System for co-producing calcium carbide and coal tar by using raw coal and limestone and system for co-producing calcium carbide, LNG (Liquefied Natural Gas) and coal tar

Abstract

The utility model discloses a system for co-producing calcium carbide and coal tar by using raw coal and limestone and a system for co-producing calcium carbide, LNG (Liquefied Natural Gas) and coal tar, which comprises an external heating type rotary kiln unit for producing calcium carbide raw material semi-coke and byproduct coal gas, the external heating type rotary kiln unit is respectively connected with a coal gas purification unit and a semi-coke screening unit, the lime kiln is connected with a lime screening machine, equipment in the semi-coke screening unit and the lime screening machine are respectively connected with a calcium carbide furnace, and the calcium carbide furnace and the coal gas purification unit are respectively connected with a gas holder. The pyrolysis gas, the coal tar and the semi-coke are prepared through pyrolysis of the pulverized coal, the pulverized coal resource is fully utilized, the coal gas with the low calorific value is used as a heat source of the pyrolysis furnace and the lime kiln through coal gasification, the pyrolysis gas with the high calorific value and the calcium carbide furnace gas are synthesized into the LNG with the high value, the calcium carbide production cost is reduced, and a solving thought is provided for optimization and upgrading of calcium carbide production.

Description

Technical Field

[0001] The utility model relates to the field of calcium carbide production, in particular to a system for co-producing calcium carbide and coal tar by utilizing raw coal and limestone, and a system for co-producing calcium carbide, LNG and coal tar. Background Art

[0002] Domestic coal production is mainly concentrated in the central and western regions of Shanxi, Shaanxi, Inner Mongolia, and other regions with rich coal resources. With the improvement of fully mechanized mining and the increase in the proportion of lower-group coal mining, the content of pulverized coal (particle size <6mm) has continued to increase. The long-distance transportation has further increased the proportion of pulverized coal. The combustion process of pulverized coal produces a large amount of dust, which causes great pollution to the environment. The ignition point of pulverized coal is between 300℃ and 500℃, and the lower explosion limit concentration is 34g / m 3 ~47g / m 3 Pulverized coal is prone to explosions under high temperatures or when exposed to open flames, posing significant safety risks to production and storage. Pulverized coal particles are small and can easily clog tiny gaps in equipment, causing it to malfunction and requiring tedious cleaning and repair. Furthermore, pulverized coal entering equipment can cause friction damage to mechanical components, impacting equipment life and reliability. Consequently, the industrial application of pulverized coal is limited, leading to a shortage of lump coal and a significant backlog of pulverized coal. To address this situation, vigorously developing pulverized coal for improved quality and utilization is a key approach to resolving this dilemma.

[0003] First, traditional domestic calcium carbide production processes require significant amounts of electricity, high-quality carbon materials (coke or lignite), and lime. Generally speaking, smaller particle size increases electrical resistance, allowing electrodes to penetrate deeper into the furnace, facilitating furnace operation. In terms of reactivity, smaller particle size increases surface area, resulting in better solid-phase contact and a more favorable reaction. However, if the particle size is too small, gas discharge resistance increases, potentially blocking the furnace gas passages and hindering the reaction. This can also easily lead to aggressive charge blowout and reduce carbon material utilization. Carbon material powder can impair charge permeability, slowing the calcium carbide reaction and spurring charge blowout. Excessive powder can also be carried away by the furnace gases, resulting in inaccurate batching. Furthermore, excessive powder can easily lead to charge collapse during furnace start-up, compromising personnel safety. Therefore, carbon material particle size significantly impacts calcium carbide production. Typically, lignite particle size (15-50mm) is required to be ≥88%, while coke particle size (20-70mm) is required to be ≥90%. Coke or semi-coke, as an important raw material in the calcium carbide industry, is usually made by burning high-quality clean coal lumps, which makes the production cost of calcium carbide high. Therefore, reducing the cost of raw materials is an important measure to reduce the production cost of calcium carbide.

[0004] Secondly, the calcium carbide furnace gas produced in the closed calcium carbide production process mainly contains CO, H2, O2, and CO2, of which CO is the main component accounting for 75%-85%. It is a gas with a high calorific value, with a furnace gas calorific value of 2700-2800kcal / m 3 Calcium carbide furnace gas is generally used to dry semi-coal or as a common fuel for burning lime, resulting in great waste.

