CN117663564B - Centrifugal steam heat pump gas-liquid separator control system - Google Patents
Centrifugal steam heat pump gas-liquid separator control system Download PDFInfo
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- 241001673669 Porcine circovirus 2 Species 0.000 claims description 8
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Abstract
A control system of a centrifugal steam heat pump gas-liquid separator relates to the field of steam heat pumps. In order to solve the defects that the liquid level control method of the existing gas-liquid separator can generate liquid level fluctuation and pressure fluctuation and is unreliable in operation, the invention presets the liquid level parameter, the pressure relief water discharge parameter and the alarm parameter; monitoring the liquid level information of the liquid level meter, the running states and the running time of the pressure relief device and the water draining device in real time; the controller predicts the change trend of the liquid level according to the opening degree of the steam discharge valve of the gas-liquid separator; the controller generates a water replenishing instruction and an opening and closing instruction of the pressure relief device and the water draining device according to the predicted change trend of the liquid level, the current liquid level height, the water replenishing parameter, the current running state and running time of the pressure relief device and the water draining device. The invention is mainly used for controlling the liquid level stability of the gas-liquid separator and reducing the pressure fluctuation.
Description
Technical Field
The invention relates to the field of steam heat pumps, in particular to a control system of a centrifugal steam heat pump gas-liquid separator.
Background
The centrifugal heat pump unit can directly prepare steam at 100-130 ℃, the condenser is a place where steam is generated, the high-temperature and high-pressure gaseous refrigerant exchanges heat with water to heat the water into two states of vapor and liquid, and the gas-liquid separator is arranged on the condenser to separate the two states of vapor and liquid to generate steam. In the existing steam heat pump system, maintaining the liquid level of the gas-liquid separator stable is an important means for ensuring that the pressure and flow of the output steam of the steam heat pump are kept stable. At present, a three-way valve or an electromagnetic valve is generally adopted for intermittently supplementing water to the gas-liquid separator, the intermittent water supplementing enables the liquid level of the gas-liquid separator to fluctuate among a plurality of electrode plates, and the pressure and the gas yield in the gas-liquid separator also fluctuate due to the fluctuation of the liquid level. The existing liquid level control of the gas-liquid separator comprises the following steps of:
1. the liquid level is collected through a plurality of electrode plates, and then a three-way valve or an electromagnetic valve is controlled to intermittently supplement water to the gas-liquid separator, so that the fluctuation of the liquid level between a low liquid level and a high liquid level is maintained, and the water in the condenser is ensured to be always present;
2. the water supplementing amount is controlled by controlling the opening of a valve at the outlet of the water supplementing pump, so that the liquid level is maintained stable.
However, the water replenishing source of the water replenishing mode adopts a water source on site of a user, and the water temperatures on site of different users are different, so that the water replenishing temperature is different from the water temperature difference of the condenser and the gas-liquid separator. When the temperature difference between the water temperature of the water replenishing and the water temperature of the condenser and the gas-liquid separator is large, the water in the condenser or the gas-liquid separator is easy to stop boiling, when the liquid level of the gas-liquid separator is low and a large amount of water replenishing is needed, the liquid level of the gas-liquid separator is lower due to condensation of hot water, when the water in the gas-liquid separator boils, a large amount of steam bubbles occupy the position of liquid water, so that the liquid level rises, the liquid level fluctuation of the gas-liquid separator is large, the working conditions of the gas-liquid separator and the condenser are fluctuation due to the large liquid level fluctuation, and stable steam is unfavorable to be produced.
Secondly, the water supplementing is controlled through the opening degree of the valve at the outlet of the water supplementing pump, so that the water supplementing pressure is unstable, the water supplementing quantity is difficult to control, and the fluctuation of the liquid level and even the fluctuation of the pressure and the gas yield in the gas-liquid separator are caused.
In summary, the water replenishing of the vapor-liquid separator based on the current vapor heat pump adopts the water source on the site of the user, and the water temperatures on the site of different users are different, so that the liquid level fluctuation and the pressure fluctuation of the vapor-liquid separator are both large due to the superposition of the factors, and the operation is unreliable.
Therefore, there is a need for a centrifugal vapor heat pump vapor-liquid separator control system that can control the vapor-liquid separator to have a stable liquid level, small pressure fluctuations, stable vapor generation, and high reliability.
Disclosure of Invention
The invention provides a centrifugal steam heat pump gas-liquid separator control system capable of maintaining stable liquid level, small pressure fluctuation and reliable operation, and aims to solve the defects that the liquid level control method of the existing gas-liquid separator can generate liquid level fluctuation, pressure fluctuation and unreliable operation.
