JP3843714B2 - Gas temperature control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas temperature control device for controlling a gas temperature in a process without enthalpy change.
[0002]
[Prior art]
In a plant that burns with gaseous fuel and uses the energy to operate equipment, it is necessary to maintain the fuel flow rate, fuel pressure, and fuel temperature at predetermined values in order to obtain a stable combustion state. It is a condition. For this reason, fuel lines are usually equipped with equipment for controlling these values. Among these, the pressure reducing equipment for controlling the fuel pressure to a predetermined value controls the gas flow rate by controlling the opening of the pressure reducing valve, and lowers the downstream pressure to maintain a constant value. is there.
[0003]
In general, when gas passes through the pressure reducing process, it undergoes adiabatic expansion, so that the temperature of the gas decreases after passing through the pressure reducing valve. In particular, when the pressure change after depressurization is large, this temperature decrease is also large. Therefore, in a plant where such a temperature decrease becomes a problem, the gas is preheated before passing through the pressure reducing valve. The gas temperature after depressurization is compensated, and the temperature is controlled to be a predetermined temperature after depressurization.
[0004]
FIG. 11 is a configuration diagram for explaining a conventional temperature control method.
[0005]
This control method will be described with reference to the drawings.
[0006]
The gaseous fuel 51 flowing through the fuel line is depressurized by a pressure reducing valve 52 via a heat exchanger 58 and then its temperature is measured by a thermometer 53. The temperature measurement value 54 is input to the temperature control device 55 and compared with the temperature set value 56. When the temperature measurement value 54 is higher than the temperature set value 56, the temperature control device 55 reduces the flow rate of the heating fluid 59 flowing through the heat exchanger 58 by reducing the opening degree of the flow control valve 57, and the amount of heat exchanged. Decrease the temperature of the gaseous fuel 51. On the other hand, when the temperature measurement value 54 is lower than the temperature set value 56, the temperature control device 55 opens the flow control valve 57 and exchanges it by increasing the flow rate of the heating fluid 59 flowing through the heat exchanger 58. The amount of heat generated is increased, and the temperature of the gaseous fuel 51 is increased.
[0007]
As described above, the measurement value by the thermometer is fed back, and the heating flow rate of the heat exchanger is PID controlled by the temperature control device 55 to control the gaseous fuel.
[0008]
[Problems to be solved by the invention]
However, when constructing a plant, there are restrictions on the space that can be used, so the installation location of the heat exchanger for gas heating and the installation location of the pressure reducing valve may be greatly separated. In this case, it has been difficult to accurately control the temperature by the conventional method. The reason why this control becomes unstable is that the delay time until the gas heated by the heat exchanger reaches the position of the thermometer downstream of the pressure reducing valve increases and changes.
[0009]
That is, when the flow rate of gaseous fuel is large, the flow rate is fast, so that the delay time is relatively small and stable in terms of control. Since it becomes large, the problem that control becomes unstable arises. This instability of control is because the delay time included in the control system is large, and furthermore, this delay time is not constant but varies depending on the driving situation. Therefore, controlling such objects with a controller based on a single PID constant as described in the prior art is inherently limited.
[0010]
As a method for controlling the process in which the control characteristic of the target changes, a method using modeling is known. This method models an object, predicts a state quantity to be controlled based on the model, and determines an operation amount based on the predicted value.
[0011]
However, this method is based on the premise that the target is properly modeled, but it is generally difficult to obtain accurate information about the target. There are many difficulties. In addition, even when accurate information is available, a means for obtaining an accurate state quantity from an object that changes from time to time is provided, and an appropriate control parameter is determined in accordance with the state quantity to determine the controller. If processing for changing parameters is performed, it is inevitable that the control device becomes complicated.
[0012]
The present invention has been made in view of such problems of the prior art, and is relatively simple control even when the distance between the heat exchanger and the pressure reducing valve is large and the gas flow rate is slow. An object of the present invention is to provide a gas temperature control device capable of stable temperature control by a system.
