Method for controlling pressure in a calcium carbide furnace

Abstract

This invention discloses a method for controlling the furnace pressure of a calcium carbide furnace, comprising the following steps: S1: Inputting a preset furnace pressure value into the DCS controller, the DCS controller controls the frequency converters of the crude gas blower and the clean gas blower according to the set furnace pressure value; S2: Acquiring the pressure inside the calcium carbide furnace through a pressure transmitter and sending the acquired furnace pressure value signal to the DCS controller; S3: The DCS controller compares the furnace pressure value with the preset furnace pressure value and adjusts the frequency converters of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve; S4: Ensuring that the furnace pressure value is within the preset furnace pressure value range. By sending the furnace pressure acquired by the pressure transmitter to the DCS controller, thereby adjusting the frequency converters of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve, the method ensures that the furnace pressure remains within the normal operating range throughout the entire production process, ensuring normal production of the calcium carbide furnace and reducing the occurrence of safety accidents.

Description

Technical fields:

[0001] This invention relates to the field of calcium carbide production, specifically to a method for controlling the furnace pressure of a calcium carbide furnace. Background technology:

[0002] The calcium carbide furnace is the main equipment for producing calcium carbide. During production, prepared raw materials (lime and semi-coke) are added to the furnace. The furnace charge reacts at a high temperature of 1900–2200℃ using electric arc heat and resistance heat to produce calcium carbide (calcium carbide). This process also generates a large amount of furnace gas, whose main component is carbon monoxide, containing a small amount of dust. Therefore, the furnace gas needs to be purified. The furnace gas purification system also regulates the gas pressure inside the furnace. The furnace gas temperature is 500℃–800℃. It first undergoes preliminary cooling and dust removal through a water-cooled flue and cyclone separator to remove large dust particles and prevent them from settling and clogging the system in pipes or equipment. After reaching approximately 300-450℃, the gas enters the primary settling tank and is cooled in the secondary settling tank. The furnace gas is cooled to 200-260℃ by adjusting the cooling airflow. The cooled, undust-removed furnace gas is pressurized by a crude gas blower and then filtered by a bag filter. The filtered gas is then transported to the gas-fired kiln by a clean gas blower. The crude and clean gas blowers are mainly used to provide power for extracting the calcium carbide furnace gas. At the same time, the pressure of the calcium carbide furnace needs to be adjusted according to production requirements. If the pressure is too high, there will be flames coming out of the furnace cover, and carbon monoxide overflow will cause poisoning. If the pressure is too low (high negative pressure), it will cause air backflow, increasing the oxygen content in the calcium carbide furnace. This oxygen will react with carbon monoxide in the purification system and cause an explosion. Therefore, accurate control of the pressure inside the calcium carbide furnace is very important.

[0003] Currently, when adjusting the furnace pressure of a calcium carbide furnace, it is necessary to collect the internal pressure of the furnace through a pressure transmitter on the furnace top and send it to the DCS system. During normal production operation, the central control operator needs to adjust the frequency of the coarse air blower and the clean air blower according to the pressure value collected by the pressure transmitter to control the furnace pressure and keep it in a slightly positive pressure state (0-5Pa) to ensure normal production operation. However, in actual production, the furnace pressure changes very frequently. The central control operator can only continuously adjust the frequency of the coarse air blower and the clean air blower to control the furnace pressure. The entire operation process requires a high degree of concentration and is extremely labor-intensive. Moreover, if the furnace pressure cannot be adjusted quickly and in a timely manner, material spraying and collapse will occur, making the operation of the calcium carbide furnace highly dangerous and prone to safety accidents. Summary of the Invention:

[0004] The purpose of this invention is to provide a method for controlling the furnace pressure of a calcium carbide furnace.

[0005] This invention is implemented by the following technical solution:

[0006] A method for controlling the furnace pressure of a calcium carbide furnace includes the following steps:

[0007] S1: Input the furnace pressure preset value into the DCS controller. The DCS controller controls the frequency of the frequency converters of the crude gas blower and the clean gas blower according to the furnace pressure set value.

