Application of a method for evaluating the efficiency of waste heat recovery from raw gas in coke oven riser

Abstract

The present invention proposes an application method for evaluating the efficiency of waste heat recovery of raw coal gas in a coke oven riser. First, data monitoring is performed on the existing waste heat recovery of raw coal gas in the coke oven riser. Then, the waste heat recovery system of the raw coal gas in the riser is calibrated to obtain the waste heat recovery rate of the raw coal gas, thereby determining the amount of raw coal gas, the heat capacity of the raw coal gas and the temperature of the raw coal gas, and obtaining the amount of raw coal gas generated, the heat brought out by the raw coal gas, and the sensible heat and latent heat of the raw coal gas; then, the water vapor production and yield are determined through the material balance of the waste heat recovery system of the raw coal gas in the riser; finally, the heat recovered by the system, the recovery rate of the waste heat of the raw coal gas, and the recovery rate of the sensible heat of the raw coal gas are determined through the heat balance of the waste heat recovery system of the raw coal gas in the riser, and the amount of circulating ammonia water sprayed is reduced based on the recovery rate, while reducing the amount of cooling water used in the horizontal tube primary cooler after the waste heat recovery device of the raw coal gas in the coke oven riser is used, and based on this, the energy-saving effect and emission reduction effect of the system are evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of waste energy recovery, and in particular to a method for evaluating the waste heat recovery efficiency of raw gas in a coke oven riser and its application in reducing the amount of circulating ammonia water and reducing the amount of cooling water used in a coke oven gas purification system. Background Art

[0002] The raw gas produced during the coal distillation process in the coking process will pass through the top of the carbonization chamber 1, the riser 2, the bridge pipe 3, and then enter the gas collecting pipe ( Figure 1 ). The coking temperature in the coke oven is as high as over 1050°C, and the temperature of the high-temperature raw gas produced is 700-800°C. In the prior art, the raw gas is mainly cooled by spraying ammonia water before it is introduced into the gas collecting pipe. Circulating ammonia water is used for spraying and cooling at the bridge pipe and the gas collecting pipe to cool the raw gas originally at about 700°C to about 84°C. After that, the raw gas will be sucked into the cold drum section through the suction elbow and the suction pipe. An ammonia water nozzle is provided at the turning point of the bridge pipe to spray hot ammonia water and cool the raw gas by evaporation of ammonia water. A water seal cover is provided on the upper part of the bridge pipe to prevent the raw gas from escaping and polluting the atmosphere, and an ammonia water nozzle 4 or a high-pressure ammonia water nozzle 5 is also provided at the turning point of the bridge pipe. The ammonia water with increased temperature is cooled by natural cooling or heat exchange.

[0003] In the prior art CN116179222A, a waste heat recovery system for raw gas from a coke oven is proposed, which only discloses a bridge pipe and a riser installed on the top of the coke oven to lead out the raw gas. A waste heat recovery device is connected between the riser and the bridge pipe. The raw gas first enters the device in a forward direction within a period of time, and tar and the like adhere to the outlet of the device; after being used for a period of time, the raw gas enters the heat exchange device in a reverse direction, so that the high-temperature raw gas first contacts the outlet of the heat exchange device, thereby reducing the problem of tar adhering to the wall.

[0004] Studies have shown that the heat brought out by raw coal gas accounts for about 35% of the total heat supplied to the coke oven. This is roughly equivalent to the heat brought out by red coke. The current main direction is how to improve the efficiency of the riser raw coal gas waste heat recovery and improve the safety and reliability of the waste heat recovery device. There has been no attention paid to how to reduce the amount of ammonia spraying and the amount of gas cooling water compared to before using the riser raw coal gas waste heat recovery device. The large amount of ammonia spraying not only makes it difficult to reduce the energy consumption of the ammonia transport power device, but also leads to an increase in the storage equipment for residual ammonia in the coke oven gas purification process, an increase in the energy consumption of the residual ammonia insulation equipment, and an increase in the amount of extractant added to the ammonia. The large amount of cooling water used in the horizontal tube cooler in the initial cooling process of the coke oven gas will make it difficult to reduce the energy consumption of the cooling water transport power device. Summary of the invention

[0005] Based on the above problems, the present invention proposes a method of evaluating the heat carried by the raw gas in the riser by combining the material and heat balance of the coke oven, evaluating the heat exchange efficiency of the raw gas in the heat balance of the riser waste heat recovery system, and further controlling the final temperature of the raw gas after heat exchange in the waste heat recovery system in combination with the dew point of the raw gas, so as to improve the heat exchange efficiency of the system and reduce the amount of circulating ammonia water spraying.

[0006] The present invention firstly monitors the data of the existing coke oven riser raw gas waste heat recovery, and then calibrates the riser raw gas waste heat recovery system, which mainly includes the following aspects:

[0007] (1) Calibrate the steam yield and output of the waste heat recovery system.

[0008] (2) Calibrate the effect of the waste heat recovery system on reducing the energy consumption of the coking process: reduction amount and reduction rate.

[0009] (3) Study the emission reduction effect of the waste heat recovery system: the corresponding CO2 emission reduction amount and emission reduction rate.

[0010] (4) Determine the temperature of the raw gas at the inlet and outlet of the riser heat exchanger and the degree of cooling of the raw gas.

[0011] (5) Calibrate the recovery rate of sensible heat of raw gas after passing through the waste heat recovery system.

[0012] (6) Calibrate the recovery rate of waste heat from raw coal gas after passing through the waste heat recovery system.

[0013] After calibrating the waste heat recovery rate of the raw gas, the amount of raw gas, the heat capacity of the raw gas (including the composition of the raw gas) and the temperature of the raw gas are determined, so as to obtain the amount of raw gas generated, the heat brought by the raw gas, and the sensible heat and latent heat of the raw gas; and then determine the water vapor production and yield through the material balance of the riser raw gas waste heat recovery system.

[0014] Finally, the heat recovered by the system, the recovery rate of the waste heat of the waste gas ...

[0015] According to the above recovery rate, the amount of circulating ammonia water spraying can be reduced by 18.74% accordingly.

[0016] At the same time, the energy-saving and emission-reduction effects of the system are evaluated based on the above recovery rate.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. Calibrate the riser raw gas waste heat recovery system with reference to the thermal calibration standards of the coke oven to fill the gap in the existing technology.

[0019] 2. During the calibration process of the riser raw gas waste heat recovery system, the raw gas waste heat recovery rate is calibrated. In this process, by determining the amount of raw gas, the heat capacity of raw gas, the temperature of raw gas, and the composition of raw gas, the heat brought out by the raw gas is obtained, which consists of sensible heat and latent heat. In addition, during the calibration process, the national standard GB / T33962-2017 "Coke Oven Thermal Balance Test and Calculation Method" is also used to determine the amount of raw gas generated, the heat brought out by the raw gas, and the sensible heat and latent heat of the raw gas; in order to ensure that the calibration process is within the error range.

