Polymer biomass and catalyst combined denitration system suitable for gas boiler

Abstract

The utility model discloses a macromolecule biomass and catalyst combined denitration system suitable for a gas boiler. The macromolecule biomass and catalyst combined denitration system comprises a reducing agent storage and supply system, a dilution water system, a metering and mixing system, a reducing agent injection system and a catalyst system. The high-molecular biomass reducing agent is supplied by the reducing agent storage and supply system, is mixed with water provided by the dilution water system in the metering and mixing system, is sprayed into a high-temperature area at the inlet end of the horizontal flue of the boiler through the high-molecular biomass reducing agent spraying inlet, is mixed with flue gas flowing through the horizontal flue of the boiler, and is subjected to reduction reaction with NOx in the flue gas; further, nitric oxide in the flue gas is removed. The flue gas which does not meet the denitration emission requirement continues to advance, passes through the corner of the horizontal flue and is transferred to the tail flue, in the period, the flue gas sequentially passes through all the heating surfaces and then enters the area of the catalyst arrangement layer, under the action of the catalyst, the unreacted macromolecular biomass reducing agent is subjected to the reduction reaction with NOx again, and NOx in the flue gas is further removed.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology, and in particular to a combined denitrification system of polymer biomass and catalyst suitable for gas boilers. Background Technology

[0002] Environmental requirements for boiler flue gas emissions are becoming increasingly stringent. To ensure that the concentration of nitrogen oxides in the flue gas meets the ultra-low emission requirements, although low-NOx combustion technology is simple and feasible, its control capabilities are limited and cannot meet the current ultra-low emission requirements. In addition, the modification of the combustion chamber and burner is not feasible, so SCR denitrification systems are generally installed at the back end for NOx treatment.

[0003] Currently, the reducing agents used in flue gas SCR denitrification processes are mainly ammonia water, urea, and liquid ammonia (which are rarely used in China). Regardless of the reducing agent used, the actual active component is NH3. The reducing agent needs to be stored in a sealed container, which poses certain risks and safety issues. The ammonia produced by the reaction can easily lead to secondary pollution. Moreover, this process has high operating costs and requires a large initial investment. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model designs a combined denitrification system of polymer biomass and catalyst suitable for gas boilers.

[0005] The present invention adopts the following technical solution:

[0006] A combined denitrification system using polymeric biomass and catalyst suitable for gas boilers includes a reducing agent storage and supply system, a dilution water system, a metering and mixing system, a reducing agent injection system, and a catalyst system.

[0007] The reducing agent storage and supply system is used to store high molecular weight biomass reducing agents;

[0008] The dilution water system is used to supply water for dissolving and diluting high-molecular-weight biomass reducing agents;

[0009] The metering and mixing system is used for mixing, dissolving, and diluting polymeric biomass reducing agents and water;

[0010] The reducing agent injection system is used to inject the mixed, dissolved and diluted polymeric biomass reducing agent into the polymeric biomass reducing agent inlet located at the inlet end of the boiler's horizontal flue.

[0011] The catalyst system includes a catalyst layer, which consists of the catalyst and its supporting steel frame, and is located at the tail end of the vertical flue after the horizontal flue of the boiler.

[0012] The high-molecular-weight biomass denitrification system injects a high-molecular-weight biomass reducing agent into the high-temperature zone of the boiler, where it reacts with NOx to produce N2 and water. The medium-low temperature catalyst denitrification system utilizes a catalyst at a specific temperature (150-450℃) to reduce NOx in the flue gas by mixing it with the high-molecular-weight biomass reducing agent, producing nitrogen and water, thereby reducing NOx emissions. Flue gas that does not meet denitrification emission requirements enters the reactor containing the catalyst after being rectified and mixed through various stages of heating surfaces. In this zone, the unreacted high-molecular-weight biomass reducing agent reacts again with NOx, further removing NOx from the flue gas, ensuring that the boiler's final NOx emissions meet standards.

[0013] Preferably, the metering and mixing system includes a mixing pump, a mixing tank, a distribution module, measuring instruments, and supporting flushing pipeline equipment.

[0014] Preferably, the injection inlet of the polymeric biomass reducing agent is located in the 650℃-950℃ temperature range at the inlet end of the boiler's horizontal flue.

