DE102009041222A1 - Turbo machine i.e. turbo compressor, has monitoring device for detecting position and flow rate parameter of check valve and outputting signal based on position and parameter, where position indicates position of flap - Google Patents

Abstract

The turbo machine i.e. turbo compressor (2), has a monitoring device (1) for detecting a position and a flow rate parameter of an automatic check valve (3) and outputting a signal (S) based on the position and the parameter during operation. The valve has a spring- and/or weight-loaded movable flap (3.1) that is automatically closed in a closing direction during return flow of process gas. The position indicates a position (phi) of the flap, and the flow rate parameter includes mass flow rate (m) or volume flow rate of the gas through the turbo machine or pressure difference in the valve. An independent claim is also included for a method for monitoring a turbo machine.

Description

The invention relates to a turbomachine, in particular a compressor, with a non-return valve and a monitoring device for monitoring, such a non-return valve and a monitoring method.

For example, from the DE 38 11 232 A1 a compressor with a downstream non-return valve and a arranged between the compressor and check valve surge limit control valve is known. For this purpose, weight-loaded check valves are known, which close automatically in the non-flow state due to asymmetric storage of the flap and an additional weight. While a flow in the opening direction can open the flap against intrinsic and additional weight, an undesirable backflow, now supported by own weight and additional weight, pushes the flap against attacks, so that it shuts off the return flow.

Although such valves work energy-free and usually quite reliable, various disturbances can occur: For example, frictional forces in the bearings or seals of the flap counteract a provision. In particular, in a fully open position, in which the flap is substantially symmetrically flowed with respect to its axis of rotation, a provision of the flap against the attacks is essentially only effected by their own and additional weight, the substantially symmetrical (back) flow support the closing hardly in this position. This may at higher friction, especially higher static friction by caking, deposits, etc., may no longer be sufficient, so that the check valve unintentionally remains in its open position. This can lead to considerable damage to the turbomachine.

Frequently, however, such turbomachines are designed for several years of continuous operation, so that such a malfunction of the check valve, which previously can only be detected when stopping the process, remains undetected.

Object of the present invention is therefore to increase the safety of a turbomachine.

To solve this problem, a turbomachine with an automatic check valve according to the preamble of claim 1 is further developed by its characterizing features. Claim 6, such a non-return valve, claims 7 a corresponding verification process under protection. The subclaims relate to advantageous developments.

In the case of a properly functioning non-return valve, there is an association between a position of the non-return valve, for example the angular position of a preferably spring- and / or weight-loaded movable flap, and a flow rate of the non-return valve, in particular a mass or volume flow. Such a relationship is preferably stored in the form of a polygon.

According to the invention, it is now proposed to make use of this relationship by detecting actual positions and flow variables of the non-return valve during operation. Obey this, if appropriate, taking into account the corresponding tolerances, not the given context, as for example, despite higher mass flow a festgebackene or stiff check valve does not open or closes accordingly with decreasing mass flow accordingly, a malfunction can be detected early and activated or a corresponding message signal Enable signal are disabled. The present invention thus permits one, preferably continuous or periodic, monitoring of the function of the check valve during operation by detecting valve movement due to minor changes in process conditions.

The position of the check valve directly determines their free, ie flow-through cross-section. This determines depending on the pressure difference between the inlet and outlet of the valve volume flow, which in turn determines the mass flow through the valve as a function of pressure, temperature and gas composition. For example, in compressors for surge limit control, the flow rate through the compressor is determined as the inlet flow rate, so in a preferred embodiment, this or inlet mass flow, which is proportional to flow rate at constant inlet conditions, can be used as the flow size. Likewise, it is also possible to use a flow rate sensed downstream of the check set. Preferably, the flow rate, in particular the mass or volume flow, externally, for example in an upstream compressor or an upstream or downstream flow measuring device determined. In a preferred embodiment, the mass flow determined at an external measuring point, preferably by correction with pressure and / or temperature values, which are determined before and / or after the non-return valve, is converted into a volume flow.

mit
m = Massenstrom durch die Rückschlagarmatur,
z = Kompressibilitätszahl des Prozessgases,
R = Gaskonstante des Prozessgases,
T = Temperatur am Ein- oder Austritt,
A(φ) = stellungsabhängiger freier Querschnitt

