A system and method for preparing clean coal by self-drying coal slime or low-rank coal

Abstract

The present invention discloses a system and method for preparing clean coal by self-drying coal slime or low-rank coal, including a coal slime / low-rank pulverized coal briquetting device, a track for running shaped coal blocks, a heating chamber, a retorting chamber, a cooling chamber, a clean coal kiln transfer chamber, a combustion chamber, a flue gas duct, a pump, an exhaust gas treatment device, and an exhaust gas reuse pipeline. The system controls the air pressure and exhaust gas recycling speed in the system through a pump and an electrically controlled regulating valve. A gas mixing chamber is arranged outside the retorting chamber in the system, and the combustible gas concentration and oxygen concentration in the coal gas are controlled by an electrically controlled fan. A gas outlet pipe is arranged inside the retorting chamber, and a temperature sensor is arranged on the top of the gas outlet pipe to monitor the temperature of the retorting chamber. The coal slime or low-rank coal treated by the system has lower volatile matter and sulfur content, and can be directly used for civilian combustion.

Description

Technical Field

[0001] The present invention relates to a clean coal preparation technology, and in particular to a system and method for preparing clean coal by self-drying coal slime or low-rank coal. Background Art

[0002] In the current energy structure, oil and natural gas resources are scarce, while coal reserves are relatively abundant, accounting for nearly 70% of the energy structure, and occupying a dominant position, and more than 55% is low-rank coal with a low degree of coalification. However, due to the high water content of low-rank coal, the direct combustion or gasification efficiency is low, and the existing technology cannot fully utilize its resource value, resulting in a huge waste of coal resources. At the same time, a large amount of water-containing semi-solid matter, namely coal slime, is produced during the coal washing process. It has a high ash content and low calorific value and is a waste in the coal production process. Due to factors such as ash content, water content, and sulfur content, the utilization of low-rank coal and coal slime is greatly restricted.

[0003] In the existing technology, efficient pyrolysis is often used as a guide to extract the existing oil and gas resources in coal, and the remaining semi-coke is burned to generate electricity or converted into fuel and chemicals after gasification. The process is complicated and the conditions for obtaining the product are relatively harsh. Therefore, it is necessary to provide a method for directly using coal slime or low-rank coal to make clean coal to solve the above technical problems. Summary of the invention

[0004] The object of the present invention is to provide a system and method for preparing clean coal by self-drying coal slime or low-rank coal.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] The system for preparing clean coal by self-drying coal slime or low-rank coal of the present invention comprises a coal slime / low-rank pulverized coal briquetting device and a shaped coal block running track, wherein a heating chamber, a retorting chamber, a cooling chamber, and a clean coal kiln transfer chamber are sequentially arranged on the shaped coal block running track along the flow direction of the shaped coal blocks, wherein the heating chamber, the retorting chamber, and the cooling chamber are fixed by a fireproof wall, and a combustion chamber is arranged inside the heating chamber and the retorting chamber, and one-way doors are respectively arranged at both ends of the clean coal kiln transfer chamber;

[0007] A flue gas duct is arranged at the front end of the heating chamber, and the flue gas outlet after combustion in the combustion chamber is connected to the tail gas treatment device and the tail gas reuse pipeline respectively through a pump and the flue gas duct;

[0008] An electrically controlled regulating valve is provided at the front end of the flue gas inlet of the exhaust gas treatment device;

[0009] The outlet of the tail gas reuse pipeline is respectively connected to the end of the cooling chamber and the clean coal kiln transfer chamber.

