JPS60232299A - Temperature control apparatus of digestion tank - Google Patents

Abstract

PURPOSE:To prevent the loss of energy by stably performing operation with good efficiency, by controlling digestion temp. so that the generation amount of digestion gas per a charged org. substance becomes constant. CONSTITUTION:The gas generation amount operator of a charged org. substance calculates the necessary generation amount of gas per the amount of the org. substance in charged sludge on the basis of the sludge flow amount Q(m<3>/h) of charged sludge, the concn. LIN(kg/kg) of the org. substance in said sludge and the flow amount F(Nm<3>/kg) of digestion gas generated from a digestion tank according to formula I [wherein (r) is the specific gravity (kg/m<3>) of charged sludge]. A digestion temp. set value T'( deg.C) is operated from the operated value R by a gas generation amount regulator according to formula II (wherein G is the gain of the regulator and R' is an R-set value) and a digestion temp. is set and controlled to an optimum state from the amount of the org. substance in charged sludge and the generation state of the digestion gas from the digestion tank to operate the digestion tank.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a temperature control device for a digestion tank in a sewage sludge treatment system or the like.

[Prior art]

FIG. 5 is a block diagram showing a conventional temperature control device for a digestion tank. In the figure, (1) is the digestion tank, (2) is the sludge supply pipe to the digestion tank, (3) is the input sludge thermometer that measures the temperature of the sludge flowing inside the sludge supply pipe (2), and (4) is the An input sludge flow meter that measures the flow rate of sludge flowing in the sludge supply pipe (2), (5) is the measured value of the input sludge thermometer (3),
A Toguchi thermal calorific value calculator (5) calculates the required heating calorific value from the measurement value of the input sludge flowmeter (4) and the digestion temperature setting value, and (5) is the required heating calorific value calculated by the Toguchi thermal calorific value calculator (5). Fuel supply valve (9) to the heating boiler (8) according to the amount of heat
This is a feedforward calculator that sets the standard opening degree. (7) adds the setting value of this feedforward calculator (6) and the output signal of the boiler hot water temperature detector aO to control the opening degree of the fuel supply valve (9) to the heating boiler (8). The adder that is used is the digestion temperature detector (6) of the digestion tank (1).
) Three-way switching valve (2) depending on the difference between the output signal and the set value
α→ is a circulation sludge heat exchanger that heats circulating sludge with hot water from the heating boiler (8).

A conventional digester temperature control device is configured as described above.
A heating calorific value calculator (5) is installed to calculate the necessary heating calorific value from the measured values of the amount of sludge input to the digestion tank (1) and the temperature of the input sludge, and the digestion temperature set value, and this output is used to calculate the required heating calorific value from the fuel supply valve. (9)
The opening degree of the fuel supply valve (9) is controlled by correcting this value with the output signal from the boiler temperature controller mortar 1.

In this manner, the conventional temperature control device sets the digestion temperature in advance and controls the digestion temperature to be maintained even if the flow rate of sludge changes. However, the digestion temperature setting value is not always maintained constant, and the organic matter concentration of the input sludge
Orui needs to change the digestion temperature depending on the state of digestion in the digestion tank.

Furthermore, if the input sludge flow rate increases or decreases beyond a certain range, it is necessary to change the digestion temperature setting value to operate efficiently. Therefore, in the past, methods such as manually changing the digestion temperature set value or setting the digestion temperature set value on the safe side based on the load based on the maximum input amount of digested sludge have been used.

As described above, the means for setting the digestion temperature set value of conventional equipment is not only complicated to manually change the set value, but also difficult to operate stably and efficiently, and it consumes energy by operating at a higher temperature than necessary. There were drawbacks such as losses.

[Summary of the invention]

The present invention was made for the purpose of eliminating such drawbacks.
Means for measuring the amount of input sludge, the concentration of organic matter in the sludge, and the amount of digestion gas generated from the digestion tank, and means for calculating the amount of digestion gas generated per amount of organic matter in the input sludge from each measurement value, and the calculation. The digestion temperature control device, which consists of a means for controlling the digestion temperature so that it reaches the optimal digestion temperature setting value determined from the results, always maintains the optimal digestion temperature, operates the digester efficiently, and prevents energy loss. An object of the present invention is to provide a digester temperature control device.

