Boiler tail heating surface wall temperature adjusting device

Abstract

The utility model discloses a boiler tail heating surface wall temperature adjusting device. A first-stage water mixer, a second-stage water mixer, a water feeding pump and a coal economizer are sequentially arranged on a low-pressure water feeding pipeline of the boiler tail heating surface wall temperature adjusting device. The economizer is connected with a steam pocket through a pipeline; a high-temperature water pipe is connected to the coal economizer steam drum removing pipeline through a tee joint, and the high-temperature water pipe is in pipeline connection with a first-stage water mixer; and the second-stage water mixer is connected with external steam through a steam pipeline. The device is simple in structure and convenient to assemble, operation of an original system is not affected by transformation, automatic adjustment is achieved, the service life of a tail heating surface is prolonged, and safety and economical efficiency of the boiler are improved.

Description

Technical Field

[0001] This utility model relates to the field of boilers, and in particular to a boiler tail heating surface wall temperature regulating device. Background Technology

[0002] Currently, flue gas from the combustion of sulfur-containing fuels and flue gas from waste heat boilers contain corrosive gases, commonly carbon dioxide, sulfur dioxide, and sulfur trioxide. Taking a calcining furnace as an example, the sulfur dioxide content in the flue gas is 0.15%. Sulfur dioxide is further oxidized to sulfur trioxide under the action of a catalyst. In waste heat boiler calculations, sulfur trioxide is usually taken as 0.1 times the concentration of sulfur dioxide. By referring to relevant linear calculation tables, the acid dew point temperature is estimated to be 140℃.

[0003] Therefore, the presence of sulfur trioxide significantly increases the dew point of the flue gas, meaning condensation will form even at higher temperatures. Once condensed, it combines with sulfur trioxide to form sulfuric acid, causing acid corrosion on the metal walls. Furthermore, when the boiler load is low, the flue gas temperature also decreases, exacerbating low-temperature corrosion of the economizer tubes. Acid corrosion will not form when the wall temperature of the boiler's tail-end heating surface is above the dew point. Traditional methods include using corrosion-resistant metal materials, heat pipe heat exchangers, and applying corrosion-resistant coatings to the metal exterior. However, these methods are costly and often result in localized damage during use. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a boiler tail heating surface wall temperature regulating device that can effectively increase the wall temperature of the heating surface, reduce corrosion, and improve the service life and safety performance of the equipment through adjustment.

[0005] The equipment includes a low-pressure water supply pipe, on which a first-stage mixer, a second-stage mixer, a water supply pump, and an economizer are sequentially installed; the economizer pipe is connected to the steam drum.

[0006] A bypass pipe is connected across the low-pressure water supply pipe between the first-stage mixer and the second-stage mixer and the water supply pump; a bypass valve is installed on the bypass pipe.

[0007] A high-temperature water pipe is connected to the economizer to the steam drum via a tee, and the high-temperature water pipe is connected to the first-stage mixer; and a high-temperature water flow meter and a high-temperature water regulating valve are sequentially installed on the high-temperature water pipe.

[0008] The two-stage mixer is connected to external steam via a steam pipe, and a steam regulating valve is installed on the steam pipe.

[0009] A temperature measuring mechanism is also installed between the water pump and the economizer.

[0010] The effect achieved is that when the flue gas contains corrosive gases, to ensure that the outer wall temperature of the economizer's heating surface is above the flue gas dew point, the water temperature entering the economizer needs to be increased. At this time, the bypass valve is closed, and the opening of the high-temperature water regulating valve is opened and adjusted. The high-temperature feedwater entering the steam drum from the economizer is diverted into the high-temperature water pipe, passing sequentially through the high-temperature water flow meter and the high-temperature water regulating valve before entering the first-stage mixer to mix with the low-pressure feedwater, thus increasing the feedwater temperature. When it is necessary to further increase the feedwater temperature, the second-stage mixer is activated. The second-stage mixer is heated by steam; the steam enters the second-stage mixer through the steam regulating valve and mixes with the water from the first-stage mixer to further increase the feedwater temperature. Then, it enters the feedwater pump through the pre-pump, and finally passes through the economizer into the steam drum.

