Variable working condition anti-surge control method for coal compressor of dual-fuel gas turbine

Abstract

The invention relates to a variable working condition anti-surge control method for a dual-fuel gas turbine coal press, which comprises the following steps of: 1) automatically controlling a gas turbine control system (TCS) to meet the condition that (1) synthesis gas is put into operation, or the outlet pressure of a high-pressure coal press is not lower than 15bar; (2) the load of the gas turbine is less than 130MW, and the heat value of the synthesis gas is not less than 4050KJ / Kg, or the load set value of the gas turbine is not more than 90MW; (2) the gas turbine control system (TCS) is quitted for automatic control, and (1) the natural gas is prepared; (2) the synthesis gas is put into operation, or the outlet pressure of a high-pressure coal press is not lower than 15 bar; (3) the load of the gas turbine is not lower than 130MW, and the heat value of the synthesis gas does not exceed 3950KJ / Kg, or the load set value of the gas turbine is greater than 90MW; by means of the method, the working condition point of the coal gas pressurizing machine is close to the anti-surge line, the TCS participates in control over the return valve of the coal gas pressurizing machine, the conditions that the working condition point of the coal gas pressurizing machine jumps over the anti-surge line due to blast furnace gas pressure fluctuation, the anti-surge valve is rapidly opened, and the unit is shut down are prevented, and stable operation of the CCPP unit is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy and chemical engineering, and in particular to a variable operating condition anti-surge control method for a coal compressor of a dual-fuel combustion engine. Background Art

[0002] The existing CCPP generator sets include AE94.2KS low calorific value gas turbine combined cycle generator sets, in which the gas compressor adopts the axial flow (AV80-15) + centrifugal (RB90-6) solution produced by MAN. It is controlled by PLC and uses communication to transmit signals with the control system TCS of the gas turbine. In order to improve the operating efficiency of the gas compressor, the operating conditions of the high and low pressure gas compressors are close to the anti-surge line.

[0003] In actual operation, due to the large deviation between external working conditions and design, especially the large fluctuation of blast furnace gas pressure, when the blast furnace gas pressure suddenly decreases, the amount of coke oven gas mixed will increase, thereby increasing the calorific value of the synthesis gas entering the gas turbine. Since the gas turbine is operated at a constant power, the increase in calorific value will lead to a decrease in the flow rate of mixed gas entering the gas turbine. Under the operating conditions of high calorific value and low load of the gas turbine, the operating point of the gas compressor is close to the anti-surge line. The sudden decrease in the flow rate of mixed gas will cause the operating point of the gas compressor to jump over the anti-surge line, causing the gas compressor reflux valve to open quickly, causing the outlet pressure of the high-pressure gas to drop, and the gas turbine to shut down.

[0004] In order to ensure the stability of the operation of the gas turbine under high calorific value or low load conditions, the communication interface between the coal compressor control system PLC and the gas turbine control system TCS is used to control the input and output of the automatic control of the gas turbine control system TCS. Under the above conditions, TCS sends a control command to PLC to slowly open the return valve to keep the coal compressor operating point away from the anti-surge line to prevent the coal compressor operating point from jumping over the anti-surge line due to fluctuations in blast furnace gas pressure. At the same time, to ensure the economy of the gas turbine operation, after the gas turbine leaves the above conditions, TCS exits the adjustment of the return valve to ensure the operating efficiency of the coal compressor.

[0005] A Chinese patent with publication number CN102878100B discloses a control method for avoiding surge during normal shutdown of a single-shaft PTA compressor unit. By using a new programming method, the sequence and rate of shutdown actions are reasonably set during the normal shutdown of the unit to ensure safe and smooth shutdown of the unit. This control method effectively avoids the phenomenon of surge during normal shutdown of a single-shaft PTA compressor unit in series with a common vent pipeline, which causes an emergency shutdown due to excessive vibration interlock. At present, this method has been successfully put into operation at a certain PTA site, and it has been verified that this control scheme has a good effect on the normal shutdown control of the unit. This normal shutdown control method effectively avoids the phenomenon of surge during normal shutdown of the unit, which not only protects the unit, but also brings huge economic benefits to users. However, the patent mentions the method of anti-surge control during normal shutdown, and does not consider the anti-surge adjustment means under various working conditions such as startup, normal operation, medium density change, and load change. Summary of the invention

