KR101342792B1 - Water injection type vapor compressor - Google Patents

Abstract

An object of the present invention is to provide a configuration capable of accurately grasping the temperature of the replenishing water and the state amount of the intake steam, thereby preventing the discharge steam from becoming superheated steam and preventing the amount of discharge steam from decreasing. It is to provide a steam compressor.
An intake side drain separator 9 provided in the intake pipe 6, a spray water pump 4 for injecting feed water into the compression space inside the screw compressor 2, and a water supply thermometer for detecting the temperature of the feed water ( 18) and a water injection type steam compressor 1 having a control unit 5 for controlling the injection amount of the replenishment water. The control part 5 is based on the specific enthalpy of the intake steam which flows in the intake pipe 6 downstream from the intake side drain separator 9, and the specific enthalpy of the replenishment water calculated | required by the detected value of the water supply thermometer 18, The injection amount of the replenishing water is controlled so that the output energy of the screw compressor 2 remaining in order to boost the suction steam to a predetermined discharge pressure and the amount of vaporization heat of the replenishing water become equal.

Description

Water Jet Steam Compressor {WATER INJECTION TYPE VAPOR COMPRESSOR}

The present invention relates to a water jet steam compressor having water supply means for injecting water into at least one of a compression space inside the compressor and an intake pipe connected to the compressor.

As a technique for controlling the amount of water jet in the water jet steam compressor, there is a technique described in Patent Document 1, for example. The control technique described in Patent Literature 1 consumes the heat energy remaining to boost the steam sucked by the compressor to its discharge pressure among the energy imparted to the steam as the latent heat of evaporation to vaporize the introduced water (supplemented water). In addition, it is said that the amount of introduced water (supply water) is sufficient to discharge steam in the state of wet steam, which is partially liquid from the compressor. As the make-up water injected into the compressor evaporates, it can be expected to generate steam equal to or larger than the amount of steam sucked by the compressor. That is, it can be expected to effectively use the energy output excessively from a compressor.

Japanese Patent Application Publication No. 2010-133696

However, in the control of the water injection amount described in Patent Literature 1, the steam discharged from the compressor may become superheated steam, and it is not sufficient as a control to use the energy excessively output from the compressor. Since the control described in Patent Literature 1 is not performed by grasping the temperature of the introduced water (supply water), when the temperature of the replenishing water becomes high, the amount of vaporization heat of the replenishing water is overestimated. The discharge steam becomes insufficient and becomes superheated steam.

On the other hand, if the amount of replenishment water injected into the compressor is too large, part of the steam sucked by the compressor by the excess replenishing water condenses and the amount of discharged vapor is reduced. For this reason, it is ideal to control the amount of the replenishment water so that the energy output excessively from the compressor and the amount of heat of vaporization of the replenishment water become equal. In order to grasp excess energy output from a compressor, it is necessary to grasp | ascertain the quantity of state of the steam (steam before compression) which the compressor inhales. Here, the steam sucked by the compressor is often wet steam. In patent document 1, although the thermometer and the pressure gauge are provided in the intake pipe of a compressor, it is difficult to grasp the state quantity (specific enthalpy) of wet steam only by a thermometer and a pressure gauge.

The present invention has been made in view of the above circumstances, and its object is to provide a configuration capable of accurately grasping the temperature of the make-up water and the state amount of the intake steam, thereby preventing the discharge steam from becoming superheated steam and increasing the amount of discharge steam. It is to provide a water jet steam compressor that can prevent the reduction.

The present invention relates to a volumetric compressor for compressing and discharging steam, an intake pipe and a discharge pipe connected to the compressor, through which steam flows, an intake side drain separating means provided in the intake pipe, a compression space inside the compressor, Water supply means for injecting replenishment water to at least one of the intake pipes downstream of the intake side drain separating means, a control unit for controlling the injection amount of the replenishment water injected by the water supply means, and injection by the water supply means And a water supply thermometer for detecting a temperature of the replenishment water to be supplied, wherein the control unit is downstream of the intake side drain separation means and detects specific enthalpy of intake steam flowing through the intake pipe before the replenishment water is injected and supplied, and detection of the water supply thermometer. Based on the specific enthalpy of the make-up water determined by the value, the suction steam is boosted to a predetermined discharge pressure. A water injection steam compressor is characterized in that the injection amount of the replenishment water is controlled so that the output energy of the compressor left to consume and the amount of vaporization heat of the replenishment water become equal.