[0011] The beneficial effects of this utility model are: by adjusting the feedwater temperature, the metal wall temperature is increased to be higher than the dew point temperature, thus avoiding dew point corrosion on the boiler tail heating surface, thereby extending the service life of the tail heating surface, and greatly improving the safety and economy of the equipment. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of a boiler tail heating surface wall temperature regulating device according to the present invention;

[0013] Figure 2 This is a control logic diagram of a boiler tail heating surface wall temperature regulating device according to the present invention;

[0014] Figure label:

[0015] 1-Low-pressure water supply pipe; 2-Stage 1 mixer; 3-Stage 2 mixer; 4-Pre-pump; 5-Water supply pump; 6-Temperature measuring mechanism; 7-Economizer; 8-Steam drum; 9-High-temperature water flow meter; 10-High-temperature water regulating valve; 11-Steam pipe; 12-Steam regulating valve; 13-Bypass pipe; 14-Bypass valve

[0016] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] Reference Figure 1 , Figure 2 The present invention provides a boiler tail heating surface wall temperature regulating device, comprising a low-pressure feedwater pipe 1, wherein a first-stage mixer 2, a second-stage mixer 3, a feedwater pump 5 and an economizer 7 are sequentially arranged on the low-pressure feedwater pipe 1; the economizer 7 is connected to a steam drum 8.

[0018] Between the first-stage mixer 2 and the second-stage mixer 3 and the water supply pump 5, a bypass pipe 13 is connected across the low-pressure water supply pipe 1; a bypass valve 14 is installed on the bypass pipe 13.

[0019] A high-temperature water pipe is connected to the economizer 7 to the steam drum 8 via a tee, and the high-temperature water pipe is connected to the first-stage mixer 2; and a high-temperature water flow meter 9 and a high-temperature water regulating valve 10 are sequentially installed on the high-temperature water pipe.

[0020] The second-stage mixer 3 is connected to external steam via a steam pipe 11, and a steam regulating valve 12 is installed on the steam pipe 11.

[0021] A temperature measuring mechanism 6 is also provided between the water pump 5 and the economizer 7.

[0022] The effect achieved is that when the flue gas contains corrosive gases, in order to ensure that the outer wall temperature of the heated surface of the economizer 7 is above the flue gas dew point, the water temperature entering the economizer 7 needs to be increased. At this time, the bypass valve 14 is closed, and the opening of the high-temperature water regulating valve 10 is opened and adjusted. The high-temperature feedwater entering the steam drum 8 from the economizer 7 is diverted and enters the high-temperature water pipe, passing through the high-temperature water flow meter 9 and the high-temperature water regulating valve 10 in sequence, and then enters the first-stage mixer 2 to mix with the low-pressure feedwater, thereby increasing the feedwater temperature. When it is necessary to further increase the feedwater temperature, the second-stage mixer 3 is activated. The second-stage mixer 3 is heated by steam. The steam enters the second-stage mixer 3 through the steam regulating valve 12 and mixes with the water coming out of the first-stage mixer 2 to further increase the feedwater temperature. Then, it enters the feedwater pump 5 through the pre-pump 4, and then enters the steam drum 8 through the economizer 7.

[0023] Furthermore, a pre-pump 4 is also installed on the low-pressure water supply pipe 1 between the second-stage mixer 3 and the water supply pump 5.

[0024] The pre-pump 4 is used to prevent cavitation in the feedwater pump 5 and ensure its stability. A temperature measuring mechanism 6 is installed at the inlet of the feedwater pump 5 to serve as a reference for adjusting the water temperature.

[0025] Furthermore, the diameter of the high-temperature water pipe is half the diameter of the low-pressure water supply pipe 1.

[0026] Furthermore, the boiler tail heating surface wall temperature regulating device is controlled in conjunction with a processor;

[0027] The temperature measuring mechanism 6 and the flow meter are respectively connected to the processor via transmitter signals; the processor is connected to the execution unit, and the execution unit is connected to the steam regulating valve 12, the bypass valve 14 and the high-temperature water regulating valve 10.

[0028] The processor is also equipped with an input panel for signal connection.

[0029] The working principle of this utility model is as follows:

[0030] A bypass pipe 13 is connected to the low-pressure water supply pipe at the inlet of stage 1 mixer 2 and the water supply pipe at the outlet of pre-pump 4. A bypass valve 14 is installed on the bypass pipe 13. A high-temperature water pipe is connected to the water supply pipe at the outlet of economizer 7. A high-temperature water flow meter 9 and a high-temperature water regulating valve 10 are installed on the high-temperature water pipe. The outlet of the high-temperature water pipe is connected to stage 1 mixer 2. The outlet of stage 1 mixer 2 is connected to the inlet of stage 2 mixer 3. Stage 2 mixer 3 is connected to steam regulating valve 12 through a pipe. The outlet of stage 2 mixer 3 enters the inlet of pre-pump 4. The outlet of pre-pump 4 is connected to the inlet of feed pump 5. The outlet of feed pump 5 enters economizer 7 through a high-pressure feed pipe. A temperature measuring device 6 is installed on the high-pressure feed pipe.

