JPS6052238B2 - Control method of drive valve in thermo compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a drive valve in a thermocompressor.

A series of systems that supplies steam to the dryer in a paper machine, efficiently discharges condensed drain, and recovers it is called a tray screw system.

Although there are various types of this tray screw system, the present invention relates to a tray screw system called a thermocompressor type. Generally, a dryer section of a paper machine is composed of several dozen dryers, and these dryers are divided into three or four groups, and each group is controlled by the operating pressure of steam. In addition, the vapor pressure (operating pressure) at the paper inlet is low;
The later the dryer group is, the higher the operating pressure becomes. The steam flowing into the dryer is transferred to the drain (
becomes condensed water).

Further, in order to discharge the drain, a pressure difference is created between the steam inlet and the outlet of the dryer, and the drain is discharged together with the steam (referred to as broustle steam). The brochure steam required for discharge is utilized in the front dryer group for effective utilization. If the operating pressure of the Brostle steam discharged from the rear group is lower than the operating pressure used in the front group, the pressure is increased by a thermocompressor.

In a thermocompressor, medium-pressure steam is used as energy when boosting the pressure of Brostle steam in the rear group. 1st
The figure shows a control system diagram of a control valve in a thermocompressor, where 1 is a steam pipe for low-pressure steam generated from a source (not shown), and a supply pipe connected from the steam pipe 1 to the inlet of the first dryer group 2. 3 and a supply pipe 5 connected to the inlet of the second dryer group 4 are branched.

6 is a steam pipe for medium pressure steam generated from a source not shown;
7 is a control valve provided in the middle of the supply pipe 3; 8 is a supply pipe 5;
This is a control valve installed in the middle.

9 is a thermocompressor, one steam inlet is connected to the steam pipe 6 for the medium pressure steam, and a control valve 10 is provided in the middle thereof.

Further, a steam outlet of the thermocompressor 9 is connected to the supply pipe 3 via a pipe 11. 12 and 13 are first and second pressure regulators, which are connected to the control valves 7, 10 and 8 in order to maintain constant operating pressures at the inlets of the first dryer group 2 and the second dryer group 4, respectively. It is provided. 1st
The steam supplied to the dryer group 2 and the second dryer group 4 becomes a drain and is discharged through exhaust pipes 14 and 15, and is led to a first separator 16 and a second separator 17, respectively.

Level controllers 18 and 19 are attached to the first and second separators 16 and 17, respectively, and control valves 20,
21, the amount of drain is regulated to a certain amount or less.

23 and 24 are condensed pumps, 25 and 26 are drain discharge pipes, and the drains in the 11th and second dryer groups 2 and 4 are connected to the discharge pipes 25,
26 to the reboiler room.

27 and 28 are steam pipes provided in the first and second separators 16 and 17, respectively; 29 is a steam pipe connected to the thermocompressor 9, and control valves 30 and 31 are provided in the middle.

Further, the steam pipe 27 is connected to a condenser (not shown), and the steam pipe 28 is connected to a steam pipe 29. 32 and 33 are first and second differential pressure regulators; the regulator 32 controls the differential pressure in the first dryer group 2 and other control valves, and the regulator 33 controls the differential pressure in the first dryer group 4; The control valves 30 and 31 are provided in association with the differential pressure applied thereto.

Further, the control valve 31 is connected to a capacitor (not shown). In the diagram of FIG. 2 showing the relationship between the valve opening degree and the output signal of the controller, the output signal of the valve opening degree is, for example. 0.2
The control valve 10 increases from kg1d to 0.6k91d.
(CV-B) changes from fully closed to fully open, and here the control valve 7 (
CV-A) starts to open and 1.0kgIc! Fully open at l. Further, the control valve 31 (CV-D) changes from fully open to fully closed, and here the control valve 30 (CV-C) changes from fully open to fully closed. However, in the conventional system shown in FIG. 1, the pressure control of the first dryer group 2 is performed by the control valve 10, after which the control valve 7 begins to open.

