Method for measuring low calorific value of coal

Abstract

The application discloses a testing method for the calorific value of low-calorific-value coal applied to a robot automatic testing device, and the method comprises the following steps: inserting one or more fixed-calorific-value pad papers into a crucible, inserting a low-calorific-value coal sample to be tested into the pad paper, filling oxygen into the crucible in an oxygen bomb, then starting monitoring in a calorimeter, and obtaining the calorific value of the sample; the calorific value of the low-calorific-value coal is lower than 2000 cal / kg, and the bottom of the crucible and the pad paper are not in complete contact. By using the method, automatic, low-cost and rapid measurement of the low-calorific-value coal sample can be realized.

Description

Technical Field

[0001] The invention belongs to the field of electric power, and in particular relates to a method for measuring the calorific value of low calorific value coal by an automated robot. Background Art

[0002] To enhance blending and reduce coal prices for power plants, the incorporation of high-ash (55% to 65% dry basis ash) and low-calorific value (approximately 2000 cal / kg) subsoil coal (hereinafter referred to as "subsoil coal S") is a solution. Comparison of test results for this type of coal with GB / T15224-2010, "Coal Quality Classification," indicates that subsoil coal S is high-ash and low-calorific value.

[0003] However, the conventional method for measuring the calorific value of coal cannot be used to measure the calorific value of coal S by using a robot-automated testing device. Figure 1-3 , it is impossible to measure the accurate calorific value when using the 5E-RILS1800 robot. Figure 1 This is an image of the sample in the crucible after combustion using the device. Figure 2 is the sample distribution in the crucible after testing, Figure 3 The comparison chart of the samples after secondary calcination is shown in Figure 2. Figure 3 It can be seen that the low calorific value coal ash after complete combustion has different colors.

[0004] There are mature methods for testing the calorific value of low calorific value coal. Refer to GB / T213-2008 "Test of the calorific value of coal", which typically include the asbestos wool pad method and the lens paper wrap method.

[0005] The asbestos wool method uses asbestos, which is harmful to the human body. Using asbestos in the laboratory does not meet the requirements of the workplace. Please refer to "Discussion on the Calorific Value Determination Method of Low Calorific Value Sapropel Coal" in the fifth issue of "Coal Quality Technology" in September 2011, which discloses that the asbestos wool pad method cannot ideally determine the calorific value of coal similar to ground coal S.

[0006] The lens paper wrapping method can be used to measure the calorific value of low-calorific value coal, offering the advantages of low material cost and simple operation. However, it cannot perform the delicate and complex paper wrapping process unless equipped with expensive robotic arms and corresponding wrapping components. This makes this method unsuitable for low-cost, rapid calorific value determination using robotic intelligent testing equipment. Manual paper wrapping is a method that requires additional manpower and loses the product's automated experimental operation characteristics, rendering the automated system's anti-cheating capabilities ineffective.

[0007] Chapter 15, Section 6 of the book "Coal Quality Analysis" discloses a method for determining the calorific value of low-calorific coal by adulterating it with highly combustible substances, such as benzoic acid, a standard coal sample, or a recently tested high-calorific coal sample. However, the book does not provide a detailed explanation of the method or the specific steps involved.

[0008] After experimentation, this method has the following problems when used for automated operations:

[0009] (1) When highly combustible materials are added to the upper part of the sample, the highly combustible materials burn on the upper part and cannot have a combustion-supporting effect on the sample.

[0010] (2) When highly flammable substances are added to the lower part of the sample, they are prone to violent combustion in a pure oxygen environment. The jet of flame will cause the sample to splash, thus causing the sample to collapse.

[0011] (3) When mixing a highly combustible substance powder with a sample, the highly combustible substance and the sample should be weighed separately before being fully mixed. This method has good experimental results. However, the mixing process is relatively complicated for both manual and robotic operation. During the operation, the agitator will carry away the sample, resulting in varying degrees of sample loss. This increases the experimental uncertainty and fails to meet the experimental accuracy requirements. In addition, the powder is greatly affected by changes in ambient humidity, which further increases the experimental uncertainty.

[0012] Therefore, the method of doping with highly combustible substances is also not suitable for testing the calorific value of low calorific value coal using robotic automated testing equipment.

