CN116221701A - Steady state operation system and method of electric boiler under extremely low power - Google Patents

Abstract

The invention discloses a steady-state operation system and a steady-state operation method of an electric boiler under extremely low power, wherein the steady-state operation system comprises the following steps: under extremely low power, the electric boiler is controlled by adopting a combined control mode of an electric boiler pressure signal and an electric boiler inner cylinder water level signal, under the condition that the electric conductivity of water in the electric boiler inner cylinder is kept stable, a first buffer control pressure and a second buffer control pressure are arranged in the range from the electric boiler power-on starting pressure to the opening and stopping pressure, wherein the first buffer control pressure is used as an initial water discharge pressure signal of the electric boiler inner cylinder, the second buffer control pressure is used as an initial water supplementing pressure signal of the electric boiler inner cylinder, and simultaneously, three-phase electrodes are kept in a continuous power-on state, and the electric boiler power is stabilized and the pressure is regulated according to the water level of the electric boiler inner cylinder.

Description

Steady state operation system and method of electric boiler under extremely low power

Technical Field

The invention belongs to the technical field of control of electric boilers in nuclear power plants, and relates to a steady-state operation system and method of an electric boiler under extremely low power.

Background

The power control system of the electric boiler of the nuclear power plant is complex, and relates to various influencing factors such as temperature control, pressure control, chemical control, electric control and the like. In the prior art of an electric boiler used in a nuclear power plant, when the electric boiler runs under extremely low load (less than 10% of rated full load), a pressure control mode is generally adopted, namely, a certain pressure set value is given to the electric boiler, when the pressure reaches the set value, the power supply of the electric boiler is disconnected, and the electric boiler stops heating; when the pressure is lower than a certain value, the power supply of the electric boiler is switched on, and the electric boiler continues to heat and boost. Because the thermal inertia of the electric boiler is large, the load fluctuation control interval of the electric boiler is small under the extremely low load state, the pressure regulation mode leads the boiler electric rate to rise and fall in a pulse mode, the power supply instruction is frequent, the electric switch is switched on and off in a circulating mode, and the electric appliance switching loss is increased. Meanwhile, the hysteresis of the pressure relative to the electric power is obvious, the pressure is also increased and decreased in a steep slope manner, pressure overshoot is easy to cause, larger control deviation is caused, stress fatigue is also formed due to larger fluctuation of the pressure in a short period, and the service life of the thermodynamic equipment is reduced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a steady-state operation system and a steady-state operation method of an electric boiler under extremely low power, which can avoid the problems of frequent starting and stopping of the electric boiler during extremely low-load steady-state operation and are not easy to cause pressure overshoot.

In order to achieve the above object, the steady-state operation method of the electric boiler under extremely low power according to the present invention comprises the steps of:

under extremely low power, the electric boiler is controlled by adopting a combined control mode of an electric boiler pressure signal and an electric boiler inner barrel water level signal, under the condition that the electric conductivity of water in the electric boiler inner barrel is kept stable, a first buffer control pressure and a second buffer control pressure are arranged in the range from the electric boiler power-on starting pressure to the opening and stopping pressure, wherein the first buffer control pressure is used as an electric boiler inner barrel initial water discharge pressure signal, the second buffer control pressure is used as an electric boiler inner barrel initial water supplementing pressure signal, and meanwhile, three-phase electrodes are kept in a continuous power-on state, and the electric boiler power is stabilized and the pressure is adjusted according to the water level of the electric boiler inner barrel.