[0015]
[Means for Solving the Problems]
To solve the above problems The gas temperature control device according to the present invention is a gas temperature control device in a pipeline comprising a heat exchange facility for heating or cooling a gas, and an enthalpy change process disposed downstream of the heat exchange facility. A target enthalpy possessed by the gas after passing through the process is calculated from means for setting and inputting the target pressure value and first target temperature value of the gas after passing through the process, and the target pressure value and the first target temperature value. Enthalpy calculating means, the target enthalpy, and temperature calculating means for calculating a second target temperature value of the gas before passing through the process from the actual gas pressure value at the position after passing through the heat exchange equipment before passing through the process; The second target temperature value is corrected from the actual gas temperature value after passing through the process and the first target temperature value before passing through the process. And temperature calculation means for calculating a third target temperature value, as the gas temperature is the third target temperature before the process passes is a configuration and means for controlling the heat exchange equipment.
[0016]
With the configuration as described above, even if the environment is such that the temperature of the gas to be controlled does not necessarily match the target temperature, the target temperature can be controlled.
[0019]
Furthermore, the gas temperature control device of the present invention is a gas temperature control device in a pipeline comprising a heat exchange facility for heating or cooling a gas, and an equal enthalpy change process disposed downstream of the heat exchange facility. Means for setting and inputting a target pressure value and a target temperature value of the gas after passing through the process; and a first enthalpy calculating means for calculating a target enthalpy possessed by the gas after passing through the process from the target pressure value and the target temperature value; A second enthalpy calculating means for calculating an initial enthalpy possessed by the gas from a gas pressure actual value and a gas temperature actual value before passing through the heat exchange equipment, and passing through the target enthalpy, the initial enthalpy and the process. Means for calculating the amount of heat to be exchanged in the heat exchange facility from the mass flow rate of gas, and the amount of heat to be exchanged From the means for calculating the first control target value of the heat exchange equipment to be given to the gas, the actual gas temperature value after passing through the process and the target temperature value, the first control target value of the heat exchange equipment And a means for calculating a second control target value of the heat exchange facility and a means for controlling the heat exchange facility based on the second control target value.
[0020]
By configuring in this way, the gas temperature can be controlled to the target value even in an environment where the temperature of the gas to be controlled does not necessarily match the target temperature.
[0021]
Furthermore, the gas temperature control apparatus according to the present invention is configured to be applicable in a process for reducing the gas pressure.
[0022]
With this configuration, it can be widely applied in many pipelines.
[0023]
Moreover, the gas temperature control apparatus according to the present invention is configured such that the means for controlling the heat exchange facility controls the flow rate of the heat exchange medium used in the heat exchange facility.
[0024]
By comprising in this way, it can control reliably using a general heat exchange installation.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Prior to the description of the embodiments of the present invention, the principle of the present invention will be described.
[0026]
In general, the enthalpy of a substance is represented by the formula (1).
[0027]
H = U + PV (1)
Here, H is enthalpy, U is internal energy, P is pressure, and V is volume.
[0028]
If the equation (1) is applied to a gas, the internal energy U of the gas can be expressed by a function having the temperature T as a parameter. Therefore, the enthalpy H of the gas is 3 of the gas pressure P, volume V, and temperature T. Will be described by two variables.
[0029]
On the other hand, it has been confirmed for real gases that three variables of pressure P, volume V, and temperature T are connected to each other by various approximate relational expressions in various empirical equation of state. Therefore, when this equation of state is used, one of the three variables can be expressed by the remaining two variables. Eventually, the enthalpy H of the gas is the pressure P, volume V, and temperature T. It can be approximately represented by two of the variables.
[0030]
This is apparent from the diagram described in “Chemical Thermodynamic Diagram” by Toru Hara, Chemical Industry Co., Ltd., published in 1970. This document contains a diagram representing the enthalpy of a certain gas by pressure and temperature.
[0031]
FIG. 1 is a diagram schematically showing the relationship among enthalpy H, pressure P, and temperature T based on the diagram described in the prior art document.
[0032]
In this figure, the vertical axis represents pressure P, the horizontal axis represents enthalpy H, and temperature T is expressed as a parameter. It can be seen from this figure that the enthalpy is H1 when the pressure is P1 and the temperature is T1, and that the enthalpy is H2 when the pressure is P1 and the temperature is T2.
[0033]
Therefore, the relationship can be expressed by equation (2) using the function F.
[0034]
H = F (P, T) (2)
Furthermore, contrary to the above relationship, if the enthalpy H and the pressure P are determined, the temperature T can be uniquely determined.
