A method for improving the co-firing situation of waste liquid in a thermal power plant

Abstract

The present invention discloses a method for improving the co-firing of waste liquid in a thermal power plant. The main problems of the original combustion system are mainly reflected in three aspects: the viscosity is too high due to insufficient heating of the waste liquid, the tar cannot be completely burned due to poor atomization of the spray gun, and high-temperature corrosion is caused by the alkali metal contained in the waste liquid. In view of the problems occurring in the previous combustion process, the main improvement measures include: reducing the viscosity of the waste liquid, controlling the waste liquid temperature within the range of 85°C to 95°C; strengthening combustion to ensure complete combustion of the waste liquid; and preventing high-temperature corrosion of the heating surface in the furnace. After the above improvements are completed, the situations such as coking, agglomeration, high-temperature corrosion, and serious lag in steam temperature regulation during the co-firing of waste liquid in the thermal power plant have been greatly improved.

Description

Technical Field

[0001] The present invention relates to a technical method for improving the production of BDO, and in particular to a method for improving the co-combustion of waste liquid in a thermal power plant. Background Art

[0002] The co-firing of waste liquid in thermal power plants is an important way for power plants to save costs, energy and the environment. However, most power plants will encounter many problems during the trial firing period, including damage to water pumps, accumulation of large amounts of solid matter in liquid storage tanks, blockage of tar pipelines, large-area coking in the furnace, agglomeration caused by electrostatic precipitators, high-temperature corrosion of heating surface tubes and serious lag in steam temperature regulation. These problems ultimately lead to the need to stop the co-firing operation, reducing the economic benefits of the thermal power plant. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a method for improving the co-combustion of waste liquid in thermal power plants, by conducting co-combustion tests, optimizing the combustion system, and improving the spray gun structure to achieve safe and efficient co-combustion of waste liquid and ensure upstream production.

[0004] The technical solution adopted by the present invention to solve the above-mentioned problem is: a method for improving the co-combustion of waste liquid in thermal power plants, which is characterized by the following:

[0005] 1. Conduct elemental analysis and ash characteristics analysis on the waste liquid generated by the thermal power plant; including elemental analysis (carbon, hydrogen, oxygen, nitrogen, sulfur, potassium, sodium) of the waste liquid, component content analysis of ash and moisture, ash characteristics analysis after complete combustion of the waste liquid (ash softening, deformation and melting temperature, etc.), physical characteristics analysis of the waste liquid (flash point, ignition point, freezing point and calorific value, etc.); use the data obtained to guide the physical structure design of the spray gun.

[0006] 2. Clean the condensate in the liquid storage tank; add internal heating equipment in the liquid storage tank, move the outlet of the liquid storage tank downward, and add a maintenance discharge port; temporarily connect the drain to the original drain pipe, reserve a spare outlet, and later discharge part or all of it directly into the liquid storage tank to recover the drain energy. You can also find an existing liquid storage tank or make a new tank.

[0007] 3. Add a waste liquid recycling system; design the waste liquid temperature to be higher than 90°C. Considering the influence of water evaporation, the waste liquid temperature of the entire process should be controlled within the range of 85°C to 95°C. At the same time, install multiple temperature and pressure measuring points in the liquid storage tank.

[0008] 4. The expansion of the waste liquid and steam pipelines is absorbed by elbows. All or part of the waste liquid pipeline is heated by a sleeve, and the heating pipe is made of stainless steel. Rearrange the pipeline for transporting waste liquid. The original steam heating pipeline is transformed to operate in parallel with the pipeline for transporting waste liquid, and a temperature measuring point is installed at the outlet of the steam heating pipeline. To prevent the accumulation of waste liquid in the pipeline from solidifying and blocking the pipeline, the pipeline and the system should be purged during the furnace shutdown period, and the steam purging of the pipeline should be increased.

