JP5593906B2 - Heat pump steam generator - Google Patents

Description

  The present invention relates to a heat pump type steam generator that recovers exhaust heat from factory wastewater and generates steam.

As one of the steam generators, there is a heat pump steam generator using a heat pump. The heat pump steam generator recovers waste heat such as factory wastewater to generate steam, and has the advantages of lower running costs and reduced CO ₂ emissions compared to combustion steam generators. There is.

  In Patent Document 1, the other end of the refrigerant pipe having one end connected to the discharge side of the compressor is connected to the compressor via a steam generating heat exchanger, a hot water generating heat exchanger, an expansion valve, and a heat recovery unit. The refrigerant circuit connected to the suction side of the heat recovery unit recovers heat from the external heat source in the heat recovery unit, generates steam in the heat generation heat exchanger, and generates hot water in the heat generation heat exchanger A configured heat pump steam / hot water generator is disclosed. And in the heat pump steam / hot water generator of Patent Document 1, water contained in the steam generated by the steam generating heat exchanger or liquefied by the condensation of steam is separated by the gas / liquid separator for water supply, It is taken out from the vapor supply pipe provided in the gas phase of the gas-liquid separator.

JP 2007-232357 A (Claim 1, paragraph number 0023)

  In the heat pump steam / hot water generator disclosed in the cited document 1, the output system from the gas / liquid separator for feed water is only the steam supply pipe, so the amount of supply water is adjusted according to the amount of steam taken out. Therefore, it is considered that the water level in the gas-liquid separator for feed water is stabilized. For this reason, it is necessary to stop the supply of supply water when steam is not taken out. When the supply water is not supplied, the flow of thermal energy from the refrigerant circuit (corresponding to the heat pump circulation path of the present invention) is almost lost, so that devices such as a compressor may be overheated and damaged. For this reason, when stopping the extraction of steam, it was necessary to stop the operation of the entire apparatus.

  However, once the apparatus is completely stopped, it takes time to stabilize the apparatus, and it is difficult to supply steam promptly according to demand.

  Therefore, an object of the present invention is to provide a heat pump type steam generator capable of standby operation and capable of supplying a required amount of steam quickly according to demand when supplying steam to the outside again. It is in.

In order to achieve the above object, the heat pump type steam generator of the present invention comprises:
An exhaust heat recovery unit that recovers heat from an external heat source and heats the medium, a compressor that compresses the medium that has passed through the exhaust heat recovery unit, and transfers the heat of the medium compressed by the compressor to supply water A heat pump circulation path having a medium condenser that generates a gas-liquid two-phase flow of hot water and steam, and an expander that depressurizes and lowers the temperature of the medium that has passed through the medium condenser;
A water supply path for introducing the supply water into the medium condenser;
A gas-liquid separator that separates the gas-liquid two-phase flow of hot water and steam generated by the medium condenser into water vapor and water;
A vapor extraction path provided in a gas phase portion of the gas-liquid separator;
A heat pump type steam generator comprising a water circulation path connecting the liquid phase part of the gas-liquid separator and the water supply path,
Water supply amount adjusting means disposed in the water supply path;
A drainage path provided in the liquid phase part of the gas-liquid separator;
A drainage valve interposed in the drainage path,
When the amount of steam from the steam extraction path is reduced or stopped, the operation of the compressor is lowered to a preset minimum level, the drain valve is opened, and the standby operation for continuing the operation of the heat pump is performed. It is controlled.

Heat pump vapor generating apparatus of the present invention, the water supply path arranged supplied water volume adjustment means, the flow rate is equal to the sum of the flow rate of waste water discharged from the flow and the discharge water path of the steam withdrawn from the steam extraction route It is preferable that the supply water is controlled to be supplied.

  The heat pump type steam generator according to the present invention further includes a pressure gauge for detecting the pressure in the gas-liquid separator, and the drain valve opens the detected value of the pressure gauge at a set value or more, and the pressure gauge It is preferable that the detection value is controlled so as to close when the value is equal to or less than the set value.

  The heat pump steam generating apparatus of the present invention can perform standby operation without stopping the entire apparatus even when the extraction of steam is stopped or reduced. For this reason, even if the demand for steam increases again, it is possible to respond quickly to the demand.

