CN103881757B - Fixed-bed gasification and comprise its treatment system, refuse processing method - Google Patents

Abstract

The invention discloses a fixed-bed gasification device, a waste treatment system including the same, and a waste treatment method. A fixed-bed gasification device, comprising a gasification chamber, a waste inlet, a solid-liquid outlet, a first gas inlet, a gas outlet, and at least one second gas inlet; the waste inlet is located in the gasification chamber The top of the body is connected with the inside of the gasification chamber; the solid-liquid outlet is set at the bottom of the gasification chamber and communicated with the inside of the gasification chamber, and the solid-liquid outlet is the solid-liquid outlet; the first gas inlet is set at the gasification chamber The lower part of the gasification chamber is connected with the gasification chamber. The second gas inlet is set in the middle of the gasification chamber; breath. The use of the fixed-bed gasification device of the present invention to treat organic waste is highly efficient and environmentally friendly, and the export synthesis gas does not contain tar.

Description

Fixed-bed gasification device, treatment system including same, waste treatment method

technical field

The invention relates to a fixed-bed gasification device, a waste treatment system including the same, and a waste treatment method.

Background technique

In recent years, with the rapid development of economy and society, a large amount of organic waste is produced in my country every year and needs to be treated urgently. There are many types of solid waste containing organic matter, common ones are: municipal waste, medical and pharmaceutical waste, polluted soil, industrial solid waste and agricultural waste. The composition of organic waste is very complex, highly perishable, emits foul odor, and often contains pathogenic bacteria and parasites, as well as heavy metals such as cadmium, mercury, chromium, and lead, as well as persistent organic pollution such as polycyclic aromatic hydrocarbons, pesticides, and organic chlorine. Improper handling can easily cause serious environmental pollution.

With the increasingly severe global ecological problems, the development trend of organic waste reduction, harmlessness and resource utilization has become a general consensus and a new research hotspot. At present, the existing organic waste treatment methods in my country mainly include landfill, agricultural composting and incineration. When landfilling, it is easy to pollute the groundwater environment and emit a large amount of methane and other greenhouse gases. Agricultural composting has the problem of soil pollution by harmful components such as heavy metals. Through incineration, the reduction can be achieved quickly and to a large extent, and the heat energy of organic matter is used; however, pollutants such as SO2 and NOx will be emitted during incineration, and organic pollutants such as dioxins will also be produced. Pyrolysis and gasification technology (JP20010127739, CN201120341172.7, CN201120552371.2) overcomes the shortcomings of incineration. This technology can convert organic matter in waste into fuel gas, oil, etc., while maintaining its atmosphere in an oxygen-free or reducing state , will not produce SO ₂ , NO _x and dioxins, etc.

Due to the irregular shape of organic waste, it is difficult to make pulp and powder. Therefore, the use of entrained bed and fluidized bed gasification technology requires a complicated pretreatment process, and it is difficult to have good economic benefits. The fixed bed gasifier has the advantages of simple feeding, small investment and simple operation, and is suitable for treating organic waste. However, the internal temperature gradient of the conventional fixed-bed gasifier is relatively large, and it can be simply divided into ash layer, combustion layer, gasification layer and drying layer from bottom to top. In this way, when processing leather waste containing heavy metal chromium, chromium is converted into highly toxic hexavalent chromium in the high-temperature oxidation environment of the combustion layer, and then discharged through the ash layer, causing serious pollution. At the same time, the export synthesis gas contains tar, etc., and also produces difficult-to-treat wastewater containing phenol, causing serious pollution. Therefore, in order to apply the fixed bed gasification technology to the gasification of organic waste, the gasification process and the structure of the fixed bed gasifier must be improved.

Contents of the invention

The technical problem to be solved by the present invention is to overcome that most of the organic waste treatment methods in the prior art adopt simple incineration treatment, and the discharge content of harmful substances such as dioxins and leached heavy metals in the waste gas waste residue is difficult to reach the standard; a few use fixed bed The equipment treats organic waste, but the export synthesis gas contains tar, and the ash contains a large amount of toxic hexavalent chromium, which produces difficult-to-treat phenol-containing wastewater and serious environmental pollution. Provide an efficient and environmentally friendly fixed-bed gasification device and Including its waste treatment system and waste treatment method.

