EP-4741641-A1 - AMMONIA GASIFIER FOR A SELECTIVE CATALYTIC REDUCTION DEVICE, AND ASSOCIATED SYSTEMS AND METHODS

Abstract

Provided are embodiments for apparatuses, systems and methods for reducing emissions in an exhaust gas flow of an engine, the apparatus comprising: a reactor vessel positioned externally from the exhaust gas flow, the reactor vessel comprising an inlet and an outlet, the outlet in communication with the exhaust gas flow; an injector positioned within the reactor vessel, the injector receiving a reductant flow from the inlet of the reactor vessel and combining the reductant flow with a pressurized gas flow to generate a reductant spray; and an ammonia generation means within the reactor vessel, the ammonia generation means generating a gaseous reductant flow from the injected reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel.

Inventors

• STELZER, ROBERT M
• Puthuparampil, Jobin
• Pong, Henry Ho Yin
• Ostaltsov, Andrey

Assignees

• Safety Power Inc.

Dates

Publication Date

20260513

Application Date

20250502

Claims (16)

1. An apparatus for reducing emissions in an exhaust gas flow of an engine, the apparatus comprising: - a reactor vessel positioned externally from the exhaust gas flow, the reactor vessel comprising an inlet and an outlet, the outlet in communication with the exhaust gas flow; - an injector positioned within the reactor vessel, the injector receiving a reductant flow from the inlet of the reactor vessel and combining the reductant flow with a pressurized gas flow to generate a reductant spray; and - an ammonia generation means within the reactor vessel, the ammonia generation means generating a gaseous reductant flow from the injected reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel.
2. The apparatus of claim 1 wherein the ammonia generation means comprises at least one heating element positioned within the reactor vessel, the at least one heating element receiving the reductant spray to generate a gaseous reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel.
3. The apparatus of claim 1 wherein the ammonia generation means comprises a heated airflow stream received from a heater positioned externally from the reactor vessel, the heated airflow and the reductant spray combining within the reactor vessel to generate a gaseous reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel; and wherein the reactor vessel operates independently from the exhaust gas flow.
4. The apparatus of any one of claims 1 to 3, wherein the reductant comprises an aqueous urea solution.
5. The apparatus of any one of claims 1 to 4, wherein the gaseous reductant flow comprises ammonia.
6. The apparatus of any one of claims 1 to 5, wherein the one or more ammonia generation means comprise one or more high temperature heating elements configured to operate at a temperature above 500°C; and wherein an operating temperature of the one or more high temperature heating elements is independent of the temperature of the exhaust gas flow.
7. The apparatus of any one of claims 1 to 6 wherein the injector comprises a concentric tube, an outer layer of the concentric tube receiving the pressurized gas flow and an inner layer of the concentric tube receiving reductant flow.
8. A system for reducing emissions in an exhaust gas flow of an engine, the system comprising - an injector positioned within a reactor vessel, the reactor vessel positioned externally from the exhaust gas flow, the injector receiving a reductant flow from an inlet of the reactor vessel at a reductant flow rate and combining the reductant flow with a pressurized gas flow to generate a reductant spray; - an ammonia generation means within the reactor vessel, the ammonia generation means generating a gaseous reductant flow from the injected reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel; - a pre-treatment sensor in communication with the exhaust gas flow upstream of the reactor vessel outlet; and - a processor in communication with the pre-treatment sensor, the processor configured to: - receive an exhaust gas flow measurement from the pre-treatment sensor; - determine a revised reductant flow rate based on the exhaust gas flow measurement; - transmit a signal to the injector to adjust the reductant flow rate to the revised reductant flow rate.
9. The system of claim 8 wherein the ammonia generation means comprises at least one heating element positioned within the reactor vessel, the at least one heating element receiving the reductant spray to generate a gaseous reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via an outlet of the reactor vessel.
10. The system of claim 8 wherein the ammonia generation means comprises a heated airflow stream received from a heater positioned externally from the reactor vessel, the heated airflow and the reductant spray combining within the reactor vessel to generate a gaseous reductant flow, the gaseous reductant flow transmitted into the exhaust gas flow via the outlet of the reactor vessel; and wherein the reactor vessel operates independently from the exhaust gas flow.
11. The system of any one of claims 8 to 10, further comprising a reductant pump upstream of the injector, wherein the processor is configured to transmit a signal to the reductant pump to adjust the reductant flow rate.
12. The system of any one of claims 8 to 11, wherein the processor is configured to transmit a signal to the at least one heating element to control a temperature of the reactor vessel.
13. The system of any one of claims 8 to 12, further comprising a reductant valve upstream of the reactor vessel inlet, wherein the processor is configured to transmit a signal to the reductant valve to adjust the reductant flow rate to the injector.
14. The system of any one of claims 8 to 13, wherein the pre-treatment sensor is at least one selected from the group of: a NOx sensor, a temperature sensor, or an exhaust flow rate sensor.
