WO2013175664A1

WO2013175664A1 - Steam pressure measurement device for boiler and steam amount measurement device for boiler

Info

Publication number: WO2013175664A1
Application number: PCT/JP2012/081806
Authority: WO
Inventors: 記章長井; 善範金塚; 田中　收
Original assignee: 三浦工業株式会社
Priority date: 2012-05-23
Filing date: 2012-12-07
Publication date: 2013-11-28
Also published as: JP2013242120A

Abstract

The purpose of the present invention is to easily measure steam pressure, without attaching a pressure measurement means that directly detects steam pressure. A boiler steam pressure measurement device that measures the saturated vapor pressure of a steam boiler (2) and comprises: temperature sensors (5A, 5B) mounted in contact with an outer surface (4A) of a section (4) in a phase equilibrium state with steam flow paths (3A, 3B) in the steam boiler (2); a heat-insulating material (6) that covers the temperature sensors (5A, 5B) such that the heat discharge amount from the attachment section of the temperature sensors (5A, 5B) is a negligible value; and a controller (7) that calculates the saturated vapor pressure inside the steam flow paths (3A, 3B) on the basis of the measurement values for the temperature sensors (5A, 5B).

Description

Boiler steam pressure measuring device and boiler steam amount measuring device

This invention relates to a steam pressure measuring device for a boiler and a steam amount measuring device for a boiler that measure the steam pressure without using a pressure measuring means that directly measures the pressure. This application claims priority based on Japanese Patent Application No. 2012-117157 for which it applied to Japan on May 23, 2012, and uses the content here.

Conventionally, a simple steam amount measuring method for measuring a steam amount without using a steam flow meter is known in Patent Document 1 and Patent Document 2. However, in these conventional apparatuses, it is necessary to measure the steam pressure of the boiler by the pressure measuring means that directly measures the pressure.

Japanese Patent No. 2737753 JP 2010-139207 A

In these conventional devices, in order to measure the steam pressure of the existing steam boiler, a hole must be made in the steam pipe and a pressure measuring means must be attached. In order to install the pressure measuring means, the operation of the steam boiler must be stopped.

The problem to be solved by the present invention is to easily measure the steam pressure without attaching a pressure measuring means for directly detecting the steam pressure.

This invention was made in order to solve the said subject, The invention of Claim 1 is a steam pressure measuring device of the boiler which measures the saturated steam pressure of a steam boiler, Comprising: Steam flow of the said steam boiler A temperature sensor that is mounted in contact with an outer surface of a portion in a phase equilibrium state of the road and measures the outer surface temperature, and the temperature sensor is set so that the amount of heat released from the mounting portion of the temperature sensor can be ignored. And a controller for calculating a saturated steam pressure in the steam channel based on a measured value of the temperature sensor.

According to the first aspect of the present invention, it is possible to easily measure the saturated steam pressure without attaching a pressure measuring means.

The invention according to claim 2 comprises the vapor pressure measuring device according to claim 1, and continuously calculates the steam amount X without using a steam flow meter using the saturated steam pressure in the steam flow path. It features a steam volume measuring device.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is possible to easily measure the amount of steam without using a steam flow meter.

According to the present invention, it is possible to easily measure the steam pressure without attaching a pressure measuring means for directly detecting the steam pressure.

It is a schematic block diagram of embodiment of the vapor | steam amount measuring apparatus which implemented this invention. It is sectional drawing which illustrates typically the attachment state of the temperature sensor of the embodiment. It is a flowchart figure explaining the control program of the embodiment. It is a flowchart figure explaining the other control program of the embodiment.

An embodiment of the vapor amount measuring apparatus 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of the embodiment, FIG. 2 is a flowchart for explaining a control program of the embodiment, and FIG. 3 is a flowchart for explaining another control program of the embodiment. is there.

