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TM series labyrinth control valve

key word:Heat exchange element


Product description

TM series labyrinth control valve

 

1. Introduction

1.1. Purpose

TM series labyrinth control valve is mainly used in the occasions of high regulation characteristics, high temperature, high pressure difference and flow adjustment. It is widely used in the power plant boiler class I and II spray desuperheating water, minimum flow valve of feed pump, continuous discharge water regulation, main feed water regulation, shaft seal water regulation, main steam regulation, soot blowing steam regulation, air exhaust, high and low bypass, temperature and pressure reducing device 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 32-1 for specific code)

※※----------Nominal diameter (mm)

Table 32-1 material code of valve body

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

Example: TM D3-25C / 50 represents labyrinth control valve, electric actuator, pressurized spool structure, valve pressure is 25MPa, valve body material is carbon steel, nominal diameter of valve body is 50mm

1.3. Structural features

1.3.1. Structure description. The anti cavitation design of labyrinth series regulating valves is based on the principle of multi-stage pressure reduction of labyrinth core package. By forcing the medium to flow through a series of right angle bends, 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 velocity of the medium flowing out of the core is limited by the wind force in these bends. Through multi-stage depressurization, the pressure of medium is always maintained above the vaporization pressure of medium, so as to avoid cavitation phenomenon and eliminate unsafe factors

1.3.2. Description of important parts

1.3.2.1. The core package of miguan series regulating valve (see figure 32-1) includes many miguan pieces. Many channels are formed by electric corrosion processing, and each channel can pass through quantitative medium. A series of right angle bends provide the medium resistance in the channel. According to the different parameters of the power plant, different bends are selected after accurate calculation, so that the medium velocity through the labyrinth core package is always less than 30m / s. Referring to the mature experience abroad, when the flow rate is less than 30 m / s, the erosion effect on the throttle element is the smallest.

1.3.2.2. The balanced valve core reduces the requirement of actuator driving torque. A symmetrical hole is drilled on the balanced valve core, and a balance seal ring is installed on the upper part of the valve core to isolate the space of the valve cover and the upstream pressure. Therefore, 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 pressure seal is made of filled polytetrafluoroethylene; in high temperature conditions, the pressure seal is made of graphite.

1.3.2.3. Pressurized valve core. In the high temperature condition, when the close requirement is very high, the labyrinth control valve will use pressurized spool. The pressurized spool can provide the sealing performance of the non balanced spool, while the thrust requirement of the actuator is only equivalent to that of the balanced spool.

The labyrinth pressurized spool assembly consists of a pilot valve, a main spool and a balance seal. When working, the small and controlled flow flows from the valve inlet through the valve cap into the bonnet space to pressurize the pilot valve and the main spool.

When the valve is closed, the pilot valve is closed, so that the entire spool becomes an unbalanced spool. The pressurized valve core can meet the high closing requirements. The closing pressure on the valve core in the bonnet space is applied on the valve core to close the valve. As long as the actuator has the force to close the pilot valve on the main valve. When the valve receives the opening signal, the actuator lifts the pilot valve stem to open the pilot valve. The pilot valve makes the pressure in the valve cover space disappear quickly, and the valve core is balanced. Continue to open the valve stem and pull up the main valve core. The actuator only needs to have the force to lift the balanced spool.

1.3.3. Important characteristics:

1.3.3.1. Low noise, anti cavitation, can withstand high pressure difference

1.3.3.2. Depressurize the multi-layer labyrinth disk, limit the medium flow rate, and keep the medium pressure above the vaporization pressure.

1.3.3.3. The labyrinth piece can be designed to be thin, with good regulation performance and precise flow control.

1.3.3.4. The valve core and valve seat adopt different angles to achieve line contact seal, with good closing performance

1.3.3.5. The pressurized valve core adopts the pilot valve structure, which can close more tightly and has small regulating torque.

1.3.3.6. The labyrinth disc adopts cofferdam structure to make the pressure around the valve core uniform.

1.3.3.7. The sealing surface is overlaid with Stellite cemented carbide to ensure that the sealing surface can work for a long time.

 

2. Main technical parameters and product appearance

2.1. Main technical parameters (see table 32-2)

Table 32-2 main technical parameters of TM series labyrinth control valve

Item Parameter
Type of control valve TM series labyrinth control valve
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 32-2 ~ figure 32-4)

 

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. 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