[0010] The above-mentioned system for preparing clean coal by self-drying coal slime or low-rank coal realizes a method for preparing clean coal by self-drying coal slime or low-rank coal, comprising the steps of:

[0011] The shaped coal blocks flow through the heating chamber, the retorting chamber, the cooling chamber, and the clean coal kiln transfer chamber in sequence on the running track, and are heated by the combustion chamber inside the heating chamber and the retorting chamber;

[0012] The flue gas after combustion in the combustion chamber is extracted by a pump and enters the exhaust gas treatment device and the exhaust gas reuse pipeline through the flue gas duct arranged at the front end of the heating chamber; the exhaust gas volume entering the exhaust gas treatment device and the exhaust gas reuse pipeline is controlled by the electric control regulating valve arranged at the front end of the exhaust gas treatment device;

[0013] The tail gas of the tail gas reuse pipeline enters the end of the cooling chamber and the clean coal kiln transfer chamber respectively;

[0014] There is no direct gas exchange between the gas in the inner cavity of the combustion chamber and the heating chamber, the dry distillation chamber and the cooling chamber.

[0015] It can be seen from the technical solution provided by the present invention as described above that the system and method for preparing clean coal by self-drying coal slime or low-rank coal provided in the embodiment of the present invention do not require an external heat source, while reducing the loss of thermal energy, and realizing a one-step method for preparing clean coal from coal slime or low-rank coal. The system has the characteristics of simple operation and high safety factor, and the obtained product can be directly used for civilian combustion, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a system for preparing clean coal by self-drying coal slime or low-rank coal provided in an embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of the structure of the heating chamber in an embodiment of the present invention.

[0018] Figure 3 Schematic diagram of the structure of the distillation chamber in an embodiment of the present invention.

[0019] In the figure:

[0020] 1- coal slime / low-grade pulverized coal briquetting device; 2- track for running shaped coal blocks; 3- heating chamber; 4- dry distillation chamber; 5- cooling chamber; 6- transfer chamber for clean coal out of kiln; 7- fireproof wall; 8- combustion chamber; 9- one-way door; 10- flue gas duct; 11- pump; 12- electric control valve; 13- tail gas treatment device; 14- tail gas reuse pipeline;

[0021] 401-gas transmission pipeline; 402-gas mixing chamber; 403-electrically controlled fan; 404-mixed gas output pipe; 405-gas sensor; 406-burner; 407-gas outlet pipe; 408-temperature sensor management device. DETAILED DESCRIPTION

[0022] The embodiments of the present invention will be described in further detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0023] The system and method for preparing clean coal by self-drying coal slime or low-rank coal of the present invention, the preferred specific implementation manner is:

[0024] The system for preparing clean coal by self-drying coal slime or low-rank coal includes a coal slime / low-rank pulverized coal briquetting device and a shaped coal block running track. A heating chamber, a retorting chamber, a cooling chamber, and a clean coal kiln transfer chamber are sequentially arranged on the shaped coal block running track along the flow direction of the shaped coal blocks. The heating chamber, the retorting chamber, and the cooling chamber are fixed by a refractory wall, and a combustion chamber is arranged inside the heating chamber and the retorting chamber. One-way doors are respectively arranged at both ends of the clean coal kiln transfer chamber;

[0025] A flue gas duct is arranged at the front end of the heating chamber, and the flue gas outlet after combustion in the combustion chamber is connected to the tail gas treatment device and the tail gas reuse pipeline respectively through a pump and the flue gas duct;

[0026] An electrically controlled regulating valve is provided at the front end of the flue gas inlet of the tail gas treatment device;

[0027] The outlet of the tail gas reuse pipeline is respectively connected to the end of the cooling chamber and the clean coal kiln transfer chamber.

[0028] The top of the combustion chamber is made of refractory brick material, the bottom is made of heat storage ceramic material, and the inner cavity of the combustion chamber is isolated from the heating chamber, the retorting chamber and the cooling chamber.

[0029] A gas delivery pipeline is arranged in the middle of the carbonization chamber, the outlet of the gas delivery pipeline is connected to the gas mixing chamber, and the gas mixing chamber is connected to the combustion chamber via a mixed gas output pipe;

[0030] The gas mixing chamber is provided with an electric-controlled fan, the mixed gas output pipe is provided with a gas sensor, the retorting chamber is provided with a gas outlet pipe, the top of the gas outlet pipe is provided with a temperature sensor, and the top of the combustion chamber is provided with a burner.

