Method for regulating superheated steam flow and temperature

Abstract

The application discloses a kind of superheated steam flow and temperature regulating method, set the target flow Qm and target temperature Tm of rotary steam compressor outlet, and the regulating amplitude ΔK of the opening K of backflow temperature rise regulating bypass and the amplitude Δf of frequency f of variable frequency driving system, (1) Qm>Qo, Tm<To, reduce backflow temperature rise regulating bypass opening, K reduces ΔK;(2) Qm<Qo, Tm<To, reduce backflow temperature rise regulating bypass opening, K reduces ΔK, reduce the frequency f of variable frequency driving system, frequency reduces Δf;(3) Qm>Qo, Tm>To, increase backflow temperature rise regulating bypass opening, opening K increases ΔK, increase the frequency f of variable frequency driving system, frequency increases Δf;(4) Qm<Qo, Tm>To, increase backflow temperature rise regulating bypass opening, K increases ΔK.The application can realize the continuous regulation of temperature rise under different flow, improve the temperature rise amplitude of steam, can be aimed at operating condition requirement, realize wide flow, large temperature rise variable condition operation, and not be limited by voltage grade, applicable to power plant heating technical field.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power plant heat supply, in particular to a superheated steam flow and temperature regulation method. BACKGROUND

[0002] With the increasing requirement of energy saving and carbon reduction in China, the proportion of new energy is becoming higher and higher, and the pressure of peak regulation for thermal power units is also increasing. It is a general trend for thermal power units to participate in deep peak regulation. Due to the design characteristics of thermal power units, there are problems in the quality and quantity of steam supply during the peak regulation process of thermal power units, especially during low load operation. How to solve the steam supply problem during low load operation and alleviate the problem of new energy consumption, the electric heat supply method is an effective way. In the electric heat supply method, steam generated by electric boiler and high-pressure high-temperature water flash can be used as steam supply source, but the steam supplied by these methods is saturated steam, and superheated steam is required in many industrial processes. The current conventional treatment method is to use conventional electric superheater such as resistance tube electric superheater for quality upgrading and heating, but this method has certain limitations in actual use.

[0003] 1. Poor temperature and flow control ability, limited temperature rise, poor variable condition regulation;

[0004] 2. Limited by voltage level requirements, cannot be applied to various voltage level requirements;

[0005] 3. Cannot achieve continuous temperature rise under different flow rates. SUMMARY

[0006] The present application provides a superheated steam flow and temperature regulation method, which solves the problems of poor temperature and flow control ability, limited temperature rise, poor variable condition regulation, limited by voltage level requirements, cannot be applied to various voltage level requirements, and cannot achieve continuous temperature rise under different flow rates when using conventional superheating equipment for steam supply quality upgrading and heating in the prior art.

[0007] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0008] A kind of superheated steam flow and temperature regulating method, by frequency conversion drive system control adjustment rotary steam compressor frequency, by backflow temperature rise adjustment bypass control adjustment rotary steam compressor outlet flow, set rotary steam compressor outlet adjustment target flow Qm and target temperature Tm, while setting the amplitude Δf of frequency f of frequency conversion drive system and the adjustment amplitude ΔK of backflow temperature rise adjustment bypass opening K, compare target flow Qm and target temperature Tm with the outlet flow Qo and outlet temperature To of current operation, four kinds of comparison result conditions can appear: (1) Qm>Qo, Tm<To;(2) Qm<Qo, Tm<To;(3)) Qm>Qo, Tm>To;(4)) Qm<Qo, Tm>To, different adjustment actions are taken for the four conditions:

[0009] (1) Qm>Qo, Tm<To, reduce the opening of backflow temperature rise adjustment bypass, reduce the opening K of ΔK;

[0010] (2) Qm<Qo, Tm<To, reduce the opening of backflow temperature rise adjustment bypass, reduce the opening K of ΔK, while reduce the frequency f of frequency conversion drive system, reduce the frequency of Δf;

