JP5821888B2 - Steam pressure differential energy recovery system - Google Patents

Description

  The present invention relates to a steam pressure difference energy recovery system for recovering pressure difference energy (steam pressure difference energy) generated by the pressure reduction of steam when the high pressure steam is decompressed and supplied to the steam demand facility.

  In a plant (steam demand facility) that uses steam, high pressure (for example, 1.2 MPa) steam generated by a boiler is decompressed by a pressure reducing valve, and low pressure (for example, 0.8 MPa) steam is supplied to the steam demand facility. However, when the pressure of the steam is reduced by the pressure reducing valve, the steam pressure difference energy generated by the pressure reduction of the steam is discarded. Therefore, it is desired to recover the steam pressure difference energy.

  Therefore, in Patent Document 1, high-pressure steam generated by a boiler is supplied to a steam expander to expand and decompress the high-pressure steam, and the decompressed low-pressure steam is supplied to the steam demand facility, and the expansion energy of the steam (steam pressure difference) It has been proposed to recover steam pressure difference energy by driving a steam expander driven air compressor (air compressor driven by a steam expander) using energy.

JP 2009-257119 A

  However, in the method described in Patent Document 1, if the temporal fluctuation range of the steam demand in the steam demand facility (hereinafter also simply referred to as “demand amount”) is large, the steam expander is out of the operable range. In other words, the steam expander cannot perform expansion / decompression, and the steam pressure difference energy may not be recovered.

  The present invention has been made in view of the circumstances as described above. When the high-pressure steam is depressurized and supplied to the steam demand facility, the steam demand amount in the steam demand facility has a large fluctuation range over time. Even if it exists, it aims at providing the steam pressure difference energy recovery system which can collect | recover steam pressure difference energy appropriately.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors are able to cope with a large flow rate of steam when the time fluctuation width of the steam demand in the steam demand facility is large. The idea was that it should be operated in combination with a turbo steam expander that can be operated and a positive displacement steam expander with a wide operating range. At that time, once the turbo steam expander is stopped, drainage and warm-up operation are required to restart the turbo steam expander, resulting in a time loss of 2-3 hours. The type steam expander may be operated to adjust the excess / deficiency with the positive displacement steam expander.

  The present invention is based on the above idea and has the following features.

[1] A steam pressure difference energy recovery system for recovering the steam pressure difference energy generated by the pressure reduction of the steam when the high pressure steam is decompressed and supplied to the steam demand facility,
Turbo-type steam expander for expanding / depressurizing steam, turbo-type steam expander driving device driven by turbo-type steam expander, positive-displacement steam expander for expanding / depressurizing steam, and positive-displacement steam expander The volumetric steam expander drive device driven by the valve, the switching valve for switching the steam flow, and the intake amount of the turbo steam expander within the operable range according to the demand amount of the steam demand facility A steam pressure difference energy recovery system comprising: a control device that controls a flow of steam.

[2] The control device includes:
When the demand amount of the steam demand facility exceeds the operable range of the turbo steam expander, both the turbo steam expander and the positive displacement steam expander are inhaled and each decompressed steam is Supplying steam demand equipment,
When the demand amount of the steam demand facility is below the operable range of the turbo type steam expander, the turbo type steam expander is inhaled within the operable range, and the demand amount of the decompressed steam is reduced. The steam pressure difference energy recovery system according to [1], wherein the steam pressure difference energy supply system supplies the steam to the steam demand facility and causes the depressurized steam to be sucked into the positive displacement steam expander.

  In the present invention, when the high-pressure steam is decompressed and supplied to the steam demand facility, the steam pressure difference energy is appropriately recovered even when the demand fluctuation amount in the steam demand facility is large over time. Can do.

It is a figure showing an outline of a steam pressure difference energy recovery system concerning one embodiment of the present invention. It is a figure explaining the driving | running state in one Embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an outline of a steam pressure difference energy recovery system according to an embodiment of the present invention.

  As shown in FIG. 1, the steam pressure difference energy recovery system according to an embodiment of the present invention reduces the pressure of high-pressure steam generated by a boiler (not shown) when supplying steam to the steam demand facility 40. It is for recovering steam pressure difference energy generated by decompression, and is a turbo steam expander 1 that expands and decompresses the intake steam, a positive displacement steam expander 2 that expands and decompresses the intake steam, A control device 8 for controlling the flow is provided.

  Here, although the direct piping 30 which goes straight from the boiler to the steam demand facility 40 is installed and the pressure reducing valve 11 is provided in the direct piping 30, the pressure reducing valve 11 is normally closed.

  An intake main pipe 21 branched from the direct pipe 30 upstream of the pressure reducing valve 11, a first intake pipe 22 branched from the intake main pipe 21 and connected to the intake side of the turbo steam expander 1, A second intake pipe 23 connected from the tip of the pipe 21 to the intake side of the positive displacement steam expander 2, and a first exhaust connected from the exhaust side of the turbo steam expander 1 to the direct pipe 30 downstream of the pressure reducing valve 11. A bypass pipe 25, a bypass pipe 25 branched from the first exhaust pipe 24 and connected to the intake main pipe 21 on the downstream side of the branch point of the first intake pipe 22, and a direct pipe 30 from the exhaust side of the positive displacement steam expander 2. Are provided with a second exhaust pipe 26 connected downstream of the pressure reducing valve 11 and a discharge pipe 27 branched from the second exhaust pipe 26.