[0013] In the prior art, CN202011045263.6 discloses a method for detecting the calorific value of sludge, which solves a technical problem similar to that of the present application. It adopts a method of adding frozen benzoic acid flakes. However, this method is not suitable for rapid calorific value determination of low calorific value coal.

[0014] Here are the reasons:

[0015] (1) When benzoic acid is at the bottom of the sample, it is prone to violent combustion in a pure oxygen environment. The jet of flame will cause the sample to splash, thus causing the sample to collapse.

[0016] (2) Low-temperature frozen benzoic acid flakes will absorb system heat and increase the system error of the calorimeter.

[0017] (3) When benzoic acid flakes are frozen at low temperatures, condensation will occur, causing the sample weight to change and increasing the error of the weighing system.

[0018] (4) The benzoic acid flakes are frozen at low temperatures and condensation occurs. If the temperature is too low for a long time, different degrees of condensation will occur depending on the humidity environment, causing the sample to harden to a certain extent and affecting the experiment. This places high demands on the timeliness of the experiment and seriously affects the resource allocation of the robot system.

[0019] Therefore, a low-cost and rapid measurement method suitable for low calorific value coal is pursued in the art. Summary of the Invention

[0020] One object of the present invention is to provide a method for measuring the calorific value of low calorific value coal, so as to solve the problem that automated testing cannot be achieved during the measurement of low calorific value coal.

[0021] The method for testing the calorific value of low calorific value coal provided by the present invention includes:

[0022] A paper pad is placed in the crucible, and a low calorific value coal sample to be tested is placed on the paper pad. The crucible is filled with oxygen in an oxygen bomb, and then monitoring is started in a calorimeter to obtain the calorific value of the sample;

[0023] The calorific value of the low calorific value coal is lower than 2000 cal / kg, and the bottom of the crucible is not in complete contact with the pad paper.

[0024] In one embodiment of the present invention, the padding paper is provided in the form of a pocket-shaped paper bag.

[0025] In one embodiment of the present invention, the crucible has a curved inner bottom, and after inserting the paper backing, the paper backing does not completely contact the bottom of the crucible. In some embodiments of the present invention, the crucible has a curved bottom. The paper backing burns beneath the coal sample, promoting the complete combustion of the low-calorific value coal sample, while the upper opening does not interfere with sample placement in the automated testing system.

[0026] In one embodiment of the present invention, the sample is tested for burnout after the calorific value test is completed.

[0027] In one embodiment of the present invention, at least 30% of the area of ​​the bottom of the crucible is not in contact with the padding paper via the M-shaped support.

[0028] In one embodiment of the present invention, the bottom of the crucible is supported by a support, which may be a V-shaped support or a cross-shaped support. Achieving the aforementioned non-contact can be achieved by providing a support, such as a cross-shaped support or a V-shaped support, on the bottom of the crucible; or by providing a grid structure or multiple dot-shaped protrusions on the bottom of the crucible.

[0029] In one embodiment of the present invention, the padding paper has a fixed calorific value.

[0030] In one embodiment of the present invention, the padding paper has a fixed calorific value and is plural.

[0031] In one embodiment of the present invention, the testing method specifically includes:

[0032] 1) Place a calorific crucible with a paper pad on the crucible sprocket, and place the coal sample in the weighing hopper via a robotic arm; the weighing hopper is placed on the top of the weighing balance by the robotic arm; and each container is placed on the balance below the weighing hopper in turn;

[0033] 2) The weighing device controls the weighing hopper to make the coal sample fall slowly and evenly onto the padding paper in the container below;

[0034] 3) When the weight of the coal sample reaches the specified range, the weighing hopper stops dropping the sample;

[0035] 4) The weighing device records the weight and places the weighed sample on the sample turntable for standby use;

[0036] 5) The robot grabs the sample and puts it into the oxygen bomb. Under the operation of the robot, the system realizes the oxygen bomb adding water, closing the lid, lifting, oxygenating, laser ignition, testing, degassing, opening the lid, and completing the experiment.

