1. A mixed gas heat value metering method is characterized by comprising the following steps:

signals of a blast furnace gas flow meter installed on an original blast furnace gas pipeline before gas mixing, a coke furnace gas flow meter installed on the coke furnace gas pipeline and a converter gas flow meter installed on the converter gas pipeline are respectively connected to a PLC (programmable logic controller) or DCS (distributed control system);

respectively setting a theoretical heat value of blast furnace gas, a theoretical heat value of coke oven gas and a theoretical heat value of converter gas in the PLC or DCS system, and calculating the theoretical heat values of the mixed gas through a formula according to the proportion of the blast furnace gas, the coke oven gas and the converter gas in the mixed gas;

the calculation method is as follows:

blast furnace before mixingThe blast furnace gas flow measured by the gas pipeline flow meter is Q_BIn units of Nm³H; the coke oven gas flow measured by the coke oven gas pipeline flow meter is Q_CIn units of Nm³H; the converter gas pipeline flow meter measures the converter gas flow as Q_LIn units of Nm³H; blast furnace gas heat value of H_BIn kcal/Nm³(ii) a The heat value of the coke oven gas is H_CIn kcal/Nm³(ii) a The calorific value of the converter gas is H_Lkcal/Nm 3; mixed gas having a calorific value of H_{Mixing of}In kcal/Nm³；

The PLC or DCS system can calculate the mixed gas heat value H through the following formula_{Mixing of}：

2. The mixed gas calorific value metering method of claim 1, wherein the blast furnace gas flow meter, the coke oven gas flow meter and the converter gas flow meter are compensated by temperature and pressure.

3. The mixed gas heat value metering method of claim 1, wherein the theoretical heat value of the blast furnace gas is 850-950 kcal/Nm³The heat value of the coke oven gas is 3900-4400 kcal/Nm³The heat value of the converter gas is 1800-2200 kcal/Nm³(ii) a Analyzing and obtaining the average value of the gas heat values as the theoretical heat value of each gas according to the actual sampling and accumulation data of the gas heat values of each daily gas cabinet, namely the blast furnace gas H_BIs 800kcal/Nm³Coke oven gas H_C4000kcal/Nm³Converter gas H_LIs 1800kcal/Nm³And setting the data to a PLC or DCS system.

4. The mixed gas calorific value metering method of claim 1, wherein the blast furnace gas is from a blast furnace gas holder, the coke furnace gas is from a coke furnace gas holder, and the converter gas is from a converter gas holder before the gas is mixed.

Background

The byproduct gas of the iron and steel enterprises mainly comprises blast furnace gas, coke oven gas and converter gas, and the gas has different and greatly different heat values. In order to save energy, improve benefit and protect environment, the blast furnace gas is mainly used for power generation at present, and converter gas needs to be fully utilized. Because the calorific value of the converter gas is lower than that of a steel rolling user, three kinds of gas need to be mixed according to a certain volume ratio to form mixed gas to be supplied to the user, and the mixing ratio can be controlled only by knowing the calorific value of the mixed gas after mixing.

The existing mixed gas heat value metering technology comprises the following steps:

the patent technology of 'a mixed gas heat value monitoring system and method' (application number CN202010869154.X publication (No) CN112098458A) by Chongqing Saidi thermal environment-friendly engineering technology Limited company and Zhongjie Saidi technology research center Limited company relates to a mixed gas heat value monitoring system and method, and belongs to the technical field of steel energy production management. The system comprises a gas mixing station parameter monitoring module, a mixed gas user monitoring module, a monitoring information transmission module, a gas pipe network flow analysis module and a mixed gas heat value monitoring terminal; the gas mixing station parameter monitoring module and the mixed gas user monitoring module are connected with the gas pipe network flow analysis module and the mixed gas heat value monitoring terminal through the monitoring information transmission module; the gas pipe network flow analysis module analyzes and calculates the received monitoring data, and integrates the real-time monitoring data and the simulation calculation result to be visually displayed on the mixed gas heat value monitoring terminal. The invention can calculate the heat value of each mixed gas user in real time, and realize the heat value monitoring of the whole mixed gas system.

(application No. CN201720312423.6 publication (announcement) No. CN206804566U) patent technology relates to the field of gas analysis and measurement, in particular to a combustion type heat value instrument with a specific gravity measurement unit, which comprises a shell, a furnace body, a combustion chamber, a fuel gas supply pipeline, a combustion air pipeline, a variable-frequency combustion fan and a control unit, wherein the combustion chamber is sequentially provided with: the device comprises a thermopile temperature sensor, a heat exchanger and a burner, wherein the top of a combustion chamber is provided with a combustion waste gas discharge port; a variable-frequency combustion-supporting fan; and the specific gravity measuring unit is positioned on the fuel gas supply pipeline, and the outlet side of the specific gravity measuring unit is connected with the fuel gas inlet of the mixer unit. The invention can realize the heat value analysis of various industrial combustible gases with different components and proportions; the application range is wide, and all fuel gases can be covered; the PLC is adopted to control the variable-frequency combustion fan, so that the output of the combustion air quantity is constant, and the precision of repeated measurement is improved.

