Sewage Discharge Method of a Sewage Discharge Device for a Double-Chamber Balanced Liquid Level Gauge

Abstract

The present invention is a sewage discharge device for a double-chamber balanced liquid level gauge, comprising: a balance chamber; a liquid phase conduit connected to the bottom of the steam drum, with its first end vertically arranged in the balance chamber and its second end provided with a second sewage discharge port; a vapor phase conduit connecting the balance chamber and the top of the steam drum; a sewage discharge pipe arranged at the bottom of the balance chamber, with its first end provided with a first sewage discharge port; a drain pipe, one end of which is connected to the top of the balance chamber and the other end is communicated with the atmosphere; a first electric sewage discharge valve arranged at the first sewage discharge port; a second electric sewage discharge valve arranged at the second sewage discharge port; a first electric valve arranged at the vapor phase conduit; a second electric valve arranged at the drain pipe; The present solution has the following advantages: 1. Automatic sewage discharge is realized, reducing the damage caused by manual valves due to long-term non-use; 2. When discharging sewage from the same type of liquid level gauge, the inaccuracy of the measured liquid level caused by the change of the liquid level in the standard chamber is avoided; thereby improving the reliability of the steam drum liquid level monitoring.

Description

Technical Field

[0001] The present invention relates to a double-chamber balanced liquid level gauge, in particular to a sewage discharge method for a sewage discharge device of a double-chamber balanced liquid level gauge. Background Art

[0002] The circulation of water in the vaporization cooling system takes away the heat generated by the combustion of the furnace in the furnace diameter tube, and at the same time cools the water beam in the furnace; the heat in the furnace is very high, up to 1000 °C all year round; so when the water circulating in the vaporization cooling system passes through the steam drum midway, the inside of the steam drum is in a state where water and steam coexist; the pressure is normally controlled at 8-10 BAR, the maximum is 12 BAR, and the limit is 16 BAR;

[0003] The normal state in the steam drum is that the lower part is water (liquid) and the upper part is gas; and the steam generated under the action of the furnace heat will continuously be transported to the external steam network; the steam generated by the heating furnace is recovered; the ratio of the recovered steam volume to the makeup water volume into the vaporization cooling system is the steam-water ratio, which is an important index; if the water level in the steam drum is too high, it may inject water into the external steam network, and it may also cause the pressure to be too high to blow open the safety valve due to continuous water addition, which is very dangerous; if the water level in the steam drum is too low, it means that the water in the system is about to evaporate completely, and at this time the cooling effect of the circulating water on the water beam drops sharply, which will cause the risk of the furnace collapsing, which is extremely dangerous; so it is very important to monitor the steam drum liquid level under normal working conditions.

[0004] Structural principle of the double-chamber balanced liquid level gauge: Under normal circumstances, the water level in the boiler steam drum cannot be directly measured, so the extraction pipe measurement method is mostly used; but its drawback is that the temperature difference between the extraction pipe and the steam drum is large; therefore, the density difference of water will cause some measurement errors; using a double-chamber balanced container can effectively use the condensation of saturated steam to heat the liquid phase conduit and the balance chamber in the balanced container; and the entire balanced container has enough protective layers to reduce heat loss; so that the temperature of the balanced container is close to the temperature inside the steam drum; thus making the differential pressure detection more accurate; the water level in the balance chamber is used as a reference; the change in differential pressure is linearly related to the liquid level height in the liquid phase conduit.

[0005] During the long-term use of the steam drum liquid level gauge, water stains and dirt will be generated; because the steam drum liquid level gauge has not been drained for a long time and the detection pipe is blocked, resulting in a low displayed liquid level; in the automatic makeup water state, the feed pump keeps adding water, causing the safety valve at the top of the steam drum to burst and the entire vaporization system to relieve pressure; fortunately, it was discovered in time and no more terrible accidents occurred; later, it was found that there are three problems with the sewage discharge of the on-site steam drum liquid level gauge:

[0006] 1. The on-site personnel often forget to manually drain the sewage;

[0007] 2. The manual sewage discharge valve has no periodic action and often gets blocked, eventually causing stains to be unable to be discharged.

[0008] 3. After each manual sewage discharge, the display value of the liquid level gauge becomes completely incorrect and must wait for 2 to 6 hours to return to normal.

[0009] In summary, how to achieve automatic sewage discharge of the double-chamber balanced liquid level gauge and obtain the liquid level height in the steam drum timely and accurately after sewage discharge has become an urgent problem to be solved by researchers in this field. Summary of the Invention

[0010] The technical problem to be solved by the present invention is: how to achieve automatic sewage discharge of the double-chamber balanced liquid level gauge and obtain the liquid level height in the steam drum timely and accurately after sewage discharge.