A water supply thermometer can grasp | ascertain the temperature of supplementary water, and also the quantity (specific enthalpy) of the supplementary water. In addition, when the suction steam is wet steam, water (liquid content) in the suction steam is removed by the intake side drain separating means, and the suction steam is saturated dry steam. The state quantity (specific enthalpy) of saturated dry steam can be grasped | ascertained from the pressure value (or temperature value). That is, according to the configuration of the present invention described above, it is possible to accurately grasp the temperature of the replenishment water and the state quantity of the intake steam, and by controlling the injection quantity of the replenishment water based on these, it is possible to prevent the discharge steam from becoming superheated steam and to discharge it. The amount of steam can be prevented from decreasing.

Further, in the present invention, there is further provided a discharge side drain separating means provided in the discharge tube, wherein the control unit includes a specific enthalpy of discharge steam flowing through the discharge tube downstream from the discharge side drain separating means, the compressor and the discharge side. It is preferable to control the injection amount of the make-up water so that the difference in specific enthalpy of the discharge steam flowing through the discharge pipe between the drain separating means becomes smaller.

According to this configuration, it is possible to further prevent the discharge steam from becoming superheated steam and to prevent the amount of the discharge steam from decreasing.

According to the present invention, by installing the above water supply thermometer and the intake side drain separating means in the water injection type steam compressor, it is possible to accurately grasp the temperature of the make-up water and the state quantity (specific enthalpy) of the intake steam, and based on these, the injection amount of the make-up water. By controlling this, it is possible to provide a water jet steam compressor which can prevent the discharge steam from becoming superheated steam and also prevent the amount of discharge steam from decreasing.

1 is a block diagram showing a water jet steam compressor according to one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Configuration of Water Jet Steam Compressor)

As shown in FIG. 1, the water jet steam compressor 1 includes a screw compressor 2 for compressing and discharging steam, an electric motor 3 for driving the screw compressor 2, a jet water pump 4, and jet water. The control part 5 which controls the pump 4 is comprised. The injection water pump 4 is driven by the electric motor 4a, and the electric motor 4a is rotationally controlled by the inverter 4b. The injection water pump 4 is corresponded to the water supply means in this invention. Instead of the screw compressor, a volumetric compressor such as rotary, scroll, or route may be used.

An intake pipe 6 and a discharge pipe 7 are connected to the screw compressor 2. The intake pipe 6 is a path for supplying the compression target steam to the screw compressor 2, and the discharge pipe 7 is a path for sending the vapor after compression. For example, steam of about 0.1 MPa and about 100 ° C. is compressed by the screw compressor 2 to 0.8 MPa saturated steam and discharged. In addition, water vapor generated by boiling the hot water at about 60 ° C. under reduced pressure may be compressed by a screw compressor 2 (water jet steam compressor 1).

The intake pipe 6 is provided with an intake side drain separator 9. In the intake pipe 6 between the intake side drain separator 9 and the screw compressor 2, the intake steam pressure gauge 10, the intake steam thermometer 11, and the intake steam flow meter 12 are sequentially provided from the upstream side. It is installed. If a large amount of liquid (drain) enters the screw compressor 2, erosion may occur. By providing the intake side drain separator 9 in the intake pipe 6, the inflow of liquid (drain) from the intake side can be prevented.

The discharge side drain separator 15 is provided in the discharge tube 7. In addition, a first discharge steam thermometer 13 and a first discharge steam pressure gauge 14 are provided in the discharge tube 7 between the screw compressor 2 and the discharge side drain separator 15 in order from the upstream side. The discharge pipe 7 downstream from the separator 15 is provided with the 2nd discharge steam pressure gauge 16 and the 2nd discharge steam thermometer 17 in order from an upstream.