[0011] (3) Qm>Qo, Tm>To, increase the opening of backflow temperature rise adjustment bypass, increase the opening K of ΔK, while increase the frequency f of frequency conversion drive system, increase the frequency of Δf;

[0012] (4) Qm<Qo, Tm>To, increase the opening of backflow temperature rise adjustment bypass, increase the opening K of ΔK;

[0013] Further, the inlet of the rotary steam compressor is connected with the outlet of the jet mixer, the low-pressure side of the jet mixer is connected with the low-quality steam through a steam supply pipeline, and the high-pressure side is connected with the backflow temperature rise adjustment bypass; one way of the low-quality steam enters the rotary steam compressor through the jet mixer to improve the quality and then enters the heat user through the steam supply pipeline, and the other way of the low-quality steam enters the high-pressure side inlet of the jet mixer through the backflow temperature rise adjustment bypass; the rotary steam compressor is connected with a frequency conversion drive system.

[0014] Further, the backflow temperature rise adjustment bypass is arranged between the outlet of the rotary steam compressor and the inlet of the high-pressure side of the jet mixer, and includes a backflow isolation valve and a backflow regulating valve arranged in series through a pipeline.

[0015] Further, a steam supply regulating valve, a flow meter and a steam temperature meter are arranged on the steam supply pipeline to the heat user, and a low-quality steam temperature meter is arranged on the steam supply pipeline of the low-quality steam.

[0016] Further, the flow meter adopts a perforated plate type, a nozzle type or a vortex type flow meter.

[0017] Further, the inlet and outlet of the rotary vapor compressor is provided with a compressor bypass, and the compressor bypass is provided with a compressor bypass valve.

[0018] Further, the rotary vapor compressor is designed according to the flow size, and can adopt a Roots type, centrifugal type or screw type (single or double screw) vapor compressor.

[0019] Further, the jet flow type mixer is provided with a mixing element in front of the outlet.

[0020] Further, the variable frequency driving system comprises a driving motor for driving the rotary vapor compressor and a frequency converter for adjusting the speed and power of the rotary vapor compressor, and the driving motor is configured as a high-voltage or low-voltage driving motor according to the power requirement.

[0021] Compared with the prior art, the application has the following technical progress: low-quality steam enters the rotary vapor compressor from the inlet, is warmed and regulated in pressure by the rotary vapor compressor, the frequency of the rotary vapor compressor is controlled by the variable frequency driving system, the outlet flow of the rotary vapor compressor is controlled by the backflow temperature rise and bypass, the speed and frequency of the rotary vapor compressor are changed by the variable frequency driving system according to different operating conditions, the opening of the backflow temperature rise and bypass is adjusted, the outlet flow and temperature of the rotary vapor compressor are flexibly adjusted, the temperature and flow regulation performance is improved, the continuous regulation of the temperature rise can be realized under different flows, the temperature rise range of the steam is improved, the wide-flow and large-temperature-rise variable operating condition can be realized according to the operating condition requirement, the variable operating condition is not limited by the voltage level, can be used for various voltage levels, and is suitable for the power plant heating technology field. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application, and are used together with the embodiments to explain the application, and do not constitute a limitation on the application.

[0023] In the drawings:

[0024] Figure 1 The flow chart of the adjusting method of the application;

[0025] Figure 2 The structure schematic view of the superheating device in the embodiment of the application;

[0026] Figure 3 The structure schematic view of the jet flow type mixer in the embodiment of the application;

[0027] Figure 4 The backflow valve opening operating condition curve in the embodiment of the application.

