumatic; Y is hydraulic

&&---------1 represents balanced spool; 2 represents unbalanced spool; 3 represents pressurized spool

$$--- nominal pressure (MPa)

@@--------------Valve body material (see table 33-1 for specific code)

※※----------Nominal diameter (mm)

Table 33-1

Valve body material Code
Grey cast iron Z
Mallable iron K
nodular cast iron Q
Copper and copper alloys T
Carbon steel
Cr Ni Ti steel P
Cr Mo alloy steel I
Cr Mo V alloy steel V

 

1.3. Structural features

1.3.1. Structure description. The anti cavitation design of orifice plate series regulating valve is based on the principle of multi-stage pressure reduction of orifice plate core package. By forcing the medium to flow through many small holes on the orifice plate of core package, the flow rate can be completely controlled, so as to achieve the purpose of step-by-step pressure reduction. Regardless of the pressure drop, the resistance of these holes limits the velocity of the medium flowing out of the core. After multi-stage depressurization, the pressure of the medium is always maintained above the vaporization pressure of the medium, so as to avoid cavitation phenomenon and eliminate unsafe factors.

1.3.2. Description of important parts:

Each hole can pass through a number of channels (see figure 33-1). When the medium flows through the small hole, there is a great resistance, and then there is a pressure drop. According to the different parameters of various units in the power plant, through accurate calculation, the number of different orifice plates, the number of different small holes on the orifice plates and the diameter of the small holes are selected, so that the medium pressure drop through the orifice plate core can meet the needs of different occasions in the power plant, and the pressure drop of each stage can always be kept above the vaporization pressure, so as to meet the requirements of anti cavitation.

Figure 33-1 orifice plate series valve core package

1.3.2.2. The balanced valve core can reduce the requirement on the executive force of the actuator, and a symmetrical hole is drilled on the valve core. The upper part of the valve core is equipped with a balance seal ring with an upward opening, which is used to isolate the pressure between the outlet and the inlet. The symmetrical hole on the valve core balances the pressure of the valve core up and down, which greatly reduces the lifting force requirements, thus reducing the torque of the actuator, reducing the volume and mass of the actuator.

In medium and low temperature conditions, the balance seal ring is made of filled polytetrafluoroethylene; in high temperature conditions, graphite material is often used.

1.3.3. Important characteristics:

1.3.3.1. Varistor characteristics. Under the condition of small opening, the medium of orifice series valve needs to flow through the whole core package, so it can meet the requirements of high pressure drop and small flow without cavitation. With the increase of the valve opening, the number of medium flowing through the orifice plate is gradually reduced, and the resistance is also gradually reduced. If the valve opening exceeds the height of the core package, the medium will completely flow through the deflector, and the resistance can be very small, so it can meet the requirements of large flow, so as to reduce the energy consumption of the feed pump.

1.3.3.2. Low noise characteristics. The orifice plate control valve is composed of a plurality of orifice plates arranged and stacked in a staggered way according to certain design rules. The medium flows upward from the lower part of the orifice plate. Because of the segmented pressure reduction of the orifice plates, cavitation is prevented. In addition, the orifice plate itself is an excellent muffler, so the orifice plate control valve has the characteristics of low noise.

 

2. Main technical parameters and product shape

2.1. Main technical parameters (see table 33-2)

Table 33-2 main technical parameters of TK series orifice plate control valve

Item Parameter
Nominal pressureMPa 0754500 Poung grade
Nominal diameter (mm) 20500
Applicable units 501000MW units
Rated flow (t/h) 03600
Working temperature(℃) 620
Working medium Water, steam, corrosive medium
characteristic curve Linear, equal percentage, corrected equal percentage or other
Connection form of inlet and outlet Flange connection or butt welding connection
Supporting actuator Electric, pneumatic or other

2.2. Product appearance (see figure 33-2)

 

3. Selection method

Generally, the selection of valves can refer to the recommended valve structure and type to determine the main technical conditions of the valve. According to the regulation requirements and the working temperature, pressure, density, noise and other conditions of the medium, not only the flow characteristics and flow coefficient should be considered For the inherent static characteristics of valves such as Cv or KV, allowable pressure difference and regulation range R, the influence of the dynamic characteristics such as the distortion of flow characteristics caused by the changes of system resistance and operating conditions due to the different parallel and series positions of the valves installed on the actual pipeline must also be considered.

 

4. Scope of supply and general technical specifications

4.1. Scope of supply

It includes the valve body and the actuator matched with the valve, and other accessories, such as interface pipe, reducing joint, etc., are selected according to the user's requirements.

4.2. General technical specifications

Valve product design reference standard:

ASTM A182 / A182M-2008     Forged or rolled alloy steel nominal pipe flanges, forged pipe fittings, valves and parts for high temperature service

ASME B16.34-2004    Flanged, threaded and welded valves

ASME B16.10-2000     Valve structure length

ASTM A370-2003a       Definite and test method for mechanical properties of steel products

ASTM A-388 / A 388M-2004       Standard Practice for ultrasonic inspection of heavy steel forgings

GB / T12224-2005       General requirements for steel valves

GB / T 10868-2005       Desuperheating and pressure reducing valve for power station

GB / T 13927-1992        General purpose valve pressure test

GB / T 5097-2005         Non destructive testing, penetrant testing and magnetic particle testing observation conditions

GB / T 19672-2005         Specification for pipeline valves