15. The system of any one of claims 8 to 14, further comprising a post treatment sensor positioned in the exhaust gas flow downstream of the reactor vessel outlet, the post-treatment sensor transmitting a gaseous reductant measurement of the exhaust gas flow to the processor; and wherein the processor is configured to: determine the revised reductant flow rate based on the exhaust gas flow measurement and the gaseous concentration measurement.
16. The system of any one of claims 8 to 15, further comprising at least one heating element sensor, each of the at least one heating element sensor capturing a corresponding heating element temperature measurement; and wherein the processor is further configured to: - receive the at least one heating element temperature measurement; - determine a revised temperature set point for each of the at least one heating element based on the at least one heating element temperature measurement; and - transmit the revised temperature set point to the at least one heating element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority to US Provisional Application 63/716,837 filed Nov 6th 2024. FIELD The present invention relates generally to exhaust gas emission control for combustion devices such as boilers, generators and internal combustion engines. More specifically, the present embodiments are directed to an ammonia gasifier (and associated systems and methods) that efficiently reduce Nitrogen Oxides (NOx) emissions of the exhaust-gas flow associated with these combustion devices. BACKGROUND Exhaust gas emission control has become particularly important due to stringent regulatory emission limits on boilers, generators and reciprocating engines. A typical exhaust gas after-treatment system may comprise many different individual emission reduction functions in order to meet the regulatory emission standards. More specifically, the selective catalytic reduction (SCR) device is frequently used in the exhaust system of combustion devices to eliminate particles of nitrogen oxides (NOx) in the exhaust gas. The SCR device is normally located in the exhaust system downstream of the combustion that takes place in a boiler, generator or reciprocating engine. The SCR device contains a SCR catalyst to reduce NOx, particles in the exhaust gas as the SCR catalyst must be heated before it can be used to reduce NOx, particles. In other words, until the SCR catalyst reaches an activation temperature, which is the minimum temperature to which the SCR catalyst must be heated, the SCR catalyst does not provide NOx, emission reduction. Although the hot exhaust gas from the combustion in a boiler, generator or reciprocating engine heats up the SCR Catalyst, for certain applications the length of time required to heat up the SCR Catalyst using hot exhaust gas alone can be too long. SCR technology relies on a chemical reaction, which occurs between 260-540°C (500-1000F) to reduce NOx, particles in the exhaust gas. This commonly includes the use of gaseous ammonia provided by urea solution. Injecting gaseous ammonia is important because it is used as a reactant for reducing the NOx emissions at the SCR. Most emission regulations accept compliance at steady state, and in those cases, a potential 15-minute+ delay to achieve reductions is acceptable. However, certain air permits or other environmental controls may require a 1-hour average measurement or have other regulations that require a reduced delay. In these applications, the catalyst activation delay can result in non-compliance or extremely restrictive maintenance run times. Conventional solutions use the heat of the exhaust gas flow in order to vaporize urea that is sprayed into the gas flow from a nozzle. Restated, these conventional solutions do not generate gaseous ammonia independently of the exhaust gas flow. As noted above, it can take time for the exhaust gas flow and the SCR to achieve the necessary temperature for emissions reductions. The injection of urea into the exhaust gas flow before sufficient heating has occurred can cause pooling and liquid collection within the exhaust gas system, which can cause deposits to form as well as inadequate gaseous reductant generation because of these low temperatures. Due to the location of these conventional systems within the normal engine exhaust flow, they are not well accessible due to their location within the main exhaust system. Engines may have periodic testing to ensure they are available at short notice if needed. This periodic testing itself causes emissions, and can cause problematic elevated NOx emissions because engines in this situation will operate at low load (and the associated exhaust flow temperature will typically being below 250°C). Typically this would mean that the gaseous ammonia will not be formed from injected urea. There is therefore a need for improved emission control systems including an ammonia gasifier, and associated systems and methods for improving existing emission controls. SUMMARY Provided herein is an ammonia gasifier, and associated systems and methods. The present embodiments provide for gaseous ammonia generation even when the associated engine exhaust gas flow is below the normal operating temperature. This may allow for reduced NOx emissions across a wider range of engine operating conditions (especially at idle or low load). This may assist sites with many engines to have easier and better NOx emission control. In a first aspect, there is provided an apparatus for reducing emissions in an exhaust gas flow of an engine, the apparatus comprising: a reactor vessel positioned externally from the exhaust gas flow, the reactor vessel comprising an inlet and an outlet, the outlet in communication with the exhaust gas flow; an injector positioned within the reactor vessel, the injector receiving a reductant flow from the inlet of the reactor vessel and combining the reductant flow with a pressurized gas flow to generate a reductant spr