For this reason, the thermocompressor 9 had the disadvantage of consuming more intermediate pressure steam than necessary. Additionally, in this case, in order to control the differential pressure in the second dryer group 4, it was necessary to create a pressure drop using the regulating valve 30 (if the regulating valve 10 remained fully open, too much differential pressure would be created, so the regulating valve (need to narrow it down to 30). The present invention has been proposed in order to solve the above-mentioned conventional drawbacks, and includes providing a low selector in the control valve of the first dryer group, and associating this with the differential pressure control/meter of the second dryer group. In addition to providing a reversing device, each control valve is made to move completely at ★, and the control valve of the first dryer group has the opening degree necessary for the differential pressure between the second dryer group and the pressure in the first dryer group. It is an object of the present invention to provide a method for controlling a drive valve in a thermocompressor, which is capable of controlling the opening degree to the lower side of the required opening degree and preventing intermediate-pressure steam from being consumed more than necessary.

The present invention will be described below with reference to the embodiments shown in the drawings. In FIG. 3, reference numeral 34 is a steam pipe for low-pressure steam generated from a source (not shown), and the steam pipe 34 is connected to the inlet of the first dryer group 35. The supply pipe 36 and the supply pipe 39 connected to the inlet of the second dryer group 38 are branched.

Reference numeral 37 denotes a steam pipe for medium-pressure steam generated from a source (not shown).

Further, control valves 40 (C
VA) and 41 (CV) are provided, and a thermocompressor 43 is connected to the supply pipe between the control valve 40 and the first dryer group 35 via a pipe 42. 44 is a control valve provided in the middle of the steam pipe 37.

45 and 46 are first and second pressure regulators, which control valves 40 and 4 of the first dryer group 35 and the second dryer group 38, respectively.
4 and 41.

47 is a first separator, 48 is a second separator, the first separator 47 and the first dryer group 35 are connected by a drain discharge pipe 49, and the second separator 48 and the second dryer group 38 are connected by a drain discharge pipe 50. connected with.

51 and 52 are condensed pumps, 53 and 54 are control valves, and the pump 51 and the control valve 53 are connected to the first separator 4.
The pump 52 and the control valve 54 are provided in the middle of a discharge pipe 55 that connects the second separator 7 and a boiler room (not shown).
8 and a boiler room (not shown).

Level controllers 57 and 58 are attached to the first separator 47 and the second separator 48 in relation to the control valves 53 and 54, respectively.

59 is a steam pipe provided in the first separator 47 and connected to a condenser (not shown); 60 is a steam pipe provided in the second separator 48; the steam pipe 60 is connected to the steam inlet at the other end of the thermocompressor 43; A control valve 62 is provided in the middle of the tied steam pipe 61, and a control valve 6 connected to a condenser (not shown) is provided on the extension of the steam pipe 61.
3 is provided.

The above is the same as the system shown in FIG. 64 is a low selector provided between the pressure regulator 45 and the control valve 44; 65 and 66 are first and second differential pressure regulators; The regulator 66 is provided to correlate the differential pressure in the second dryer group 38 with the regulating valves 62 and 63.

Further, an inverter 67 is provided between the differential pressure regulator 66 and the low selector 64, and the differential pressure regulator 66 is also associated with the control valve 44. Next, the operation of the embodiment configured as described above will be explained. Low pressure steam flows from the steam pipe 34 through the supply pipes 36 and 39 to the first and second dryer groups 35 and 38, respectively. The control valves 40 and 41 maintain the operating pressures at the inlets of the first and second dryer groups 35 and 38 at a constant level in response to commands from pressure regulators 45 and 46.

The steam supplied to the first and second dryer groups 35 and 38 becomes a drain, and is discharged by Prossl steam to the first and second separators 47 and 48 through exhaust pipes 49 and 50, where the drain and the steam are separated. be done.

Level controllers 57 and 58 are attached to the first and second separators 47 and 48, respectively, and command the control valves 53 and 54 provided in the middle of drain discharge pipes 55 and 56 to discharge a certain amount of drain. Alternatively, the amount is regulated to a lower amount and sent to a boiler room (not shown) by condensate pumps 51 and 52. The steam in the first separator 47 is sent to a condenser (not shown), but the steam in the second separator 48 is sent to the thermocompressor 43 through the steam pipe 61, and this vapor pressure is higher than the operating pressure of the first dryer group 35. If the pressure is also low, the pressure is increased by medium-pressure steam sent from the steam pipe 37 and enters the first dryer group 35 through the supply pipe 36.