[0031] The above-mentioned system for preparing clean coal by self-drying coal slime or low-rank coal realizes a method for preparing clean coal by self-drying coal slime or low-rank coal, comprising the steps of:

[0032] The shaped coal blocks flow through the heating chamber, the retorting chamber, the cooling chamber, and the clean coal kiln transfer chamber in sequence on the running track, and are heated by the combustion chamber inside the heating chamber and the retorting chamber;

[0033] The flue gas after combustion in the combustion chamber is extracted by a pump and enters the exhaust gas treatment device and the exhaust gas reuse pipeline through the flue gas duct arranged at the front end of the heating chamber; the exhaust gas volume entering the exhaust gas treatment device and the exhaust gas reuse pipeline is controlled by the electric control regulating valve arranged at the front end of the exhaust gas treatment device;

[0034] The tail gas of the tail gas reuse pipeline enters the end of the cooling chamber and the clean coal kiln transfer chamber respectively;

[0035] There is no direct gas exchange between the gas in the inner cavity of the combustion chamber and the heating chamber, the dry distillation chamber and the cooling chamber.

[0036] The gas generated by coal dry distillation in the dry distillation chamber enters the gas mixing chamber through the coal gas delivery pipeline and is mixed by the electric-controlled fan;

[0037] The mixed gas enters the combustion chamber through the mixed gas output pipe; the gas sensor arranged on the mixed gas output pipe is used to monitor the methane concentration, hydrogen concentration, carbon monoxide concentration and oxygen concentration.

[0038] According to the explosion limit formula L=1 / (Y1 / L1+Y2 / L2+Y3 / L3), the comprehensive explosion lower limit of the mixed combustible gas is calculated, and the concentration of each combustible gas in the mixing chamber is controlled by controlling the electric control fan, so that the mixed gas is far away from the explosion lower limit, and the oxygen amount can only maintain the full combustion of each combustible gas without excess oxygen, and the data is continuously monitored by the gas sensor and programmed and controlled by the programmable controller;

[0039] In the above formula: Y1, Y2, Y3 represent the different combustible gas compositions in the mixture, L1, L2, L3 represent the corresponding explosion limits of each component of the mixed gas.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] This method does not require external heat source, reduces heat energy loss, and realizes the one-step preparation of clean coal from coal slime or low-rank coal. It has the characteristics of simple operation and high safety factor, and the obtained product can be directly used for civilian combustion, etc. Specific embodiment:

[0043] Attached Figure 1 A schematic diagram of the structure of a system for preparing clean coal by self-drying coal slime or low-rank coal according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the heating chamber in the embodiment of the present invention. Figure 3 Schematic diagram of the structure of the distillation chamber in an embodiment of the present invention.