[0020] 3. During the calibration process, the present invention obtains the recovery rate of the waste heat of the raw gas, that is, the heat of the raw gas recovered in the riser raw gas recovery system accounts for 30.04% of the sensible heat of the raw gas and 18.74% of the waste heat of the raw gas. Based on this recovery efficiency, the amount of circulating ammonia water spraying can be reduced by 18.74%.

[0021] 4. During the calibration process of the present invention, it was found that the average temperature of the raw gas in the first half of the coking period decreased from 692.4°C to 537.0°C. Although it decreased by 155.4°C, there is still 81.6°C of room for reduction to 450°C. The residence time of the raw gas in the riser can be controlled to reduce the temperature of the raw gas at the riser outlet, thereby further improving the heat exchange efficiency of the riser waste heat recovery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the riser and bridge pipe of the coke oven in the prior art;

[0023] Figure 2 This is the coke oven logistics diagram;

[0024] Figure 3 This is the heat flow diagram of the coke oven;

[0025] Figure 4 This is the logistics diagram of the riser waste gas waste heat recovery system;

[0026] Figure 5 This is the logistics diagram of the riser waste gas waste heat recovery system;

[0027] Figure 6 Flow chart of the calibration. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0031] At present, there are problems with the various ways of recycling the sensible heat of raw coal gas. Dust-containing gas will be obtained during the production process of coke oven gas. This part of gas is raw coal gas. Raw coal gas needs to be dust-removed before it can be supplied to users. According to relevant calculations, the heat brought by raw coal gas accounts for about 32%-35% of the total heat consumption of coking. Among them, the sensible heat above the dew point temperature of raw coal gas (about 70°C) can account for more than 50% of the total heat of raw coal gas. Under conventional processes, high-temperature raw coal gas (650-750°C) is directly cooled to about 83°C by spraying with circulating ammonia water, and then indirectly cooled to near the wet-bulb temperature by water in the horizontal tube primary cooler.

[0032] The circulating ammonia water drawn from the ammonia water tank by the existing circulating ammonia water pump first enters the heating heat exchanger to increase the temperature to 50-60℃, and then enters the bridge pipe for spraying. The existing cooling water needs to enter the waste heat refrigerator to cool down to about 20℃, and then circulate to the horizontal pipe primary cooler through the water pump. After using the coke oven riser raw gas waste heat recovery device to recover part of the raw gas sensible heat, there are still other problems in using the original process parameters of these two methods to cool the coke oven gas, as follows:

[0033] When the temperature of the circulating ammonia water sprayed in the bridge pipe decreases, the temperature of the circulating ammonia water in the gas collecting pipe will also decrease, causing the viscosity of the tar to increase, affecting the gas and tar transportation of subsequent pipelines such as the gas collecting pipe and the air intake pipe, as well as the effect of tar separation in the mechanized ammonia water clarification tank.

[0034] Therefore, the present invention provides a method for evaluating the waste heat recovery efficiency of raw gas in a coke oven riser and its application in reducing the amount of circulating ammonia water spraying.

[0035] If you want to know the utilization rate of the waste heat recovery system of the raw coal gas, you need to calibrate the riser waste heat recovery system of the raw coal gas, that is, the calibration of the waste heat recovery rate of the raw coal gas. To determine the recovery rate of the waste heat of the raw coal gas, it is necessary to determine the amount of heat brought out by the raw coal gas. To determine the amount of heat brought out by the raw coal gas, it is necessary to determine the amount of raw coal gas, the heat capacity of the raw coal gas and the temperature of the raw coal gas. To determine the heat capacity of the raw coal gas, it is necessary to determine the composition of the raw coal gas. The heat brought out by the raw coal gas consists of two parts: sensible heat and latent heat. At the same time, during the entire coking process, the amount of raw coal gas generated, the composition of the raw coal gas, and the temperature of the raw coal gas are all changing. At present, the amount of raw coal gas generated and the composition of the raw coal gas in the coking process cannot be directly measured.

[0036] Therefore, the present invention adopts the national standard GB / T33962-2017 "Coke Oven Heat Balance Test and Calculation Method" to determine the amount of raw gas generated, the heat brought by the raw gas, and the sensible heat and latent heat of the raw gas. Then the water vapor production and yield are determined by the material balance of the riser raw gas waste heat recovery system.

[0037] Finally, the heat balance of the riser waste gas heat recovery system is used to determine the heat recovered by the system, the recovery rate of the waste gas heat, and the recovery rate of the sensible heat of the waste gas. Based on this, the energy saving effect and emission reduction effect of the system can be evaluated. Figure 6 shown.

[0038] The following embodiments are based on a coking riser waste gas heat recovery system as the test object. The system was designed, constructed and put into operation at the same time as the coke oven. Each group of coke ovens (2×70 holes) is equipped with a vaporization station, and the two vaporization stations are independent of each other. In each vaporization station, two coke ovens share a deaerator. Each coke oven is equipped with a steam drum. The two steam drums are connected. The steam generated by the two steam drums converges in the sub-cylinder, and then part of it is incorporated into the steam external pipeline network and part of it is used for thermal deoxygenation of this system. This embodiment uses the 155# carbonization chamber of the 3# coke oven and the 214# carbonization chamber of the 4# coke oven in the coke oven as the measurement objects for data testing and statistics.

[0039] Example 1

[0040] 1. Testing and data processing of the riser waste gas waste heat recovery system

[0041] The items measured on site include: raw gas temperature, coke cake temperature, small flue temperature, furnace surface temperature, excess air coefficient, surface temperature of each equipment and pipeline of the riser raw gas waste heat recovery system, etc.

[0042] The items counted by production data include: coke oven production data (including input coal, product yield, heating gas), riser raw gas waste heat recovery system production data, etc.

[0043] (1) Measurement of raw gas temperature

[0044] The raw gas temperature is measured by embedding thermocouples and configuring paperless recorders to continuously measure the raw gas temperature during the entire coking process online, and measure 1-2 coking cycles. Measure the temperature at the inlet, outlet and bridge pipe of the riser heat exchange section. The 3# coke oven measures the 155# carbonization chamber, and the 4# coke oven measures the 214# carbonization chamber.

[0045] The temperature data corresponding to the measured raw gas temperature curve is exported, and the average value of each temperature is calculated in accordance with the provisions of the national standard GB / T 33962-2017 "Coke Oven Thermal Balance Test and Calculation Method".

[0046] The calculation results are shown in Table 1 below.

[0047] Table 1 Average temperature of raw gas

[0048]

[0049] It can be seen from the data in Table 1 that the average temperature between different coking cycles of the same carbonization chamber and between different carbonization chambers is very similar, which shows that the coke oven production was stable during the test, the raw gas temperature measurement method was appropriate, and the data was accurate and reliable.

[0050] (2) Measurement of coke cake temperature

[0051] The coke cake temperature was measured with a coke cake temperature measuring instrument and calibrated with an infrared thermometer. Three carbonization chambers were measured in each coke oven, and the average value was taken as the coke cake temperature. The measurement results are shown in Table 2.