It is a schematic block diagram of the heat pump type | formula steam generator of this invention. It is a control block diagram of the heat pump type steam generator of the present invention.

FIG. 1 is a schematic view of a heat pump type steam generator of the present invention.
As shown in FIG. 1, in this heat pump type steam generator, a pipe L <b> 1 extending from the outlet side of the first exhaust heat recovery unit 1 includes a compressor 2, a medium condenser 3, a medium cooler 4, and an expander 5. A heat pump circulation path 20 connected to the entrance side of the first exhaust heat recovery device 1 is provided in order.

  In the heat pump circulation path 20, a medium (hereinafter referred to as a heat pump medium) circulates and circulates, and a heat medium (in this embodiment, waste water is used as a heat medium sent from an external heat source via the heat pump medium. The heat of the heat pump medium is transferred to the supply water sent from the water supply source to generate steam.

  As the heat pump medium, a medium having a high critical temperature, a low global warming potential, and a low ozone depletion potential is preferably used. As such a medium, R245fa, a hydrofluoroether medium, pentane which is a natural medium, or the like can be preferably used.

  A pipe L2 extending from the external heat source and through which the exhaust hot water flows is connected to the outside of the system through the first exhaust heat recovery device 1 and the second exhaust heat recovery device 6 in this order.

  The pipe L3 extending from the water supply source and through which the supply water flows passes through the water supply pump P1, the second exhaust heat recovery device 6, the medium cooler 4, and the medium condenser 3 in this order, and the gas phase of the gas-liquid separator 7 Connected to the department.

  The gas-liquid separator 7 is provided with a steam extraction pipe L4 with a steam flow meter 31 interposed in the gas phase portion. Further, a pipe L5 provided with an on-off valve V1 extending to a drainage system outside the system and a pipe L6 connected to a pipe L3a between the medium cooler 4 and the medium condenser 3 are provided in the liquid phase part. Yes. The gas-liquid separator 7 is provided with a pressure gauge 32 for detecting the pressure in the gas phase portion and a water level gauge 33 for detecting the water level of the stored hot water.

  A liquid feed pump P2 is disposed on the downstream side of the connection portion between the pipe L3a and the pipe L6.

  Next, the operation at the time of steady operation of the heat pump steam generator of the present invention will be described along the flow of heat with reference to the control block diagram of FIG.

(Waste water)
Waste heat water sent from an external heat source such as a factory waste water system flows through the pipe L2, passes through the first waste heat recovery device 1 and the second waste heat recovery device 6 in this order, and is sent out of the system.
In the 1st waste heat recovery device 1, the heat of waste water is transmitted to the heat pump medium which distribute | circulates the piping L1, and a heat pump medium is heated.
In the second exhaust heat recovery device 6, the remaining heat of the exhaust water after heating the heat pump medium is transferred to the supply water flowing through the pipe L <b> 3 to primarily heat the supply water.

(Heat pump medium)
The heat pump medium heated in the first exhaust heat recovery device 1 by heat exchange with the exhaust hot water is compressed to a predetermined pressure by the compressor 2 to obtain a high-temperature and high-pressure medium. This high-temperature and high-pressure medium passes through the medium condenser 3 and the medium cooler 4 in this order, and is used for heat exchange with the supply water flowing through the pipe L3.

  As shown in the control block diagram of FIG. 2, the compressor 2 uses the compressor controller 41 to measure the pressure gauge 32 of the gas-liquid separator 7 and the pressure setting value of the gas-liquid separator 7 (in this embodiment, 200 kPa · abs (corresponding to a temperature of 120 ° C.) is controlled based on the rotational speed command value that is output after being compensated for. When the measured value of the pressure gauge 32 is smaller than the pressure set value of the gas-liquid separator 7, the rotational speed is increased, and when the measured value of the pressure gauge 32 is larger than the pressure set value of the gas-liquid separator 7, the rotational speed is decreased. Control is performed. The upper and lower limits of the rotational speed of the compressor 2 are controlled by the upper and lower limiter 42. When a command signal of the rotational speed exceeding the upper limit is output from the compressor controller 41, the rotational speed at the preset upper limit is compressed. When a command signal with a rotational speed lower than the lower limit is output to the machine 2, the lower limit rotational speed set in advance is output to the compressor 2.