The invention provides a fixed-bed gasification device, which includes a gasification chamber, a waste inlet, a solid-liquid outlet, a first gas inlet, a gas outlet, and at least one second gas inlet; the waste The inlet is located at the top of the gasification chamber and communicates with the interior of the gasification chamber; the solid-liquid outlet is located at the bottom of the gasification chamber and communicates with the interior of the gasification chamber. The solid-liquid outlet is Solid liquid outlet; the first gas inlet is set at the lower part of the gasification cavity and communicated with the gasification cavity, and the second gas inlet is set at the middle of the gasification cavity; the second gas The vertical distance between the inlet and the first gas inlet, and the height ratio of the gasification chamber are 0.4-0.8; the gas outlet is located above the gasification chamber and communicates with the inside of the gasification chamber , the gas outlet is a synthesis gas outlet.

In the present invention, preferably, when the number of the second gas inlets is 2 or more, several of the second gas inlets are equiangularly evenly distributed in the middle of the gasification chamber on the same level.

In the present invention, preferably, the ratio between the vertical distance between the second gas inlet and the first gas inlet and the height of the gasification chamber is 0.5-0.6.

Preferably, the waste inlet is provided with a distributor. The organic waste to be treated falls evenly into the gasification chamber through the distributor to ensure full contact with oxygen.

Preferably, the inner wall of the gasification chamber is provided with a water-cooled jacket device for heat preservation, so as to avoid damage due to excessive temperature. The water-cooled jacket device is a conventional device used in the fixed-bed gasification device in the field.

Preferably, a grate is provided in the lower part of the gasification chamber, and the grate is located above the first gas inlet. The grate can better guide the gas introduced by the first gas inlet into the gasification chamber, and facilitate the uniform discharge of solid waste. The grate is preferably insulated with a water-cooled jacket device to avoid damage due to excessive temperature.

The present invention also provides a waste treatment system, including a waste preprocessor, at least one lock bucket, a fixed bed gasification device as described above, a heat exchanger, a dust removal device, and a desulfurization purification device; The waste preprocessor, the lock hopper and the waste inlet are connected in sequence; the gas outlet is connected in sequence with the heat exchanger, the dust removal equipment and the desulfurization purification equipment.

Preferably, the waste treatment system further includes an ash hopper, and the ash hopper is connected to the solid-liquid outlet.

The present invention also provides a waste treatment method, which includes the following steps:

The pretreated waste is fed to the fixed bed gasification device, mixed with the mixed gas containing oxygen, and subjected to a flameless oxidation reaction to obtain synthesis gas and solid waste residue; wherein, the gas containing oxygen The mixed gas meets the requirement that the oxygen volume percentage does not exceed 15%.

In the present invention, the wastes are organic wastes treated by conventional gasification reactions in the field, generally solid wastes with high calorific value such as tanning solid wastes and medical wastes, especially those containing heavy metals and long-lasting Organic wastes such as permanent organic pollutants are better treated by the method of the present invention. The organic waste is preferably one or more of tanning scraps, medical absorbent cotton, gauze, masks, latex products, medicines and polypropylene material products.

In the present invention, the mixed gas containing oxygen can generally be air with low oxygen content filled with nitrogen, water vapor or carbon dioxide. The mixed gas is preferably one or more of flue gas, steam and carbon dioxide mixed with oxygen. Flue gas, steam or carbon dioxide can also participate in the gasification reaction in the fixed-bed gasification device to produce hydrogen and carbon monoxide, which can increase the content of active components in the final product synthesis gas.

In the present invention, preferably, the ratio of the amount of oxygen in the mixed gas entering the first gas inlet to the total amount of oxygen in the mixed gas entering the second gas inlet is 3:1-10: 1, preferably 4:1-6:1.

In the present invention, preferably, the molar ratio of oxygen atoms in the oxygen to carbon atoms in the waste is 1:1.

Preferably, the superficial gas velocity in the gasification chamber is less than 1 m/s.

Preferably, the reaction temperature inside the gasification chamber is preferably ≥900°C, more preferably ≥1000°C; the working pressure inside the gasification chamber is preferably less than 2Mpa.

In the present invention, the flameless oxidation reaction is a conventional reaction in the field. Generally, to realize the flameless oxidation reaction, the fuel and oxygen must meet the following requirements before the contact reaction: the temperature of the reactants or the temperature of the furnace is greater than 800 degrees Celsius, and the oxygen concentration in the furnace is generally Not higher than 15%. The temperature of the flameless oxidation reaction is preferably ≥900°C, more preferably ≥1000°C; the pressure of the flameless oxidation reaction is preferably less than 2Mpa.

Preferably, the synthesis gas is discharged from the gas outlet after heat exchange with the mixed gas containing oxygen, dust removal, desulfurization and purification, and then discharged. The heat exchange, dust removal and desulfurization purification are all conventional operations in the field, and are respectively carried out in the conventional heat exchange device, dust removal device and desulfurization purification device in the field.

