Anaerobic digestion process monitoring system and anaerobic digestion process monitoring method

Patent metadata

Field	Value
Publication number	US-12486484-B2
Application number	US-202219118364-A
Country	US
Kind code	B2
Filing date	Oct 11, 2022
Priority date	Oct 11, 2022
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

Provided is an anaerobic digestion process monitoring system for predicting a biogas production amount with high accuracy even when the activity of anaerobic microorganisms in a digestion tank changes. The anaerobic digestion process monitoring system includes: a first sensor which measures a feeding amount of organic waste into a digestion tank and outputs a measurement result as load data; a second sensor which measures a property of a fermented liquid inside the digestion tank and outputs a measurement result as fermented liquid property data; a preprocessing unit which calculates estimate activity index data indicating an anaerobic microorganism activity level from load data and fermented liquid property data, using a first estimation model; and a gas production amount prediction unit which calculates a biogas production amount prediction value from load data, fermented liquid property data, and estimate activity index data, using a second estimation model.

First claim

The invention claimed is:

1 . An anaerobic digestion process monitoring system which predicts a production amount of biogas to be produced from a fermented liquid obtained by acclimating anaerobic microorganisms inside a digestion tank with organic waste fed into the digestion tank, and monitors a state of an anaerobic digestion process, the anaerobic digestion process monitoring system comprising:
a first sensor which measures a feeding amount of the organic waste into the digestion tank and outputs a measurement result as load data; a second sensor which measures at least pH and an electrical conductivity of the fermented liquid inside the digestion tank, as a property, and outputs a measurement result; a process observation circuitry to accumulate the load data and at least the pH and the electrical conductivity; a preprocessing circuitry to calculate a concentration of an organic acid and a concentration of ammonia nitrogen from the load data, the pH, and the electrical conductivity, using a first estimation model constituted of at least a correlation formula between the concentration of the organic acid in the fermented liquid inside the digestion tank, and the load data and the pH, and a correlation formula between the concentration of the ammonia nitrogen in the fermented liquid inside the digestion tank, and the load data and the electrical conductivity, acquired before system introduction or in a given learning period after system introduction; and a gas production amount prediction circuitry to predict a biogas production amount prediction value, from at least the load data, the pH, the electrical conductivity, and the concentration of the organic acid and the concentration of the ammonia nitrogen calculated by the preprocessing circuitry, using a second estimation model constituted of at least a correlation formula between the biogas production amount, and the load data, the pH, and the concentration of the organic acid in the fermented liquid inside the digestion tank, and a correlation formula between the biogas production amount, and the load data, the electrical conductivity, and the concentration of the ammonia nitrogen in the fermented liquid inside the digestion tank, acquired before system introduction or in a given learning period after system introduction, wherein the state of the anaerobic digestion process is monitored using the concentration of the organic acid and the concentration of the ammonia nitrogen calculated by the preprocessing circuitry, and the biogas production amount prediction value predicted by the gas production amount prediction circuitry.

2 . The anaerobic digestion process monitoring system according to claim 1 , further comprising:
a third sensor which measures the production amount of the biogas produced in the digestion tank, and outputs a measurement result as a biogas production amount actual measurement value; and a process monitoring circuitry to calculate an error ratio from the biogas production amount actual measurement value and the biogas production amount prediction value.

3 . The anaerobic digestion process monitoring system according to claim 2 , wherein
the first sensor measures the feeding amount of the organic waste at predetermined measurement time intervals and outputs the feeding amount as the load data, the second sensor measures the property of the fermented liquid at the measurement time intervals at times when the first sensor measures the feeding amount of the organic waste, and outputs a measurement result, the third sensor measures the production amount of the biogas produced in the digestion tank, at the measurement time intervals at the times when the first sensor measures the feeding amount of the organic waste, and outputs the production amount as the biogas production amount actual measurement value, the process observation circuitry accumulates the load data, the pH, and the electrical conductivity as time-series data at the measurement time intervals, and where one of the times when the first sensor measures the feeding amount of the organic waste is defined as a specific time, the preprocessing circuitry calculates the concentration of the organic acid and the concentration of the ammonia nitrogen at the specific time, from the load data measured at the specific time and the pH and the electrical conductivity measured at the specific time, and accumulates the concentration of the organic acid and the concentration of the ammonia nitrogen at each time as time-series data at the measurement time intervals, and the gas production amount prediction circuitry calculates the biogas production amount prediction value at the specific time, from the load data measured at the specific time, the pH and the electrical conductivity measured at the specific time, and the concentration of the organic acid and the concentration of the ammonia nitrogen at the specific time.

4 . The anaerobic digestion process monitoring system according to claim 3 , wherein
in a case where a value of the error ratio is within a predetermined error ratio normal range, the biogas production amount actual measurement value is within a predetermined gas production amount normal range, and the concentration of the organic acid and the concentration of the ammonia nitrogen are within a predetermined activity index normal range, the process monitoring circuitry calculates update correlation data which is correlation data between the biogas production amount actual measurement value, and the load data, the pH, the electrical conductivity, the concentration of the organic acid, and the concentration of the ammonia nitrogen, and outputs the update correlation data to the gas production amount prediction circuitry, and the gas production amount prediction circuitry updates a calculation formula for the second estimation model, using the update correlation data.

5 . The anaerobic digestion process monitoring system according to claim 4 , wherein
the gas production amount prediction circuitry outputs the concentration of the organic acid and the concentration of the ammonia nitrogen to the process monitoring circuitry, and in a case where a value of the error ratio is outside the predetermined error ratio normal range, the biogas production amount actual measurement value is outside the predetermined gas production amount normal range, and the concentration of the organic acid and the concentration of the ammonia nitrogen are within the predetermined activity index normal range, the process monitoring circuitry outputs a signal for recommending maintenance of the third sensor.

6 . The anaerobic digestion process monitoring system according to claim 4 , wherein
in a case where a value of the error ratio is outside the predetermined error ratio normal range and the biogas production amount actual measurement value is within the predetermined gas production amount normal range, the process monitoring circuitry outputs a signal for recommending maintenance of the first sensor and the second sensor.

7 . The anaerobic digestion process monitoring system according to claim 4 , wherein
the gas production amount prediction circuitry outputs the concentration of the organic acid and the concentration of the ammonia nitrogen to the process monitoring circuitry, and in a case where a value of the error ratio is within the predetermined error ratio normal range, the biogas production amount actual measurement value is outside the predetermined gas production amount normal range, and the concentration of the organic acid and the concentration of the ammonia nitrogen are outside the predetermined activity index normal range, the process monitoring circuitry outputs a signal for recommending stop of a biogas production system and re

Assignees

• Mitsubishi Electric Corp

Inventors

• Aketagawa Kyohei
• Katsumata Noriaki

Classifications

• C12M41/48

  Automatic or computerized control (automatic analysis G01N35/00) · CPC title

• C12M41/44

  of volume or liquid level · CPC title

• C12M41/28

  of redox potential · CPC title

• C12M21/04

  for producing gas, e.g. biogas (digesters for manure with production of biogas A01C3/028, biological treatment of water, waste water or sewage C02F3/00, C02F11/02, preparation of natural gas or syngas C10L3/06, C10L3/10) · CPC title

• B09B2101/70

  Kitchen refuse; Food waste · CPC title