[0035]
This relationship can be expressed by equation (3) using the function G.
[0036]
T = G (H, P) (3)
Consider the case where gas flows through a porous material or valve. If the change in kinetic energy of the flow is negligibly small, the change in enthalpy of the flow is zero. That is, when passing through a process without heat exchange with the surroundings, the gas enthalpy (thermodynamic energy) before and after passing through the process is preserved. Such a process is called an isoenthalpy change process.
[0037]
The present invention performs temperature control downstream of the pressure reducing valve, which is an isenthalpy change process, using the above-described relationship, and the control method is based on the following two concepts.
[0038]
The control method based on the first idea is to change the position to be controlled for temperature control.
[0039]
The target enthalpy H2 is calculated from the target pressure P2s of the gas after passing through the pressure reducing valve and the target temperature T2s by the equation (4).
[0040]
H2 = F (P2s, T2s) (4)
On the other hand, since the pressure reducing valve is an isoenthalpy changing process, the gas enthalpy is preserved before and after passing through the pressure reducing valve. Therefore, the gas temperature target value T1s before passing through the pressure reducing valve can be obtained by the equation (5) using the gas pressure measured value P1 before passing through the pressure reducing valve and the target enthalpy H2.
[0041]
T1s = G (H2, P1) (5)
By substituting equation (4) into equation (5), equation (6) is obtained.
[0042]
T1s = G (F (P2s, T2s), P1) (6)
As a result, it is shown that the temperature after passing through the pressure reducing valve can be controlled to the target temperature, for example, by controlling the temperature immediately after the heat exchanger with the gas temperature target value obtained by the equation (6).
[0043]
For this reason, it becomes possible to change the control target position to be temperature controlled from the position after the pressure reducing valve to the position immediately after the heat exchanger, and the delay time associated with the movement of gas, which is a problem in temperature control. Can be minimized.
[0044]
The control method based on the second idea is to change the control object from temperature to heat exchange amount.
[0045]
When the mass flow rate K (Kg / H), which is the weight per unit time of the gas, can be measured, first calculate from the initial pressure P0 and initial temperature T0 of the gas before the heat exchanger inlet using the equation (7) Using the initial enthalpy H0 and the target enthalpy H2 obtained using the equation (4), the heat quantity Q per unit time to be given by the heat exchanger can be calculated by the equation (8).
[0046]
H0 = F (P0, T0) (7)
Q = (H2-H0) x K (8)
This equation (8) indicates that the amount of heat to be given by the heat exchanger has already been obtained by measuring the gas pressure P0 and the gas temperature T0 before being input to the heat exchanger.
[0047]
In general, since the temperature of a substance changes due to heat transfer, the temperature control for a substance having a low heat transfer coefficient such as gas has a large time constant and is not responsive. Therefore, sufficient time is required until the gas temperature is controlled to a constant value.
[0048]
However, even in such a case, since the necessary heat exchange amount can be quantified by the equation (8), if the heat exchanger is adjusted in advance so that the predetermined heat exchange is performed, the responsiveness of the temperature control is further improved. It can be further enhanced.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a block diagram showing a first embodiment of the temperature control apparatus according to the present invention. First, a process to be controlled will be described.
[0049]
In the fuel line 1 through which the gaseous fuel flows, a heat exchanger 12 for heating the gaseous fuel and a pressure reducing valve 6 for adjusting the pressure of the gaseous fuel are installed, and temperature control is performed using these facilities. The pre-heating thermometer 2, the pre-heating pressure gauge 3, the upstream thermometer 4, the upstream pressure gauge 5, the downstream thermometer 7, the downstream pressure gauge 8, and the downstream flow meter 9 are provided.
[0050]
The heating line 10 for heating the gaseous fuel flowing through the fuel line 1 is necessary to control the heating flow rate control valve 14 for adjusting the flow rate of the heating fluid supplied to the heat exchanger 12 and the heating flow rate control. A heat exchanger inlet thermometer 11, a heat exchanger outlet thermometer 13, and a heating flow meter 15 are provided.
