Dioxin-controllable hazardous waste waste heat boiler system and control method thereof

Abstract

The present invention provides a hazardous waste waste heat boiler system and control method with controllable dioxin. The hazardous waste waste heat boiler system includes a waste heat boiler, a steam drum, a heat exchanger, a first regulating valve group, a feed water pump group and a deaerator, and a second regulating valve group and a circulation pipeline connected in sequence; the waste heat boiler includes a flue gas inlet and a flue gas outlet; the heat exchanger is arranged in the waste heat boiler and is located at one end of the flue gas outlet; the deaerator removes oxygen from the supply water to supply the feed water pump group; the feed water pump group supplies water to the heat exchanger and the steam drum respectively; the first regulating valve group is arranged on the pipeline from the feed water pump group to the heat exchanger; the second regulating valve group is arranged on the pipeline from the feed water pump group to the steam drum; the steam drum receives water heated by heat exchange in the heat exchanger and water from the feed water pump group respectively, and the water in the steam drum is heated by heat exchange to form water vapor and circulate to the steam drum; the circulation pipeline is arranged from the water outlet of the heat exchanger to the water inlet of the deaerator. The control method controls the dioxin content in the outlet flue gas by controlling the flue gas temperature at the outlet of the boiler.

Description

Technical Field

[0001] The present invention belongs to the field of hazardous waste treatment, and in particular to a hazardous waste waste heat boiler system and a control method thereof, in which dioxins can be controlled when treating flue gas generated by burning solid hazardous waste. Background Art

[0002] In the hazardous waste industry, the flue gas generated by the combustion of solid hazardous waste needs to enter the waste heat boiler for cooling before entering the quench tower. Solid hazardous waste refers to solid waste that is listed in the national hazardous waste list or identified according to the national hazardous waste identification standards and identification methods as having one or more hazardous characteristics such as corrosiveness, toxicity, flammability, reactivity and infectivity, as well as solid waste that does not exclude the above hazardous characteristics. For example: HW11 distillation residue (acid tar and other tars produced in the process of petroleum refining), HW13 organic resin waste (unqualified products produced in the production process of resin, latex, plasticizer, glue / adhesive), etc. At present, the waste heat boilers in the hazardous waste industry do not have temperature control devices. They are all designed according to the air volume and most of the margin is reserved. They cannot heat the feed water or control the flue gas temperature at the outlet of the waste heat boiler and the inlet of the quench tower. The hazardous waste industry requires that the boiler outlet (quench tower inlet) temperature fluctuate between 500-550℃, and rapidly drop to below 200℃ after reaching the quench tower to prevent dioxins from resynthesizing at low temperatures between 250-500℃. During the operation of the waste heat boiler, the dust (i.e., fly ash) in the flue gas of the hazardous waste industry is easily accumulated on the heat exchange surface, causing the boiler outlet temperature to increase, which is difficult to control within the range of 500-550℃. The outlet temperature can only be reduced by adding an ash accumulation vibration device to clean the ash accumulation; if the outlet temperature is low, the boiler heat exchange surface can only be reduced to increase the boiler outlet temperature; or the temperature after ash accumulation can be reserved and the flue gas temperature can be controlled by increasing the number of quench tower spray guns and water spraying volume with sufficient adjustment margin, resulting in a waste of waste heat energy; when the temperature is uncontrollable and the vibration has no effect, the boiler can only be stopped for cleaning, which seriously affects the treatment progress. Summary of the invention

[0003] The first object of the present invention is to provide a hazardous waste waste heat boiler system with controllable dioxins. The hazardous waste waste heat boiler system has a temperature control device and can achieve full-process temperature control to control the boiler outlet flue gas temperature, thereby controlling the dioxin content in the outlet flue gas.

[0004] The second object of the present invention is to provide a method for controlling the dioxin content in the outlet flue gas of the hazardous waste heat boiler system as described above, which can achieve full-process temperature regulation, control the boiler outlet flue gas temperature, and thus control the dioxin content in the outlet flue gas.

[0005] To achieve the first purpose, the present invention adopts the following technical solutions:

[0006] A dioxin-controllable hazardous waste waste heat boiler system comprises a waste heat boiler, a steam drum, a heat exchanger, a first regulating valve group, a feedwater pump group and a deaerator, and a second regulating valve group and a circulation pipeline, which are sequentially connected through pipelines;

[0007] The waste heat boiler comprises a flue gas inlet and a flue gas outlet for the inlet and outlet of flue gas generated by the combustion of solid hazardous waste;

[0008] The heat exchanger is arranged in the waste heat boiler and located at one end of the flue gas outlet, and is used to perform heat exchange and cooling on the flue gas after entering the waste heat boiler through the flue gas inlet and cooling the flue gas;