[0028] Labeling components: 101-rotary vapor compressor, 102-jet mixer, 103-drive motor, 104-frequency converter; 105-flow meter; 201-backflow regulating valve; 202-backflow cut-off valve; 203-compressor bypass valve; 204-steam supply regulating valve; 301-low-quality steam temperature gauge; 302-steam supply temperature gauge. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0030] Example 1

[0031] A superheated steam flow and temperature regulating method, by frequency conversion drive system control to adjust the frequency of the rotary vapor compressor, by backflow temperature rise regulating bypass control to adjust the outlet flow of the rotary vapor compressor, set the target flow Qm and target temperature Tm of the rotary vapor compressor 101 outlet regulation, and set the amplitude Δf of the frequency f of the frequency conversion drive system and the regulating amplitude ΔK of the opening K of the backflow temperature rise regulating bypass, compare the target flow Qm and target temperature Tm with the current running outlet flow Qo and outlet temperature To, there are four kinds of comparison results: (1) Qm>Qo, Tm<To; (2) Qm<Qo, Tm<To; (3) Qm>Qo, Tm>To; (4) Qm<Qo, Tm>To, according to the four cases, different regulating actions are taken respectively: Figure 1

[0032] (1) Qm>Qo, Tm<To, at this time the outlet flow does not reach the target value, but the outlet temperature exceeds the target value, since the compressor characteristic is that if the backflow regulating valve 201 is not open, the outlet temperature will not exceed the target value, in this case, the backflow regulating valve 201 opening is too large, the opening of the backflow temperature rise regulating bypass is reduced, the opening K is reduced by ΔK;

[0033] (2) Qm<Qo, Tm<To, at this time the outlet flow exceeds the target value, and the outlet temperature also exceeds the target value, in this case, it is indicated that the frequency of the drive motor 103 and the opening of the backflow regulating valve 201 are too large, at this time the opening of the backflow temperature rise regulating bypass is reduced, the opening K is reduced by ΔK, and the frequency f of the frequency conversion drive system is reduced, the frequency is reduced by Δf;

[0034] ​(3) Qm>Qo, Tm>To, at this time the outlet flow is less than the target value, the outlet temperature is less than the target value, in this case, the frequency of the driving motor 103 and the opening of the backflow regulating valve 201 are not in place, at this time, the opening of the backflow temperature rise regulating bypass is increased, the opening K is increased by ΔK, and the frequency f of the variable frequency drive system is increased by Δf;

[0035] (4) Qm<Qo, Tm>To, at this time the outlet flow exceeds the target value, but the outlet temperature does not reach the target value, in this case, the opening of the backflow regulating valve 201 is not enough, at this time, the opening of the backflow temperature rise regulating bypass is increased, the opening K is increased by ΔK.

[0036] After the above adjustment action, the outlet flow Qo and the outlet temperature To will stabilize to a new operating state. By comparing the target flow Qm and the target temperature Tm, the comparison difference ΔQ and ΔT are obtained. If ΔQ and ΔT are within the allowable deviation range, the adjustment process is ended. If ΔQ and ΔT exceed the allowable target range, the outlet flow Qo and the outlet temperature To are returned to compare with the target flow and the target temperature, and the adjustment action of (1)-(4) above is performed according to the comparison result. The above adjustment process is repeated many times until the outlet flow and the outlet temperature reach the target value within the allowable deviation range.

[0037] The speed and accuracy of the adjustment can be changed by adjusting the amplitude Δf of the frequency f of the driving motor 103 and the amplitude ΔK of the opening of the backflow regulating valve 201. At the same time, the size of the difference ΔQ and ΔT set value also determines the size of the adjustment dead zone, which will affect the stability of the adjustment.

[0038] To achieve the dual adjustment target of temperature and flow, as shown in FIG. 2, the outlet flow Qo and the outlet temperature To are compared with the target flow Qm and the target temperature Tm, and the comparison difference ΔQ and ΔT are obtained. Figure 3 At the same outlet flow (and stable outlet pressure), increasing the frequency of the driving motor 103 and the opening of the backflow regulating valve 201 can achieve the increase of the outlet temperature. As shown in FIG. 3, the outlet flow Qo and the outlet temperature To are compared with the target flow Qm and the target temperature Tm, and the comparison difference ΔQ and ΔT are obtained. Figure 4 There are three working points 1, 2 and 3, at the same outlet flow, corresponding to different outlet temperatures, respectively, the backflow opening is 0%, the backflow opening is 50%, the backflow opening is 100%, and the output power of the variable frequency motor is also changing. Using the above adjustment method, the automatic control and adjustment of the outlet flow and temperature of the present application can be realized, according to different operating conditions, the speed and frequency of the variable frequency drive system are changed to change the speed of the rotary steam engine, and the opening of the backflow temperature rise regulating bypass is changed, so as to realize the flexible adjustment of the outlet flow and temperature of the rotary steam compressor 101, improve the temperature and flow control performance, realize the continuous adjustment of the temperature rise under different flow, and improve the temperature rise amplitude of the steam, which can realize the wide flow and large temperature rise variable working condition operation according to the operating condition requirements.