The steady-state operation system of the electric boiler under extremely low power comprises an electric boiler inner cylinder, an electric boiler outer cylinder, a water supply pump, a circulating regulating valve, a vapor pressure sensor, a vapor regulating valve and a vapor output pipeline;

the electric boiler inner cylinder is positioned in the electric boiler outer cylinder, the outlet of the water supply pump is communicated with the water inlet on the side surface of the top of the electric boiler outer cylinder, the outlet at the bottom of the electric boiler outer cylinder is divided into two paths after passing through the circulating pump, one path is communicated with the water inlet on the side surface of the bottom of the electric boiler outer cylinder, the other path is communicated with the water inlet on the side surface of the electric boiler inner cylinder through the circulating regulating valve, and the steam outlet at the top of the electric boiler inner cylinder is communicated with the steam output pipeline through the steam pressure sensor and the steam regulating valve;

the inner cylinder of the electric boiler is internally provided with a pH meter, an inner cylinder water level sensor and three-phase electrodes.

The outlet of the water supply pump is communicated with a water inlet on the side surface of the top of the outer cylinder of the electric boiler through a water supply regulating valve.

The circulating pump is communicated with a water inlet on the side surface of the bottom of the outer cylinder of the electric boiler through a recirculation pore plate.

An inner cylinder drain valve is arranged at the water outlet at the bottom of the inner cylinder of the electric boiler.

A chemical dosing system is arranged on a pipeline between the circulation regulating valve and the water inlet on the side surface of the inner cylinder of the electric boiler.

The chemical dosing system is interlocked with a pH meter.

The steady-state operation method of the electric boiler under the extremely low power comprises the following steps:

1) When the electric boiler operates under extremely low power, the conductivity of water in the inner cylinder of the electric boiler is kept stable through the pH meter and the chemical dosing system; supplying water to the inner cylinder of the electric boiler through a circulating pump, a recirculation pore plate and a circulating regulating valve; draining the inner cylinder of the electric boiler through an inner cylinder drain valve; measuring the water level of an inner cylinder of the electric boiler through an inner cylinder water level sensor; the water supply pump and the water supply regulating valve are used for supplying water to the outer cylinder of the electric boiler; the three-phase electrode is in an electrified state, a steam pressure signal of an inner cylinder of the electric boiler is measured through a steam pressure sensor, and a steam regulating valve keeps a set opening degree to supply steam for a downstream user;

2) Setting the average value of the starting pressure and the stopping pressure of the electric boiler as P, wherein the difference value of the starting pressure and the stopping pressure of the electric boiler is 2 x delta P, the power-on starting pressure of the electric boiler is (P-delta P), and the opening and stopping pressure of the electric boiler is (P+delta P);

3) Setting buffer control pressures P+alpha, delta P and P-alpha, delta P in the range from the electrifying starting pressure (P-delta P) of the electric boiler to the pressure (P+delta P) of the switching off and stopping operation, wherein P+alpha, delta P is used as a pressure signal of initial water discharge of an inner cylinder of the electric boiler, and P-alpha, delta P is used as a pressure signal of initial water supplement of the inner cylinder of the electric boiler;

4) When the conductivity of the water in the inner cylinder of the electric boiler is stable, the power of the electric boiler is in direct proportion to the water level of the inner cylinder of the electric boiler;

5) When the steam pressure of the inner cylinder of the electric boiler rises to P+alpha delta P, opening the drain valve of the inner cylinder until the steam pressure of the inner cylinder of the electric boiler is reduced to P, and then closing the drain valve of the inner cylinder;

6) When the steam pressure of the inner cylinder of the electric boiler is reduced to P-alpha delta P, the circulating pump, the recirculation pore plate and the circulation regulating valve are used for jointly regulating and increasing the water flow to supplement water for the inner cylinder of the electric boiler, and when the steam pressure of the inner cylinder of the electric boiler is increased to P, the circulating pump, the recirculation pore plate and the circulation regulating valve are used for jointly regulating and enabling the water flow to recover to the original flow;

7) When the steam pressure of the inner cylinder of the electric boiler rises to P+delta P, the three-phase electrode is powered off, the electric boiler stops running, the inner cylinder drain valve is closed, the circulation regulating valve is closed, water in the outer cylinder of the electric boiler is recirculated through the circulation pump and the recirculation pore plate until the steam pressure of the inner cylinder of the electric boiler is reduced to P-delta P, at the moment, the three-phase electrode is powered on, the electric boiler is restarted, and the water flow is regulated to the original water flow through the combination of the circulation pump, the recirculation pore plate and the circulation regulating valve.