[0005] In order to broaden the upstream raw material sources of calcium carbide, make full use of pulverized coal resources, reduce the production cost of calcium carbide, rationally utilize calcium carbide furnace gas, bring better profits to enterprises while solving environmental pollution problems, the present utility model is specially proposed. Utility Model Content

[0006] In response to the problems existing in the prior art, the present invention aims to provide a system for the co-production of calcium carbide and coal tar using raw coal and limestone, as well as a system for the co-production of calcium carbide, LNG, and coal tar. The externally heated rotary kiln process has a wide range of raw material applications, capable of processing raw coal with a particle size of ≤30 mm; a tar yield 10-15% higher than that of the internally heated process; flexible operation, high flexibility, and easy adjustment of process parameters; and high-temperature flue gas recycling and excess exhaust gas waste heat recovery, achieving a heat utilization rate of up to 85%. This system is suitable for pyrolysis of pulverized coal. Based on the composition and structural characteristics of pulverized coal, this system utilizes an externally heated rotary kiln process to pyrolyze it at medium-low temperatures and atmospheric pressure to produce pyrolysis gas, coal tar, and lignite. The pyrolysis gas contains large amounts of CO, H2, and CH4, while the coal tar contains large amounts of aliphatic and aromatic hydrocarbons. The co-production system of pulverized coal pyrolysis gas and calcium carbide furnace gas can be mixed to produce high-value LNG products, and the lignite is used in calcium carbide production.

[0007] To achieve the above purpose, the technical solution of this utility model is as follows:

[0008] In the first aspect, the utility model provides a system for co-producing calcium carbide and coal tar using raw coal and limestone, including an externally heated rotary kiln unit for producing lignite, a raw material for calcium carbide, and by-product coal gas, and a lime kiln for processing limestone into lime, the externally heated rotary kiln unit being respectively connected to a coal gas purification unit and a lignite screening unit, the lime kiln being connected to a lime screening machine, the equipment in the lignite screening unit and the lime screening machine being respectively connected to a calcium carbide furnace, and the calcium carbide furnace and the coal gas purification unit being respectively connected to a gas cabinet.

[0009] Preferably, as a further feasible solution, the externally heated rotary kiln unit includes a drying furnace, an externally heated rotary retorting furnace and a cooling furnace connected in sequence.

[0010] Preferably, as a further feasible solution, the lignite screening unit includes a lignite screening machine, and a mixing molding machine and a briquetting machine connected to the lignite screening machine, and the lignite screening machine, the mixing molding machine and the briquetting machine are all connected to the calcium carbide furnace.

[0011] Preferably, as a further feasible solution, the lime screening machine is connected to the mixing and forming machine, so as to mix the screened lime with the semi-coke and send them to the calcium carbide furnace to produce calcium carbide.

[0012] Preferably, as a further feasible solution, the coal gas purification unit is connected to the cooling furnace, the raw coal gas generated by the externally heated rotary kiln unit is extracted by the coal gas purification unit to obtain coal tar, and the gas holder is connected to the externally heated rotary distillation furnace and the lime kiln through pipelines, respectively, for returning the mixed gas after the coal tar is extracted as fuel gas.

[0013] Secondly, the utility model also provides a system for co-producing calcium carbide, LNG and coal tar using raw coal and limestone, including an LNG device, a coal gasification unit and the above-mentioned system for co-producing calcium carbide and coal tar using raw coal and limestone.

[0014] Preferably, as a further feasible solution, part of the raw coal enters the coal gasification unit, and the coal gasification unit is connected to the lime kiln and the externally heated rotary kiln unit to provide fuel to the lime kiln and the externally heated rotary kiln unit respectively.

[0015] Preferably, as a further feasible solution, the gas holder is connected to the LNG device so as to send the mixed gas in the gas holder to the LNG device to produce LNG.

[0016] The utility model provides a system for the co-production of calcium carbide, LNG, and coal tar using raw coal and limestone. This system uses inexpensive pulverized coal as raw material and produces high-quality lignite via an externally heated rotary kiln unit, while also producing coal tar and high-calorific value coal gas as by-products. After the lignite passes through the lignite screening unit, the lumps are mixed and used directly. The powdered material and lime powder are then mixed and formed into mixed blocks in a mixing and molding machine, making full use of materials of various particle sizes and expanding the range of raw coal options. Clean coal gas can also be mixed with the calcium carbide tail gas generated by the calcium carbide furnace to produce LNG, further improving the economic benefits of the process.