[0039] Example 2

[0040] like Figure 2 As shown, a steam superheating device for the above-mentioned regulation method includes a rotary steam compressor 101 and a swirl flow mixer 102, the low-pressure side of the swirl flow mixer 102 is connected to the low-quality steam through the steam supply pipeline, and the high-pressure side is connected to the return temperature rise regulation bypass. The outlet of the swirl flow mixer 102 is connected to the inlet of the rotary steam compressor 101. The low-quality steam enters the rotary steam compressor 101 through the swirl flow mixer 102 for quality improvement and then passes through the steam supply pipeline to the heat user. The other path enters the high-pressure side inlet of the swirl flow mixer 102 through the return temperature rise regulation bypass. The rotary steam compressor 101 is connected to a variable frequency drive system.

[0041] Low-quality steam enters the swirl flow mixer 102 through the low-pressure side, is mixed with the high-temperature and high-pressure steam from the rotary steam compressor 101 inside, and then enters the rotary steam compressor, which can achieve instant heating of the low-quality steam. After quality improvement, it is supplied to the heat user through the steam supply pipeline, with fast startup and no need for long-term preheating. By changing the speed and frequency of the rotary steam engine through the variable frequency drive system and adjusting the opening of the bypass according to the reflux temperature rise, continuous adjustment of the temperature rise can be achieved at different flow rates, and at the same time, the temperature rise amplitude of the steam is increased. According to the operating conditions, variable operating conditions with wide flow and large temperature rise can be achieved, and it is not limited by the voltage level and can be used for various voltage levels.

[0042] As a preferred embodiment, the reflux temperature rise regulating bypass is arranged between the outlet of the rotary steam compressor 101 and the inlet of the high-pressure side of the swirl flow mixer 102, and includes a reflux isolation valve 202 and a reflux regulating valve 201 arranged in series through pipelines. The steam supply pipeline to the heat user is provided with a steam supply regulating valve 204, a flow meter 105 and a steam supply thermometer 302, and the steam supply pipeline for low-quality steam is provided with a low-quality steam thermometer 301. The flow meter 105 adopts an orifice plate type, a nozzle type or a vortex type flow meter 105. The rotary steam compressor 101 can adopt a Roots type, a centrifugal type or a screw type (single or twin screw) steam compressor according to the design of the flow rate.

[0043] As a preferred embodiment, a compressor bypass is provided between the inlet and outlet of the rotary steam compressor 101, and a compressor bypass valve 203 is provided on the compressor bypass. By providing the compressor bypass, the steam flow rate at the compressor inlet can be adjusted to ensure that it is not lower than the minimum safe flow rate.

[0044] As a preferred embodiment, Figure 3As shown, the mixing element is arranged before the outlet of the rotational jet flow mixer 102. Wherein, N1 is the low pressure side inlet, N2 is the high pressure side inlet, and N3 is the outlet. The rotational jet flow mixer 102 is arranged with the mixing element before the outlet, so that the low quality steam and the high temperature and high pressure steam at the outlet of the rotary compressor are mixed uniformly in the mixer. The use of the rotational jet flow mixer 102 can not only ensure the uniform mixing of the steam, but also can use the residual pressure of the backflow steam to mix and preheat the low quality steam again, so as to avoid energy waste and save energy.