[Embodiments of the invention]

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, (3) is a flowmeter that measures the sludge flow rate in the sludge supply pipe (2), α→ is a device for measuring the organic matter concentration of sludge, and (to) is a flowmeter for the digestion gas generated from the digestion tank (1). From these measured values, input organic gas generation amount calculator αη
The amount of digestion gas generated per the amount of organic matter in the input sludge is calculated. (1) is a gas generation amount controller that provides the optimal digestion temperature setting value according to the difference between the calculated output value and the preset gas generation amount per organic amount of input sludge. .

<11) is the temperature of the digestion tank (1) detected by the digestion temperature detector (6).
Digestion temperature control that adjusts the hot water flow rate of the heating boiler (3) by the opening of the three-way switching valve (4) so that the digestion temperature of α◆ is a heat exchanger for heating the digestion tank with the hot water of the heating boiler (3), and sb, 01 is the temperature of the heating boiler (3) in order to maintain the hot water of the heating boiler at a constant temperature. The temperature is detected by the temperature sensor ◇0, and the boiler temperature controller adjusts the opening degree of the fuel supply valve (9).

The temperature control device for the digestion tank of the present invention is configured as described above, and the gas generation amount calculator ◇η of the input organic matter is calculated based on the sludge flow rate of the input sludge, the organic matter concentration of the sludge, and the input organic matter gas generation amount calculator ◇η.
Calculate the amount of gas generated per required amount of organic matter in the input sludge based on the flow rate of the digestion gas generated from the sludge using the following formula.

However, R: amount of gas generated per amount of organic matter input (N-/9
) F: Digestion gas generation amount (N, ?/9) γ: Specific gravity of input sludge (kg/, /) Q: Flow rate of input sludge (ty//h) LIN: Concentration of organic matter in input sludge (kg/kII) From the above-calculated amount of gas generated per amount of input organic matter, the set value of the digestion temperature is calculated using the gas generation amount controller 0→ according to the following equation.

T*= G (R*-R) ... ■However, G: Set the controller gain and the digestion temperature, and perform the digestion based on the amount of organic matter in the input sludge and the state of the digestion gas in the digestion tank (1). The digestion tank (1) is operated while controlling the temperature to an optimum state.

At that time, the digestion temperature is determined by the relationship between the amount of sludge input and the volume of the digestion tank (1), the number of days for digestion, which is the number of days the sludge stays in the tank (1), and the amount of digestion gas generated within that number of days. becomes the temperature. According to Fain and MOOre, the digestion temperature and the number of days required to finally produce 90% of the digestion gas (
The relationship between digester volume/input sludge amount is as shown in Figure 2. According to FIG. 2, it is clear that there are appropriate digestion temperature ranges in the high temperature range of 40°C to 55°C and the intermediate temperature range of 30°C to 67°C. Furthermore, if the digestion temperature is high in these temperature ranges, the number of days for digestion will be shortened. In other words, the decomposition speed becomes faster. Therefore, when the amount of input sludge and the organic matter concentration of the sludge are low, the digestion period can be extended, so the operation is performed at a digestion temperature in the intermediate temperature range, and in the opposite case, the operation is performed at a digestion temperature in the high temperature range.

During operation of the digestion tank (1), the appropriateness of the digestion temperature, the quality of the digestion rate, etc. can be easily determined by detecting and examining the amount of gas generated per amount of organic matter in the input sludge.

The relationship between the amount of digestion gas generated per amount of organic matter input at a predetermined digestion temperature and the number of days for digestion is as shown in FIG. Therefore, when the predetermined number of days for digestion has passed, if the amount of digestive gas generated per input organic matter is lower than the value shown in Figure 3 for a predetermined digestion temperature, either the amount of input organic matter is too large or the digestion temperature is low, so the organic matter is This means that the gas is not sufficiently gasified.