[0051]
In order to control the fuel gas temperature of the plant configured as described above, the gas temperature control device 20 according to the present invention sets the downstream pressure setter 21 for setting the pressure target value to be controlled and the first target temperature value. A downstream temperature setter 22 for setting, a downstream pressure adjusting unit 23 for adjusting the pressure of the fuel gas, an enthalpy calculation processing unit 24 for calculating an upstream temperature target value which is a second target temperature value by performing calculations related to enthalpy, and the upstream An upstream temperature adjustment unit 25 that outputs a heating flow rate target value based on the temperature target value and a heating flow rate adjustment unit 26 that controls the heating flow rate according to the heating flow rate target value are configured.
[0052]
The enthalpy calculation processing unit 24 calculates an enthalpy calculation processing unit 24a that calculates a target enthalpy H2 from the downstream pressure target value and the downstream temperature target value, and calculates an upstream temperature target value from the target enthalpy H2 and the upstream pressure measurement value P1. It is comprised by the temperature calculation process part 24b.
[0053]
Next, the operation of the above apparatus will be described.
[0054]
First, the target values of the pressure and temperature of the gaseous fuel to be controlled are set using the downstream pressure setting device 21 and the downstream temperature setting device 22. Based on the set downstream pressure target value P2, the downstream pressure adjusting unit 23 controls the pressure, which is one of the downstream control targets, to a predetermined value.
[0055]
In parallel with this, in the enthalpy calculation processing unit 24, the enthalpy calculation processing unit 24a calculates the target enthalpy H2 from the set downstream pressure target value P2s and the downstream temperature target value T2s, and the temperature calculation processing unit 24b. However, the upstream temperature target value T1s is calculated from the target enthalpy H2 and the upstream pressure P1.
[0056]
The calculation of the target enthalpy H2 and the upstream temperature target value T1s in the enthalpy calculation processing unit 24 is performed based on the following principle and method.
[0057]
The inventors made extensive studies on a calculation method for obtaining enthalpy H by pressure P and temperature T. As a result, the gas fuel, which is a mixed gas composed of a plurality of gas compositions, is different from the diagram shown in FIG. 1 relating to a single-composition gas, but is a diagram in which equations (2) and (3) are established. It was also found that enthalpy H can be expressed approximately by the following equation (9) within the temperature and pressure range in which the gaseous fuel is used.
[0058]
H = A (P) × B (T) + C (P) (9)
Here, A and C represent a function of the pressure P, and B represents a function of the temperature T.
[0059]
On the other hand, if the equation (9) is used, the temperature T is expressed by the equation (10) by the enthalpy H and the pressure P.
[0060]
B (T) = {HC (P)} / A (P) (10)
If B (T) is obtained, T can be obtained by its inverse function.
[0061]
FIG. 3 shows a method for expressing a function in this apparatus. In this device, function functions are realized for functions A, B, and C for obtaining enthalpy H by using a function called a function block that expresses an arbitrary function by broken line approximation connecting up to six registered points. is doing.
[0062]
In addition, instead of the function block, a two-dimensional table shown in FIG. 4 can be created and values can be obtained by referring to the table. This table obtains the enthalpy H from the pressure P and the temperature T, and stores the value obtained by dividing the range of the pressure P in the column direction and stores the value obtained by dividing the range of the temperature T in the row direction. is there.
[0063]
Using this table, for example, the value of enthalpy at pressure P2 and temperature T2 can be obtained as H22 at the intersection of the corresponding matrix in FIG. If the pressure Pn and the temperature Tn are in the middle of the values obtained by dividing the range, that is, in the relation of the expression (11), the enthalpy Hn can be obtained by the expression (12).
[0064]
P1 <Pn <P2, T1 <Tn <T2 (11)
Hn = Ha + (Tn−T1) × (Hb−Ha) / (T2−T1) (12)
Here, Ha = H11 + (Pn−P1) × (H21−H11) / (P2−P1)
Hb = H12 + (Pn−P1) × (H22−H12) / (P2−P1)
FIG. 5 shows a configuration of the enthalpy calculation processing unit 24a according to the present invention.
[0065]
This process consists of a function block that outputs a value of a predetermined function corresponding to the input value, a multiplication block that multiplies the input values and outputs the result, and an addition block that adds a plurality of input values and outputs the result It is composed by.