[0015] Preferably, the reducing agent spraying system includes a polymer biomass spray gun and supporting equipment.

[0016] Preferably, the polymeric biomass reducing agent is injected into the horizontal flue and, after being gasified at high temperature, is fully and uniformly mixed with the flue gas. The mixing residence time of the polymeric biomass reducing agent and the flue gas is ≥0.2S before reaching the catalyst layer.

[0017] Preferably, the system also includes a control system, which consists of a control cabinet and field measuring instruments, and is respectively connected to the reducing agent storage and supply system, the dilution water system, the metering and mixing system, and the reducing agent injection system.

[0018] Preferably, the supporting steel frame is horizontally fixed within the vertical flue frame of the boiler. It is arranged perpendicular to the flue gas direction and equipped with baffles around its perimeter to prevent flue gas from escaping.

[0019] Preferably, the polymeric biomass spray gun includes a stainless steel gun body, a liquid inlet, a compressed air inlet, and an atomizing nozzle. Polymeric biomass diluted to a specific concentration is transported to the liquid inlet via a liquid pipe, and then, under the purging of compressed air, is transported to the polymeric biomass reducing agent inlet and enters the horizontal flue.

[0020] The beneficial effects of this invention are as follows: Compared to traditional boiler flue gas SCR denitrification processes, this invention uses an ammonia-free reducing agent formula and an ammonia-free organic denitrification method, which is green, environmentally friendly, and operates without ammonia, thus avoiding ammonia escape and its adverse effects at the source, and eliminating the safety issues associated with storing liquid ammonia and other reducing agents. This system removes NOx through multi-zone, staged reactions, achieving ultra-low NOx emissions even when the boiler is operating at low load, maximizing the removal of NOx from the flue gas. This system also consumes less denitrification agent, resulting in lower operating costs in the later stages. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of this utility model;

[0022] In the diagram: 1. Reducing agent storage and supply system, 2. Dilution water system, 3. Metering and mixing system, 4. High molecular weight biomass reducing agent injection port, 5. Superheater, 6. Evaporator, 7. Economizer, 8. Catalyst arrangement layer. Detailed Implementation

[0023] The technical solution of this utility model will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0024] Example: Figure 1 As shown, a combined denitrification system using polymeric biomass and catalyst suitable for gas-fired boilers includes a reducing agent storage and supply system 1, a dilution water system 2, a metering and mixing system 3, a reducing agent injection system, and a catalyst system. The polymeric biomass reducing agent is supplied by the reducing agent storage and supply system and mixed with water supplied by the dilution water system in the metering and mixing system. It is then injected into the high-temperature zone at the inlet end of the boiler's horizontal flue through the polymeric biomass reducing agent injection inlet 4, mixing with the flue gas flowing through the horizontal flue and undergoing a reduction reaction with NOx in the flue gas, thereby removing nitrogen oxides from the flue gas. Flue gas that does not meet the denitrification emission requirements continues to travel, passing through a bend in the horizontal flue and turning to the tail flue. During this process, the flue gas sequentially passes through a superheater 5, an evaporator 6, and an economizer 7 for rectification and mixing before entering the reactor area of ​​the catalyst layer 8 in the catalyst system. In this area, under the action of the catalyst, the unreacted polymeric biomass reducing agent undergoes another reduction reaction with NOx, further removing NOx from the flue gas, ensuring that the final NOx emission from the boiler flue gas meets the standards.