<Configuration of Embodiment>
The steam amount measuring device 1 of this embodiment is a device that measures a steam amount X (steam flow rate of the steam outflow passage 3A as a steam passage) of a steam boiler (hereinafter simply referred to as a boiler) 2. The steam amount measuring device 1 of the present invention is a steam pressure gauge side device 1A that calculates a saturated steam pressure (hereinafter referred to as a steam pressure unless otherwise specified) using a temperature sensor without using a pressure measuring means. There is a feature in including. Although the steam amount measuring device 1 calculates the steam amount X based on the steam pressure measured by the steam pressure gauge side device 1A, the present invention is not characterized by the configuration for calculating the steam amount X. Therefore, the calculation configuration of the steam amount X of the present invention is not limited to the calculation configuration of the steam amount X described below.

The steam pressure measuring device 1A is mounted in close contact with the outer surface (which can be referred to as an outer surface) 4A of the phase equilibrium portion 4 in the phase equilibrium state of the steam outlet passage 3A of the boiler 2, and the temperature (outer surface) of the outer surface 4A. The temperature sensor 5 for measuring the temperature (Two) and the temperature sensor 5 so that the heat radiation amount Qloss from the mounting portion of the temperature sensor 5 (including the first temperature sensor 5A and the second temperature sensor 5B described later) is negligible. And a controller 7 for calculating the steam pressure in the steam outflow passage 3A estimated based on the measured value of the temperature sensor 5. As shown in FIGS. 1 and 2, the first temperature sensor 5 A and the second temperature sensor 5 B are each about 10 times the pipe thickness on the outer surface of the steam outlet path 3 A and the steam outlet path 3 B (or the steam header 21). Along with it, the tip temperature sensing part is closely attached.

Here, “being in a phase equilibrium state” means that changes in pressure, flow velocity, etc. are slow and pressure and temperature are in a thermodynamic equilibrium state. The relation between the pressure and temperature in the phase equilibrium state of water and steam is presented with a high-precision approximate expression based on the steam table data. However, in the method of indirectly obtaining the true saturated steam temperature Tvs from the measured tube wall temperature according to the present invention, as a result, the following 1) to 4) greatly affect the saturated steam pressure calculation and the steam flow rate calculation.
1) Temperature drop due to heat radiation of temperature measurement unit 2) Error component of measurement system (sensor body, sensor mounting method, sensor temperature measurement device electrical accuracy (amplifier circuit, resolution, zero point compensation, etc.) 3) Intervening object ( Temperature response delay due to pipe wall etc. (especially when finding differential pressure from temperature difference of saturation temperature between two points)
4) Change in the amount of generated steam

For example, the portion 4 of the vertical steam pipe 10 on the outlet side of the drum 9 connected to the outlet side of the can body 8 of the boiler 2 or the outlet side of the steam header 21 described later can be used as the portion 4 where the phase equilibrium is easily maintained. The steam pipe 10 (or the steam header 21).

Regarding the error influence of 1), the “value that can ignore the amount of heat released from the temperature sensor mounting portion” is determined by the relative size of the error component described above. Therefore, when all other error factors are eliminated, it can be said that it can be suppressed to a sufficient value by heat insulation as described later. However, when similar error components are present, consideration must be given to reducing those error components to 1/2 and 1/3.

(2) For the accuracy of the measurement system, an appropriate mounting method, a temperature sensor such as a thermocouple, or a high-precision temperature measurement device may be selected.

In order to reduce the influence of temperature measurement delay due to inclusions in 3), the boiler 2 is preferably a boiler having a large amount of water, for example, a large water tube / furnace smoke tube boiler. The reason why a boiler with a large amount of water is preferred is as follows. The thermal time constant of a steam pipe is generally about several seconds, so a boiler with a large amount of water in the boiler has a thermal time constant of several minutes or more, but this is not a problem, but a small once-through boiler has a few tens of seconds. The thermal time constant is small, which is about the same as the delay in tube wall measurement.

Regarding the change in the amount of steam generated in 4), in the ON-OFF, which is not proportional combustion in the combustion control, in the three-position control boiler, the steam generation amount changes sharply, and the steam-water flows (measurement unit) ) Thermal non-equilibrium state, that is, the vapor phase increases or decreases by several degrees C. depending on the case. Therefore, a boiler with less ON-OFF fluctuation such as proportional combustion is desirable.