[0009] The deaerator is used to remove oxygen from the supply water to supply the water supply pump group;

[0010] The water feed pump group is used to supply water to the heat exchanger and the steam drum respectively;

[0011] The first regulating valve group is arranged on the pipeline from the water supply pump group to the heat exchanger, and is used to regulate the water inlet flow rate of the water supply pump group into the heat exchanger;

[0012] The second regulating valve group is arranged on the pipeline from the feed water pump group to the steam drum, and is used to adjust the water inlet flow rate of the feed water pump group into the steam drum;

[0013] The drum is used to receive the water heated by the heat exchanger and the water from the water supply pump group, and the water in the drum is heated by the flue gas entering the waste heat boiler through the flue gas inlet to form water vapor and circulate in the drum.

[0014] The circulation pipeline is arranged from the water outlet of the heat exchanger to the water inlet of the deaerator, and is used to circulate the water heated by the heat exchanger to the deaerator when starting / stopping the furnace.

[0015] Preferably, a third regulating valve group is further provided on the circulation pipeline for regulating the water flow from the heat exchanger to the deaerator.

[0016] Preferably, at least one temperature measuring device is also provided on the water outlet pipeline of the heat exchanger, for detecting the outlet water temperature of the heat exchanger to prevent the heat exchange tubes in the heat exchanger from overheating.

[0017] Preferably, there are two temperature measuring devices, which are arranged on the water outlet pipeline of the heat exchanger at a distance of 1-5m.

[0018] Preferably, the temperature measuring device is a resistance thermometer.

[0019] Preferably, the heat exchanger is also equipped with a dust cleaning device.

[0020] To achieve the second purpose, the present invention adopts the following technical solutions:

[0021] A method for controlling the dioxin content in the outlet flue gas using the hazardous waste waste heat boiler system as described above, comprising: using the heat exchanger to perform heat exchange and cooling on the flue gas that has been cooled after entering the waste heat boiler through the flue gas inlet; using the water supply pump group to supply water to the heat exchanger, and using the first regulating valve group to adjust the water flow rate of the water supply pump group to the heat exchanger, so as to control the flue gas temperature output through the flue gas outlet to 500-550°C.

[0022] Preferably, when the temperature of the flue gas output through the flue gas outlet is less than 500° C., the first regulating valve group is used to reduce the water inlet flow rate of the heat exchanger.

[0023] Preferably, when the temperature of the flue gas output through the flue gas outlet is greater than 550° C., the first regulating valve group is used to increase the water inlet flow rate of the heat exchanger.

[0024] Preferably, when starting / shutting down the furnace, the water heated by heat exchange in the heat exchanger is circulated to the deaerator via the circulation pipeline; and the water flow rate from the heat exchanger to the deaerator is adjusted via the third regulating valve group.

[0025] Preferably, the second regulating valve group is used to adjust the water flow rate of the water feed pump group into the steam drum to maintain a stable liquid level in the steam drum.

[0026] The beneficial effects of the present invention are:

[0027] (1) The hazardous waste waste heat boiler system of the present invention is provided with a heat exchanger at one end of the flue gas outlet in the waste heat boiler, and a first regulating valve group is provided on the pipeline from the water supply pump group to the heat exchanger, so as to achieve heat exchange and cooling of the flue gas after cooling down entering the waste heat boiler through the flue gas inlet; the water inlet flow of the heat exchanger is regulated by the first regulating valve group, so as to achieve full process regulation of the flue gas temperature at the boiler outlet, so as to control it within the range of 500-550°C, so as to prevent the low-temperature resynthesis of dioxins, control the content of dioxins in the outlet flue gas, and reduce waste heat waste;

[0028] (2) The hazardous waste waste heat boiler system of the present invention circulates the water heated by heat exchange in the heat exchanger to the deaerator when the furnace is started / shutdown through a circulation pipeline arranged from the water outlet of the heat exchanger to the water inlet of the deaerator, so that the deaerator can transport the water to the heat exchanger through the water feed pump group to realize water circulation and prevent the heat exchanger from burning dry; at the same time, the water in the deaerator can be heated during the furnace start-up stage; through the arrangement of the water outlet of the heat exchanger to the water inlet of the steam drum, the water heated by heat exchange in the heat exchanger can be used as the steam drum inlet water, thereby ensuring the water feed temperature of the steam drum;

[0029] (3) The hazardous waste waste heat boiler system of the present invention can detect the outlet water temperature of the heat exchanger by installing at least one temperature measuring device on the outlet water pipeline of the heat exchanger, thereby preventing the heat exchange tubes in the heat exchanger from being damaged due to overheating;