[0011] To solve the above technical problem, the technical solution adopted by the present invention is:

[0012] The present invention is a sewage discharge device for a double-chamber balanced liquid level gauge, including: a balance chamber; a liquid phase conduit connecting the bottom of the steam drum, with its first end vertically arranged in the balance chamber and its second end provided with a second sewage discharge port; a vapor phase conduit connecting the balance chamber and the top of the steam drum; a sewage discharge pipe arranged at the bottom of the balance chamber, with its first end provided with a first sewage discharge port; a drain pipe, one end of which is connected to the top of the balance chamber and the other end is communicated with the atmosphere; a first electric sewage discharge valve arranged at the first sewage discharge port; a second electric sewage discharge valve arranged at the second sewage discharge port; a first electric valve arranged at the vapor phase conduit; a second electric valve arranged at the drain pipe.

[0013] Further, the liquid phase conduit has a third end, and the third end of the liquid phase conduit is connected to a differential pressure transmitter; the sewage discharge pipe has a second end, and the second end of the sewage discharge pipe is connected to the differential pressure transmitter.

[0014] Further, a first manual valve is arranged on the vapor phase conduit; a second manual valve is arranged on the liquid phase conduit and at the outlet of the steam drum; a third manual valve is arranged on the sewage discharge pipe; a fourth manual valve is arranged on the liquid phase conduit and is adapted to control whether the liquid enters the second end and the third end of the liquid phase conduit; a fifth manual valve is arranged on the drain pipe.

[0015] To specifically illustrate the sewage discharge method of this solution, the present invention adopts the following steps: S1: Open the first electric sewage discharge valve, the second electric sewage discharge valve, and the second electric valve; close the first electric valve; at this time, the gas in the steam drum will not enter the balance chamber; S2: The liquid is mixed with the balance liquid and fills the balance chamber, and is discharged through the drain pipe, the second electric sewage discharge valve, and the first electric sewage discharge valve for sewage discharge; S3: After several seconds of sewage discharge, close the first electric sewage discharge valve, the second electric sewage discharge valve, and the second electric valve, and open the first electric valve to complete the sewage discharge.

[0016] Furthermore, during the sewage discharge process, the first manual valve, the second manual valve, the third manual valve, the fourth manual valve, and the fifth manual valve are all in the normally open state.

[0017] The beneficial effects of the present invention: The present invention is a sewage discharge method for a sewage discharge device of a double-chamber balanced liquid level gauge. This solution has the following advantages:

[0018] 1. Realize automatic sewage discharge and reduce the damage caused by manual valves due to long-term disuse.

[0019] 2. Avoid inaccurate measured liquid levels caused by changes in the liquid level of the standard chamber during sewage discharge of the same type of liquid level gauge; thereby improving the reliability of steam drum liquid level monitoring. Description of the Drawings

[0020] The present invention will be further described below in conjunction with the drawings and embodiments.

[0021] Figure 1 is the structural schematic diagram before improvement;

[0022] Figure 2 is the structural schematic diagram after improvement. Detailed Embodiments

[0023] Now, the present invention will be further described in detail in conjunction with the drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so they only show the components related to the present invention.

[0024] As Figure 1It is a schematic diagram of the working principle of a traditional drum level gauge; first, the level feedback is the value generated by the differential pressure transmitter 1 and sent to the PLC for calculation and display on the monitoring screen; the differential pressure transmitter 1 calculates the pressure difference between the two input pipes, the drain pipe 3 and the liquid phase conduit 2 to determine the actual level; the drain pipe 3 detects the pressure of the water in the equilibrium chamber 4 and calibrates the highest level of the drum level gauge based on this pressure (for example: 320MM); the liquid level in the liquid phase conduit 2 in the equilibrium chamber 4 is the same as the liquid level inside the drum 5; the change in the actual liquid level in the drum 5 will cause the change in the water level in the liquid phase conduit 2, and according to the different changes in the water level height, the pressure generated by the water level on the liquid phase conduit 2 side is also different; the level is calculated based on the pressure difference between the drain pipe 3 and the liquid phase conduit 2.