[0066]
In FIG. 5, the downstream pressure target value P2 is input to the function block 30 and the function block 32, and a value A (P2s) corresponding to a predetermined function A and a value C (P2s) corresponding to the function C are calculated. Further, the downstream temperature target value T2s is input to the function block 31, and a value B (T2s) corresponding to a predetermined function B is calculated.
[0067]
Subsequently, the result obtained by multiplying the value A (P2s) and the value B (T2s) by the multiplication block 33 is added to the value C (P2s) by the addition block 34 to calculate the target enthalpy H2.
[0068]
With the above operation, the enthalpy processing unit 24a calculates the enthalpy based on the equation (9).
[0069]
FIG. 6 shows the configuration of the temperature calculation processing unit 24b.
[0070]
This processing unit is a function block that outputs a value of a predetermined function corresponding to an input value, a subtraction block that subtracts the input values and outputs a result, and a division that divides the input values and outputs the result It consists of blocks.
[0071]
In FIG. 6, the upstream pressure P1 is input to the function block 30 and the function block 32, and a value A (P1) corresponding to a predetermined function A and a value C (P1) corresponding to the function C are calculated. Subsequently, a value obtained by subtracting the value C (P1) from the target enthalpy H2 is calculated by the subtraction block 35, and this result and the value A (P1) are divided by the division block 36 to obtain the function value B of the upstream temperature target value T1s. (T1s) is obtained. Further, this value B (T1s) is input to a function block 37 configured to output an inverse function of the function B, and an upstream temperature target value T1s based on the equation (10) is calculated.
[0072]
The upstream temperature target value T1s obtained by the operation of the temperature calculation processing unit 24b described above is input as a set value of the upstream temperature adjustment unit 25 shown in FIG. The upstream temperature adjustment unit 25 obtains a deviation between the upstream temperature target value T1s and the measured upstream temperature T1, and inputs a control signal FLs corresponding to the deviation to the heating flow rate adjustment unit 26. The heating flow rate adjusting unit 26 constitutes a control loop for the heating fluid flow rate FL, and performs cascade control for changing the heating flow rate target value in response to the control signal FLs, so that the upstream temperature T1 has a high response to the upstream temperature target value. Control to T1s.
[0073]
The reason why cascade control is used in the configuration of this control system is to increase the responsiveness of temperature control. However, when the responsiveness is not particularly required, as shown in FIG. The adjusting unit 26 may be omitted, and the heating flow rate adjusting valve 14 may be directly controlled by the output of the upstream temperature adjusting unit 25.
[0074]
By configuring as described above, the control target position to be temperature-controlled can be changed from the position after the pressure reducing valve to the position immediately after the heat exchanger, which is accompanied by the movement of gas, which is a problem in temperature control. The generation of the delay time can be minimized, and the control can be performed with high accuracy by a simple configuration.
[0075]
In the present embodiment, the temperature of the gaseous fuel is controlled by controlling the heating fluid flowing through the heat exchanger. However, the gaseous fuel is cooled by cooling means such as flowing a cooling fluid instead of the heating fluid. In this case, the temperature can be controlled by an apparatus configured in the same manner as in this embodiment.
[0076]
Next, FIG. 8 shows a control block diagram as a second embodiment of the temperature control apparatus according to the present invention.
[0077]
To describe the present embodiment, only the main part will be described here, and the same components as those of the first embodiment described in FIG. 2 will not be described again. Quote with the number.
[0078]
In the present embodiment, in addition to the control device of the first embodiment, a downstream temperature adjustment unit 27 and an adder 28 are newly provided.
[0079]
A downstream temperature target value T2s and a downstream temperature T2, which are first target temperature values, are input to the downstream temperature adjusting unit 27, and a control signal corresponding to the deviation between the two signals is output to the adder 28. In the adder 28, a value obtained by adding the control signal to the upstream temperature target value that is the second target temperature value calculated by the enthalpy calculation processing unit 24 is used as a new upstream temperature target value T1s that is the third target temperature value. To the upstream temperature control unit 25.
[0080]
If the downstream temperature T2 is lower than the set value T2s, the downstream temperature adjustment unit 27 outputs a positive control signal. Therefore, the upstream temperature target value T1s given as the set value of the upstream temperature adjustment unit 25 is enthalpy. The value is larger than the calculation result of the calculation processing unit 24. For this reason, the heating flow rate adjusting unit 26 adjusts the opening degree of the heating flow rate adjusting valve 14 so that a larger heating flow rate flows.