[0037] In one embodiment of the present invention, after the test is completed, the robot automatically discards the discarded crucible to the sample discard port, or dumps the sample inside and places it on a turntable, and uses a camera to photograph the bottom of the crucible to determine whether it is completely burned.

[0038] In one embodiment of the present invention, after the test is completed, the sample in the crucible is identified by identifying the coal ash to determine whether it has been completely burned. This complete combustion is determined manually or automatically by image recognition. During this recognition process, since incompletely burned samples measured using existing methods are distributed at the bottom, it is necessary to ensure that the sample at the bottom of the crucible is processed and identified. In this case, the crucible can be flipped over to release the combustion products, and then the burnt products and the crucible bottom can be automatically identified by image recognition.

[0039] In some embodiments of the present invention, after the test is completed, the presence of collapse in the oxygen bomb is determined manually or by image recognition. In some embodiments of the present invention, after the test is completed, the interior of the oxygen bomb after the experiment is completed is photographed by a camera, and AI is used to identify floating objects in the oxygen bomb to determine whether collapse has occurred.

[0040] The present invention has the following advantages:

[0041] 1) The use of paper padding can isolate the coal sample and realize double-sided combustion of the bottom coal sample, which promotes the burning of the coal;

[0042] 2) The use of a curved crucible can achieve complete combustion of low calorific value coal samples in the crucible;

[0043] 3) The lower limit of coal sample calorific value detection is improved, and Qb,ab≥8000J / g can be achieved using the paper pad method. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 , photos of coal ash from unburned low calorific value coal samples;

[0045] Figure 2 , a photo of the interior of the crucible after the unburned low calorific value coal ash was taken out;

[0046] Figure 3 , a comparison of the ash photos of the unburned low calorific value coal sample and the ash photos in the burnt crucible;

[0047] Figure 4 , Photos showing collapse during testing in some embodiments. DETAILED DESCRIPTION

[0048] The following are specific examples of the present invention, which are only used to explain the present invention and are not intended to limit the present invention.

[0049] In the following embodiment, the 5E-RILS800 robot intelligent testing equipment of Changsha Kaiyuan Instrument Equipment Co., Ltd. was selected to test the calorific value of low calorific value coal. Intelligent testing equipment with similar structure and testing process can be selected to perform the following coal calorific value measurement operation.

[0050] As mentioned above, there is a lack of fast and effective automatic testing methods for low calorific value coal in this field. Figure 1 As shown in Table 1, the calorific value of coal determined by direct method can be seen in the coal ash with obvious black powder inside, which is the unburned coal sample, and obvious black traces can be seen inside the crucible ( Figure 2 ), which is the coal sample adhering to the inside of the crucible. Figure 1 The powder obtained was further burned in a muffle furnace at 815°C, and the color of the obtained coal ash turned to grayish white ( Figure 3 ), and the large error value of the direct method shows that the use of robotic intelligent testing equipment cannot achieve the calorific value test of low calorific value coal.

[0051] Table 1. Comparison of the calorific value of coal measured by direct method and mirror paper method

[0052]

[0053]

[0054] To this end, the present invention first provides a method for measuring the calorific value of low calorific value coal, which is as follows:

[0055] A padding paper is placed in the crucible, and a low calorific value coal sample to be tested is placed on the padding paper. The crucible is filled with oxygen in an oxygen bomb, and then the test is started in the calorimeter to obtain the calorific value of the sample.

[0056] In one embodiment of the present invention, a parallel testing method is adopted for the low calorific value coal sample, and when the parallel samples are out of tolerance, they are regarded as invalid data.

[0057] In one embodiment of the present invention, the crucible has a curved inner bottom. After inserting the paper backing, the backing does not completely contact the bottom of the crucible. A typical curved crucible is a pear-shaped crucible, which has a larger curvature than ordinary crucibles. The paper backing burns beneath the coal sample, promoting the complete burnout of the low-calorific value coal sample. The upper opening does not interfere with sample placement in the automated testing system.

[0058] In the process of improving the technical solution, the inventors improved the test method and the test device to obtain more accurate measurement values.

[0059] The following table shows the calorific value of coal obtained using a pear-shaped crucible test.

