US-12617705-B2 - Applying chemical oxygen demand and heating value diagnostics to enhance performance of a SCWO process

Abstract

A system for on-line monitoring of a supercritical water oxidation (SCWO) process, the system including an SCWO reactor, a feedstock supply line which supplies a feedstock to the SCWO reactor, an oxidant supply line which supplies an oxidant to the SCWO reactor, at least one sensor which measures at least one parameter of the feedstock and the oxidant, and a controller which determines a Chemical Oxygen Demand (COD) and a Heating Value (HV) of the feedstock based on the at least one parameter, such that the controller adjusts the amount of the oxidant supplied to the SCWO reactor based upon the COD and the HV of the feedstock.

Inventors

• Yaacov Nagar
• David BALLENGHIEN
• Marc Deshusses

Assignees

• 374Water Inc.

Dates

Publication Date

20260505

Application Date

20221129

Claims (15)

1. 1 . A system for on-line monitoring of a supercritical water oxidation (SCWO) process, said system comprising: an SCWO reactor; a feedstock supply line which supplies a feedstock to said SCWO reactor; an oxidant supply line which supplies an oxidant to said SCWO reactor; at least one sensor which measures at least one parameter of said feedstock and said oxidant; a controller which determines a Chemical Oxygen Demand (COD) and a Heating Value (HV) of said feedstock based on said at least one parameter, such that said controller adjusts the amount of said oxidant supplied to said SCWO reactor based upon said COD and said HV of said feedstock; a co-fuel supply line which supplies a co-fuel to said SCWO reactor; and at least one co-fuel supply line sensor which measures at least one parameter of said co-fuel, wherein said controller adjusts the amount of said co-fuel based on said HV of said feedstock, wherein said controller determines said COD of said feedstock based on the following Equation 1 and said controller determines said HV of said feedstock based on the following Equation 2: the following equation 1 is: OMF ⁢ m . Ox ( t 0 ) - m ˙ F ⁢ D ( t 0 ) ⁢ COD F ⁢ D ( t 0 ) - m ˙ C ⁢ F ( t 0 ) ⁢ COD C ⁢ F ( t 0 ) = Q ˙ G ( t 0 + τ ) ⁢ 1 V M ( t 0 + τ ) ⁢ O 2 G ( t 0 + τ ) ⁢ M O 2 and, the following Equation 2 is: ( m ˙ o + m ˙ F ⁢ D ) ⁢ h ⁡ ( x i , T R , P ) = m ˙ o ⁢ h ⁡ ( x j , T o , P ) + m ˙ F ⁢ D ⁢ h ⁡ ( x k , T F ⁢ D , P ) + m ˙ F ⁢ D ⁢ H ⁢ V - Φ where, the indexes FD, CF, Ox and G stand respectively for said feedstock, said co-fuel, said oxidant, and a gas effluent stream of said SCWO reactor; OMF stands for the oxygen mass fraction in said oxidant; {dot over (m)} * stands for the mass flow rate of stream *; COD * stands for said COD of stream *; {dot over (Q)} G stands for the volumetric flow rate of said gas effluent stream; O 2 G stands for the oxygen volumetric concentration of said gas effluent stream; V M stands for the molar volume of said gas effluent stream; M O 2 stands for oxygen molar mass; τ stands for the system residence time; t 0 stands for the timestamp to which said COD values refer; h stands for the specific enthalpy function; x i stands for the mass fraction of compound i, where i varies over the list of all the compounds; T * stands for the temperature of stream *; P stands for pressure; and Φ stands for the heat losses within said SCWO system.
2. 2 . The system of claim 1 , wherein said COD is determined based on an oxygen mass balance calculation performed by said controller, and said controller uses said COD and said HV of said feedstock to determine a COD-HV relationship for said feedstock.
3. 3 . The system of claim 2 , wherein said controller uses said COD-HV relationship to generate a HV derived COD, wherein said HV derived COD is used by said controller to adjust the amount of said oxidant supplied to said SCWO reactor.
4. 4 . The system of claim 1 , further comprising: at least one heat exchanger which transfers heat from an effluent of said SCWO reactor to at least one of said oxidant and said feedstock.
5. 5 . The system of claim 1 , wherein said at least one sensor includes: a mass flow rate meter; a mass flowmeter; a temperature sensor; a pressure sensor; and an oxygen sensor, wherein said at least one sensor measures at least one parameter for at least one of: said feedstock; said oxidant; and an SCWO reactor effluent.
6. 6 . The system of claim 1 , wherein said controller calculates said COD and said HV of said feedstock periodically, said controller iteratively adjusting the supply of said oxidant.