  In the medium condenser 3, the heat of the high-temperature and high-pressure medium (heat pump medium) is supplied to the heated water (secondary preheated supply water described later) and the gas-liquid separator 7 sent from the pipe L6. Heat and water (mixed water with the warm water inside) to generate a gas-liquid two-phase flow of warm water and steam.

  In the medium cooler 4, the residual heat of the heat pump medium after passing through the first medium condenser 3 is transferred to the supply water passing through the pipe L <b> 3, which has been preliminarily heated by heat exchange with the above-described exhaust hot water, so as to be a secondary reserve. Heat.

  The heat pump medium that has passed through the medium cooler 4 is expanded to a predetermined pressure by the expander 5 to lower the temperature, and is reintroduced into the first exhaust heat recovery device 1 to recover heat from the exhaust hot water flowing through the pipe L2. Used.

(Supply water)
In the supply water supplied from the water supply source by the water supply pump P1, the mass flow rate Q1 of the supply water is the total amount (Q2 + Q3) of the mass flow rate Q2 of the steam taken out from the pipe L4 and the drainage flow rate Q3 from the pipe L5. To be controlled. Specifically, as shown in the control block diagram of FIG. 2, first, based on the measured value of the pressure gauge 32 of the gas-liquid separator 7 and the valve capacity coefficient of the on-off valve V1, the flow rate of drainage (blow-off) from the pipe L5. (Down flow rate) The calculated value is output by the blow down flow rate calculator 43. Further, the steam flow rate measurement value is output by the steam flow meter 31 provided in the pipe L4. Further, the measurement value of the water level gauge 33 of the gas-liquid separator 7 and the water level setting value of the gas-liquid separator 7 are input to the water level compensator 44, and the flow rate correction value is output. Then, the sum of the blowdown flow rate calculation value, the steam flow rate measurement value, and the flow rate correction value is input to the flow rate controllers 45 and 46 as a flow rate command value. The flow rate regulator 45 outputs a rotation speed command value corresponding to the flow rate command value to the water supply pump P1 based on the characteristics of the water supply pump P1 (relationship between the rotation speed and the flow rate), thereby controlling the water supply pump P1. . The flow controller 46 controls a liquid feed pump P2, which will be described later.

Next, the feed water is preheated by the second exhaust heat recovery unit 6 and the medium cooler 4 as described above.
The preheated supply water is combined with warm water (hereinafter referred to as circulating water) in the gas-liquid separator 7 sent from the pipe L6 to form a mixed water of the circulating water and the supply water. The solution is sent to the condenser 3. The mixed water introduced into the medium condenser 3 recovers the heat of the high-temperature and high-pressure medium (heat pump medium) as described above, generates a gas-liquid two-phase flow of hot water and steam, and drives the liquid feed pump P2. To the gas-liquid separator 7. In the liquid feed pump P2, the flow rate regulator 46 multiplies the flow rate command value of the supplied water by a constant K as the liquid feed pump flow rate, and the characteristics of the liquid feed pump P2 (relationship between the rotational speed and the flow rate) ), The rotational speed command value corresponding to the liquid feed pump flow rate command value is output to the liquid feed pump P2, and the liquid feed pump P2 is controlled.

  In the gas-liquid separator 7, the gas-liquid two-phase flow of hot water and steam is separated into steam and hot water. And the vapor | steam stored in the gaseous-phase part of the gas-liquid separator 7 is taken out from the piping L4 according to an external demand. Further, the hot water stored in the liquid phase part of the gas-liquid separator 7 is mixed with the supply water flowing through the pipe L3a through the pipe L6 and circulated and used.

  The on-off valve V1 provided in the pipe L5 connected to the liquid phase part of the gas-liquid separator 7 is periodically or temporarily controlled to blow down for the purpose of preventing the concentration of salt in the circulating water system. In addition, the opening / closing control based on the pressure and the water level in the gas-liquid separator 7 is performed as follows.