[0030] (4) The control method of the present invention is simple and easy to operate, and can realize the whole process temperature regulation, control the flue gas temperature at the boiler outlet, thereby controlling the dioxin content in the flue gas at the outlet, and can ensure the feed water temperature of the steam drum. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a dioxin-controllable hazardous waste waste heat boiler system according to an embodiment of the present invention;

[0032] Figure 2 It is a structural schematic diagram of an existing hazardous waste waste heat boiler system. DETAILED DESCRIPTION

[0033] The technical scheme and its effects of the present invention are further described below through specific implementation methods. The following implementation methods are only used to illustrate the content of the present invention, and the invention is not limited to the following implementation methods or examples. Simple changes made to the present invention using the concept of the present invention are all within the scope of protection claimed by the present invention.

[0034] like Figure 1 As shown, the dioxin-controllable hazardous waste waste heat boiler system of the present invention comprises a waste heat boiler 1, a steam drum 2, a heat exchanger 3, a first regulating valve group 4, a feed water pump group 5 and a deaerator 8, as well as a second regulating valve group 9 and a circulation pipeline 10, which are sequentially connected through pipelines;

[0035] The waste heat boiler 1 comprises a flue gas inlet 6 and a flue gas outlet 7 for the flue gas generated by the combustion of solid hazardous waste;

[0036] The heat exchanger 3 is arranged in the waste heat boiler 1 and located at one end of the flue gas outlet 7, and is used to perform heat exchange and cooling on the flue gas that has been cooled and entered into the waste heat boiler 1 through the flue gas inlet 6;

[0037] The deaerator 8 is used to remove oxygen from the water supply to supply the water supply pump group 5;

[0038] The water feed pump group 5 is used to supply water to the heat exchanger 3 and the steam drum 2 respectively;

[0039] The first regulating valve group 4 is arranged on the pipeline from the water supply pump group 5 to the heat exchanger 3, and is used to adjust the water inlet flow rate of the water supply pump group 5 into the heat exchanger 3;

[0040] The second regulating valve group 9 is arranged on the pipeline from the water supply pump group 5 to the steam drum 2, and is used to adjust the water inlet flow rate of the water supply pump group 5 into the steam drum 2;

[0041] The drum 2 is used to receive the water heated by the heat exchanger 3 and the water from the water supply pump group 5, and the water in the drum 2 and the flue gas entering the waste heat boiler 1 through the flue gas inlet 6 are heated by heat exchange to form water vapor and circulate to the drum 2;

[0042] The circulation pipeline 10 is arranged from the water outlet of the heat exchanger 3 to the water inlet of the deaerator 8, and is used to circulate the water heated by the heat exchanger 3 to the deaerator 8 when starting / stopping the furnace.

[0043] Those skilled in the art can understand that the first regulating valve group 4 and the second regulating valve group 9 are both regulating valve groups commonly used in the field, including an electric regulating valve and an inlet valve and an outlet valve located on the inlet pipeline and the outlet pipeline of the electric regulating valve, and a bypass valve located on the bypass pipeline, and the two ends of the bypass pipeline are respectively connected to the water inlet of the inlet valve and the water outlet of the outlet valve.

[0044] Those skilled in the art will appreciate that the water supply to the deaerator is deionized water, also called reverse osmosis water, which can avoid scaling of the subsequent waste heat boiler after oxygen is removed by the deaerator.

[0045] Those skilled in the art can understand that the waste heat boiler is provided with a water-cooled wall, a downcomer, a liquid manifold, an ascending pipe and a steam manifold, and the downcomer, the liquid manifold, the water-cooled wall, the ascending pipe and the steam manifold are sequentially connected; the water in the drum 2 is collected to the liquid manifold at the bottom of the waste heat boiler 1 through the downcomer, and is connected to the water-cooled wall, and then the water in the water-cooled wall is heat-exchanged and heated with the flue gas entering the waste heat boiler 1 through the flue gas inlet 6 to form water vapor (steam), which rises from the ascending pipe and is collected to the steam manifold at the top of the waste heat boiler 1, and then the water vapor circulates to the drum 2; that is, the water and water vapor in the drum 2 are circulated through the downcomer, the liquid manifold, the water-cooled wall, the ascending pipe and the steam manifold which are sequentially connected; at the same time, the flue gas entering the waste heat boiler 1 through the flue gas inlet 6 is first heat-exchanged and cooled with the water in the water-cooled wall, and then is heat-exchanged and cooled in the heat exchanger 3 before being output from the flue gas outlet 7.

[0046] Those skilled in the art understand that when flue gas containing dioxins is cooled from high temperature to low temperature, it is easy to resynthesize in the range of 250-500°C.