[0009] 5. Add a steam pipeline for the steam atomizing spray gun, and install a temperature measuring point at the inlet of the spray gun; install pressure measuring points and regulating valves at both the pump outlet and the spray gun inlet, install a temperature measuring point at the pump outlet, and the waste liquid pipeline uses steam tracing heat; for the convenience of maintenance, the pipeline for transporting waste liquid uses flange connections.

[0010] 6. The spray gun needs to be redesigned. Temperature, pressure measuring points and regulating valves are installed on both the steam and waste liquid pipelines at the inlet of the spray gun; multiple spray guns are set, and they are introduced from the secondary air or primary air. The designed flow rate of the spray gun depends on the atomization experiment conditions.

[0011] 7. To ensure the complete combustion of the waste liquid and prevent high-temperature corrosion, it is necessary to determine the atomization method of the nozzle, as well as the flow parameters and structural parameters of the nozzle. Based on this, conduct waste liquid spray tests to provide technical support for the industrial operation of the waste liquid.

[0012] Compared with the prior art, the present invention has the following advantages and effects: By conducting co-firing tests, optimizing the combustion system, and improving the structure of the spray gun, the present invention realizes the safe and efficient co-firing of waste liquid, ensures upstream production, reduces the economic cost of the thermal power plant, saves resources, has extremely high economic benefits and environmental protection value, and provides an effective guarantee for the co-firing production of waste liquid in the thermal power plant. Brief Description of the Drawings

[0013] Figure 1 It is a schematic structural diagram of the combustion system before the transformation of the waste liquid co-firing in the thermal power plant.

[0014] Figure 2 It is a schematic structural diagram of the combustion system after the transformation of the waste liquid co-firing in the thermal power plant. Detailed Embodiments

[0015] The present invention will be further described in detail below in conjunction with the drawings and through embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0016] Embodiment

[0017] The waste liquid in the thermal power plant contains various substances and has a complex composition. It is difficult for general treatment methods to make the treated waste liquid meet the discharge standards. Co-firing the waste liquid in an air separation boiler is a better method at present. Therefore, it is urgent to conduct co-firing tests, optimize the combustion system, improve the structure of the spray gun, realize the safe and efficient co-firing of waste liquid, and ensure upstream production.

[0018] like Figure 1 As shown, the main problems of the original combustion system are that the waste liquid is not heated enough resulting in excessive viscosity, the spray gun has poor atomization resulting in the tar not being completely burned out, and the waste liquid contains alkali metals resulting in high temperature corrosion.

[0019] In response to the problems that occurred in the early combustion process, the main improvement measures include the following three parts:

[0020] First, reduce the viscosity of the waste liquid and control the temperature of the waste liquid within the range of 85℃ to 95℃. This includes improving the heating method of the liquid storage tank, using internal heating, arranging coil heating inside the liquid storage tank, and adding a waste liquid recirculation system; steam heating is used in the waste liquid transportation pipeline; and the spray gun is introduced from the burner area.

[0021] Secondly, strengthen combustion to ensure that the waste liquid is completely burned out. This includes designing a new spray gun to ensure the atomization effect; conducting atomization tests to determine the reasonable flow parameters, structural parameters and installation angle of the spray gun; and reasonably distributing air to strengthen combustion in the furnace.

[0022] Finally, prevent high temperature corrosion of the heating surface in the furnace. This includes introducing the spray gun from the burner area to reduce the content of alkali metals in the ash; designing the spray gun flow and structural flow according to the atomization experiment; and rationally utilizing the aerodynamic field in the furnace to prevent the jet from adhering to the wall. Based on the above solutions, the modified system diagram is designed, as shown below: Figure 2 shown.

[0023] In this embodiment, a thermal power plant waste liquid co-incineration is taken as an example. The plant is operating at a high efficiency beyond the design load, and the discharge of waste liquid as a byproduct of production is also increasing. The load of the waste liquid incinerator currently equipped is designed according to the original waste liquid discharge, and the plant is only equipped with one incinerator. The plant's operating department produces 120-130t / d of tar byproducts, and the actual processing capacity of the incinerator currently in operation is 70t / d. At the same time, the incinerator must be stopped for cleaning every 15 days or so, and at least 85t of waste liquid needs to be processed every day.