The invention has the following beneficial effects:

when the steady-state operation system and the method of the electric boiler under the extremely low power are specifically operated, the first buffer control pressure and the second buffer control pressure are arranged in the range from the electrifying starting pressure of the electric boiler to the switching off and stopping pressure, wherein the first buffer control pressure is used as a pressure signal of initial water discharge of the inner cylinder of the electric boiler, the second buffer control pressure is used as a pressure signal of initial water supplement of the inner cylinder of the electric boiler, namely, the buffer control pressure is used as an input of a control signal, so that the electric boiler can not be frequently started and stopped during the extremely low-load steady-state operation, the service life of electric equipment such as an electric switch is prolonged, the power change of the electric boiler is more stable, the corresponding pressure change is also more moderate, the control deviation is small, the overshoot of the pressure is not easy to be caused, the stress fatigue is obviously reduced, and the service life of the thermal equipment is prolonged.

Drawings

FIG. 1 is a schematic diagram of the structure of the present invention;

FIG. 2 is a schematic diagram of power variation and power on-off during operation of an electric boiler prior to optimization in very low power conditions;

FIG. 3 is a schematic diagram of the power and pressure variation of an optimized electric boiler during steady state operation under very low power conditions.

Wherein 1 is a water feeding pump, 2 is a water feeding regulating valve, 3 is an inner cylinder water level sensor, 4 is a three-phase electrode, 5 is a vapor pressure sensor, 6 is a vapor regulating valve, 7 is a pH meter, 8 is a chemical dosing system, 9 is an electric boiler inner cylinder, 10 is an electric boiler outer cylinder, 11 is an inner cylinder drain valve, 12 is a circulating pump, 13 is a recirculation pore plate, and 14 is a circulating regulating valve _。

Detailed Description

In order to make the present invention better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments, but not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

In the accompanying drawings, there is shown a schematic structural diagram in accordance with a disclosed embodiment of the invention. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and their relative sizes, positional relationships shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.

Example 1

The steady-state operation method of the electric boiler under the extremely low power comprises the following steps:

under extremely low power, the electric boiler is controlled by adopting a combined control mode of an electric boiler pressure signal and an electric boiler inner cylinder 9 water level signal, under the condition that the electric conductivity in the electric boiler inner cylinder 9 is kept stable, a first buffer control pressure P+alpha delta P and a second buffer control pressure P-alpha delta P are arranged in the range from the electric boiler electrifying starting pressure (P-delta P) to the opening shutdown pressure (P+delta P), wherein P+alpha delta P is used as an initial water discharge pressure signal of the electric boiler inner cylinder 9, P-alpha delta P is used as an initial water supplementing pressure signal of the electric boiler inner cylinder 9, and meanwhile, the three-phase electrode 4 is kept in a continuous electrifying state, and the electric boiler power is stabilized and the pressure is adjusted according to the water level of the electric boiler inner cylinder 9.

Example two

Referring to fig. 1, the steady-state operation system of the electric boiler under the extremely low power comprises a water supply pump 1, a water supply regulating valve 2, an inner cylinder water level sensor 3, a three-phase electrode 4, a vapor pressure sensor 5, a vapor regulating valve 6, a pH meter 7, a chemical dosing system 8, an electric boiler inner cylinder 9, an electric boiler outer cylinder 10, an inner cylinder drain valve 11, a circulating pump 12, a circulating pore plate 13 and a circulating regulating valve 14;

