A coking inhibitor for waste heat boilers

Abstract

The present invention relates to a coking inhibitor for waste heat boilers, belonging to the technical field of ash cleaning for smelting equipment. The components of the coking inhibitor for waste heat boilers of the present invention include: asbestos powder, manganese dioxide, aluminum oxide and ammonium carbonate. The present invention can control the coking thickness of the convection tube bundle and there is a peeling phenomenon, slow down the growth rate of the coke body, effectively solve the adhesion problem of the flue gas system of the fluidized bed boiler waste heat boiler, and reduce the safety and environmental protection risks.

Description

Technical Field

[0001] The invention belongs to the technical field of dust cleaning for smelting equipment. Specifically, it relates to a coking inhibitor for waste heat boilers. Background Art

[0002] In the fluidized bed furnace of the roasting branch factory of Yunnan Yongchang Lead-Zinc Co., Ltd., due to factors such as increased production load, equipment aging, complex raw materials, and process control, the convective tube bundles and ash hoppers of the waste heat boiler of the fluidized bed furnace are severely fouled with ash. It cannot be completely eliminated by existing process means. As the ash accumulation gradually increases, large lumps will continuously adhere to the tube bundles and membrane walls, and in severe cases, the tube bundles will be bonded into a single piece, hindering the flow of flue gas. Due to the high hardness of the coke blocks and the high flue gas temperature at the coking sites, manual cleaning is labor-intensive and poses a significant safety hazard; at the same time, when the blockage is severe, environmental protection risks increase due to flue gas leakage. Generally, after running for a period of time, the load needs to be reduced for on-line cleaning, but the cleaning is difficult and incomplete, and there are hidden dangers such as safety and environmental protection. At the same time, it causes production discontinuity or load reduction, having a serious impact on production. For example, long-term load reduction for coke cleaning restricts continuous production, reduces operation efficiency, and results in low comprehensive benefits; the work intensity of coke cleaning and ash removal is high, and due to the characteristics of dense, hard, and adhesive coke blocks, the relevant industries generally use manual cleaning and blasting cleaning, with extremely high cleaning difficulty; the coke cleaning operation environment is high-temperature, dusty, and has a narrow space, and even measures such as suspension and scaffolding are required, and there are often phenomena of coke falling, which may injure and scald the cleaning personnel, with great safety hazards; due to the shortened continuous operation time, poor furnace conditions, and low load, production capacity losses are incurred.

[0003] The coking and ash removal of waste heat boilers also bring the following problems: During the ash removal process, the air supply volume must be reduced to 3500 Nm³ / h, and the processing capacity of the fluidized bed furnace decreases by 60%; the ash removal frequency needs to be once every 1 - 2 days, and each time it takes 1.5 - 2.0 h. The ash removal affects the metal input to the system by 2 metric tons per hour; and frequent ash removal of the waste heat boiler caking causes unstable operation of the fluidized bed furnace, with large fluctuations in the air box pressure, posing a great risk of stable operation; the ash removal process causes air to enter the flue gas pipeline, resulting in a decrease in sulfur concentration and a reduction in the sulfuric acid conversion temperature, and an electric furnace must be used for heating, leading to an increase in the unit power consumption of sulfuric acid; the ash removal process increases the personnel configuration and has a high labor intensity, which is not conducive to reducing labor costs. Summary of the Invention

[0004] In order to overcome the problems existing in the background art, the invention provides a coking inhibitor for waste heat boilers, which can control the coking thickness of the convective tube bundles and has a peeling phenomenon, slow down the growth rate of the coke body, effectively solve the adhesion problem of the flue gas system of the waste heat boiler of the fluidized bed furnace, and reduce safety and environmental protection risks.

[0005] To achieve the above object, the invention is realized through the following technical solutions:

[0006] The components of the coking inhibitor for waste heat boilers include: asbestos powder, manganese dioxide, aluminum oxide and ammonium carbonate.