[0044] As attached Figure 1 , 2As shown in Figure 3, refractory bricks are used for the refractory wall and the top of the combustion chamber, honeycomb heat storage ceramics are used for the bottom of the combustion chamber, and heat-insulating and high-temperature resistant materials are used for the mixing chamber, the mixed gas output pipe and the gas outlet pipe. The burner is located at the top of the combustion chamber, and propane is used as the starting fuel of the burner to heat the combustion chamber. The coal mud or low-grade pulverized coal is made into a honeycomb briquette shape through the briquetting device, and enters the heating chamber through the running track of the shaped coal block. The residence time in the heating chamber is 1 hour. When the shaped coal block enters the dry distillation chamber through the running track after heating, the propane input is stopped when the temperature sensor shows that the temperature exceeds 950 degrees. The shaped coal block stays in the dry distillation chamber for 1 hour, and then leaves the dry distillation chamber and enters the cooling chamber. The temperature in the dry distillation chamber is controlled by the power of the pump and the electric control fan connected to the gas mixing chamber. The gas inlet for the raw coal gas to enter the mixing chamber is set at the interface between the dry distillation chamber and the cooling chamber, so that the highest temperature section gas of the dry distillation chamber and the cooling section can be taken out, forming a gas flow from both ends of the kiln to the gas inlet. The shaped coal blocks release a large amount of raw coal gas through high-temperature dry distillation in the dry distillation chamber. Due to the high temperature, the air pressure in this area is greater than the atmospheric pressure, causing the raw coal gas to enter the gas mixing chamber through the gas delivery pipeline. The air intake speed of the electric-controlled fan is regulated according to the methane, hydrogen and carbon monoxide concentrations of the gas sensor and the temperature of the temperature sensor, so that the gas in the combustion chamber is within the safe combustion concentration range and the temperature of the dry distillation chamber is maintained at 950 degrees. The pump draws the exhaust gas after combustion in the combustion chamber above the dry distillation chamber into the combustion chamber above the heating chamber and further into the flue gas pipeline. The exhaust gas volume entering the exhaust gas treatment device and the exhaust gas reuse pipeline is controlled by the electric-controlled regulating valve arranged at the front end of the exhaust gas treatment device. The exhaust gas reuse pipeline is respectively connected to the end of the cooling chamber and the clean coal kiln transfer chamber. The exhaust gas reuse system controls the oxygen concentration in the heating chamber and the dry distillation chamber to be close to 0. The shaped coal blocks enter the cooling chamber, are cooled by the cooled reused tail gas, enter the clean coal kiln transfer chamber through the one-way door and are moved out. Due to the tail gas reuse system, the air pressure inside the clean coal kiln transfer chamber is higher than the atmospheric pressure, and it is ensured that there is no oxygen interference in the heating chamber, distillation chamber and cooling chamber.

[0045] According to the explosion limit formula L = 1 / (Y1 / L1+Y2 / L2+Y3 / L3) (where Y1, Y2, and Y3 represent the different flammable gas compositions in the mixture, and L1, L2, and L3 represent the corresponding explosion limits of each component of the mixed gas), the comprehensive explosion limit of the mixed combustible gas is calculated, and the concentration of each flammable gas in the mixing chamber is controlled by controlling the electric control fan, so that the mixed gas is far away from the explosion limit, and the oxygen amount can only maintain the full combustion of each flammable gas without excess oxygen. The data is continuously monitored by the sensor and controlled by the programmable controller.

[0046] The gas pressure difference on both sides of the coal block inlet damper should always be kept at zero to prevent outside air from entering and gas from overflowing from the kiln. The zero pressure difference is controlled by the exhaust gas reuse volume, which is controlled by the pump and the electric control valve. The pump air volume is controlled by the frequency converter, which is controlled by the online monitoring data of the zero pressure difference sensor through the programmable controller program.

[0047] The product obtained by this method can be directly used for civil combustion, etc.