[0047] The dioxin-controllable hazardous waste waste heat boiler system of the present invention is provided with a heat exchanger 3 at one end of the flue gas outlet 7 in the waste heat boiler 1, and a first regulating valve group 4 is provided on the pipeline from the water supply pump group 5 to the heat exchanger 3, so as to realize heat exchange and cooling of the flue gas after cooling down entering the waste heat boiler 1 through the flue gas inlet 6; the water inlet flow of the heat exchanger 3 is regulated by the first regulating valve group 4, so as to realize the whole process regulation of the flue gas temperature at the boiler outlet, so that it is controlled within the range of 500-550°C, so as to prevent the low-temperature regeneration of dioxins. Synthesis, control the content of dioxins in the outlet flue gas; and can avoid the increase of boiler outlet temperature due to the accumulation of dust (i.e. fly ash) in the flue gas of the hazardous waste industry on the heat exchange surface during the operation of the waste heat boiler 1, so there is no need to add an ash accumulation and beating device; it can also avoid the situation where the outlet temperature is too low and the boiler heat exchange surface needs to be reduced to increase the boiler outlet temperature; at the same time, there is no need to increase the number of quenching tower spray guns and the amount of water sprayed to control the flue gas temperature, thereby avoiding the waste of waste heat energy; it can also avoid the situation where the temperature is uncontrollable and the beating has no effect and the furnace can only be stopped for cleaning, affecting the production progress.

[0048] The dioxin-controllable hazardous waste waste heat boiler system of the present invention circulates the water heated by heat exchange in the heat exchanger 3 to the deaerator 8 through the circulation pipeline 10 arranged from the water outlet of the heat exchanger 3 to the water inlet of the deaerator 8 when the furnace is started / shutdown, so that the deaerator 8 can transport the water to the heat exchanger 3 through the feed water pump group 5 to realize water circulation, thereby preventing the heat exchanger 3 from drying out; at the same time, the water in the deaerator 8 can be heated during the furnace startup stage; through the arrangement from the water outlet of the heat exchanger 3 to the water inlet of the drum 2, the water heated by heat exchange in the heat exchanger 3 can be used as the inlet water of the drum 2, thereby ensuring the feed water temperature of the drum 2, so that the feed water temperature can be equal to or close to the saturation temperature under the pressure in the drum 2, thereby reducing the thermal stress caused by the temperature difference and improving the working condition of the drum 2.

[0049] In one embodiment, the heat exchanger 3 is also equipped with a dust cleaning device, such as an air shock wave soot blower, an acetylene soot blower, etc., to remove the dust accumulated on the heat exchange tubes in the heat exchanger 3, thereby preventing the heat exchanger 3 from being blocked by dust and causing the system to shut down.

[0050] In one embodiment, a third regulating valve group 11 is further provided on the circulation pipeline 10 for regulating the water flow rate from the heat exchanger 3 to the deaerator 8 .

[0051] In one embodiment, at least one temperature measuring device 12 is also provided on the outlet pipe of the heat exchanger 3, such as 2, 3, 4, 5, 6, etc., for detecting the outlet water temperature of the heat exchanger 3 to prevent the heat exchange tubes in the heat exchanger 3 from being damaged due to overheating. Preferably, there are two temperature measuring devices 12, and they are arranged on the outlet pipe of the heat exchanger 3 at intervals of 1-5m, so that when one of them breaks down, the other can be used for detection, ensuring that the detection is not interrupted as much as possible; and when there are only two temperature measuring devices 12, the interval between the two is relatively short, the detected temperature values ​​are relatively close, and the detection error is small; and compared with setting more temperature measuring devices 12, when there are only two temperature measuring devices 12, on the one hand, it is more convenient to install, and on the other hand, it is more resource-saving.

[0052] Those skilled in the art will appreciate that the temperature measuring device 12 may be a commonly used temperature measuring device in the art, such as a thermal resistance thermometer, a thermistor thermometer, and a thermocouple thermometer. In one embodiment, the temperature measuring device 12 is a thermal resistance thermometer. Thermal resistance thermometers are easy to obtain and have low installation costs.

[0053] The present invention also provides a method for controlling the dioxin content in the outlet flue gas using the hazardous waste waste heat boiler system as described above, comprising: using the heat exchanger 3 to perform heat exchange and cooling on the flue gas after cooling after entering the waste heat boiler 1 through the flue gas inlet 6; using the water supply pump group 5 to supply water to the heat exchanger 3, and using the first regulating valve group 4 to adjust the water inlet flow rate of the water supply pump group 5 to the heat exchanger 3, so as to control the flue gas temperature output through the flue gas outlet 7 to 500-550°C, thereby preventing the low-temperature resynthesis of dioxins on the one hand, thereby controlling the dioxin content in the outlet flue gas, and preventing waste heat waste on the other hand.