[0031] When the bypass valve 14 is open and the high-temperature water regulating valve 10 is closed, the boiler does not change its original structure and continues to operate according to the original system water supply method. At this time, low-pressure feedwater enters the feedwater pump 5 through the bypass pipe 13 and bypass valve 14, and after being pressurized, it enters the economizer 7. After being heated, it enters the steam drum 8.

[0032] When the flue gas contains corrosive gases, to ensure that the outer wall temperature of the heated surface of the economizer 7 is above the flue gas dew point, it is necessary to increase the water temperature entering the economizer 7. At this time, the bypass valve 14 is closed, and the opening of the high-temperature water regulating valve 10 is opened and adjusted. The high-temperature feedwater entering the steam drum 8 from the economizer 7 is diverted into the high-temperature water pipe, passing sequentially through the high-temperature water flow meter 9 and the high-temperature water regulating valve 10 before entering the first-stage mixer 2 to mix with the low-pressure feedwater, thus increasing the feedwater temperature. The larger the opening of the high-temperature water regulating valve 10, the higher the water temperature after passing through the first-stage mixer 2. Since the return flow of high-temperature water will increase the load on the feedwater pump 5 and increase the flow resistance of the economizer 7, leading to a decrease in the outlet force of the economizer 7 and affecting the feedwater flow rate entering the steam drum 8, the high-temperature water return flow rate should not be too large, and should not exceed 1 / 2 of the rated steam flow rate. To limit the return flow of high-temperature water, the diameter of the selected high-temperature water pipe should be half that of the feed water pipe. A high-temperature water flow meter 9 is installed to measure the flow rate. When the flow rate is too high, the opening of the high-temperature water regulating valve 10 is reduced to decrease the flow rate. When it is necessary to further increase the feed water temperature, the second-stage mixer 3 is activated. The second-stage mixer 3 is heated by steam. The steam enters the second-stage mixer 3 through the steam regulating valve 12 and mixes with the water from the first-stage mixer 2 to further increase the feed water temperature. The mixture then enters the feed water pump 5 through the pre-pump 4, and finally passes through the economizer 7 into the steam drum 8.

[0033] During use, the calculated or experimentally obtained dew point temperature and the flow limit are input via the input panel. When the temperature measuring mechanism 6 is lower than the input dew point temperature, the processor, through the actuator, closes the bypass valve 14, starts the pre-pump 4, and gradually opens the high-temperature water regulating valve 10. When the temperature measuring mechanism 6 and the input dew point temperature are within the set error (e.g., set deviation ±5℃), the operation of the high-temperature water regulating valve 10 stops, maintaining stability. If it is still lower than the input dew point temperature, the opening of the high-temperature water regulating valve 10 continues to increase. If the maximum allowable flow rate is reached and the temperature measuring mechanism 6 is still lower than the input dew point temperature, the steam regulating valve 12 is opened. The steam regulating valve 12 is adjusted until the temperature measuring mechanism 6 and the input dew point temperature are within the set error (e.g., set deviation ±5℃), then the adjustment is paused. The adjustment continues as needed to maintain this state, depending on the operating conditions.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0035] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A device for regulating the wall temperature of a boiler back-heat surface, comprising a low-pressure feed water tube, characterized in that: The low-pressure feed water pipe is sequentially provided with a first water mixer, a second water mixer, a feed water pump and a coal economizer; and the coal economizer is connected with a steam drum; A bypass pipe is connected between the first water mixer, the second water mixer and the feed water pump; A high-temperature water pipe is connected to the coal economizer-steam drum pipe through a tee joint, and the high-temperature water pipe is connected with the first water mixer; and the high-temperature water pipe is sequentially provided with a high-temperature water flow meter and a high-temperature water regulating valve; The second water mixer is connected with external steam through a steam pipe, and the steam pipe is provided with a steam regulating valve; A temperature measuring mechanism is arranged between the feed water pump and the coal economizer.

2. A device for regulating wall temperature of a boiler back surface heating surface according to claim 1, characterized in that, A pre-pump is arranged between the second water mixer and the feed water pump.

3. A device for regulating wall temperature of a boiler back surface heating surface according to claim 1, characterized in that, The diameter of the high-temperature water pipe is 1 / 2 of the diameter of the low-pressure feed water pipe.

4. A device for regulating wall temperature of a boiler back surface heating surface according to claim 1, characterized in that, The boiler tail heating surface wall temperature regulating device is controlled by a processor; The temperature measuring mechanism and the flow meter are respectively connected with the processor through transmitters; the processor is connected with an execution unit, and the execution unit is connected with a steam regulating valve, a bypass valve and a high-temperature water regulating valve; The processor is also connected with an input panel.

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