Next, “a value at which the amount of heat released from the mounting portion of the temperature sensor 5 can be ignored” will be further described. Although it is desirable that the heat dissipation amount Qloss is as close to zero as possible, it cannot actually be zero. Hereinafter, it will be described that the heat dissipation amount Qloss can be made a negligible value.

The heat dissipation amount Qloss can be calculated as follows.
A difference (Tvs−Ta) between the pipe steam temperature Tvs and the outside air temperature Ta is defined as a temperature difference ΔT. The reciprocal of the sum of the total heat resistance of the outside air and heat insulation surface, the heat resistance of the insulation, the heat conduction heat resistance of the steam pipe (steel pipe) 10, the condensation / flow heat resistance of the inner surface of the air pipe, The rate is KW / m ² K. When the heat insulating material outer surface Som ² is a reference surface, Qloss is calculated by the following equation 1.
Qloss = K × So × ΔT ... Equation 1

Now, the diameter of the steam pipe 10 is large, and the difference between the outer diameter of the heat insulating material 6 (the diameter of the heat insulating material 6 wound in a cylindrical shape outside the steam pipe 10) and the diameter of the steam pipe 10 is the diameter of the steam pipe 10. It is assumed that the value divided by is about several percent. The heat resistance between the outer surface of the heat insulating material 6 and the outside air temperature is 1 / ha, the heat resistance of the heat insulating material 6 is 1 / (k / δ) ins, and the heat resistance of the steel pipe 10 is similarly 1 / (k / δ). ) If tube is set and the thermal resistance of the inner surface of the steam pipe 10 is 1 / hc, the total thermal resistance 1 / K is the sum thereof, so that the following equation 2 is obtained.
1 / K = 1 / ha + (δ / k) ins + (δ / k) tube + 1 / hc ・・・ Equation 2

From Equation 1 and Equation 2,
Expressed in terms of heat dissipation Qloss due to the difference ΔT between the steam temperature Tvs in the pipe and the outside air temperature Ta,
Qloss / So = K × ΔT ... Equation 3
Also, when expressed in terms of heat dissipation Qloss due to the difference between the steam temperature Tvs in the tube and the outer surface temperature Two of the tube,
Qloss / So = 1 / {1 / (k / δ) tube + 1 / hc} × (Tvs−Two) Equation 4

In order to make the temperature difference (Tvs-Two) between the tube outer surface temperature and the tube steam temperature to be measured zero, we want to set the heat dissipation to zero from the relationship of Equation 4, but since it is actually a finite value,
From Equation 3 and Equation 4,
(Tvs−Two) = K × {1 / (k / δ) tube + 1 / hc} × ΔT Equation 5
As can be seen from Equation 5, the right side is made as small as possible.

With proper insulation construction, K = 1 W / m ² K, steam pipe 10 k = 53 W / m ² K, 100A steel pipe thickness δ = 0.0045 m, and pipe hc = 5800 W / m ² Since it is about K,
K × {1 / (k / δ) tube + 1 / hc} ≈0.0003
Therefore, Tvs-Two ＝ ΔT × 0.0003 ＝ 210 ℃ × 0.0003 ＝ 0.063 ℃ in a 2MPa high-pressure boiler operating in winter (outside air 5 ℃)
Therefore, the allowable value of the temperature difference (Tvs-Two) of the saturation temperature at one point is the saturation temperature corresponding to the pressure difference between the two points when the pressure difference is calculated from the temperature difference between the saturation temperatures of the two points. The accuracy for the difference of 1.5 to 3 ° C is 5% = 0.075 to 0.15 ° C or less. Note that the saturation temperature difference of 1.5 to 3 ° C is the estimated minimum value ΔP = 0.05 MPa for the steam pipe differential pressure (differential pressure between the boiler and the steam header) at the maximum flow rate when the load steam pressure is 0.5 MPa to 1.6 MPa. This is the temperature difference corresponding to the case.