[0025] There is a plug 6 above the equilibrium chamber 4, which is blocked under normal conditions; the plug 6 can be removed to fill the equilibrium chamber 4 with water when both the first hand valve 7 and the second hand valve 8 are closed; this operation can also be carried out in the initial state before the drum 5 is put into use, and the purpose is to fill the equilibrium chamber 5 with water, so that the pressure of the drain pipe 3 remains constant all the time and can be used as a reference to judge the actual liquid level in the drum 5; when the level gauge is working normally, the first hand valve 7, the second hand valve 8, the third hand valve 9, and the fourth hand valve 10 are all open, and the first drain valve 11 and the second drain valve 12 are closed; when this state is maintained for a long time, the water in the part of the pipeline below the differential pressure transmitter 1 does not flow, the deposition of the chemical agent in the water (chemical agent is added to the circulating soft water), and factors such as the corrosion inside the pipe will cause blockage starting from the first and second drain valves 11 and 12 upwards, and finally blockage to the T-shaped corner above the first and second drain valves 11 and 12; resulting in abnormal measurement of the double-chamber equilibrium level gauge.

[0026] According to the above description, it can be known that the drum level gauge must be drained regularly. If not, it will surely cause abnormal liquid level detection of the drum level gauge. Generally, the first drain valve 11 and the second drain valve 12 are manually opened for 10 - 30 seconds until the drained water is clearly visible to the naked eye. When the second drain valve 12 drains water, it will cause a slight change in the liquid level of the liquid phase conduit 2 of the drum, which is almost negligible. Moreover, at this time, the level gauge can immediately resume feedback on the actual liquid level of the drum when the second drain valve 12 is closed. During the opening of the second drain valve 12, there is pressure relief in the liquid phase conduit 2, and the displayed liquid level is also inaccurate at this time. Similarly, after the first drain valve 11 is opened, the drain pipe 3 starts to drain. When the first drain valve 11 is opened, it will also cause pressure relief in the drain pipe 3, and the displayed liquid level is also inaccurate at this time. After the drain pipe 3 drains, the liquid level in the equilibrium chamber 4 will drop. This will cause a change in the standard pressure value on the drain pipe 3 side of the differential pressure transmitter 1. This change will cause the displayed liquid level value to be abnormally high. This is also the reason why the liquid level display value becomes inaccurate after draining. The reason is that the equilibrium liquid level in the equilibrium chamber 4 drops due to draining, resulting in a decrease in the standard liquid level. After the standard liquid level drops, the steam in the upper part of the drum 5 passes through the first manual valve 7 and then condenses in the equilibrium chamber 4. Usually, it takes 2 - 6 hours to fill the equilibrium liquid level in the equilibrium chamber 4 to the standard position. Therefore, the liquid level display is inaccurate for some time after each draining, and manual monitoring is required. As the awareness of the importance of the vaporization system by the on-site workers continues to deepen, this situation where the drum liquid level cannot be monitored in real time often makes people very uneasy. This situation has further increased the urgency of the on-site workers' requirements for abnormal-free draining.

[0027] Such as Figure 2 , Figure 2 is the schematic diagram of the improved draining of the drum level gauge; Figure 1 With the valve markings in unchanged, mainly a first electric valve 13 is added behind the first manual valve 7; a first electric drain valve 14 and a second electric drain valve 15 are added behind the first and second drain valves 11 and 12 respectively; a new pipeline is added at the outlet of the plug 6 as a drain pipe 16, and a fifth manual valve 17 and a second electric valve 18 are added to the drain pipe 16. In this way, automatic regular draining can be achieved, and the drum level gauge can still accurately feedback the true liquid level after draining.

[0028] Working principle:

[0029] Normal working state before sewage discharge: the first manual valve 7, the second manual valve 8, the third manual valve 9, and the fourth manual valve 10 remain normally open as before; the first sewage valve 11 and the second sewage valve 12 are changed to normally open; the fifth manual valve 17 is normally open; the first electric valve 13 is normally open, and the second electric valve 18, the first electric sewage valve 14, and the second electric sewage valve 15 are closed; the control of all electric valves is controlled by the output relay driven by the PLC; at this time, the closing of the second electric valve 18 replaces the function of the original plug 6; the closing of the first electric sewage valve 14 and the second electric sewage valve 15 replaces the closing of the original first sewage valve 11 and the second sewage valve 12; in this way, the improved working state is consistent with the original one; it can normally feedback and display the real liquid level of the steam drum;

[0030] That is, when the dual-chamber balancing liquid level gauge is working normally, balancing liquid is injected into the balancing chamber 4; the first electric drain valve 14, the second electric drain valve 15, and the second electric valve 18 are closed; the first electric valve 13 is opened; the liquid enters the first end of the liquid phase conduit 2 through the liquid phase conduit 2, and the gas enters the balancing chamber 4 through the gas phase conduit 19; the liquid level height in the steam drum 5 is determined by the liquid level height at the first end of the liquid phase conduit 2.