Preferably, the mixed gas containing oxygen enters the fixed-bed gasification device after being preheated.

Preferably, said waste treatment method uses the above-mentioned waste treatment system to process waste.

On the basis of conforming to common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain preferred examples of the present invention.

The reagents and raw materials used in the present invention are all commercially available.

The positive progress effect of the present invention is:

1. The present invention realizes the combination of flameless oxidation gasification and graded oxygen supply, and treats organic waste in a fixed-bed gasification device. The above-mentioned completely new fixed-bed gasification device and organic matter treatment method remove the high-temperature oxidation combustion layer that has been difficult to remove in traditional gasification methods and gasifiers, and prevent the conversion of chromium in organic matter into highly toxic hexavalent chromium in the combustion layer , which greatly reduces the degree of waste pollution, and the whole process does not produce tar, which is very suitable for environmentally friendly and efficient treatment of a large amount of complex organic waste.

2. The method of the present invention allows the organic waste to react under a flameless high temperature and a reducing atmosphere, without generating pollutants such as SO ₂ , NO _x and dioxin, and the temperature distribution in the gasifier is uniform, without generating difficult-to-treat tar and phenolic waste water, clean and environmentally friendly. Generally, the gases in the reducing atmosphere are carbon monoxide, hydrogen, methane, nitrogen and carbon dioxide.

3. The specific equipment and process treatment system of the present invention can carry out harmless treatment and resource utilization of organic waste, and there is no need to pre-treat organic waste such as pulping or powder making. The whole system has a wide range of applications and can be operated continuously And large-scale production, the product is clean synthesis gas (the main components are CO and H2, which can be used to produce gas, produce synthetic ammonia, methanol and other chemicals, and generate electricity, etc.), and explore the efficient, environmentally friendly and resourceful utilization of organic waste A new way, with significant economic and environmental benefits, in line with the needs of my country's development of circular economy and ecological industry.

Description of drawings

Fig. 1 is a schematic structural diagram of a fixed bed equipment in a preferred embodiment of the present invention.

Fig. 2 is a schematic process flow diagram of a preferred embodiment of the present invention.

detailed description

The present invention is further illustrated below by means of examples, but the present invention is not limited to the scope of the examples. For the experimental methods that do not specify specific conditions in the following examples, select according to conventional methods and conditions, or according to the product instructions.

Example 1

Behind the rapid development and prosperity of my country's tanning industry, due to the industrial form and processing methods, it has aggravated the pollution of the environment, and many tanning areas show serious heavy metal chromium pollution. Leather scraps are scraps cut from leather, with a calorific value of about 13.7MJ/kg on a dry basis. Taking the scale of processing 100 tons of tanning waste per day as an example, the feed material is leather scrap, and its composition is shown in Table 1. Meaning of symbols: moisture (M), ash (A), volatile matter (V) and fixed carbon (Fc). Received basis (ar): The state of the sample is the state in which the batch of samples was received. Dry base (d): The state of the sample is a state of no moisture. The oxidizing agent is pure oxygen.

Table 1 Composition analysis of leather scraps

As shown in Figures 1 and 2, the fixed-bed gasification device 1 used in this embodiment includes a gasification chamber 10, a waste inlet 11, a solid-liquid outlet 16, a first gas outlet 17, a gas outlet 12, two A second gas inlet 14, a distributor 13, and a grate 15; the waste inlet 11 is arranged on the top of the gasification chamber 10, and communicates with the interior of the gasification chamber 10, and the waste inlet 11 is provided with a distributor 13; solid-liquid The outlet 16 is arranged at the bottom of the gasification chamber 10 and communicates with the inside of the gasification chamber 10; the first gas inlet 17 is arranged at the bottom of the gasification chamber 10 and communicates with the gasification chamber 10, and the second gas inlet 14 is arranged at In the middle of the gasification chamber 10, the ratio of the vertical distance between the second gas inlet 14 and the first gas inlet 17 to the height of the gasification chamber 10 is 0.5; two second gas inlets 14 are symmetrically arranged in the middle of the gasification chamber 10 Both sides; the lower part of the gasification chamber 10 is provided with a grate 15, and is located above the first gas inlet 17; the gas outlet 12 is arranged above the gasification chamber 10 and communicates with the inside of the gasification chamber 10; the gasification chamber 10 The inner wall and fire grate 15 use a water-cooled jacket device (not shown in the figure) to carry out insulation, so as not to be damaged due to excessive temperature.