[0052] (3) Measurement of small flue temperature

[0053] The temperature of the small flue was measured by embedding thermocouples and configuring a paperless recorder to continuously measure the exhaust gas temperature during the entire reversing cycle. The small flue on the coke side of the coke oven was measured separately for 2-4 reversing cycles, and the average value was taken as the temperature of the small flue. The measurement results are shown in Table 2.

[0054] (4) Measurement of excess air coefficient

[0055] A portable gas analyzer is used to measure the exhaust gas composition at the small flue, and then the gas coefficient K is calculated based on the heating gas composition, and then the excess air coefficient at the small flue is calculated.

[0056] One sign number is measured on the coke side of each coke oven, and the average value is taken as the excess air coefficient of the coke oven.

[0057] The measurement results are shown in Table 2.

[0058] Table 2 Coke cake temperature, small flue temperature and excess air coefficient

[0059]

[0060] (5) Measurement of coke oven body surface temperature

[0061] The surface temperature of the coke oven body is measured with an infrared thermometer. According to the national standard GB / T33962-2017 "Coke Oven Thermal Balance Test and Calculation Method", the temperatures of the roof, coke machine side, heat storage chamber, resistance wall and other parts of the two coke ovens are measured respectively.

[0062] At the same time, wind speed and atmospheric temperature measuring instruments are used to measure the corresponding ambient temperature and wind speed at each part.

[0063] The measurement results are shown in Table 3.

[0064] Table 3 Coke oven body surface temperature

[0065]

[0066]

[0067] (6) Measurement of the surface temperature of each device and pipeline in the riser raw gas waste heat recovery system

[0068] The surface temperature of each device and pipeline of the riser raw gas waste heat recovery system is measured by infrared thermometer. The surface temperature of the deaerator, steam drum, and pipelines of the system are measured separately.

[0069] At the same time, wind speed and atmospheric temperature measuring instruments are used to measure the corresponding ambient temperature and wind speed at each part.

[0070] The measurement results are shown in Table 4.

[0071] Table 4 Surface temperature of each equipment and pipeline in the riser raw gas waste heat recovery system

[0072]

[0073] Table 4

[0074]

[0075] (7) Measurement of riser surface temperature

[0076] The surface temperature of the riser is measured using an infrared thermometer.

[0077] Measure the surface temperature of all riser pipes.

[0078] The surface temperature measurement results of each riser heat exchange section are shown in Table 5.

[0079] Table 5 Surface temperature of the riser heat exchange section

[0080] project 3# New coke oven 4# coke oven average Maximum temperature / ℃ 59.5 52.5 56.0 Minimum temperature / ℃ 42.5 41.5 42.0 Average temperature / ℃ 50.0 47.2 48.6

[0081] 2. Statistics of production data

[0082] The production data includes the production data of the coke oven and the production data of the riser raw gas waste heat recovery system.

[0083] (1) Coke oven production data

[0084] Coke oven production data includes coal input, product yield, heating gas, etc.

[0085] 1) Parameters of coal entering the furnace

[0086] The parameters of the coal entering the furnace are shown in Tables 6 and 7.

[0087] Table 6 Turnaround time, average wet coal loading per hole, hourly coal loading of coke oven, etc.

[0088]

[0089] Table 7 Industrial analysis and elemental analysis of coal and coke fed into the furnace

[0090]

[0091] 2) Yield of each coking product

[0092] The yields of various coking products are shown in Table 8

[0093] Table 8 Product yield (dry basis)

[0094]

[0095] 3) Heating gas

[0096] The parameters of heating gas are shown in Table 9.

[0097] The composition of the heating gas is shown in Table 10.

[0098] Table 9 Heating gas parameters

[0099]

[0100] Note: The gas flow in the table is the standard flow after conversion.

[0101] Table 10 Composition and calorific value of heating gas

[0102]

[0103] Dw=(12730CO+10840H2+35840CH4+71170CmHn) / 100kJ / m 3

[0104]

[0105] (2) Production data of the riser raw gas waste heat recovery system

[0106] The temperature, pressure and flow rate at each point of the riser raw gas waste heat recovery system during the calibration period are shown in Table 11.

[0107] Table 11 Steam system inlet water temperature and drum outlet steam temperature, pressure, flow rate, etc.

[0108]

[0109] 3. Gas combustion calculation

[0110] Through the combustion calculation of coal gas, we can obtain the coal gas coefficient K for calculating excess air, the required amount of air, the amount of waste gas generated, the composition of the waste gas, etc.

[0111] The combustion calculation of coke oven gas for heating is shown in Table 12.

[0112] The relevant parameters of coke oven gas combustion are shown in Table 13.

[0113] Table 12 Calculation of coke oven gas combustion (based on 100m 3 Dry gas as the basis)

[0114]

[0115]

[0116]

[0117] Table 13 can be obtained from Table 12.

[0118] Table 13 Coke oven gas combustion related parameters

[0119]

[0120] 4. Material balance and heat balance of coke oven.

[0121] To analyze the sensible heat recovery rate of raw coal gas, it is necessary to know the amount of heat carried away by the raw coal gas when it leaves the coke oven. To know the amount of heat carried away by the raw coal gas when it leaves the coke oven, it is necessary to know the amount and composition of the raw coal gas, that is, the material balance of the coke oven must be performed first. To know the proportion of the waste heat carried by the raw coal gas leaving the coke oven to the total coking heat and the proportion of the sensible heat in the raw coal gas, it is necessary to perform the heat balance of the coke oven. Therefore, the material balance and heat balance of the coke oven must be performed first. 1t (1000kg) of wet coal entering the furnace is used as the calculation basis.

[0122] 4.1. Material balance of coke oven carbonization chamber

[0123] (1) Material entry

[0124] Material input includes dry coal quantity G M , the amount of water brought into the coal entering the furnace G s .

[0125] Dry coal quantity:

[0126] In the formula: GM is dry coal mass, kg / t; M is moisture content of coal entering the furnace, %; 1000 is the base number for material balance calculation.

[0127] Amount of water brought into the coal:

[0128] In the formula: G5 is the amount of water brought into the coal entering the furnace, kg / t, M is the moisture content of the coal entering the furnace, %.

[0129] The total amount of materials input is,

[0130] ∑G=G M +G s =1000

[0131] ∑G=G M +G s =885.2+114.8=1000kg / t

[0132] (2) Material input and output

[0133] Material input and output include: dry total coke volume G J , tar amount G JY , crude benzene amount G B , Ammonia content G A , Net gas volume G MQ , combined water content G SX , the amount of water brought into the coal entering the furnace G s .

[0134] Specific:

[0135] 1) Dry total focus:

[0136] Where: K Jd ——Full coke rate of coal fed into the furnace on a dry basis, %; M——Moisture content of coal fed into the furnace, %.