[0031] Working state during sewage discharge: the manual valves remain unchanged; the first electric valve 13 is closed to prepare for sewage discharge; after 5 seconds, the second electric valve 18, the first electric sewage valve 14, and the second electric sewage valve 15 are opened to discharge sewage; the sewage discharge time is about 5 seconds; because the sewage discharge is periodically controlled by the PLC, the sewage discharge time does not need to be too long each time; when the first electric valve 13 is closed, the balancing chamber is cut off by the pressure from the gas, and the liquid will pass through the second manual valve 8 and then through the liquid phase conduit 2 to the first end until it fills the entire balancing chamber 4 and reaches the second electric valve 18; at this time, the liquid in the liquid phase conduit 2 and the balancing liquid in the balancing chamber 4 are merged into one and are at the same pressure. This pressure is provided by the liquid phase conduit of the steam drum 5 through the second manual valve 8; then after 5 seconds, the second electric valve 18, the first electric sewage valve 14, and the second electric sewage valve 15 are opened again; it is equivalent to a pressurized water body having three outlets at the same time, and the three outlets will discharge water at the same time; during the drainage process, the entire balancing chamber 4 will be filled with water.

[0032] Working state after sewage discharge: all manual valves remain unchanged, and the electric valve returns to normal working state; during the sewage discharge process, the water filled in the balancing chamber 4 will be re-supported by the pressure of the steam drum 5, and the part of the water in the balancing chamber 4 that is higher than the standard water level will flow back into the steam drum 5 through the first electric valve 13 and the first manual valve 7 (steam phase conduit 19), thereby returning the water level in the balancing chamber 4 to the standard liquid level; and the steam in the steam drum 5 can also pass through the first manual valve 7 and the first electric valve 13 to the upper part of the balancing chamber 4; so that the water level collected by the liquid phase conduit 2 in the balancing chamber 4 and the steam drum are kept at the same height; at this time, the steam drum liquid level gauge can accurately reflect the actual liquid level of the steam drum, avoiding the need for water vapor condensation to supplement the standard liquid level.

[0033] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A sewage discharge method for a sewage discharge device of a double-chamber balanced liquid level gauge, the sewage discharge device comprising: Balancing chamber; Liquid-phase conduit, which is connected to the bottom of the steam drum, with its first end vertically arranged in the balancing chamber and its second end provided with a second blowdown port; Vapor-phase conduit, which is connected to the balancing chamber and the top of the steam drum; blowdown pipe, which is arranged at the bottom of the balancing chamber, with its first end provided with a first blowdown port; drain pipe, one end of which is connected to the top of the balancing chamber and the other end is communicated with the atmosphere; first electric blowdown valve, which is arranged at the first blowdown port; second electric blowdown valve, which is arranged at the second blowdown port; first electric valve, which is arranged at the vapor-phase conduit; second electric valve, which is arranged at the drain pipe, and is characterized by the following steps: S1: The first electric blowdown valve, the second electric blowdown valve and the second electric valve are opened; the first electric valve is closed; at this time, the steam in the steam drum will not enter the balancing chamber; S2: The liquid is mixed with the balancing liquid and fills the balancing chamber, and is discharged through the drain pipe, the second electric blowdown valve and the first electric blowdown valve for blowdown; S3: After several seconds of completing the blowdown, the first electric blowdown valve, the second electric blowdown valve and the second electric valve are closed, and the first electric valve is opened to complete the blowdown.

2. The sewage discharge method of a sewage discharge device for a two-chamber balanced liquid level gauge according to claim 1, characterized in that, The liquid-phase conduit has a third end, and the third end of the liquid-phase conduit is connected to a differential pressure transmitter; The blowdown pipe has a second end, and the second end of the blowdown pipe is connected to the differential pressure transmitter.

3. The sewage discharge method of a sewage discharge device for a double-chamber balanced liquid level gauge according to claim 1, characterized in that, A first manual valve is arranged on the vapor-phase conduit; On the liquid-phase conduit and at the outlet of the steam drum, a second manual valve is arranged; A third manual valve is arranged on the blowdown pipe; A fourth manual valve is arranged on the liquid-phase conduit, which is suitable for controlling whether the liquid enters the second end and the third end of the liquid-phase conduit; A fifth manual valve is arranged on the drain pipe.

4. The sewage discharge method of a sewage discharge device for a two-chamber balanced liquid level gauge according to claim 3, characterized in that, During the blowdown process, the first manual valve, the second manual valve, the third manual valve, the fourth manual valve and the fifth manual valve are all in the normally open state.

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