The invention relates to a control system of a centrifugal steam heat pump gas-liquid separator, which comprises an evaporator, a compressor, a condenser and an economizer, wherein a water inlet of the evaporator is communicated with heat source water, a refrigerant outlet of the evaporator is communicated with a suction port of the compressor, an exhaust port of the compressor is communicated with a gaseous refrigerant inlet of the condenser, and a liquid refrigerant outlet of the condenser is communicated with a liquid refrigerant inlet of the evaporator; the air outlet of the economizer is communicated with the air supplementing port of the compressor, and the liquid outlet of the economizer is communicated with the refrigerant inlet of the evaporator;
the system also comprises a gas-liquid separator, a water supplementing device, a subcooler, a liquid level meter, a pressure relief device and a water draining device; the gas-liquid two-phase inlet of the gas-liquid separator is communicated with the gas-liquid two-phase outlet of the condenser, and the water outlet of the gas-liquid separator is connected to the water inlet of the condenser; the water inlet of the subcooler is communicated with the water outlet of the water supplementing device, and the water outlet of the subcooler is communicated with the water inlet of the condenser; the refrigerant inlet of the subcooler is communicated with the liquid refrigerant outlet of the condenser, the refrigerant outlet of the subcooler is communicated with the refrigerant inlet of the economizer, the subcooler is used for heating water in the water supplementing pipeline, and meanwhile, the refrigerant flowing to the economizer from the condenser is subcooled, so that the system efficiency is improved.
The liquid level meter is used for measuring the liquid level in the gas-liquid separator; the pressure relief device is arranged at the upper end of the gas-liquid separator and is used for relieving pressure when the gas-liquid separator is overpressurized; the water draining device is arranged at the lower end of the gas-liquid separator and is used for draining water when the liquid level in the gas-liquid separator is ultrahigh; the water supplementing device comprises a controller; the execution parts of the liquid level meter, the pressure relief device and the water draining device are all in communication connection with the controller;
the control method of the centrifugal steam heat pump gas-liquid separator control system comprises the following steps:
s1: presetting a liquid level parameter, a pressure parameter, a water supplementing parameter and an alarm parameter;
s2: monitoring the liquid level information of the liquid level meter, the operation states of the pressure relief device and the water draining device in real time;
s3: the controller predicts the change trend of the liquid level according to the opening degree of the steam discharge valve of the gas-liquid separator;
s4: the controller generates a water supplementing instruction, an opening and closing instruction of the pressure relief device and an opening and closing instruction of the water draining device according to the predicted change trend of the liquid level, the current liquid level height L, the water supplementing parameter, the running states and the running time of the current pressure relief device and the water draining device.
Further: the centrifugal steam heat pump also comprises a pressure control valve and a pressure sensor, wherein the pressure control valve is in communication connection with the controller and is used for regulating and controlling the pressure of the steam outlet pipeline according to the instruction of the controller, so that the steam pressure of the steam outlet is kept stable; the pressure sensor is used for sensing the pressure in the steam outlet pipeline, the pressure sensor is in communication connection with the pressure control valve, the water supplementing device comprises a water supplementing pump, one side of the water supplementing pump is communicated with the water supply inlet, and the other side of the water supplementing pump is communicated with the water inlet of the subcooler.
Further: the liquid level parameters comprise a current liquid level height L, a drainage liquid level L1, a control high liquid level L2, a control low liquid level L3 and an alarm low liquid level L4, wherein L1 is more than L2 and more than L3 is more than L4; the pressure parameter includes an opening PCV of the pressure control valve; the water supplementing parameters comprise output frequency V of the water supplementing pump, maximum frequency V1 of the water supplementing pump, minimum frequency V2 of the water supplementing pump, calculated frequency V3 of the water supplementing pump, high liquid level water supplementing coefficient K1 and low liquid level water supplementing coefficient K2;
the water replenishing instruction is the output frequency V of the water replenishing pump, and the calculating method specifically comprises the following steps:
V=V3*K；
V3=（V1-V2）*PCV+V2；
K=（K1-K2）*（L-L3）/（L2-L3）+K2。
further: the pressure relief device comprises a pressure relief valve and a safety valve, the pressure relief valve is arranged on a steam outlet pipeline of the gas-liquid separator, the safety valve is arranged on one side, far away from the gas-liquid separator, of the pressure relief valve, and the pressure relief valve is in communication connection with the controller; the water draining device comprises a water draining valve which is in communication connection with the controller.
Further: still include high temperature circulating water pump and return water temperature sensor, high temperature circulating water pump set up in return water pipeline between gas-liquid separator and the condenser, return water temperature sensor sets up on the pipeline between high temperature circulating water pump and gas-liquid separator.
Further: two channels of a gaseous refrigerant return channel and a liquid refrigerant return channel are arranged between the condenser and the evaporator, wherein a throttling device for reducing pressure is arranged on each of the two channels.
Further: the pressure parameters also comprise a water supplementing opening PCV1, a water stopping opening PCV2 and a water draining valve running time T2;
in S4, the specific process of the controller generating the water replenishing instruction, the pressure release valve and the opening and closing instruction of the water drain valve according to the current liquid level height L of the liquid level gauge, the water replenishing parameter, the current pressure release valve, the running state of the water drain valve and the running time T2 includes the following steps:
s41: when in shutdown:
when L is less than L3, the water supplementing pump starts to operate;
when L is more than or equal to L3+Diff1, the water supplementing pump stops running;
when L is more than L2, the water drain valve is opened, and when L is less than L3+Diff2, the water drain valve is closed;
s42: when the machine is started up:
when L is less than or equal to L2 and PCV is less than or equal to PCV1, the water supplementing pump starts to operate according to the output frequency V of the water supplementing pump; when L is more than L2 and PCV is less than PCV2, the water supplementing pump stops running;
when L is more than or equal to L1, opening a water drain valve; when L < L3+Diff2, the water drain valve is closed.