[0025] The selection of the injection inlet location for the high-molecular-weight biomass reducing agent in this system needs to meet the requirements of a biomass reducing agent reaction temperature of 680℃-950℃ and a residence time of ≥0.2S between the biomass reducing agent and flue gas. Experiments have confirmed that for loads below 80t, selecting the injection inlet location 21m from the front wall (where the temperature is approximately 850℃) achieves a denitrification efficiency of around 35%. For loads above 80t, selecting the injection inlet location after the high-pressure superheater and before the low-pressure superheater (for boilers with high-pressure superheaters and obvious flames in the furnace, which are unsuitable for high-molecular-weight reducing agent gasification conditions) results in a denitrification efficiency of around 10%. Except for the injection inlet location, both methods are identical. Calculations of the boiler flue gas flow field and velocity show that the time for the biomass reducing agent to reach the catalyst after decomposition, through rectification in the superheater, evaporator, and economizer, is 0.84S, meeting the requirement of a gasification residence time ≥0.2S, ensuring thorough and uniform mixing of the gasified biomass reducing agent with the flue gas. The reactor zone is located between the economizer and the air preheater in the boiler's tail flue. Inside the reactor, the catalyst support frame, various reinforcing plates, and supports are designed to prevent ash accumulation. Thermal expansion compensation measures are also considered. Based on the characteristics of the boiler flue gas composition, a suitable structural form is selected, and the catalyst is designed with measures to prevent ash blockage and poisoning, while minimizing pressure loss to avoid affecting the overall boiler operation. Furthermore, the catalyst module is designed with an effective sealing system to prevent flue gas short-circuiting. The catalyst layer arrangement meets flow field requirements, the reducing agent supply can meet the requirements of different boiler loads, and the metering and distribution system is equipped with a reliable control system that is convenient, flexible, and reliable for adjustment.

[0026] The working principle of this invention is as follows: a high-molecular biomass reducing agent is injected into the high-temperature zone of the boiler through a selected nozzle, and reacts with NOx in the flue gas to generate nitrogen and water. The flue gas that does not meet the denitrification emission requirements is rectified and mixed through each heating surface, and then enters the catalyst arrangement layer in the reactor area again. Under the action of the catalyst, the NOx in the flue gas is removed after being mixed with the high-molecular biomass reducing agent and undergoing a reduction reaction, thereby reducing the NOx emission and ultimately achieving ultra-low NOx emissions from the boiler flue gas.

[0027] Compared to traditional methods that use ammonia as a reducing agent for boiler flue gas denitrification, this invention employs an ammonia-free reducing agent formula, eliminating ammonia escape and its adverse effects at the source, preventing secondary pollution, and avoiding the safety issues associated with hazardous chemical storage. This system utilizes a high-molecular-weight biomass reducing agent to react with NOx in stages within the furnace at high, medium, and low temperatures. Through a rationally arranged catalyst layer, it fully utilizes each stage for NOx removal. This system consumes less denitrification agent, has low operating costs, high denitrification efficiency, and avoids corrosion and crystallization problems of NH4HSO4 on the boiler's tail heating surfaces, maximizing the removal of nitrogen oxides from boiler flue gas.

[0028] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. A high-molecular biomass and catalyst combined denitration system suitable for coal gas boilers, characterized in that, It includes a reducing agent storage and supply system, a dilution water system, a metering mixing system, a reducing agent injection system and a catalyst system. The reducing agent storage and supply system is used to store the high-molecular biomass reducing agent. The dilution water system is used to supply water for dissolving the high-molecular biomass reducing agent. The metering mixing system is used to mix and dissolve the high-molecular biomass reducing agent and water. The reducing agent injection system is used to inject the mixed and dissolved high-molecular biomass reducing agent into the high-molecular biomass reducing agent injection port arranged at the inlet end of the horizontal flue of the boiler. The catalyst system includes a catalyst layer composed of catalysts and their supporting steel frames, which is arranged at the tail end of the vertical flue behind the horizontal flue of the boiler.

2. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, The metering mixing system includes a mixing pump, a mixing tank, a distribution module, a measuring instrument and a matching flushing pipeline device.

3. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, The high-molecular biomass reducing agent injection port is located in the temperature area of 650-950℃ at the inlet end of the horizontal flue of the boiler.

4. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, The reducing agent injection system includes a high-molecular biomass injection gun and a matching device.

5. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, The high-molecular biomass reducing agent injected into the horizontal flue is fully and uniformly mixed with the flue gas after gasification at high temperature, the mixing residence time of the high-molecular biomass reducing agent and the flue gas is ≥0.2S, and then reaches the catalyst layer.

6. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, A control system is further included, which is composed of a control cabinet and field measuring instruments, and is respectively communicatively connected with the reducing agent storage and supply system, the dilution water system, the metering mixing system and the reducing agent injection system.

7. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 1, characterized in that, The supporting steel frames are horizontally fixed in the vertical flue frame of the boiler.

8. The polymer biomass and catalyst combined denitration system suitable for coal gas boiler according to claim 4, characterized in that, The high-molecular biomass injection gun includes a stainless steel gun body, a liquid inlet, a compressed air inlet and an atomizing nozzle.

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