7. 7 . The system of claim 1 , further comprising: a phase separator which separates an effluent of said SCWO reactor into a liquid effluent stream and said gas effluent stream, wherein said at least one sensor includes at least one of: a gas effluent stream flow rate meter; a gas effluent stream oxygen sensor; and a gas effluent stream temperature sensor.
8. 8 . The system of claim 1 , further comprising: a supply regulator for said oxidant, wherein said oxidant supply regulator is connected to said controller, and said controller adjusts the amount of said oxidant supplied to said SCWO reactor by sending a control signal to said oxidant supply regulator.
9. 9 . A method for an on-line monitoring of a supercritical water oxidation (SCWO) process, said method comprising: supplying a feedstock and an oxidant to an SCWO reactor; measuring at least one parameter of said feedstock and said oxidant with at least one sensor; determining, with a controller, a Chemical Oxygen Demand (COD) and a Heating Value (HV) of said feedstock based on said at least one parameter; adjusting the supply of said oxidant based on said COD and said HV of said feedstock; supplying a co-fuel to said SCWO reactor; and adjusting the supply of said co-fuel based on said HV of said feedstock, wherein said controller adjusts the amount of said co-fuel based on said HV of said feedstock, wherein said controller determines said COD of said feedstock based on the following Equation 1 and said controller determines said HV of said feedstock based on the following Equation 2: the following equation 1 is: OMF ⁢ m . Ox ( t 0 ) - m ˙ F ⁢ D ( t 0 ) ⁢ COD F ⁢ D ( t 0 ) - m ˙ C ⁢ F ( t 0 ) ⁢ COD C ⁢ F ( t 0 ) = Q ˙ G ( t 0 + τ ) ⁢ 1 V M ( t 0 + τ ) ⁢ O 2 G ( t 0 + τ ) ⁢ M O 2 and, the following Equation 2 is: ( {dot over (m)} O +{dot over (m)} FD ) h ( x i ,T R ,P )= {dot over (m)} O h ( x j ,T O ,P )+ {dot over (m)} FD h ( x k ,T FD ,P )+ {dot over (m)} FD HV−Φ where, the indexes FD, CF, Ox and G stand respectively for said feedstock, said co-fuel, said oxidant, and a gas effluent stream of said SCWO reactor; OMF stands for the oxygen mass fraction in said oxidant; {dot over (m)} * stands for the mass flow rate of stream *; COD * stands for said COD of stream *; {dot over (Q)} G stands for the volumetric flow rate of said gas effluent stream; O 2 G stands for the oxygen volumetric concentration of said gas effluent stream; V M stands for the molar volume of said gas effluent stream; M O 2 stands for oxygen molar mass; τ stands for the system residence time; t 0 stands for the timestamp to which said COD values refer; h stands for the specific enthalpy function; x i stands for the mass fraction of compound i, where i varies over the list of all the compounds; T * stands for the temperature of stream *; P stands for pressure; and Φ stands for the heat losses within said SCWO system.
10. 10 . The method of claim 9 , wherein said COD is determined based on an oxygen mass balance calculation performed by said controller, and said controller uses said COD and said HV of said feedstock to determine a COD-HV relationship for said feedstock.
11. 11 . The method of claim 10 , wherein said controller uses said COD-HV relationship to generate a HV derived COD, wherein said HV derived COD is used by said controller to adjust the amount of said oxidant supplied to said SCWO reactor.
12. 12 . The method of claim 9 , further comprising: preheating at least one of said oxidant and said feedstock using a heat exchanger, wherein said heat exchanger transfers heat from an effluent of said SCWO reactor to at least one of said oxidant and said feedstock.
13. 13 . The method of claim 9 , wherein said at least one sensor includes: a mass flow rate meter; a mass flowmeter; a temperature sensor; a pressure sensor; and an oxygen sensor, wherein said at least one sensor measures at least one parameter for at least one of: said feedstock; said oxidant; and an SCWO reactor effluent.
14. 14 . The method of claim 9 , wherein said controller calculates said COD and said HV of said feedstock periodically, said controller iteratively adjusting the supply of said oxidant.
15. 15 . The method of claim 9 , further comprising: separating, with a phase separator, an effluent of said SCWO reactor into a liquid effluent stream and said gas effluent stream, wherein said at least one sensor includes at least one of: a gas effluent stream flow rate meter; a gas effluent stream oxygen sensor; and a gas effluent stream temperature sensor.