Further: the alarm parameters comprise water supplementing pump running time T1, a water supplementing pump fault signal, a water draining fault signal, a water supplementing pump delay threshold T3 and a water draining valve delay threshold T4; in S4, the following fault instructions are also included:
s41: when in shutdown:
after the water supplementing pump starts to operate, when T1 is more than T3, the water supplementing pump gives an alarm when the water supplementing pump fails, and the water supplementing pump stops operating;
after the water draining valve is opened, when T2 is more than T4, the water draining device gives an alarm, and the controller sends out an instruction to control the water draining valve to be closed;
s42: when the machine is started up:
after the water supplementing pump starts to operate, when L is less than or equal to L4, the water draining device gives an alarm and stops;
after the water discharge valve is opened, when T2 is more than T4, the water discharge system is in fault alarm and stop.
The beneficial effects of the invention are as follows:
according to the invention, the opening degree of the pressure control valve on the steam outlet of the gas-liquid separator is monitored to predict the liquid level falling speed, and the adaptive output frequency of the water supplementing pump is obtained through calculation, so that the water supplementing amount of the water supplementing pump and the discharge amount of steam are balanced, and the liquid level in the gas-liquid separator is always stabilized in a small fluctuation range, so that the liquid level and the pressure of the gas-liquid separator are stabilized, and the reliability of stably generating steam is improved. The output of the water supplementing pump frequency is related to the liquid level coefficient, so that the overshoot can be prevented, and the steady state performance of liquid level control and pressure control is improved.
The liquid level is continuously monitored in the shutdown stage, the gas-liquid separator is controlled at a certain height, independent water supplementing or water draining is not needed when the machine is started next time, the preparation time before the machine is started is shortened, and the starting speed of the machine set is improved.
Drawings
FIG. 1 is a schematic diagram of a centrifugal vapor heat pump vapor-liquid separator control system;
FIG. 2 is a partial schematic view of a portion of a condenser of a centrifugal vapor heat pump vapor-liquid separator;
FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2;
FIG. 4 is a schematic diagram of a control flow of the gas-liquid separator in a shutdown state;
fig. 5 is a schematic diagram of a control flow of the gas-liquid separator in the on state.
In the figure, 1, a condenser; 2. a compressor; 3. an evaporator; 4. an economizer; 5. a gas-liquid separator; 6. a water supplementing pump; 7. a check valve; 8. a water replenishment temperature sensor; 9. a high-temperature circulating water pump; 10. a water drain valve; 11. a liquid level gauge; 12. a pressure release valve; 13. a safety valve; 14. a pressure sensor; 15. a pressure control valve; 16. a backwater temperature sensor; 17. a water supplementing bundling pipe; 18. a partition board.
Detailed Description
The following preferred embodiments of the present invention are provided, but the scope of the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. The examples described below are only for the purpose of illustrating the invention and should not be construed as limiting the invention, which is intended to be covered by the claims. The following detailed description of embodiments of the invention is provided for convenience in describing the invention and simplifying the description, and technical terms used in the description of the invention should be construed broadly, including but not limited to conventional alternatives not mentioned in the present application, including both direct implementation and indirect implementation.
In addition, the drawings are schematic views, mainly showing technical features related to the scheme of the invention, so that all structural details in the real equipment are not drawn.
Example 1
Referring to fig. 1, a control system of a centrifugal vapor heat pump vapor-liquid separator disclosed in the present embodiment is described, where the centrifugal vapor heat pump includes a condenser 1, a compressor 2, an evaporator 3, and an economizer 4, a water inlet of the evaporator 3 is in water communication with a heat source, a refrigerant outlet of the evaporator 3 is in communication with an air suction port of the compressor 2, an air outlet of the compressor 2 is in communication with a refrigerant inlet of the condenser 1, and a liquid refrigerant outlet of the condenser 1 is in communication with a liquid refrigerant inlet of the evaporator 3; the refrigerant inlet of the economizer 4 is communicated with the liquid refrigerant outlet of the subcooler, the air outlet of the economizer 4 is communicated with the air supplementing port of the compressor 2, and the liquid outlet of the economizer 4 is communicated with the refrigerant inlet of the evaporator 3; the compressor 2 is a centrifugal compressor.
The evaporator 3 is used for heating the liquid refrigerant inside to generate gaseous refrigerant and delivering the gaseous refrigerant into the compressor 2; the evaporator 3 vaporizes the liquid refrigerant by extracting heat from the heat source water flowing through the interior of the evaporator 3, thereby reducing the temperature of the heat source water.
The compressor 2 compresses a low-temperature low-pressure gaseous refrigerant from the evaporator 3 and a gaseous refrigerant flashed in the economizer 4 into a high-temperature high-pressure gaseous refrigerant, and then sends the high-temperature high-pressure gaseous refrigerant to the condenser 1.