In addition, a water supply pipe 8 is connected to the screw compressor 2. The water supply pipe 8 is provided with the injection water pump 4. The feed water flow meter 19 is installed in the water supply pipe 8 between the injection water pump 4 and the screw compressor 2, and the water supply thermometer 18 is provided in the water supply pipe 8 upstream of the injection water pump 4. It is installed. Moreover, the water supply thermometer 18 may be provided in the water supply pipe 8 of the downstream side rather than the injection water pump 4. In addition, since the temperature of the replenishment water can be detected by the water supply thermometer 18, the water supply thermometer 18 does not necessarily need to be provided in the water supply pipe 8.

In the present embodiment, the make-up water is injected and supplied only into the compression space of the screw compressor 2, but is not necessarily limited to this embodiment. For example, it may be downstream from the intake side drain separator 9 and may supply and supply replenishment water into the intake pipe 6 between the intake steam flowmeter 12 and the screw compressor 2. In this case, the tip of the water supply pipe 8 is connected to the intake pipe 6 between the intake steam flowmeter 12 and the screw compressor 2. That is, using the injection water pump 4, the intake pipe of the compression space of the screw compressor 2 and the intake pipe downstream of the intake side drain separator 9 (also downstream of instruments such as a pressure gauge, a thermometer and a flow meter) ( 6) At least one of the supplementary water is injected into and supplied. In addition, the compression space of the screw compressor 2 means the space between the pair of male screw rotors which mesh with each other, and the casing which accommodates a screw rotor. In addition, the replenishment water may be hot water or water at room temperature. For example, condensate with condensate from the outlet steam of the plant is used as make-up water.

The control part 5 is for controlling the injection amount of the make-up water injected by the injection water pump 4 to the compression space of the screw compressor 2. In this embodiment, the suction steam pressure gauge 10, the suction steam thermometer 11, the suction steam flowmeter 12, the first discharge steam thermometer 13, the first discharge steam pressure gauge 14, the second discharge steam pressure gauge ( 16), each measured value signal from the 2nd discharge steam thermometer 17, the water supply thermometer 18, and the feedwater flowmeter 19, and the rotation speed signal of the electric motor 3 are input into the control part 5. As shown in FIG. Moreover, the signal from the control part 5 is input to the inverter 4b, and the rotation speed (discharge amount) of the injection water pump 4 is controlled.

(Control of water injection amount)

Next, the injection amount control of the replenishment water by the control part 5 is demonstrated.

First, the premise of this invention is described. The screw compressor 2 (and the electric motor 3) is used having a sufficiently large capacity (output) with respect to the amount and pressure of steam to compress, but the excess output makes the discharge steam superheated steam. Patent Document 1 (Japanese Patent Application Laid-open No. 2010-133696) described above describes a technique for controlling the injection amount of the make-up water injected into the compression space of the screw compressor 2 or the like so that the discharge steam does not become superheated steam. have. However, the control technique described in Patent Document 1 has not yet been sufficient as described in the column of "Problems to Solve Invention". Hereinafter, the injection amount control of this embodiment which concerns on this invention is described.

Calculation of the injection amount Gp (for example, unit: kg / h) of replenishment water performed by the control part 5 is performed by following Formula.

Lg: Steam compression power of the screw compressor (kJ / h)

Qs: The amount of work (kJ / h) that compresses the suction steam to saturated dry steam at the discharge pressure

QL: The remaining output energy (kJ / h) consumed to boost the suction steam to the discharge pressure

HL: Heat quantity (kJ / kg) necessary to make 1 kg of supply water into saturated dry steam at discharge pressure

(How to get Lg)

The steam compression power Lg of the screw compressor 2 includes intake pressure (detected value Ps of intake steam pressure gauge 10), discharge pressure (detected value Pd of first discharge steam pressure gauge 14), screw It is calculated in the control part 5 by the internal volume ratio of the compressor 2, the theoretical intake volume of the screw compressor 2, etc. In addition, the theoretical intake volume of the screw compressor 2 is multiplied by the volume the screw compressor 2 sucks per revolution, multiplied by the rotational speed of the screw compressor 2 (obtained from the rotational signal of the motor 3). Is calculated.