[0045] As a preferred embodiment, as shown in Figure 1 As shown, the variable frequency drive system comprises a driving motor 103 for driving the rotary steam compressor 101 and a frequency converter 104 for adjusting the speed and power of the rotary steam compressor 101. The driving motor 103 is configured as a high pressure or low pressure driving motor 103 according to the power requirement.

[0046] The present application provides an electric overheat system which can be used in various industrial industries. By being equipped with a backflow temperature rise adjusting bypass on the rotary steam compressor 101 and cooperating with the variable frequency drive system for adjustment, and by formulating a reliable adjustment mode, full working condition automatic adjustment is realized. The system has the characteristics of instantaneous heating, wide load adaptability and flexible automatic adjustment. The device is not limited by the access voltage level and can adapt to various different access voltage conditions and meet the requirements of various voltage levels. It can be accessed and used at 0.4kV-20kV, solving the shortcomings of the resistance type overheat device, such as large size, heating lag and inability to adapt to high voltage power connection. The device has fast starting speed and can instantly heat the steam to the required temperature without thermal hysteresis. By cooperating with the variable frequency drive system of the compressor and the backflow temperature rise bypass adjustment, the steam flow can be flexibly adjusted under the premise of meeting the steam supply temperature, so as to meet the steam supply demand of the heat user under variable working conditions. At the same time, the device adopts the rotational jet flow mixer 102, which can recover the outlet pressure and realize the effect of energy saving and consumption reduction.

[0047] Example 3

[0048] In order to verify the adjustment effect, a test was conducted in a steam supply unit of the present application, and the specific parameters are as follows: steam flow 30T / h, compressed from 800KpaA200℃ to 1200KPaA300℃. The total pressure ratio is 1.5, the compressor pressure ratio is low, and single stage compression is sufficient. At the same time, due to the temperature requirement at the outlet, a higher overheat degree is required, and the backflow needs to be increased to increase the overheat. The theoretical temperature rise of compression is 70℃. If the outlet needs to be increased by 100℃, the inlet temperature needs to be increased to 230℃ by backflow, and the backflow amount is 22T / h, that is, the actual compression amount of the compressor is 52T / h. The compressor is designed as a single stage booster compressor. The detailed parameter calculation is as follows:

[0049] 55000 kg / Hr water vapor compressor basic technical parameters:

[0050] Medium = water vapor

[0051] Gas constant [J / kg.k] = 461.52

[0052] Inlet mass flow rate [kg / Hr] = 52000

[0053] Inlet gas volume flow rate [M^3 / s] = 14.3

[0054] Inlet gas pressure [kPa, A] = 800

[0055] Inlet gas temperature [℃] = 230

[0056] Exhaust gas pressure [kPa, A] = 1260

[0057] Exhaust gas temperature [℃] = 304

[0058] Shaft power [kw] = 1750

[0059] Parameter required pressure ratio = 1.5

[0060] Return flow valve opening K, % 0％ 30％ 60％ 100％ Frequency of drive motor f, % 33 37 41 50 Outlet flow, t / h 30 30 30 30 Outlet temperature, °C 270 282.4 291.3 304

[0061] Through the design of the backflow valve, the temperature raising capacity of the compressor is increased from 70℃ to 104℃ under the outlet flow requirement of 30t / h, and if the backflow amount is designed to be larger, the temperature raising range will also be larger.

[0062] In summary, the low-quality steam enters the spiral jet mixer 102 through the low-pressure side, mixes with the high-temperature and high-pressure steam from the rotary steam compressor 101 inside, and then enters the rotary steam compressor, which can realize the instantaneous heating of the low-quality steam. After upgrading, it is supplied to the heat user through the steam supply pipeline, which starts quickly and does not need long preheating. According to different operating conditions, the speed and frequency of the rotary steam machine are changed through the frequency drive system, and the opening of the bypass is adjusted through the backflow temperature rise, so as to realize the flexible adjustment of the flow and temperature of the rotary steam compressor 101 outlet, improve the temperature and flow control performance, and realize continuous adjustment of the temperature rise under different flow rates. At the same time, the temperature rise range of the steam is improved, and the wide-flow and large-temperature-rise variable operating condition can be realized according to the operating condition requirements, and is not limited by the voltage level, which can be used for various voltage levels and is suitable for power plant heating technology field.