In this way, if appropriate heat insulation is performed with the heat insulating material 6, Tvs≈Two and the heat dissipation Qloss can be ignored. In this embodiment, as shown in FIG. 2, the temperature measurement wall or the thickness of the tube 10 is reduced with respect to the first temperature sensor 5A (and the second temperature sensor 5B) in consideration of heat loss suppression in the tube axis direction. The heat insulation material 6 made of glass wool with a thickness of 50 mm or more is kept warm for a radius circle or tube length equivalent area of about 15 times or more. In the figure, only the first temperature sensor 5A is shown, but the second temperature sensor 5B is similarly insulated.

Next, a configuration for calculating the steam amount X by the steam amount measuring device 1 will be described. The steam amount measuring device 1 includes a differential pressure detecting means 11 that calculates a differential pressure ΔP based on the steam pressure measured by the steam pressure measuring device 1A, an original data measuring means 12, and a controller that controls the measurement of the steam amount X. 7.

The differential pressure detecting means 11 is separated from the first temperature sensor 5A and the first temperature sensor 5A for measuring the temperature (first temperature Two1) of the outer surface 4A (first detection position) of the phase equilibrium portion 4 of the steam pipe 10. A second temperature sensor 5B that measures the temperature (second temperature Two2) of the outer surface 4A at the position (second detection position), and the vapor pressure (first pressure P1) obtained from the first temperature Two1 and the first A differential pressure ΔP between the vapor pressure (second pressure P2) obtained from the two temperatures Two2 is measured.

The original data measuring means 12 is a measuring means for calculating the reference steam amount X0, and in this embodiment, the first temperature sensor 5A, the second temperature sensor 5B, and the exhaust gas flow velocity M in the exhaust gas passage 13 are measured. An exhaust gas velocity meter 14, an exhaust gas oxygen concentration meter 15 that measures the oxygen concentration in the exhaust gas, an exhaust gas thermometer 16 that measures the temperature of the exhaust gas, an air supply thermometer 17 that measures the supply air temperature, and a water supply temperature A feed water thermometer 18 to be measured is included. Of these measuring means, those already installed in the boiler 2 are used as needed without being newly provided.

The controller 7 inputs signals from the respective measuring instruments of the first temperature sensor 5A, the second temperature sensor 5B, and the original data measuring means 12, and measures the vapor amount measured based on a previously stored control procedure (control program). X is configured to be output to the display 19. An example of the control procedure is shown in FIGS.

The control procedure by the controller 7 includes a pressure loss coefficient calculation procedure shown in FIG. 3 and a steam amount calculation / output procedure (in other words, a steam amount measurement procedure) shown in FIG. The pressure loss coefficient calculation procedure corresponds to a calculation source data input step for inputting calculation source data (signal from each measuring instrument of the original data measuring means 12) and a differential pressure ΔP (first temperature Two1 by the first temperature sensor 5A). A differential pressure input step of inputting a first pressure P1 to be performed and a first pressure detection pressure P2 corresponding to the second temperature Two2 by the second temperature sensor 5B), and a reference steam amount X0 is obtained from the calculation source data. Calculate the pressure loss coefficient J from the difference between the reference steam amount calculation step and the pressure difference ΔP when the reference steam amount X0 is determined, and the steam amount X calculated based on the pressure loss calculation formula (6) below is equal to the reference steam amount X0. And a coefficient calculating step.
ΔP = J × X ² ÷ ρ ・・・・・・ Formula 6
Where ρ is the steam specific weight determined from P1

In addition, the steam amount calculation / output procedure is based on the pressure loss calculation formula (formula 6) from the pressure difference ΔP input in the differential pressure input step and the pressure loss coefficient J calculated in the coefficient calculation step. And a steam amount output step for outputting the calculated steam amount X to the display 19 as a measured value.

1 is a steam header for connecting

steam outflow passages

3B, 3B,... For distributing steam to a plurality of steam use loads (not shown), and reference numeral 23 is combustion to the burner 22. The reference numeral 24 is a fuel flow path to the burner 22, and the reference numeral 25 is a water supply path to the can body 8. Moreover, the code | symbol 26 in FIG. 2 is a normal heat insulating material which covers the steam pipe 10. FIG.