In addition, the steam compression power Lg may be calculated by multiplying the power consumption of the screw compressor 2 (motor 3) by a constant efficiency, and the steam is based on the current value of the screw compressor 2 (motor 3). The compression power Lg may be calculated.

(How to get Qs)

The amount Qs of compressing the suction steam to the saturated dry steam at the discharge pressure is the specific enthalpy hd0 (kJ / kg) of the saturated dry steam at a predetermined discharge pressure (for example, 0.8 MPa) and the suction steam. It is calculated by multiplying the difference in specific enthalpy hs (kJ / kg) by the mass flow rate Gc (kg / h) of the intake steam.

[Method of obtaining specific enthalpy (hs)]

First, since the intake side drain separator 9 is provided in the intake pipe 6, when the intake vapor to be compressed is wet steam, the water (liquid content) in the intake vapor is passed through the intake side drain separator 9. The suction vapor is removed to become saturated dry steam. Almost no saturated (saturation 100) saturated dry steam, but almost saturated dry steam. In addition, when the suction steam to be compressed is superheated steam, superheated steam remains as it is. In other words, the suction steam passing through the intake side drain separator 9 becomes saturated dry steam or superheated steam.

The control part 5 calculates the specific enthalpy hs of the suction steam which is compression object based on the detection value Ps of the suction steam pressure gauge 10, and the detection value Ts of the suction steam thermometer 11. As shown in FIG. In addition, when the inhalation vapor is saturated dry steam, the control part 5 is based on the detection value Ps of the intake steam pressure gauge 10 or the detection value Ts of the intake steam thermometer 11, and The peeling (hs) (kJ / kg) is obtained. In this way, by providing the intake side drain separator 9 in the intake pipe 6, the suction steam to be compressed becomes saturated dry steam or superheated steam, and the suction steam pressure gauge 10 and the suction steam thermometer 11. The amount of state (specific enthalpy) can be accurately determined based on the signal from.

In addition, the mass flow rate Gc of the suction steam is calculated from the rotation speed of the screw compressor 2. In addition, you may calculate Gc from the detection value of the suction steam flowmeter 12. FIG. The density of the intake steam is calculated based on the signals from the intake steam pressure gauge 10 and the intake steam thermometer 11.

(How to get HL)

The amount of heat HL required to make 1 kg of make-up water into saturated dry steam at the discharge pressure is equal to the specific enthalpy hd0 (kJ / kg) of the saturated dry steam at a predetermined discharge pressure (for example, 0.8 MPa). It is the difference of specific enthalpy (hL) (kJ / kg) of make-up water. The control part 5 calculates specific enthalpy hL of replenishment water based on the detection value TL of the water supply thermometer 18. FIG. In this way, the water supply thermometer 18 can grasp the state quantity (specific enthalpy) of the replenishment water.

In this way, the control part 5 controls the injection quantity Gp of replenishment water so that the output energy QL of the screw compressor 2 which was consumed in order to raise | suck a suction steam to predetermined | prescribed discharge pressure, and the amount of vaporization heat of replenishment water become equal. ) Is calculated. And the control part 5 gives a signal so that it may become injection amount Gp with respect to the injection water pump 4. The injection quantity from the injection water pump 4 is monitored by the replenishment water flow meter 19, and controls the rotation speed of the injection water pump 4 so that it may become injection amount Gp.

According to the water injection quantity control of this embodiment, the control part 5 can grasp | ascertain the temperature of replenishment water and the state quantity of suction steam. By controlling the injection amount of the replenishing water based on these, it is possible to prevent the discharge steam from becoming superheated steam and to prevent the amount of discharge steam from decreasing. In other words, the energy remaining after compressing the supplied steam to a predetermined pressure during the output of the compressor can generate new steam from the replenishment water as much as possible without reducing the sucked steam, so that the energy can be effectively used. The temperature does not rise excessively.

