JP2010133696A - Vapor compression device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor compression device for preventing excessive temperature rise of a compressor and utilizing output of the compressor in maximum as steam energy. <P>SOLUTION: In this vapor compression device 1 including the positive displacement compressor 7 for compressing steam as a vapor-phase object fluid sucked in an active space and discharging the same to a discharge pipe 8 of a prescribed discharge pressure Pd, a liquid introducing means for introducing the liquid-phase object fluid to the active space or a sucking section of the compressor 7, and a drain separator 9 disposed on the discharge pipe 8, and separating a liquid phase component from the object fluid discharged by the compressor 7, the liquid introducing means consumes heat energy remaining after consuming the energy given to the object fluid by the compressor 7 to rise a pressure of the vapor-phase object fluid sucked by the compressor 7 to the discharge pressure, as latent heat in steam for vaporizing the liquid-phase object fluid, and introduces the liquid-phase object fluid of the amount sufficient for discharging a part of the object fluid from the compressor 7 in a state of wet steam of liquid phase. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vapor compression apparatus.

  In the industry, there are many facilities that use steam, but there are very few facilities that can consume the latent heat, and a large amount of steam at 0 MPa and 100 ° C. is discarded. By recovering these discarded low-pressure steam and compressing them with a compressor, there is a steam compressor that regenerates steam at a usable pressure at a lower cost and with less energy than newly evaporating water in a boiler. It has been proposed (for example, Patent Document 1).

  In such a vapor compressor, the discharge pressure of the compressor is also determined by the set pressure of the main steam pipe of the boiler. Although a compressor having a sufficiently large capacity with respect to the amount and pressure of the steam to be compressed is used, excessive output results in excessive temperature rise of the discharged steam. These heats can not only be used effectively, but also increase the temperature of the compressor. In the case of a screw compressor, due to the structure, the service temperature is about 250 ° C., and at most about 300 ° C., so an excessive temperature rise must be avoided.

Japanese Examined Patent Publication No. 6-70540

  In view of the above problems, it is an object of the present invention to provide a vapor compression apparatus that can prevent an excessive increase in temperature of a compressor and can use the output of the compressor as vapor energy to the maximum extent.

  In order to solve the above problems, a vapor compression apparatus according to the present invention includes a positive displacement compressor that compresses vapor that is a gas phase target fluid sucked into a working space and discharges the vapor to a discharge pipe having a predetermined discharge pressure. A liquid introducing means for introducing the target fluid in a liquid phase into the working space of the compressor or a suction portion of the compressor; and a liquid phase from the target fluid discharged from the compressor provided in the discharge pipe. A drain separator that separates a component, and the liquid introducing means boosts the gas phase target fluid sucked by the compressor to the discharge pressure out of the energy that the compressor gives to the target fluid. The remaining thermal energy is consumed as latent heat of vaporization for vaporizing the target fluid in the liquid phase, and the target fluid is discharged from the compressor in the state of wet steam that is partially in the liquid phase. Ten We shall introduce an amount of the subject fluid in the liquid phase.

  According to this configuration, in the compressor, the liquid phase target fluid supplied by the liquid introduction means evaporates, and thus excessive heat is taken away. Therefore, the discharged steam temperature may be higher than the saturated steam temperature at the discharge pressure. Absent. For this reason, the temperature of the compressor does not rise excessively. Further, since the liquid phase target fluid introduced by the liquid introduction means in the compressor is evaporated, the amount of steam to be discharged can be increased from the amount of sucked steam. For this reason, the output energy of the compressor can be converted into the available steam energy. For this reason, the energy efficiency of the whole plant including boiler equipment can be improved.

  Further, in the vapor compression apparatus of the present invention, the liquid introducing means converts the effective output energy of the compressor calculated from the output of the motor driving the compressor per unit amount at the discharge pressure of the target fluid. You may introduce | transduce the said target fluid of a liquid phase much larger than the value remove | divided with the latent heat of vaporization.

  According to this configuration, it is easy to calculate the amount of the target fluid in the liquid phase to be introduced into the working space or the suction portion of the compressor, and the control is simple. Since the sensible heat load of the target fluid is smaller than the latent heat load, the error from the amount of liquid required to make the discharge wet steam is not so large. In addition, since the sensible heat load is ignored, the introduction amount is calculated to be large, and it is a safety-side error in order to keep the discharge in the wet steam.