[0054] During the entire control process, the first regulating valve group 4, the outlet temperature of the heat exchanger 3, the second regulating valve group 9 and the liquid level of the drum 2 form a linkage regulation: the second regulating valve group 9 maintains the feed water flow of the drum 2, supplies water to the drum 2, and adjusts the feed water amount according to the liquid level of the drum 2; the first regulating valve group 4 tracks the outlet temperature of the waste heat boiler 1, and adjusts the feed water amount according to the outlet temperature of the waste heat boiler 1; at the same time, the feed water to the heat exchanger 3 cannot be interrupted. For example, when the start-up / shutdown feed water amount is small, the first regulating valve group 4 is prioritized for water supply; and a water supply circulation pipeline 10 is set. If no water supply is needed when starting the boiler, it is also necessary to ensure that there is water in the heat exchanger 3, and the circulation pipeline 10 is opened to ensure the safe operation of the heat exchanger 3.

[0055] Those skilled in the art understand that dioxins are easily resynthesized at low temperatures. Therefore, when the flue gas outlet temperature is lower than 500°C, the dioxin content in the outlet flue gas is relatively high. When the flue gas outlet temperature is higher than 550°C, although the dioxin content in the outlet flue gas is relatively low, when it enters the quenching tower, it is necessary to increase the number of quenching tower spray guns and the amount of water sprayed to control the flue gas temperature, which will cause waste heat. When the flue gas outlet temperature is 500-550°C, the low-temperature resynthesis of dioxins can be prevented, ensuring that the dioxin content in the outlet flue gas is relatively low, and the waste of waste heat can be reduced.

[0056] In one embodiment, when the temperature of the flue gas output through the flue gas outlet 7 is less than 500° C., the first regulating valve group 4 is used to reduce the water inlet flow rate of the heat exchanger 3 .

[0057] In one embodiment, when the temperature of the flue gas output through the flue gas outlet 7 is greater than 550° C., the first regulating valve group 4 is used to increase the water inlet flow rate of the heat exchanger 3 .

[0058] In one embodiment, when starting / shutting down the furnace, the circulation pipeline 10 is used to circulate the water heated by heat exchange in the heat exchanger 3 to the deaerator 8, so that the deaerator 8 can transport the water to the heat exchanger 3 through the water supply pump group 5, thereby realizing the circulation of water and preventing the heat exchanger 3 from drying out; at the same time, the water in the deaerator 8 can be heated during the furnace startup stage; and the third regulating valve group 11 is used to adjust the water flow rate from the heat exchanger 3 to the deaerator 8.

[0059] In one embodiment, the second regulating valve group 9 is used to adjust the water flow rate of the water feed pump group 5 into the steam drum 2 to maintain a stable liquid level in the steam drum 2.

[0060] The present invention Figure 1 The operation process of the dioxin-controllable hazardous waste waste heat boiler system of the illustrated embodiment is as follows:

[0061] The oxygen in the water supply is removed by the deaerator 8, and the water output is divided into two parts through the water supply pump group 5;

[0062] A portion of the water is output to the water heater 3, and heat exchange and cooling are performed on the flue gas after the flue gas enters the waste heat boiler 1 through the flue gas inlet 6 and is cooled. According to the flue gas temperature output from the flue gas outlet 7, the first regulating valve group 4 is used to adjust the water inlet flow rate of the water supply pump group 5 into the heat exchanger 3, so as to control the flue gas temperature output from the flue gas outlet 7 to be 500-550°C; when the flue gas temperature output from the flue gas outlet 7 is less than 500°C, the first regulating valve group 4 is adjusted to reduce the water inlet flow rate of the heat exchanger 3; when the flue gas temperature output from the flue gas outlet 7 is greater than 550°C, the first regulating valve group 4 is adjusted to increase the water inlet flow rate of the heat exchanger 3. The water inlet flow of the heat exchanger 3 is controlled; when the furnace is started / shut down, the water heated by the heat exchanger 3 is circulated to the deaerator 8 by the circulation pipeline 10, and the water flow from the heat exchanger 3 to the deaerator 8 is adjusted by the third regulating valve group 11, so that the deaerator 8 can transport the water to the heat exchanger 3 through the water feed pump group 5 to realize the circulation of water; during this period, the outlet water temperature of the heat exchanger 3 is measured by the temperature measuring device 12. If the measured outlet water temperature is close to or reaches the heat resistance temperature of the heat exchange tube, the first regulating valve group 4 is used to appropriately reduce the inlet water flow of the heat exchanger 3 to prevent the heat exchange tube from being damaged due to overheating;

[0063] The other part is output to the steam drum 2, and the second regulating valve group 9 is used to adjust the water flow rate of the water feed pump group 5 into the steam drum 2, and the water heated by heat exchanger 3 is supplied to the steam drum 2, so as to ensure the feed water temperature of the steam drum 2 and maintain the liquid level in the steam drum 2 stable.