The condenser 1 is used for condensing the high-temperature high-pressure gaseous refrigerant into liquid refrigerant and returning the liquid refrigerant to the evaporator 3 for circulation; meanwhile, the condenser 1 further heats the water output by the subcooler to form high-temperature steam and transmits the high-temperature steam to the gas-liquid separator 5; the vapor in the two states of gas and liquid in the condenser 1 enters the gas-liquid separator 5, the vapor in the gas state is output from the vapor outlet, and the unvaporized liquid water flows back to the condenser 1 to be heated continuously, namely the condenser 1 is a vapor generator.
The control system also comprises a gas-liquid separator 5, a water supplementing device, a subcooler, a liquid level meter 11, a pressure relief device and a water draining device; the gas-liquid two-phase inlet of the gas-liquid separator 5 is communicated with the gas-liquid two-phase outlet of the condenser 1, and the water outlet of the gas-liquid separator 5 is connected to the water inlet of the condenser 1; the hot water that is not vaporized in the gas-liquid separator 5 returns to the condenser 1 to continue absorbing heat and is heated to steam.
The subcooler is arranged at the bottom of the interior of the condenser 1 and integrated with the condenser 1, and after the refrigerant condensed in the condenser 1 is collected, the refrigerant flows through the subcooler again to exchange heat with cold water in the water supplementing pipeline, so that the temperature of the water in the water supplementing pipeline is increased, and meanwhile, the refrigerant is supercooled; more specifically, as shown in fig. 1, 2 and 3, the upper condenser 1 and the lower Fang Guoleng are separated by a partition 18, two ends of the partition 18 separating the condenser 1 and the subcooler are provided with liquid refrigerant inlets, a plurality of partition boards are arranged in the subcooler, further referring to fig. 3, a plurality of water supplementing bundling pipes 17 are arranged in the subcooler, the supplemented water flows through the water supplementing bundling pipes 17, the liquid refrigerant flows through the outside of the water supplementing bundling pipes 17, heat exchange is realized between the two water supplementing bundling pipes, the partition boards in the subcooler are used for guiding the liquid refrigerant to move in a curve in the subcooler, the contact stroke of the liquid refrigerant and the water supplementing bundling pipes 17 is improved, the heat exchange effect is improved, the water inlet of the subcooler is communicated with the water outlet of the water supplementing device, the water outlet of the subcooler is communicated with the water inlet of the condenser 1, the refrigerant outlet of the subcooler is communicated with the liquid refrigerant outlet of the condenser 1, the water supplementing device is heated by the subcooler, and the water supplementing device is supplemented by the water in the condenser 1.
The liquid level meter 11 is used for measuring the liquid level in the gas-liquid separator 5 and transmitting the liquid level to the water supplementing device; the pressure relief device is arranged at the upper end of the gas-liquid separator 5 and used for releasing pressure when the gas-liquid separator 5 is overpressurized, and the water draining device is arranged at the lower end of the gas-liquid separator 5 and used for draining water when the liquid level in the gas-liquid separator 5 is ultrahigh; the water supplementing device comprises a controller; the controller is used for calculating the water supplementing frequency; the execution parts of the liquid level meter 11, the pressure relief device and the water draining device are all in communication connection with the controller.
The control method of the centrifugal steam heat pump gas-liquid separator control system comprises the following steps:
s1: presetting a liquid level parameter, a pressure parameter, a water supplementing parameter and an alarm parameter;
s2: monitoring the liquid level information of the liquid level meter 11, the running states and the running time of the pressure relief device and the water drainage device in real time;
s3: the controller predicts the change trend of the liquid level according to the opening degree of the steam discharge valve of the gas-liquid separator 5;
s4: the controller generates a water supplementing instruction, an opening and closing instruction of the pressure relief device and an opening and closing instruction of the water draining device according to the predicted change trend of the liquid level, the current liquid level height L, the water supplementing parameter, the running states and the running time of the current pressure relief device and the water draining device.
The water replenishing device comprises a water replenishing pump 6, a check valve 7 and a water replenishing temperature sensor 8, one side of the water replenishing pump 6 is communicated with a water supply inlet, the other side of the water replenishing pump 6 is communicated with a water inlet of the subcooler through the check valve 7, and an induction end of the water replenishing temperature sensor 8 is connected to a pipeline between the check valve 7 and the subcooler.
The control system further comprises a pressure control valve 15 and a pressure sensor 14, wherein the pressure control valve 15 is arranged on a steam outlet pipeline of the gas-liquid separator 5 and is in communication connection with the controller, and is used for regulating and controlling the pressure of the steam outlet pipeline according to instructions of the controller, so that the steam pressure of the steam outlet is kept stable. The pressure sensor 14 is arranged on a pipeline between the gas-liquid separator 5 and the pressure control valve 15, and the pressure sensor 14 is used for collecting steam pressure. The pressure sensor 14 is in communication with a pressure control valve 15.
The pressure relief device comprises a pressure relief valve 12 and a safety valve 13, wherein the pressure relief valve 12 is arranged on a steam outlet pipeline of the gas-liquid separator 5, the pressure relief valve 12 is used for preventing the pressure in the gas-liquid separator 5 from being too high, the safety valve 13 is arranged on one side, far away from the gas-liquid separator 5, of the pressure relief valve 12, the pressure relief valve 12 is in communication connection with a controller, the safety valve 13 is a purely mechanical safety valve, and pressure relief can be automatically opened without any control instruction when the pressure of the gas-liquid separator 5 exceeds a set value. The drain device comprises a drain valve 10, wherein the drain valve 10 is in communication connection with a controller.