the electric boiler inner cylinder 9 is positioned in the electric boiler outer cylinder 10, the outlet of the water feeding pump 1 is communicated with the water inlet on the side surface of the top of the electric boiler outer cylinder 10 through the water feeding regulating valve 2, the outlet of the bottom of the electric boiler outer cylinder 10 is divided into two paths through the circulating pump 12, one path is communicated with the water inlet on the side surface of the bottom of the electric boiler outer cylinder 10 through the recirculating orifice 13, the other path is communicated with the water inlet on the side surface of the electric boiler inner cylinder 9 through the circulating regulating valve 14, the water outlet of the bottom of the electric boiler inner cylinder 9 is provided with the inner cylinder drain valve 11, and the steam outlet of the top of the electric boiler inner cylinder 9 is communicated with the steam output pipeline through the steam pressure sensor 5 and the steam regulating valve 6.

The pH meter 7, the inner cylinder water level sensor 3 and the three-phase electrode 4 are arranged in the inner cylinder 9 of the electric boiler; a chemical dosing system 8 is arranged on a pipeline between the circulation regulating valve 14 and a water inlet on the side surface of the inner cylinder 9 of the electric boiler, and the chemical dosing system 8 is interlocked with the pH meter 7.

Example III

The steady-state operation method of the electric boiler under the extremely low power comprises the following steps:

1) The electric boiler is operated at very low power (below 10% rated full load, typically below 3 MW) and the conductivity of the water in the electric boiler inner drum 9 is kept stable by the pH meter 7 and the chemical dosing system 8. The electric boiler inner cylinder 9 is supplied with water by a circulating pump 12, a recirculating orifice 13 and a circulating regulating valve 14; the electric boiler inner tube 9 is drained by the inner tube drain valve 11. The water level of the inner cylinder 9 of the electric boiler is measured by the inner cylinder water level sensor 3. The water supply pump 1 and the water supply regulating valve 2 supply water to the outer cylinder 10 of the electric boiler. The three-phase electrode 4 is in an electrified state, a steam pressure signal of the inner cylinder 9 of the electric boiler is measured through the steam pressure sensor 5, and the steam regulating valve 6 keeps a set opening degree to supply steam for downstream users;

2) The average value of the starting and stopping pressures of the electric boiler is P, the difference value of the starting and stopping pressures is 2 x delta P, the power-on starting pressure of the electric boiler is (P-delta P), and the opening and stopping pressure of the electric boiler is (P+delta P);

3) Setting buffer control pressures P+alpha, delta P and P-alpha, delta P in the range from the electrifying starting pressure (P-delta P) of the electric boiler to the pressure (P+delta P) of the opening and stopping operation, wherein P+alpha, delta P is used as a pressure signal of initial water discharge of the inner cylinder 9 of the electric boiler, P-alpha, delta P is used as a pressure signal of initial water supplement of the inner cylinder 9 of the electric boiler, and alpha takes a value of 0.5-0.8;

4) When the conductivity of the water in the electric boiler inner cylinder 9 is stable, the power of the electric boiler is in direct proportion to the water level of the electric boiler inner cylinder 9;

5) When the steam pressure of the electric boiler inner cylinder 9 rises to P+alpha delta P, opening the inner cylinder drain valve 11 to reduce the water level of the electric boiler inner cylinder 9, and then reducing the power of the electric boiler until the steam pressure of the electric boiler inner cylinder 9 is reduced to P, and closing the inner cylinder drain valve 11 at the moment;

6) When the steam pressure of the electric boiler inner cylinder 9 is reduced to P-alpha delta P, the circulating pump 12, the recirculation orifice plate 13 and the circulating regulating valve 14 are used for jointly regulating the water flow to supplement water for the electric boiler inner cylinder 9 so as to improve the electric boiler power, and when the steam pressure of the electric boiler inner cylinder 9 is increased to P, the circulating pump 12, the recirculation orifice plate 13 and the circulating regulating valve 14 are used for jointly regulating the water flow to restore the original flow;