As shown in Figure 2, the waste system used in this embodiment includes a waste preprocessor 2, two lock buckets 3, the above-mentioned fixed bed gasification device 1, a heat exchanger 4, a dust removal device 5, and a desulfurization purification device 6 , ash hopper 7; waste preprocessor 2, lock hopper 3 and waste inlet 11 are connected sequentially, gas outlet 12 is connected with heat exchanger 4, dust removal equipment 5, desulfurization purification equipment 6 in sequence; ash hopper 7 is connected with solid liquid outlet 16 connections.

After the above-mentioned leather scraps are pretreated by the waste preprocessor, they enter the fixed bed gasification device through the lock hopper and mix with the mixed gas containing oxygen entering the first gas inlet and the second gas inlet, and a flameless oxidation reaction occurs, and the gasification The volume percentage of oxygen in the chamber is kept not more than 15%. The flameless oxidation reaction temperature inside the gasification chamber is 1000°C, the reaction pressure inside the gasification chamber is 0.5Mpa, and the superficial gas velocity in the gasification chamber is less than 1 m/s. The oxygen ratio of the first gas inlet and the second gas inlet is 6:1. The synthesis gas produced in the flameless oxidation reaction is discharged through the gas outlet, and then passes through the heat exchanger to exchange heat with oxygen, then passes through the dust removal device to remove dust, and passes through the desulfurization purification device to obtain the final product synthesis gas. The solid waste produced in the flameless oxidation reaction is discharged through the solid-liquid outlet and enters the ash hopper. The above-mentioned mixed gas containing oxygen is formed by mixing oxygen with one or more of flue gas, steam and carbon dioxide after being preheated by the heat exchanger 4, and the volume percentage of oxygen in the mixed gas does not exceed 15%.

The final product indicators are as follows:

The internal pressure of the fixed-bed gasification device is 0.5MPa, and the oxygen concentration entering the fixed-bed gasifier is controlled at 15%. The outlet synthesis gas temperature is 1000°C, the output of synthesis gas is about 2.1t/h, the content of CO+H ₂ is 43%; the content of Cr ₂ O ₃ is 56%, the ash residue is about 4t/d, and the ash residue containing high concentration of chromium is suitable for the recycling of chromium. Due to the high-temperature flameless gasification, the carbon content in the ash is less than 5%, and no tar is produced in the whole process.

It can be seen that the present invention can carry out harmless treatment and resource utilization of the leather scraps produced in the tanning industry, produce high-quality synthesis gas after gasification, and can gasify the high-chromium content of the material after gasification Ashes are recycled. Through the implementation of the invention, a new approach can be explored for energy saving, environmental protection and resource utilization of tanning waste, which has significant economic and environmental benefits and meets the needs of my country's development of circular economy and ecological industry.

Example 2

Medical waste refers to directly or indirectly infectious, toxic and other hazardous waste produced by medical and health institutions in medical treatment, health care and other related activities. Medical waste contains a large number of germs, viruses and chemicals, and is the medium for the enrichment and transmission of pathogenic microorganisms. It is a typical hazardous waste that can cause great harm to the environment and human body. Taking the daily processing scale of 100 tons of medical waste as an example, its composition is shown in Table 2, and its dry basis calorific value is about 21.9MJ/kg. The oxidant is 50% oxygen enriched.

Table 2 Analysis of components of medical waste

process operating conditions and

The structure of the fixed-bed gasification device used in this example and the structure of the organic waste treatment system are the same as in Example 1, the difference lies in the specific operating parameters. The reaction pressure inside the gasification chamber is 0.2Mpa, the flameless oxidation reaction temperature inside the gasification chamber is 1000°C, and the oxygen ratio of the first gas inlet and the second gas inlet is 4:1.

The product indicators are as follows:

The outlet synthesis gas temperature is 1000°C, the output of synthesis gas is about 5.2t/h, and the content of CO+H ₂ is 59%. Due to the high-temperature flameless gasification, the carbon content in the ash is less than 5%, and no tar is produced in the whole process.

Example 3

In Example 3, the oxygen ratio of the first gas inlet and the second gas inlet is 3:1, the ratio of the vertical distance between the second gas inlet and the first gas inlet to the height of the gasification chamber is 0.4, and the gasification chamber The flameless oxidation reaction temperature inside the body is 900°C, and the rest of the conditions are the same as in Example 1.

The final product indicators are as follows:

The outlet synthesis gas temperature is 900°C, the output of synthesis gas is about 1.9t/h, and the content of CO+H2 is 40%. The carbon content in the ash is less than 5%, and no tar is produced in the whole process.