The combustion type fuel gas heat value measuring method of the patent technology of Zhangping 'combustion type fuel gas heat value measuring method and heat value instrument' (application No. CN200610000942.5 publication (Notification) No. CN1800848A) adopts a fuel gas connecting device and a combustion-supporting air conveying device, a certain amount of fuel gas and a certain amount of combustion-supporting air are input into a combustion furnace cylinder to be completely combusted to generate flue gas, and the heat value of the fuel gas is calculated by measuring the residual oxygen content in the flue gas; the invention detects the residual oxygen content in the combustion product smoke by adopting the principle of gas combustion chemical reaction, when the method and the heat value instrument are used for detection, the detection precision is not influenced by the change of the environmental temperature, and no hysteresis phenomenon exists in the detection process, so the result measured by the method and the heat value instrument has high precision, the sensitivity of the heat value instrument is high, the heat value instrument does not need to be arranged in the environment of constant temperature and constant humidity air conditioning equipment, and the technical measure for reducing the large hysteresis of the furnace temperature change does not need to be added, so the heat value instrument has stable operation, small maintenance workload and low cost.

There are problems and deficiencies:

the method includes the steps that only gas components at the outlet of the mixing station are detected, the hydraulic flow characteristics of the gas pipe network are utilized to perform pipe network flow online simulation calculation, the heat value of each mixed gas user is obtained through real-time calculation, and the heat value monitoring of the whole mixed gas system is achieved. The simulation calculation of the mixed gas pipe network is based on a pipeline hydraulic calculation theoretical equation, a mixed gas pipe network hydraulic simulation calculation model is established according to the configuration conditions of the mixed gas pipe network, the heat value result of each mixed gas user is obtained by inputting the real-time monitoring data of the flow, the pressure, the temperature and the gas components of the outlet gas of the mixing station and the flow, the pressure and the temperature of each mixed gas user, the establishment and the calculation of the whole model are complex, an analyzer is required to be installed at the outlet of the mixing station to detect the gas components at the outlet of the mixing station, and the equipment investment cost is high; secondly, the patent technology provides a combustion type heat value instrument, and secondly, a formula is deduced according to a heat balance principle to calculate the heat value of the fuel gas; and thirdly, calculating the heat value of the fuel gas by measuring the residual oxygen content in the flue gas. The patent technology needs to add equipment to measure the calorific value of the mixed gas, and does not meet the requirements of cost reduction and efficiency improvement under the condition of integral micro-profit of the steel industry at present.

Disclosure of Invention

The invention aims to provide a mixed gas heat value metering method, which is characterized in that on the basis of not increasing detection equipment, the heat value of the mixed gas is obtained by a theoretical calculation method, the mixing proportion of three kinds of gas is controlled to meet the requirements of steel rolling users, and simultaneously, converter gas is fully utilized.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention relates to a mixed gas heat value metering method, which comprises the following steps:

signals of a blast furnace gas flow meter installed on an original blast furnace gas pipeline before gas mixing, a coke furnace gas flow meter installed on the coke furnace gas pipeline and a converter gas flow meter installed on the converter gas pipeline are respectively connected to a PLC (programmable logic controller) or DCS (distributed control system);

respectively setting a theoretical heat value of blast furnace gas, a theoretical heat value of coke oven gas and a theoretical heat value of converter gas in the PLC or DCS system, and calculating the theoretical heat values of the mixed gas through a formula according to the proportion of the blast furnace gas, the coke oven gas and the converter gas in the mixed gas;

the calculation method is as follows:

the blast furnace gas flow measured by the blast furnace gas pipeline flow instrument before mixing is Q_BIn units of Nm³H; the coke oven gas flow measured by the coke oven gas pipeline flow meter is Q_CIn units of Nm³H; the converter gas pipeline flow meter measures the converter gas flow as Q_LIn units of Nm³H; blast furnace gas heat value of H_BIn kcal/Nm³(ii) a The heat value of the coke oven gas is H_CIn kcal/Nm³(ii) a The calorific value of the converter gas is H_LIn kcal/Nm³(ii) a Mixed gas having a calorific value of H_{Mixing of}In kcal/Nm³；

The PLC or DCS system can calculate the mixed gas heat value H through the following formula_{Mixing of}：

Furthermore, the blast furnace gas flow meter, the coke oven gas flow meter and the converter gas flow meter adopt temperature and pressure compensation for flow measurement.