<Operation of Embodiment>
Next, the operation of the embodiment will be described with reference to the drawings. Now, it is assumed that the steam amount X of the existing boiler 2 is measured using the steam amount measuring device 1. First, in the operation stop state of the boiler 2, as shown in FIG. 1, the first temperature sensor 5A, the second temperature sensor 5B, the exhaust gas velocity meter 14, the exhaust gas oxygen concentration meter 15, the exhaust gas thermometer 16, the supply air thermometer 17 , A feed water thermometer 18 is attached. As shown in FIG. 2, the first temperature sensor 5 A and the second temperature sensor 5 B are attached in close contact with the outer surface 4 A of the steam pipe 10, and the outer surface is heat-insulated with the heat insulating material 6. In this state, the operation of the boiler 2 is started, and the start switch (not shown) of the steam amount measuring device 1 is turned on to start measurement.

(Calculation of pressure loss coefficient J)
First, calculation of the pressure loss coefficient J will be described. The calculation of the pressure loss coefficient J is performed when the pressure of the can body 8 is stable. Specifically, the measurer operating the steam amount measuring device 1 observes the output with an existing pressure gauge (not shown) in the boiler 2 and the pressure fluctuation range is ± 5% or less continuously for 5 minutes. The pressure loss coefficient J is calculated by turning on the coefficient calculation switch (not shown). Of course, the determination of stability and the operation of the coefficient calculation switch can be automatically performed.

As will be described with reference to FIG. 3, the controller 7 takes in signals from each measuring device of the original data measuring means 12 in step S 1 (hereinafter, step SN is simply referred to as SN). Next, in S2, the differential pressure ΔP is calculated and input. The differential pressure ΔP is calculated by converting into the saturated steam pressure, assuming that the detected temperatures of the first temperature sensor 5A and the second temperature sensor 5B are equal to the saturated steam temperature.

Next, in S3, the reference steam amount X0 is calculated by Equation 7 from the average value of the values sampled from the measurement data for the past 5 minutes of the original data measuring means 12. Here, the case of gaseous fuel is shown.
X0 = (η × HL × N) / (h1-h2) Equation 7
However, X0: Reference steam volume (kg / h), η: Boiler efficiency (%), HL: Lower fuel heating value (MJ / m ³ N), N: Fuel flow rate (m ³ N / h), h1: Saturation Steam enthalpy (MJ / kg), h2: Water supply enthalpy (MJ / kg)

The fuel flow rate N is calculated from the following equation 8.
N = Y1 / {G0 + Gw + (m−1) × A0}.
Y1: Standard exhaust gas flow rate (m ³ N / h),
(G0 + Gw + (m−1) × A0): Actual wet exhaust gas amount (m ³ N / m ³ N, fuel)
G0: Theoretical dry exhaust gas volume (m ³ N / m ³ N, fuel)
Qw: Water vapor generated by combustion and water vapor due to water in the fuel (m ³ N / kg)
(G0 + Gw): Theoretical exhaust gas volume (m ³ N / m ³ N, fuel)
A0: Theoretical air volume (m ³ N / m ³ N, fuel)
m: Air ratio

The exhaust gas standard flow rate Y1 is calculated from the following equation 9.
Y1 = Y2 × 273 / (273 + T1) Equation 9
Y2: Exhaust gas actual flow rate (m ³ / h), T1: Exhaust gas temperature (K) measured by the exhaust gas thermometer 16

The exhaust gas actual flow rate Y2 is calculated from the following equation 10.
Y2 = M x S x 3600 Equation 10
However, M: Exhaust gas flow velocity (m / s) measured by the exhaust gas velocity meter 14, S: Cross sectional area of the exhaust gas flow path (m ² )
Eventually, the reference steam amount X0 can be calculated from the exhaust gas flow velocity M obtained from the measurement signal from the exhaust gas velocity meter 14.

Next, in S4, the reference steam amount X0 calculated in S3 is equal to the steam amount X (determined by Equation 6) obtained from the differential pressure ΔP when the reference steam amount X0 is calculated, that is, X0 = X. The pressure loss coefficient J is calculated. Since values other than the pressure loss coefficient J are obtained, the pressure loss coefficient J can be calculated from X0 = X.