The control system further comprises a high-temperature circulating water pump 9 and a backwater temperature sensor 16, wherein the high-temperature circulating water pump 9 is arranged on a backwater pipeline between the gas-liquid separator 5 and the condenser 1, and the backwater temperature sensor 16 is arranged on a pipeline between the high-temperature circulating water pump 9 and the gas-liquid separator 5.
The upper part between the condenser 1 and the evaporator 3 is provided with a gaseous refrigerant pipeline and the lower part is provided with a liquid refrigerant pipeline, the two pipelines are respectively used for flowing through the gaseous refrigerant and the liquid refrigerant (increasing the liquid supply amount of the evaporator 3) between the condenser 1 and the evaporator 3, a gaseous pressure reducing control valve HG is arranged on a gaseous refrigerant return pipeline, and a liquid pressure reducing valve BP is arranged on a liquid refrigerant return pipeline. The air suction port of the compressor 2 is provided with an air inlet guide vane valve IGV, the gaseous refrigerant belongs to a hot gas bypass pipeline, when the unit operates in a low load mode, heat required to be externally supplied is small, even the power of the compressor 2 is reduced to be minimum and exceeds the requirements of the outside, at the moment, high-temperature steam in the condenser 1 is introduced into the evaporator through the hot gas bypass, the temperature of the refrigerant in the evaporator 3 is increased, the heat absorption capacity of the refrigerant in the evaporator 3 is reduced, and then the refrigerant returns to the condenser 1 through the compressor 2, and because the heat absorbed in the evaporator 3 is reduced, the compressor 2 can continuously operate under a higher working condition, namely the opening degree of the air inlet guide vane can be maintained at a larger opening degree, the condition that the opening degree of the guide vane is excessively low to adapt to the low load requirement on site is avoided, the system is in an unstable state, and the low guide vane opening degree can possibly bring extra vibration and even cause the unit to occur.
Example 2
The present embodiment is described with reference to fig. 4, 5 and embodiment 1, and the control method of the centrifugal steam heat pump gas-liquid separator disclosed in the present embodiment is as follows:
s1: presetting a liquid level parameter, a pressure parameter, a water supplementing parameter, an alarm parameter and a time delay threshold; the liquid level parameters comprise the current liquid level L, a water draining liquid level L1, a control high liquid level L2, a control low liquid level L3 and an alarm low liquid level L4, the pressure parameters comprise the opening PCV of the pressure control valve 15, the water supplementing opening PCV1 of the pressure control valve 15, the water stopping opening PCV2 of the pressure control valve 15 and the running time T2 of the water draining valve 10, the alarm parameters comprise the running time T1 of the water supplementing pump 6, a fault signal of the water supplementing pump 6 and a water draining fault signal, the water supplementing parameters comprise the output frequency V of the water supplementing pump 6, the maximum frequency V1 of the water supplementing pump 6, the minimum frequency V2 of the water supplementing pump 6, the calculation frequency V3 of the water supplementing pump 6, the high liquid level water supplementing number K1 and the low liquid level water supplementing number K2, and the delay threshold comprises the delay threshold T3 of the water supplementing pump 6 and the delay threshold T4 of the water draining valve 10;
s2: the current liquid level height of the liquid level meter 11, the pressure relief valve 12, the running state of the water drain valve 10 and the running time are monitored in real time; the liquid level meter 11 adopts a magnetostrictive float liquid level meter 11, and the magnetostrictive liquid level meter 11 outputs an analog signal to collect the current liquid level height L, and a drainage liquid level L1, a control high liquid level L2, a control low liquid level L3 and an alarm low liquid level L4 are arranged in the controller, wherein L1 is more than L2 and more than L3 is more than L4;
s3: the controller predicts the change trend of the liquid level according to the opening degree of the steam discharge valve of the gas-liquid separator 5;
s4: the controller generates a water replenishing instruction, an opening and closing instruction of the pressure relief valve 12 and an opening and closing instruction of the water relief valve 10 according to the predicted change trend of the liquid level, the current liquid level height L, the water replenishing parameter, the current pressure relief valve 12, the running state of the water relief valve 10 and the running time T2.
In S4, the specific process of the controller generating the water replenishment instruction, the pressure relief valve 12 and the opening and closing instruction of the water drain valve 10 according to the current liquid level height L of the liquid level meter 11, the water replenishment parameter, the current pressure relief valve 12, the running state of the water drain valve 10 and the running time T2 includes the following steps:
s41: when in shutdown:
in the shutdown, the liquid level in the gas-liquid separator 5 is controlled at a certain height, so that the situation that the liquid level is too high to bring liquid into steam after the next startup is prevented, the condenser 1 is dry-burned due to the too low liquid level, or long-time water supplementing or water draining is needed when the unit is started up, and the unit cannot be rapidly put into use is avoided.
When L is smaller than L3, namely the current liquid level height L of the gas-liquid separator 5 is smaller than the control low liquid level L3, the water supplementing pump 6 starts to operate; for example, the frequency of the water replenishment pump 6 is set to 80% (settable) of the maximum frequency of the water replenishment pump 6.
