System for estimating total dissolved solid concentration in boiler water and steam boiler

Abstract

There is described a system (12) for estimating a total dissolved solids (TDS) concentration in boiler water, comprising: a sensor (14) having a transmitter configured to transmit a radio frequency or microwave signal into the boiler water and a receiver configured to receive a reflected signal from a reflection of the radio frequency or microwave signal by the boiler water; and an analysis module (16) configured to determine a conductivity value of the boiler water based on the reflected signal and to determine a TDS concentration of the boiler water based on the conductivity. A steam boiler including the system is also described.

Description

Technical Field

[0001] This disclosure relates to a system for estimating the total dissolved solids concentration in boiler water and a steam boiler including such a system. Background Technology

[0002] As the boiler generates steam, any impurities in the boiler feedwater that are not evaporated by the steam will accumulate in the boiler water.

[0003] As the total dissolved solids (TDS) become more concentrated, steam bubbles tend to become more stable and do not break when they reach the boiler water surface. At a point (depending on boiler pressure, size, and steam load), most of the steam space in the boiler becomes filled with bubbles, and the foam is carried into the steam header.

[0004] This is undesirable, not only because the steam leaves the boiler too wet, but also because it contains boiler water with a high content of dissolved or potentially suspended solids. These solids can contaminate control valves, heat exchangers, and steam traps.

[0005] TDS (Total Dissolved Solids) comes from dissolved organic and inorganic substances in boiler feedwater. In particular, common salt components in boiler feedwater include calcium, sodium, chloride, potassium, phosphate, and nitrate.

[0006] To avoid performance and safety issues in boilers, it is necessary to measure, monitor, and control the TDS concentration in boiler water. Utility Model Content

[0007] According to one aspect, a system for estimating the total dissolved solids (TDS) concentration in boiler water is provided, the system comprising: a sensor having a transmitter and a receiver, the transmitter being configured to transmit a radio frequency or microwave signal into the boiler water, and the receiver being configured to receive a reflected signal from the boiler water reflecting the radio frequency or microwave signal; and an analysis module configured to determine a conductivity value of the boiler water based on the reflected signal, and to determine the TDS concentration of the boiler water based on the conductivity.

[0008] The analysis module can also be configured to determine the reflection coefficient based on the reflected signal and the conductivity value based on the reflection coefficient.

[0009] The system may also include a control module configured to determine whether the TDS concentration exceeds a threshold and to take measures if the TDS concentration does exceed the threshold.

[0010] If the TDS concentration exceeds the threshold, the control module can output an alarm to the operator.

[0011] If the TDS concentration exceeds the threshold, the control module can open the sewage control valve to reduce the TDS concentration.

[0012] The sensor can be an open coaxial probe. The probe can be a high-pressure, high-temperature probe.

[0013] The analysis module may include a vector network analyzer.

[0014] According to another aspect, a steam boiler including the above-described system is provided.

[0015] According to another aspect, a method for estimating the total dissolved solids (TDS) concentration in boiler water is provided, the method comprising: transmitting a radio frequency or microwave signal into the boiler water; receiving a reflected signal from the boiler water reflecting the radio frequency or microwave signal; determining a conductivity value of the boiler water based on the reflected signal; and determining the TDS concentration of the boiler water based on the conductivity.

[0016] The method may further include: determining the reflection coefficient based on the reflected signal; wherein the conductivity value is determined based on the reflection coefficient.

[0017] Sensor probes can be used to send and receive radio frequency or microwave signals.

[0018] The sensor probe can be an open coaxial probe. Alternatively, a coaxial transmission line or resonant cavity measurement system that can be connected to a drain line can be used to transmit and receive radio frequency or microwave signals.

[0019] The method may also include: determining whether the TDS concentration exceeds a threshold; and if the TDS concentration does exceed the threshold, taking measures.

[0020] This measure may include providing alerts to operators.

[0021] This measure may include opening the drain control valve to reduce TDS concentration. Attached Figure Description

[0022] To better understand the invention and to more clearly show how to implement it, reference will now be made to the accompanying drawings by way of example, wherein:

[0023] Figure 1 This is a schematic diagram of a steam boiler apparatus having a system according to an embodiment of the present invention;

[0024] Figure 2 (a) is a front view of the probe of the system, and Figure 2 (b) is a cross-sectional view of the probe; and

[0025] Figure 3 This is a flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0026] Figure 1 A schematic diagram of a steam boiler assembly 2 is shown. The steam boiler assembly 2 includes a steam boiler 4. The steam boiler 4 is connected to a feedwater line 6 and a steam main 8. Water 10 is pumped from a feedwater tank to the boiler 4 by a feedwater pump (not shown). The water 10 is then heated within the boiler 4 to form steam, which is released via the steam main 8 and delivered to the point of use.