(Steam calculation / output)
Next, a vapor amount calculation / output procedure, that is, a vapor amount measurement procedure will be described. As will be described with reference to FIG. 4, in S5, the steam amount X is continuously calculated by substituting the pressure calculation coefficient J calculated in S4 and the differential pressure ΔP continuously measured in Equation 6 into S6. In S 6, the calculated vapor amount X is output to the display 19.

According to the above embodiment, the steam pressure gauge side device 1A can easily calculate the differential pressure ΔP using the detected temperatures of the first temperature sensor 5A and the second temperature sensor 5B. Further, even in a boiler 2 that does not include a fuel flow meter in the fuel flow path 20, the pressure loss coefficient J is simply calculated from the calculation source data of the differential pressure ΔP measured by the steam pressure gauge side device 1A and the reference steam amount X0. be able to. In addition, after calculating the pressure loss coefficient J, the steam amount X is calculated regardless of the heat input / output heat amount and fuel property value of the boiler. Therefore, even if the heat input / output heat amount and fuel property value of the boiler change, the steam amount X is relatively accurate. Can be calculated. This effect is particularly remarkable when coal, biofuel, or the like whose fuel properties are unstable is used as the fuel for the boiler, or when the control fluctuation of the boiler is large.

The present invention is not limited to the steam amount measuring apparatus 1 of the above embodiment, and various modifications can be made. For example, in a known steam quantity measuring apparatus that simply calculates the steam quantity X without using a steam flow meter and requires a steam pressure measurement by a steam pressure measuring means that directly measures the steam pressure, The vapor pressure can be calculated by the temperature sensor without using the pressure measuring means. As said well-known vapor | steam measuring device, the thing of patent document 2 can be mentioned, for example. The steam amount measuring device described in Patent Document 2 measures the total pressure and static pressure in the exhaust gas flow path 13 of the boiler 2, and measures the exhaust gas flow velocity in the exhaust gas flow path 13 from the difference between the total pressure and the static pressure. An exhaust gas velocity meter (not shown) using a Pitot tube and an exhaust gas thermometer 16 for measuring the temperature of combustion exhaust gas are provided, and the fuel usage of the boiler 2 is determined by the values measured by these measuring devices and the intrinsic values of the boiler 2. The vapor amount X is calculated by calculation and the fuel consumption amount calculated by calculation is used.

Further, a method for obtaining the reference steam amount X0 from the fuel flow rate N that is the calculation source data and obtaining the heat input amount Q from the obtained heat input amount Q is known from Patent Document 1 or the like. Therefore, as described in Patent Document 1, the steam amount measuring apparatus 1 of the above embodiment measures the fuel flow rate N with a fuel flow meter provided in the fuel supply path of the boiler, and calculates and measures the following equation. can do. In addition, the fuel of patent document 1 is a liquid fuel.
Heat input Q = Fuel flow rate N x Fuel specific gravity x Fuel lower heating value Reference steam quantity X0 = Heat input Q x Boiler efficiency ÷ Increase in enthalpy

The steam amount measuring apparatus 1 according to the above-described embodiment uses this to measure the maximum steam usage by the steam usage load of the boiler 2 and / or the trend measurement of the temporal variation of the steam usage. Can be used as

1 Steam volume measuring device 1A Steam pressure measuring device 2 Steam boiler (boiler)
3A, 3B Steam outflow path 4

Phase equilibrium part

5A, 5B Temperature sensor 6 Heat insulating material 7 Controller

Claims

A steam pressure measuring device for a boiler that measures a saturated steam pressure of a steam boiler,
A temperature sensor that is mounted in contact with an outer surface of a portion in a phase equilibrium state of the steam flow path of the steam boiler, and measures the outer surface temperature;
A heat insulating material that covers the temperature sensor so that the amount of heat released from the mounting portion of the temperature sensor can be ignored;
A steam pressure measuring device for a boiler, comprising: a controller that calculates a saturated steam pressure in the steam channel based on a measured value of the temperature sensor.
A steam amount of a boiler comprising the steam pressure measuring device according to claim 1, wherein the steam amount X is continuously calculated using a saturated steam pressure in the steam flow path without using a steam flow meter. Measuring device.