[0006] The present invention provides a dual-fuel gas turbine coal compressor variable operating condition anti-surge control method. Under certain operating conditions of the CCPP unit, the gas compressor operating point is close to the anti-surge line. The gas turbine control system TCS participates in the control of the gas compressor return valve to prevent the coal compressor operating point from jumping over the anti-surge line due to blast furnace gas pressure fluctuations, causing the anti-surge valve to open quickly, causing the unit to shut down, thereby ensuring stable operation of the CCPP unit.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A dual-fuel combustion engine coal compressor variable operating condition anti-surge control method, comprising:

[0009] 1) The TCS automatic control of the gas turbine control system meets the following conditions:

[0010] (1) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar;

[0011] (2) The gas turbine load is less than 130MW and the calorific value of the synthesis gas is not less than 4050KJ / Kg, or the gas turbine load setting value does not exceed 90MW;

[0012] 2) Exit the gas turbine control system TCS automatic control to meet the following conditions:

[0013] (1) Natural gas is ready;

[0014] (2) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar;

[0015] (3) The gas turbine load is not less than 130MW and the calorific value of the synthesis gas does not exceed 3950KJ / Kg, or the gas turbine load setting value is greater than 90MW.

[0016] Furthermore, the said starting the gas turbine control system TCS automatic control or exiting the gas turbine control system TCS automatic control adopts the rising edge of the automatic starting / exiting signal changing from 0 to 1 as the starting / exiting triggering instruction.

[0017] Furthermore, the gas turbine control system TCS is automatically controlled to control the opening of the gas compressor return valve.

[0018] Furthermore, the exit of the gas turbine control system TCS automatic control does not participate in the control of the high and low pressure coal compressor return valves.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) By controlling the TCS automatic control of the gas turbine control system to start or stop, the opening degree of the coal compressor return valve can be automatically controlled to ensure the operating stability of the gas turbine under high calorific value and low load conditions, expand the operating range of the gas turbine unit, and ensure that the unit can operate stably under conditions beyond the design conditions;

[0021] 2) It is of great significance to the overall gas balance on site, reduce gas emission and improve the utilization rate of secondary energy;

[0022] 3) It has greatly improved the operating stability of the CCPP unit, basically eliminated the occurrence of unit shutdowns due to the coal compressor operating point jumping over the anti-surge line, and greatly reduced the number of CCPP unit failure shutdowns. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the automatic control logic block diagram of the TCS control system of the gas turbine described in the present invention.

[0024] Figure 2 It is the automatic control logic block diagram of the TCS automatic control system for exiting the gas turbine control system described in the present invention.

[0025] Figure 3 It is a schematic diagram of the constant pressure operation of the coal compressor and the safety margin adjustment of the anti-surge line according to the present invention. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0027] The present invention provides a dual-fuel combustion engine coal compressor variable operating condition anti-surge control method, comprising:

[0028] 1) The TCS automatic control of the gas turbine control system meets the following conditions:

[0029] (1) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar: This automatic control should take effect after the fuel switch is completed when the gas turbine is started, so the synthesis gas is put into operation as a prerequisite for the judgment of the start-up. At the same time, considering the fact that the working point of the coal compressor jumps over the anti-surge line during the pressure increase of the gas compressor when the gas turbine is started, causing the outlet pressure of the coal compressor to fluctuate greatly and cause the start-up failure, the outlet pressure of the high-pressure coal compressor is selected to be not less than 15 bar;

[0030] (2) The gas turbine load is less than 130MW and the calorific value of the synthesis gas is not less than 4050KJ / Kg, or the gas turbine load setting value does not exceed 90MW: Considering that the gas turbine should be put into automatic operation only under the highest load operating condition, it is determined that the gas turbine load is less than 130MW. According to the actual operating conditions of the gas turbine, when the gas turbine is running at full load and the calorific value of the synthesis gas is not less than 4050KJ / Kg, the coal compressor operating point is close to the anti-surge line, and when the gas turbine is running within the rated calorific value range and the gas turbine load setting value does not exceed 90MW, the coal compressor operating point is also close to the anti-surge line;