[0060] Table 2. Comparison of coal calorific value measured by the pear-shaped crucible direct method and the mirror paper method

[0061] Experiment number Pear-shaped crucible direct method (J / g) Lens paper method (J / g) Error (J / g) 11 13473 13489 -16 12 13461 13474 -13 13 12677 12687 -10 14 12694 12667 27 15 11267 11244 23 16 11241 11307 -66 17 10592 10657 -65 18 10602 10741 -139 19 9514 9841 -327 20 9611 9852 -241

[0062] As can be seen from the table above, the pear-shaped crucible method provides superior measurement results in the low calorific value range compared to ordinary crucibles. Taking 9852 J / g coal as an example, the measurement error is reduced by 52.7% compared to the ordinary crucible method. This shows that the use of a pear-shaped crucible can greatly reduce the measurement error and make the lower limit of the calorific value of low calorific value coal that can be measured reach Qb,ad ≥ 11000 J / g.

[0063] The error in the measurement process was improved by using a pear-shaped crucible, but the above-mentioned error still did not meet expectations to a certain extent. The inventors then experimented with the bottoms of crucibles of other shapes, specifically including setting a grid structure, a cross structure, a crisscross structure, and a raised structure on the bottom of the crucible. Although these structures were improved compared to the pear-shaped crucible, the error still did not meet expectations.

[0064] The inventors discovered that the use of a paper backing method further increases the lower limit of the measurable calorific value of low-calorific coal, as detailed in the table below. Using a paper backing equivalent to a fixed calorific value of 20 J / sheet, the coal sample can be isolated from the bottom and burned on both sides.

[0065] In some embodiments of the present invention, the padding paper is provided in the form of a paper pocket in a pocket.

[0066] Table 3. Comparison of coal calorific value measured by the pear-shaped crucible direct method and the mirror paper method

[0067] Paper pad + pear-shaped crucible method (J / g) Lens paper method (J / g) Error (J / g) 1 13487 13489 -2 2 13477 13474 3 3 12694 12687 7 4 12627 12667 -40 5 11215 11244 -29 6 11384 11307 77 7 10620 10657 -37 8 10791 10741 50 9 9881 9841 40 10 9906 9852 54 11 9214 9269 -55 12 9108 9037 71

[0068] As can be seen from Table 3, the above method significantly reduces the error. When the calorific value of the coal is as low as 9037 J / g, the error range can still be guaranteed to be within 0.785%.

[0069] In one embodiment of the present invention, the padding paper has a known fixed calorific value (weight 64 mg, calorific value 120 ± 10 J, and the calorific value can be further simply controlled by controlling the area). Increasing the number of padding papers can be used to increase the lower limit of the measurement value. For coal with low calorific value, the measurement accuracy can be further improved by increasing the number of padding papers. The calorific value of the padding paper can be adjusted as needed, and only the corresponding calorific value needs to be deducted after the actual result is measured. By improving the padding paper and crucible, the calorific value measurement of low calorific value coal of 8000 J / g can be achieved.

[0070] In one embodiment of the present invention, after the calorific value test is completed, the sample is tested for burnout. Although the automatic testing device can perform parallel testing and determine whether the test is valid through parallel testing, when testing low-calorific value coal, due to its low calorific value, parallel samples of unburned coal will be considered valid data because they do not exceed the tolerance. Therefore, to ensure the validity of the results, the coal ash can be tested after the test to determine whether there is any unburned coal.

[0071] In some embodiments of the present invention, the use of pocket-shaped paper bags can avoid incomplete combustion compared to the method of using a simple paper sheet. After using a pocket with a fixed calorific value to fill the paper bag, the corresponding procedure for detecting coal ash can be saved.

[0072] In another case, low-calorific value coal may cause a collapse in the oxygen bomb due to combustion. This can be identified manually or through image recognition. During image recognition, the robotic intelligent inspection system can take pictures of the interior of the oxygen bomb and automatically identify the collapse through AI to identify floating objects.