[0017] After screening, the lignite powder with a particle size of less than 3mm and the lime powder with a particle size of less than 5mm are mixed with the block materials after batching and briquetting, and then sent to the calcium carbide furnace to produce calcium carbide and produce calcium carbide tail gas as a by-product; the coal gas passes through the coal gas purification unit to produce clean coal gas and produce coal tar as a by-product. The clean coal gas and the calcium carbide tail gas after dust removal and desulfurization enter the gas tank for mixing, and the mixed gas is sent to the LNG device through the compressor to produce LNG.

[0018] In short, the above system broadens the upstream raw material sources of calcium carbide, fully utilizes pulverized coal resources, reduces the production cost of calcium carbide, and rationally utilizes calcium carbide furnace gas, bringing better profits to the enterprise, while solving the problem of pulverized coal environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0020] Figure 1 This is a schematic diagram of the system structure of Example 1 of the present utility model using raw coal and limestone to co-produce calcium carbide and coal tar;

[0021] Figure 2 This is a schematic diagram of the system structure of Example 2 of the present utility model using raw coal and limestone to co-produce calcium carbide, LNG and coal tar;

[0022] Figure 3 This is a schematic diagram of the system structure for co-producing calcium carbide, LNG and coal tar using raw coal and limestone in Example 3 of the present utility model.

[0023] In the figure, 100 is an externally heated rotary kiln unit; 110 is a drying furnace; 120 is an externally heated rotary retorting furnace; 130 is a cooling furnace; 200 is a lime kiln; 300 is a semi-coke screening unit; 310 is a semi-coke screening machine; 320 is a lime screening machine; 330 is a mixing and forming machine; 340 is a briquetting machine; 400 is a calcium carbide furnace; 500 is a gas purification unit; 510 is a gas cabinet; 600 is a LNG device; 700 is a coal gasification unit. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some of the embodiments of the present invention, not all of them, and are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the directions indicated by the “arrows” and the like in the accompanying drawings are based on the directions shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as a limitation on the present invention.

[0026] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0027] In order to more clearly illustrate the technical solution of the present invention, it is described below in the form of specific embodiments.

[0028] Example 1

[0029] See also Figure 1 The utility model proposes a system for co-producing calcium carbide and coal tar using raw coal and limestone, including an externally heated rotary kiln unit 100 for producing lignite, a raw material for calcium carbide, and by-product coal gas, and a lime kiln 200 for processing limestone into lime. The externally heated rotary kiln unit 100 is respectively connected to a coal gas purification unit 500 and a lignite screening unit 300, and the lime kiln 200 is connected to a lime screening machine 320. The equipment in the lignite screening unit 300 and the lime screening machine 320 are respectively connected to a calcium carbide furnace 400 for feeding lignite and lime as raw materials for calcium carbide into the calcium carbide furnace 400. At the same time, the lime screening machine 320 is connected to a mixing and molding machine 330 in the lignite screening unit 300, so that lime powder with smaller particle size can be mixed and molded with lignite powder and then fed to the calcium carbide furnace 400.

[0030] The calcium carbide furnace 400 and the coal gas purification unit 500 are respectively connected to the gas cabinet 510, which is mainly used to store the calcium carbide furnace gas produced as a by-product in the process of producing calcium carbide in the calcium carbide furnace 400 and the clean coal gas with a higher calorific value obtained by the coal gas purification unit 500, so that the mixed gas can be used as fuel gas in the external heating rotary kiln unit 100 and the lime kiln 200.

[0031] The externally heated rotary kiln unit 100 in the present invention includes a drying furnace 110, an externally heated rotary retorting furnace 120 and a cooling furnace 130 connected in sequence, and adopts a medium-low temperature pyrolysis process to process pulverized coal into calcium carbide raw material semi-coke and by-product raw coal gas, with a dry basis semi-coke yield of 64.55wt%.

[0032] The lignite screening unit 300 includes a lignite screening machine 310, and a mixing molding machine 330 and a briquetting machine 340 connected to the lignite screening machine. The lignite screening machine 310, the mixing molding machine 330 and the briquetting machine 340 are all connected to the calcium carbide furnace 400, and lignite of various particle sizes is fed into the calcium carbide furnace 400 as raw material.