[0024] The former thermal power operation department carried out waste liquid mixing combustion in two air separation boilers for nearly a year. Figure 1 As shown, many problems occurred during the trial firing, including damage to three water pumps, accumulation of solid matter more than 3 meters high in the liquid storage tank, blockage of tar pipelines, large-area coking in the furnace, agglomeration caused by electrostatic precipitator, high-temperature corrosion of the heating surface tubes and serious lag in steam temperature regulation, etc. These problems eventually led to the cessation of the co-firing operation.

[0025] In response to the above problems, according to Figure 2 The specific contents of the technical transformation are as follows:

[0026] 1. Analyze the waste liquid elements and ash characteristics generated by the thermal power plant, including elemental analysis of the waste liquid (carbon, hydrogen, oxygen, nitrogen, sulfur, potassium, sodium), component content analysis of components such as ash and moisture, ash characteristics analysis after complete combustion of the waste liquid (softening, deformation and melting temperature of the ash, etc.), and physical characteristics analysis of the waste liquid (flash point, ignition point, freezing point and calorific value, etc.), and use the obtained data to guide the physical structure design of the spray gun.

[0027] 2. Directly change the original vertical tank to a horizontal tank. The temporarily added external heating power is small and cannot achieve the expected heating effect. There are still more than 3 meters high of condensates in the liquid storage tank that have not been treated. Therefore, first, clean the condensates in the tank, add internal heating equipment in the liquid storage tank, lower the outlet of the liquid storage tank, and add a maintenance discharge port; add a waste liquid recirculation system. Temporarily connect the drain to the original drain pipe, reserve a spare outlet, and later, part or all of the drain can be directly discharged into the liquid storage tank to recover the energy of the drain, or an existing liquid storage tank can be found or a new tank can be made.

[0028] 3. According to the viscosity data provided by the thermal power plant, design the waste liquid temperature to be higher than 90 °C. Considering the influence of water evaporation, the waste liquid temperature of the entire process should be controlled within the range of 85 °C to 95 °C. At the same time, install 2 temperature measurement points and 1 pressure measurement point in the tank.

[0029] 4. The absorption of expansion by the waste liquid and steam pipes depends on elbows. All or part of the waste liquid pipes are heated by sleeves. The pipes involved include the following parts: the material of the heating pipe is 304L stainless steel; the original pipe for transporting the waste liquid is blocked and needs to be re-laid, with an estimated length of 350 meters; add about 60 meters of steam pipes for the steam atomizing spray gun, and add a temperature measurement point at the spray gun inlet; the original steam heating pipe needs to be renovated and run in parallel with the pipe for transporting the waste liquid, with an estimated length of 100 meters, and install a temperature measurement point at the outlet of the steam heating pipe; in order to prevent the accumulation of waste liquid in the pipe from solidifying and blocking the pipe, the pipe and the system should be purged during the furnace shutdown period, and add a steam purging pipe, about 50 meters.

[0030] 5. Add steam pipes for the steam atomizing spray gun, and add a temperature measurement point at the spray gun inlet; install pressure measurement points and regulating valves at both the pump outlet and the spray gun inlet, install a temperature measurement point at the pump outlet, and use steam tracing for the waste liquid pipes. For convenient maintenance, the pipes for transporting the waste liquid are connected by flanges every 20m.

[0031] 6. The spray gun needs to be redesigned. Prepare to design a steam atomizing spray gun. Install temperature, pressure measurement points and regulating valves on both the steam and waste liquid pipes at the spray gun inlet; set 2 spray guns, introduce them from the secondary air or primary air, and the designed flow rate of the spray gun is 500 - 800 kg / H, and the flow rate can be increased later according to the situation; the spray gun needs brackets and tracks. For convenient maintenance, the pipes for transporting the waste liquid are connected by flanges every 20 meters, with an estimated 8 pairs of flanges.