[0008] S2: The pressure inside the calcium carbide furnace is acquired through a pressure transmitter, and the acquired pressure value signal of the calcium carbide furnace is sent to the DCS controller.

[0009] S3: The DCS controller compares the pressure value inside the calcium carbide furnace obtained from S2 with the preset furnace pressure value input from S1, and adjusts the frequency converter frequency of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve.

[0010] S4: Ensures that the pressure value inside the calcium carbide furnace obtained by S2 is within the range of the preset furnace pressure value input by S1.

[0011] Preferably, after comparing the pressure value inside the calcium carbide furnace obtained in S2 with the preset furnace pressure value input in S1, if the pressure value inside the calcium carbide furnace obtained in S2 is higher than the preset furnace pressure value input in S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to increase the frequency.

[0012] If the pressure value inside the calcium carbide furnace obtained by S2 is lower than the preset furnace pressure value input by S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to reduce the frequency.

[0013] If the pressure value inside the calcium carbide furnace obtained by S2 is within the range of the furnace pressure preset value input by S1, the frequency of the inverters controlling the crude gas blower and the clean gas blower of the DSC controller remains unchanged.

[0014] Preferably, a clean gas storage tank is connected to the pipeline connecting the clean gas blower and the gas-fired kiln storage tank via a pressure relief pipe, and a pressure relief valve is installed on the pressure relief pipe; if the pressure value inside the calcium carbide furnace obtained in S2 is higher than the preset furnace pressure value input in S1 and is higher than 60Pa, the DSC controller controls the pressure relief valve to open until the pressure value inside the calcium carbide furnace obtained in S2 is within the preset furnace pressure value input in S1, and then the DSC controller controls the pressure relief valve to close.

[0015] Preferably, a pressure tapping pipe is connected to the furnace cover of the calcium carbide furnace, and an air vent valve is installed on the pressure tapping pipe; if the pressure value inside the calcium carbide furnace obtained by S2 is still higher than the preset furnace pressure value input by S1 and higher than 90Pa after the DSC controller controls the pressure relief valve to open for 2 seconds, the DSC controller controls the air vent valve to open until the pressure value inside the calcium carbide furnace obtained by S2 is within the preset furnace pressure value input by S1, and then the DSC controller controls the air vent valve to close.

[0016] Preferably, the frequency of the inverter of the crude gas blower is adjusted synchronously with the frequency of the inverter of the clean gas blower, and the frequency of the inverter of the crude gas blower is 2-5 Hz higher than that of the inverter of the clean gas blower.

[0017] Preferably, the frequency adjustment range of the inverters for the crude gas blower and the clean gas blower is 20-45Hz.

[0018] The advantages of this invention are: by transmitting the pressure of the calcium carbide furnace collected by the pressure transmitter to the DCS controller, the frequency of the frequency converters of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve, are adjusted to ensure that the pressure of the calcium carbide furnace is within the normal working range throughout the entire production process, thus ensuring normal production of the calcium carbide furnace, reducing the occurrence of safety accidents, and the entire process does not require constant attention from the central control operator, reducing the labor intensity of the central control operator. Attached image description:

[0019] Figure 1 This is a schematic diagram of the calcium carbide furnace gas purification system of the present invention;

[0020] Figure 2 This is the control principle diagram of the present invention. Detailed implementation method:

[0021] like Figure 1 and Figure 2 As shown, a method for controlling the furnace pressure of a calcium carbide furnace includes the following steps:

[0022] S1: Input the furnace pressure preset value into the DCS controller. The DCS controller controls the frequency of the frequency converters of the crude gas blower and the clean gas blower according to the furnace pressure set value.

[0023] S2: The pressure inside the calcium carbide furnace is acquired through a pressure transmitter, and the acquired pressure value signal of the calcium carbide furnace is sent to the DCS controller.