  In the vapor compression apparatus of the present invention, the target fluid in the liquid phase separated by the drain separator is introduced into the working space or the suction portion, and the target fluid in the insufficient liquid phase is supplied from an external fluid supply source. It may be introduced.

  According to this configuration, the target fluid in the liquid phase separated by the drain separator does not require energy for increasing the temperature in the compressor because the temperature is the saturated steam temperature at the discharge pressure. Increase effect is high.

  Further, in the vapor compression apparatus of the present invention, the liquid introducing means includes a supply valve capable of interrupting the supply of the target fluid from the fluid supply source, and a flow rate detector for detecting a flow rate of the liquid separated by the drain separator. When the detected flow rate of the flow rate detector is a predetermined lower limit flow rate that is higher than the supply amount necessary for the target fluid discharged from the compressor to be saturated steam, the supply valve is opened, The supply valve may be closed when a predetermined upper limit flow rate greater than the lower limit flow rate is reached.

  According to this configuration, when the flow rate of the liquid phase target fluid separated by the drain separator is sufficient to discharge wet steam, no liquid is introduced from another supply source. Since the flow rate of the liquid separated by the drain separator can be measured relatively accurately, it is easy to maintain the discharge of the compressor to be always wet steam.

  According to the present invention, the liquid phase target fluid is introduced into the working space or the suction section so that the discharge of the compressor becomes wet steam, so that the supplied steam is compressed to a predetermined pressure in the output of the compressor. Since the surplus energy generates new steam, the energy can be used effectively, and the compressor temperature does not rise excessively.

It is a block diagram of the plant which has the vapor compression apparatus of 1st Embodiment of this invention. It is a block diagram of the plant which has the vapor compression apparatus of 2nd Embodiment of this invention. It is a block diagram of the plant which has the vapor compression apparatus of 3rd Embodiment of this invention. It is a block diagram of the plant which has the vapor compression apparatus of 4th Embodiment of this invention.

  Embodiments of the present invention will now be described with reference to the drawings. In FIG. 1, the structure of the manufacturing plant containing the vapor compression apparatus 1 of one Embodiment of this invention is shown.

  The vapor compression apparatus 1 is used in a plant that supplies steam (gas target fluid) having a predetermined supply pressure Ph (for example, 0.8 MPaG) from a boiler 2 to a demand facility (manufacturing facility) 3 via a main pipe 4. The high-temperature water separated by the steam trap 5 of the equipment 3 is reduced to a suction pressure Ps (for example, 0.06 MPaG) near the atmospheric pressure by the flash tank 6, and a suction temperature Ts (for example, 110 ° C.), a mass flow rate Gc ( For example, 1000 kg / h) of low-pressure steam is formed between the working space of the screw compressor 7 (a pair of male and female screw rotors that mesh with each other and a casing that accommodates them, and a suction portion and a discharge port of the screw compressor 7. Is discharged to the main pipe 4 via the discharge pipe 8 and discharged to the discharge pressure Pd equal to the supply pressure Ph. It is, as to reduce the generation amount of steam boiler 2, is intended to reduce the eventual fuel consumption of the boiler 2.

  The main pipe 4 is provided with a pressure detecting means for detecting the supply pressure Ph and a temperature detecting means for detecting the temperature Th of the steam at the supply pressure Ph. There are provided pressure detection means for detecting the discharge pressure Pd and temperature detection means for detecting the discharge temperature Td. Signals representing the supply pressure Ph and the discharge pressure Pd detected by each temperature detection means are input to a control means (not shown). The control means appropriately adjusts the rotational speed of the motor 14 that drives the screw compressor 7 so that the discharge pressure Pd becomes equal to the supply pressure Ph.

  In the vapor compression apparatus 1, the discharge pipe 8 is provided with a drain separator 9 that separates water (liquid phase component) from the vapor discharged by the screw compressor 7, and the separated water (liquid phase target fluid) is decompressed. Is introduced into the working space of the screw compressor 7 via the orifice 10 and the flow meter 11. Further, hot water (external fluid supply source) having an atmospheric pressure of 100 ° C. separated from the low-pressure steam by the flash tank 6 is also introduced into the working space of the screw compressor 7 by the pump 12 through the supply valve 13. (Liquid introduction means). The inlet of the hot water separated by the drain separator 9 and the hot water separated by the flash tank 6 to the working space of the screw compressor 7 is located near the suction portion of the screw compressor 7 (the internal pressure is At a position substantially equal to the suction pressure Ph).