[0064] The dioxin-controllable hazardous waste waste heat boiler system and control method thereof of the present invention can heat the feed water of the steam drum and can control the flue gas temperature at the outlet of the waste heat boiler and the inlet of the quenching tower to keep it within the range of 500-550°C, which meets the requirements of the hazardous waste industry for the flue gas temperature at the boiler outlet (quenching tower inlet), can prevent the low-temperature resynthesis of dioxins, thereby making the dioxin content in the outlet flue gas controllable, and can reduce the waste heat waste, and can quickly reduce the flue gas to below 200°C after reaching the quenching tower to prevent the low-temperature resynthesis of dioxins between 250-500°C.

[0065] The “export flue gas” in the present invention refers to the outlet flue gas of the boiler in the hazardous waste heat boiler system, that is, the flue gas output through the flue gas outlet 7 .

[0066] Example 1

[0067] Using the Invention Figure 1 The dioxin-controllable hazardous waste waste heat boiler system shown in the figure treats the flue gas produced by the incineration of solid hazardous waste with an incineration capacity of 50t / d according to its aforementioned operation process; wherein the water supply flow range of the heat exchanger 3 is 0.3-2t / h, and the design flue gas feed rate of the waste heat boiler 1 is 14000-16000Nm 3 / h;

[0068] During the process of starting up and heating up the furnace, the heat exchanger 3 circulates water to the deaerator 8 through the circulation pipeline 10, and the third regulating valve group 11 is used to adjust the water flow from the heat exchanger 3 to the deaerator 8, so that the water in the deaerator 8 is heated to the saturation temperature under the operating pressure of the deaerator 8, and the deaerator 8 is used to remove the undissolved oxygen or other non-condensable gases in the condensed water to achieve the outlet water quality required by the deaerator 8; when the flue gas feed rate of the waste heat boiler 1 is less than 14000Nm 3 / h, the heat exchange area in the waste heat boiler 1 has less ash and high heat exchange efficiency. The flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 is 400-500°C. At this time, the water inlet flow rate of the water feed pump group 5 into the heat exchanger 3 is reduced by adjusting the first regulating valve group 4, thereby reducing the heat exchange rate of the heat exchanger 3, and then increasing the flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 to 500-550°C;

[0069] As the operation time increases, the flue gas feed rate of waste heat boiler 1 reaches 15000Nm 3 / h, the heat exchange surface dust in the waste heat boiler 1 increases, and dust still accumulates on the heat exchange surface after vibration, the heat exchange efficiency is reduced, and the flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 is greater than 550°C. At this time, the water inlet flow rate of the water feed pump group 5 into the heat exchanger 3 is increased by adjusting the first regulating valve group 4, thereby improving the heat exchange rate of the heat exchanger 3, and then reducing the flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 to 500-550°C, and at the same time increasing the steam production. The produced steam is transported from the heat exchanger 3 to the drum 2, and is output from the drum 2 for use;

[0070] In the above process, the temperature measuring device 12 - a resistance thermometer is used to detect the outlet water temperature of the heat exchanger 3 to prevent the heat exchange tubes in the heat exchanger 3 from overheating; at the same time, the opening of the second regulating valve group 9 is adjusted according to the liquid level of the steam drum 2, thereby adjusting the water inlet flow rate of the water feed pump group 5 into the steam drum 2 to maintain the liquid level in the steam drum 2 stable.

[0071] It can be seen that Example 1 can stably control the flue gas outlet temperature at 500-550°C, which meets the temperature requirements of the hazardous waste industry; the dioxin content in the outlet flue gas is detected to be lower than 0.21TEQ ng / m 3 , in line with the provisions of the hazardous waste incineration pollution control standard (GB18484-2001) on the dioxin content in the outlet flue gas, that is, less than 0.5TEQ ng / m 3 .

