JPH0645617Y2 - Reducing agent control device for denitration equipment - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration device for an internal combustion engine that denitrates exhaust gas from the internal combustion engine by a selective catalytic reduction method, and particularly controls the amount of reducing agent supplied according to the required denitration rate. The present invention relates to a reducing agent control device of a denitration device that is made possible.

[0002]

2. Description of the Related Art N contained in exhaust gas from an internal combustion engine
A selective catalytic reduction method is known as a method for treating Ox. In this method, ammonia gas, ammonia water, urea water, etc. are used as the reducing agent. In order to obtain the required denitration rate, conventionally, the amount of exhaust gas and NOx concentration have been measured to determine the amount of reducing agent.

[0003]

The NOx concentration meter for measuring the NOx concentration in exhaust gas is an expensive device, and there has been a demand to avoid using such a device for cost reduction. The present invention has been made in response to the above-mentioned problems, and an object thereof is to provide a reducing agent control device for a denitration device capable of controlling the amount of reducing agent with a simple and inexpensive structure.

[0004]

A reducing agent control device for a denitration device according to the present invention processes a reducing agent supply unit for adding a reducing agent to exhaust gas from an internal combustion engine, and an exhaust gas added with the reducing agent. In a reducing agent control device provided in a denitration device having a denitration reaction part, a setting part for setting a NO _x value of exhaust gas at the outlet of the denitration reaction part, an engine output sensor, a supply air temperature sensor, and an atmospheric temperature. Sensor, atmospheric relative humidity sensor, atmospheric pressure sensor, fuel flow rate sensor,
A NO _x value is calculated based on signals from the engine output sensor, the supply air temperature sensor, the atmospheric temperature sensor, the atmospheric relative humidity sensor, and the atmospheric pressure sensor, and the calculated NO _x value and the signal from the fuel flow rate sensor Based on the calculated NO _x amount of the exhaust gas discharged from the internal combustion engine, and based on the calculated NO _x amount and the NO _x value set in the setting unit, the reducing agent amount added to the exhaust gas is calculated. And a computing unit that outputs a control signal to the reducing agent supply unit.

[0005]

[Function] Each sensor measures ambient conditions and engine conditions.
The calculation unit calculates the amount of NOx emitted by the internal combustion engine based on the signals from the sensors. Further, the calculation unit calculates the required amount of reducing agent based on the target NOx value preset in the setting unit and the calculated NOx amount, and controls the reducing agent supply unit based on this value.

[0006]

1 shows an embodiment of the present invention. The diesel engine 1 as an internal combustion engine is adapted to discharge exhaust gas containing NOx through the flue 2. A reducing agent sprayer 3 is provided in the middle of the flue 2, and a denitration reactor 5 is provided between the reducing agent sprayer 3 and the outlet 4. A reducing agent is supplied from the reducing agent supply unit 6 to the reducing agent sprayer 3. The reducing agent supply unit 6 has a reducing agent storage / supply unit 7 and a control valve 8. If a control signal is applied to the control valve 8 to adjust the opening degree of the valve, the reducing agent sprayer 3 is operated. The amount of the reducing agent injected can be adjusted arbitrarily.

In or near the diesel engine 1,
The following six types of sensors are provided. That is,
An engine output sensor W (hereinafter, referred to as sensor W) that detects an engine output W of a diesel engine, and a supply air temperature sensor T ₃ (hereinafter, referred to as sensor T ₃ ) that detects a supply air temperature T ₃ of the diesel engine. fuel flow sensor Q detects a fuel flow rate Q of the diesel engine (hereinafter, referred to as a sensor Q.), atmospheric temperature sensor T ₀ for detecting the atmospheric temperature T _{0 (hereinafter,} referred to as a sensor T _0.), relative atmospheric humidity Atmospheric relative humidity sensor H (hereinafter, referred to as sensor H) for detecting H, atmospheric pressure P ₀
Is an atmospheric pressure sensor P ₀ (hereinafter, referred to as sensor P ₀ ). Then, the detection signals from these respective sensors are input to the arithmetic unit of the computer 10 via the A / D converter 9.

Generally, the NOx value of a diesel engine becomes a certain value by converting it using the measured values of the following ambient conditions and engine conditions. This is the standard NOx value (N
Ox ₀ ). Measured values are (1) engine output W, (2)
Air supply temperature T ₃ , (3) atmospheric temperature T ₀ . (4) Atmospheric relative humidity H, (5) Atmospheric pressure P ₀ . Therefore, the reference NOx
The value can be expressed by the following equation. NOxo = f ₀ (W, T ₃ , T ₀ , H, P ₀ ) (A) Further, (6) By measuring the fuel flow rate Q, the amount of NOx discharged can be expressed by the following equation. . NOxv = f ₁ (f ₀ , Q) (B) From the above, the reference NOx value (NOx) of the engine is calculated in advance.
If o) is obtained, the NOx value and N at a certain engine output can be obtained by measuring the measurement values (1) to (6).
The amount of Ox can be estimated.