= stellungsabhängiger Reib- bzw. Widerstandsbeiwert der Armatur
p_i, p_i+1 = Drücke am Ein- und Austritt
ein Zusammenhang zwischen der Stellung φ der Rückschlagarmatur und dem Massenstrom m als Durchflussgröße zugrundegelegt werden. Der stellungsabhängige Reib- bzw. Widerstandsbeiwert

beschreibt den Energieverlust über der Rückschlagarmatur, die Differenz (p_i – p_i+1) den Druckverlust.In a preferred embodiment, as an alternative or in addition to a detected pressure loss over the non-return valve, an energy loss, in particular position-dependent, over the non-return valve is taken into account. For this purpose, for example, based on the context

With
m = mass flow through the non-return valve,
z = compressibility number of the process gas,
R = gas constant of the process gas,
T = temperature at the inlet or outlet,
A (φ) = position-dependent free cross-section

= position-dependent coefficient of friction or resistance of the valve
p _i , p _{i + 1} = pressures at the inlet and outlet
a relationship between the position φ of the check valve and the mass flow m are used as the flow quantity. The position-dependent friction or drag coefficient

describes the energy loss over the check valve, the difference (p _i - p _{i + 1} ) the pressure loss.

In a preferred embodiment, a desired value φsetpoint is determined from the detected mass flow m on the basis of the relationship specified by (1) and compared with the detected position φ. If a difference | φsoll - φ | exceeds a predetermined limit, a message signal can be output. An alarm signal may also be realized by a non-output of a release signal, the absence of which as well as a message signal indicates a malfunction of the check valve.

Some valves have a significant static friction even when in proper condition. To monitor such check valves, it is advantageous to specify the limit so that a persistence of the valve with smaller changes in the flow size is not interpreted as a faulty deviation.

In order to take into account a position-dependent behavior of the non-return valve, in a preferred embodiment, the predetermined limit depends on the position of the non-return valve. For example, due to the reduced flow area at a more open check set the limit may be greater, since here with small changes in the mass flow (haft) friction and fluidic conditions resulting smaller position changes.

In particular, in order to take account of a friction and inertia-related overrun or a dead time of the non-return valve, in a preferred embodiment, a message signal is output only when the difference exceeds the predetermined limit value for a predetermined minimum time.

If a variable or adjustable intermediate outlet, for example in the form of the above-explained surge limit control valve, is arranged between the turbomachine and the non-return valve or between stages of the turbomachine, the variable or adjustable volume or mass flow branched off here is branched off in a preferred embodiment, preferably taking into account further factors such as pressure and / or temperature before and / or after the intermediate outlet, taken into account. This can be done, for example, by estimating the diverted volume or mass flow, based for example on the position of the intermediate outlet, and subtracting it from the entry volume or mass flow into the compressor, or by having at least partially opened intermediate outlet , a deviation from the relationship between the position and the flow rate is not considered faulty.

Another aspect of the present invention, which may be combined with one or more of the features discussed above, is based on the following principle: In a properly functioning check valve prevails in stationary or quasi-stationary state, a balance of forces and moments between a closing force and a closing torque, which Weight, spring and / or others Closing forces results and the check valve seeks to close, for example, a restoring moment on a movable flap, and an opening force or an opening moment, which results from flow forces and seeks to open the check valve, such as a moment on the eccentrically mounted flap due to the pressure difference above the non-return valve. Opening and / or closing force or opening and / or closing torque are dependent on the position of the check valve, such as a movable flap, closing force or torque are dependent on the flow and thus a flow rate such as the pressure difference.

Thus, preferably, empirically or computationally, different positions can again be associated with an associated flow quantity. For example, on the basis of the moment equilibrium for an eccentric movable flap for different pressure differences and the resulting opening moment, that flap position can be determined in which the closing moment resulting from weight, spring and / or other closing forces balances this opening moment.

By now determined from this given relationship between position and flow rate, such as the differential, based on the detected position, a target value for the flow rate and compared with the detected flow size or vice versa based on the detected flow rate determined a target value for the position and is compared with the detected position, a malfunction of the check valve can be detected. For example, if a movable flap jammed, these clamping forces interfere with the torque balance, d. H. the detected position of the flap does not correspond to that which would set with trouble-free flap under the balance of flow-induced opening and weight or spring-induced closing forces, and thus not the given context for a properly functioning check valve.

Again, by correcting with the temperature before and / or behind the check valve, the accuracy of the monitoring can be improved.

Further advantages and features emerge from the subclaims and the exemplary embodiment. This shows, partially schematized, the only one

1 A turbomachine according to an embodiment of the present invention.

1 shows a compressor 2 with a non-return valve 3 , which is to prevent a backflow of process gas into the compressor. This is a flap 3.1 asymmetrically mounted and with an additional weight 3.2 weighted, so that own weight and additional weight shut the door 3.1 Reset against attacks. In an alternative, not shown embodiment, the flap is formed twice eccentric.