[0137] 2) Tar content:

[0138] Where: G JY ——Tar content, kg / t; K JY ——Dry basis tar yield of coal entering the furnace, %; M——Water content of coal entering the furnace, %. 3) Crude benzene content:

[0139] Where: M——moisture content of coal entering the furnace, %; K B·d ——Crude benzene yield on dry basis of coal entering the furnace, %.

[0140] 4) Ammonia content:

[0141] Where: K A·d —Dry basis ammonia yield of coal entering the furnace, %; M——moisture content of coal entering the furnace, %.

[0142] 5) Net gas volume:

[0143] Where: K MQ.d ——Net gas yield on dry basis of coal entering the furnace, %; M——Moisture content of coal entering the furnace, %.

[0144] 6) Combined water content:

[0145] Where: K sx ——Combined water yield of coal fed into the furnace on a dry basis, %;

[0146] K sx.a It is advisable to calculate according to the following formula:

[0147] Where: a is the conversion coefficient of total oxygen in coal into combined water, preferably 0.3 to 0.5, preferably 0.4;

[0148] O M·d —— oxygen content of coal on dry basis, %; 18—— relative molecular mass of water; 16—— relative atomic mass of oxygen. Therefore, the total output of materials is:

[0149] ∑G′=G J +G JY +G B +G A +G MQ +G sx +G s

[0150] =683.37+26.38+8.50+2.30+144.46+17.88+114.80

[0151] =997.70kg / t

[0152] (3) Material balance difference

[0153] ΔG=∑G-∑G′=1000-997.70=2.30kgkJ / t

[0154] Relative error: 2.30 / 1000 = 0.0023 = 0.23%

[0155] The error is no more than 5%, indicating that the data is reasonable and the amount and composition of the raw gas are credible.

[0156] The material balance table can be obtained from the above calculations, see Table 14.

[0157] Table 14 Material balance based on 1 t of wet coal

[0158]

[0159]

[0160] For the convenience of discussion, the various items of raw gas are combined into Table 15.

[0161] Table 15 Material balance based on 1 t wet coal

[0162]

[0163] For the convenience of discussion, Table 15 is converted to tons of coke as shown in Table 16.

[0164] Table 16 Material balance based on 1t dry coke

[0165]

[0166] The data in Table 16 show that for every ton of dry coke produced, 1295.35 kg of dry coal is required, 167.99 kg of water, i.e. 1463.34 kg of wet coal, is brought into the coke oven, and 459.97 kg of raw coal gas is produced.

[0167] The data in Table 16 can be used to draw a coke oven logistics diagram, such as Figure 2 shown.

[0168] 4.2 Coke oven heat balance

[0169] (1) Heat input

[0170] The heat input includes the combustion heat of heating gas Q1, the sensible heat of heating gas Q2, the combustion heat of leaked raw gas Q3, the sensible heat of combustion air required for heating gas and leaked raw gas Q4, the sensible heat brought in by dry coal Q5, and the sensible heat of water brought in by the coal entering the furnace Q6.

[0171] 1) Heating gas combustion: Q1 = Q Dw ×V omq

[0172] Where: Q Dw ——lower calorific value of dry gas, kJ / m 3 ;

[0173] V omq ——Amount of dry gas required per ton of coal fed into the furnace, m 3 / t;

[0174]

[0175] Where: τ——turnaround time, τ=28h;

[0176] V——heating gas flow rate of each coke oven, the value is 44600m 3 / h

[0177] N——Number of carbonization chamber holes in each coke oven, N=140;

[0178] G'—the amount of coal loaded in each carbonization chamber.

[0179] 2) Sensible heat of heating gas: Q2 = V MQ (C MQ +C SQ gm)t MQ

[0180] Where: t MQ ——Gas temperature, °C;

[0181] C SQ - specific heat of water vapor in heating gas;

[0182] g m ——moisture content of heating gas on dry basis;

[0183] C MQ ——Specific heat of heating gas, kJ / m 3 ℃

[0184] λ MQ =0.01(C Co CO+C CO2 CO2+C H2 H2+C CH4 CH4+……)

[0185] Where: Cco, Cco2, CH2...——average specific heat of corresponding components in heating gas, kJ / m 3 ℃.

[0186] 3) Combustion heat of leaked raw gas:

[0187] Where: Q DW ——low calorific value of clean coal gas, kJ / m 3 ,

[0188] ——The amount of raw gas leaking from the carbonization chamber into the heating system, m 3 / h; G——coal loading capacity, t / h.

[0189] 4) Sensible heat of combustion air required for heating gas and leaking raw gas:

[0190]

[0191] Where: V OJ ——Standard flow rate of heating gas required for wet coal, 1m 3 / t;

[0192] L 1J , L 1h ——The actual dry air requirement for burning heating gas and leaking into the raw gas, calculated by the combustion, m 3 / m 3 ;

[0193] t KQ ——Average air temperature in the heat storage room corridor, °C; t KQ =40℃

[0194] C KQ ——Average specific heat capacity of air at 0~tкο℃, kJ / (m 3 ·℃).

[0195] C KQ =C kq +C sq g k

[0196] Where: C kq - the average specific heat of dry air, ℃;

[0197] C sq ——Average specific heat of water vapor in air, kJ / m 3 ℃;

[0198] g k ——Dry basis content of water vapor in the air, m 3 / m 3 .

[0199] 5) Sensible heat brought in by dry coal: Q5 = G M C M t M , kJ / t

[0200] Where: t m ——Coal temperature entering the furnace, C m ——Average specific heat of coal entering the furnace, kJ / kg℃,

[0201]

[0202] Where: A Md ——Dry basis ash content of coal entering the furnace.

[0203] 6) Sensible heat of water brought into the furnace by coal: Q6 = G s C s t m ,

[0204] Where: G s ——The amount of water brought into the coal entering the furnace, C s ——average specific heat of water, t M ——The degree of coal entering the furnace.

[0205] Therefore, the above calories are calculated as follows:

[0206] ∑Q=Q1+Q2+Q3+Q4+Q5+Q6

[0207] =2516448+10784+98682+48562+23281+11968

[0208] =2709724kJ / t

[0209] (2) Heat output

[0210] The heat output includes the heat brought by coke Q1′, the heat brought by tar Q2′, the heat brought by benzene Q3′, the heat brought by ammonia Q4′, the heat brought by clean coal gas Q5′, the heat brought by water vapor Q6′, the heat brought by flue gas Q7′, the heat brought by incomplete chemical combustion loss Q8′, and the heat lost by the furnace body Q9′.

[0211] 1) Heat brought out by coke: Q1′=G J CJ J t J

[0212] Where: t j ——Average coke temperature, C J ——The average specific heat of coke can be calculated as follows:

[0213]

[0214] Where: C JA ——Specific heat of ash in coke, kJ / kg℃;

[0215] A Jd ——Ash content of coke on dry basis;

[0216] C JFC ——Specific heat of fixed carbon in coke, kJ / kg℃;

[0217] FC Jd——fixed carbon on dry basis of coke;

[0218] C v ——Specific heat of volatile matter in coke;

[0219] V Jd ——volatile matter on dry basis of coke;

[0220] r3——weight of volatile matter in coke, kg / m 3 .