[0032] 7. Design an atomization experiment. According to the results of the atomization experiment, a direct-injection pressure-type atomizing nozzle is adopted for the atomizing spray gun. The spray torch is in the shape of a hollow cone, with a spray angle of 60°, a flow rate of 30 L / min, a nozzle pressure of 15 MPa, and an area ratio of 0.0223.

[0033] After the transformation, the water pump of the thermal power plant operates well. The solid substances accumulated in the liquid storage tank are significantly reduced, the tar pipeline is not blocked, the problem of furnace coking is greatly improved, a large amount of caking no longer occurs in the electrostatic precipitator, the high-temperature corrosion of the heating surface pipes is reduced, and the steam temperature regulation returns to the normal level.

[0034] Through the transformation of this method, the combustion system is optimized, the structure of the spray gun is improved, the safe and efficient co-incineration of waste liquid is realized, the upstream production is guaranteed, the economic cost of the thermal power plant is reduced, resources are saved, and it has extremely high economic benefits and environmental protection value, providing an effective guarantee for BDO production. Therefore, the present invention has great practical value and can achieve relatively ideal technical effects.

[0035] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0036] Although the present invention has been disclosed above by way of examples, it is not intended to limit the protection scope of the present invention. Any modification and retouching made by those skilled in the art without departing from the concept and scope of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for improving the co-combustion of waste liquid in a thermal power plant, characterized in that specifically As follows: 1) Conduct waste liquid element analysis and ash property analysis on the waste liquid generated by the thermal power plant; including element analysis of the waste liquid, component content analysis of ash and moisture components, ash property analysis after complete combustion of the waste liquid, and physical property analysis of the waste liquid; use the obtained data to guide the physical structure design of the spray gun. The inlet of the spray gun is connected to the liquid storage tank and is equipped with a pump, and the outlet of the spray gun is arranged in the furnace; 2) Clean the condensate in the liquid storage tank; set an internal heating device in the liquid storage tank and connect it to the steam source; lower the outlet of the liquid storage tank and set a maintenance discharge port; temporarily connect the hydrophobic to the original hydrophobic pipeline and reserve a spare outlet. Later, part or all of the hydrophobic is directly discharged into the liquid storage tank to recover the energy of the hydrophobic, or find an existing liquid storage tank or make a new tank; 3) Add a waste liquid recirculation system; considering the influence of water evaporation, control the waste liquid temperature of the entire process within the range of 85°C to 95°C. At the same time, set multiple temperature measurement points and pressure measurement points in the liquid storage tank; 4) The waste liquid pipeline and the steam pipeline absorb expansion by elbows. All or part of the waste liquid pipeline is heated by a sleeve, and the heating pipe material is stainless steel; rearrange the pipeline for transporting waste liquid. The original steam heating pipeline is transformed to run in parallel with the pipeline for transporting waste liquid, and a temperature measurement point is set at the outlet of the steam heating pipeline; in order to prevent the pipeline from accumulating waste liquid and solidifying to block the pipeline, purge the pipeline and the system during the furnace shutdown period, and add a steam purge pipeline; 5) Add a steam pipeline to the steam atomizing spray gun and set a temperature measurement point at the inlet of the spray gun; set pressure measurement points and regulating valves at both the pump outlet and the spray gun inlet, set a temperature measurement point at the pump outlet, and use steam tracing for the waste liquid pipeline; for convenient maintenance, use flange connections for the pipeline transporting waste liquid; 6) Redesign the spray gun. Set temperature measurement points, pressure measurement points, and regulating valves on both the steam pipeline and the waste liquid pipeline at the inlet of the spray gun; set multiple spray guns and introduce them from the secondary air or primary air. The designed flow rate of the spray gun depends on the atomization experiment; 7) In order to ensure complete combustion of the waste liquid and prevent high-temperature corrosion, determine the atomization method of the nozzle, as well as the flow parameters and structural parameters of the nozzle, and conduct waste liquid spray tests based on this to provide technical support for the industrial operation of the waste liquid.

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