[0081]
When the downstream temperature T2 is higher than the set value T2s, the heating flow rate adjusting unit 26 adjusts the opening degree of the heating flow rate adjusting valve 14 so that a smaller heating flow rate flows by the reverse operation of the control operation described above.
[0082]
As described above, in the present embodiment, the set value T1s of the upstream temperature adjustment unit 25 is not determined only by the calculation result of the enthalpy calculation processing unit 24, but is corrected by the downstream temperature T2.
[0083]
By configuring as described above, for example, when the accuracy of enthalpy calculation is not good, even when the downstream temperature T2 does not necessarily match the target temperature due to seasonal fluctuations in the amount of heat released from the piping, or other factors, the downstream The target temperature can be reached by feeding back the value of the temperature T2.
[0084]
In the present embodiment, the temperature of the gaseous fuel is controlled by controlling the heating fluid flowing through the heat exchanger. However, the gaseous fuel is cooled by cooling means such as flowing a cooling fluid instead of the heating fluid. In this case, the temperature can be controlled by an apparatus configured in the same manner as in this embodiment.
[0085]
Next, FIG. 9 shows a control block diagram which is a third embodiment of the gas temperature control apparatus according to the present invention.
[0086]
The gas temperature control device 40 according to the third embodiment relates to a downstream pressure setting device 41 and a downstream temperature setting device 42 for setting a target value to be controlled, a downstream pressure adjusting unit 43 for adjusting the pressure of the fuel gas, and enthalpy. An enthalpy calculation processing unit 44 that performs calculation to calculate a heating flow rate target value and a heating flow rate adjustment unit 48 that controls the heating flow rate according to the heating flow rate target value constitute main control parts.
[0087]
Further, in order to improve the control performance, a downstream temperature adjusting unit 46 and an adder 47 for outputting a heating flow rate correction value based on the target value of the downstream temperature setting unit 42 are provided.
[0088]
The enthalpy calculation processing unit 44 is a target enthalpy calculation processing unit 44a that calculates a target enthalpy H2 that is a first enthalpy from the downstream pressure target value P2s and the downstream temperature target value T2s, a preheating pressure P0, and a preheating temperature T0. The initial enthalpy calculation processing unit 44c for calculating the initial enthalpy H0, which is the second enthalpy, calculates the amount of heat to be exchanged from the target enthalpy H2 and the initial enthalpy H0, etc., and the heating flow rate target which is the first control target value The target flow rate calculation processing unit 44b outputs a value.
[0089]
Next, the operation of the above apparatus will be described.
[0090]
The configuration of the process that is the object of gas temperature control in the third and third embodiments is the same as that of the first embodiment described with reference to FIG. 2 and therefore will not be described again here. In the following description, the same numbers are used for reference.
[0091]
First, the target values of the pressure and temperature of the gaseous fuel to be controlled are set using the downstream pressure setting device 41 and the downstream temperature setting device 42. Based on the set downstream pressure target value P2s, the downstream pressure adjustment unit 43 controls the downstream pressure P2, which is one of the downstream fluid conditions, to a predetermined value. In parallel with this, the target enthalpy calculation processing unit 44a calculates the target enthalpy H2 from the set downstream input pressure value P2 and the downstream temperature target value T2, while the initial enthalpy calculation processing unit 44c calculates the pre-heating pressure P0. And the initial enthalpy H0 is calculated from the temperature T0 before heating. These enthalpy calculation methods are performed using the function blocks described in the first embodiment.
[0092]
Subsequently, the target flow rate calculation processing unit 44b calculates a heating flow rate target value to be passed through the heat exchanger 12, and this calculation method will be described below.
[0093]
If it is considered that the initial enthalpy H0 is given the heat quantity Qs by the heat exchanger 12 and becomes the target enthalpy H2, equation (13) is established.
[0094]
Qs = (H2-H0) * Fg (13)
Here, Fg is the downstream flow rate measured by the downstream flow meter 9.
[0095]
The amount of heat Qr given by the heat exchanger is considered to be the amount of heat lost by the heating fluid before and after the heat exchanger.
Qr = (T0−T1) × FL × CL (14)
Here, T0 is the temperature measured by the heat exchanger inlet thermometer 11.