Further, the theoretical calorific value of the blast furnace gas is 850-950 kcal/Nm³The heat value of the coke oven gas is 3900-4400 kcal/Nm³The heat value of the converter gas is 1800-2200 kcal/Nm³(ii) a Analyzing and obtaining the average value of the gas heat values as the theoretical heat value of each gas according to the actual sampling and accumulation data of the gas heat values of each daily gas cabinet, namely the blast furnace gas H_BIs 800kcal/Nm³Coke oven gas H_C4000kcal/Nm³Converter gas H_LIs 1800kcal/Nm³And setting the data to a PLC or DCS system.

Further, the blast furnace gas is from a blast furnace gas cabinet, the coke oven gas is from a coke oven gas cabinet, and the converter gas is from a converter gas cabinet before the gas is mixed.

Compared with the prior art, the invention has the beneficial technical effects that:

the invention can solve the problem of measuring the heat value of the existing mixed gas without adding equipment, realizes the full utilization of converter gas and meets the heat value requirement of steel rolling users, can effectively guide production, maximally reduces the waste of gas diffusion, saves energy, improves the benefit and protects the environment.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is a schematic diagram of the main structure of the mixed gas heat value metering method of the present invention;

description of reference numerals: 1-blast furnace gas flow measuring instrument, 2-coke furnace gas flow measuring instrument, 3-converter gas flow measuring instrument, 4-blast furnace gas cabinet, 5-coke furnace gas cabinet, 6-converter gas cabinet, 7-user, 8-PLC or DCS system.

Detailed Description

As shown in figure 1, the main structure of the mixed gas heat value metering method comprises blast furnace coalThe system comprises a gas flow measuring instrument 1, a coke oven gas flow measuring instrument 2, a converter gas flow measuring instrument 3, a blast furnace gas cabinet 4, a coke oven gas cabinet 5, a converter gas cabinet 6, a user 7 and a PLC or DCS system 8; the blast furnace gas flow measuring instrument 1 is a measuring instrument which is arranged on a blast furnace gas pipeline before gas is mixed and is used for measuring the flow of blast furnace gas; the coke oven gas flow meter 2 is a meter which is arranged on a coke oven gas pipeline before gas mixing and is used for measuring the flow of the coke oven gas; the converter gas flow measuring instrument 3 is a measuring instrument which is arranged on a gas pipeline of the converter before gas mixing and is used for measuring the gas flow of the converter; the blast furnace gas flow meter 1, the coke oven gas flow meter 2 and the converter gas flow meter 3 are all compensated by adopting flow temperature and pressure, and signals are respectively connected to a PLC (programmable logic controller) or DCS (distributed control system) 8. The blast furnace gas cabinet 4 distributes blast furnace gas to the mixed gas station; the coke oven gas cabinet 5 delivers coke oven gas to the mixed gas station; the converter gas cabinet 6 delivers converter gas to the mixed gas station. Setting the average value of the actual gas heat values of the gas cabinets 4, 5 and 6 as the theoretical heat values of the gas into the PLC or DCS system 8, wherein the blast furnace gas H is selected from the gas cabinets 4, 5 and 6_BSet at 800kcal/Nm³Coke oven gas H_CSet to 4000kcal/Nm³Converter gas H_LSet to 1800kcal/Nm³. The PLC or DCS system 8 calculates the mixed gas heat value H according to the following formula_{Mixing of}：

Wherein: q_BIs the blast furnace gas flow rate, Q_CIs the flow rate Q of coke oven gas_LIs the converter gas flow rate in Nm³/h；H_BIs the heat value of blast furnace gas, H_CIs the heat value H of coke oven gas_LIs the calorific value H of converter gas_{Mixing of}Is the heat value of the mixed gas and has the unit of kcal/Nm³。

Further, the converter coal is preferentially added in the control of the gas mixing operationGas, under the premise of ensuring that the converter gas is fully utilized, in order to avoid the blast furnace gas from diffusing, the surplus blast furnace gas generated by power generation is completely distributed into a mixed gas system; finally, according to the user 7, the mixed gas is 2000kcal/Nm³The mixing proportion of the coke oven gas is adjusted according to the heat value requirement, the consumption of the mixed gas and the addition of the converter gas and the blast furnace gas, and the mixed distribution of the mixed gas is completed.

On the basis of the existing installation of flow metering instrument equipment, the invention does not need to add detection equipment such as a heat value instrument, a component analyzer and the like, can solve the problem of measuring the heat value of the existing mixed gas, realizes the full utilization of converter gas and meets the heat value requirement of steel rolling users, can effectively guide production, maximally reduces the waste of gas diffusion, saves energy, improves benefit and protects environment. The device has the characteristics of simple structure, high stability and high reliability, and can be popularized and applied to theoretical measurement of the calorific value of the mixed gas of each gas mixing station and used as the basis for the mixing control operation of each gas according to the requirements.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.