[0033] Specifically, the semi-coke produced by the externally heated rotary kiln unit 100 is fed to the semi-coke screening machine 310 of the semi-coke screening unit 300, where semi-coke powder with a particle size of less than 3 mm accounts for 45% by weight. The raw gas is fed to the gas purification tower of the gas purification unit 500. The lime kiln 200 processes limestone into lime, which is fed to the lime screening machine 320, where lime powder with a particle size of less than 5 mm accounts for 15% by weight.

[0034] After screening by the lignite screening machine 310, the lignite blocks with a particle size ≥3mm are sent to the calcium carbide furnace 400; the lignite powder with a particle size <3mm is sent to the mixing and molding machine 330, pressed into block-shaped mixed blocks by the briquetting machine, and then sent to the calcium carbide furnace 400 through a belt; the remaining lignite powder is sent to the lignite briquetting machine 340, pressed into lignite blocks and sent to the calcium carbide furnace 400; after screening by the lime screening machine 320, the lime blocks with a particle size ≥5mm are sent to the calcium carbide furnace 400.

[0035] The lime screening machine 320 is connected to the mixing and molding machine 330 to mix the screened lime with semi-coke and deliver it to the calcium carbide furnace 400 to produce calcium carbide. Specifically, lime powder with a particle size of less than 5 mm is delivered to the mixing and molding machine 330, where it is mixed with semi-coke powder and then delivered to the calcium carbide furnace 400. Within the calcium carbide furnace 400, the semi-coke and lime react at high temperatures to produce calcium carbide and produce calcium carbide furnace gas. This gas is purified and delivered to the gas cabinet 510. The composition of the calcium carbide furnace gas is shown in Table 1.

[0036] The gas purification unit 500 is connected to the cooling furnace 130 to receive and purify the raw gas after cooling by the externally heated rotary kiln unit 100. The raw gas generated by the externally heated rotary kiln unit 100 is extracted by the gas purification unit 500 to obtain coal tar. The gas holder 510 is connected to the externally heated rotary distillation furnace 120 and the lime kiln 200 through pipelines respectively, and is used to return the clean gas after the extraction of coal tar and the purified calcium carbide furnace gas as fuel gas.

[0037] The coal tar separated by the gas purification unit 500 has a dry basis tar yield of 11.93 wt%. The purified coal gas enters the gas cabinet 510. The composition of the clean coal gas is shown in Table 2.

[0038] Table 1 Calcium carbide furnace gas composition

[0039] composition CO H2 <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[N2]]> <![CDATA[O2]]> coal tar Mol% 80 3 6.5 0 8 1.5 1

[0040] Table 2 Clean gas composition

[0041] composition CO <![CDATA[H2]]> <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[N2]]> <![CDATA[O2]]> <![CDATA[C2H4]]> <![CDATA[C2H6]]> <![CDATA[C3H6]]> <![CDATA[C3H8]]> <![CDATA[C4H 10 ]]> Mol% 7.7 18.2 27.4 29.5 5.6 0.3 2.3 5.0 2.0 1.5 0.5

[0042] Example 2

[0043] See also Figure 2 Based on the basic composition of the system in Example 1, this embodiment provides a system for co-producing calcium carbide, LNG and coal tar using raw coal and limestone, including an LNG device 600, a coal gasification unit 500 and the above-mentioned system for co-producing calcium carbide and coal tar using raw coal and limestone.

[0044] In this system, the gas holder 510 is not connected to the externally heated rotary retort 120 and the lime kiln 200. That is, the clean coal gas and calcium carbide furnace gas are not returned as fuel gas in this system. Instead, the gas holder 510 is connected to the LNG device 600 to send the mixed gas in the gas holder to the LNG device 600 to produce LNG.

[0045] Furthermore, during the conversion stage of the raw coal, part of the raw coal enters the coal gasification unit 700, which is connected to the lime kiln 200 and the externally heated rotary kiln unit 100 to provide fuel to the lime kiln 200 and the externally heated rotary kiln unit 100 respectively.

[0046] Example 3

[0047] See also Figure 3 This embodiment further expands upon Example 2. Specifically, this embodiment also provides a system for co-producing calcium carbide, LNG, and coal tar using raw coal and limestone. Unlike the technical solution in Example 2, the gas holder 510 in the co-production system is not only connected to the LNG unit 600 via pipelines, but is also connected to the externally heated rotary retort 120 and the lime kiln 200 via pipelines.