A backflow in the reverse direction (from right to left in 1 ) supports the closing movement, allowing the check valve 3 locks in this direction. By contrast, the process gas flows in the desired direction from the compressor 2 through the non-return valve 3 (from left to right in 1 ), it shuts the flap 3.1 against own weight and additional weight by an angle φ. This determines depending on the geometry of the check valve 3 the in 1 indicated free, permeable cross-section A, for example, in a rectangular flap with the base A ₀ : A (φ) = A ₀ (1 - cosφ) (2)

= 0,5 und

= 4,0.The resistance coefficient varies, for example, between

= 0.5 and

= 4.0.

Before or after the check valve 3 can appropriate pressure and temperature sensors 5.1 . 5.2 be arranged, the pressures p _i , p _{i + 1} at the inlet and outlet of the check valve 3 and detect the temperature T at the inlet and to a monitoring device 1 transmit, which carries out a monitoring according to the invention. A mass flow m, for example, from an intake flow under consideration of pressure and temperature at the compressor inlet or by a flow sensor 5.2 behind the non-return valve 3 determined and as well as the position φ the flap 3.1 also to the monitoring device 1 transfer.

A(φsoll) = A₀(1 – cosφsoll) (2') genügt. Mit diesem wird die erfasste Stellung φ verglichen. Übersteigt die Differenz |φ – φsoll| für eine vorgegebene Zeitdauer bzw. für eine vorgegebene Anzahl von Auswertungen einen Grenzwert G(φ), gibt die Überwachungseinrichtung 1 ein Meldesignal S aus, welches eine Fehlfunktion der Rückschlagarmatur 3 anzeigt. Der Grenzwert G ist dabei stellungsabhängig gewählt und nimmt im Ausführungsbeispiel von φ = 0° bis φ = 90° zu. Denn bei nahezu geöffneter Klappe 3.1 (φ ≈ 90°) beaufschlagt der Massenstrom durch die Rückschlagarmatur 3 die Klappe 3.1 nur mit einem geringen Drehmoment, so dass diese – insbesondere bei großer Haftreibung der Klappe 3.1 – auf geringfügige Änderungen des Massenstroms nicht oder nur mit geringen Stellungsänderungen reagiert. Dementsprechend dürfen bei funktionstüchtiger Rückschlagarmatur 3 in der Nähe ihrer maximal offenen Stellung (φ ≈ 90°) größere Differenzen |φ – φsoll| auftreten.The monitoring device determines from these measured values 1 according to equations (1), (2), for example by interpolation of corresponding table values or numerical evaluation, a desired value φsoll, the

A (φsoll) = A ₀ (1 - cosφsoll) (2 ') enough. With this the detected position φ is compared. Exceeds the difference | φ - φsoll | for a given period of time or for a given number of evaluations a limit G (φ), the monitoring device outputs 1 an alarm signal S off, which is a malfunction of the check valve 3 displays. The limit value G is selected as a function of the position and increases in the exemplary embodiment from φ = 0 ° to φ = 90 °. Because at almost open flap 3.1 (φ ≈ 90 °) acts on the mass flow through the check valve 3 the flap 3.1 only with a low torque, so this - especially at high friction of the flap 3.1 - Responding to minor changes in mass flow or only with small changes in position. Accordingly, with a functional non-return valve 3 near its maximum open position (φ ≈ 90 °) larger differences | φ - φsoll | occur.

The operating condition of the compressor is approaching 2 a surge limit line, a surge limit control at least partially opens a surge limit control valve 4 to a part of the process gas to the suction side of the compressor 1 due or discharged (not shown) into the environment. In a modification, not shown, the intermediate outlet is formed as a passage valve in the Umblaseleitung. Accordingly, the mass flow from the compressor is reduced 2 to check valve 3 , Is the input mass or volume flow of the compressor 1 used to determine the flow quantity m according to (1 '), this value is reduced by an amount Δ, which is based on the position of the surge limit control valve, preferably taking into account further factors such as pressure and / or temperature before and / or behind the intermediate outlet, is estimated. In an alternative embodiment, at least partially open surge limit control valve 4 , ie a concern of a signal Δ at the monitoring device 1 , from this independent of the difference | φ - φsoll | no message signal S is output, since a difference exceeding the limit value G may result from the lower mass flow. In a further modification, it is also possible to use different limit values G (Δ) as a function of the different mass flows and thus also the function of the non-return valve during a surge limit control 3 be checked.