[0048] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing clean coal by self-drying coal slime or low-rank coal, which is achieved by a system for preparing clean coal by self-drying coal slime or low-rank coal, and is characterized by: The system for preparing clean coal by self-drying coal slime or low-rank coal comprises a coal slime / low-rank pulverized coal briquetting device and a shaped coal block running track. A heating chamber (3), a retorting chamber (4), a cooling chamber (5), and a clean coal kiln transfer chamber (6) are sequentially arranged on the shaped coal block running track (2) along the flow direction of the shaped coal blocks. The heating chamber (3), the retorting chamber (4), and the cooling chamber (5) are fixed by a fireproof wall (7). A combustion chamber (8) is arranged inside the heating chamber (3) and the retorting chamber (4). One-way doors (9) are respectively arranged at both ends of the clean coal kiln transfer chamber (6). A flue gas duct (10) is provided at the front end of the heating chamber (3); a flue gas outlet after combustion in the combustion chamber (8) is connected to an exhaust gas treatment device (13) and an exhaust gas reuse pipeline (14) respectively via a pump (11) and the flue gas duct (10); An electric control regulating valve (12) is provided at the front end of the flue gas inlet of the exhaust gas treatment device (13); The outlet of the tail gas reuse pipeline (14) is respectively connected to the end of the cooling chamber (5) and the clean coal kiln transfer chamber (6); The method for preparing clean coal by self-drying coal slime or low-rank coal comprises the following steps: The shaped coal blocks flow through the heating chamber (3), the retorting chamber (4), the cooling chamber (5), and the clean coal kiln transfer chamber (6) in sequence on the running track (2), and are heated in the combustion chamber (8) inside the heating chamber (3) and the retorting chamber (4); The flue gas after combustion in the combustion chamber (8) is extracted by a pump (11) and enters an exhaust gas treatment device (13) and an exhaust gas reuse pipe (14) through a flue gas duct (10) arranged at the front end of the heating chamber (3); the exhaust gas volume entering the exhaust gas treatment device (13) and the exhaust gas reuse pipe (14) is controlled by an electric control regulating valve (12) arranged at the front end of the exhaust gas treatment device (13); The tail gas from the tail gas reuse pipeline (14) enters the end of the cooling chamber (5) and the clean coal kiln transfer chamber (6) respectively; There is no direct gas exchange between the gas in the inner cavity of the combustion chamber (8) and the heating chamber (3), the dry distillation chamber (4) and the cooling chamber (5).

2. The method for preparing clean coal by self-drying coal slime or low-rank coal according to claim 1, characterized in that: The top of the combustion chamber (8) is made of refractory brick material, and the bottom is made of heat storage ceramic material. The inner cavity of the combustion chamber (8) is isolated from the heating chamber (3), the retorting chamber (4) and the cooling chamber (5).

3. The method for preparing clean coal by self-drying coal slime or low-rank coal according to claim 2, characterized in that: A gas delivery pipeline (401) is arranged in the middle of the dry distillation chamber (4), the outlet of the gas delivery pipeline (401) is connected to a gas mixing chamber (402), and the gas mixing chamber (402) is connected to the combustion chamber (8) via a mixed gas output pipe (404).

4. The method for preparing clean coal by self-drying coal slime or low-rank coal according to claim 3, characterized in that: The gas mixing chamber (402) is provided with an electric-controlled fan (403), the mixed gas output pipe (404) is provided with a gas sensor (405), a gas outlet pipe (407) is provided in the retorting chamber (4), a temperature sensor (408) is provided at the top of the gas outlet pipe (407), and a burner (406) is provided at the top of the combustion chamber.

5. The method for preparing clean coal by self-drying coal slime or low-rank coal according to claim 4, characterized in that: The gas generated by coal dry distillation in the dry distillation chamber (4) enters the gas mixing chamber (402) through the coal gas delivery pipeline (401) and is mixed by the electric-controlled fan (403); The mixed gas enters the combustion chamber (8) via the mixed gas output pipe (404); the gas sensor (405) provided on the mixed gas output pipe (404) is used to monitor the methane concentration, hydrogen concentration, carbon monoxide concentration and oxygen concentration.

6. The method for preparing clean coal by self-drying coal slime or low-rank coal according to claim 5, characterized in that: According to the explosion limit formula L=1 / (Y1 / L1+Y2 / L2+Y3 / L3), the comprehensive explosion lower limit of the mixed combustible gas is calculated, and the concentration of each combustible gas in the mixing chamber is controlled by controlling the electric control fan (403), so that the mixed gas is far away from the explosion lower limit, and the amount of oxygen is only enough to maintain the full combustion of each combustible gas without excess oxygen, and the data is continuously monitored by the gas sensor (405) and controlled by the programmable controller; In the above formula: Y1, Y2, Y3 represent the different combustible gas compositions in the mixture, L1, L2, L3 represent the corresponding explosion limits of each component of the mixed gas.

Images