[0048] Through this setting method, on the one hand, the raw gas supply of the LNG device 600 can be guaranteed, and normal joint production of calcium carbide, LNG and coal tar can be carried out; on the other hand, according to actual operation and production needs, the mixed gas of clean coal gas and calcium carbide furnace gas can be selectively returned to the upstream supply, so that the mixed gas can be used as fuel gas in the externally heated rotary kiln unit 100 and the lime kiln 200.

[0049] The combined production system in this embodiment can selectively adjust the output flow direction of the mixed gas in the gas cabinet 510 to enhance flexibility in specific actual production and meet production needs under different working conditions.

[0050] The system of the utility model which utilizes raw coal and limestone to co-produce calcium carbide, LNG and coal tar realizes the preparation of pyrolysis gas, coal tar and lignite by pyrolysis of pulverized coal, fully utilizes pulverized coal resources, broadens the source of raw materials for calcium carbide production, and utilizes low-calorific-value coal gas from coal gasification to replace high-calorific-value pyrolysis gas and calcium carbide furnace gas as heat sources for pyrolysis furnaces and lime kilns, and synthesizes high-calorific-value pyrolysis gas and calcium carbide furnace gas into high-value LNG, thereby greatly improving the economy of the co-production system, extending the types of products to the upstream and downstream of calcium carbide, reducing the production cost of calcium carbide, and providing a solution for the optimization and upgrading of calcium carbide production enterprises.

[0051] Finally, it should be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will be able to make various modifications and improvements without departing from the principles and essence of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A system for co-producing calcium carbide and coal tar using raw coal and limestone, characterized in that: It includes an externally heated rotary kiln unit for producing lignite as a raw material for calcium carbide and by-product coal gas, and a lime kiln for processing limestone into lime. The externally heated rotary kiln unit is respectively connected to a coal gas purification unit and a lignite screening unit, and the lime kiln is connected to a lime screening machine. The equipment in the lignite screening unit and the lime screening machine are respectively connected to a calcium carbide furnace, and the calcium carbide furnace and the coal gas purification unit are respectively connected to a gas cabinet.

2. The system for co-producing calcium carbide and coal tar using raw coal and limestone as claimed in claim 1, characterized in that: The externally heated rotary kiln unit comprises a drying furnace, an externally heated rotary dry distillation furnace and a cooling furnace which are connected in sequence.

3. The system for co-producing calcium carbide and coal tar using raw coal and limestone as claimed in claim 1, characterized in that: The semi-coke screening unit includes a semi-coke screening machine, and a mixing molding machine and a briquetting machine connected to the semi-coke screening machine. The semi-coke screening machine, the mixing molding machine and the briquetting machine are all connected to the calcium carbide furnace.

4. The system for co-producing calcium carbide and coal tar using raw coal and limestone as claimed in claim 3, characterized in that: The lime screening machine is connected to the mixing and forming machine so as to mix the screened lime with the semi-coke and send the mixture to the calcium carbide furnace to produce calcium carbide.

5. The system for co-producing calcium carbide and coal tar using raw coal and limestone as claimed in claim 2, characterized in that: The gas purification unit is connected to the cooling furnace, and the raw gas generated by the externally heated rotary kiln unit is extracted by the gas purification unit to obtain coal tar. The gas holder is connected to the externally heated rotary distillation furnace and the lime kiln through pipelines, respectively, for returning the mixed gas after extracting the coal tar as fuel gas.

6. A system for co-producing calcium carbide, LNG and coal tar using raw coal and limestone, characterized in that: The invention comprises an LNG device, a coal gasification unit and a system for co-producing calcium carbide and coal tar by utilizing raw coal and limestone as described in any one of claims 1 to 5.

7. The system for co-producing calcium carbide, LNG and coal tar using raw coal and limestone as claimed in claim 6, characterized in that: Part of the raw coal enters the coal gasification unit, and the coal gasification unit is connected to the lime kiln and the externally heated rotary kiln unit for providing fuel to the lime kiln and the externally heated rotary kiln unit respectively.

8. The system for co-producing calcium carbide, LNG and coal tar using raw coal and limestone as claimed in claim 6, characterized in that: The gas holder is connected to the LNG device so as to send the mixed gas in the gas holder to the LNG device to produce LNG.

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