When L is more than or equal to L3+Diff1, namely the current liquid level height L of the gas-liquid separator 5 is more than or equal to a certain height Diff1 of the control low liquid level L3+, the water supplementing pump 6 stops running; when T1 is more than T3, that is, the actual running time T1 of the water supplementing pump 6 is more than the time delay threshold T3 of the water supplementing pump 6, the running of the water supplementing pump 6 does not reach the predicted liquid level rising effect, and the water supplementing pump 6 is very likely to have faults, so that the water supplementing pump 6 is set as a fault alarm and stops running at the moment; for example, setting T3 to 600s, in theory, the water replenishment pump 6 should be able to replenish the liquid level to LΣ3+Diff1 for 600s continuously running at 80% frequency, but if LΣ3+Diff1 is not detected after 600s running, the water replenishment pump 6 is considered to be likely to be faulty, so when the water replenishment pump 6 runs for more than 600s (settable), the default water replenishment has an abnormal problem, and the operation of the water replenishment pump 6 is alerted and stopped.
When L is more than L2, namely the current liquid level L of the gas-liquid separator 5 is more than the control high liquid level L2, the liquid level is too high, the water drain valve 10 is opened to drain water, and when the liquid level L is less than L3+Diff2, namely the current liquid level L is less than the control low liquid level L3+a certain height Diff2 (settable), the water is already put to a reasonable liquid level, and the water drain valve 10 is closed; when T2 is more than T4, namely the running time T2 of the water drain valve 10 is more than the delay threshold T4 of the water drain valve 10, the default water drain device is in fault, fault alarm is set, and the water drain valve 10 is closed; for example, when T4 is 600s, it means that 600s after the water drain valve 10 is opened, theoretically, the liquid level must be reduced to L < l3+diff2, and if the water drain valve 10 is kept in an opened state for more than 600s (can be set), the liquid level is still not lower than l3+diff2, the water drain device may have a fault, and the controller sends an instruction to close the water drain valve 10 and gives an alarm.
Wherein, setting of Diff1 and Diff2 avoids frequent start-up and stop of the device.
S42: when the machine is started up:
after the machine is started, the liquid level in the gas-liquid separator 5 can be gradually increased, when L is less than or equal to L2 and PCV is more than or equal to PCV1, namely the current liquid level height L of the gas-liquid separator 5 is less than or equal to the control high liquid level L2 and the opening PCV of the pressure control valve 15 is greater than the water supplementing opening PCV1, the system is normally supplying steam outwards, water is inevitably continuously lost, and at the moment, the water supplementing pump 6 starts to operate according to the output frequency V of the water supplementing pump 6; for example, when the PCV1 is set to 10% of the total opening of the pressure control valve 15, the liquid level L in the gas-liquid separator 5 is less than or equal to the control high liquid level L2, and when the opening PCV of the pressure control valve 15 is more than or equal to 10%, the water supplementing pump 6 starts to operate according to the current output frequency V for supplementing water;
when L is less than or equal to L4, namely the current liquid level L of the gas-liquid separator 5 is less than or equal to the alarm low liquid level L4, the current liquid level is too low, the water supplementing pump 6 is operated at the maximum frequency V1 (settable) for 60s so as to supplement the liquid level as soon as possible, then whether the current liquid level L of the gas-liquid separator 5 exceeds the alarm low liquid level L4 is judged again, if so, the system enters a safe state, the water supplementing is continued according to the plan, otherwise, when the liquid level is still less than or equal to the alarm low liquid level L4 after the water supplementing pump 6 is operated at the maximum frequency V1 for 60s, the system is likely to have the water leakage problem, the system is forced to stop after failure, and the expansion of the failure is avoided.
According to the method, the liquid level of the gas-liquid separator 5 is ensured, so that a certain liquid level is always kept in the condenser 1, and serious accidents such as heating pipe burning and pipe explosion caused by too high heating pipe temperature rise due to too low liquid level in the condenser 1 are prevented; too low liquid level can also cause scale in the condenser 1 to increase, influence the heat transfer effect and reduce the equipment efficiency; when the liquid level is too low, the hot water in the condenser 1 can be vaporized rapidly, the pressure is increased suddenly, and then the steam flow rate in the steam pipeline is increased to form an air hammer, so that the safety of equipment is affected.
When L is larger than L2 and PCV is smaller than PCV2, namely the current liquid level L of the gas-liquid separator 5 is larger than the control high liquid level L2, and the opening PCV of the pressure control valve 15 is smaller than the water cut-off opening PCV2, the fact that the externally supplied steam is very small at present is that the system is likely to be in a shutdown process, and the water supplementing pump 6 stops running at the moment; for example, when the water cut-off opening PCV2 is 5%, that is, the opening PCV of the pressure control valve 15 is less than 5%, the water replenishment pump 6 stops operating.