T1 is the temperature measured by the heat exchanger outlet thermometer 13
FL is a flow rate measured by the heating flow meter 15.
CL is the specific heat of the heating fluid
Therefore, the flow target value FLs of the heated fluid so that Qs and Qr are equal is expressed by equation (15).
[0096]
FLs = (H2−H0) × Fg / (T0−T1) / FL (15)
The operation will be described with reference to the configuration of the target flow rate calculation process 44b shown in FIG.
[0097]
First, the subtraction between the target enthalpy H2 and the initial enthalpy H0 is calculated by the subtraction block 38a, and then the multiplication block 38b is multiplied by the downstream flow rate Fg to calculate the heat quantity Qs. The subtraction result of the heat exchanger inlet temperature T0 and the heat exchanger outlet temperature T1, which is the output of the subtractor 45, is input to the multiplication block 38c and multiplied by the heating fluid specific heat CL. This result is input to the division block 38d, and is divided by Qs that is the calculation result to calculate the heating flow rate target value FLs that is the first control target value.
[0098]
On the other hand, the downstream temperature target value T2s and the downstream temperature T2 are input to the downstream temperature adjustment unit 46, and the downstream temperature adjustment unit 46 outputs a control signal corresponding to the deviation between both signals to the adder 47. In the adder 47, a value obtained by adding the control signal to the heating flow rate target value FLs that is the first control target value is used as a new heating flow rate target value FLa that is the second control target value. Output to. The heating flow rate adjusting unit 48 outputs a control signal to the heating flow rate adjusting valve 14 corresponding to the deviation between the heating flow rate target value FLa and the heating flow rate FL, and controls the heating flow rate to a predetermined value.
[0099]
By configuring as described above, the flow rate of the heating fluid to be flowed to the heat exchanger can be determined in advance based on the pressure and temperature before heating the gaseous fuel, so that the gaseous fuel can be quickly controlled to a predetermined temperature.
[0100]
In addition to the above configuration, since the control system is configured to perform correction based on the downstream temperature T2, the downstream temperature can be further accurately controlled to the target temperature.
[0101]
Further, in the third embodiment, the correction is made based on the downstream temperature T2, but the correction is made based on the upstream temperature T1 by configuring the same as in the first embodiment. May be performed.
[0102]
In this embodiment, the temperature of the gaseous fuel is controlled by controlling the heated fluid flowing through the heat exchanger. However, the gaseous fuel is cooled by cooling means such as flowing a cooling fluid instead of the heated fluid. In this case, the temperature can be controlled by an apparatus configured in the same manner as in this embodiment.
Furthermore, the technology related to the method for controlling the temperature in the isoenthalpy change process described in the present invention does not use a heat exchanger, for example, has a means for controlling the temperature by mixing the heated fluid and the fluid to be heated. It can also be applied to processes.
[0103]
【The invention's effect】
As described above, according to the present invention, by utilizing the fact that the gas enthalpy before and after passing through the isoenthalpy change process is stored, the position to be controlled should be controlled from the position after the pressure reducing valve to the position immediately after the heat exchanger. Since it is possible to change the position, the delay time associated with the movement of the gas, which is a problem in temperature control even when the heat exchanger and the pressure reducing valve are arranged apart from each other, is considered. The influence can be minimized and stable temperature control becomes possible.
[0104]
In addition, since the present invention can quantify the amount of heat exchange required before passing through the isoenthalpy change process, it can be controlled to carry out heat exchange in advance, so compared to the case where temperature control is performed by feedback control. In addition, the responsiveness of temperature control can be further improved.
[0105]
Furthermore, the enthalpy calculation used in the present invention does not require special processing such as performing complicated modeling on the controlled object and identifying characteristic changes of the model, so that the apparatus can be realized with a relatively simple configuration. it can.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing the relationship between enthalpy H, pressure P, and temperature T. FIG.
FIG. 2 is a configuration diagram showing a first embodiment of a gas temperature control device of the present invention.
FIG. 3 is a diagram showing a function in a polygonal line approximation in the gas temperature control device of the present invention.
FIG. 4 is a diagram showing functions in a temperature and pressure table in the gas temperature control apparatus of the present invention.
FIG. 5 is a diagram showing a configuration of an enthalpy calculation processing unit in the gas temperature control device of the present invention.