  The supply valve 13 is opened when the recirculation flow rate Gr, which is the mass flow rate of water circulated from the discharge pipe 8 of the screw compressor 7 detected by the flow meter 11 to the working space, becomes equal to or less than a predetermined lower limit flow rate Grmin. The When the supply valve 13 is opened, warm water is supplied from the flash tank 6 to the working space of the screw compressor 7 at a replenishment flow rate Gp. The supply valve 13 is closed when the circulating flow rate Gr becomes equal to or higher than a predetermined upper limit flow rate Grmax.

  The lower limit flow rate Grmin is set to a value such that the discharge of the screw compressor 7 continues to become wet steam. That is, the effective output energy (Nc · η) obtained by multiplying the output Nc (for example, 160 kW) of the motor 14 of the screw compressor 7 by the mechanical efficiency η (for example, 95%) of the screw compressor 7 and the suction steam to the discharge pressure Pd. Compared with the difference from the energy for compressing the polytrope, the thermal energy required for vaporizing all the high-temperature water at the flow rate Gr into water vapor at the discharge pressure Pd is sufficiently large, that is, out of the effective output energy. The lower limit flow rate Grmin is set so that the excess is consumed as the latent heat of vaporization of the water and the liquid water remains.

  On the other hand, as the upper limit flow rate Grmax, a value larger than the lower limit flow rate Grmin may be selected to the extent that stability is obtained in terms of control. The replenishment flow rate Gp supplied through the supply valve 13 should not be so large that the screw compressor 7 is in the liquid compression state. When viewed macroscopically, the recirculation flow rate Gr is maintained at a constant flow rate between the lower limit flow rate Grmin and the upper limit flow rate Grmax as long as there is a water amount that can maintain the recirculation flow rate Gr in the system. The flow rate of the steam introduced into the main pipe 4 is a flow rate obtained by adding the average value of the vaporization flow rate Ge to the intake flow rate Gc. The vaporization flow rate Ge is a flow rate of vaporized steam generated in the compression stroke from the intake air of the screw compressor 7.

Briefly, the theoretical vaporization flow rate Gi (for example, 270 kg / kg) obtained by dividing the effective output Nc · η (for example, 152 kW × 3600 = 547200 J / h) of the motor 14 by the latent heat of vaporization (for example, 2030 kJ / kg) at the discharge pressure Pd. h), the lower limit flow rate Grmin can be determined. For example, the lower limit flow rate Grmin may be about 1.1 times the theoretical flow rate, for example. The upper limit flow rate Grmax may be about 1.5 times the theoretical flow rate Gi. The theoretical vaporization flow rate Gi is expressed by the following equation.
Gi = 3600 × Nc · η / rd (unit: kg / h)
However, rd is the latent heat of vaporization at the discharge pressure Pd (unit: kJ / kg).

  Thus, by ensuring the reflux flow rate Gr equal to or higher than the theoretical vaporization flow rate Gi, the screw compressor 7 cannot evaporate all the water introduced into the working space, and the discharged steam is discharged from the discharge pipe 8. At the moment of discharge, the steam becomes wet steam at the saturated steam temperature at the discharge pressure Pd. For this reason, the heat energy added to the steam and water introduced into the screw compressor 7 does not excessively raise the discharge steam or the screw compressor 7 itself beyond the saturated steam temperature of the discharge pressure Pd, resulting in energy loss. Therefore, troubles caused by deformation of the screw compressor 7 due to heat can be prevented.

  In the present embodiment, the amount of steam that can be supplied to the main pipe 4 is obtained by multiplying the average amount of the vaporization flow rate Ge (the instantaneous replenishment flow rate Gp by the opening time ratio of the supply valve 13) from the amount of steam that can be recovered from the demand facility 3. (Flow rate) increases. The average value of the actual vaporization flow rate Ge has a heat load for polytropic compression of the sucked low-pressure steam and a sensible heat load for raising the temperature of the water supplied via the supply valve 13, and therefore, from the theoretical vaporization flow rate Gi. However, the vapor compression apparatus 1 can still pressurize the sucked low-pressure steam and increase the amount by about 20% at maximum.