[0063] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the technical solutions described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalent ones. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for regulating superheated steam flow and temperature, characterized in that: Adjust the frequency of the rotary steam compressor through the variable frequency drive system control, adjust the outlet flow of the rotary steam compressor through the reflux temperature rise regulation bypass control, set the target flow Qm and target temperature Tm of the rotary steam compressor outlet regulation, and set the amplitude of the frequency f of the variable frequency drive system at the same time The adjustment amplitude of the bypass opening K is adjusted by the return temperature rise. , compare the target flow rate Qm and target temperature Tm with the current outlet flow rate Qo and outlet temperature To, there will be four comparison results: (1) Qm>Qo,Tm <To;(2) Qm<Qo, Tm<To;(3) )Qm> Qo, Tm>To;(4))Qm<Qo, Tm> To, take different adjustment actions for 4 situations: (1) When Qm > Qo and Tm < To, reduce the opening of the bypass for regulating the temperature rise of the return flow and decrease the opening K. ; (2) When Qm < Qo and Tm < To, reduce the opening degree of the bypass for regulating the temperature rise of the return flow, and decrease its opening degree K , and at the same time, reduce the frequency f of the variable frequency drive system ; (3) Qm>Qo, Tm>To, increase the return temperature rise to adjust the bypass opening, and increase its opening K , while increasing the frequency f of the variable frequency drive system, increasing its frequency ; (4) Qm<Qo, Tm> To, increase the opening of the return temperature rise regulating bypass, increase its opening K .

2. A method for regulating superheated steam flow and temperature according to claim 1, characterized in that: The inlet of the rotary steam compressor is connected to the outlet of the jet mixer. The low-pressure side of the jet mixer is connected to the low-quality steam through the steam supply pipeline, and the high-pressure side is connected to the return temperature rise regulation bypass. The low-quality steam enters the rotary steam compressor through the jet mixer for quality improvement and then passes through the steam supply pipeline to the heat user. The other path enters the high-pressure side inlet of the jet mixer through the return temperature rise regulation bypass. The rotary steam compressor is connected to a variable frequency drive system.

3. The method for regulating superheated steam flow and temperature according to claim 1, wherein: The reflux temperature rise regulating bypass is arranged between the outlet of the rotary steam compressor and the inlet of the high-pressure side of the jet mixer, and includes a reflux isolation valve and a reflux regulating valve arranged in series through pipelines.

4. The method for regulating superheated steam flow and temperature according to claim 2, wherein: The steam supply pipeline to the heat user is provided with a steam supply regulating valve, a flow meter and a steam supply thermometer, and the steam supply pipeline of the low-quality steam is provided with a low-quality steam thermometer.

5. The method for regulating superheated steam flow and temperature according to claim 4, characterized in that: The flow meter is an orifice plate type, a nozzle type or a vortex type flow meter.

6. The method for regulating superheated steam flow and temperature according to claim 1, characterized in that: A compressor bypass is provided between the inlet and outlet of the rotary steam compressor, and a compressor bypass valve is provided on the compressor bypass.

7. The method for regulating superheated steam flow and temperature according to claim 1, characterized in that: The rotary steam compressor is designed according to the flow rate and adopts a roots type, centrifugal type or screw type steam compressor.

8. The method for regulating superheated steam flow and temperature according to claim 3, characterized in that: A mixing element is provided in front of the outlet of the jet mixer.

9. The method for regulating superheated steam flow and temperature according to claim 1, characterized in that: The variable frequency drive system includes a drive motor for driving a rotary steam compressor and a frequency converter for adjusting the speed and power of the rotary steam compressor. The drive motor is configured as a high-voltage or low-voltage drive motor according to power requirements.

Images