After the water supplementing pump 6 stops running, 60 seconds (can be set) is passed, whether the current liquid level L of the gas-liquid separator 5 is greater than or equal to the L1 water draining liquid level is judged, if yes, a water draining valve 10 is opened to drain water, steam discharged by the gas-liquid separator 5 with overhigh liquid level is prevented from carrying liquid, the water in a pipeline is increased by the steam carrying liquid, water hammer is possibly formed in the pipeline due to overmuch water, and impact damage is caused to the pipeline and equipment; the steam with water can cause uneven temperature in the pipeline, thereby affecting the working efficiency and the service life of subsequent equipment; steam with water increases the energy consumption of the device because additional energy is required to evaporate the water into steam; steam with water can cause excessive pressure inside the equipment, thereby causing safety hazards to equipment and personnel.
When L < l3+diff2, i.e. when the current liquid level L of the gas-liquid separator 5 is smaller than the control low liquid level l3+a certain height diff2 (settable), it is indicated that the water level has entered a safe range, the water drain valve 10 is closed. When T2 > T4, i.e. the running time T2 of the water discharge valve 10 is greater than the time delay threshold T4 of the water discharge valve 10, the water discharge valve 10 is opened for a long time, but the water level does not reach the expected drop, and the water discharge system is likely to be in fault, so that the water discharge system reports fault, alarms and stops. For example, t4=600s, the drain valve 10 operates for a time T2 greater than 600s (settable), and the drain system fails to alarm for a shutdown.
In S4, the method for calculating the output frequency V of the water compensating pump 6 specifically includes:
V=V3*K；
V3=（V1-V2）*PCV+V2；
K=（K1-K2）*（L-L3）/（L2-L3）+K2。
the output frequency V of the water replenishment pump 6 is frequency-output based on the maximum frequency V1 (settable) of the water replenishment pump 6, the minimum frequency V2 (settable) of the water replenishment pump 6, the calculated frequency V3 of the water replenishment pump 6, the opening PCV of the pressure control valve 15, the high-level water replenishment number K1 (settable), and the low-level water replenishment coefficient K2 (settable).
In this embodiment, the working frequency of the water supplementing pump 6 is related to the opening degree of the gas-liquid separator 5, and the liquid level change trend is foreseen in advance according to the opening degree of the gas-liquid separator 5, so that the water supplementing amount is predictive, the liquid level in the gas-liquid separator 5 can be always kept in a small fluctuation range, the accurate control of the liquid level of the gas-liquid separator 5 is realized, the situation that the liquid level frequently fluctuates between a low liquid level and a high liquid level in the traditional liquid level control is avoided, and the stability of the liquid level control and the pressure control is improved.
Claims (8)
1. A centrifugal steam heat pump gas-liquid separator control system, the centrifugal steam heat pump comprises an evaporator (3), a compressor (2), a condenser (1) and an economizer (4), wherein a water inlet of the evaporator (3) is communicated with heat source water, a refrigerant outlet of the evaporator (3) is communicated with a suction port of the compressor (2), an exhaust port of the compressor (2) is communicated with a gaseous refrigerant inlet of the condenser (1), and a liquid refrigerant outlet of the condenser (1) is communicated with a liquid refrigerant inlet of the evaporator (3); the air outlet of the economizer (4) is communicated with the air supplementing port of the compressor (2), and the liquid outlet of the economizer (4) is communicated with the refrigerant inlet of the evaporator (3);
the device is characterized by further comprising a gas-liquid separator (5), a water supplementing device, a subcooler, a liquid level meter (11), a pressure relief device and a water draining device; the gas-liquid two-phase inlet of the gas-liquid separator (5) is communicated with the gas-liquid two-phase outlet of the condenser (1), and the water outlet of the gas-liquid separator (5) is connected to the water inlet of the condenser (1); the water inlet of the subcooler is communicated with the water outlet of the water supplementing device, and the water outlet of the subcooler is communicated with the water inlet of the condenser (1); the refrigerant inlet of the subcooler is communicated with the liquid refrigerant outlet of the condenser (1), the refrigerant outlet of the subcooler is communicated with the refrigerant inlet of the economizer (4), and the subcooler is used for heating water in a water supplementing pipeline and supercooling the refrigerant flowing to the economizer (4) from the condenser (1);
the liquid level meter (11) is used for measuring the liquid level in the gas-liquid separator (5); the pressure relief device is arranged at the upper end of the gas-liquid separator (5) and is used for relieving pressure when the gas-liquid separator (5) is overpressurized; the water draining device is arranged at the lower end of the gas-liquid separator (5) and is used for draining water when the liquid level in the gas-liquid separator (5) is ultrahigh; the water supplementing device comprises a controller; the execution parts of the liquid level meter (11), the pressure relief device and the water draining device are all in communication connection with the controller;
the control method of the centrifugal steam heat pump gas-liquid separator control system comprises the following steps:
s1: presetting a liquid level parameter, a pressure parameter, a water supplementing parameter and an alarm parameter;
s2: monitoring the liquid level information of the liquid level meter (11), the operation states of the pressure relief device and the water drainage device in real time;
s3: the controller predicts the change trend of the liquid level according to the opening degree of the steam discharge valve of the gas-liquid separator (5);
s4: the controller generates a water replenishing instruction and an opening and closing instruction of the pressure relief device and the water draining device according to the predicted change trend of the liquid level, the current liquid level height L, the water replenishing parameter, the running states and the running time of the current pressure relief device and the water draining device.