  Further, the first flow rate control valve 3 installed in the first intake pipe 22, the second flow rate control valve 4 installed in the second intake pipe 23, and the connection point between the branch point of the first intake pipe 22 and the bypass pipe 25. The first switching valve (open / close valve) 5 installed in the intake main pipe 21 between the points, the second switch valve (open / close valve) 6 installed in the bypass pipe 25, and the discharge from the second exhaust pipe 26. A connection between the first exhaust pipe 24 and the third switching valve 7 that is installed at the branch point of the pipe 27 and switches the flow of the steam to the downstream side of the second exhaust pipe 26 (steam demand facility 40 side) and the discharge pipe 27 side. And a pressure meter 9 installed in the direct piping 30 downstream of the connection point of the second exhaust piping 26 and a flow meter 10 installed in the first intake piping 22 downstream of the first flow rate control valve 3. ing. Among these, the pressure gauge 9 and the flow meter 10 send each measured value to the control device 8 as a signal. On the other hand, the first flow control valve 3, the second flow control valve 4, the first switching valve (open / close valve) 5, the second switch valve (open / close valve) 6 and the third switch valve 7 are signals from the control device 8. Their operation is controlled. A dotted line in FIG. 1 indicates a case where a signal is input to the control device 8, and a one-dotted line indicates a case where a signal is output from the control device 8.

  Although not shown, the turbo steam expander 1 is connected to a steam expander drive device (turbo steam expander drive device) driven by the turbo steam expander 1 so that a positive displacement steam expander is connected. A steam expander driving device (a positive displacement steam expander driving device) driven by the positive displacement steam expander 2 is connected to the machine 2. Examples of the steam expander driving device include an air compressor and a generator driven by the steam expander.

  Thereby, in the turbo type steam expander 1 and the positive displacement steam expander 2, the sucked high-pressure steam expands and is depressurized by rotating the turbine to work, and the exhausted depressurized steam is supplied to the steam demand facility 40. While being supplied, a steam expander driving device (air compressor, generator, etc.) is driven by the rotational force (driving force) of the turbine, whereby the steam pressure difference energy is recovered.

  At that time, the turbo-type steam expander 1 is always operated with respect to the temporal fluctuation of the demand amount in the steam demand facility 40, and the excess or deficiency is adjusted by the positive displacement steam expander 2, and the control device 8 Controls the flow of steam so that the intake air amount of the turbo type steam expander 1 falls within the operable range of the turbo type steam expander 1.

  That is, in this embodiment, for example, as shown in FIG. 2, the intake capacity (operable range) of the turbo steam expander 1 is 5 to 50 t / h, and the demand amount of the steam demand facility 40 is 2 When fluctuating between ˜55 t / h, if the demand amount is within the operable range of the turbo steam expander 1 (region I: 5 to 50 t / h), the demand amount is that of the turbo steam expander 1. When the operating range is exceeded (area II: more than 50 t / h), the demand is below the operable range of the turbo steam expander 1 (area III: less than 5 t / h). The control device 8 controls the flow of steam as follows.

(A) When the demand amount of the steam demand facility 40 is in the region I After the first switching valve 5 and the second switching valve 6 are closed and the third switching valve 7 is set to the steam demand facility 40 side or is closed Thus, by adjusting the opening degree of the first flow rate control valve 3, high-pressure steam corresponding to the demand amount passes through the main intake pipe 21 and the first intake pipe 22 and is sucked into the turbo type steam expander 1, and the turbo The decompressed steam that has been expanded and decompressed by the type steam expander 1 and exhausted is supplied to the steam demand facility 40 through the first exhaust pipe 24 and the direct pipe 30.

(B) When the demand amount of the steam demand facility 40 is region II The first switching valve 5 is opened, the second switching valve 6 is closed, and the third switching valve 7 is set to the steam demand facility 40 side. By adjusting the opening degree of the first flow rate adjusting valve 3 and the opening degree of the second flow rate adjusting valve 4, within the operable range of the turbo type steam expander 1 (for example, the operation) The high-pressure steam of the upper limit of the allowable range) passes through the intake main pipe 21 and the first intake pipe 22 and is sucked into the turbo-type steam expander 1, and is decompressed and decompressed by the turbo-type steam expander 1 and exhausted. Is supplied to the steam demand facility 40 through the first exhaust pipe 24 and the direct pipe 30, and the high-pressure steam that is insufficient with respect to the demand amount is passed through the intake main pipe 21 and the second intake pipe 23 to increase the volume. Type steam expander 2 is inhaled and expanded and decompressed by positive displacement steam expander 2 The reduced-pressure steam exhausted in this manner is supplied to the steam demand facility 40 through the second exhaust pipe 26 and the direct pipe 30.