7) When the steam pressure of the electric boiler inner cylinder 9 rises to P+delta P, the three-phase electrode 4 is powered off, the electric boiler stops running, the inner cylinder drain valve 11 is closed, the circulation regulating valve 14 is closed, water in the electric boiler outer cylinder 10 is recirculated through the circulation pump 12 and the recirculation orifice 13 until the steam pressure of the electric boiler inner cylinder 9 is reduced to P-delta P, the three-phase electrode 4 is powered on, and the electric boiler is restarted, and at the moment, the water flow is regulated to the original water flow through the combination of the circulation pump 12, the recirculation orifice 13 and the circulation regulating valve 14.

Example IV

The average steam load for the downstream of an electric boiler is about 1.1MW, P is 1.2MPa, the power fluctuation interval before optimization is 0-2.9MW, and the pressure fluctuation range is 0.99-1.25MPa.

Referring to fig. 2 and 3, the present invention is applied: when the delta P is 0.1MPa and the alpha is 0.7, the power on/off frequency of the power supply of the electric boiler is reduced to 10% of the original power on/off frequency, the power fluctuation range is 0.55-1.73MW, and the pressure fluctuation range is 1.01-1.22MPa. The range of power and pressure fluctuation is obviously reduced, the mean square error is obviously reduced, and the stability and economy of the system are obviously improved.

Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims (8)

1. A method of steady state operation of an electric boiler at very low power comprising the steps of:

under extremely low power, the electric boiler is controlled by adopting a combined control mode of an electric boiler pressure signal and an electric boiler inner cylinder (9) water level signal, under the condition of keeping the water conductivity in the electric boiler inner cylinder (9) stable, a first buffer control pressure and a second buffer control pressure are arranged in the range from the electric boiler electrifying starting pressure to the opening and stopping pressure, wherein the first buffer control pressure is used as a pressure signal of initial water discharge of the electric boiler inner cylinder (9), the second buffer control pressure is used as a pressure signal of initial water supplement of the electric boiler inner cylinder (9), and meanwhile, the three-phase electrode (4) is kept in a continuous electrifying state, and the electric boiler power is stabilized and the pressure is adjusted according to the water level of the electric boiler inner cylinder (9).

2. The steady-state operation system of the electric boiler under the extremely low power is characterized by comprising an electric boiler inner cylinder (9), an electric boiler outer cylinder (10), a water supply pump (1), a circulating pump (12), a circulating regulating valve (14), a vapor pressure sensor (5), a vapor regulating valve (6) and a vapor output pipeline;

the electric boiler inner cylinder (9) is positioned in the electric boiler outer cylinder (10), the outlet of the water feeding pump (1) is communicated with the water inlet on the side surface of the top of the electric boiler outer cylinder (10), the outlet at the bottom of the electric boiler outer cylinder (10) is divided into two paths after passing through the circulating pump (12), one path is communicated with the water inlet on the side surface of the bottom of the electric boiler outer cylinder (10), the other path is communicated with the water inlet on the side surface of the electric boiler inner cylinder (9) through the circulating regulating valve (14), and the steam outlet at the top of the electric boiler inner cylinder (9) is communicated with the steam output pipeline through the steam pressure sensor (5) and the steam regulating valve (6);

the electric boiler inner cylinder (9) is internally provided with a pH meter (7), an inner cylinder water level sensor (3) and a three-phase electrode (4).

3. Steady state operation system of an electric boiler at very low power according to claim 2, characterized in that the outlet of the feed water pump (1) is connected via a feed water regulating valve (2) to the water inlet on the top side of the outer vessel (10) of the electric boiler.

4. Steady state operation system of an electric boiler at very low power according to claim 2, characterized in that the circulation pump (12) communicates with the water inlet on the bottom side of the electric boiler outer vessel (10) via a recirculation orifice plate (13).