2. A centrifugal steam heat pump gas-liquid separator control system according to claim 1, further comprising a pressure control valve (15) and a pressure sensor (14), the pressure control valve (15) being communicatively connected to the controller for regulating the pressure of the steam outlet line according to the instructions of the controller, so as to keep the steam pressure of the steam outlet stable; the pressure sensor (14) is used for sensing the pressure in the steam outlet pipeline, the pressure sensor (14) is in communication connection with the pressure control valve (15), the water supplementing device comprises a water supplementing pump (6), and the water outlet of the water supplementing pump (6) is communicated with the water inlet of the subcooler.
3. A centrifugal steam heat pump gas-liquid separator control system according to claim 2, wherein the liquid level parameters comprise a current liquid level height L, a drain liquid level L1, a control high liquid level L2, a control low liquid level L3 and an alarm low liquid level L4, and L1 > L2 > L3 > L4; the pressure parameter includes an opening degree PCV of a pressure control valve (15); the water supplementing parameters comprise output frequency V of the water supplementing pump (6), maximum frequency V1 of the water supplementing pump (6), minimum frequency V2 of the water supplementing pump (6), calculated frequency V3 of the water supplementing pump (6), high liquid level water supplementing coefficient K1 and low liquid level water supplementing coefficient K2;
the water supplementing instruction is the output frequency V of the water supplementing pump (6), and the calculating method specifically comprises the following steps:
V=V3*K；
wherein v3= (V1-V2) pcv+v2;
K=（K1-K2）*（L-L3）/（L2-L3）+K2。
4. a centrifugal steam heat pump gas-liquid separator control system according to claim 3, characterized in that the pressure relief device comprises a pressure relief valve (12) and a safety valve (13), the pressure relief valve (12) is arranged on a steam outlet pipeline of the gas-liquid separator (5), the safety valve (13) is arranged on one side of the pressure relief valve (12) away from the gas-liquid separator (5), and the pressure relief valve (12) is in communication connection with a controller; the water draining device comprises a water draining valve (10), and the water draining valve (10) is in communication connection with a controller.
5. The control system of a centrifugal steam heat pump gas-liquid separator according to claim 1, further comprising a high-temperature circulating water pump (9) and a backwater temperature sensor (16), wherein the high-temperature circulating water pump (9) is arranged on a backwater pipeline between the gas-liquid separator (5) and the condenser (1), and the backwater temperature sensor (16) is arranged on a pipeline between the high-temperature circulating water pump (9) and the gas-liquid separator (5).
6. A control system of a centrifugal steam heat pump gas-liquid separator according to claim 1, characterized in that two channels of a gaseous refrigerant return channel and a liquid refrigerant return channel are arranged between the condenser (1) and the evaporator (3), wherein a throttling device for reducing pressure is arranged on both channels.
7. A centrifugal steam heat pump gas-liquid separator control system according to claim 4, wherein the pressure parameters further comprise a water replenishment opening PCV1, a water shut-off opening PCV2, a drain valve (10) run time T2;
in S4, the specific process of the controller generating the water replenishing instruction, the pressure release valve (12) and the opening and closing instruction of the water release valve (10) according to the current liquid level height L of the liquid level meter (11), the water replenishing parameter, the current pressure release valve (12), the running state of the water release valve (10) and the running time T2 includes the following steps:
s41: when in shutdown:
when L is less than L3, the water supplementing pump (6) starts to operate;
when L is more than or equal to L3+Diff1, the water supplementing pump (6) stops running;
when L is more than L2, the water drain valve (10) is opened, and when L is less than L3+Diff2, the water drain valve (10) is closed;
s42: when the machine is started up:
when L is less than or equal to L2 and PCV is less than or equal to PCV1, the water supplementing pump (6) starts to operate according to the output frequency V of the water supplementing pump; when L is more than L2 and PCV is less than PCV2, the water supplementing pump (6) stops running;
when L is more than or equal to L1, a water drain valve (10) is opened; when L < L3+Diff2, the water drain valve (10) is closed.
8. A centrifugal steam heat pump gas-liquid separator control system according to claim 7, wherein the alarm parameters comprise a water replenishment pump (6) running time T1, a water replenishment pump (6) fault signal, a water drain fault signal, a water replenishment pump (6) delay threshold T3, a water drain valve (10) delay threshold T4; in S4, the following fault instructions are also included:
s41: when in shutdown:
after the water supplementing pump (6) starts to operate, when T1 is more than T3, the water supplementing pump (6) gives an alarm when a fault occurs, and the water supplementing pump (6) stops operating;
after the water draining valve (10) is opened, when T2 is more than T4, the water draining device gives an alarm on faults, and the controller sends out an instruction to control the water draining valve (10) to be closed;
s42: when the machine is started up:
after the water supplementing pump (6) starts to operate, when L is less than or equal to L4, the water draining device gives an alarm and stops;
after the water discharge valve (10) is opened, when T2 is more than T4, the water discharge system is in fault alarm and stop.
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2024
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| GB450299A (en) * | 1935-01-26 | 1936-07-14 | British Thomson Houston Co Ltd | Improvements in and relating to refrigerators |
| JPH05180538A (en) * | 1991-12-26 | 1993-07-23 | Nippondenso Co Ltd | Water rem0val device of freezing apparatus |
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