In the present embodiment, the NOx concentration for each load of the diesel engine 1 is actually measured, and the NOx concentration (NOx value) is set in the setting section of the computer 10 in advance.
It is stored as o). Then, the arithmetic unit can estimate the actual NOx value from the measured values (1) to (6) based on the above-described equations (A) and (B), and further estimate the NOx amount (NOxv) in the engine output at that time. Is configured.

In addition, a target NOx value at the outlet 4 of the denitration reactor 5 is set in the setting section of the computer 10. The computing unit of the computer 10 is
It is configured to calculate the amount of reducing agent to be supplied based on the estimated NOx amount and the target NOx value of the setting unit. That is, according to this example, the amount of reducing agent can be calculated according to the required denitration rate.

Then, the computing unit of the computer 10 gives a control signal according to the calculated amount of reducing agent to the flow rate controller 12 via the D / A converter 11, and controls the control valve 8 of the reducing agent supply unit. Is configured to control.

According to the above configuration, the above (1)-
The NOx amount can be estimated with high accuracy from the measured values of the atmospheric condition and the engine condition of (6), and the supply amount of the reducing agent can be controlled according to the required denitration rate.

FIG. 2 is a graph showing the effect when the reducing agent control device of the denitration device according to this embodiment is used.
The x-value and the time-dependent change in the difference (η−q) between the actually measured denitration rate and the target denitration rate are shown. As can be seen, the estimated value shown in O 2 _13% conditions (○ mark) is, found (● mark) the measured values in terms of O ₂ 13% condition (△
(Mark) matches very well. Therefore, the difference (η−q) between the actually measured denitration rate and the target denitration rate is constant around 0 regardless of changes in ambient conditions due to seasonal changes.

The above-mentioned six types of sensors W, T ₃ , T ₀ ,
H, P ₀ , and Q are usually provided in a stationary medium-sized diesel engine used for power generation or the like, and need to be provided again when constructing the reducing agent control device of the denitration device as in this embodiment. Often there is no. Therefore, expensive NO
It is possible to construct a highly effective reducing agent control device for a denitration device by utilizing existing equipment without providing an x-densitometer.

[0015]

According to the present invention, in addition to the signals from the engine output sensor, the supply air temperature sensor, and the atmospheric relative humidity sensor, the signals from the atmospheric temperature sensor and the atmospheric pressure sensor are also used to achieve highly accurate NO determination. _{The x} value is calculated. Then, the NO _x amount of the exhaust gas discharged from the internal combustion engine is calculated based on the calculated NO _x value and the signal from the fuel flow rate sensor, and the required reducing agent amount is determined based on this. Therefore, according to the present invention, a highly accurate NO _x value can be obtained as compared with the conventional device, and expensive equipment such as a supercharged turbine tachometer is not necessary for knowing the amount of exhaust gas. Effective denitration of exhaust gas can be realized at low cost by controlling a high reducing agent amount.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing an effect of the embodiment.

[Explanation of symbols]

1 Diesel engine as internal combustion engine, 4 outlets, 5
Denitration reactor as denitration reaction part, 6 reducing agent supply part, 1
A computer having a 0 setting unit and a calculation unit, a W engine output sensor, a T ₃ supply air temperature sensor, a T ₀ atmospheric temperature sensor, a H atmospheric relative humidity sensor, a P ₀ atmospheric pressure sensor, Q
Fuel flow sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hisao Tanabe 125-1 Nishishinmachi, Ota City, Gunma Niigata Iron Works Co., Ltd. )

Claims (1)

[Scope of utility model registration request] 1. A reducing agent control device provided in a denitration device having a reducing agent supply section for adding a reducing agent to exhaust gas from an internal combustion engine and a denitration reaction section for processing the reducing agent-added exhaust gas, a setting unit for setting a NO _x value of the exhaust gas at the outlet of the denitration reaction section, and the engine output sensors, a supply air temperature sensor, and the atmospheric temperature sensor, a relative atmospheric humidity sensor, and atmospheric pressure sensors, fuel flow sensors A NO _x value based on signals from the engine output sensor, the supply air temperature sensor, the atmospheric temperature sensor, the atmospheric relative humidity sensor and the atmospheric pressure sensor, and the calculated NO _x value and the fuel flow rate sensor N that of calculating the amount of NO _x in the exhaust gas discharged from the internal combustion engine based on the signal, the calculated
Based on the O _x amount and the NO _x value set in the setting unit,
A reducing agent control device for a denitration device, comprising: a calculating portion that calculates the amount of reducing agent added to exhaust gas and outputs a control signal to the reducing agent supply portion.