On the other hand, control valves 40 (CV-A) and 44 (C-B) provided midway between the supply pipe 36 and the steam pipe 37 are connected to a pressure regulator 4
The control valves 62 (CV1C) and 63 (C-D), which are provided in the middle of the steam pipe 61, are operated by the command from the differential pressure controller 66.
(C-B), a low selector 64 is provided in relation to the pressure regulator 45, and an inverter 67 is provided between this and the differential pressure regulator 66.
By providing a relationship between the control valve 44 and the control valves 62, 63, the control valves 40, 44, 62, 63 as shown in the diagram (valve opening degree and output signal of the controller) in FIG. are all 1
13, and the output signal for the valve opening is, for example, 0.46k9.
As it increases from 1c1t to 0.72k91d, the control valve 4
4 (CV-B) changes from fully closed to fully open, and here control valve 4
0(C-A) starts to open and becomes fully open at 1.0k91cIt.

On the other hand, as the pressure increases from 0.2kgIc71f to 0.46k91c1i, the control valve 63 (CV-D) changes from fully open to fully closed, and at this point the control valve 44 (CV-B) begins to close, and 0.2kgIc71f increases to 0.46k91c1i.
When fully closed at 72kgId, control valve 62 (CV-C)
begins to close and becomes fully closed at 1.0kgId.

Further, the control valve 44 (CV-B) is controlled to the lower of the opening required for the differential pressure in the second dryer group 38 and the opening required for pressure control in the first dryer group 35. Since the present invention is configured as described above in detail, the control valve (C-B) provided in the intermediate pressure steam piping for driving the thermocompressor of the first dryer group is configured to control the differential pressure in the second dryer group. The opening is controlled to the lower of the opening required for the dryer and the opening required for pressure control in the first dryer group, preventing medium-pressure steam from being consumed more than necessary, which increases the cost of paper. can be prevented.

Note that the present invention is effective when applied to paper manufacturing machines.

[Brief explanation of the drawing]

Figure 1 is a diagram of a conventional thermocompressor type cascade system, Figure 2 is a diagram showing the relationship between the valve opening and the output signal of the controller in Figure 1, and Figure 3 is a diagram showing the relationship between the valve opening and the output signal of the controller. A thermocompressor type cascade system diagram showing an embodiment of the present invention, FIG. 4A is a diagram showing the relationship between the valve opening degree and the output signal of the controller in FIG. 3. Explanation of main parts of the figure, 34...Steam pipe for low pressure steam, 35...First dryer group, 36...
・Supply pipe, 37...Steam pipe for medium pressure steam, 38.
...Second dryer group, 39... Supply pipe,
40... Control valve (CV-A), 41...
Control valve (CV), 42...Piping, 43...
・Thermo compressor, 44... control valve (CV-B
), 45...first pressure regulator (pressure regulator),
47...First separator, 48...Second separator, 49,50...Drain discharge pipe, 60,61...Steam pipe, 62... ...Control valve (CV-C), 63...Control valve (CV-D),
64...Low selector, 66...2nd
Differential pressure controller (differential pressure controller), 67... Inverter.

Claims (1)

[Claims] 1 First dryer group connected via a low pressure steam pipe and a control valve (CV-A), also a low pressure steam pipe and a control valve (CV)
A second dryer group is connected through a control valve (CV-B), one steam inlet is connected to a medium pressure steam pipe through a control valve (CV-B), and a steam outlet is connected to a steam supply pipe at the inlet of the first dryer group. a thermocompressor, a first separator connected to the first dryer group via a drain discharge pipe, and a second separator connected to the second dryer group via a drain discharge pipe.
a separator, a steam pipe that connects the other steam supply port of the thermocompressor and the second separator and is provided with a control valve (CV-C) (CV-D) in the middle; an inlet portion of the first dryer group; A pressure regulator is provided in relation to the control valves (CV-A) and (CV-B) to maintain the operating pressure of the second dryer group constant, and ) (CV-D), a low selector is provided between the control valve (CV-B) and the pressure regulator; and the differential pressure regulator of the second dryer group, and further comprising providing an inverter between them.