[0221] 2) Heat brought out by tar: Q2′=G JY (418.68+C JY t lh )

[0222] Where: G JY ——Amount of tar obtained from 1000kg of wet coal;

[0223] t 1h ——Average temperature of raw coal gas in the first half of the coking cycle;

[0224] C JY ——Average specific heat of tar, kJ / kg℃.

[0225] 3) Heat removed by benzene: Q3′=G B (431+C Bq t 1h )

[0226] Where: C Bq ——Average specific heat of crude benzene gas, t 1h ——Average temperature of raw coal gas in the first half of the coking cycle.

[0227] 4) Heat brought out by ammonia: Q4′=G A C A t h

[0228] Where: C A ——Ammonia at 0~t h Average specific heat between ℃, t h ——Raw coal gas temperature during coking cycle, ℃.

[0229] 5) Heat brought out by clean gas:

[0230] Where: C 1h ——In t 1h Average specific heat of gas, kJ / m 3 ℃,

[0231] C 2h ——At t2 h Average specific heat of gas, kJ / m 3℃

[0232] G MQ ——Gas output, kg / t; r MQ ——Gas density, kg / m 3 .

[0233] 6) Heat consumed by water vapor: Q6′ = Q 6-1 ′+Q 6-2 ′+Q 6-3 '

[0234] Where: Q6-1'--heat consumed by moisture brought into the coal entering the furnace, kJ / t

[0235] Q6-2'--The heat consumed and brought out by combined water in the process of generation, kJ / t

[0236] Q6-3'--heat consumed by the reaction of water vapor and coke, kJ / t;

[0237] Q 6-1 ′=G S (2500.8+C sq t 1h )

[0238] Q 6-2 ′=(0.25G s +1.25G sx )[C sq ′(t 1h -450)-2093]

[0239] Q 6-3 ′=6594×0.25(G s +G sx )

[0240] C sq --In (0~t lh Average specific heat of water vapor between ℃, see Table C sq =2.039 kJ / kg℃;

[0241] C sq '--Average specific heat of water vapor between 0 and 450°C, see Table C sq =1.957kJ / kg℃.

[0242] 7) Heat carried away by flue gas:

[0243] Where: V MQ --Standard flow rate of heating gas required for coal entering the furnace, m 3 / t;

[0244] V n--The actual flue gas volume when the gas is completely burned, obtained through combustion calculation, m 3 / m 3 ;

[0245] d-- correction factor of smoke volume during incomplete combustion;

[0246] C JF --From (0~t f Average specific heat capacity of flue gas, kJ / (m 3 ℃);

[0247] t F ——Average flue gas temperature, °C; From the table, we know that t F =292.7℃;

[0248] φ--Amount of raw gas leaking from the carbonization chamber into the heating system, m 3 / h;

[0249] G——Total coal load in the furnace, kg / h.

[0250] 8) Heat loss from incomplete chemical combustion:

[0251]

[0252] Where: V oJ ——Standard flow rate of heating gas required for coal entering the furnace, m 3 / t;

[0253] CO, H2, CH4 - the corresponding volume fraction of each component in dry flue gas, %; from Table 3-12, we know that CO = 0.22%, and the others are all 0.

[0254] φ——Amount of raw coal gas leaking from the carbonization chamber into the heating system, m 3 / h;φ=0m 3 / h;

[0255] G——Full furnace coal loading, kg / h;

[0256] d——Correction coefficient of smoke volume during incomplete combustion; from 4.2.2.8, we know that d = 1.0011

[0257] V——the amount of flue gas generated by complete combustion of coal gas, m 3 / m 3 .

[0258] 9) Heat loss from furnace:

[0259]

[0260] Where: q s1 ——heat dissipation from furnace surface, kJ / t;

[0261] q s2 ——Heat transferred from the furnace foundation to the ground, kJ / t;

[0262] q s3 ——Heat loss when the furnace door is opened, kJ / t;

[0263] α f ——Radiative heat transfer coefficient, kJ / (m 2 h℃);

[0264] α α ——Convection heat transfer coefficient, kJ / (m 2 h℃);

[0265] F——heat dissipation area of ​​each part of the carbonization chamber furnace, m 2 ;

[0266] t b ,t α ——respectively furnace surface temperature and ambient temperature, ℃;

[0267] G'——the amount of coal loaded in each carbonization chamber, t.

[0268] τ——surrounding time, h.

[0269] Therefore, the above calorie calculation result is:

[0270] ∑Q'=Q1'+Q2'+Q3'+Q4'+Q5'+Q6'+Q7'+Q8'+Q9'

[0271] =1020765+48754+15540+4273+344079+588155+427168+29323+294718

[0272] =2779142kJ / t

[0273] (3) Thermal balance difference

[0274] △Q=∑Q-∑Q'=2709724-2779142=-69418kJ / t

[0275] Relative error: -69418 / 2709724 = -0.0256 = -2.56%

[0276] The error is less than 5%, indicating that the data is reasonable. Therefore, the heat brought out by the raw coal gas is credible.

[0277] The heat balance of coking coal is shown in Table 17.

[0278] Table 17 Coke oven heat balance based on 1 t wet coal

[0279]

[0280] Table 17

[0281]

[0282]

[0283] For the convenience of discussion, similar items are combined to obtain Table 18.

[0284] Table 18 Coke oven heat balance based on 1 ton of wet coal (1 ton of wet coal as the calculation basis)

[0285]

[0286] The heat brought out by raw coal gas* is a customary term. It includes the heat of formation of chemical water (exothermic) and the heat of reaction between water and coke (endothermic), and the latter is greater than the former. Therefore, the heat brought out by raw coal gas is less than 1007166kJ / t.

[0287] As shown in Table 18, among the contributions to heat input, heating gas accounts for the most, accounting for 93.27%, followed by leaked raw coal gas, accounting for 3.64%. Among the heat output, heat brought out by coke accounts for 37.67%, heat brought out by raw coal gas accounts for 37.17%, of which moisture accounts for 21.71%, accounting for more than half of the heat brought out by raw coal gas. Heat brought out by flue gas accounts for 16.84%.

[0288] The heat brought out by coke and flue gas has been recovered, and the recovery of waste heat from waste gas is of great significance and imperative.

[0289] For the convenience of comparison, Table 18 is converted into Table 19 based on tons of coke.

[0290] Table 19 Coke oven heat balance table based on 1 ton of coke (calculation basis: 1 ton of coke)

[0291]

[0292] From Table 19, we can see that for every ton of coke produced, the raw coal gas brings out 1473822 kJ of heat, which is about 50.37 kg of standard coal. At the same time, from Table 19, we can see that the heat brought out by the raw coal gas is equivalent to the heat brought out by coke.