Example 4

The oxygen ratio of the first gas inlet and the second gas inlet in Example 4 is 10:1. The ratio of the vertical distance between the second gas inlet and the first gas inlet to the height of the gasification chamber is 0.8, and the gasification chamber The internal flameless oxidation reaction temperature is 900° C., and other conditions are the same as in Example 1.

The final product indicators are as follows:

The outlet synthesis gas temperature is 900°C, the output of synthesis gas is about 1.8t/h, and the content of CO+H2 is 38%. The carbon content in the ash is less than 5%, and no tar is produced in the whole process.

It can be seen that the present invention can carry out step-by-step harmless treatment and resource utilization of medical waste, and produce high-quality synthesis gas after gasification. Through the implementation of the invention, a new approach can be explored for the harmless, environment-friendly and resourceful utilization of medical waste, which has significant economic and environmental benefits and meets the needs of my country's development of circular economy and ecological industry.

Claims (8)

1. A waste disposal method, comprising the steps of: Feed the pretreated waste to a fixed-bed gasification device, mix it with a mixed gas containing oxygen, and perform a flameless oxidation reaction to obtain synthesis gas and solid waste; wherein, the mixed gas containing oxygen satisfies the volume of oxygen The percentage does not exceed 15%; the waste mentioned is one or more of tanning scraps, medical absorbent cotton, gauze, masks, latex products, medicines and polypropylene material products; The fixed-bed gasification device includes a gasification chamber, a waste inlet, a solid-liquid outlet, a first gas inlet, a gas outlet, and at least one second gas inlet; the waste inlet is located at the The top of the gasification chamber, and communicated with the inside of the gasification chamber; the solid-liquid outlet is located at the bottom of the gasification chamber and communicated with the inside of the gasification chamber, and the solid-liquid outlet is solid-liquid discharge mouth; the first gas inlet is arranged at the lower part of the gasification chamber and communicates with the gasification chamber, and the second gas inlet is arranged at the middle of the gasification chamber; the second gas inlet is connected with the gasification chamber The vertical distance between the first gas inlets and the height ratio of the gasification chamber is 0.4-0.8; the gas outlet is arranged above the gasification chamber and communicates with the inside of the gasification chamber, and the The gas outlet is a synthesis gas outlet; The ratio of the amount of oxygen in the mixed gas entering the first gas inlet to the total amount of oxygen in the mixed gas entering the second gas inlet is 3:1-10:1. 2. The waste treatment method according to claim 1, characterized in that, when the number of the second gas inlets is more than 2, several of the second gas inlets are equiangularly distributed in the on the same level as the middle of the gasification chamber. 3. The waste treatment method according to claim 1, characterized in that, the vertical distance between the second gas inlet and the first gas inlet, and the height ratio of the gasification chamber are 0.5-0.6. 4. The waste treatment method according to claim 1, characterized in that, the waste inlet is provided with a distributor; And/or, the inner wall of the gasification chamber is provided with a water-cooled jacket device; And/or, a grate is arranged in the lower part of the gasification chamber, and the grate is located above the first gas inlet. 5. The waste treatment method according to claim 1, characterized in that, said treatment method uses a waste treatment system to process waste; The waste treatment system includes a waste preprocessor, at least one lock bucket, a fixed bed gasification device as described in any one of claims 1-4, a heat exchanger, a dust removal device, a Desulfurization and purification device; the waste preprocessor, the lock bucket and the waste inlet are connected in sequence; the gas outlet is connected with the heat exchanger, the dust removal equipment and the desulfurization purification equipment in sequence. 6. The waste treatment method according to claim 5, characterized in that, the waste treatment system further comprises an ash hopper, and the ash hopper is connected to the solid-liquid outlet. 7. The waste treatment method according to claim 1 or 5, wherein the mixed gas containing oxygen is one or more of flue gas, steam and carbon dioxide mixed with oxygen; And/or, the ratio of the amount of oxygen in the mixed gas entering the first gas inlet to the total amount of oxygen in the mixed gas entering the second gas inlet is 4:1-6:1; And/or, the molar ratio of the oxygen atoms in the oxygen to the carbon atoms in the waste is 1:1; And/or, the superficial gas velocity in the gasification chamber is less than 1 m/s; And/or, the reaction temperature inside the gasification chamber is ≥900°C; the working pressure inside the gasification chamber is less than 2Mpa; And/or, the synthesis gas is discharged from the gas outlet after heat exchange with the mixed gas containing oxygen, dust removal, desulfurization and purification, and then discharged. 8. The waste treatment method according to claim 7, characterized in that, the reaction temperature inside the gasification chamber is ≥ 1000°C.