FIG. 6 is a diagram showing a configuration of a temperature calculation processing unit in the gas temperature control device of the present invention.
FIG. 7 is a configuration diagram showing a modification of the first embodiment of the gas temperature control device of the present invention.
FIG. 8 is a configuration diagram showing a second embodiment of the gas temperature control device of the present invention.
FIG. 9 is a configuration diagram showing a third embodiment of the gas temperature control device of the present invention.
FIG. 10 is a diagram showing a configuration of a target flow rate calculation processing unit in the gas temperature control device of the present invention.
FIG. 11 is a configuration diagram of a conventional gas temperature control device.
[Explanation of symbols]
1 ... Fuel line
2 ... Thermometer before heating
3. Pressure gauge before heating
4 ... Upstream thermometer
5 ... Upstream pressure gauge
6 ... Pressure reducing valve
7. Downstream thermometer
8 ... Downstream pressure gauge
9 ... Downstream flow meter
10 ... Heating line
12 ... Heat exchanger
15 ... Heating flow meter
20 ... Gas temperature control device
21 ... Downstream pressure setting device
22 ... Downstream temperature setter
23 ... Downstream pressure adjustment unit
24. Enthalpy calculation processing unit
24a ... enthalpy calculation processing unit
24b ... Temperature calculation processing unit
25 ... Upstream temperature control section
26 ... Heating flow rate control unit
27 ... Downstream temperature control unit
28 ... Adder
40. Gas temperature control device
41 ... Downstream pressure setting device
42 ... Downstream temperature setting device
43. Downstream pressure adjustment unit
44. Enthalpy calculation processing unit
44a ... Target enthalpy calculation processing unit
44b ... Target flow rate calculation processing unit
44c ... Initial enthalpy calculation processing section
46. Downstream temperature control unit
48 ... Heating flow rate control unit
51 ... Gaseous fuel
52. Pressure reducing valve
53 ... Thermometer
55 ... Temperature control device
57 ... Flow control valve
58 ... Heat exchanger

Claims (4)

In a gas temperature control device in a pipeline comprising a heat exchange facility for heating or cooling gas, and an isenthalpy change process arranged downstream of the heat exchange facility,
Means for setting and inputting a target pressure value of the gas after passing through the process and a first target temperature value;
Enthalpy calculating means for calculating a target enthalpy possessed by the gas after passing through the process from the target pressure value and the first target temperature value;
A temperature calculation means for calculating a second target temperature value of the gas before passing through the process from the target enthalpy and the gas pressure actual value at a position after passing through the heat exchange facility before passing through the process;
A temperature calculating means for correcting the second target temperature value from the gas temperature actual value after the process and the first target temperature value to calculate a third target temperature value before the process;
A gas temperature control apparatus comprising: means for controlling the heat exchange facility so that the gas temperature before passing through the process becomes the third target temperature value. In a gas temperature control device in a pipeline comprising a heat exchange facility for heating or cooling gas, and an isenthalpy change process arranged downstream of the heat exchange facility,
Means for setting and inputting a target pressure value and a target temperature value of the gas after passing through the process;
First enthalpy calculating means for calculating a target enthalpy possessed by the gas after passing through the process from the target pressure value and the target temperature value;
A second enthalpy calculating means for calculating an initial enthalpy possessed by the gas from a gas pressure actual value and a gas temperature actual value before passing through the heat exchange facility;
First control of the heat exchange equipment is calculated such that the heat quantity to be exchanged in the heat exchange equipment is calculated from the target enthalpy, the initial enthalpy and the mass flow rate of the gas passing through the process, and the heat quantity is given to the gas Means for calculating a target value;
Means for correcting the first control target value of the heat exchange facility and calculating the second control target value of the heat exchange facility from the actual gas temperature value after the process and the target temperature value;
A gas temperature control device comprising: means for controlling the heat exchange facility based on the second control target value. In the gas temperature control device according to claim 1 or 2 ,
The isoenthalpy changing process is a process of reducing the gas pressure, and a gas temperature control device. In the gas temperature control device according to claim 1 or 2 ,
The gas temperature control apparatus according to claim 1, wherein the means for controlling the heat exchange equipment controls a flow rate of a heat exchange medium used in the equipment.

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