In an alternative embodiment of the design data of the check valve, in particular mass and lever arm of flap 3.1 and additional weight 3.2 to the axis of rotation, for different positions φ determined a closing torque about the axis of rotation. For each of these positions may depend on the design data, in particular the effective area of the flap 3.1 , a pressure difference (p _i - p _{i + 1} ) are determined via the non-return valve, in which the resulting opening moment balances the closing moment. Thus, different positions φ discretely, for example in the form of a table, or functionally, for example in the form of a polygonal line, values of the flow variable in the form of the pressure difference (p _i - p _{i + 1} ) can be assigned.

For checking now the actual position φ of the flap 3.1 From this, the associated pressure difference is determined in accordance with the relationship given for a properly functioning non-return valve and with that of the sensors 5.1 . 5.2 detected pressure difference (p _i - p _{i + 1} ) compared. If the target pressure difference and the detected pressure difference deviate too much from each other, this indicates that the flap 3.1 for example, jammed, due to friction too stiff or additional weight 3.2 is canceled.

LIST OF REFERENCE NUMBERS

1

monitoring device

2

Turbo compressor

3

check valve

3.1

flap

3.1

additional weight

4

Surge limit control valve

5.1

Pressure and temperature sensor

5.2

Pressure sensor and mass flow detection device

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3811232 A1 [0002]

Claims (15)

Turbomachine, in particular compressor ( 2 ), with an automatic non-return valve ( 3 ), characterized by a monitoring device ( 1 ) for detecting a position (φ) and a flow rate (m) of the check valve, which is arranged to output a signal (S) based on the position and the flow rate. Turbomachine according to claim 1, characterized in that the automatic non-return valve a, in particular spring and / or weight loaded, movable flap ( 3.1 ), whose position (φ) determines a free cross-section (A), and which automatically locks in a reverse flow in a reverse flow. Turbomachine according to one of the preceding claims, characterized in that the flow variable comprises a mass flow (m) or a volume flow (V), in particular by the turbomachine, or a pressure difference across the check valve. Turbomachine according to one of the preceding claims, characterized by a pressure and / or temperature detection device ( 5.1 . 5.2 ) for transmitting data to the monitoring device. Turbomachine according to one of the preceding claims, characterized by an adjustable intermediate outlet, in particular a surge limit control valve ( 4 ), in the turbomachine and / or between the turbomachine and the check valve. Automatic non-return valve ( 3 ) for a turbomachine according to any one of the preceding claims, characterized by a detection device for detecting the position (φ) of the check valve. Method for monitoring a turbomachine, in particular a compressor ( 2 ), with an automatic non-return valve ( 3 ) according to one of the preceding claims, comprising the steps of: detecting the position (φ) of the non-return valve; Detecting the flow rate (m) of the check valve; and outputting the signal (S) based on the position and the flow rate. A method according to claim 7, characterized in that determined from one of the detected position and the detected flow rate (m) based on a predetermined relationship between position and flow rate a setpoint value (φsoll) and with the other (φ) of the detected position and the detected flow size is compared. A method according to claim 8, characterized in that a message signal is output if a difference (| φsoll - φ |) between the determined target value and the other of the detected position and the detected flow rate exceeds a predetermined limit. A method according to claim 9, characterized in that the predetermined limit of the position of the check valve (G (φ)) and / or the position of an adjustable intermediate outlet, in particular a surge limit control valve ( 4 ), between the turbomachine and the check valve (G (Δ)). Method according to one of the preceding claims 9 to 10, characterized in that the message signal is output as soon as the difference between the determined desired value and the other of the detected position and the detected flow rate exceeds the predetermined limit value for a predetermined minimum time. Method according to one of the preceding claims 8 to 11, characterized in that the relationship between position and flow rate is given taking into account, in particular position-dependent, energy loss over the check valve. Method according to one of the preceding claims 8 to 12, characterized in that the signal (S) is output on the basis of a detected pressure loss (p _i - p _{i + 1} ) on the check valve. Method according to one of the preceding claims 8 to 13, characterized in that the relationship between position and flow rate according to

with the mass flow m, the compressibility number z, the gas constant R, the temperature T at the inlet or outlet of the check valve, the position-dependent free cross-section A of the check valve, the, in particular position-dependent, drag coefficient

the non-return valve and the pressures (p _i , p _{i + 1} ) at the inlet and outlet of the check valve is specified. Method according to one of the preceding claims 8 to 14, characterized in that the signal (S) based on an outlet (.DELTA.) From an adjustable intermediate outlet ( 4 ) between the turbomachine and the check valve.

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