[0007] Preferably, the coking inhibitor comprises the following components in mass percentages: 45 - 55% of asbestos powder, 8 - 12% of manganese dioxide, 32 - 38% of aluminum oxide and 3 - 7% of ammonium carbonate.

[0008] Preferably, the coking inhibitor is sprayed into the waste heat boiler from the top of the slope connecting the fluidized bed furnace and the waste heat boiler using compressed air, and is added through a single hole and a single pipe, and follows the flue gas to the coking site.

[0009] Preferably, the coking inhibitor is added intermittently, and the addition amount is 80 - 120 kg per day.

[0010] Preferably, the addition frequency of the coking inhibitor is 4 - 8 times per day, and each time is 20 - 40 minutes.

[0011] The present invention enhances the oxidation atmosphere, enables the unreacted substances to react fully, thereby forming stable compounds or separating them, so as to achieve the purpose of reducing the formation of low - melting - point eutectics of incomplete products and ammonium carbonate substances in soot; enables the ash slag to be quickly solidified, obtaining a dry, brittle and non - adherent high - melting - point compound, preventing the deposit from growing further; and forms an unstable splitting surface inside the ash slag, which can be easily removed by its own gravity, vibration or flue gas shear force, and will not form large slag blocks, thus playing an inhibitory role on coking.

[0012] The beneficial effects of the present invention:

[0013] The present invention can inhibit the coking of the convection tube bundles of waste heat boilers, slow down the growth rate of coke bodies, make the internal structure of coke bodies fluffy and easy to peel off, can extend the coking cleaning cycle to 4 days, shorten the ash cleaning operation time to within one hour, extend the ash cleaning cycle, shorten the ash cleaning operation time of workers, reduce the cleaning difficulty, reduce the specific power consumption of sulfuric acid, and generate good economic benefits. Detailed implementation manners

[0014] In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate the understanding of those skilled in the art.

[0015] The described waste heat boiler coking inhibitor comprises components in the following mass percentages: asbestos powder 45 - 55%, manganese dioxide 8 - 12%, aluminum oxide 32 - 38%, and ammonium carbonate 3 - 7%. It is sprayed into the waste heat boiler from the top of the slope where the fluidized bed furnace is connected to the waste heat boiler using compressed air, and is added through a single hole and a single pipe. It goes with the flue gas to the coking site and is added intermittently. The addition amount is 80 - 120 kg per day, the addition frequency is 4 - 8 times per day, and each addition lasts for 20 - 40 minutes. After the coking inhibitor is added to the waste heat boiler, it produces a catalytic oxidation effect, making the reaction more complete and sufficient, quickly solidifying the ash slag to obtain a dry, brittle, and non - adherent high - melting - point compound, preventing the deposit from growing further; and forming an unstable splitting surface inside the ash slag, which can be easily removed by its own gravity, vibration, and flue gas shear force, etc., without forming large slag blocks, thus playing an inhibitory role on coking.

[0016] Example 1

[0017] The waste heat boiler coking inhibitor is sprayed into the waste heat boiler from the top of the slope where the fluidized bed furnace is connected to the waste heat boiler using compressed air, and is added through a single hole and a single pipe. The waste heat boiler coking inhibitor comprises components in the following mass percentages: asbestos powder 48%, manganese dioxide 10%, aluminum oxide 35%, and ammonium carbonate 7%. The waste heat boiler coking inhibitor is added intermittently. The addition amount is 100 kg per day, the addition frequency is 4 times per day, and each addition lasts for 30 minutes. It is added continuously for 9 days. During this period, the coking situation of the convection tube bundle is checked. It can be seen that the amount of coking on the convection tube bundle has not increased further, the existing old coking has not grown larger, and there is a peeling phenomenon. The coke body is taken from the site, and the coke body has obvious stratification, with a fracture layer formed inside and is relatively loose. The ash cleaning cycle is extended by one day compared with when the present invention is not used, the ash cleaning time is shortened by one hour, and the ash cleaning difficulty is reduced.