  When the circulating water having the reflux flow rate Gr is introduced into the working space, the enthalpy is reduced because the circulating water is decompressed from the state pressurized to the discharge pressure Pd to the state of the suction pressure Ps. Then, the recirculation flow rate Gr is added to the difference between the enthalpies (the difference between the enthalpy hd (kJ / kg) of the saturated temperature water under the discharge pressure Pd and the enthalpy hs (kJ / kg) of the saturated temperature water under the suction pressure Ps). Steam with a steam amount Ge1 obtained by dividing the multiplied heat amount Q1 by the vaporization latent heat rs of the steam at the suction pressure Ps is generated as so-called “flash steam”. Then, the steam with the mass flow rate Gc sucked into the working space of the screw compressor 7, the “flash steam” with the steam amount Ge <b> 1, and the water with the water amount (Gr−Ge <b> 1) in the working space flow into the working space. The steam (Gc + Ge1) is compressed, and a part of the heat quantity Q1 of Nc · η is absorbed by the water of the working space water quantity (Gr-Ge1) as the increase in sensible heat. When there is a heat quantity Q2 that cannot be absorbed, vaporized vapor Ge2 is further generated by this heat quantity Q2. And the amount of vapor | steam discharged becomes Gc + Ge1 + Ge2.

Here, when the above relation is arranged, it is expressed by the following formula.
Nc / η = Q1 + Q2
Q1 = Gr × (hd−hs)
Ge1 = Q1 / rs
Ge2 = Q2 / rd
Ge = Ge1 + Ge2

  In this embodiment, the supply valve 13 is controlled based on the output of the motor 14 and the recirculation flow rate Gr. However, since the power consumption of the motor 14 and the flow rate of liquid phase water have high measurement accuracy, the control is reliable. .

  Further, in the vapor compression apparatus 1 of the present embodiment, if the supply valve 13 is a control valve whose opening degree can be adjusted, if water is always supplied from the flash tank 6 via the supply valve 13, circulation is possible. Even if the flow rate Gr is smaller than the average value of the replenishment flow rate Gp or the theoretical flow rate Gi, if the total amount of water injected into the working space exceeds the theoretical vaporization flow rate Gi, the discharge steam of the screw compressor 7 is reduced. It is possible to maintain a wet steam.

  Further, in the vapor compression apparatus 1 of the present embodiment, the supply valve 13 may be controlled according to the discharge temperature Td of the discharge pipe 8 without depending on the flow meter 11. If the amount of water supplied to the working space of the screw compressor 7 is too small, the discharge steam of the screw compressor 7 becomes dry steam, and the saturated evaporation temperature at the discharge pressure Pd is caused by the energy supplied excessively by the screw compressor. Heated to a higher temperature. For this reason, in the discharge pipe 8, the temperature of the steam discharged by the screw compressor 7 is detected, and when the steam temperature reaches a predetermined set temperature, it is determined that the steam is dry steam (heated steam). The supply valve 13 may be opened for a predetermined time such that the circulation flow rate Gr becomes sufficiently large.

  Furthermore, in FIG. 2, the structure of the manufacturing plant containing the vapor compression apparatus 1a of 2nd Embodiment of this invention is shown. In addition, regarding the following embodiment, the same code | symbol is attached | subjected to the same component as embodiment demonstrated previously, and the overlapping description is abbreviate | omitted.

  In the vapor compression apparatus 1a of the present embodiment, circulating water having a circulating flow rate Gr separated by a drain separator 9 and supplied via an orifice 10 and a flow meter 11 and separated from low-pressure steam by a flash tank 6 and pumps 12 and The hot water supplied through the supply valve 13 and having the replenishment flow rate Gp is combined and introduced into the suction portion of the screw compressor 7.

  As shown in the present embodiment, according to the present invention, the circulating water having the circulating flow rate Gr is not introduced into the working space of the screw compressor 7 as in the vapor compressor 1a of the first embodiment, but the screw compressor. You may comprise so that it may introduce into 7 suction parts.

  Moreover, in FIG. 3, the structure of the manufacturing plant containing the vapor compression apparatus 1b of 3rd Embodiment of this invention is shown. In the vapor compression apparatus 1b of the present embodiment, liquid-phase water separated by the drain separator 9 is introduced into the working space of the screw compressor 7 as circulating water having a recirculation flow rate Gr and separated from low-pressure steam by the flash tank 6. Hot water with a replenishment flow rate Gp is introduced into the suction portion of the screw compressor 7.

