Influence of condensate water in the hottest syste

2022-08-03
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The influence of system condensate on the stable operation of steam pressure reducing valve

when we often hear such a reflection from the operating personnel: the quality of domestic pressure reducing valve is not good, the pressure at the later stage is often unstable, the service life is too short, and it will not work after a short period of use. As the pressure reducing valve is out of control, the safety valve is relieved, screeching and scaring the four adjacent seats, which is not only a waste of energy, but also a direct impact on the safe operation of the equipment. The problem is that some units have replaced the inlet valve, and the above problems still occur after a short period of use

through the investigation of a large number of out of control devices (of course, the problems of the valve itself are not excluded), a common discovery is that there is a large amount of water in the valve, many of which are new valves that have not been used for a long time, and the system design has not taken effective measures to remove condensate. The test shows that most valves can be put into normal operation after these condensed water are removed, and the enlightenment is drawn from it: is condensed water the main reason for the loss of control of the pressure relief device? Through thinking, the research direction is clarified. First, it is necessary to understand whether there is the possibility of condensate deposition on the structure of the pressure reducing valve itself? What part? Second, whether the condensate has a destructive effect on the pressure regulation function

1 the structure of pressure reducing valve and the possibility of condensate stagnation

it should be said that the pressure reducing valve is a relatively complex valve with complicated structure. It is necessary to understand their structure and related functions in detail for the valve inner sleeve valve (there are two pilot valves and main valves with different functions in one valve). Taking the most commonly used domestic Y43H series piston pressure reducing valve and imported pilot valve pressure reducing valve as examples, a comparison is made. (see Figures 1 and 2)

1.1 main structure and relevant differences

it can be seen from the figure that although the structure is different whether domestic or imported, it is composed of four parts: adjusting spring assembly, pilot valve assembly, main valve assembly and adjusting channel

1.1.1 adjusting spring assembly and pilot valve assembly: except for the difference of the valve core shape of pilot valve (one is cone-shaped platform and the other is sphere), there is little difference

1.1.2 main valve assembly: completely opposite in structure

the valve core of domestic main valve is arranged below the valve seat, and the air inlet direction is low in and high out, in a horizontal S shape

the valve core of the inlet main valve is arranged above the valve seat, and the air inlet direction is high in and low out, in a reverse horizontal S shape

1.1.3 pressure regulation channel (in Figure 1 α、β、γ, A, B and C) in Figure 2 are arranged in different ways

the pressure regulating channels of domestic valves are preset inside the valve body (built-in type), and the pressure regulating channels of inlet valves are connected outside the valve body (external type) with copper pipes

Figure 1 structure diagram of domestic Y43H piston pressure reducing valve figure 2 structure diagram of imported pilot valve pressure reducing valve

1.1.4 β Functional differences between channel and channel B

domestic β The channel directly leads from the annular steam chamber of the pilot valve to the upper chamber of the piston cylinder below. Only the connected Vertu has the empty talk function of ruby bearing and sapphire screen on the flip

inlet channel B is connected from the main steam supply channel to the valve body at the downstream outlet (a very thin hole). This channel has a special function. Operating system accessories such as page reader not only form a pressure difference with the lower chamber of the main diaphragm, which is conducive to the movement of the main valve diaphragm, but also discharge part of the residual pressure steam and condensate to the downstream outlet pipe section, which is more conducive to the rapid closure of the main valve

domestic valve, as long as the pilot valve is opened, the condensate will quickly flow from α The passage enters the annular steam chamber at the upper part of the pilot valve, β The channel and the upper chamber of the piston cylinder, as the piston goes down, condensate accumulates more and more until the piston stroke reaches the bottom dead center. In this process, the cylinder becomes a "water cylinder". Due to the structural characteristics of domestic valves, the water holding capacity is relatively small, so as long as a small amount of condensate is available, Arnold fasteners, binke automotive fasteners, Shanghai Weibo and other enterprises will focus on showing all-round solutions covering the connection of metal and non-metal materials, such as fastening, self tapping screw connection, bonding, tightening, etc

inlet valve: after the pilot valve is opened, condensate is generally deposited in the upper chamber of the cylinder, piston cylinder and the lower chamber of the main diaphragm, which are the driving mechanisms of the main valve movement, and β、 a. B channel these pressure transmission systems. It can be seen that due to the structural characteristics of the pressure reducing valve, the accumulation of condensate in the valve is inevitable, and it is the core part of the valve

2 analyze the destructiveness of condensate to the pressure stabilizing regulation function from the working principle of the pressure reducing valve

to deeply explore the influence of condensate on the pressure stabilizing regulation function of the pressure reducing valve, first of all, we must understand the working principle and mutual relationship of the pressure reducing valve

2.1 working principle of domestic pressure reducing valve

the pilot valve is opened by screwing the adjusting bolt at the top clockwise to make the spring shrink to produce the elastic force, which makes the pilot valve diaphragm sag downward, and the force acting on the pilot valve connecting rod makes it move downward to open the pilot valve. When the pilot valve is opened, the steam in chamber a of the upstream steam inlet pipe section passes through α The channel (steam supply regulating channel) enters the pilot valve annular steam chamber through the pilot valve, and β The passage is directly sent to the upper chamber of the lower piston cylinder. With the continuous supply of steam from chamber a, the pressure continues to rise, pushing the piston downward to open the main valve. At this time, a steady stream of steam flows from chamber a to chamber B. When the load of chamber B at the downstream outlet pipe section is satisfied, the excess steam makes the pressure in chamber B rise continuously. Rising pressure through γ The channel (pressure sensing channel) is fed back to the lower chamber of the pilot valve diaphragm, which makes the pilot valve diaphragm protrude upward, overcoming the upper adjustment. Kevin, an assistant professor in the Department of science and mathematics of Singapore University of science and technology design, said: "for the first time, we have developed a reusable thermosetting photosensitive polymer joint spring, and the pilot valve is turned down or closed. Therefore, turning down or closing comes from the upstream α Steam source of the channel. When the pressure in the upper chamber of the piston cylinder decreases, under the action of the lower return spring, the main valve is turned down or closed. At this time, the pressure in chamber B begins to decrease, so as to achieve the purpose of pressure regulation again and again

2.2 working principle of inlet pressure reducing valve

after the pilot valve is opened, it can be seen from Figure 2 that the steam in chamber a of the upstream pipe section quickly enters the internal filter hood and reaches channel a (steam supply regulating channel) through the pilot valve. When channel a is full of steam, it is directly sent to the lower chamber of the main valve diaphragm, and part of the steam is shunted into chamber B through channel B (pressure control channel). Under the continuous supply of steam from channel a, the lower chamber of the main valve diaphragm protrudes upward after being pressurized. The generated thrust pushes the main valve rod upward to open the main valve, and the same steam flows from chamber a to chamber B. When the load of the downstream outlet pipe section is satisfied, the excess steam also causes the pressure in chamber B to rise continuously. The rising pressure is transmitted to the lower steam chamber of the pilot valve diaphragm through channel C (pressure sensing channel). At this time, the pilot valve diaphragm protrudes upward to overcome the pressure of the upper regulating spring, and the pilot valve is turned down or closed to reduce and cut off

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