5. Steady state operation system of an electric boiler at very low power according to claim 2, characterized in that an inner drum drain valve (11) is provided at the drain opening at the bottom of the inner drum (9) of the electric boiler.

6. Steady state operation system of an electric boiler at very low power according to claim 2, characterized in that a chemical dosing system (8) is arranged on the pipe between the circulation regulating valve (14) and the water inlet on the side of the electric boiler inner cylinder (9).

7. The steady state operation system of an electric boiler at very low power according to claim 6, characterized in that the chemical dosing system (8) is interlocked with a pH meter (7).

8. A method of steady state operation of an electric boiler at very low power, characterized by the following steps based on the steady state operation system of an electric boiler at very low power according to any of claims 2-7:

1) When the electric boiler operates under extremely low power, the conductivity of water in the inner cylinder (9) of the electric boiler is kept stable through the pH meter (7) and the chemical dosing system (8); the water is supplied to the inner cylinder (9) of the electric boiler through a circulating pump (12), a recirculating orifice plate (13) and a circulating regulating valve (14); draining the inner cylinder (9) of the electric boiler through an inner cylinder drain valve (11); measuring the water level of an inner cylinder (9) of the electric boiler through an inner cylinder water level sensor (3); the water supply pump (1) and the water supply regulating valve (2) are used for supplying water to the outer cylinder (10) of the electric boiler; the three-phase electrode (4) is in an electrified state, a steam pressure signal of an inner cylinder (9) of the electric boiler is measured through the steam pressure sensor (5), and the steam regulating valve (6) keeps a set opening degree to supply steam for a downstream user;

2) Setting the average value of the starting pressure and the stopping pressure of the electric boiler as P, wherein the difference value of the starting pressure and the stopping pressure of the electric boiler is 2 x delta P, the power-on starting pressure of the electric boiler is (P-delta P), and the opening and stopping pressure of the electric boiler is (P+delta P);

3) Setting buffer control pressures P+alpha, delta P and P-alpha, delta P in the range from the electrifying starting pressure (P-delta P) of the electric boiler to the pressure (P+delta P) of the switching off and stopping operation, wherein P+alpha, delta P is used as a pressure signal of initial water discharge of the inner cylinder (9) of the electric boiler, and P-alpha, delta P is used as a pressure signal of initial water supply of the inner cylinder (9) of the electric boiler;

4) When the conductivity of the water in the electric boiler inner cylinder (9) is stable, the power of the electric boiler is in direct proportion to the water level of the electric boiler inner cylinder (9);

5) When the steam pressure of the inner cylinder (9) of the electric boiler rises to P+alpha delta P, opening the inner cylinder drain valve (11) until the steam pressure of the inner cylinder (9) of the electric boiler is reduced to P, and then closing the inner cylinder drain valve (11);

6) When the steam pressure of the inner cylinder (9) of the electric boiler is reduced to P-alpha delta P, the circulating pump (12), the recirculation orifice plate (13) and the circulation regulating valve (14) are used for jointly regulating the water flow to supplement water for the inner cylinder (9) of the electric boiler, and when the steam pressure of the inner cylinder (9) of the electric boiler is increased to P, the circulating pump (12), the recirculation orifice plate (13) and the circulation regulating valve (14) are used for jointly regulating the water flow to restore the original flow;

7) When the steam pressure of the electric boiler inner cylinder (9) rises to P+delta P, the three-phase electrode (4) is powered off, the electric boiler stops running, the inner cylinder drain valve (11) is closed, the circulation regulating valve (14) is closed, water in the electric boiler outer cylinder (10) is recycled through the circulation pump (12) and the recirculation pore plate (13) until the steam pressure of the electric boiler inner cylinder (9) is reduced to P-delta P, at the moment, the three-phase electrode (4) is powered on, the electric boiler is restarted, and the water flow is regulated to the original water flow through the combination of the circulation pump (12), the recirculation pore plate (13) and the circulation regulating valve (14).

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