[0031] See Figure 1 , the logic of TCS automatic control of the gas turbine control system is:

[0032] (High-pressure coal compressor outlet pressure ≥ 15 bar OR synthesis gas is put into operation) AND ((fuel engine load < 130MW AND synthesis gas calorific value ≥ 4050KJ / Kg) OR fuel engine load setting value ≤ 90MW);

[0033] That is: when the outlet pressure of the high-pressure coal compressor is ≥15bar or the synthesis gas is put into operation, when (the gas turbine load is <130MW and the calorific value of the synthesis gas is ≥4050KJ / Kg) or the gas turbine load setting value is ≤90MW, an automatic start-up trigger command is issued, and the gas turbine control system TCS automatically controls the start-up and participates in the control of the high and low pressure coal compressor return valves, thereby controlling the opening of the gas compressor return valve.

[0034] 2) Exit the gas turbine control system TCS automatic control to meet the following conditions:

[0035] (1) Natural gas ready: When the CCPP unit is started, the gas turbine control system TCS automatic control needs to be in the exit automatic state, and natural gas ready is selected as the prerequisite for exit;

[0036] (2) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar;

[0037] (3) The gas turbine load is not less than 130MW and the calorific value of the synthesis gas does not exceed 3950KJ / Kg, or the gas turbine load setting value is greater than 90MW.

[0038] See Figure 2 , exit the gas turbine control system TCS automatic control logic is:

[0039] Natural gas is ready OR ((high pressure coal compressor outlet pressure ≥ 15 bar OR synthesis gas is put into operation) AND (gas turbine load ≥ 130MW or synthesis gas calorific value ≤ 3950KJ / Kg) AND gas turbine load setting value > 90MW);

[0040] That is: when the natural gas is ready or when the outlet pressure of the high-pressure coal compressor is ≥15bar or the synthesis gas is put into operation, when (the gas turbine load is ≥130MW or the calorific value of the synthesis gas is ≤3950KJ / Kg) and the gas turbine load setting value is >90MW, an automatic exit command is issued, and the gas turbine control system TCS automatically exits and does not participate in the control of the high and low pressure coal compressor return valves.

[0041] In order to prevent the relevant judgment conditions from fluctuating around the threshold value, causing the automatic start / stop of the gas turbine control system TCS to fluctuate back and forth, the rising edge of the automatic start / stop signal from 0 to 1 is used as the trigger instruction for start / stop.

[0042] See Figure 3 The TCS automatic control system of the gas turbine control system will control the opening of the gas compressor return valve, so that the distance between the low-pressure coal compressor operating point and the anti-surge line is maintained at about -9%; the distance between the high-pressure coal compressor operating point and the anti-surge line is about -11%.

[0043] The above embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A dual-fuel combustion engine coal compressor variable operating condition anti-surge control method, characterized in that: include: 1) The TCS automatic control of the gas turbine control system meets the following conditions: (1) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar; (2) The gas turbine load is less than 130MW and the calorific value of the synthesis gas is not less than 4050KJ / Kg, or the gas turbine load setting value does not exceed 90MW; 2) Exit the gas turbine control system TCS automatic control to meet the following conditions: (1) Natural gas is ready; (2) Synthesis gas is put into operation, or the outlet pressure of the high-pressure coal compressor is not less than 15 bar; (3) The gas turbine load is not less than 130MW and the calorific value of the synthesis gas does not exceed 3950KJ / Kg, or the gas turbine load setting value is greater than 90MW.

2. A dual-fuel gas turbine coal compressor variable operating condition anti-surge control method according to claim 1, characterized in that: The said starting or exiting the TCS automatic control of the gas turbine control system adopts the rising edge of the automatic starting / exiting signal changing from 0 to 1 as the triggering instruction for starting / exiting.

3. A dual-fuel gas turbine coal compressor variable operating condition anti-surge control method according to claim 1, characterized in that: The input gas turbine control system TCS automatically controls the opening of the gas compressor return valve.

4. A dual-fuel gas turbine coal compressor variable operating condition anti-surge control method according to claim 3, characterized in that: The exit from the gas turbine control system TCS automatic control does not participate in the control of the high and low pressure coal compressor return valves.

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