(C) When the demand amount of the steam demand facility 40 is in the region III, the first switching valve 5 and the second switching valve 6 are opened, and the third switching valve 7 is set to the discharge pipe 27 side, and then the first flow control valve 3 and the opening of the second flow rate control valve 4, high-pressure steam within the operable range (for example, the operable lower limit amount) of the turbo steam expander 1 is supplied to the intake main pipe 21 and the second flow control valve 4. The reduced pressure steam corresponding to the demand amount out of the reduced pressure steam exhausted by passing through the first intake pipe 22 and sucked into the turbo steam expander 1 and expanded and decompressed by the turbo steam expander 1 is supplied to the first exhaust pipe 24. And passing through the direct piping 30 to supply to the steam demand facility 40, and the reduced pressure steam that is surplus with respect to the demand amount is passed through the bypass piping 25, the main intake piping 21, and the second intake piping 23 to be positive displacement type. The steam expander 2 is inhaled and further expanded by the positive displacement steam expander 2. After recovering the vapor pressure difference energy by reducing the pressure, the exhausted reduced-pressure steam is discharged outside the system through the second exhaust pipe 26 and the discharge pipe 27.

  In the case of (a), if necessary, as in the case of (b), high-pressure steam is expanded and depressurized in both the turbo steam expander 1 and the positive displacement steam expander 2, The reduced-pressure steam may be supplied to the steam demand facility 40.

  Further, in the above, it is confirmed by the pressure gauge 9 and the flow meter 10 that the pressure and flow rate of the decompressed steam supplied to the steam demand facility 40 are at desired values. If the desired value is not reached, the opening of the first flow control valve 3 and the opening of the second flow control valve 4 are further adjusted.

  In addition, when the turbo type steam expander 1 or the like breaks down and an abnormal situation occurs in which the reduced pressure steam cannot be supplied to the steam demand facility 40, the decompression valve 11 of the direct pipe 30 is operated to supply the decompressed steam to the steam demand facility. 40 directly.

  In this way, in this embodiment, even if the demand amount of the steam demand facility 40 is outside the operable range of the turbo steam expander 1, the steam flow is controlled so that the turbo steam expander 1 Since the intake air amount is within the operable range of the turbo steam expander 1 and the excess / deficiency is adjusted by the positive displacement steam expander 2, the steam pressure difference energy can be recovered appropriately. it can.

  Incidentally, as in the prior art (Patent Document 1), in FIG. 1, instead of using the positive displacement steam expander 2, only the turbo steam expander 1 is used to recover the steam pressure difference energy. In this case, in region II in FIG. 2, the portion exceeding the operable upper limit value 50 t / h of the turbo type steam expander 1 must be reduced by the pressure reducing valve 11 and supplied to the steam demand facility 40. The steam pressure difference energy cannot be recovered.

  Further, in region III in FIG. 2, since the turbo type steam expander 1 cannot be operated, the pressure must be reduced by the pressure reducing valve 11 and supplied to the steam demand facility 40, so that the steam pressure difference energy can be recovered. Can not. Moreover, once the turbo steam expander 1 is stopped, drainage and warm-up operation are required to restart the turbo steam expander 1, and a time loss of 2 to 3 hours occurs. Even if the demand amount becomes the region I or the region II, the steam pressure difference energy cannot be recovered.

  As described above, the present invention can provide an advantageous effect over the prior art.

DESCRIPTION OF SYMBOLS 1 Turbo type steam expander 2 Positive displacement steam expander 3 1st flow control valve 4 2nd flow control valve 5 1st switching valve 6 2nd switching valve 7 3rd switching valve 8 Control apparatus 9 Pressure gauge 10 Flowmeter 11 Pressure reduction Valve 21 Intake main pipe 22 First intake pipe 23 Second intake pipe 24 First exhaust pipe 25 Detour pipe 26 Second exhaust pipe 27 Release pipe 30 Direct pipe 40 Steam demand facility

Claims (2)

A steam pressure difference energy recovery system for recovering the steam pressure difference energy generated by the pressure reduction of the steam when the high pressure steam is decompressed and supplied to the steam demand facility,
Turbo-type steam expander for expanding / depressurizing steam, turbo-type steam expander driving device driven by turbo-type steam expander, positive-displacement steam expander for expanding / depressurizing steam, and positive-displacement steam expander The volumetric steam expander drive device driven by the valve, the switching valve for switching the steam flow, and the intake amount of the turbo steam expander within the operable range according to the demand amount of the steam demand facility A steam pressure difference energy recovery system comprising: a control device that controls a flow of steam. The controller is
When the demand amount of the steam demand facility exceeds the operable range of the turbo steam expander, both the turbo steam expander and the positive displacement steam expander are inhaled and each decompressed steam is Supplying steam demand equipment,
When the demand amount of the steam demand facility is below the operable range of the turbo type steam expander, the turbo type steam expander is inhaled within the operable range, and the demand amount of the decompressed steam is reduced. The steam pressure difference energy recovery system according to claim 1, wherein the steam pressure difference energy recovery system is configured to supply the steam to the steam demand facility and allow the excessively decompressed steam to be sucked into the positive displacement steam expander.

Images