[0072] Comparative Example 1

[0073] use Figure 2 The hazardous waste waste heat boiler system shown in the figure treats the flue gas produced by the incineration of solid hazardous waste with an incineration capacity of 50t / d; the designed flue gas feed rate of the waste heat boiler 1 is 14000-16000Nm 3 / h;

[0074] During the process of starting the furnace and heating up, steam is not yet generated in the drum 2. Steam will be generated only after it has been running for a period of time. Then, the steam in the drum 2 is transported to the deaerator 8, and the third regulating valve group 11 is used to adjust the steam flow from the drum 2 to the deaerator 8, and the water in the deaerator 8 is heated to the saturation temperature under the operating pressure of the deaerator 8. The deaerator 8 is used to remove the undissolved oxygen or other non-condensable gases in the condensed water to achieve the outlet water quality required by the deaerator 8. When the flue gas feed rate of the waste heat boiler 1 is less than 14000Nm 3 / At 1500 ℃, the heat exchange area in the waste heat boiler 1 is less ash-covered, the heat exchange efficiency is high, and the flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 is 400-500℃; at this time, the dioxin content in the outlet flue gas is detected to be about 0.35TEQ ng / m 3 ;

[0075] As the operation time increases, the flue gas feed rate of waste heat boiler 1 reaches 15000Nm 3 / h, the heat exchange surface in the waste heat boiler 1 is covered with dust, and the heat exchange surface is still covered with dust after vibration, which reduces the heat exchange efficiency. The flue gas temperature output from the flue gas outlet 7 of the waste heat boiler 1 is greater than 550℃, and can only enter the quenching tower for water spraying to cool down. At this time, the dioxin content in the outlet flue gas is detected to be about 0.21TEQ ng / m 3 ;

[0076] In the above process, the opening of the second regulating valve group 9 is adjusted according to the liquid level of the steam drum 2, thereby adjusting the water inlet flow rate of the water feed pump group 5 into the steam drum 2 to maintain the liquid level in the steam drum 2 stable.

[0077] It can be seen that in the waste heat boiler system of comparative example 1, in order to ensure the liquid level of the drum 2, it is impossible to control the flue gas outlet temperature by adjusting the water supply of the waste heat boiler 1, thereby causing the flue gas outlet temperature of the waste heat boiler 1 to be unadjustable, and further causing the flue gas outlet temperature to be low and the dioxin content in the outlet flue gas to be high in the initial stage of system operation; and as the operating time increases, the heat exchange area in the waste heat boiler 1 increases in dust, the heat exchange efficiency decreases, and thus the flue gas outlet temperature will also increase accordingly. Although the dioxin content in the outlet flue gas is reduced, it is necessary to increase the number of quenching tower spray guns and the amount of water sprayed to control the flue gas temperature when it enters the quenching tower, which will cause waste heat waste.

[0078] According to the comparison between Example 1 and Comparative Example 1, it can be seen that:

[0079] 1. In Example 1, when the furnace is started and heated, hot water begins to be generated in the heat exchanger 3 and is supplied to the deaerator 8 for heating; while in Comparative Example 1, steam is generated in the drum 2 after a period of operation and is supplied to the deaerator 8 for heating; therefore, compared with Comparative Example 1, the heating time for heating the water in the deaerator 8 to the saturation temperature under the operating pressure of the deaerator 8 in Example 1 is significantly shortened, so that the insoluble oxygen or other incondensable gases in the condensate can be removed more quickly, so as to avoid or reduce the influence of the insoluble oxygen or other incondensable gases in the condensate on the waste heat boiler 1;

[0080] 2. Compared with Comparative Example 1, the waste heat boiler system of Example 1 can adjust the water inlet flow of the heat exchanger 3 in real time according to the change trend of the flue gas outlet temperature, thereby adjusting the flue gas outlet temperature in real time to keep it at 500-550°C, which can prevent the low flue gas outlet temperature from causing low-temperature regeneration of dioxins in the initial stage of system operation, thereby causing high dioxin content therein, and can also prevent the high flue gas outlet temperature from causing waste heat waste when the system is running for a long time or overloaded (that is, it can improve the flue gas outlet temperature in the initial stage of system operation). The flue gas outlet temperature can be reduced to 500-550°C to reduce the dioxin content therein, and the flue gas outlet temperature can be reduced to 500-550°C after the system has been running for a period of time to avoid waste heat); and when the water inlet flow of the heat exchanger 3 is increased to reduce the flue gas outlet temperature, the steam production will be increased at the same time (the steam production increase reaches 1-1.5t / h), and the produced steam is transported from the heat exchanger 3 to the steam drum 2, and then output from the steam drum 2 for use, such as for heating in the north in winter and for enterprises producing steam or power generation, thereby reducing waste heat waste;

[0081] The flue gas outlet temperature is maintained at 500-550°C, which can reduce the water spraying amount and usage load in the quenching tower, and can avoid the following situation: when the flue gas outlet temperature is too high, the spray gun in the quenching tower is not enough to reduce it to below 200°C when entering the quenching tower for cooling, so that the incineration treatment amount of solid hazardous waste can only be reduced, that is, the flue gas treatment amount is reduced, or the furnace is stopped to clean the ash accumulation in the waste heat boiler 1, resulting in production reduction and shutdown;

[0082] 3. Compared with Comparative Example 1, the waste heat boiler system of Example 1 can use the water heated by heat exchange in the heat exchanger 3 as the inlet water of the steam drum 2, thereby ensuring the feed water temperature of the steam drum 2.