As a result, digestion becomes insufficient, and in extreme cases, organic matter accumulates in the digestion tank (1), causing problems in operation. On the other hand, if the amount of digestion gas generated is larger than the value shown in Figure 6, it means that the amount of organic matter input is small, or the digestion temperature is set or is higher than necessary, resulting in energy loss. becomes larger.

According to the temperature control device of the present invention, the optimum digestion temperature is maintained for the amount of input organic matter, so that the above-mentioned inconveniences can be avoided.

In the above embodiment, the digestion temperature is controlled to be corrected in response to changes in the amount of input organic matter, but in another embodiment, as shown in FIG. (Foundation), and from the measured concentration, the calculation unit 03 calculates the amount of input organic matter using a linear regression equation, and from the calculated amount of input organic matter, the gas generation amount calculation unit α calculates the amount of digestive gas generated, From the calculated output value, the gas generation amount controller α
The digestion temperature set value is obtained from the barrel, and then the output value of the digestion temperature set value is limited to a preset upper and lower limit range by a calculator (four forces).Then, the digester temperature is detected by the calculator 09. The digestion temperature of the digestion tank (1) detected by the vessel (6);
Calculator 01) sets the digestion temperature set value in stages so that the difference between the set value and the set value of the digestion temperature, which is limited within the range of upper and lower limits, remains within a predetermined period of time during which the temperature changes per unit time. The digestion temperature regulator α changes the temperature of the digestion tank (1) accordingly.

Therefore, even if there is a sudden change in the digestion temperature, such as a shift from a high temperature range (40°C to 55°C) to a low temperature range (35°C to 40°C), the digestion temperature will decrease in stages, preventing excessive digestion gas generation. Degradation is prevented.

〔Effect of the invention〕

As explained above, the present invention controls the digestion temperature so that the amount of digestive gas generated is constant depending on the amount of organic matter input.
This has the effect of preventing energy loss and enabling planned energy-saving operation.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a wa diagram showing the relationship between the digestion temperature and the number of days of digestion, and Fig. 6 shows the relationship between the number of days of digestion and the amount of digestive gas generated per input organic matter. %
Fig. 4 is a block diagram showing another embodiment of the present invention;
FIG. 5 is a block diagram showing an example of a conventional temperature control device. In the figure, (1) is the digestion tank, (2) is the sludge supply pipe, and (3 is
) is the input sludge flow meter, (8) is the heating boiler, (9) is the fuel supply valve, α1 is the boiler temperature regulator, α is the digestion temperature regulator, (6) is the digestion temperature detector, and Q-bar. is the three-way switching valve, α◆ is the heat exchanger, QQ is the organic matter concentration measuring device for the input sludge, α force is the gas generation amount calculator for the input organic matter, θ barrel is the gas generation amount controller, (to) is the digestion gas flow rate The needle, α is the computing unit, (6) is the computing unit, 04 is the sludge concentration detector, and the same reference numerals in the figures indicate the same or equivalent parts. Agent: Patent Attorney Sanro Kimura Written Amendment to Hyakukari Proceedings (Spontaneous) 1982 97120 +” Commissioner of the Japan Patent Office 1, Indication of the case, Patent Application No. 1986-86090 2, Title of the invention Digestion tank temperature control device 3, Representative of the person making the amendment, Department 4, Agent 5, ←, “Detailed description of the invention” column of the specification subject to the amendment and drawing 6, Contents of the amendment ( 1) “Warming boiler” on page 2, line 17 of the specification is corrected to “separate boiler.” (2) [Fa inJ on page 7, line 4 of the specification is changed to [Fa
Correct with irJ. (3) Figure 5 of the drawings shall be amended as shown in the attached amended drawings. that's all

Claims (2)

[Claims] (1) Means for calculating the amount of digestive gas generated per organic matter fed into the digestion tank, means for determining the set value of the digestion temperature from the amount of generated digestive gas, and means for adjusting the digestion temperature so as to reach the set value of the digestion temperature. A digestion temperature control device for a digestion tank consisting of. (2) Claim 1, characterized in that the means for adjusting the digestion temperature adjusts the digestion temperature so that it changes stepwise within a predetermined upper and lower limit range and at a predetermined time. Temperature control device for the digester described.