  More specifically, the circulating water is supplied to the middle portion of the working space of the screw compressor 7 and a position close to the discharge port, and the pressure at the supply destination is different. Therefore, in order to optimize the amount of water, 10 are individually provided in the branch paths connected to the respective working spaces.

  If the hot water of the replenishment flow rate Gp separated in the flash tank 6 is lower in temperature than the low-pressure steam separated in the flash tank 6 due to heat loss of the piping, the low-pressure steam in the suction portion of the screw compressor 7 In that case, it is preferable to mix and supply with a part of the high-temperature circulating water separated by the drain separator 9.

  Further, according to the present invention, as in the vapor compression apparatus 1c of the fourth embodiment shown in FIG. 4, the liquid phase water separated by the drain separator 9 is used as circulating water of the recirculation flow rate Gr, and the middle stage of the screw compressor 7 and The hot water having the replenishment flow rate Gp introduced into the downstream working space and separated from the low pressure steam by the flash tank 6 may be introduced into the low pressure working space close to the suction portion.

  In addition, regarding the above-described vapor compression apparatuses 1, 1a, 1b, and 1c, the control for appropriately adjusting the rotation speed of the motor 14 that drives the screw compressor 7 so as to make the discharge pressure Pd equal to the supply pressure Ph has been described. However, a plant in which the amount of steam supplied from the boiler 2 is large and the supply pressure Ph of the main pipe 4 and thus the discharge pressure Pd of the screw compressor 7 is kept constant regardless of the operating state of the steam compressor 1. Then, you may control the rotation speed of the screw compressor 7 so that the suction pressure Ps, ie, the pressure of the flash tank 6, may be kept constant.

  Although the above embodiment demonstrated vapor compression apparatus 1,1a, 1b, 1c which compresses water vapor | steam, this invention is a vapor compression apparatus which compresses the vapor | steam of other types of object fluids, such as a natural gas compression apparatus. It can also be applied to.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c ... Steam compression apparatus 2 ... Boiler 3 ... Demand equipment 4 ... Main piping 5 ... Steam trap 6 ... Flash tank 7 ... Screw compressor 8 ... Discharge piping 9 ... Drain separator 10 ... Orifice 11 ... Flow meter 12 ... Pump 13 ... Supply valve 14 ... Motor

Claims (4)

A positive displacement compressor that compresses vapor, which is a target fluid in a gas phase, sucked into the working space, and discharges the vapor into a discharge pipe having a predetermined discharge pressure;
A liquid introducing means for introducing the target fluid in a liquid phase into the working space of the compressor or a suction portion of the compressor;
A drain separator that is provided in the discharge pipe and separates a liquid phase from the target fluid discharged by the compressor;
The liquid introduction means uses the thermal energy remaining in the liquid to be consumed because the gas-phase target fluid sucked by the compressor is boosted to the discharge pressure among the energy given to the target fluid by the compressor. A target of the liquid phase in an amount sufficient to be consumed as latent heat of vaporization for vaporizing the target fluid of the phase, and to discharge the target fluid from the compressor in the state of wet steam partially in the liquid phase A vapor compression apparatus characterized by introducing a fluid.   The liquid introducing means has a larger amount than the value obtained by dividing the effective output energy of the compressor calculated from the output of the motor driving the compressor by the latent heat of vaporization per unit amount at the discharge pressure of the target fluid. The vapor compression apparatus according to claim 1, wherein the target fluid in a liquid phase is introduced.   The liquid introduction means introduces the target fluid in the liquid phase separated by the drain separator into the working space or the suction portion, and introduces the target fluid in the insufficient liquid phase from an external fluid supply source. The vapor compression apparatus according to claim 1 or 2, characterized in that   The liquid introduction means includes a supply valve capable of interrupting the supply of the target fluid from the fluid supply source, and a flow rate detector for detecting a flow rate of the liquid separated by the drain separator, and the detection of the flow rate detector When the flow rate becomes a predetermined lower limit flow rate that is equal to or higher than the supply amount necessary for the target fluid discharged from the compressor to become saturated steam, the supply valve is opened and becomes a predetermined upper limit flow rate that is larger than the lower limit flow rate. The vapor compression apparatus according to claim 3, wherein the supply valve is closed.

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