Claims

1. A dioxin-controllable hazardous waste waste heat boiler system, characterized in that: It comprises a waste heat boiler (1), a steam drum (2), a heat exchanger (3), a first regulating valve group (4), a feed water pump group (5) and a deaerator (8), which are sequentially connected through pipelines, as well as a second regulating valve group (9) and a circulation pipeline (10); The waste heat boiler (1) comprises a flue gas inlet (6) and a flue gas outlet (7) for the inlet and outlet of flue gas generated by the combustion of solid hazardous waste; The heat exchanger (3) is arranged in the waste heat boiler (1) and is located at one end of the flue gas outlet (7), and is used to perform heat exchange and cooling on the flue gas after it enters the waste heat boiler (1) through the flue gas inlet (6) and is cooled; the heat exchanger (3) is also equipped with a soot cleaning device, and the soot cleaning device includes an acetylene soot blower; The deaerator (8) is used to remove oxygen from the supply water to supply the water supply pump group (5); The water feed pump group (5) is used to respectively supply water to the heat exchanger (3) and the steam drum (2); The first regulating valve group (4) is arranged on the pipeline from the water supply pump group (5) to the heat exchanger (3), and is used to regulate the water inlet flow rate of the water supply pump group (5) into the heat exchanger (3); The second regulating valve group (9) is arranged on the pipeline from the water supply pump group (5) to the steam drum (2) and is used to adjust the water inlet flow rate of the water supply pump group (5) into the steam drum (2); The drum (2) is used to receive water heated by heat exchange in the heat exchanger (3) and water from the water supply pump group (5), and the water in the drum (2) and the flue gas entering the waste heat boiler (1) through the flue gas inlet (6) are heated by heat exchange to form water vapor, which is circulated into the drum (2); The circulation pipeline (10) is arranged from the water outlet of the heat exchanger (3) to the water inlet of the deaerator (8), and is used to circulate the water heated by heat exchange in the heat exchanger (3) into the deaerator (8) when the furnace is started / shut down.

2. The hazardous waste waste heat boiler system according to claim 1, characterized in that: The circulation pipeline (10) is also provided with a third regulating valve group (11) for regulating the water flow rate from the heat exchanger (3) to the deaerator (8).

3. The hazardous waste waste heat boiler system according to claim 1 or 2, characterized in that: At least one temperature measuring device (12) is also provided on the water outlet pipeline of the heat exchanger (3) for detecting the water outlet temperature of the heat exchanger (3) to prevent the heat exchange tubes in the heat exchanger (3) from overheating.

4. The hazardous waste waste heat boiler system according to claim 3, characterized in that: There are two temperature measuring devices (12), which are arranged on the water outlet pipeline of the heat exchanger (3) at intervals of 1-5 m.

5. The hazardous waste waste heat boiler system according to claim 3, characterized in that: The temperature measuring device (12) is a thermal resistance thermometer.

6. A method for controlling the dioxin content in outlet flue gas using the hazardous waste heat boiler system as claimed in any one of claims 1 to 5, characterized in that: The control method comprises: using the heat exchanger (3) to perform heat exchange and cooling on the flue gas after it has been cooled and entered into the waste heat boiler (1) through the flue gas inlet (6); using the water supply pump group (5) to supply water into the heat exchanger (3), and using the first regulating valve group (4) to adjust the water flow rate of the water supply pump group (5) supplying water into the heat exchanger (3), so as to control the flue gas temperature output through the flue gas outlet (7) to be 500-550°C.

7. The control method according to claim 6, characterized in that: When the temperature of the flue gas output through the flue gas outlet (7) is less than 500° C., the first regulating valve group (4) is used to reduce the water inlet flow rate of the heat exchanger (3).

8. The control method according to claim 6, characterized in that: When the temperature of the flue gas output through the flue gas outlet (7) is greater than 550° C., the first regulating valve group (4) is used to increase the water inlet flow rate of the heat exchanger (3).

9. The control method according to claim 7 or 8, characterized in that: The circulation pipeline (10) is also provided with a third regulating valve group (11); when the furnace is started / shut down, the circulation pipeline (10) is used to circulate the water heated by the heat exchanger (3) into the deaerator (8); and the third regulating valve group (11) is used to regulate the water flow from the heat exchanger (3) to the deaerator (8).

10. The control method according to claim 9, characterized in that: The second regulating valve group (9) is used to regulate the water flow rate of the water supply pump group (5) into the steam drum (2) so as to maintain a stable liquid level in the steam drum (2).

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