[0293] From the data in Table 19, the heat flow diagram of the coke oven can be drawn, such as Figure 3 shown.

[0294] The above calibration is the ratio of the heat brought out by the raw gas from the coke oven to the input heat of the coke oven, and is the reference value calibrated according to the national standard in each season after the coke oven is put into operation. There is no need to repeat the calibration in the subsequent evaluation method of the waste heat recovery efficiency of the raw gas in the coke oven riser. The input heat of the coke oven can be calculated by the heating gas calorific value and consumption, air calorific value and consumption, and furnace coal calorific value and consumption collected by the coke oven heating industrial control computer, with an error of 3.64%. The air consumption is calculated based on the real-time measured excess air coefficient and heating gas consumption.

[0295] 4.3 Latent heat and sensible heat of raw coal gas

[0296] It is divided into latent heat and sensible heat. Tar, crude benzene and water are all liquid at room temperature, so they bring out both latent heat and sensible heat, while ammonia and clean coal gas only have sensible heat.

[0297] Table 20 Latent heat, sensible heat and proportion of each component in raw coal gas (based on 1 t wet coal)

[0298]

[0299] It can be seen from Table 20 that 79.96% of the heat brought out by tar is sensible heat and can be recovered, 75.48% of the heat brought out by crude benzene is sensible heat and can be recovered, and only 36.08% of the heat brought out by water vapor is sensible heat and can be recovered.

[0300] Therefore, the total heat brought out by the raw gas leaving the coke oven is: 937536kJ / t;

[0301] The latent heat of tar, crude benzene and water: 346515 kJ / t, which cannot be recovered;

[0302] Total sensible heat: 591021 kJ / t, this part of heat can be recovered.

[0303] The proportion of sensible heat to the total heat brought out by the raw coal gas is: the proportion of sensible heat in the raw coal gas = 63.04%.

[0304] That is to say, of the heat brought by the raw coal gas, 63.04% is recoverable by this technology, while 36.96% is not recoverable by this technology.

[0305] 5. Material balance and heat balance of the riser raw gas waste heat recovery system.

[0306] In this step, a coke oven riser waste gas waste heat recovery system put into use in a coking plant is tested and the production data of the system operation is analyzed.

[0307] 5.1. Material Balance

[0308] (1) Material entry

[0309] The input of materials includes raw gas G h and deoxygenated water Gc. Since the flue gas in and out of the riser during the cooling period cannot be measured and the in and out quantities are the same, it is not considered here. In addition, the leakage of the pipeline is not considered.

[0310] (2) Material delivery

[0311] The output of materials includes raw gas G h , the amount of water vapor generated Gz, and the amount of sewage discharged Gp.

[0312] The material balance tables of the system are shown in Tables 21 and 22.

[0313] Table 21 System material balance based on 1 t of wet coal entering the furnace

[0314]

[0315] If calculated based on 1t of coke, it would be as shown in Table 22.

[0316] Table 22 System material balance based on 1t of coke

[0317]

[0318] From Table 22, we can see that every 1t of coke produced consumes 97.78kg of desalted water and generates 96.80kg of water vapor. From Table 22, we can draw the logistics diagram of the riser waste gas waste heat recovery system, as shown in Figure 4 shown.

[0319] 5.2 Heat balance

[0320] (1) Heat input

[0321] The heat input of the riser raw gas waste heat recovery system includes the heat Q brought in by the raw gas leaving the coke oven. h , the heat brought in by desalted water Q c The heat Q transferred by the graphite flame gas and the coal loading time to the water in the riser R .

[0322] 1) From Table 20, we can see that the heat brought into the coke oven by the raw gas is: Q h =937536kJ / t,

[0323] 2) Heat brought in by desalted water: Q C =G c H c =6991kJ / t,

[0324] In the above formula: G c ——Deionized water quantity, G in Table 21c =66.82kg / t, H c ——Enthalpy of desalted water, at 25℃, H c =104.63kJ / kg.

[0325] 3) Heat transferred from graphite flame to water during cooling time:

[0326] In the above formula: K'=107.05J / s·m 2 K = 0.10705 kJ / s m 2 ℃——heat transfer coefficient of the riser,

[0327] F=3.14×0.748×3.40=7.99m 2 ——Heat exchange area of ​​a single riser, m 2 ;

[0328] △t——the average temperature difference between flame gas and water, ℃;

[0329]

[0330] In the above formula: t1——the temperature of the combustion exhaust gas entering the riser, t1=1300℃

[0331] t1'——circulating water temperature entering the riser heat exchanger, t1'=165.9℃

[0332] t2——combustion exhaust gas temperature leaving the riser heat exchanger, t2=1200℃

[0333] t2'——circulating water temperature leaving the riser heat exchanger, t2′=175.5℃.

[0334] τ R =20×60=1200s——cooling time, seconds;

[0335] G'=59.14t——the amount of wet coal loaded in a single carbonization chamber, t.

[0336] so,

[0337]

[0338] In the above formula: K - heat transfer coefficient from combustion exhaust gas (flame) to circulating water, J / s·m 2 K;

[0339] α1——Heat transfer coefficient from combustion flame to heat exchange wall of riser, J / s·m 2 K;

[0340] α2——Heat transfer coefficient from the heat exchange wall of the riser to the circulating water, ” / s·m 2 K;

[0341] λ——Thermal conductivity of the heat exchange wall of the riser, J / s·m·K; λ=45.3J / s·m·K

[0342] b——the thickness of the riser heat exchange wall, m; b=0.020m.

[0343] a1=0.75(a 对 +a 辐 )

[0344] In the above formula: α 对 ——Convective heat transfer coefficient, ” / s·m 2 K;

[0345] a 辐 ——Radiation heat transfer coefficient, J / s·m 2 K;

[0346]

[0347] Where: T——average air flow temperature, K

[0348] d——equivalent diameter of the barrel in the riser, m;

[0349] u——the flow rate of combustion exhaust gas (flame), m / s;

[0350] cp——Specific heat capacity of combustion exhaust gas (flame) at constant pressure, kJ / kg·K;

[0351] ρ——Density of combustion exhaust gas (flame), kg / m 3 .

[0352] μ——Viscosity of combustion exhaust gas (flame), Pa·s.

[0353] The exhaust gas composition is close to that of air when burned at 1200℃.

[0354] T=1573K

[0355] d=0.70m

[0356] u=15m / s

[0357] c p =1.177 kJ / kg K = 1177 J / kg * K;

[0358] ρ=0.224kg / m 3

[0359] μ=5.61×105 Pa….