[0018] Example 2

[0019] The waste heat boiler coking inhibitor is sprayed into the waste heat boiler from the top of the slope where the fluidized bed furnace is connected to the waste heat boiler using compressed air, and is added through a single hole and a single pipe. The waste heat boiler coking inhibitor comprises components in the following mass percentages: asbestos powder 50%, manganese dioxide 10%, aluminum oxide 35%, and ammonium carbonate 5%. The waste heat boiler coking inhibitor is added intermittently. The addition amount is 110 kg per day, the addition frequency is 4 times per day, and each addition lasts for 40 minutes. It is added continuously for 9 days. During this period, the coking situation of the convection tube bundle is checked. It can be seen that the amount of coking on the convection tube bundle has not increased further, the existing old coking has not grown larger, and there is a peeling phenomenon. The coke body is taken from the site, and the coke body has obvious stratification, with a fracture layer formed inside and is relatively loose, and the structure is fluffy. The ash cleaning cycle is extended by one day compared with when the present invention is not used, the ash cleaning time is shortened to within one hour, and the ash cleaning difficulty is reduced.

[0020] Example 3

[0021] Inject the coking inhibitor for waste heat boiler from the top of the slope connecting the fluidized bed furnace and the waste heat boiler using compressed air. Add it through a single hole and a single pipe. The coking inhibitor for waste heat boiler comprises the following components by mass percentage: asbestos powder 55%, manganese dioxide 8%, aluminum oxide 32% and ammonium carbonate 5%. The coking inhibitor for waste heat boiler is added intermittently, with an addition amount of 120 kg per day, an addition frequency of 8 times per day, and each addition lasting for 20 minutes. Continuously add it for 9 days. During this period, check the coking situation of the convection tube bundle. It can be seen that the amount of coking on the convection tube bundle has not increased, the existing old coking has not grown larger, and there is a phenomenon of peeling. Take the coke body from the site. The coke body has an obvious layered phenomenon and a fluffy structure. The ash cleaning cycle is extended by one day compared with that without using the present invention, the ash cleaning time is shortened by one hour, and the ash cleaning difficulty is reduced.

[0022] According to the historical production situation, due to the ash accumulation problem, the 10-square-meter fluidized bed furnace of the Roasting Branch of Yunnan Yongchang Lead-Zinc Co., Ltd. reduces the load for ash cleaning about 23.63 hours per month. The annual impact on the metal output is 171.12 t in total, and the sulfuric acid output is 293.4 t. The relevant annual income loss caused by the load reduction is about 793,858 yuan. After using the present invention, the annual increased income is about 59,435.76 yuan. Due to frequent ash cleaning and the ash adhering to the pipe wall, the artificial method of hitting the tube bundle causes great damage to the tube bundle and the boiler, there are great potential safety hazards and environmental protection problems. After using the coking inhibitor, the production cycle is extended, and at the same time, great protection is formed for the tube bundle and the boiler, and the service life of the boiler tube bundle is extended.

[0023] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in terms of form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A coking inhibitor for waste heat boilers, characterized in that: The coking inhibitor comprises the following components by mass percentage: asbestos powder 45-55%, manganese dioxide 8-12%, aluminum oxide 32-38% and ammonium carbonate 3-7%.

2. The coking inhibitor for waste heat boilers according to claim 1, wherein: The coking inhibitor comprises the following components by mass percentage: asbestos powder 50%, manganese dioxide 10%, aluminum oxide 35% and ammonium carbonate 5%.

3. The coking inhibitor for waste heat boilers according to any one of claims 1-2, characterized in that: The coking inhibitor is sprayed into from the top of the slope where the fluidized bed furnace is connected to the waste heat boiler by compressed air, and is added by single hole and single pipe, and goes to the coking place along with the flue gas.

4. The coke deposition inhibitor for waste heat boilers according to claim 3, wherein: The coking inhibitor is added intermittently, and the addition amount is 80-120 kg per day.

5. The coking inhibitor for waste heat boilers according to claim 4, characterized in that: The addition frequency of the coking inhibitor is 4-8 times per day, and each time is 20-40 minutes.