Description

RELATED APPLICATION The present application is a Non-Provisional of, and claims 35 U.S.C. 119 priority from, U.S. Patent Application Ser. No. 63/284,469 filed Nov. 30, 2021, the entire contents of which are incorporated by reference herein. BACKGROUND Waste processing remains an important priority in today's society, and especially as it relates to waste which includes organic material. This waste includes sludge, which is a slurry, liquid waste, and waste with a large organic material component. One way of dealing with this waste is through treatment utilizing supercritical water oxidation (SCWO) technology. A reaction utilizing SCWO technology involves reacting the waste with air at temperatures and pressures above the critical point of water (374° C., 221 Bar) to convert all of the organic matter of the waste into clean water and carbon dioxide (CO2) in a short period of time. Under these conditions, organic matter is typically oxidized at high reaction rates, resulting in complete conversion of the organic matter to CO2, and usable water at reaction times as short as a few seconds. The resulting water is divided into two streams, one mineral and one distilled water. The mineral stream contains suspended and dissolved inorganic minerals, and can optionally be utilized as fertilizer, following further processing. One beneficial feature of using SCWO technology is that the continuous process utilizes the energy embedded in the waste. When the energy balance is positive, this feature allows the units to operate off-the-grid while increasing the system's resiliency. Another benefit is that SCWO systems are more compact compared to other organic waste processing technologies. Further, it is possible to provide a system that normally does not require any reagents or consumables to operate, and that requires no additional external energy other than the initial energy embedded in the waste undergoing treatment and the initial heat provided to the system. SCWO has been successfully applied to the destruction of problematic contaminants such as chemical weapons, PCBs, chlorinated solvents, coking wastewater, landfill leachate, oily wastes, PFAS, and dye-house wastewater. Unlike other hydrothermal treatment which generally produces an effluent liquid requiring additional processing prior to disposal, SCWO treatment yields relatively clean water. Moreover, formation of NOx, SOx, and other usual by-products of combustion is significantly reduced because of the relatively low process temperatures and water medium of the reaction the unique properties of the medium in which the reaction takes place. One drawback of SCWO processes is that a significant amount of power is consumed by the air compressor to compress air from ambient pressure to above 3200 psi. This compressed air is the source of oxygen in the process, which needs to be provided in sufficient quantities to attain proper treatment of the waste. Additionally, maintaining an adequate air to feedstock ratio is important to achieving proper performance and improved operation of the SCWO process. Further, co-fuel, which is added on demand to the feedstock streams to control the reactor temperature, also contains oxygen demand which must be taken into account when determining the air to feedstock ratio. While maintaining an adequate air to feedstock ratio is important, just as important is the speed with which the system can react to achieve the needed air to feedstock ratio. In particular, delay between the reaction and the analysis of the corresponding vent-gas results in process control challenges which may cause suboptimal performance of the system. Using a traditional feedback control loop of the vent stream in an industrial scaled system might introduce a 5-10 minute lag and any sudden change in feedstock Chemical Oxygen Demand (COD) would remain unnoticed for that same amount of time, thereby delaying corrective action. Accordingly, the lag in adjusting the air to feedstock ratio presents the risk that the system will have insufficient oxygen, causing incomplete oxidation and generation of unwanted by-products such as carbon monoxide, methane, etc. Also, excess oxygen often results in excessive power consumption. Therefore, there is a need for an alternative, feedforward and rapid method for COD estimation in a SCWO process, especially a method that enables fast corrective actions. SUMMARY The above-listed need is met or exceeded by the present method which uses a SCWO process for monitoring Chemical Oxygen Demand (COD) and Heating Value (HV) of feedstock. Moreover, the particular HV, whether it is a Lower Heating Value (LHV) or a Higher Heating Value (HHV) is not important, as long as the same HV is consistently used by the method. In particular, the present system provides a SCWO process which incorporates a feedstock COD monitor and an HV monitor, both of which operate in real-time. These monitors generate estimated values which are used for improved pr