[0024] S3: The DCS controller compares the furnace pressure value obtained from S2 with the preset furnace pressure value input from S1, and adjusts the frequency converters of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve. After comparing the furnace pressure value obtained from S2 with the preset furnace pressure value input from S1, if the furnace pressure value obtained from S2 is higher than the preset furnace pressure value input from S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to increase their frequency; if the furnace pressure value obtained from S2 is lower than the preset furnace pressure value input from S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to decrease their frequency; if the furnace pressure value obtained from S2 is within the preset furnace pressure value input from S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to remain unchanged.

[0025] A clean gas storage tank is connected to the pipeline connecting the clean gas blower and the gas-fired kiln storage tank via a pressure relief pipe, and a pressure relief valve is installed on the pressure relief pipe; if the pressure value inside the calcium carbide furnace obtained by S2 is higher than the preset furnace pressure value input by S1 and is higher than 60Pa, the DSC controller controls the pressure relief valve to open until the pressure value inside the calcium carbide furnace obtained by S2 is within the preset furnace pressure value input by S1, and then the DSC controller controls the pressure relief valve to close.

[0026] A pressure tapping pipe is connected to the furnace cover of the calcium carbide furnace, and an air vent valve is installed on the pressure tapping pipe. If, after the DSC controller controls the pressure relief valve to open for 2 seconds, the pressure value inside the calcium carbide furnace obtained by S2 is still higher than the preset furnace pressure value input by S1 and higher than 90 Pa, the DSC controller controls the air vent valve to open until the pressure value inside the calcium carbide furnace obtained by S2 is within the preset furnace pressure value input by S1, and then the DSC controller controls the air vent valve to close.

[0027] S4: Ensures that the pressure value inside the calcium carbide furnace obtained by S2 is within the range of the preset furnace pressure value input by S1;

[0028] Taking the operation of a calcium carbide furnace as an example, the furnace pressure setpoint is manually input to the DSC central control system as 3Pa. Different PID control parameters are set for each furnace, and a control dead zone is introduced, with a range of ±3Pa (0~6Pa). Within this range, no frequency adjustment is performed. The DCS controls the frequency converters of the crude gas blower and the clean gas blower to 35Hz based on the furnace pressure setpoint. The pressure transmitter collects the furnace pressure value and sends it back to the DCS controller. If the furnace pressure is higher than 6Pa, the DSC controller increases the frequency of the crude gas blower and the clean gas blower; if the furnace pressure is lower than 0Pa, the DSC controller decreases the frequency; and if the furnace pressure is between 0 and 6Pa, the DSC controller keeps the frequency unchanged.

[0029] If the pressure inside the calcium carbide furnace is higher than 60 Pa, the DSC controller will open the pressure relief valve, and the furnace gas sent to the gas-fired kiln will be sent to the clean gas storage tank. Since the pressure in the clean gas storage tank is 0 Pa to 10 Pa, the pressure inside the calcium carbide furnace will drop rapidly until the pressure inside the calcium carbide furnace is between 0 Pa and 6 Pa, at which point the DSC controller will close the pressure relief valve.

[0030] If the pressure inside the calcium carbide furnace is still higher than 90 Pa after the DSC controller opens the pressure relief valve for 2 seconds, the DSC controller will open the vent valve. The gas in the calcium carbide furnace will then be quickly vented through the pressure tapping pipe, and the calcium carbide furnace will be rapidly depressurized until the pressure inside the calcium carbide furnace is between 0 and 6 Pa. At this point, the DSC controller will close the vent valve.