[0360]

[0361] α 辐 =α CO2 +α H2O =86.11J / s·m 2 K,

[0362] a CO2 =30.55J / s·m 2 K, α H2O =55.56J / s·m 2 ·K

[0363]

[0364] In the above formula: λ = 0.684 J / s·m·K - thermal conductivity of circulating water, J / s·m·K;

[0365] ——equivalent diameter of riser water jacket, m;

[0366] u=8.0m / s——Flow rate of circulating water, m / s;

[0367] C p =4.312kJ / kg·K=4312J / kg·K——Specific heat capacity of circulating water at constant pressure, kJ / kg·K;

[0368] ρ=917kg / m 3 ——Density of circulating water, kg / m 3 .

[0369] μ=0.186mPa…=0.186×10 -3 pa…s——Viscosity of circulating water, Pa·s.

[0370]

[0371]

[0372] 4) Total calories of the formula:

[0373] ∑Q”=Q h +Q c +Q R =937536+6991+18223=962750kJ / t

[0374] (2) Heat output

[0375] The heat output of the riser raw gas waste heat recovery system includes the heat Qh" taken away by the raw gas leaving the riser heat exchanger, the heat Q Z , the heat carried away by sewage Q P And the system dissipated heat Qss'. Among them, the heat Qh" brought out by the raw gas leaving the riser heat exchanger includes the heat Q1" brought out by tar, the heat Q2" brought out by benzene, the heat Q3" brought out by ammonia, the heat Q4" brought out by clean gas, and the heat Q5" brought out by water vapor.

[0376] 1) The heat Qh" taken out by the raw gas from the riser heat exchanger includes the following parts:

[0377] (a) Tar takes away heat: Q1″=G JY (418.68+C JY t 1h′ )=41615kJ / t,

[0378] In the above formula: G JY = -1000kg wet coal tar amount, G in Table 14 JY =26.38kg / t,t 1h’ ——The average temperature of the raw gas in the first half of the coking period after heat exchange, t in Table 1 1h’ =537.0℃,C JY ——Average specific heat of tar, C JY =1.277+1.641×10 -3 t 1h , =2.158kJ / kg℃.

[0379] (b) Heat removed by benzene: Q2" = G B (431+C BQ t 1h′ )=11496kJ / t,

[0380] In the above formula: G B ——Benzene production, G in Table 14 B =8.50kg / t, C BQ ——Average specific heat of crude benzene gas, t 1h ——Average temperature of raw gas in the first half of the coking cycle after heat exchange. C BQ =1.0258+1.2853×10 -3 t 1h′ =1.0258+1.2853×10 -3 ×537.0=1.716kJ / kg℃.

[0381] (a) Heat removed by ammonia: Q3" = G A C A t h=2987kJ / t,

[0382] In the above formula: G A ——Ammonia production, G in Table 14 A =2.30kg / t, C A ——Ammonia at 0~t n Average specific heat between ℃, C A =2.501kJ / kg℃,t h ----Raw gas temperature during coking period after heat exchange, t in Table 1 h =519.2℃.

[0383] (d) Heat carried away by clean gas:

[0384] In the above formula: C 1h ——After heat exchange at t 1h’ Average specific heat of gas, kJ / m 3 ℃

[0385] C 2h ——After heat exchange at t 2h Average specific heat of gas at ', kJ / m 3 ℃

[0386] G MQ ——Gas production, G in Table 14 MQ =144.46kg / t, r MQ ——Gas gravity, r in Table 10 MQ =0.480kg / m 3 .

[0387] Table 23 Average specific heat of each component in coal gas between 0 and 537.0℃, coal gas composition and C 1h Calculation of

[0388] composition <![CDATA[CO2]]> CO <![CDATA[H2]]> <![CDATA[CH4]]> Cm <![CDATA[O2]]> <![CDATA[N2]]> ∑XiCi Xi / % 19.14 23.82 4.47 0.51 0.05 0.57 51.43 <![CDATA[Ci / kJ / m 3 ℃]]> 1.996 1.351 1.308 2.197 3.486 1.399 1.339 1.472

[0389] Table 23 Average specific heat of each component in coal gas between 0 and 502.3℃, coal gas composition and C 2h 'Calculation

[0390] composition <![CDATA[CO2]]> CO <![CDATA[H2]]> <![CDATA[CH4]]> Cm <![CDATA[O2]]> <![CDATA[N2]]> ∑XiCi Xi / % 19.14 23.82 4.47 0.51 0.05 0.57 51.43 <![CDATA[Ci / kJ / m 3 ℃]]> 1.975 1.346 1.307 2.149 3456 1.392 1.334 1.464

[0391] (e) Heat brought by water vapor: Q5" = (G S +G SX )(2500.8+C SQ t 1h′ )=473378kJ / t, where: C SQ ——After heat exchange at 0~t 1h Average specific heat of water vapor between ℃, CSQ =1.987kJ / kg℃,t 1h’ ——Raw gas temperature in the first half of coking after heat exchange, t 1h ′=537.0℃,t 2h ——Raw gas temperature in the second half of coking after heat exchange, t 2h =502.3℃.

[0392] Therefore, the heat taken out by the raw gas leaving the riser heat exchanger is:

[0393] Q h "=Q1"+Q2"+Q3"+Q4"+Q5"=761829kJ / t.

[0394] 2) Heat taken away by water vapor: Q z =G z H z =184557kJ / t,

[0395] In the above formula: G z ——Water vapor production, Gz=66.82kg / t in Table 21, H z ——Thermal enthalpy of water vapor, Hz=2762kJ / kg.

[0396] 3) Heat brought out by sewage: Q p =G p H p =517kJ / t,

[0397] In the above formula: G p ——Sewage discharge volume, G in Table 21 p =0.67kg / t, H p ——Enthalpy of separation of water.

[0398] 4) Heat loss from steam system: H p =771 kJ / kg. In the above formula: a f ——Radiative heat transfer coefficient, kJ / (m 2 ·h·℃);

[0399] a a ——Convection heat transfer coefficient, kJ / (m 2 ·h·℃);

[0400] F'——system equipment and pipeline heat dissipation area, m 2 ;

[0401] t b ,t e ——respectively, system equipment, pipeline surface and ambient temperature, ℃;

[0402] G'——coal loading in carbonization chamber, t; G′=140×59.14t.

[0403] τ——coke oven turnover time, h; τ=28h.

[0404] Radiation heat transfer coefficient (α f ) should be calculated as follows:

[0405]

[0406] Where: T b 、T e ——are the absolute temperatures of furnace surface and environment, K;

[0407] Wind speed is W F ≤5m / s:

[0408] α f =22.2+15.1W F

[0409] When the wind speed is WF>5m / s:

[0410]

[0411] Where: W F ——wind speed (m / s).

[0412] Therefore, the heat output of the riser preheating recovery system is calculated as: ∑Q″′=Q h "+Q z +Q p +Qss'=972009kJ / t.

[0413] (3) Thermal balance difference

[0414] △Q”=heat input ∑Q”-heat output ∑Q″′=-9259kJ / t

[0415] Relative error: -9259 / 962750 = -0.96%

[0416] From this we can see that the error is small, indicating that the data are reasonable and reliable.

[0417] The heat balance table of the steam system with riser preheating and recovery is shown in Table 24.