[0073] The present invention further provides a method for automatically testing low calorific value coal, comprising:

[0074] 1) Place a calorific crucible with a paper pad on the crucible sprocket, and place the coal sample in the weighing hopper via a robotic arm; the weighing hopper is placed on the top of the weighing balance by the robotic arm; and each container is placed on the balance below the weighing hopper in turn;

[0075] 2) The weighing device controls the weighing hopper to make the coal sample fall slowly and evenly onto the padding paper in the container below;

[0076] 3) When the weight of the coal sample reaches the specified range, the weighing hopper stops dropping the sample;

[0077] 4) The weighing device records the weight and places the weighed sample on the sample turntable for standby use;

[0078] 5) The robot grabs the sample and puts it into the oxygen bomb. Under the operation of the robot, the system realizes the oxygen bomb adding water, closing the lid, lifting, oxygenating, laser ignition, testing, degassing, opening the lid, and completing the experiment.

[0079] In one embodiment of the present invention, after the test is completed, a robot automatically discards the discarded crucible into a sample disposal port or dumps the sample contents onto a turntable. A camera then images the crucible's bottom to determine complete combustion. In some cases, if a secondary test is required, the discarded crucible can be stored; otherwise, the sample can be discarded.

[0080] After the test is complete, complete combustion should be checked. This is achieved through manual or automatic image recognition. During this process, since incompletely burned samples measured using existing methods are distributed at the bottom, it is necessary to ensure that the sample at the bottom of the crucible is processed and identified. In one embodiment, after the test is completed, the sample in the crucible is identified by identifying the coal ash to determine whether it has been completely burned. This process can be accomplished through manual or image recognition.

[0081] The method of the present invention can further reduce the probability of sample collapse compared to other methods, but sample collapse is still inevitable. In some embodiments, after the test is completed, the presence of sample collapse in the oxygen bomb is determined manually or by image recognition. When performing image recognition, the robot intelligent inspection system takes a picture of the inside of the oxygen bomb and automatically identifies the sample collapse through AI recognition of floating objects, such as Figure 4 As shown, the collapse pattern is identified by tracking the background.

[0082] In some embodiments of the present invention, the use of pocket-shaped paper bags can further reduce or avoid crumbling compared to the method of using a simple paper sheet.

[0083] Compared with existing methods, the method of the present invention can reduce the cost of testing, the required steps are simple and can be standardized, and can be used for rapid testing.

[0084] The test method provided by the present invention is described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core ideas of the present invention. It should be noted that, for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for testing the calorific value of low calorific value coal, comprising: 1) One or more pieces of fixed calorific value paper are placed in the crucible, and the crucible with the calorific value paper is placed on the crucible sprocket. The coal sample is placed in the weighing hopper by the robot arm; the weighing hopper is placed on the top of the weighing balance by the robot arm; and each container is placed on the balance below the weighing hopper in turn; 2) The weighing device controls the weighing hopper to make the coal sample fall onto the padding paper in the container below; 3) When the weight of the coal sample reaches the specified range, the weighing hopper stops dropping the sample; 4) The weighing device records the weight and places the weighed sample on the sample turntable for standby use; 5) The robot grabs the sample and puts it into the oxygen bomb. Under the operation of the robot, the system realizes the oxygen bomb adding water, closing the lid, lifting, oxygenating, igniting, testing, degassing, opening the lid, and completing the experiment to obtain the calorific value of the sample; The calorific value of the low calorific value coal is lower than 2000 cal / kg, and the bottom of the crucible is not in complete contact with the paper pad; The crucible has an inner wall with a curved bottom, and after the pad paper is placed in, the pad paper is not in complete contact with the bottom of the crucible.

2. The testing method according to claim 1, wherein: After the calorific value test is completed, the sample is tested for burnout.

3. The testing method according to claim 1, wherein: At least 30% of the surface area of ​​the paper pad is not in contact with the bottom of the crucible.

4. The testing method according to claim 1, wherein: The padding paper is plural.

5. The testing method according to claim 1, wherein: After the test is completed, the robot will discard the discarded crucible into the sample disposal port, or pour out the sample inside and place it on the turntable, and use the camera to take a picture of the bottom of the crucible to determine whether it is completely burned.

6. The testing method according to claim 1, wherein: After the test is completed, the sample in the crucible is judged to be completely burned by identifying the coal ash.

7. The testing method according to claim 1, wherein: By manually or through camera images, AI can be used to identify floating objects on the water surface to determine whether there are collapsed objects in the oxygen bomb.

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