[0031] The frequency converter of the crude gas blower is adjusted synchronously with that of the clean gas blower, and the frequency converter of the crude gas blower is 2-5Hz higher than that of the clean gas blower. During the transportation of furnace gas in the calcium carbide furnace, the temperature drops from 500℃~800℃ to 200℃~260℃, and the pressure decreases throughout the process. Under the same model of blower, the gas flow rate in the calcium carbide furnace at the clean gas blower is faster, resulting in a decrease in pressure inside the calcium carbide furnace. Therefore, lowering the frequency converter of the clean gas blower by 2-5Hz can compensate for the decrease in pressure due to the temperature drop and ensure the stability of the furnace pressure.

[0032] The frequency adjustment range of the inverter for both crude gas blowers and clean gas blowers is 20-45Hz. Limiting the minimum frequency ensures that the blower can maintain a certain moment of rotational inertia and avoids the problem of slow start-up when the operating frequency is rapidly increased. At 45Hz, the blower motor is almost under maximum load. Limiting the maximum frequency can prevent the blower from operating under overload for a long time and ensure the service life of the blower.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the furnace pressure of a calcium carbide furnace, characterized in that, Includes the following steps: S1: Input the furnace pressure preset value into the DCS controller. The DCS controller controls the frequency of the frequency converters of the crude gas blower and the clean gas blower according to the furnace pressure set value. S2: The pressure inside the calcium carbide furnace is acquired through a pressure transmitter, and the acquired pressure value signal of the calcium carbide furnace is sent to the DCS controller. S3: The DCS controller compares the pressure value inside the calcium carbide furnace obtained from S2 with the preset furnace pressure value input from S1, and adjusts the frequency converter frequency of the crude gas blower and the clean gas blower, as well as the opening and closing of the vent valve and the pressure relief valve. After comparing the pressure value inside the calcium carbide furnace obtained by S2 with the preset furnace pressure value input by S1, if the pressure value inside the calcium carbide furnace obtained by S2 is higher than the preset furnace pressure value input by S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to increase the frequency. If the pressure value inside the calcium carbide furnace obtained by S2 is lower than the preset furnace pressure value input by S1, the DSC controller controls the frequency converters of the crude gas blower and the clean gas blower to reduce the frequency. If the pressure value inside the calcium carbide furnace obtained by S2 is within the range of the furnace pressure preset value input by S1, the frequency of the frequency converters of the crude gas blower and the clean gas blower controlled by the DSC controller remains unchanged. S4: Ensures that the pressure value inside the calcium carbide furnace obtained by S2 is within the range of the preset furnace pressure value input by S1; A clean gas storage tank is connected to the pipeline connecting the clean gas blower and the gas-fired kiln storage tank via a pressure relief pipe, and a pressure relief valve is installed on the pressure relief pipe; if the pressure value inside the calcium carbide furnace obtained by S2 is higher than the preset furnace pressure value input by S1 and is higher than 60Pa, the DSC controller controls the pressure relief valve to open until the pressure value inside the calcium carbide furnace obtained by S2 is within the preset furnace pressure value input by S1, and then the DSC controller controls the pressure relief valve to close. A pressure tapping pipe is connected to the furnace cover of the calcium carbide furnace, and an air vent valve is installed on the pressure tapping pipe. If, after the DSC controller controls the pressure relief valve to open for 2 seconds, the pressure value inside the calcium carbide furnace obtained by S2 is still higher than the preset furnace pressure value input by S1 and higher than 90 Pa, the DSC controller controls the air vent valve to open until the pressure value inside the calcium carbide furnace obtained by S2 is within the preset furnace pressure value input by S1, and then the DSC controller controls the air vent valve to close.

2. A method for controlling furnace pressure in a calcium carbide furnace according to any one of claims 1, characterized in that, The frequency of the inverter for the crude gas blower is adjusted synchronously with that of the inverter for the clean gas blower, and the frequency of the inverter for the crude gas blower is 2-5 Hz higher than that for the clean gas blower.

3. A method for controlling furnace pressure in a calcium carbide furnace according to any one of claims 1, characterized in that, The frequency adjustment range of the inverters for the crude gas blower and the clean gas blower is 20-45Hz.

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