Here, by the control part 5, the specific enthalpy hdH (kJ / kg) of the discharge steam which flows through the discharge pipe 7 downstream from the discharge side drain separator 15, and upstream than the discharge side drain separator 15 here It is preferable to further control the injection amount of the replenishment water so that the difference in the specific enthalpy hdL (kJ / kg) of the discharge steam flowing through the discharge pipe 7 of the nozzle becomes small. There is also a relationship of specific enthalpy (hdH)> specific enthalpy (hdL). When the difference between the specific enthalpy hdH and the specific enthalpy hdL increases to a predetermined threshold value, the amount of injection is reduced by controlling the rotation speed of the injection water pump 4 in a direction of decreasing. Thereby, it changes in the direction from which the difference of specific enthalpy hdH and specific enthalpy hdL becomes small, and discharge steam becomes close to saturated dry steam. In addition, when the difference between the specific enthalpy hdH and the specific enthalpy hdL decreases to a predetermined threshold value, the rotation speed of the injection water pump 4 is returned to the control which makes the injection amount Gp.

The specific enthalpy hdL (kJ / kg) of the discharge steam upstream from the discharge side drain separator 15 is determined by the detected value Td of the first discharge steam thermometer 13 and / or the first discharge steam pressure gauge 14. The specific enthalpy hdH of the discharge steam downstream from the discharge side drain separator 15 is determined by the control unit 5 based on the detected value Pd, and the detected value Ph of the second discharge steam pressure gauge 16 and And / or the control unit 5 is obtained based on the detected value Th of the second discharge steam thermometer 17.

In the specific enthalpy hdL (kJ / kg), the discharge steam on the upstream side of the discharge side drain separator 15 is obtained as saturated dry steam or superheated steam. On the other hand, the discharge steam downstream from the discharge side drain separator 15 passes through the discharge side drain separator 15 to become saturated dry steam or superheated steam.

When the intake pressure, discharge pressure, etc. of the screw compressor 2 change, the injection amount Gp also changes. When the amount of replenishing water is vaporized to Ge (kg / h), the amount of drainage from the discharge-side drain separator 15 is Gp-Ge. Although it is preferable to grasp | ascertain this drain amount Gp-Ge correctly, it is difficult to measure Gp-Ge. Therefore, instead of making the injection amount control based on the drain amount Gp-Ge, it is set as the injection amount control based on the difference of specific enthalpy hdH and specific enthalpy hdL. According to this injection amount control, the discharge steam can be made closer to the saturated dry steam, and as a result, it is possible to prevent the discharge steam from becoming more superheated steam and to prevent the amount of discharge steam from decreasing.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, It can change and implement variously in the range as described in a claim.

1: water jet steam compressor
2: screw compressor
3: electric motor
4: injection water pump (water supply means)
5:
6: intake pipe
7: Discharge tube
8: water supply pipe
9: intake side drain separator (intake side drain separating means)
15: discharge side drain separator (discharge side drain separating means)
18: water supply thermometer

Claims (2)

A volumetric compressor that compresses and discharges steam;
An intake pipe and a discharge pipe connected to the compressor and in which steam flows;
An intake steam pressure gauge, an intake steam thermometer, and an intake side drain separating means installed in the intake pipe;
Water supply means for injecting replenishment water into at least one of the compression space inside the compressor and the intake pipe downstream of the intake side drain separating means;
A control unit for controlling the injection amount of the replenishment water injected by the water supply means;
A water supply thermometer for detecting the temperature of the replenishment water injected by the water supply means,
The control unit is a specific enthalpy (hs) of the suction steam flowing through the intake pipe downstream of the intake side drain separating means, which is determined by the detection values of the suction steam pressure gauge and the suction steam thermometer, and before the replenishment water is injected and supplied. Based on the specific enthalpy hL of the make-up water determined by the detection value of the water supply thermometer, the heat energy QL and the heat of vaporization of the make-up water, which are consumed to boost the suction steam to a predetermined discharge pressure, remain. The water injection type steam compressor characterized by controlling the injection amount (Gp) of the make-up water so that (HL) becomes equal. The discharge side drain separating means provided in the discharge pipe,
The control unit is configured such that the difference between the specific enthalpy of the discharge steam flowing through the discharge pipe on the downstream side and the specific enthalpy of the discharge steam flowing through the discharge pipe between the compressor and the discharge side drain separating means is smaller than the discharge side drain separating means. Water injection steam compressor, characterized in that for controlling the injection amount of the replenishment water.

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