  That is, as shown in FIG. 2, in the open / close setting device 47, the measured value of the pressure gauge 32 of the gas-liquid separator 7 is a preset upper limit value (in this embodiment, 270 kPa · abs (corresponding to 130 ° C.)). ) In the above case, an open signal is output to the open / close selector 49, and in the case of a preset lower limit value (230 kPa · abs (corresponding to 125 ° C.) in this embodiment), the close signal is output to the open / close selector 49, and the open / close setting device 48 outputs an open signal when the measured value of the water level gauge 33 of the gas-liquid separator 7 is a preset upper limit value (65% or more in the present embodiment). The signal is output to the open / close selector 49, and a close signal is output to the open / close selector 49 in the case of a preset lower limit value (60% or less in the present embodiment). In the open / close selector 49, when at least one of both signals inputted from the open / close setter 47 and the open / close setter 48 is open, the open signal is given to the open / close valve V1 as an open / close command value, When is closed, a close signal is given to the open / close valve V1 as an open / close command value.

(Standby operation)
Next, the operation during standby operation will be described.
When the demand for steam decreases, the measured value of the pressure gauge 32 of the gas-liquid separator 7 increases, and the output of the compressor controller 41 sets the lower limit value of the rotational speed command value limited by the upper / lower limiter 42 to the compressor 2. And the rotational speed is lowered to the lowest level to reduce the amount of heat transfer from the heat pump medium to the circulating water in the medium condenser 3.

  When the measured value of the pressure gauge 32 of the gas-liquid separator 7 reaches the upper limit value (270 kPa · abs) of the open / close setter 47, the open / close valve V1 is opened by the open signal from the open / close setter 47, and from the pipe L5 While heat is released by blowdown, supply water corresponding to the blowdown flow rate is supplied accordingly, so that the temperature and pressure in the gas-liquid separator 7 are lowered.

Thus, according to the present invention, the demand for steam is reduced, and the heat supplied from the heat pump medium and the heat released from the pipe L5 are reduced while the supply of steam from the pipe L4 is stopped or reduced. A heat pump standby operation can be performed while balancing.
For this reason, even if the demand for steam increases again, it is possible to respond quickly to the demand.

1: First exhaust heat recovery unit 2: Compressor 3: Medium condenser 4: Medium cooler 5: Expander 6: Second exhaust heat recovery unit 7: Gas-liquid separator 20: Heat pump circulation path 31: Steam flow meter 32: Pressure gauge 33: Water level gauge 41: Compressor controller 42: Upper / lower limit limiter 43: Blowdown flow rate calculator 44: Water level compensator 45, 46: Flow rate regulator 47, 48: Open / close setter 49: Open / close selector L1 L6: Piping P1: Supply pump P2: Liquid feed pump V1: On-off valve

Claims (3)

An exhaust heat recovery unit that recovers heat from an external heat source and heats the medium, a compressor that compresses the medium that has passed through the exhaust heat recovery unit, and transfers the heat of the medium compressed by the compressor to supply water A heat pump circulation path having a medium condenser that generates a gas-liquid two-phase flow of hot water and steam, and an expander that depressurizes and lowers the temperature of the medium that has passed through the medium condenser;
A water supply path for introducing the supply water into the medium condenser;
A gas-liquid separator that separates the gas-liquid two-phase flow of hot water and steam generated by the medium condenser into water vapor and water;
A vapor extraction path provided in a gas phase portion of the gas-liquid separator;
A heat pump type steam generator comprising a water circulation path connecting the liquid phase part of the gas-liquid separator and the water supply path,
Water supply amount adjusting means disposed in the water supply path;
A drainage path provided in the liquid phase part of the gas-liquid separator;
A drainage valve interposed in the drainage path,
When the amount of steam from the steam extraction path is reduced or stopped, the operation of the compressor is lowered to a preset minimum level, the drain valve is opened, and the standby operation for continuing the operation of the heat pump is performed. A heat pump type steam generator characterized by being controlled. As the water supply path arranged supplied water volume adjustment means, a flow rate equal to the sum of the flow rate of waste water discharged from the flow and the discharge water path of the steam withdrawn from the steam extraction route, supplying the feed water The heat pump type steam generator according to claim 1, which is controlled. A pressure gauge for detecting the pressure in the gas-liquid separator;
3. The heat pump steam generation according to claim 1, wherein the valve for drainage is controlled so that a detected value of the pressure gauge is opened at a set value or more and a detected value of the pressure gauge is closed at a set value or less. apparatus.