[0027] The steam boiler 4 is equipped with a TDS monitoring system 12 according to an embodiment of the present invention. The system 12 includes a sensor probe 14 connected to an analysis module 16. The output from the analysis module 16 is provided to a control module 18, which can be used to control the blowdown valve 20 or take other measures.

[0028] like Figure 2 (a) and Figure 2 As shown in (b), the sensor probe 14 is an open coaxial probe, which includes an inner conductor 22 and an outer conductor 24 arranged concentrically and separated from each other by a dielectric material 26. The dielectric material 26 is disposed between the inner conductor 22 and the outer conductor 24 so that the inner conductor 22 and the outer conductor 24 are electrically isolated from each other.

[0029] like Figure 2 As shown in (b), the sensor probe 14 is inserted through an opening formed in the wall 28 of the steam boiler 4, such that the sensor probe 14 is immersed in the boiler water 10. The sensor probe 14 may be a high-pressure-high-temperature probe capable of withstanding the conditions of the steam boiler 4. The outer conductor 24 may form a flange 28, which abuts against the inner surface of the wall 28.

[0030] As previously described, sensor probe 14 is connected to analysis module 16 via probe connection cable 17. In this embodiment, analysis module 16 includes a vector network analyzer (VNA). The VNA includes a signal source that generates radio frequency (RF) or microwave signals, which are transmitted to sensor probe 14.

[0031] An RF or microwave signal generates an electromagnetic field between the inner conductor 22 and the outer conductor 24. This electromagnetic field is emitted into the boiler water 10 and reflected by the boiler water 10. Figure 3 The VNA also includes a receiver, which, in step S4, receives the reflected signal from sensor probe 14 after being reflected by boiler water 10.

[0032] In step S6, the analysis module 16 determines the conductivity value of the boiler water 10. This is determined by calculating the reflection coefficient based on the ratio of the amplitude of the reflected signal to the amplitude of the transmitted signal (i.e., the incident signal). It has been found that the amplitude of the reflected signal depends on the conductivity of the boiler water 10. Accordingly, the analysis module 16 is then able to determine the conductivity of the boiler water 10 from the reflection coefficient. Then, in step S10, the analysis module 16 determines the TDS concentration from the conductivity.

[0033] The correlations between reflectance and conductivity, as well as between conductivity and TDS concentration, can be determined primarily empirically. This method can be repeated using signals of different frequencies to improve accuracy.

[0034] As previously stated, the output from the analysis module 16 can be provided to the control module 18, which can take action in response to the current TDS concentration. Specifically, the control module 18 can open the drain valve 20 to release water 10 from the boiler 4 and replace it with fresh feedwater, thereby reducing the TDS concentration of the boiler water in the boiler 4. This action can be taken when the current TDS concentration exceeds a threshold.

[0035] In other embodiments, control module 18 may provide alarms, such as audible or visual alarms, as prompts to human operators to take action to reduce TDS concentration. For example, an operator may manually open drain valve 20. In other embodiments, the output from analysis module 16 may simply be displayed to the operator to allow them to monitor and control TDS concentration. It is understood that analysis module 16 and control module 18 may be embodied in a single unit (e.g., a processor) and distinguished only by their functionality.

[0036] In other examples, coaxial transmission lines or resonant cavity measurement systems that can be connected to drain lines can be used to transmit and receive RF or microwave signals.

[0037] The present invention is not limited to the embodiments described herein and can be modified or adjusted without departing from the scope of the invention.

Claims

1. A system for estimating the concentration of total dissolved solids (TDS) in boiler water, the system comprising: A sensor having a transmitter and a receiver, the transmitter being configured to transmit a radio frequency or microwave signal into the boiler water, and the receiver being configured to receive a reflected signal from the boiler water reflecting the radio frequency or microwave signal. as well as An analysis module is configured to determine the conductivity value of the boiler water based on the reflected signal, and to determine the total dissolved solids concentration of the boiler water based on the conductivity value.

2. The system according to claim 1, wherein, The analysis module is also configured to determine the reflection coefficient based on the reflected signal and to determine the conductivity value based on the reflection coefficient.

3. The system according to claim 1 or 2 further includes a control module configured to determine whether the total dissolved solids concentration exceeds a threshold, and to take measures if the total dissolved solids concentration does exceed the threshold.

4. The system according to claim 3, wherein, If the total dissolved solids concentration exceeds the threshold, the control module outputs an alarm to the operator.

5. The system according to claim 3, wherein, If the total dissolved solids concentration exceeds the threshold, the control module opens the sewage control valve to reduce the total dissolved solids concentration.

6. The system according to claim 1 or 2, wherein, The sensor is an open coaxial probe.

7. The system according to claim 1 or 2, wherein, The analysis module includes a vector network analyzer.

8. A steam boiler comprising the system according to any one of claims 1 to 7.

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