[0418] Table 24 System heat balance table (based on 1t wet coal)

[0419]

[0420] The conversion based on 1t of coke is shown in Table 25.

[0421] Table 25 System heat balance table (based on 1t dry coke)

[0422]

[0423]

[0424] In Table 24 and Table 25, the heat carried away by the raw gas is the heat carried away by the raw gas when it leaves the riser heat exchanger.

[0425] As can be seen from Table 25, in the heat input side, the heat mainly comes from the raw coal gas. However, when the riser cover and the carbon removal hole cover are opened before the coke is pushed, the heat transfer from the flame gas in the riser to the riser wall is not high, but the intensity is large and the time is short. In the heat balance output side, although the total heat loss of the system is not high, accounting for only 2.60%, the lost heat comes from the heat transferred from the raw coal gas to the circulating water, accounting for 13.6% of the heat of the produced steam, indicating that the heat dissipation is still high.

[0426] From Table 25, the heat flow diagram of the riser raw gas waste heat recovery system can be drawn, such as Figure 5 shown.

[0427] From Table 25, we can see that:

[0428] The heat brought in by the raw gas is the heat brought in by the raw gas entering the riser heat exchanger, and it is also the heat brought out by the raw gas leaving the coke oven: Q h =937536kJ / t;

[0429] The heat carried away by the raw gas is the heat carried away by the raw gas leaving the riser heat exchanger: Q h ′=761829kJ / t.

[0430] The difference between the two is the heat ΔQ recovered from the raw gas after heat exchange in the riser heat exchanger. h :

[0431] ΔQ h =Q h -Q h ′=937536-761829=175707kJ / t.

[0432] That is, after the raw coal gas passes through the riser heat exchanger, the heat recovered is 175707 kJ / t, which reduces the (arithmetic) average temperature of the raw coal gas by 184.5℃ (see Table 1).

[0433] The ratio of heat released: △Q h / Q h =175707 / 937536=0.1874=18.74%

[0434] That is, 18.74% of the heat of the raw gas is recovered after heat exchange, so that the (arithmetic) average temperature of the raw gas is reduced by 184.5°C.

[0435] For spraying ammonia water, theoretically, it should be reduced by 18.74% accordingly, which can meet the requirement of reducing the raw gas temperature to 83℃.

[0436] For the horizontal tube primary cooler, theoretically, it should be reduced by 18.74% accordingly to meet the requirement of reducing the raw gas temperature to 20℃.

Claims

1. A method for evaluating the waste heat recovery efficiency of raw gas from a coke oven riser is used to reduce the amount of circulating ammonia water sprayed and the amount of cooling water used in a horizontal tube primary cooler, characterized in that: include: Calculate the amount of heat carried away by the raw gas when it leaves the riser heat exchanger, calculate the amount of heat carried away by the raw gas when it leaves the coke oven based on the ratio of the calibrated amount of heat carried away by the raw gas when it leaves the coke oven to the coking input heat of the coke oven and the real-time measured amount of heat carried away by the coke oven, calculate the difference between the amount of heat carried away by the raw gas in the riser raw gas waste heat recovery system and the amount of heat carried away by the raw gas when it leaves the riser heat exchanger, obtain the amount of heat recovered by the raw gas after heat exchange through the riser heat exchanger, calculate the ratio of the amount of heat recovered by the raw gas after heat exchange through the riser heat exchanger to the amount of heat carried away by the raw gas when it leaves the coke oven as the efficiency of the coke oven riser raw gas waste heat recovery; The coke oven riser raw gas waste heat recovery efficiency is the reduction in the amount of circulating ammonia water sprayed after the coke oven riser raw gas waste heat recovery device is running; The coke oven riser raw gas waste heat recovery efficiency is the reduction in the amount of cooling water used in the horizontal tube primary cooler after the coke oven riser raw gas waste heat recovery device is running; The heat brought into the raw gas waste heat recovery system by the raw gas in the riser, i.e., the heat brought out by the raw gas leaving the coke oven, Q h The heat Q brought out by the raw gas leaving the coke oven h It is calculated based on the ratio of the heat carried out by the calibrated raw gas leaving the coke oven to the coking input heat of the coke oven and the real-time measured coking input heat of the coke oven; Among them, the heat recovered after the raw gas passes through the riser heat exchanger includes the heat Q taken away by the raw gas leaving the riser heat exchanger. h "; The heat Q taken away by the raw gas from the riser heat exchanger h "It includes the following parts: (a) Tar takes away heat: Q1" = G JY (418.68+C JY t 1h ′), In the above formula: G JY = Tar amount obtained from 1000kg wet coal, G JY =26.38kg / t, C JY ——Average specific heat of tar, C JY =1.277+1.641×10 -3 t 1h ′=2.158kJ / kg℃; (b) Heat removed by benzene: Q2" = G B (431+C BQ t 1h ′), In the above formula: G B ——benzene production, G B =8.50kg / t, C BQ ——Average specific heat of crude benzene gas; C BQ =1.0258+1.2853×10 -3 t 1h ′; (c) Heat removed by ammonia: Q3" = G A C A t h , In the above formula: G A ——Ammonia production, G A =2.30kg / t, C A ——Ammonia at 0~t h Average specific heat between ℃, C A =2.501 kJ / kg℃; (d) Heat carried away by clean gas: In the above formula: C 1h ——After heat exchange at t 1h The average specific heat of coal gas at ′, C 1h =1.472kJ / m 3 ℃, C 2h ——After heat exchange at t 2h The average specific heat of coal gas at ′, C 2h =1.464kJ / m 3 °C, G MQ ——Gas production, r MQ ——Gas severity; (e) Heat brought by water vapor: Q5" = (G S +G SX )(2500.8+C SQ t 1h ′), C SQ ——After heat exchange at 0~t 1h Average specific heat of water vapor between ′℃, C SQ =1.987kJ / kg℃;G s ——Amount of water brought into the coal entering the furnace, G SX ——the amount of combined water brought into the coal entering the furnace; In the above formula, t 1h ′ is the average temperature of the raw gas in the first half of the coking period after heat exchange; t 2h ′——Average temperature of raw gas in the last half cycle after coking after heat exchange, t h ——Average temperature of raw coal gas during coking period after heat exchange; <h2 style=";text-align:left;direction:ltr">Q<h2 style=";text-align:left;direction:ltr"> h <h2 style=";text-align:left;direction:ltr"> "=Q1"+Q2"+Q3"+Q4"+Q5"; The raw gas recovers heat after heat exchange in the riser heat exchanger, that is, the heat brought out by the raw gas leaving the coke oven minus the heat Q brought out by the raw gas leaving the riser heat exchanger. h ", The ratio of the heat recovered from the raw gas after heat exchange in the riser heat exchanger to the heat taken out by the raw gas leaving the coke oven is calculated, and the waste heat recovery efficiency of the raw gas in the coke oven riser is obtained.

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